Search

Besides waste gas and liquid, high-temperature particles are important media of waste heat and their temperature exceeds 1000°C on many occasions. The cross-flow heat transfer is important in this waste heat recovering process, but there are few references reported about the theoretical modeling. Therefore, a theoretical model was developed for the cooling process in a horizontal moving bed of high-temperature particles. The purpose of the study is to estimate the influence of temperature field and flow field on heat transfer and bed resistance in the cross-flow cooling process. Three modes such as conduction, convection and radiation are considered in the model. This model was used to analyze heat transfer in a horizontal moving bed of cement clinker and was verified by comparing some simulative results with the tested and collected data from an actual cement clinker plant in China. The simulative temperature of cement clinker was 200°C as same as that collected in the actual cement clinker plant. In the moving bed, the highest pressure drop occurs at the front top and the strongest heat transfer occurs at the front bottom. In the considered conditions with even distribution of cooling air, the highest pressure drop is 3205.9 Pa/m, the biggest specific heat transfer rate of 1683.1 kW/m³. Thermal radiation plays a minor role in this cooling process with the biggest radiation proportion is only 0.149 at the front top. This mode plays a minor role in this cooling process of the cement clinker, comparing with the thermal convection. With constant flow rate of cooling air, the distribution can regulate the local cooling rate rather than the final temperature of the cement clinker. [ABSTRACT FROM AUTHOR]

China has ranked first worldwide in graphite imports in recent years, facing a graphite supply risk. Coal-hosted graphite is the focus of future graphite deposit exploration. The current research on the enrichment and mineralization mechanism of coal-hosted graphite is superficial, and the identification standard of coal-hosted graphite is incomprehensive, restricting the exploration of coal-hosted graphite mineral resources and the development of coal metamorphic evolution theory. In this study, the Caotangou–Meigoucoal-hosted graphite deposit in western Qinling Mountain was taken as a case study for dissection. Based on the data from 1/50,000 and 1/200,000 regional geological mapping and the data of graphite mines in the study area, the samples were systematically collected and analyzed to explore the mechanism of coal graphitization through a 1:5000 geological profile survey, 1/10,000 geological mapping in key areas, and the investigation and cataloguing of abandoned coal-hosted graphite adit. The result was that there were two main coal-hosted graphite ore bodies, striking from nearly east to west. The Rmax values of the samples were 7.23–8.15%, the average values of Vdaf were around 5.0%, the d002 value of the II ore body was 0.3433–0.3389 nm, the d002 value of the I ore body was mainly 0.3418–0.3429 nm, the graphitization degree G value of the II ore body was 8.14–59.30%, the graphitization degree G value of the II ore body was 12.79–25.58%. The II ore body was coal-hosted graphite, while some samples of the I ore body were coal-hosted graphite, and some samples were coal. The magmatic heat controls the thermal metamorphism of coal seams to form graphite. The closer the distance to the magma body, the larger the crystals, and the higher the euhedral degree, indicating the higher degree of coal seam metamorphism. The nearly north–south compressive structures mainly provided effective tectonic stress for the evolution of coal graphitization during the Yanshan period; the basic structural units (BSUs) rotated and rearranged, eventually forming a straight graphite structure, and tectonic stress catalyzed the graphitization process. The coal-hosted graphite deposits formed under the dual effects of magmatic heat transfer and tectonic stress. [ABSTRACT FROM AUTHOR]

A superconducting magnet system is developed for the application of high-frequency gyrotrons at Wuhan National High Magnetic Field Center, China. The operating cost for the magnet is dominated by refrigeration power. To reduce the heat load for cryogenic systems, a pair of YBCO binary current leads is designed by consideration of the industrial concentration of type II high-temperature superconducting YBCO material. In this paper, a simulation model is proposed to perform the electromagnetic-thermal coupling analysis of these YBCO binary leads under different operating conditions by combining a partial element equivalent circuit method and finite volume method. The simulation code can improve computational efficiency and enable high-accuracy coupling between the electromagnetic field and heat transfer process. In the steady state, the heat leakage at the 4.2 K cold end of the YBCO binary leads depends mainly on the geometric parameters of the YBCO tape, especially the cross-sectional area of the copper layer in the YBCO tape. The cooling mode and liquid helium level also have a significant impact on the heat leakage level. The optimal outer diameter of the normal copper section is identified, and the optimum value is largely influenced by the effective cooling power imposed on the cold end of the normal copper section. In the transient state, simulations for the charging process and the loss of cooling accident are performed, along with a detailed analysis of the electromagnetic-thermal response features of the leads under these conditions. The results indicate that the YBCO binary current leads possess high thermal stability and an ample time margin for the magnet system to be demagnetized. [ABSTRACT FROM AUTHOR]

The response potential of demand-side resources is becoming increasingly significant in integrated energy system (IES) operations. In addition, to ensure the effective participation of system devices, their actual responsiveness at different timescales should be considered. Based on these considerations, this paper proposes an IES multi-timescale operation optimization strategy that incorporates multiple forms of integrated demand response (IDR) and considers the response characteristics of the equipment. First, the multi-timescale characteristics of IDR are analyzed. Moreover, a multi-timescale operation model of IES that comprises day-ahead, intraday, and real-time stages is further established. In the day-ahead dispatch, a low-carbon economic scheduling model is developed by considering the shifting demand response (DR) and the cost of carbon emissions. In the intraday scheduling, noting that cooling and heat energy transmission possess slow dynamic characteristics, a rolling optimization model for cooling/heating coupled equipment considering load shedding and substituting DR is established. In real-time scheduling, the output of electric/gas coupled equipment is adjusted. Finally, an industrial park-type IES in northern China was selected as an example for a case study. The results show that (1) the IDR multi-timescale response strategy can exploit different types of demand-side flexibility resources. After implementing the shifting DR, the peak-to-valley difference of the electric load curve was reduced by 20%, and the total system cost was reduced by 2.3%. After implementing load shedding, the maximum load differences per unit period of the electric, heat, and cooling load curves decreased by 18.7%, 40.0%, and 68.9%, respectively. (2) By refining the timescale of IES optimization, the proposed model can effectively ensure the energy supply and demand balance of the system under different load scenarios and reduce the system operation cost. After applying the model to simulation in three typical days (transition season, summer, and winter), the penalty costs of lost loads reduce by ¥3650, ¥3807, and ¥3599, respectively, and the total system costs decrease by 17.4%, 16.1%, and 16.2%, respectively. [ABSTRACT FROM AUTHOR]

The Eastern Helan Mountain can be the largest concentrated and contiguous producing areas for the wine grape in China. Specifically, the wine grape planting area reached 388.7 square kilometers in Ningxia by the end of 2022, accounting for nearly 1/3 of the nation, and the comprehensive output value exceeded 30 billion Yuan. However, the extremely low temperatures (down to -30.0℃) in winter in the eastern part of the Helan Mountains can lead to the occurrence of overwintering frost damage, which greatly limits the sustainable development of Ningxia's grape industry. In this study, a gravity heat pipe system was designed using shallow groundwater geothermal energy for the soil warming in the root zone of grapes. Numerical simulation was also carried out to analyze the influence range and distribution of the gravity heat pipe temperature field under different spacing. A series of field experiments were used to verify the working performance of the gravity heat pipe and the warming characteristics of the soil. The results show that the soil temperature field was evenly spread around the gravity heat pipe. The temperature field around the heat pipe was divided into four regions, according to the temperature level: the temperature range was 5.0-8.50℃ high-temperature affected region â… , the temperature range was 0-5.0℃ medium-temperature affected region â…¡, the temperature range was -2.57-0 ℃ low-temperature affected region â…¢, and the temperature field was not affected region â…£. The highest temperature (8.50 ℃) appeared in the temperature field area â…  condensation section pipe wall, whereas, the lowest temperature (-2.57 ℃) was in the temperature field unaffected area â…£. In addition, the diameter of the medium temperature affected area of the heat pipe in the soil was 30.8 cm horizontally and 32.8 cm vertically, where the grape roots were not affected by frost. There were evenly distributed temperature fields around the heat pipes partially overlapped and the temperature fields under the conditions of 10 cm burial depth and 15 cm spacing between adjacent heat pipes. The soil temperature increased by 7.0 ℃ on average in the experimental group during the test period, compared with the control group, indicating the outstanding increase in temperature. The maximum temperature difference was 3.5 ℃ between the evaporation and condensation sections during the normal operation of the gravity heat pipe. The maximum temperature differences were 1.0 and 0.2 ℃ within the evaporation section, and within the adiabatic section, respectively, indicating the excellent isothermal distribution. The average start-up and operating temperature difference of the heat pipe were 5.4 and 2.9 ℃, respectively. The clean and renewable shallow geothermal energy was taken as a source of heating energy in the root zone of grapes, which was in line with the current green development concept. The finding can provide the theoretical basis and technical support to treat the frost damage in the root zone of grapes. In addition, a way was proposed to realize the development and utilization of shallow geothermal energy using gravity heat pipes. The Eastern Helan Mountain can be the largest concentrated and contiguous producing areas for the wine grape in China. Specifically, the wine grape planting area reached 388.7 square kilometers in Ningxia by the end of 2022, accounting for nearly 1/3 of the nation, and the comprehensive output value exceeded 30 billion Yuan. However, the extremely low temperatures (down to -30.0℃) in winter in the eastern part of the Helan Mountains can lead to the occurrence of overwintering frost damage, which greatly limits the sustainable development of Ningxia's grape industry. In this study, a gravity heat pipe system was designed using shallow groundwater geothermal energy for the soil warming in the root zone of grapes. Numerical simulation was also carried out to analyze the influence range and distribution of the gravity heat pipe temperature field under different spacing. A series of field experiments were used to verify the working performance of the gravity heat pipe and the warming characteristics of the soil. The results show that the soil temperature field was evenly spread around the gravity heat pipe. The temperature field around the heat pipe was divided into four regions, according to the temperature level: the temperature range was 5.0-8.50℃ high-temperature affected region Ⅰ, the temperature range was 0-5.0℃ medium-temperature affected region Ⅱ, the temperature range was -2.57-0 ℃ low-temperature affected region Ⅲ, and the temperature field was not affected region Ⅳ. The highest temperature (8.50 ℃) appeared in the temperature field area Ⅰ condensation section pipe wall, whereas, the lowest temperature (-2.57 ℃) was in the temperature field unaffected area Ⅳ. In addition, the diameter of the medium temperature affected area of the heat pipe in the soil was 30.8 cm horizontally and 32.8 cm vertically, where the grape roots were not affected by frost. There were evenly distributed temperature fields around the heat pipes partially overlapped and the temperature fields under the conditions of 10 cm burial depth and 15 cm spacing between adjacent heat pipes. The soil temperature increased by 7.0 ℃ on average in the experimental group during the test period, compared with the control group, indicating the outstanding increase in temperature. The maximum temperature difference was 3.5 ℃ between the evaporation and condensation sections during the normal operation of the gravity heat pipe. The maximum temperature differences were 1.0 and 0.2 ℃ within the evaporation section, and within the adiabatic section, respectively, indicating the excellent isothermal distribution. The average start-up and operating temperature difference of the heat pipe were 5.4 and 2.9 ℃, respectively. The clean and renewable shallow geothermal energy was taken as a source of heating energy in the root zone of grapes, which was in line with the current green development concept. The finding can provide the theoretical basis and technical support to treat the frost damage in the root zone of grapes. In addition, a way was proposed to realize the development and utilization of shallow geothermal energy using gravity heat pipes. [ABSTRACT FROM AUTHOR]

Lycium barbarum is one of the most popular herbs in China. The high medicinal value can serve as a functional food rich in nutrients (such as polysaccharides, plant flavonoids, and carotenoids), further promoting glucose and lipid metabolism for better immune system, and mental efficiency, and even preventing neurodegeneration. The berry fruits with high water content can be dried to improve their shelf life using vacuum freeze drying. In this study, a numerical simulation was carried out to explore the heat and mass transfer, stress, and strain of Lycium barbarum during freeze-vacuum drying. Among them, the heat and mass transfer was a benefit to exploring the drying mechanism of Lycium barbarum freeze during vacuum drying. The stress and strain was to explore the cellular changes of Lycium barbarum freeze-vacuum during drying. The temperature experiment was carried out by vacuum freeze dryer. The pre-freezing stage was set at -40 for about 4 hours,°C then the vacuum was drawn at two heating rates (5, and 10 /h). The constant temperature was maintained when the heating°C plate temperature reached 40 . The cell change experiment was carried out by FDCS196 hot and cold table. The whole°C process was combined with the microscope and CCD camera, in order to obtain the real-time image of berry cells. The heat-mass-stress coupling of the drying was dominated by the high quality of the products. The heat-mass-structure coupling model during vacuum freeze drying was established to use binarization processing using the experimental image of fresh berry slices. The temperature, moisture, as well as internal stress, and strain of the fresh berry sample, were analyzed and then verified by experiments during vacuum freeze drying. The results showed that the length shrinkage (Sl) and equivalent diameter contraction (Sd) of berry tissue cells were always negative during the pre-freezing process, indicating the ever-expanding cells. By contrast, the cell shape coefficient (Sf) was increasing all the time. At the same time, the maximum stress was found on the cells, when the cells were completely frozen. The moisture of the sample during the simulation was fitted better with the WangandSingh and HendersonandPabis models, indicating the more suitable WangandSingh model(R² = 0.983). The experimental results show that the temperature of samples during the simulation was highly consistent with the experiment, indicating the better performance of the model. In addition, the cell shape was gradually altered around in the varying position with the decrease of sample temperature in the process of the pre-freezing experiment(R² = 0.857). A better consistency was found with the analysis data of stress and strain of sample cells during simulation.The research results can provide reference for the optimization of vacuum freeze drying system and the scientific formulation of process parameters. [ABSTRACT FROM AUTHOR]

• SACOP of the LDHC-SAHP is about 0.73 smaller than that of the LDHC-HAHP. • Energy transfer process of LDHC-HAHP is more advanced than that of LDHC-SAHP. • Centralized and distributed thermal storages can solve solar energy time-discrepancy. • Half-effect absorption heat pump is more suitable for the new proposed scheme. • SACOP and economic heat transmission distance of LDHC-HAHP are about 11.6 and 18 km. Developing solar energy source for space heating and cooling contributes to achieving the target of China's carbon emission peak by 2030. However, the conventional solar-driven heating systems integrated with heat pump or natural gas boiler are featured by short economic heat transmission distance and small solar fraction, and can't cover the demand of the large-scale solar-driven district heating and cooling systems. To solve the problem, two configurations of solar-driven low temperature district heating and cooling system are proposed. One is integrated with distributed single-effect water-lithium bromide absorption heat pumps, and the other is integrated with distributed half-effect water-lithium bromide absorption heat pumps. The distributed absorption heat pumps are located in the energy stations for reducing return temperature of the primary network, which helps to enlarge temperature difference between supply and return and improve solar collector performance. The analyzed results indicate that, in the energy station, replacing single-effect water-lithium bromide absorption heat pump by half-effect one can improve system annual coefficient of performance by about 0.73, reduce cooling cost by about 6.04 ¥/GJ, and increase economic heat transmission distance by about 2.6 km. Thus, the proposed solar-driven low temperature district heating and cooling system integrated with distributed half-effect water-lithium bromide absorption heat pumps has an advanced energy conversion and transfer process, and its economic heat transmission distance is about 18.3 km. Thus, application of the proposed solar-driven low temperature district heating and cooling system integrated with distributed half-effect water-lithium bromide absorption heat pumps would be promising in Northern China. [ABSTRACT FROM AUTHOR]

At present, China's high-speed rail is in a period of rapid development. Most of the refrigerants used in Chinese motor train units at this stage are still R134a and R407c, which have an impact on the environment. In response to the environmental protection concept of green travel, it is of great significance to study the air conditioning system of motor train units using CO2 refrigerant. Using CFD simulation analysis technology, the heat transfer performance of the air side of the CO2 finned tube evaporator used in the air conditioning system of the motor train unit is studied. We select the air outlet temperature, pressure drop, heat transfer factor, and resistance factor as the objective function, in addition, monitoring points are set up in the air flow channel to monitor the turbulent flow field and pipe wall pressure. Our research shows that the cooling capacity of the CO2 evaporator can reach up to 29.76 kW, which can meet the heat exchange required in the air conditioning system of the motor train unit. In order to obtain a better structure and the conditions of the heat transfer effect, structural optimization was conducted. The simulation results demonstrate several trends: (i) With the augment of the air inlet velocity, the cooling capacity of the evaporator increases and the heat exchange effect improves; when the air inlet ve > 2.2 m/s, the effect of continuing to augment ve on heat exchange is weak. (ii) Following appropriate reduction of the diameter of the heat exchange tube, the wind resistance is reduced and the cooling capacity of the evaporator is improved. (iii) With the enlargement of the fin spacing, the turbulent motion in the flow channel can be fully developed, there is a peak in the change in the heat exchange tube area optimization factor, and the optimal fin spacing is between 1.6 mm and 1.7 mm; at this time, the average turbulent kinetic energy of the air side is larger and the turbulent dissipation rate is smaller. These results provide a reference for the practical application of CO2 refrigerant in the motor train unit. [ABSTRACT FROM AUTHOR]

This paper introduces the application background of plate-fin heat exchanger and summarizes the research process of plate-fin heat exchanger at domestic and abroad. Furthermore, this paper summarizes the main research direction and existing problems in plate-fin heat exchanger in FLNG. The analysis results show that plate-fin heat exchanger is the main heat exchangers during the natural gas liquefaction process in FLNG, which has a broad application prospect with the extraction of the offshore natural gas in China. [ABSTRACT FROM AUTHOR]

China is a large agricultural country that is leading worldwide in the annual number of agricultural products and exports. However, the growth and harvest of fruits and vegetables are greatly affected by geographical conditions, climate and other factors, which will lead to their rotting in peak season and shortages in the off-season. Therefore, it is necessary to vigorously promote the development of drying technology. The explosion puffing technology at low temperature and high pressure is a kind of compound drying technology which can enable the puffed product to obtain the advantages of honeycomb, good rehydration, a short running time, etc. With the guidance of the theory of heat and mass transfer and relevant thermodynamics laws, this study has established high-pressure extruding technology in low-temperature heating; expanded the two-phase theoretical model, using mass conservation and the law of the conservation of energy to analyze the coupled heat and mass transfer process and influencing factors; and researched the influence of the operation temperature, pressure and time on the properties of dried fruit. [ABSTRACT FROM AUTHOR]

As an alternative energy for fossil fuels, geothermal reserve is abundant. In recent years, scholars have investigated geothermal wells through numerical simulations. To the best of our knowledge, many studies have explored the influence factors of thermal power over time, and few studies have investigated the heat transfer mechanism between wellbore and formation in different circumstances. This paper aims to established a transient numerical heat transfer model of U-shaped closed-loop geothermal system with long horizontal section, which can simulate the temperature distribution and heat transfer mechanism during the whole wellbore formation. In the model, the convection term is discretized by using the second-order upwind scheme, and the finite volume method is used to solve it. The numerical results are proven to be correct by comparing with the field data of a well in China. Subsequently, the influence mechanism of fluid type, insulation casing length, fluid injection temperature, flow rate, and horizontal section length on thermal power is explored. The optimal depth of insulation casing under different injection temperatures, flow rates, and horizontal section lengths is suggested so as to provide crucial guidance for engineering practice. [ABSTRACT FROM AUTHOR]

To address the problems of low power generation efficiency and low security of solar photovoltaic cells, a novel and versatile PV panel cooling strategy was proposed; which employed an absorbent hydrogel evaporative (AHE) cooling with 3D porous copper foam (CF) composite structure as an effective cooling component. By comparing natural cooling, comprehensive indoor simulated and outdoor experimental studies were conducted to explore the feasibility of enhancing the electrical output performance of PV cells. The effects of solar irradiation, environment humidity, ambient temperature and wind speed on heat transfer performance and the generated electricity power efficiency of PV with CF-AHE cooling panel were comprehensively analyzed and discussed. Present research demonstrated that the CF-AHE cooling layer of three solar irradiations (0.8, 1.0 and 1.2 sun conditions) could remove 449∼713W/m2 of heat from a photovoltaic cell, which significantly out-performed that of general cooling methodology depending on wind or buoyancy driven ventilation. The results further indicated that CF-AHE significantly reduces the cell temperature, enhancing the temperature uniformity of PV cell modules, i.e., the PV cell temperature ranges from 43–46 °C, markedly lower than the 53–66 °C observed with natural cooling. Additionally, average electrical efficiencies were enhanced by 4.69 %, 8.53 % and 12.84 % compared with that of natural cooling method, respectively. Subsequently, in the field test conducted in Wuhan city of China , current results further showed that our proposed cooling unit has boosted the power generation of PV panels by 14.01 % and reduced PV surface temperature by no less than 10 °C, simultaneously. Therefore, CF-AHE cooling structure can furnish excellent heat transfer characteristics and efficient electrical generation performance of PV panel. This research will provide valuable guidance for design of photovoltaic-AHE cooling systems and verifies the feasibility of such systems. [Display omitted] • Nano structures of porous copper foam and absorbent hydrogel were firstly designed. • An absorbent hydrogel evaporative (AHE) cooling with 3D porous copper foam (CF) was proposed. • Power generation and thermal management of PVs could be simultaneously enhanced by CF-AHE. • Potentials on commercial PVs have been demonstrated both by on-site and lab experiments. • AHE-CF could be especially advantageous in the regions of high temperature and humidity. [ABSTRACT FROM AUTHOR]

Fine flow and heat transfer characteristics are critical to nuclear reactor safety. However, a comprehensive CFD calculation of the entire reactor core requires substantial computing resources, restricting the research domain's scope. To address this issue, we propose a Distributed Parallel (DP) computing scheme, tailored specifically for reactor cores using plate-type fuel assemblies. This study focuses on the thermal-hydraulic calculation of the large domain of a reactor core utilizing plate-type fuel assembly, based on the Computational Fluid Dynamics (CFD) method. This innovative solution enables the completion of extensive domain CFD calculations using modestly equipped personal workstations (8 cores, 128G RAM), which traditionally would require supercomputing platforms. To verify the distributed-parallel computing technique, it is successfully applied to all standard, full-length fuel assemblies in the China Advanced Research Reactor (CARR). In the result analysis, it was observed that detailed results could be obtained with reduced computational resources, demonstrating a significant breakthrough for CFD engineering analysis. [ABSTRACT FROM AUTHOR]

Chinese solar greenhouses (CSGs) are characterized by unique walls to reduce the transmission of heat and promote the energy conservation in winter production, which promotes cultivation in the northeast region of China in winter. Effective selection of insulation material is important for the CSG based on the energy consumption and economic analysis. However, choosing the thickness of the insulation material in walls often discussed with the structure of CSG. There is a lack of research combing the optimal insulation thickness for improving the energy conservation. The aim of this study was to find the optimum insulation thickness during the energy conservation based on the structure of walls, the energy consumption in local climatic conditions, the cost of insulation material, and economic payback period over a lifetime. By the economic analysis of insulation thickness, thermal resistance, lifetime energy saving, and payback period, three kinds of typical walls (clay brick (CB), hollow concrete block (HCB) and fly ash block (FAB)) combed with four insulation materials including the expanded polystyrene, the foamed PVC, the perlite, and the rock wool were calculated. The optimum insulation thickness can be found when energy savings reached the maximum. In the northeast region, the association of FAB with rock wool as the insulation layer was the most economic composite wall structure. The optimum insulation thickness was 0.05 m, with the cost only 5 USD/m2. The thermal resistance of composite wall had a significant effect on the payback period. When thermal resistance increased from 0.2 to 1.2 m2K/W, the payback period varied from 0.4 to 4.3 years. What is more, the energy consumption in local climatic conditions had a more significant effect on payback period. It can be assumed that insulation materials are more favored in cold climatic regions where heating degree-days over 1600 °C days for payback periods is less than 2 years. These results have strong practical and economical significance in saving energy and improving the environment of CSG. [ABSTRACT FROM AUTHOR]

Spectral selective absorption film (SSAF), a solar control film, has a special energy-saving mechanism. In the previous studies of SSAF coated glazing systems, thermal parameters (global thermal transmittance (U) and solar heat gain coefficient (SHGC)) calculated by traditional algorithms were not verified. In order to evaluate the energy-saving effect of SSAF coated glazing systems accurately, U and the SHGC were calibrated and then used for energy consumption simulation. Firstly, the simulation models of the heat transfer process of SSAF coated glazing systems were established by COMSOL Multiphysics, considering simplified linear attenuation of radiative transfer. After being validated, the simulation models were used for the calibration of U and SHGC by the Multiple Linear Regression (MLR) model. As a result, the calibration coefficients of U and SHGC are 1.126 and 1.689, respectively. Secondly, the thermal parameters of SSAF coated glazing systems calibrated by the calibration coefficients were used for a building energy consumption simulation case. The result showed that the inner surface is the best coating position for single glazing systems (SG), while the outer surface is the best coating position for double glazing systems (DG) in hot summer and cold winter zone, hot summer and warm winter zone and the moderate zone of China. [ABSTRACT FROM AUTHOR]

The thermal and optical performance in coating material of exterior walls affected the thermal action from the outdoor thermal environment indirectly, but there was the contrary thermal requirement in winter and summer, which could not be met by the constant-reflectivity coating. To overcome this drawback, the variable-reflectivity coating was analyzed and evaluated by taking three constant-reflectivity coatings as the references. The thermal transfer model with dynamic radiation reflectivity was built to simulate the thermal process of exterior walls in the whole year. Numerical results showed that the constant-reflectivity coating had poor seasonal adaptability with the best performance in some certain months and the poorest behavior in other months, while the variable-reflectivity coating had the better seasonal adaptability to dampen the heat gain in summer and promote the heat gain in winter. Although the variable-reflectivity coating could not show the optimal in all months, its overall performance played the best in the whole year. And compared with constant-reflectivity coating with radiation reflectivity of 90%, 50% and 10%, the variable-reflectivity coating could reduce the annual heating and cooling loads by 2.45%, 16.67% and 46.46%, respectively, in the studied Nanjing City of China. [ABSTRACT FROM AUTHOR]

With the increase of residents' requirements for the living environment, the current indoor thermal environment cannot meet the needs of modern rural residents who live in the northeast of Sichuan, China. Passive energy-saving strategies can not only improve the thermal performance of envelopes but also create high economic benefits. Evaluating the application effect of passive energy-saving strategies for traditional dwellings can provide a guide for local residents and policy makers to select rational passive strategies. Seven energy-saving strategies are proposed based on the current local building construction and heat transfer model, and then their energy-saving potential is evaluated by using EnergyPlus and the dynamic investment payback period method. Results show that adding exterior envelope insulation and setting on-top sunspaces on the roof simultaneously can save 83.9% of building energy consumption. However, the most economic energy-saving strategy is only employing exterior envelope insulation for local traditional dwellings when considering the economy. It can save 842 CNY/m2 during 100 years and its dynamic investment payback period is 14.1 years. In addition, building orientation also affects the energy-saving effects and the energy-saving rate can be increased by 8.4% under the optimal orientation (facing south) compared with the worst orientation (facing west). [ABSTRACT FROM AUTHOR]

• A three-dimensional unsteady state mathematical model of the multi-field coupling of backfill body, tube and fracture was established. • A test bench was designed and built to verify the three-dimensional coupling model. • The effects of a single fracture position, aperture and fractured depth on the heat extraction performance of a full-size BFHEs unit in the fully dry or fully saturated conditions were investigated. • The combined effects of multiple fractures on the performance of a BFHES unit were discussed. Thermal hazards in deep mines can be mined synergistically with the deposit as associated geothermal energy resources. Backfill heat exchangers (BFHEs) as a combination of mine backfilling and ground heat exchanger technology are one of the effective methods to realize ore deposit-geothermal energy synergy mining. However, in the complex environment of deep mines, BFHEs will inevitably suffer from fracture damage during long-term heat storage/release cycle operation, which will affect their working performance. To address this problem, this paper established a scaled-down experimental setup for fractured BFHEs units, and used the experimental data to verify the accuracy of the established three-dimensional transient heat transfer mathematical model of the BFHEs unit. Numerical simulation methods were used to investigate the effects of the position, aperture and fractured depth of a single fracture on the heat extraction performance of the BFHEs unit under fully dry or fully saturated working conditions. Significant differences were found in the effect of different fracture positions on the heat extraction capacity of the BFHEs unit. The extraction of geothermal heat by the BFHEs unit was favored when it was in the middle of two tubes, while the opposite was true for other positions. The effect of fracture on the heat extraction capacity of the BFHEs unit increased linearly with fracture aperture. The effect of the fractured depth was relatively greater in the 1/2–3/4 H b range. The presence of groundwater significantly reduced the effect of the fracture. The effect of the fracture on the heat extraction capacity of the BFHEs unit was reduced by more than 80 % by changing the operating conditions from fully dry to fully saturated condition. The overall effect of a fracture on the heat extraction capacity of the BFHEs unit was not significant, with a 5 mm wide fracture having an effect of no more than 2.5 %, even under the fully dry condition. However, there was a combined effect of multiple fractures, and for a deposit size of 900 × 7 × 80 m, ten 2 mm apertures fractures would results in a maximum reduction of geothermal extraction from BFHEs by 8527 GJ in 10 years, which was equivalent to the heat load of a 13,753 m2 building for one winter in the cold climate of China. [ABSTRACT FROM AUTHOR]

[Display omitted] • The study identifies higher pressure anomalies in the southeastern flank of the Huize fault-fold belt and the core of the Maoping belt, aligning with ore body locations. Zn2+ concentration is significantly higher in the SE flank of the Huize ore deposit and the NW flank of the Maoping deposit, revealing the impact of structural deformation on ore-forming fluid distribution. • Exploration potential is highlighted in specific areas, such as the core and southeastern wing of the Huize fault-fold belt and the core and northwestern wing of the Maoping fault-fold belt. Understanding the intricate relationship between fault-fold structures and ore body localization is paramount in economic geology. However, there is a lack of quantitative data on the influence of the geometry characteristics of faulted fold structures on the migration of ore-forming fluids. In this study, the differential ore-controlling characteristics of the steep flank of the anticline (Huize fault-fold belt,the ore body is located in the SE flank of the anticline) and the overturned flank of the anticline(Maoping fault-fold belt, the ore body is located in the NW flank of the anticline) were studied by using multi-physical finite element numerical simulation method. The findings of the study indicate that:(1) The local pressure anomalies in the core and southeastern flank of the Huize fault-fold belt is relatively higher than in comparable elevations elsewhere, while pressure anomalies in the Maoping fault-fold belt are concentrated in the core of the folds. (2) In the internal fault-fold belt of Huize, there is no significant temperature difference on either side of the folds. However, in the Maoping fault-fold belt, after reaching the core, heat predominantly transfers to the top pressure anomaly zone, resulting in noticeably higher temperatures in the northwest flank compared to the southeast flank. (3) Within the Huize fault-fold belt, ore-bearing fluids initially migrate along the fault, then move towards the core and SE flank upon reaching the mineralized strata. In contrast, within the Maoping fault-fold belt, ore-bearing fluids, after entering the layers, primarily migrate towards the core. (4) In the Huize ore deposit, the concentration of Zn2+ is significantly higher in the SE flank than in the NW flank, while in the Maoping deposit, the concentration is higher in the NW flank. The research results align with geological facts and provides valuable insights into the quantitative analysis of ore distribution controlled by the fault structure. This study provides crucial insights into exploring the control and influence of differential structural deformation on ore-bearing fluid migration, offering favorable exploration targets. [ABSTRACT FROM AUTHOR]

Predictive modeling of mineral prospectivity, which integrates diverse evidence of ore-forming processes based on an ore deposit genetic model constitutes a significant task in mineral exploration targeting. Descriptive deposit models suffer from overwhelming dependence on the explicitly mappable characteristics of a given deposit used to simplify the complex mineral system, but this hinders mineral prospectivity modeling. This study proposes a hybrid approach that combines numerical modeling with machine learning to predict mineral prospectivity. This approach first uses the numerical modeling method to provide more insights and better characterize a complex mineral system. These comprise implicit footprints such as singular stress deformation, heat transmission and fluid flux inherent in the transient geodynamics of ore genesis. The approach then applies a machine learning algorithm as a data-fusion tool to integrate the simulated evidence to minimize uncertainty in the predictive modeling of mineral prospectivity, which fundamentally results from an incomplete understanding of the targeted mineral system. Finally, we use the Fankou Mississippi Valley type Pb–Zn deposit as an example to illustrate the application of the proposed hybrid method. The prospectivity modeling result is critically compared with that of the spatial modeling based on descriptive deposit modeling by means of measures of accuracy, area under the receiver operating characteristic curve, and normalized density of prediction–area plot. It is shown that the overall performance of the prospectivity map predicted using a hybrid method is significantly improved. As such, this study demonstrates that a hybrid framework combining numerical modeling with machine learning provides a useful and novel way of predicting mineral prospectivity. The proposed hybrid method embodies a pioneering paradigm that integrates physics and data, assimilating ore deposit genesis models and reconnaissance data for the prediction of mineral prospectivity in support of exploration targeting. This approach can be implemented to enhance exploration information systems through the predictive modeling of mineral prospectivity in a unified computing and decision-making environment. The hybrid framework combining numerical modeling and machine learning for predictive mapping of mineral prospectivity. [Display omitted] • Here we apply numerical modeling in mineral prospectivity mapping (MPM). • Numerical modeling integrates ore deposit genesis models and exploration data. • Numerical modeling places physical and chemical constrains on MPM. • Numerical modeling-constrained MPM outperforms traditional MPM. [ABSTRACT FROM AUTHOR]

In this work, effective thermal conductivity (λEff) of fractured rock masses was numerically investigated. A two-dimensional Discrete Fracture Network (DFN) model of the fractured rock masses was established based on the statistic results of natural fracture development in a potential area for high level radioactive waste disposal in China. Steady state heat transfer processes in the fractured granite rock masses were numerically simulated using finite element method (FEM). The calculated λEff values of the fractured granite rock masses in dry and saturated conditions are 1.99 W/(m K) and 2.31 W/(m K), respectively. Compared with the thermal conductivity of intact granite [λIntact, 2.5 W/(m K)], the drop rates are 20.4% and 7.6%, respectively. Sensitivity analysis was conducted on the main model parameters including fracture density (FDensity), trace length (FLength), thermal contact resistance (FTCR), and λIntact. The results indicate the relation between λEff and three fracture parameters (FDensity, Flength and FTCR) can be fitted using power law or negative exponent functions with good consistency. When fracture network parameters remain unchanged, λEff is in linear positive correlation to λIntact. The slop of the fitted line is determined by the fracture network parameters. Due to the fact that distribution of generated fractures in different directions are quite uniform, λEff did not show significant difference in different directions. On the basis of the above-mentioned results, an estimation model was proposed for the determination of λEff of fractured rock masses using P21 (total length of fracture traces per unit area), FTCR, and λIntact. The proposed estimation model shows good consistency to the calculated results of FEM model. [ABSTRACT FROM AUTHOR]

Multi-span plastic tunnel greenhouse has widely been used in the cultivation of vegetables, fruits, and flowers. However, it is easily suffered from freezing damage to crops, particularly from cold waves in winter. In this study, an air thermal energy utilization system was developed with the fan-coil units to effectively control the thermal and humid environment in the shed. A field experimented was also performed on a two-span plastic tunnel in Wenzhou city of China during the cold wave from January 8 to January 13, 2021. The system was composed of fan-coil units, water reservoir, circulating water pump, supply and return water pipes, as well as control devices. The circulation of water in the system was utilized to collect and then store the surplus heat in the shed during the day, while finally released at night to heating the two-span plastic tunnel. In the collected phase, once the air temperature in the shed reached 15 ℃ on the day, or it was 5 ℃ higher than the water temperature in the water reservoir, the system was started until the air temperature dropped to 10 ℃, or it was 2 ℃ lower than the water temperature. In the released phase, once the outside air temperature was below 2 ℃ at night, or it was 4 ℃ lower than the water temperature, the system was started to operate until the air temperature reached 5 ℃, or it was only 2 ℃ higher than the water temperature. The collected and released performance of the system was evaluated using the collection and discharge heat, as well as heat flow, according to the change of water temperature in the experiment. The difference between water and air temperature was taken as the main influencing factor to analyze the heat flow in the collected and released phases. An exergy analysis of condensation dehumidification was also made during this time. The results showed that the system ensured the temperature inside the shed was 5.2-7.8 ℃ to protect crops from freezing damage, higher than that outside the shed in cold waves. The heat collection was 390.6-693 MJ, while the heat release was 361.2-609 MJ. The coefficient of performance (COP) of the system was 4.4-7.2, indicating quite remarkable energy saving. When the difference in water temperature increased by 1 ℃ during the operation of the system, the heat collection flow rate increased by 0.82 kW, while the heat release flow rate increased by 0.58 kW, indicating a larger heat transfer rate per unit time. In addition, the moisture absorption coefficient of the system was about 1.70 in the heat collected phase, due mainly to the presence of condensation and dehumidification. Meanwhile, the exergy efficiency tended to increase rapidly, up to 82.8%, as the temperature difference between water and air increased, indicating high energy utilization performance in the process of condensation and dehumidification. Nevertheless, the condensation and dehumidification gradually weakened until stopped, and concurrently the exergy efficiency decreased significantly, with the increase of water temperature. Consequently, the air thermal energy utilization system with fan-coil units can be expected to serve a safe, low carbon, and controllable heating technology. The finding can provide a potential application to ensure the safe production of multi-span plastic tunnels in winter [ABSTRACT FROM AUTHOR]

Summary: Closed type assembly leads to complicated core thermohydraulics which are significant for design and safety analysis in sodium‐cooled fast reactor (SFR). Most of the major phenomena can be dealt with by general parallel channel network and two‐dimensional model for inter‐wrapper flow (IWF) in system code transient thermal‐hydraulic code for analysis of SFR (THACS). A main deficiency left is the overestimation of inter‐assembly heat transfer effect due to lump temperature message that one‐dimensional assembly model can only provide. A methodology was thus developed to compute wall‐subchannel temperature for simulating energy transportation through duct wall. Intra‐assembly thermohydraulics were classified as two mechanisms and non‐dimensional parameter was introduced for characterizing each of them. Ratio between linear heat flux density through hexagonal wrapper surface and pin surface qw/p was employed to account for radial heat transfer. Flow redistribution effect arouse in mixed and natural convection was concretized by a importance symbol of buoyancy force, Richardson number Ri. Two criteria were also proposed for dividing flow state into three parts and specific model for each section was defined. Two validation cases against 3‐D computational fluid dynamics (CFD) simulation of China experimental fast reactor whole core and test data from plant dynamics test loop with direct heat exchanger experiment were performed with THACS. Noticeable improvement after incorporation of this model demonstrated its value in system analysis. Although the procedure for parameter computations is geometry related, this method can be reproduced to any type of assembly directly. [ABSTRACT FROM AUTHOR]

The NHR-200 reactor in China adopts the noncondensable gas self-stabilizing control and the noncondensable gas used for pressure stabilization control can weaken steam condensation heat transfer in the integrated steam-gas pressurizer. A condensation experimental system was established and the heat transfer characteristics of steam-nitrogen and steam-argon condensation under natural convection had been investigated. The pressure ranged from 0.516 to 5.10 MPa. The distributions of nitrogen and argon in the steam/gas mixture were obtained in the experiments, and the results showed that nitrogen and argon were evenly distributed in the steam under different pressure, respectively. The effects of heat transfer temperature difference had also been investigated and it is found that the total heat transfer coefficient difference had little influence on the total condensation heat transfer coefficient. However, the steam condensation heat transfer coefficient decreased with the increase of the degree of supercooling of the wall. The condensation heat transfer coefficient was reduced by approximately 0.11 kW/(m2·K) as the degree of supercooling of the wall changed from 14°C to 36°C. The condensation heat transfer coefficient also decreased with the mass/molar fraction of noncondensable gas increasing and a certain difference between the effect of the mass fraction of noncondensable gas and the effect of the molar fraction of noncondensable gas was discussed in this paper. [ABSTRACT FROM AUTHOR]

Composite hetero-structure wall is widely used for the north wall of solar greenhouse in China. A thermal stable thick layer in this type of wall can greatly weaken the heat storage capacity of the greenhouse wall. This study aims to improve the temperature of the thermal stable layer, and thereby promoting the heat storage capacity of north walls in a solar greenhouse. A new type of wall was proposed for the solar greenhouse with a flat Micro Heat Pipe Array (MHPA) wall or heat storage wall. The wall was made by bending the flat micro heat pipe array into a zigzag-shape while mixing the cement mortar to form an MHPA block. Then, the MHPA block and ordinary blocks were built into the MHPA wall. The evaporation section of the flat micro heat pipe array was placed on the inner surface of the MHPA wall, and the condensation section was placed inside the MHPA wall to achieve the purpose of enhancement heat transfer. Two small-scale greenhouse comparison test-benches were set up on site with the MHPA wall (named as MHPA greenhouse) and the ordinary block wall (named as ordinary greenhouse). The evaluation parameters included the temperature of the greenhouse wall, the daily heat storage/release of the wall, and the greenhouse environmental temperature. A systematic investigation was made to compare the characteristics of heat storage/release of the MHPA wall, and the effect of improving the greenhouse thermal environment on representative days. The results showed that the average internal surface temperature of the MHPA wall on typical sunny days (from 17:00 to 9:00 the next day) was 1.6-2.3 higher than that of an ordinary wall. From indoor to outdoor, the average ℃ temperature inside the MHPA wall for the 0-370 mm area along the wall thickness direction increased by 2.7-4.0 . During ℃ the heat storage period (from 9:00 to 17:00), the average environmental temperature of the MHPA greenhouse was 0.2-0.5 ℃ lower than that of an ordinary greenhouse, and the average ground surface temperature was 1.8-1.9 lower. During the heat ℃ release period, the average environmental temperature of the MHPA greenhouse was 1.2-1.5 higher than that of an ordinary ℃ greenhouse, and the average ground surface temperature was 0.6-1.0 higher. The MHPA wall can play the role of "peak ℃ cutting and valley filling" in the thermal environment of a greenhouse. The total daily heat storage of the MHPA wall was 8.92%-14.35% higher than that of an ordinary wall, and the total daily heat release was 2.24%-8.07% higher. In the heat storage and release rates of a wall on December 27, the maximum and average heat storage rates of the MHPA wall were 9.63 and 10.99% higher than those of the ordinary wall, and the maximum and average heat release rates were 9.23 and 5.60% higher than those of the ordinary wall, respectively. Moreover, the heat release rate of the MHPA wall was higher than that of an ordinary wall between 23:00 and 7:00 the next day, with an average increase of 11.53%. Therefore, the introduction of the MHPA wall into the wall of a solar greenhouse can effectively improve the heat storage and release capacity of the wall materials for a better thermal environment. These findings can provide a sound reference for the application of a flat micro-heat pipe array to the heat storage wall in a solar greenhouse. [ABSTRACT FROM AUTHOR]

• Compared coking and heat transfer of RP-3 in the corrugated and smooth channels. • Identified heat transfer deterioration in corrugated channel due to coke deposition. • Observed periodic wavy structures at fluid-solid interface in corrugated channel. • Obtained heat transfer correlation for RP-3 reacting flow in corrugated channel. Coking and heat transfer deterioration of supercritical aviation kerosene pose grave challenges to regenerative cooling of scramjet engines. In the present study, reaction and heat transfer characteristics of supercritical China aviation kerosene No. 3, RP-3 undergoing simultaneous pyrolysis and steam reforming reactions in a corrugated channel are numerically studied. Compared with reacting flow of RP-3 in the smooth channel, temperature and coke deposition are much lower in majority part of the corrugated channel. The maximum temperature difference between the smooth and corrugated channels is up to 300K. The maximum heat transfer coefficient in the corrugated channel is almost three times of that in the smooth channel under the same condition. However, low-velocity and high-temperature zones are formed near the corrugated micro-structures and cause coke accumulation and heat transfer deterioration along the flow direction of the corrugated channel. With the increase of wall heat flux, both temperature and velocity increase significantly in the corrugated channel. The conversion of RP-3 and formation of coke are also enhanced with increasing wall heat flux. Moreover, the total heat transfer coefficient first increases and then decreases with wall heat flux. The maximum total heat transfer coefficient increases from 4000W/m2∙K to 18,000W/m2∙K with wall heat flux increasing from 0.3MW/m2 to 1.8MW/m2. Periodic wavy structures are found at the interface between the corrugated micro-structure and the bulk flow, which is pronounced when wall heat flux is 1.3MW/m2 or above. With the increase of flow time, local turbulent kinetic energy decreases due to the interaction between the corrugated micro-structures and the wavy structures. The interaction between the corrugated structures and complex reaction and heat transfer leads to intersection of the distributions of temperature and coke in the smooth and the corrugated channels. An empirical heat transfer correlation formula is obtained as Nu =0.1 Re 0.65 Pr 1.94 for RP-3 reacting flow in the corrugated channel. The study provides better insight into interaction mechanism between chemically reacting flow and micro corrugated structures. Comparison of temperature, coke mass fraction and heat transfer coefficient between the smooth cooling channel and the corrugated cooling channel [Display omitted] [ABSTRACT FROM AUTHOR]

In Inner Mongolia, China, semi-arid grasslands have strong winds and radiation in spring, but it is unclear how grazing management influences the connections between aerodynamic and energy balance during this time. During spring, we conducted measurements of radiation, wind speed, and air temperature, for both grazed and grazing-prohibited grasslands. From these results it was found that the temperature gradient differential (ΔT = T 0.4m -T 2m) between the ground level (T 0.4m) and the high height (T 2m) is normally negative at night and positive during the day. Grazed grassland was found to have very few negative ΔT values. Albedo and ΔT were higher on the grazed grasslands, while net radiation and aerodynamic roughness (Z 0) were lower on the grazed grasslands. According to structural equation modeling (SEM), the grazing prohibited and grazed had no effect on the relationship between surface albedo, air temperature, and humidity. Z 0 in grazed grassland exhibited a substantial positive correlation with net radiation (Rn), but was not correlated with albedo. The Z 0 of the grazing-prohibited grassland exhibited a substantial negative correlation with albedo, but not with Rn, and Z 0 had a significant negative correlation with air temperature. These findings explain how grazing measures affect the vertical variations of surface heat in air. [Display omitted] • Quantify the thermal and aerodynamic properties over the grass. • The vertical temperature difference (ΔT) is smaller in the prohibited grassland. • Higher aerodynamic impedance and net radiation in the prohibited grassland. • Grazing affects the relationship between radiation, aerodynamics and air temperature. [ABSTRACT FROM AUTHOR]

• Heat transfer model of greenhouse cover under all operating conditions proposed. • The model can calculate the heat loss on the surface of greenhouse cover. • First study the long wave radiation relationship between crops and greenhouse cover. • First study on the influence of latent heat on the heat loss of the covering layer. • Considering the impact of greenhouse building layout on heat loss. The solar greenhouses in China are composed of gables on the east and west sides, north walls, and north and south roofs. The south roof is the main heat dissipation surface of the greenhouse. To quantitatively and comprehensively analyse the heat transfer characteristics and heat loss pathways of the south roof of a solar greenhouse, based on the actual usage of the greenhouse, the heat transfer of the south roof is classified into two working conditions: heat transfer of the transparent covering material (TCM) and heat transfer of the composite thermal insulation coating (CTIC). A theoretical heat transfer model of the covering layer of the solar greenhouse under all working conditions is constructed by applying the heat transfer theory. The model was tested using field test data from two areas different regions in China: Beijing and Lhasa. The results show good agreement between the simulated and measured values, the relative errors between simulated and measured values were 18.54% and 8.17%, respectively, with root mean square errors of 1.69 and 1.92. The model can comprehensively and accurately reflect the comprehensive heat transfer coefficient and heat loss changes of the south roof of the solar greenhouse. It can be used to analyze the proportion of heat loss caused by radiation, convection, and water vapor condensation. The analysis shows that condensation heat loss cannot be ignored during the winter night period. Measures such as covering the roof with plastic film and controlled irrigation can help reduce condensation heat loss. [ABSTRACT FROM AUTHOR]

The thermal conductivity of rock is an essential thermophysical parameter in geothermal engineering. Experiments have shown that when rock changes from an unsaturated to a saturated state, thermal conductivity can be increased by 50% at most. In this paper, the variation of thermal conductivity with saturation of 101 samples of six different rock types from Songliao Basin, Gonghe Basin, and Ordos Basin in China was measured in the laboratory. Correlations between saturation, porosity, internal structural characteristics of rocks and thermal conductivity were investigated. The results show that the effect of saturation on the thermal conductivity of rock increases exponentially with porosity. Based on three classical models and the relationship between porosity, saturation, and thermal conductivity, improved models and a fitted model of thermal conductivity are proposed. By comparing the improved models to the fitted model, the applicable scope of each model is obtained. The errors of each model are analyzed in detail. The average MAE value of the improved models is 0.405 and the average RMSE value is 1.207 over the applicable model scopes. The R 2 of the fitted model is 0.94. Compared with experimental data from literature, MAE values of the improved models and the fitted model are 0.040 and 0.003 respectively. Unsaturated rock with a single fracture heat transfer model is established by simulation. A thermal-Hydrological coupling model is used to simulate seepage heat transfer through fracture. The effect of variable thermal conductivity simulation is the best with the experimental value, and the MAPE value was 8.3%. This study fills a gap in available models of unsaturated thermal conductivity of rock, and provide theoretical support for the accurate calculation of heat transfer efficiencies in related geothermal engineering applications. • Theoretical saturation coefficient equation on thermal conductivity was proposed. • Three unsaturated thermal conductivity models were improved and verified. • Propose an empirical unsaturated model based on laboratory data. • The relationship between unsaturated model and rocks structure was revealed. [ABSTRACT FROM AUTHOR]

• A novel coaxial condensing heat pipe applied in the solar CCHP/PVT system was proposed. • Thermal, electrical and exergy efficiencies of the solar CCHP/PVT system were defined. • Proposed CCHP/PVT system has better performance in thermal and electrical efficiencies. • Current theoretical models and codes were well validated by former experiments and results. • CCHP/PVT was favored for solar exploitation, particularly in the solar energy poor regions. Heat pipes offer tremendous potential for utilization in the energy and construction industries due to their excellent heat transmission efficiency. The current study involved the development of a theoretical model for thermal transport in a coaxial condensing heat pipe (CCHP) connected with solar photovoltaic and thermal (PVT) systems. Subsequently, parameter studies were conducted to analyze their impact on system performance, including irradiation intensity, surrounding temperature, inlet temperature, mass flow rate and PV coverage factor. In addition, temperature variation, thermal and electrical conversion capabilities of the CCHP/PVT system on typical days were discussed utilizing meteorological conditions in Wuhan city as inputs for the analysis. Our findings showed that the morning is when thermal efficiency is at its highest across the seasons, and it remained between 50% and 55%. Compared to natural cooling and conventional heat pipe cooling, the CCHP/PVT system reduced the temperature of the PV panels by approximately 30.3% and 16.3%, respectively. The proposed CCHP/PVT system has a respectively 14.4% and 5.2% enhancement in thermal and electrical efficiencies in comparison with those conventional heat pipes. Here, theoretical results agree well with former published ones, with average errors of no more than 10%. Our parametric investigations were then put into practice to assess the overall performance and to serve as a theoretical foundation for later development. It was really beneficial to boost the efficiency of solar energy utilization in the Yangtze River, China, where solar potentials were relatively poor than north western China. [ABSTRACT FROM AUTHOR]

The natural fracture system exerts a significant influence on the physical and mechanical properties of rock masses. The heat transfer in fractured rock masses is much more complicated than that of intact rock due to the thermal contact resistance induced by natural fractures with varying size, aperture, roughness, and orientation. This work describes a method for determining the representative element volume (REV) of heat transfer and the 3D thermal conductivity tensor of fractured rock masses. The method is based on the element-wise averaging of temperature and heat flux, which can be obtained from a finite element solution to a steady state heat transfer problem with specific boundary conditions. A case study was conducted based on the geological data of a potential area for high level radioactive waste disposal in China. The results indicate that the size of heat transfer REV of the rock masses in the study area is approximately 18 m × 18 m × 18 m. 3D thermal conductivity tensor, the magnitudes and directions of the three principal thermal conductivities, and anisotropy of the fractured rock masses were obtained. Influences of main fracture parameters including density, disc diameter, and thermal contact resistance on the heat transfer characteristics were investigated. The research results in this work can provide a better understanding of the discontinuous heat transfer processes in fractured rock masses and their homogenization methods. [ABSTRACT FROM AUTHOR]

This study is aimed at carrying out investigations on a domestic gas field, located in Yanchang, China, with a view to optimize the natural gas purification process. The main objectives of this work are (i) to reduce the natural gas purification system's energy consumption and (ii) improve the existing purification levels. Process simulations were carried out using Aspen Plus™ software, and a comprehensive technical and economic analysis was carried out. The single-factor sensitivity analysis method was used to determine the parameters of absorption, such as the reflux ratio and number of stages. The heat transfer process was analyzed using the energy-saving method of the energy system, and a modified process was recommended. The optimization results show that the recommended system has better purification performance, the comprehensive energy consumption is effectively reduced, and the energy efficiency is improved by 9%. [ABSTRACT FROM AUTHOR]

In consumer fireworks, various functions of chemicals create an energetic reaction with a type of colored light, smoke, heat, and the sound to achieve the pyrotechnic effects. Fireworks mixtures may be highly sensitive to external disturbances such as ignition sources, temperature changes, shocks, friction, and static electricity. Approximately 95% of fireworks are imported from China by ocean shipment, taking 4 days to a week to Taiwan. The prediction and assessment for the nth-order reaction, and thermokinetic parameters from thermal safety model for fireworks and pyrotechnic compositions were investigated. This study showed which reaction intensity of the propellant as water was added. It can be seen from the results that water will affect the thermal hazard of propellant. Moreover, the novel findings indicated that the water increased the thermal hazard of the propellant and consequently increased the risk for launching a degradation. Based on the heat transfer theoretical models, the time to maximum rate and time to conversion limit were extrapolated for consideration and discussion. [ABSTRACT FROM AUTHOR]

In China, the energy policy of switching charcoal heating to electric heating is pushing hard. Radiant floor heating system (RFHS) with air-source heat pump system is considered to be a suitable scheme for energy retrofit. A new type of lightweight RFHS with the aluminum layer is put forward in this article, which has the benefit of lowering the supply water temperature by enhancing the heat transfer performance and homogenizing the floor surface temperature distribution. The theoretical model of the new lightweight RFHS is built and solved by the Matlab program. Experiments are conducted to study the thermal performance of the RFHS and verify the theoretical model. The effects of supply water temperature and water flow velocity on the thermal performances of the new RFHS are studied. Then, the effects of aluminum layer on the heat transfer performance of the new system are researched. Finally, comparative research of the new lightweight RFHS and traditional heavy RFHS is carried out. The results show that the average floor surface temperature, heat transfer rate, and annual exploitation cost of the new RFHS are all better than the traditional one. [ABSTRACT FROM AUTHOR]

Solar greenhouse is a typical greenhouse without any additional heating system, which has developed rapidly in Northern China. However, due to the construction quality, management methods, especially the long-term use and other factors, there are usually different degrees of thermodynamic disfigurements in the envelop enclosure of solar greenhouse. The purpose of this study was to investigate the influences of thermodynamic disfigurement on the temperature distribution and convective heat transfer of solar greenhouse. In this study, the east and west compartments of a typical solar greenhouse which is located in Yangling, China (108°4'E, 34°16'N) were tested. The air temperature of each compartment was collected using temperature recorders, and the thermal infrared images of different compartment envelopes were obtained by a thermal infrared imager on a typical cloudy day. Convective heat transfer coefficients and heat flux densities of different compartment envelopes in the solar greenhouse were calculated. The results showed that the temperature difference can be displayed in the thermal infrared images of compartment envelopes, the surface temperature of the front roof was the lowest, followed by the back roof, the wall surface temperature was the highest. The minimum average surface temperature of the front roof in the eastern compartment was only 3.8°C, which was 6.8°C and 9.2°C lower than the average surface temperature of the back roof and back wall, respectively. The surface average temperature of thermodynamic disfigurements located at the bottom of the south side in the front roof of the eastern compartment, whose area accounted for 16.5% of the total front roof in the eastern compartment, was only 5.4°C. Compared with non-thermodynamic disfigurement, the average convective heat transfer coefficient and heat flux density of thermodynamic disfigurements in the front roof of the eastern compartment were increased by 20.3% and 110.3%, respectively. The average air temperature in the eastern compartment was 3.5°C lower than the average air temperature in the western compartment of the solar greenhouse. Construction of brick wall at the bottom of the south side of the front roof in the solar greenhouse helped to increase the inner surface temperature of the front roof, with an average temperature rise of 6.2°C, and reduce the area of thermodynamic disfigurement, which only accounted for 2.6% of the total front roof in the western compartment. The average surface temperature of thermodynamic disfigurements mainly caused by the entry and exit door in the wall of the eastern compartment was only 9.8°C, which was lower 3.2°C than the average temperature of non-thermodynamic disfigurement of the wall. Thermodynamic disfigurement helped to increase heat loss. The weighted average proportion of thermodynamic disfigurement in the western compartment was 2.1%, while that of thermodynamic disfigurement in the eastern compartment was 10.7%. The thermal insulation performance of the western ompartment envelope in the solar greenhouse was better than that of the eastern compartment envelope. [ABSTRACT FROM AUTHOR]

Summary: Waste heat recovery helps reduce energy consumption, decreases carbon emissions, and enhances sustainable energy development. In China, energy‐intensive industries dominate the industrial sector and have significant potential for waste heat recovery. We propose a novel waste heat recovery system assisted by a heat pipe and thermoelectric generator (TEG) namely, heat pipe TEG (HPTEG)，to simultaneously recover waste heat and achieve electricity generation. Moreover, the HPTEG provides a good approach to bridging the mismatch between energy supply and demand. Based on the technical reserve on high‐temperature heat pipe manufacturing and TEG device integration, a laboratory‐scale HPTEG prototype was established to investigate the coupling performances of the heat pipes and TEGs. Static energy conversion and passive thermal transport were achieved with the assistance of skutterudite TEGs and potassium heat pipes. Based on the HPTEG prototype, the heat transfer and the thermoelectric conversion performances were investigated. Potassium heat pipes exhibited excellent heat transfer performance with 95% thermal efficiency. The isothermality of such a heat pipe was excellent, and the heat pipe temperature gradient was within 15°C. The TEG's thermoelectric conversion efficiency of 7.5% and HPTEG's prototype system thermoelectric conversion efficiency of 6.2% were achieved. When the TEG hot surface temperature reached 625°C, the maximum electrical output power of the TEG peaked at 183.2 W, and the open‐circuit voltage reached 42.2 V. The high performances of the HPTEG prototype demonstrated the potential of the HPTEG for use in engineering applications. [ABSTRACT FROM AUTHOR]

To promote the full combustion efficiency of a body cremation furnace during cremation, the temperature and velocity of cremation furnace in the process of body combustion are simulated by finite element model. Firstly, the simplified finite element analysis model of cremation furnace and its finite element software is introduced in this study, and then the flow model, heat transfer model, and combustion model needed in the heat transfer process are described. According to the requirements of the finite element model, the mesh generation process of the cremation furnace model and the numerical solution method are presented. Finally, the model used in this study is verified by the test and simulation results. The results show that the method is reliable. Besides, the design parameters of the temperature part and the combustion speed part of the furnace under six different working conditions are analyzed to further optimize the structure of the furnace. The results of this study provide a good theoretical basis for cremation equipment and promote the development of China's cremation industry. [ABSTRACT FROM AUTHOR]

To match for the different temperature of the geothermal resource and strengthen the flexibility of organic Rankine cycle, a variable capacity power generation superstructure based on flash and organic Rankine cycle for geothermal energy was proposed. A combined flash-binary experimental prototype is newly established to investigate thermodynamic performance both on system and equipment in this paper. Pressured hot water is adopted as the extensive worldwide existed hydrothermal geothermal resource, eliminating the influence of the used heat transfer oil on evaporating process. The experimental results show that there is an optimal mass-flow rate of R245fa under the condition of different heat source temperature. Flash and binary power subsystem dominate the flash-binary power system, respectively, when the heat source temperature is 120 °C and 130 °C. The isotropic efficiency of modified compressor just between 0.2 and 0.25. The power output of per ton geofluid are 0.78 kWh/t and 1.31 kWh/t, respectively, when the heat source temperature are 120 °C and 130 °. These results will predict the operation data of flash-binary power plant driven by the low-medium temperature geothermal water for construction in western of China. [ABSTRACT FROM AUTHOR]

Soil moisture (SM) feedback on climate variables especially temperature is an important aspect in land-atmosphere coupling. Based on the Global Land Data Assimilation System (GLDAS) V2.0 SM data and the gridded observational temperature data, we statistically analyze the thermal feedback of SM over North China (NC). The results show that SM exerts a decreasing trend under the background of evident warming over NC, inducing a decadal enhancement of SM feedbacks on the local temperature and extreme hot events. The SM feedback contributes 6% of the total air temperature variation during 1961–2012, while it reaches 36% after the regional warming during 1994–2012. Such SM affecting temperature is mainly reflected in its feedback on daily maximum temperature, which is also intensified during the warm period. The decadal intensification is also found in the feedback of SM on hot extremes. Further analyses show that the abnormal changes of the latent and sensible heat fluxes caused by the SM anomaly are the main reasons that affect the thermal conditions. Besides, the rising Bowen ratio indicates that upward thermal transfer on the land surface is enhanced in recent years, which suggests that the atmosphere is more sensible to the abnormal heating on the ground. This consequently translates into the decadal intensification of the local thermal feedback of SM in summer over NC. [ABSTRACT FROM AUTHOR]

Oviraptorosaurs, a group of non-avian theropod dinosaurs from the Cretaceous of Asia and North America, left behind the most abundant and informative fossil evidence of dinosaur reproductive biology. Previous studies had suggested that oviraptorosaur reproductive biology represents an intermediate stage and exhibited unique modern avian traits. For instance, the adult-associated clutches were predominantly considered as evidence for brooding/thermoregulatory contact incubation (TCI) behaviors, whereas the hypotheses of laying or protection were neglected. Despite numerous oviraptorid egg clutches uncovered from China and Mongolia, their nest architecture and clutch arrangement were rarely investigated in detail. Here we present a comprehensive reconstruction of an oviraptorid clutch based on five new oviraptorid clutches from Jiangxi Province, China. A detailed examination of the new clutches reveals a partially-open oviraptorid nest that contains 3-4 rings of paired eggs (more than 15 pairs total) whose blunt end points toward the center devoid of eggs at an angle of 35-40°. Our detailed three-dimensional reconstruction indicates that the oviraptorid clutch has a unique architecture unknown from extant bird clutches, implying an apomorphic nesting mode. Such a unique nest architecture further contradicts the TCI hypothesis in oviraptorids, hindering sufficient heat transfer to the inner (lower) ring(s) of eggs. Moreover, the size of the new oviraptorid clutches (>30 eggs) is significantly larger than that of the adult-associated clutches (<22 eggs), raising the alternative hypothesis that the adult-associated clutches were uncompleted. This clue thus supports the hypothesis that the clutch-associated oviraptorid adults possibly represent females after an oviposition before a catastrophic sandstorm/flooding burial. [ABSTRACT FROM AUTHOR]

• A constant-temperature thermal response test was proposed and demonstrated. • The new concept enables simultaneous heat injection and extraction tests. • A test data analysis method was developed based on the finite line source model. • Ground thermal conductivity was evaluated for both heat injection and extraction. • Convective effect enhanced ground heat transfer when heat injection was involved. Getting an accurate estimate of site-specific ground thermal conductivity from thermal response tests (TRTs) is crucial to the efficient and sustainable use of ground source heat pump systems. In a conventional TRT, the ground thermal conductivity is estimated by perturbing the ground with a positive heat injection and the response is measured in time. Despite the simplicity, the conventional TRT does not take into account the ground thermal response to cooling pulses. This may lead to mode-biased estimation due to the presence of natural convective effect. To address the problem, a constant-temperature TRT that comprises simultaneous heat injection and extraction was proposed. A test data analysis method was developed based on the finite line-source model. On this basis, a very first field test was performed in Taiyuan, China, demonstrating the use of the proposed TRT concept with full-scale measurements. Results show that, in the case of this field test, the ground thermal conductivities derived separately from heat injection and heat extraction are 1.83 W/(m K) and 1.65 W/(m K), respectively. The significant difference (10.9%) indicates that when heat injection is involved, the natural convective effect has enhanced ground heat transfer to increase the conductivity estimate. Thus, as compared to the conventional approach, the use of the proposed TRT can improve the characterization of the ground thermal response and conductivity. Relevant results and the test protocol reported in this study will be useful in providing the background information for this technology to be adopted in the ground source heat pump industry. [ABSTRACT FROM AUTHOR]

• In-depth interpretation of the thermal-hydraulics characteristics of flow blockage events in the fuel assembly. • Enhanced models for the wire-wrap spacer and convective heat transfer. • Good agreement between predictions and experimental data on velocity and temperature distributions downstream of the blockage. • Analysis of the impact of blockage location and size on coolant and cladding temperatures in fuel assembly of CEFR. The subchannel code ATHAS-LMR has been improved for analyzing thermal-hydraulics characteristics of flow blockage events in the fuel assembly of a sodium-cooled fast reactor (SFR). Based on the in-depth study of the phenomenon of flow blockage and combined with the characteristics of fast reactor assembly, enhanced models for the wire-wrap spacer and convective heat transfer have been added to account for changes in transverse flow in the presence of blockages. And appropriate transverse mixing and local resistance model are also implemented in ATHAS-LMR-FB. The improved code has been assessed against experimental data obtained at adiabatic and diabatic conditions in SFR assemblies with simulated flow blockages. Good agreement between predictions and experimental data on velocity and temperature distributions downstream of the blockage has been observed. Comparison of predictions of various analytical tools have also been performed. Predictions of the improved ATHAS-LMR code are shown to be compatible with those of other analytical tools. An in-depth analysis of effects of location and size of blockage has been carried out for the fuel assembly of the China Experimental Fast Reactor. Boiling has been predicted to occur for blockage ratios greater than 55.61% at the central location of the fuel assembly. Peak cladding and coolant temperatures are predicted at the axial location 70% of the rod length (just downstream of the maximum local power position of the non-uniform axial power profile). [ABSTRACT FROM AUTHOR]

Anaerobic fermentation is an important technical way to deal with organic wastes in China. However, in the process of treating organic wastes under high load conditions by anaerobic fermentation technology, it is easy to cause anaerobic fermentation operation unstable and the efficiency of organic waste treatment is not high due to the inhibitory substances such as the high concentration of organic acid and ammonia nitrogen. Biochar is a multi-aperture carbonaceous material formed by high-temperature pyrolysis of biomass materials under the anaerobic or anoxic conditions. Biochar has many excellent properties, such as the high specific surface area, good conductivity, mass transfer and heat transfer performance. At the same time, biochar also contains a lot of ash, and the abundant ash contains a lot of elements such as calcium and magnesium, which makes the biochar have good adsorption and ion exchange performance. As an additive for anaerobic fermentation, it can effectively improve the pH value, alkalinity and the acid buffer capacity of the anaerobic fermentation system, and alleviate the inhibition of the excessive production of methane by the volatile fatty acids during the lag period. It can cause the adhesion of microorganisms and had a certain microbial carrier effect. Addition of biochar can effectively solve the problems of the low efficiency of gas production and unstable fermentation in current anaerobic fermentation, and biochar is now widely used in anaerobic fermentation technology research. In recent years, the research status of domestic and foreign showed that biochar could effectively strengthen anaerobic fermentation under certain conditions and improve the treatment efficiency of organic wastes in anaerobic fermentation process. However, for the biochar-enhanced anaerobic fermentation technology approach, there were still no systematic reviewed and reported. In this paper, the chemical composition, surface pore structure, key factors of surface functional groups and important ways of biochar-enhanced anaerobic fermentation technology of biochar materials were systematically analyzed and summarized. Based on the physical and chemical properties of biochar materials, biochar was described. For example, the effects of different types, different particle sizes and different amounts of additive biochar on anaerobic fermentation. And the intensive pathways of anaerobic fermentation technology mainly included: Biochar could effectively improve the buffer capacity of the system, it had a certain microbial carrier function, and it could strengthen the interspecific electron transport of microorganisms. On this basis, the focus of research on anaerobic fermentation technology of organic wastes in the future was proposed. At the same time, it also provided support for the in-depth development of biochar enhanced anaerobic fermentation technology. [ABSTRACT FROM AUTHOR]

• A design analysis code for sodium heated OTSG is developed based on the power mesh method. • The code is verified with various design data both of integral type and modular type OTSGs. • The influence of tube diameter on heat transfer capacity has been analyzed by the code. Sodium heated once-through steam generator (OTSG) is a critical component of Sodium cooled Fast Reactor (SFR). It is a counter current heat exchanger. It transfers heat from hot sodium to water. Therefore, the steam generator is a necessity for the operation of the plant. However, due to the phase change exists in water side, it becomes challenging to design a steam generator for SFR. After the successful construction of CEFR (China Experiment Fast Reactor), a power-up demonstration SFR is being developed in China. For the design and analysis of the steam generator of the demonstration SFR, a thermal hydraulic Design Code of Once-through Steam generator for Sodium cooled fast reactor (DeCOSS) has been developed based on the movable mesh method. The DeCOSS code has been benchmarked based on the design data of OTSGs reported. The tube lengths and temperature distributions calculated by DeCOSS showed general agreements with published data. The influences of tube diameters on heat transfer capacity have been analyzed. The results indicated that the heat transfer capacity is determined by the thermal resistance of tube wall under the condition of fixed heat transfer coefficient of water side. In addition, under the same flow area of water and sodium, the heat transfer capacity could be enhanced by decreasing the tube diameters with constant tube wall thickness. Hence, the code can be utilized to do the sensitivity analyses and optimum thermal design of OTSGs. Moreover, it can support the design work of once-through steam generator of SFR. [ABSTRACT FROM AUTHOR]

• Numerical inversion analysis of centrifuge test was conducted. • A rigorous coupled heat-moisture-stress numerical model was proposed. • The major factors on axial stress response of buried pipe were analyzed. • Stress prediction model employing SVR was proposed and verified. Large diameter crude oil transmission pipelines in unstable permafrost areas have been put into operation in China in recent dozen years. The perennial positive temperature operation of buried heating transmission pipelines leads to freeze–thaw of the soil around pipelines, and the axial stresses generated by thawing settlement of permafrost may induce fracture failure of weld crack. However, there are many shortcomings in existing frozen soil thawing settlement analysis and pipeline stress assessment methods, which makes it difficult to accurately analyze and predict the axial additional stress of pipelines induced by thawing settlement. Based on heat conduction and permafrost thawing consolidation settlement theory, numerical inversion analysis of centrifuge test was conducted to verify the accuracy of the finite element method. The key influencing factors such as wall thickness, insulation layer thickness, buried depth of pipe, and length of thawing settlement zone on the axial stress and strain state of buried pipeline under the condition of double pipe operation of Mo-da line were investigated. The results show that: Pipeline with an insulation layer, larger wall thickness and smaller buried depth is beneficial to improve the bearing capacity of buried pipeline under thawing settlement of permafrost. The axial stress varies nonlinearly with the increase of the thawing settlement zone length. Based on support vector regression (SVR) model, the axial stress prediction model of pipe crown and invert at different positions in the thaw settlement area was proposed and verified by field monitoring data of buried pipeline. The relative error between the prediction results and the field monitoring results is less than 15 %. This study can provide some theoretical support for the structural design of pipelines in thaw settlement area. [ABSTRACT FROM AUTHOR]

• Two 1:4 geometrical scaled models with fixed and free boundary conditions under a cyclic temperature test were conducted. • The heat transfer under the fixed boundary condition could be accelerated from the track slab to the CAM layer. • The heat transfer models of two scaled models are verified by the temperature and stress results of cyclic temperature tests. • The positive and negative cyclic temperature zone could produce a larger interlaminar displacement between track slab and CAM. • The large cyclic temperature amplitude in slab strack leads to larger internal temperatures, stresses and vertical displacement. As a kind of multi-layer concrete structure, thermal responses China Railway Track System type II (CRTS II) slab track subject to diurnal temperature variation could significantly affect its long-term structural performance of slab track, and ultimately the safety of the high-speed train. However, the thermal responses of the bridge supported longitudinal CRTS II slab track have not been fully understood due to the complex of the structural system. The purpose of this study is to systematically investigate the thermal responses of the bridge supported CRTS II slab track system by conducting experimental testing on the scaled models with different boundary conditions in conjunction with theoretical modelling. The results show that the boundary conditions of the CRTS II slab track have a significant influence on thermal responses of the slab track. For example, the heat transfer from the track slab to the cement asphalt mortar (CAM) layer could be accelerated under fixed boundary condition. In addition, the longitudinal thermal stress within the CRTS II slab track under the fixed boundary condition is higher that under free boundary condition. Importantly, it indicates that the vertical thermal gradient in the CRTS II slab track induced by the diurnal temperature variation could lead to the damage of the interface between the track slab and CAM. [ABSTRACT FROM AUTHOR]

The Experimental Advanced Superconducting Tokamak (EAST) had been under major upgrading from 2020 to 2021 in China. In this campaign of major upgrading, the new lower tungsten divertor is successfully installed to achieve the targets of long pulse and high β H-mode plasma operation. High temperature and high pressure Divertor primary heat transfer system (DIV PHTS) is also developed to remove the plasma deposition heat load on the Divertor. This paper presents a description of the design and construction of DIV PHTS for EAST Tokamak. Starting from the requirements specified in the Technical Specifications of DIV PHTS, the process to meet the Divertor cooling and baking requirement is designed and validated by the supported thermal-hydraulic analysis. Then, the piping stress analysis under different types of load combinations is performed to verify the structural design requirements. General layout design is also performed based on the component requirement and the allocated space in the EAST Tokamak hall. Finally, the procurement and test of the system main equipment is also given. [ABSTRACT FROM AUTHOR]

In the present study, a continuous thermoelectric power generation device (CTEG RC) has been fabricated by combining the recently proposed radiative cooling paint with a commercially available thermoelectric generator (TEG) to achieve continuous power generation throughout the day. The CTEG RC has been modeled and the results have been verified through experiments, and then the effects of structural and environmental parameters on the performance of the CTEG RC have been discussed in detail. The annual performance of the CTEG RC has been evaluated for five different weather conditions (five cities in China) based on the established model. It has been shown that an annual power generation of 241.46 Wh/m2-423.86 Wh/m2 can be achieved for the applications of the CTEG RC in the five climate zones of China based on an optimal area ratio of 11 for the radiative cooling module to the TEG. • CTEG RC is proposed by integrating a radiative cooling paint and a TEG. • Heat transfer process of CTEG RC is modeled and verified with experiments. • Optimal area ratio of the radiative cooling module to the TEG is obtained. • Annual power generation by CTEG RC for several cities in China is estimated. [ABSTRACT FROM AUTHOR]

Highlights • An over-temperature protection system has been designed for the spallation target in CiADS system to prevent the granular target from abnormal irradiation by the accelerator's beam. • In order to evaluate the validity of the protection functions, the spatio-temporal variations of the target temperatures have been investigated with the heat transfer model. • The simulation results can be summarized as follows. (1) Beam scanning can be used to avoid very high temperature at the target center. (2) The granular blockage can also be detected by measuring the temperatures in the four directions. (3) Beam deviation can be detected by comparing the temperatures in the four directions. • Finally, over-temperature protection logic was designed, the accelerator and reactor in CiADS are shut down urgently by removing power from the ECR ion source, allowing the accelerator to urgently shut down its beam. Abstract In an accelerator driven sub-critical system (ADS), a spallation target is irradiated by high-power proton beam to drive a sub-critical reactor. To continuously produce very intense neutrons, it is very important to prevent the unsafe operation of the target. This paper reports an over-temperature protection system for the spallation target in China initiative ADS system, where tungsten granules in the target container are used as both coolant and target materials. In order to protect the target from abnormal irradiation by the accelerator's beam when the granules are blocked or when the beam deviates from the target center, 12 sets of thermocouples are mounted inside the target container to monitor the target temperature. To evaluate the protection functions of these thermocouples, the heat transfer model of particles has been employed to investigate the spatio-temporal variations of the target temperatures when tungsten granules stay static in the target. The simulation results indicate that the temperatures of the thermocouples increase with the irradiation time and the granular blockage can be detected by analyzing the temperatures of these thermocouples. On the other hand, when the beam center deviates from the target center, the azimuthal distribution of the target temperature becomes non-uniform, and the temperature of the thermocouple close to the beam center increases faster. Finally, in the monitoring system for the over-temperature protection, 12 thermocouples divided into 3 groups which are fixed within the target in the upper, central and lower parts of the target, and 4 thermocouples in each group are located in four directions of east, south, west, and north. If two or more channels of four directions in one group exceed the set point, the protective function of granular blockage will be initiated; if two or more channels in one direction are greater than the set point, the protective function of beam deviation will be triggered. [ABSTRACT FROM AUTHOR]

• A PVT collector with a roll-bond absorber is designed for rural home application. • Thermo-laminating is a novel and convenient method for PV-absorber connection. • The validated PVT model can simulate the roll-bond PVT performance accurately. • The model is available for predicting the dynamic performance of PVT systems. This paper mainly investigated the performance of a low-cost roll-bond water-type photovoltaic thermal (PVT) collector from both experimental and modelling approaches under the climatic conditions of Sichuan Basin of China. The design and manufacturing process of the PVT prototype adopted the available commercial PV panels for convenience and for reducing the manufacturing cost. The experiment measured all the main properties of the developed PVT module. The excellent heat transfer performance of its roll-bond absorber plate was also validated by outdoor steady-state tests. Then, the steady-state numerical models were used to simulate the performance of the PVT prototype in TRNSYS. By comparing the simulation and experimental results, two robust models were selected which have their own advantages in charactering the thermal and electrical properties of the PVT collector. Through validating the numerical models with experimental data, the deviation between the simulated and the measured values was further reduced. In addition, a complete photovoltaic thermal–domestic hot water (PVT-DHW) system with such PVT collectors was developed in TRNSYS, by which the annual system output and efficiency were predicted and analysed. [ABSTRACT FROM AUTHOR]