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• Developed a fast and high-fidelity prediction method based on CFD and POD coupling. • High-fidelity thermal fields and parameters prediction with maximum deviation 3.04 %. • The POD demonstrates significant CPU time savings of 99.87 % compared with the CFD. • The MLR model based on POD dataset provides functions with maximum deviation 7.9 %. The thermal performance of the reactor pressure vessel (RPV) insulation structure plays a crucial role in ensuring the operational safety of the reactor. In this study, a fast and high-fidelity prediction system is proposed, which is based on the snapshot ensemble generated by the computational fluid dynamics (CFD) method and incorporates proper orthogonal decomposition (POD) as its core component to predict the heat transfer performance of the RPV insulation structure. The proposed thermal-field prediction system is employed to examine the impacts of air inlet temperature, mass flow rate, and RPV outer wall temperature on the thermal performance parameters: average heat flux q out and temperature T out of the RPV insulation outer wall, as well as the maximum local temperature T max of the concrete pit inner wall. The POD predictive results showcase that the maximum relative deviations of q out , T out and T max for eight sets of off-design cases are 2.25 %, 3.04 %, and 2.37 %, respectively. Meanwhile, the maximum values of q out , T out and T max are 90.13 W · m − 2 , 44.69 ℃, and 87.51 ℃, respectively. They are all less than their prescribed limits. The field distributions of heat flux and temperature in off-design cases exhibit consistency between the CFD and POD methods. Notably, in comparison to the CFD simulation method, the POD method capturing more than 99.9 % energy demonstrates significant computational time savings for 99.87 %. Moreover, a multivariate linear regression (MLR) model for thermal performance parameters is established based on the POD prediction datasets. The results indicate that the maximum relative deviations between the POD and MLR methods in predicting q out , T out and T max for the 72 sets of test cases are 5.1 %, 7.9 % and 7.1 %, respectively. Meanwhile, 99.99 % CPU time is reduced for MLR model compared with CFD method. Obviously, the predictive system showcases excellent accuracy and efficiency in forecasting. [ABSTRACT FROM AUTHOR]

A full-knowledge of the temperature distribution in a data center is crucial for the design and operation to avoid thermal failure. However, it is a great challenge to conduct full-field simulations using the computational fluid dynamics/heat transfer (CFD/HT) method due to the unacceptable computational cost caused by the multi-scale structure of data centers. In this paper, a novel multi-scale model based on POD and CFD coupling is proposed to predict the thermal and fluid characteristics in data centers from room scale to chip scale. The temperature and flow fields in an air-cooled data center are predicted and analyzed under the scales of room, server, IGBT and chip. Based on the CFD results of Room-Server level, 16 sets of design cases' temperature fields for Server-IGBT level are compared using the POD and CFD methods, which shows that the maximum average absolute deviation and average relative deviation are 0.004 °C and 0.59%, respectively. Subsequently, three sets of off-design cases for Server-IGBT level and IGBT-Chip level are predicted using the aforementioned methods, yielding the maximum relative deviation 7.21% and 0.98%, respectively. The salient outcome is the remarkable 175-fold reduction in CPU processing time achieved with the POD model compared to traditional CFD simulations. [ABSTRACT FROM AUTHOR]

Purpose: To present the detailed implementation processes of the IDEAL algorithm for two-dimensional compressible flows based on Delaunay triangular mesh, and compare the performance of the SIMPLE and IDEAL algorithms for solving compressible problems. What's more, the implementation processes of Delaunay mesh generation and derivation of the pressure correction equation are also introduced. Design/methodology/approach: Programming completely in C++. Findings: Five compressible examples are used to test the SIMPLE and IDEAL algorithms, and the comparison with measurement data shows good agreement. The IDEAL algorithm has much better performance in both convergence rate and stability over the SIMPLE algorithm. Originality/value: The detail solution procedure of implementing the IDEAL algorithm for compressible flows based on Delaunay triangular mesh is presented in this work, seemingly first in the literature. [ABSTRACT FROM AUTHOR]

In a core meltdown accident, the reactor pressure vessel (RPV) insulation plays a significant role in the flooding process of the reactor cavity. The research on the function role of RPV insulation has attracted lots of attention whereas there are relatively few studies on heat transfer characteristics. Besides, the majority of previous studies on RPV insulation adopted a down-scaling or partial model instead of the entire model to decrease computational complexity. In this paper, a mesh assembly method is proposed to generate block-structured meshes and the heat transfer characteristics of the RPV insulation is carried out. Then a partial validation model has been verified against the experiments results. In addition, the effects of the air supply temperature, flow rate, and insulation installation gap on the overall model heat transfer performance of RPV insulation are investigated. The results demonstrate that the mean temperature of the insulation's outer wall (42.92 °C), the local temperature of the concrete (73.85 °C), and the heat flux of the insulation's outer wall (93.48 W ⋅ m ‐ 2) are less than their limit values of 60 °C, 95 °C, and 235 W ⋅ m ‐ 2 , respectively. And the heat leakage from the supports accounts for over 90% of the total heat dissipation. [ABSTRACT FROM AUTHOR]

Abstract Ammonia-water absorption-resorption heat pump (ARHP) is a promising technology for promoting efficient utilization of low-temperature thermal for space heating. This paper proposes a novel unbalanced ARHP cycle by replacing the condenser and evaporator in the conventional absorption heat pump (AHP) cycle with a high-pressure absorber and a low-pressure generator, respectively. The proposed cycle can work just depending on the concentration difference of ammonia-water solution under different pressure levels. A numerical model has been developed to investigate the feasible high-pressure/low-pressure (P H / P L) values to effect the thermodynamic cycle. The cycle's coefficient of performance (COP) under different P H / P L pair values and other given working conditions are studied. The maximum COP is 1.550 and the corresponding optimum P H / P L pair to effect the cycle is 1.40 MPa/0.38 MPa at a heat source temperature of 95 °C. When P H / P L pair value is 1.40/0.38 MPa, heat supply temperature of 44.5 °C and COP value of 1.331 can be obtained, which can basically meet the temperature demand of building floor heating. In addition, effects of different P H / P L pair values on solution circulation ratios and vapor discharge scopes of generators are discussed. It is concluded that the ideal P H / P L candidates yield large concentration difference between the inlet and outlet of generators and absorbers. Meanwhile, the solution circulation ratios of the two generators at ideal P H / P L pairs are acceptable values between 2.0 and 12.0. The cycle can work when the ambient temperature is above −7.5 °C and the driving heat source temperature is larger than 85 °C, which is potential in efficient utilization of commonly used stationary solar collectors for winter heating. Highlights • An unbalanced absorption-resorption heat pump cycle was developed. • Mathematical model was developed to explore feasible inner operation pressures. • Effects of different operation parameters on the cycle's COP were analyzed. • Performance was compared with that of conventional absorption heat pumps. • COP of the whole solar driven space heating system was investigated. [ABSTRACT FROM AUTHOR]

Winemaking is a global industry that needs to advance with the times taking into consideration the developing drinking needs, tastes of human beings and the growing demand on the world's renewable energy sources. Climate changes have brought nowadays challenges of energy requirements, subsequent emissions and the detrimental effects facing the winemaking industry and mankind. Given its energy requirements, concomitant emissions and the pernicious effects, winemaking industry should bear the brunt of improving energy utilization efficiency and promoting the development and adoption of renewable energy utilization technologies. Various kinds of renewable energy are being used in winemaking industry worldwide, especially solar energy in the form of solar thermal and solar photovoltaic, which offer a clean solution to fossil fuels shortage and pollutant emissions caused by or involved in winemaking processes. The objective of this paper to present challenges facing solar energy utilization in winemaking by summarizing the status of solar energy utilization in wineries worldwide, by outlining the current solar energy profile of these wineries and by stressing the existing and potential application aspects of solar energy in winemaking. Considering the more rapid development of PV industry, PV chain and economic feasibility are analyzed. By taking China as an example, the comparison and asymmetry between PV production and active solar-related winemaking are stressed aimed at appealing to winemakers and policymakers to turn more to renewable energy like solar energy. Based on that, essential suggestions are provided, which are expected to extend solar energy systems for subsequent contributions to energy conversation, environmental protection and reduction of land occupation. [ABSTRACT FROM AUTHOR]

A balcony wall type solar water heater system was designed and constructed in a high-rise building. The U-type evacuated glass tube solar collector is fixed vertically on the balcony wall. The water, heated in the solar collector, flows through the exchanger coil in the water tank and then flows back to the solar collector. With regard to the hot water supply system, the cold water, heated by the heat exchanger, is sent to the point of use. Considering storeys and water consumption pattern, four apartments are selected for testing. Meanwhile, the theoretical analysis with TRNSYS was presented. According to the experimental results, mean daily collector efficiency is about 40%. Solar fraction is high in summer and autumn for the relative high radiation and high ambient temperature. Under given conditions, the annual energy extracted from tank is 2805.3 MJ/m 2 , and the annual solar fraction is 40.5%. When the tank volume-to-collector area ratio is decreased to 37.5 L/m 2 , the solar fraction can be increased to 50%. The results show that the family to use water all day round gets higher solar fraction than the family using hot water mostly in the morning and night. [ABSTRACT FROM AUTHOR]

CCHP (combined cooling, heating and power) system as a poly-generation technology has received an increasing attention in field of small scale power systems for applications ranging from residence to utilities. It will also play an important role in waste to energy application for megacities. However, how to evaluate and manage energy utilization of CCHP scientifically remains unclear. In this paper, energy level and exergy analysis are implemented on energy conversion processes to reveal the variation of energy amount and quality in the operation of CCHP system. Moreover, based on the energy level analysis, the methodology of energy matching and optimization for the CCHP system is proposed. By this method, the operational parameters of CCHP system can be deduced to obtain an efficient performance and proper energy utilization. It will be beneficial to understand and operate the CCHP system, and to provide a guiding principle of the energy conversion and management for the CCHP system. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a solar hybrid desiccant air conditioning system, which combines the technologies of two-stage desiccant cooling (TSDC) and air-source vapor compression air-conditioning (VAC) together, has been configured, experimentally investigated and theoretically analyzed. The system mainly includes a TSDC unit with design cooling capacity for 10kW, an air-source VAC unit with 20kW in nominal cooling capacity, a flat plate solar collector array for 90m2, a hot water storage tank and a cooling tower. Performance model of the system has been created in TRNSYS simulation studio. The objective of this paper is to report the test result of the solar hybrid air conditioning system and evaluate the energy saving potential, thereby providing useful data for practical application. Experimental results show that, under typical weather condition, the solar driven desiccant cooling unit can achieve an average cooling capacity of 10.9kW, which contributes 35.7% of the cooling capacity provided by the hybrid system. Corresponding average thermal COP is over 1.0, electric COP is up to 11.48. Under Beijing (temperate), Shanghai (humid) and Hong Kong (extreme humid) weather conditions, the solar TSDC unit can remove about 57%, 69% and 55% of the seasonal moisture load, thereby reducing electric power consumption by about 31%, 34% and 22%, respectively. These suggest that the solar hybrid system is feasible for a wide range of operating conditions. [Copyright &y& Elsevier]

Abstract: In this paper, a solar heating system, which combines the technologies of evacuated tube solar air collector and rotary desiccant humidification together, has been configured, tested and modeled. The system mainly includes 15m2 solar air collectors and a desiccant air-conditioning unit. Two operation modes are designed, namely, direct solar heating mode and solar heating with desiccant humidification mode. Performance model of the system has been created in TRNSYS. The objective of this paper is to check the applicability of solar heating and evaluate the feasibility and potential of desiccant humidification for improving indoor thermal comfort. Experimental results show that the solar heating system can convert about 50% of the received solar radiation for space heating on a sunny day in winter and increases indoor temperature by about 10°C. Compared with direct solar heating mode, solar heating with desiccant humidification can increase the fraction of the time within comfort region from about 10% to 20% for standalone solar heating and from about 30% to 60% for solar heating with auxiliary heater according to seasonal analysis. It is confirmed that solar heating with desiccant humidification is promising and worthwhile being applied to improving indoor thermal comfort in heating season. [Copyright &y& Elsevier]

Due to fossil fuel shortage and high carbon emissions, more and more inefficient coal-fired power plants are being decommissioned. Many redundant resources like chimneys and electric equipment are thus left behind, which can be combined with renewable energy for transformation. Therefore, a hybrid photovoltaic/solar chimney (PV/SC) power plant combined with agriculture is proposed to transform a decommissioned thermal power plant in Ningxia, China. The collector canopy is partially covered with PV modules and simultaneously serves as an agricultural greenhouse for planting activities. Meanwhile, the hot air flow under the canopy can be integrated with air source heat pumps (ASHPs) for domestic heating. Detailed mathematical models are developed to investigate power generation and heat collection performance. The economic and environmental benefits are quantitatively evaluated. The results show that the average daily power generation capacity of PV and SC can reach 334.2 MWh and 9.3 MWh, respectively. The total power generation capacity increases by 5.98% compared with an equivalent single PV power plant. The annual CO 2 emission reduction can be up to 1.27 × 106 tons, and the total annual revenue is more than $ 5.47 million. The transformed plant has an impressive comprehensive solar energy conversion efficiency of 14.2% considering power generation, agricultural production and heating, which is 36.9% higher than that of an equivalent conventional PV power plant. The proposed plant has a power generation capacity of 343.5 MWh/d and can bring about notable economic and environmental benefits, which are of great significance to the transition of renewable energy and achieving lower carbon emissions. This work can provide a feasible reference for the upgrading of industries with high pollution and low efficiency. [ABSTRACT FROM AUTHOR]

• Co-gasification of HW and SS was investigated using steam as gasification agent. • H 2 content was increased and syngas yield was decreased with higher SS ratio. • Syngas yield and H 2 production were significantly promoted by synergistic effect. • Optimal design and energy flow were performed for steam co-gasification. In this study, horticultural waste (HW) and sewage sludge (SS) with different mass ratios were co-gasified with steam at different temperatures to investigate the product distribution, gas synergistic interaction, and optimal design for gas products from co-gasification process. Results showed that with the increase of SS ratio in blends, the H 2 content was increased and the syngas yield was decreased. The synergistic interaction was more significant at higher temperature which promoted the H 2 production probably due to the reduction and steam oxidation of Fe species in SS during co-gasification process. The optimized highest effective gas content (82.92 vol%) was achieved with the highest HHV (11.40 MJ/m3) at the conditions of SS ratio = 0.80 and temperature of 900 °C. It indicates that steam co-gasification of HW and SS is a promising technology to produce desired syngas towards a clean and efficient waste management process. [ABSTRACT FROM AUTHOR]

Multi-energy system is currently under rapid development due to their potential to reduce the use of fossil fuel resources and improve system stability. A systematic simulation-based, multi-objective optimization model of for solar hybrid heat pump heating and cooling system is presented. A combined energy, economic and environmental analysis of the system is conducted to calculate the primary energy use as well as the levelized total annual cost. A multi-objective optimization model is formulated using a genetic algorithm to simultaneously minimize these objective. Linear programming technique for multidimensional analysis of preference (LINMAP) is used to select the optimal point from the Pareto front. A sensitivity analysis is also performed to assess the influence of fuel cost, capital cost of innovative components and the annual interest rate on the Pareto front of the optimal solution. • Systematic simulation and MOO model for solar hybrid heat pump system are presented. • Genetic algorithm is used for the model to minimize energy and economic objectives. • Sensitivity analysis of the influence of parameters on the Pareto front is made. [ABSTRACT FROM AUTHOR]

• The efficiency factor of direct expansion PVT module is derived and validated. • Proposed a novel design method for PVT module employing roll-bond evaporator. • Parameter analysis is conducted to evaluate the thermal performance of four different channel patterns. • Hexagon and rectangle types have better temperature uniformity while grid and linear types have lower pressure loss. Direct expansion solar assisted PVT (photovoltaic/thermal) heat pump is a combination of PVT technology and heat pump technology, which can improve the comprehensive conversion efficiency of solar energy, and it is suitable for solar heating applications. In this paper, the efficiency factor of direct expansion PVT module employing roll-bond panel has been theoretically derived, modified, and validated by experimental results. Moreover, the efficiency factor could be used to design, evaluate, and optimize the thermal performance of direct expansion solar assisted heat pump systems. In addition, parameter analysis of four evaporator unit types has been conducted, and the recommendation values of each parameter have also been presented. The simulation results show that the roll-bond evaporator (fluid channel width: 10 mm) with hexagon and rectangle patterns have better temperature distribution uniformity than grid and linear types, and their temperature differences are both 0.038 °C while their dimensionless pressure losses are 0.109 and 0.230, respectively. To specifically design different kinds of PVT collector/evaporator or direct expansion evaporators, a novel design method for roll-bond evaporator is proposed, and a combination of hexagon and grid types is recommended for PVT module. Moreover, the recommendation fluid channel width of the roll-bond panel is 8 mm to 13 mm while the scaling ratio is 0.8 to 1.2. The modified efficiency factors are 0.521, 0.564, 0.549, and 0.342 of hexagon, grid, rectangle, and linear types when the fluid channel width is 10 mm, respectively. [ABSTRACT FROM AUTHOR]

• Food waste acidogenic fermentation for volatile fatty acids production was studied. • The highest total VFAs yield was achieved at initial pH 7.0 at temperature of 35 °C. • Classes Clostridia , Bacteroidia and Bacilli dominated functional bacterial species. • Feasibility of continuous VFA production was validated using a leachate bed reactor. • Average total VFA concentration and yield were 6.3 g COD/L and 0.29 g VFA/g VS added. Acidogenic fermentation of food waste for production of volatile fatty acids (VFAs) contributes to both food waste minimization and resource recovery. To gain knowledge on functional bacterial communities and facilitate continuous production of VFAs, this research firstly studied the effects of initial pH values (i.e. 5, 6 and 7) and temperatures (i.e. 35 °C and 55 °C) on VFAs production, distribution, and bacterial communities during acidogenic fermentation of food waste. The optimal conditions were determined as pH 7 and 35 °C, corresponding to the highest total VFAs yield of 11.8 g COD/L with major components of acetic, propionic and butyric acid. Bioinformatic analysis showed that the relative abundance of the dominant bacterial classes (e.g. Clostridia , Bacteroidia and Bacilli) were changed by the initial pH values in both mesophilic and thermophilic reactors. NMDS analysis confirmed a significant difference between mesophilic and thermophilic communities. Finally, the feasibility of continuous production and recovery of VFAs was validated using a two-phase leachate bed bioreactor at the optimal conditions. Average concentration and yield of the total VFAs in the continuous operation were 6.3 g COD/L and 0.29 g VFA/g VS added , respectively. The findings in this study could provide pivotal technical supports for potential pilot- and commercial-scale biorefinery plants for VFAs production from food waste. [ABSTRACT FROM AUTHOR]

• A solar-driven GAX-based ammonia-water absorption heat pump was proposed. • Experimental and theoretical analysis on the system was carried out. • Thermal efficiency of the heat pump was optimized. • Effects of different operation parameters on system performance were analyzed. This research involves a GAX-based ammonia-water absorption heat pump, which utilizes solar energy and natural gas as heat source. The experiments of parabolic tough collector and GAX absorption heat pump were carried out separately. GAX absorption heat pump is operated when the ambient temperature is 4.31–11.07 °C, COP approaches 1.44–1.66. Thermal efficiency of the PTC varies from 0.50 to 0.60. A mathematical model of the coupled solar absorption heat pump is built. The effect of each heat exchanger size on the GAX cycle performance is investigated, results show that the heat exchanger size of solution cooled absorber has the greatest impact on the cycle. Both Solar driven mode and Solar-NG driven mode were studied. Solar driven mode is strict with solar energy, if the direct normal irradiance is below 560 W/m2 the system cannot work. Solar-NG driven mode could work under any solar radiation condition. In this mode, generation temperature could be controlled by changing the flow rate of natural gas. The optimal generation temperature is found to be around 180 °C when T amb = 7 °C, DNI = 800 W/m2, T wout = 45 °C. Besides, system analysis reveals that the heat pump could perform competitive in low ambient temperature if the solar radiation is abundant, which makes Lhasa a perfect site for the system. Economic analysis in Lhasa show that the addition of solar collector could reduce the operating cost by more than 25%. [ABSTRACT FROM AUTHOR]

• A solar PV/T heat pump is proposed for residential heating in high latitude area. • Design of build-in PCM heat storage unit is proposed and simulated. • The overall efficiency of this solar PV/T heat pump system can reach above 75%. PV/T (photovoltaic/thermal) technology is a combination of PV module (photovoltaic utilization) and collector (photothermal utilization), which can improve the comprehensive utilization efficiency of solar energy and has a broad application prospect. In this paper, PV/T module is coupled with heat pump evaporator to form a direct-expansion solar PV/T heat pump which is suitable for heat application in high latitude area. To achieve stable residential heating, a solar PV/T heat pump system coupled with build-in PCM (phase change material) heat storage is therefore proposed and simulated. Meanwhile, the mathematical model of solar PV/T heat pump coupled with build-in PCM heat storage system is established and verified. The simulation results show that the temperature of underfloor heating which using build-in PCM heat storage can reach 22–31 °C after 39 h when the circulating water is 40 °C. Moreover, the heating COP (Coefficient of Performance) increases with the increase of solar radiation, ambient temperature and area of PV/T collector, and decrease of wind speed, respectively. A 20 m2 PV/T panel module can output 21.4% of the electricity to power grid when the solar radiation intensity is 600 W/m2 and meet the heat demand of a 100 m2 room while maintain the operation of the system. Meanwhile, the heating COP can reach 5.79 which is 70% higher than the conventional air conditioning system and the electrical, thermal, overall efficiencies are 17.77%, 55.76% and 75.49%, respectively. [ABSTRACT FROM AUTHOR]

Removing benzene from indoor space plays an important role in indoor air purification. A novel filter with vegetal fiber paper (VFP) as matrix hosting silica gel is proposed in this paper for benzene removal. In order to investigate the feasibility and performance of this idea, firstly, three pieces of VFP samples impregnated with different amounts of silica gel are fabricated and their benzene adsorption quantities are tested. The results show that three times is recommended as the optimal number for impregnating. The VFP sample impregnated with silica gel after the third impregnating exhibits commendable coating stability and good benzene adsorption performance. Additionally, at low relative pressure (Pb/Ps ≤ 0.05), the experimental data of benzene adsorption isotherms fit well with the Langmuir model with R2 greater than 0.97. Then, two actual filters made of VFP impregnated with silica gel after the third impregnating were fabricated. It is found that the pressure drop of the actual filter is only 1200 Pa/m when the air velocity is 2 m/s. Besides, the one‐pass efficiency of the filter can reach to 19.44%. It is expected that the silica gel coated on the filter can be modified to improve the purification performance of the filter. [ABSTRACT FROM AUTHOR]

Abstract Ammonia-water absorption-resorption heat pump (ARHP) is a promising technology in efficient utilization of low-temperature heat for residential heating application. This paper proposes a balanced-type single-stage ARHP cycle based on the unbalanced ARHP cycle by eliminating the rectifier and depending on only one solution circulation pump. The proposed cycle can achieve internal mass and species conservation by changing the ammonia-water solution concentration difference at different pressure levels. A mathematical model is developed to obtain feasible high pressure/low pressure (P H / P L) pairs to enable the cycle. The cycle's coefficient of performance (COP) at different P H / P L pair values is investigated. The maximum COP is 1.51 and the corresponding heat supply temperature reaches 43.4 °C when P H / P L pair value is 1.50/0.48 MPa and heat source temperature is 95 °C. The maximum heat supply temperature can reach 53.4 °C and the minimum ambient air temperature to effect the cycle is − 5.8 °C. Other parameters like heat output/inputs, solution circulation ratios, and absorption and desorption concentration gradients in the absorbers and generators are studied. Inner pressure (difference), COP and heat source temperature demand have been compared with those of the conventional absorption heat pump (AHP) cycle and the unbalanced ARHP cycle. The results revealed that the proposed cycle could work at lower heat source temperature (above 82 °C) and within wider heat source temperature range than the conventional AHP cycle, indicating that the proposed cycle is potential in efficient utilization of commonly used solar collectors for space heating. In addition, the proposed cycle could be operated at higher COP values and lower inner pressure differences than the unbalanced ARHP cycle. Highlights • A balanced-type single-stage absorption-resorption heat pump cycle was studied. • Mathematical model was developed to explore feasible inner operation pressures. • COP values corresponding to different inner high/low pressure pairs were revealed. • Effects of different parameters on performance of the proposed cycle were analyzed. • Performance is compared with that of the AHP cycle and the unbalanced ARHP cycle. [ABSTRACT FROM AUTHOR]

Highlights • The energy and economic impacts of solar photovoltaic soiling were modelled. • Relative net-present value change was defined to assess optimal cleaning intervals. • We compared the soiling-induced efficiency and economic losses in seven cities. • The efficiency loss is the lowest (<0.04) for Tokyo and highest (>0.8) for Doha. • The optimal intervals are 23–70 days (manual) and 17–49 days (machine). Abstract This work developed a framework to predict the energy and economic impacts of solar photovoltaic soiling. This framework includes the effects of relative humidity, precipitation and tilt angle on solar photovoltaic soiling. A concept of relative net-present value change was introduced to determine the optimal cleaning interval. The uncertainties in the economic analysis were accounted for using a Monte Carlo simulation method. The framework was used to study the soiling-induced efficiency and economic losses of solar photovoltaic modules in seven cities (i.e. Taichung, Tokyo, Hami, Malibu, Sanlucar la Mayor, Doha, and Walkaway). Overall, the efficiency loss (in ascending order) for Tokyo/Walkaway < Taichung < Sanlucar la Mayor < Malibu/Hami < Doha for a one-year study period. Doha experiences an efficiency loss over 80% for a 140-day exposure, while Tokyo has an efficiency loss less than 4% for a one-year exposure. Malibu has longest optimal cleaning intervals (70 days for manual cleaning and 49 days for machine-assisted cleaning) that leads to the relative net-present value changes of 1.7% and 1.1%. Doha has the shortest optimal cleaning intervals (23 days for manual cleaning and 17 days for machine-assisted cleaning) that leads to the relative net-present value changes of 21% and 19%. The work serves as an effective tool for designing optimal cleaning protocols for solar photovoltaic systems. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) are promising for indoor humidity regulation due to steep stepwise water uptake and moderate regeneration temperature. Current approaches for performance improvement of MOFs such as impregnating hygroscopic salts and grafting functional groups face the challenge of corrosion and instability. Herein, a template‐guided tuning strategy is proposed to synthesize binary nanocomposite. Highly ordered mesoporous channels of MCM‐41 provide uniform nucleation sites for MOF growth, enabling a 21.5% promotion of specific surface area (3188.14 m2 g−1) and 23.4% improvement of water uptake (1.53 g g−1 at 20°C/90% relative humidity) for the nanocomposite compared with parent MIL‐101(Cr). The fast kinetics and superior stability together guarantee its practical application. Further, a paradigm of continuous indoor humidity regulation driven by sunlight is demonstrated, which realizes smart regulation of the indoor humidity to the human comfort zone (40–60%) with near‐zero energy input. [ABSTRACT FROM AUTHOR]

Particle number concentration, particle size distribution, and size-dependent chemical compositions were measured at a bus stop, alongside a high way, and at an industrial site in a tropical city. It was found that the industry case had 4.93 × 10 7 –7.23 × 10 7 and 3.44 × 10 4 –3.69 × 10 4 #/m 3 higher concentration of particles than the bus stop and highway cases in the range of 0.25–0.65 μm and 2.5–32 μm, respectively, while the highway case had 6.01 × 10 5 and 1.86 × 10 3 #/m 3 higher concentration of particles than the bus stop case in the range of 0.5–1.0 μm and 5.0–32 μm, respectively. Al, Fe, Na, and Zn were the most abundant particulate inorganic elements for the traffic-related cases, while Zn, Mn, Fe, and Pb were abundant for the industry case. Existing respiratory deposition models were employed to analyze particle and element deposition distributions in the human respiratory system with respect to some potential exposure scenarios related to bus stop, highway, and industry, respectively. It was shown that particles of 0–0.25 μm and 2.5–10.0 μm accounted for around 74%, 74%, and 70% of the particles penetrating into the lung region, respectively. The respiratory deposition rates of Cr and Ni were 170 and 220 ng/day, and 55 and 140 ng/day for the highway and industry scenarios, respectively. Health risk assessment was conducted following the US EPA supplemented guidance to estimate the risk of inhalation exposure to the selected elements (i.e. Cr, Mn, Ni, Pb, Se, and Zn) for the three scenarios. It was suggested that Cr poses a potential carcinogenic risk with the excess lifetime cancer risk (ELCR) of 2.1–98 × 10 − 5 for the scenarios. Mn poses a potential non-carcinogenic risk in the industry scenario with the hazard quotient (HQ) of 0.98. Both Ni and Mn may pose potential non-carcinogenic risk for people who are involved with all the three exposure scenarios. [ABSTRACT FROM AUTHOR]

• Combination of the absorption and vapor compression heat pump. • Maximum performance enhancements for heating is 45.8%. • Maximum performance enhancements for cooling is 18.9%. • Power savings for heating and cooling are 16.0% and 31.4%, respectively. • Lower the heat-driven temperature for absorption to 60 °C. Decarbonizing the energy sector becomes a key topic to solving man-made climate change. For achieving indoor thermal comfort conditions, conventional heating, ventilating, and air-conditioning systems consume so much energy in both residential and public buildings. In this paper, a novel solar-assisted absorption-compression system for both heating and cooling is proposed to utilize solar thermal energy throughout the year for the heating/cooling supply. The experimental prototype was built and operational modes including solar-assisted heating/cooling mode and vapor compression individual heating/cooling mode. The performance enhanced by assisted heat input of the proposed system is evaluated by comparing it with air-source heat pumps operated under the same ambient conditions. Performance indices consisting of COP ele increment, power-saving ratio (PSR) and energy-saving ratio (ESR) are presented. The results indicate that the combination of the absorption heat pump subsystem and the vapor compression subsystem lowers the heat-driven temperature to 60 °C and thus makes higher solar collection efficiency possible. The maximum of the COP ele increment and the PSR under solar-assisted heating mode are achieved at conditions with 80 °C hot water temperature, of 45.8% and 31.4%, respectively, and the corresponding value for solar-assisted cooling mode are 18.9% and 16.0%. The speed of compressor as well as fan frequency of terminal has a greater influence on heating performance that on cooling performance due to the different coupling mechanisms. [ABSTRACT FROM AUTHOR]

The performance of a solar-assisted DX-PVT heat pump (direct expansion photovoltaic-thermal) is intimately relevant to the system configuration. Inappropriate system configuration will undermine the system performance. This work assessed the effect of the equipment area of PVT modules on the PVT heat pump system driven by novel direct-expansion roll-bond PVT modules, and aimed to propose optimal system configuration. An analytical model was developed for the PVT heat pump system and validated by the experimental results. Simulations were conducted to reveal the effect of A / V t h , a proposed parameter to describe the system configuration, namely the ratio of the modules' area to the theoretical displacement of the compressor. The results showed that the larger A / V t h lead to higher COP but lower HGF (heat gain factor). With A / V t h increasing from 0.768 to 2.303 m2 h/m3, the COP increases by 61.3% (from 3.1 to 5.0) but the HGF decreases by 39.6% (from 0.91 to 0.55). Higher levels of solar irradiation strengthens the positive effect of the increasing A / V t h on thermodynamics performance and weakens the negative effect of that on the heat collection performance. The enhancement in COP is 42.8%/70.9% with A / V t h increasing from 0.768 to 2.303 m2 h/m3 when solar irradiation is 500 W/m2/800 W/m2, while the decrease in HGF is 49.2%/39.2%, respectively. A configuration optimization was also conducted to balance the thermodynamics and heat collection performance. The A / V t h varying from 1.535 to 1.919 m2 h/m3 was suggested as the optimized configuration when solar irradiation is 500 W/m2. After optimization, the IPLV and HGF can exceed that of air-source heat pump and flat-plate collectors by 40%, showing considerable performance advantages. [ABSTRACT FROM AUTHOR]

[Display omitted] • Machine learning applications for four critical biorefinery systems are analyzed. • Characteristics and limitations of common algorithms are summarized. • Advancements against modeling techniques of mechanistic approaches are studied. • Collective efforts for next-stage machine learning applications are highlighted. Biorefinery systems are playing pivotal roles in the technological support of resource efficiency for circular bioeconomy. Meanwhile, artificial intelligence presents great potential in handling scientific tasks of high-dimensional complexity. This review article scrutinizes the status of machine learning (ML) applications in four critical biorefinery systems (i.e. composting, fermentation, anaerobic digestion, and thermochemical conversions) as well as their advancements against traditional modeling techniques of mechanistic approach. The contents cover their algorithm selections, modeling challenges, and prospective improvements. Perspectives are sketched to further inform collective efforts on crucial aspects. The multidisciplinary interchange of modeling knowledge will enable a more progressive digital transformation of sustainability efforts in supporting sustainable development goals. [ABSTRACT FROM AUTHOR]

• Ionic liquid confined into mesoporous MCM-41 is prepared and characterized. • High sorption capacity of 0.5 g/g at 70 % RH and fast sorption kinetics are proved. • The composite sorbent has long-term cycling stability and is corrosion-free. • The dehumidification capacity is superior to traditional silica gel and MCM-41. Composite sorbents with hygroscopic salts (like LiCl and CaCl 2) impregnated porous matrixes obtained special attention in the past years, especially for solid desiccant dehumidification. However, the drawback of strong corrosivity limited their practical implementation. Alternatively, ionic liquid (1-ethyl-3-methylimidazole acetate) with less corrosivity is confined into ordered mesoporous MCM-41 to fabricate composite sorbent in this study, overcoming the poor mass transfer or limited adsorption capacity of single sorbent. Comprehensive characterizations including SEM, TEM, XRD, FTIR and N 2 adsorption prove that the ionic liquid is encapsulated in ordered channels of MCM-41. Sorption isotherms and kinetics indicate that the composite sorbent has superior water sorption performance (0.5 g/g at 20 °C/70 % RH), fast sorption rate under wide humidity range and potential of low temperature-driven regeneration. Moreover, the leakage test and corrosion experiment reveal that the composite sorbent has long-term stability and is corrosion-free to metal components. Further, the dehumidification performance using desiccant coated heat exchanger with reported composite sorbent is evaluated, showing 5 times higher dehumidification capacity than that of MCM-41 and 2 times higher than traditional silica gel (typical ARI summer, 35 °C, 40 % RH). This study identifies a feasible way of using ionic liquids to develop energy-efficient, safety-ensured and low-cost composite sorbents for water sorption-related applications. [ABSTRACT FROM AUTHOR]

The compositions of food wastes and their co-gasification producer gas were compared with the existing data of sewage sludge. Results showed that food wastes are more favorable than sewage sludge for co-gasification based on residue generation and energy output. Two decentralized gasification-based schemes were proposed to dispose of the sewage sludge and food wastes in Singapore. Monte Carlo simulation-based cost-benefit analysis was conducted to compare the proposed schemes with the existing incineration-based scheme. It was found that the gasification-based schemes are financially superior to the incineration-based scheme based on the data of net present value (NPV), benefit-cost ratio (BCR), and internal rate of return (IRR). Sensitivity analysis was conducted to suggest effective measures to improve the economics of the schemes. [ABSTRACT FROM AUTHOR]

• Quantifies hourly generation potential of building-integrated PV (BIPV) for Tokyo. • Shading effects and morphological characteristics of building stock are considered. • PV potential equivalent to 15%–48% of the annual energy demand in the year 2050. • Changes in hourly net electricity load and potential impacts are evaluated. The installation of photovoltaic (PV) modules is one of the most effective measures for decarbonizing urban building stock. The considerable potential of the process has been demonstrated using building-integrated PV (BIPV) modules. Earlier studies have provided significant knowledge about the PV potential of buildings, but a detailed investigation of the large-scale installation of BIPV modules on building façades has not been undertaken. In the present study, a model for estimating the hourly PV potential of building surfaces on a regional scale was developed and applied to commercial building stock in Tokyo, Japan. Analytical results showed that the generated PV power would be capable of satisfying 15%–48% of the annual electricity demand of the building stock in 2050, based on the extent to which the PV potential of building surfaces, especially façades, was exploited. This demonstrates the usefulness of BIPV for achieving a decarbonized society. Additionally, hourly estimation results showed that, if a higher economic efficiency is pursued, the use of large-scale installation of BIPV together with rooftop-mounted PV could increase the PV power generation without altering the hourly PV power fluctuation. However, electricity demand and generation analyses revealed the negative impacts of the larger-scale BIPV installation on the power system: The reduction in asset utilization and the increase in the need for flexibility. The findings of this study promise to be useful to policymakers in formulating guidelines for the use of BIPV modules. [ABSTRACT FROM AUTHOR]

• Adopting pre-digestion management of FW is vital for the advanced AD processes. • AI-guided FW collection and optimization scheme enables a resilient AD operation. • It is important to assess the microphysical properties of the FW to be valorized. • Real-time ADFW monitoring enables the prediction of potential methane output. • Deploying the FW AD plant on the existing waste treatment facility is suggested. With the continuous rise of food waste (FW) throughout the world, a research effort to reveal its potential for bioenergy production is surging. There is a lack of harmonized information and publications available that evaluate the state-of-advance for FW-derived methane production process, particularly from an engineering and sustainability point of view. Anaerobic digestion (AD) has shown remarkable efficiency in the bioconversion of FW to methane. This paper reviews the current research progress, gaps, and prospects in pre-AD, AD, and post-AD processes of FW-derived methane production. Briefly, the review highlights innovative FW collection and optimization routes such as AI that enable efficient FW valorization processes. As weather changes and the FW sources may affect the AD efficiency, it is important to assess the spatio-seasonal variations and microphysical properties of the FW to be valorized. In that case, developing weather-resistant bioreactors and cost-effective mechanisms to modify the raw substrate morphology is necessary. An AI-guided reactor could have high performance when the internal environment of the centralized operation is monitored in real-time and not susceptible to changes in FW variety. Monitoring solvent degradation and fugitive gases during biogas purification is a challenging task, especially for large-scale plants. Furthermore, this review links scientific evidence in the field with full-scale case studies from different countries. It also highlights the potential contribution of ADFW to carbon neutrality efforts. Regarding future research needs, in addition to the smart collection scheme, attention should be paid to the management and utilization of FW impurities, to ensure sustainable AD operations. [ABSTRACT FROM AUTHOR]

Freezing efficiency was the main factor affecting the efficiency of cold chain logistics and transportation. To further the ice storage performance, three mathematical models of the ice storage equipments were established to explore the influence of the number and the diameter of the tubes on the freezing time, heat flux, and natural convection by analyzing the distribution of the ice fraction and velocity. The results showed that the total freezing time of Type II and Type III, which were arranged the micro-tube, were 76.42 min and 137.50 min, which was more than 90% less than that of type I. Due to a ring cavity of water appearing near the shell of the ice storage tank increased the water natural convection, the freezing time required to increase the ice fraction by 0.05 gradually increased especially with the ice fraction greater than 0.95. To better evaluate the ice storage performance, the freezing efficiency was introduced. The freezing efficiency of Type II and Type III was lower than that of Type I by more than 2.24% and 2.14%, respectively, for the ice fraction range of 0.75 ~ 1. Given the freezing time and ice storage efficiency, it could be found that using type II and making the ice storage rate reach 0.95 could shorten the freezing time and improve the ice storage efficiency. [ABSTRACT FROM AUTHOR]

The low cost and efficient CaO catalysts have been successfully prepared from chicken manure by a simple calcination, in this present work. Chicken manure contains significant content of calcium compounds that can easily be converted into the active calcium oxide catalyst after calcination at 850 °C under air. The Hammett indicator test showed that the obtained CaO catalyst has the basic strength in a range of 15 < H_ < 18.4, revealing that the basicity of the obtained catalyst is mainly ascribed to the strong basic properties of metal–O groups. The obtained CaO catalyst exhibited high catalytic activity for biodiesel production from transesterification of waste cooking oil and methanol. Up to 90% FAME yield was obtained at optimum reaction condition (i.e. 7.5 wt% of catalyst, 15:1 of methanol:oil molar ratio and 65 °C). The experimental kinetic data fitted well with the pseudo-first order model and the activation energy was found to be 78.8 kJ mol −1 . Moreover, fuel properties of the produced biodiesel were determined according to the European standard and found to be within the specifications. The uses of chicken manure as a catalyst source and waste cooking oil as a raw material for biodiesel production not only offers the environmentally friendly and cost-effective way to recycle those wastes, but also help to lower the biodiesel production cost to make biodiesel competitive with petroleum-based diesel. [ABSTRACT FROM AUTHOR]

In this work, activated carbon (AC) as an effective and low-cost adsorbent was successfully prepared from carbon residue (or char, one of the by-products from woody biomass gasification) via physical activation. The surface area of char was significantly increased from 172.24 to 776.46 m 2 /g after steam activation at 900 °C. The obtained activated carbons were then employed for the adsorption of dye (Rhodamine B) and it was found that activated carbon obtained from steam activation exhibited the highest adsorption capability, which is mainly attributed to the higher surface area and the abundance of hydroxyl (–OH) and carboxyl (–COOH) groups on the activated carbon surface. Moreover, it was also found that the adsorption capability significantly increased under the basic condition, which can be attributed to the increased electrostatic interaction between the deprotonated (negatively charged) activated carbon and dye molecules. Furthermore, the equilibrium data were fitted into different adsorption isotherms and found to fit well with Langmuir model (indicating that dye molecules form monolayer coverage on activated carbon) with a maximum monolayer adsorption capability of 189.83 mg/g, whereas the adsorption kinetics followed the pseudo-second-order kinetics. [ABSTRACT FROM AUTHOR]

Widespread application of solar energy is severely restricted to its instability in time and space. Heat storage system is considered to be one of the most effective pathways to achieve long-term heat supply. Among all the heat storage technologies, solution concentration difference storage technologies stand out for low heat loss and high energy density. By substituting condenser and evaporator in conventional absorption cycle with a high-pressure absorber and low-pressure generator, a resorption cycle could be established. Compared with absorption heat storage cycle, working pressure of resorption heat cycle is lower, making it possible to utilize low-pressure heat source. Two-stage heat source cycle is further proposed to lower working pressure and upgrading supply water temperature. Resorption energy storage cycle with solution concentration difference is established and studied. A prototype based on two-stage ammonia-water resorption heat storage cycle was set up and tested. The result shows that the constraint relation between ambient temperature and heat source temperature of the proposed system. In single-stage mode, the lowest working ambient temperature is 5 °C when heat source temperature is 90 °C. The lowest working ambient temperature could be declined to 0 °C when heat source temperature rises to 120 °C. In two-stage mode, the lowest working ambient temperature is 0 °C when heat source temperature is only 110 °C, which proves the adaptability of two-stage cycle. The highest ESCOP appears in the 15 °C–120 °C single-stage mode, which is 0.742. The highest COP is 1.324 under the same condition. The highest energy density occurs in two-stage mode, which is 467.07 kJ/kg when ambient and heat source is set as 15 °C, 120 °C. The advantage that two-stage mode could enlarge solution concentration difference is verified. • A novel two-stage resorption energy storage system was proposed. • A prototype based on two-stage resorption energy storage system was established. • The heat performance and energy storage density of resorption energy storage system was studied. • The working domains of resorption energy storage system was investigated. [ABSTRACT FROM AUTHOR]

Absorption-resorption heat pumps (ARHPs) have great potential in utilizing low-temperature solar heat for efficient winter heating, but are limited by their weak adaptability to cold climates relative to absorption heat pumps (AHPs) and vapor compression heat pumps (VCHPs). In this work, a resorption-compression cascade system consisting of ARHP and VCHP subsystems is proposed and investigated, with the goal of achieving efficient winter heating with improved solar contribution in cold climates. Thermodynamic models of the two subsystems and of the whole cascade system are developed for system feasibility verification and performance evaluations. Feasible operation temperature and pressure conditions are identified in terms of internal subsystem matching. Based on these operation conditions, the primary energy ratio (PER) – which is a key performance evaluation index – is investigated over a range of solar fractions (f). The results show that for cases without solar contribution, the PER can be generally >0.95 under feasible operating conditions. In addition, the primary energy saving ratio (PESR) and heating capacity lift ratio (ε lift), as well as the heat source temperature (T h) and ambient temperature (T amb) restriction, are all investigated and compared to those of other, competing heating systems. The results show that the proposed system can reduce the T h demand to 69 °C (with a minimum T amb of −21 °C) and extend the operational T amb to −31 °C (with a minimum T h of 90 °C), while importantly achieving PESR > 0.20 and ε lift > 20 % under the above extreme conditions. Moreover, when integrating the system with solar heat with f > 43 %, the proposed solar-assisted system has a clear PER advantage over an equivalent VCHP system in the T amb range from −31 °C to 10 °C, highlighting the possibility of achieving higher solar contribution in cold climates. • A novel resorption-compression cascade heat pump system was proposed. • Performances were compared with those of the VCHP and subcooling coupled system. • Potential of high solar contribution to heating in cold climates was stressed. • The system could be operated in ambient above −31 °C with heat source over 90 °C. • The system with solar fraction over 43 % has advantage over the equivalent system. [ABSTRACT FROM AUTHOR]

• Solar photovoltaic-assisted ground-source heat pumps are studied in Nordic climate. • Ground regeneration with solar thermal energy improves long-term performance. • Designs are compared in terms of energy efficiency, cost, and ground heat transfer. • Photovoltaic-thermal leads to lower investment costs by reducing the borehole size. Ground source heat pumps (GSHP), as a renewable energy technology, are highly efficient systems suitable for meeting the heating needs of buildings, particularly in heating-dominated regions like Scandinavia. This study aims to better define the scope of application and sizing of GSHP combined with photovoltaic-thermal (PVT) collectors in Nordic conditions. The study compares seasonal performance factors (SPF), average ground temperatures, and investment costs for heating different numbers of apartment blocks in two distinct Nordic climates: Baltic climate and cold continental climate. To assess the long-term effects on the energy performance of GSHP + PVT systems, dynamic simulations using the TRNSYS software are conducted over a period of 50 years. The results demonstrate that PVT improves the long-term system performance, particularly in large and compact borehole (BH) fields, while in smaller BH fields, natural regeneration keeps playing a substantial role. For instance, PVT added to a GSHP system with large BH field can limit the ground temperature reduction after 50 years by 33 % compared to the configurations without PVT. In contrast, this reduction is only 13 % for systems with small BH fields. Moreover, the results show that GSHP + PVT can lead to a reduction of up to 95 % in the required area for installing the BH field while maintaining (almost) the same energy performance compared to a conventional GSHP. Notably, this study shows that the utilization of GSHP + PVT leads to a substantial reduction in BH length (up to 50 %) while maintaining a similar system SPF. It leads to a decrease in investment costs of up to 9.32 % and 22.92 % for the scenarios located in Norway and Sweden, respectively, compared to the case with PV instead of PVT. These findings suggest that PVT integration holds promise for advancing the GSHP adoption in high-latitude regions, especially in larger installations and colder climates, by mitigating investment costs while preserving the system SPF and ground temperature stability. [ABSTRACT FROM AUTHOR]

To clarify the importance degree and assess the effect of key parameters on comprehensive performance during operational adjustment, the artificial neural network (ANN) method is employed to quantitatively analyze the supercritical CO 2 (sCO 2) cycle performance for the advantage of accurate prediction and regression capabilities. The effects of seven operating parameters on the performance of the simple sCO 2 cycle, recompression sCO 2 cycle, and partial cooling sCO 2 cycle are discussed. The test results obtained through the ANN method depict that the key parameters are turbine inlet temperature (T TIT) and pressure ratio (P r) according to importance degree ranking. The maximum relative errors observed in the quantitative analysis of thermal efficiency and input heat are 2.48% and 3.47%, respectively. Additionally, the performance comparison of the quantitative analysis shows that the R2 values of thermal efficiency, output work, and input heat in this research are 0.057025, 0.0001381, and 0.019063 higher than those in the MATLAB software. Furthermore, the recommended operating parameters for T TIT and P r are 500/900/500 °C and 2.266/3.378/2.276 in the three sCO 2 cycles to achieve multi-objective optimization. The corresponding values for thermal efficiency, output work, and input heat are 44.91%/57.7%/44.05%, 104.8761/278.3495/109.5893 kJ/kg, and 190.3585/198.9562/198.8478 kJ/kg, respectively. This research can contribute to expanding future investigations on adjusting experimental parameters to enhance the performance of sCO 2 cycles. [Display omitted] • The ANN method is employed to quantitatively analyze the sCO 2 cycle performance. • The key parameters for sCO 2 cycles are turbine inlet temperature and pressure ratio. • The R2 values of η th , w tur , and q in are larger than 0.986 in the simple sCO 2 cycle. • The recommended values for T TIT and P r are 500/900/500 °C and 2.266/3.378/2.276. [ABSTRACT FROM AUTHOR]

An epitrochoidal rotary reactor for solar hydrogen production via a water-splitting thermochemical cycle using nonstoichiometric ceria is proposed. The reactor performs solid-phase heat recovery in the form of mechanical energy via isentropic compression and expansion of the sweep gas. A thermodynamic analysis for a system consisting of the epitrochoidal rotary reactor and two exchangers is presented. Under typical conditions with a solar concentration ratio of 3000, reduction temperature of 1773 K , oxidation temperature of 1073 K , gas-phase heat recovery effectiveness of 0.9, mechanical energy recovery effectiveness of 0.85, and the ratio of the molar flow rates of sweep gas and ceria of 10, the solar-to-fuel efficiency is 13.2%. The thermodynamic analysis demonstrates the potential of using an epitrochoidal rotary reactor for convenient solid-phase heat recovery without sacrificing the solar-to-fuel efficiency. • A conceptual epitrochoidal rotary reactor is proposed for solar hydrogen production. • The reactor can perform convenient heat recovery in the form of mechanical energy. • A thermodynamic model is developed for pressurized solar thermochemical reactors. • A solar-to-fuel efficiency of 13.2% is predicted. [ABSTRACT FROM AUTHOR]

In this study, a distributed aerobic composting system was proposed and simulated assisted by a solar photovoltaic thermal (PV/T) heat pump. The PV/T heat pump was adopted to provide the electrical energy and heat energy required by the aerobic composting system. In addition, the area of solar photovoltaic panels required for compost fermenter at different volumes was calculated, and the effects of ambient temperatures, wind speeds and solar radiation intensities on the performance exhibited by the hybrid system were investigated. As indicated from the result, when the temperature of the composting tank was maintained at 60 °C, the C/N ratio can be reduced to 11.5:1 and the GI can reach 101.7%, satisfied the compost maturity standard. Moreover, as the ambient temperature decreased, the heat loss of the composting system and the energy consumption of the hybrid system increased. The wind speed did not significantly impact the comprehensive performance exhibited by the system. Under the average solar radiation of 600 W/m2, a maximum of 10 m2 PV/T panels could be installed on the top of a standard container, and a maximum of 6000L of aerobic composting system could be installed within the container. Accordingly, the 6000L composting system coupling with PV/T heat pump could generate 85.64 kWh electricity in one period (10 days) without consuming energy. [ABSTRACT FROM AUTHOR]

A performance comparison of experimental results for CO2trans-critical cycle is presented for an overview of the current level of technology. The published performance data were collected as research objects through comprehensive literature review on experimental research. The methods for data processing, error analysis, and performance evaluation are introduced in the research methodology section. Through the proposed research method, 28 groups of performance results from developed prototypes or test rigs are compared and analyzed using the coefficient of performance and the second law efficiency of thermodynamics. A discussion of the performance comparison between developed CO2devices and commercial products of synthetic working fluid is also presented based on China's national standards (General Administration of Quality Supervision, Insection and Quarantine of the People's Republic of China 2001, 2003). Based on the comparison results, the state-of-art and possible research directions for CO2trans-critical cycle technology are summarized and presented. [ABSTRACT FROM AUTHOR]

[Display omitted] • Theoretical and run-test evaluation of the 50 MW beam-down power plant is conducted. • The variation in heliostat efficiency, flux density, and power generation is analyzed. • The average outlet temperature of the molten salt was up to 559℃ for 50 min. • The flux density of hyperboloid mirror on four typical days is 10.2/11.2/10.9/9 kW/m2. • The flux density of receiver on four typical days is 353.6/399.1/381.7/314.2 kW/m2. The beam-down concentrating solar power plant has the advantages of high concentrating ratio, low installation and maintenance requirements, and low pump consumption. To conduct further theoretical and run-test evaluations of the optical and thermal performance of the beam-down concentrating solar power system, the Yumen Xinneng 50 MW beam-down power plant is analyzed in this research. The variation of the heliostat field efficiency, hyperboloid mirror flux density, receiver flux density, and annual power generation under various operating parameters is discussed. The run-test results from June 12th indicated an average outlet temperature of molten salt reached 559°C between 13:07 and 13:56 under an average direct normal irradiation of 739.7 W/m2. The corresponding inlet temperature increased from 302.3°C to 307.6°C due to the rewarming effect caused by the increase in hot molten salt. Regarding the simulation results, the recommended design parameters for the vertex ratio of the hyperboloid mirror are between 0.775 and 0.8 to mitigate the contradiction between initial investment and optical efficiency. The maximum values of cosine efficiency, shading and blocking efficiency, shading efficiency of the hyperboloid mirror, and attenuation efficiency for the heliostat field are 85.56%, 99.96%, 99.35%, and 97.46% on June 1st for the maximum solar elevation angle of 70.72°. Consequently, the maximum values of the average hyperboloid mirror flux density and receiver flux density are 11.2 kW/m2 and 399.1 kW/m2 on June 1st. The maximum power generation for a 7-day period is 4674.22 MWe in June with a duration time of 100 hours. This paper can further expand research on the comprehensive performance of beam-down power plants. [ABSTRACT FROM AUTHOR]

A novel solar assisted heat pump (SAHP) system for in-bin grain drying was proposed to solve the problems of poor uniformity and long drying time of grain in depot with higher initial water content in high grain piles. The effects of different operational parameters on the drying performance were numerically and experimentally investigated. The experimental results indicated that the thermal efficiency of the solar collector and the COP of the heat pump reached 63% and 5.03 under given conditions. The average heating capacity of the SAHP system was 130.2 kW, consistent with the simulation results under a typical sunny day in winter. The average water content of 3,760 tons of grain dropped from 12.9% to 12.5% after 42 h of drying. The specific moisture extraction rate of the proposed system and the exergy efficiency of the grain bin were 1.934 kg/kWh and 40.27%, respectively. The operating cost of SAHP grain drying decreased from 5.57 $/t to 1.43 $/t compared with the grain drying machine for the same drying weight. The daily drying capacity increased from 166 t/d to 334 t/d compared with the mechanical ventilation drying for the same water content reduction rate. This investigation provided guidance for expanding future researches on the SAHP system applied for in-bin grain drying. • A novel in-bin grain drying system using solar collectors coupled with air source heat pump is proposed. • The drying performance of the proposed system is numerically and experimentally investigated. • The average moisture content of 3,760 tons of corn dropped from 12.94% to 12.5% after 42 h of drying. • The specific moisture extraction rate of the SAHP grain drying system was 1.934 kg/kWh. • The payback period of the SAHP grain drying system was 0.33 years. [ABSTRACT FROM AUTHOR]

Abstract: Thermodynamic analyses of desiccant cooling cycle usually focus on the overall cycle performance in previous study. In this paper, the effects of the individual irreversible processes in each component on thermodynamic performance are analyzed in detail. The objective of this paper is to reveal the elemental features of the individual components, and to show their effects on the thermodynamic performance of the whole cycle in a fundamental way. Appropriate indexes for thermodynamic evaluation are derived based on the first and second law analyses. A generalized model independent of the connection of components is developed. The results indicate that as the effectiveness of the desiccant wheel increases, the cycle performance is increased principally due to the significant reduction in exergy carried out by exhaust air. The corresponding exergy destruction coefficient of the cycle with moderate performance desiccant wheel is decreased greatly to 3.9%, which is more than 50% lower than that of the cycle with low performance desiccant wheel. The effect of the heat source is similar. As the temperature of the heat source increases from 60°C to 90°C, the percentage of exergy destruction raised by exhaust air increases sharply from 5.3% to 21.8%. High heat exchanger effectiveness improves the cycle performance mainly by lowering the irreversibility of the heat exchanger, using less regeneration heat and pre-cooling the process air effectively. [Copyright &y& Elsevier]

Abstract: A solar-powered adsorption chiller with heat and mass recovery cycle was designed and constructed. It consists of a solar water heating unit, a silica gel-water adsorption chiller, a cooling tower and a fan coil unit. The adsorption chiller includes two identical adsorption units and a second stage evaporator with methanol working fluid. The effects of operation parameter on system performance were tested successfully. Test results indicated that the COP (coefficient of performance) and cooling power of the solar-powered adsorption chiller could be improved greatly by optimizing the key operation parameters, such as solar hot water temperature, heating/cooling time, mass recovery time, and chilled water temperature. Under the climatic conditions of daily solar radiation being about 16–21MJ/m2, this solar-powered adsorption chiller can produce a cooling capacity about 66–90W per m2 collector area, its daily solar cooling COP is about 0.1–0.13. [Copyright &y& Elsevier]

This study focused on conversion of algal biomass to bio-oil through in-situ catalytic fast pyrolysis. In particular, novel Ni 2 P-loaded and unmodified (zeolite, activated carbon and chicken manure biochar) catalysts were evaluated to determine their effect on in-situ upgrading of algal pyrolysis products. Among the catalysts evaluated, Ni 2 P-loaded zeolite achieved the highest bio-oil hydrocarbon (34.97 %) and calorific value (32.66 MJ/kg), and the lowest O/C (0.075) and N/C (0.074) ratios. There was a 137 % increase of the aliphatic hydrocarbon fraction and a 72 % increase of the biochar specific surface area (SSA) with the loading of Ni 2 P to zeolite. Additionally, unfavourable major oxygen- and nitrogen-containing compound, phytol and tetradecanamide, decreased seven- and six-fold, respectively, compared to the non-catalytic baseline case. Ni 2 P-loaded biochar achieved a reduction in the bio-oil acidity from a pH of 4.52–6.78 and a 41 % decrease of the carboxylic acids content. Biochar produced from the zeolite formulations exhibited especially favourable sorbent quality with SSA greater than 500 m2/g. According to the proposed catalytic mechanism, the generation of n-heptadecane and hexadecanamide may be due to the decomposition of phytol and tetradecanamide, and the catalytic activity was correlated to the pore size of the catalyst (22.22 Å). Direct addition reactions were the dominant pathway in the formation of liquid hydrocarbons. These results suggest that it is feasible to develop an in-situ multi-catalyst system to achieve high-quality bio-oil production. Thus, the development of novel Ni 2 P-loaded catalysts addressed a promising approach for biomass conversion into hydrocarbon-rich products with low risk to the environment. [Display omitted] • Novel Ni 2 P-loaded catalysts were effective at reduction of heteroatom species. • Ni 2 P-loaded chicken manure biochar catalyst was effective at neutralizing high acidity in algal bio-oil. • Ni 2 P-loaded zeolite catalyst achieved the highest hydrocarbon and lowest oxygenous and nitrogenous species concentrations. • Ni 2 P-loaded catalysts achieved biochar specific surface areas greater than 500 m2/g. • A catalytic mechanism and formation pathways of bio-oil aromatic and aliphatic hydrocarbons are proposed. [ABSTRACT FROM AUTHOR]

• Pretreated OPEFB was anaerobically digested at mesophilic conditions. • Clarified manure was added into the digestion process resulting in 49% higher methane production. • Pretreatment increased methane yield by 19.7 – 52.7% over control. • Pretreatment allowed 94.9% of cellulose and 99.6% of hemicellulose to be converted. Food and energy requirements are increasing globally, and the challenge is to meet these demands in a sustainable manner. Oil palm has a relatively high productivity, but produces the lignocellulosic residue of empty fruit bunches (OPEFB). In this study, wet oxidation pretreatment is utilized to overcome the recalcitrance of OPEFB during semi-continuous anaerobic digestion (AD) with between 19.7 and 52.7% improvement over the control, and near total cellulose and hemicellulose content could be degraded. Clarified manure, the water phase of cattle and dairy manure after filtration, is further tested for its effect on methane production by providing necessary micronutrients and vitamins. An increase of 49% was found after addition of clarified manure to OPEFB compared to without this addition. [ABSTRACT FROM AUTHOR]

[Display omitted] • An ETSC with inner concentrating by reflective coating was proposed and fabricated. • The best coating angle was 180° and efficiency increased with eccentric distance. • The thermal efficiency of the novel inner concentrating ETSC was increased by 10%. • The heat loss coefficient of the ETSC-IC was decreased by 27% to 48%. Evacuated tube solar collector (ETSC) is widely used for domestic and industrial applications. Using reflective coating in an ETSC to realize concentration is a method to heighten the thermal efficiency due to solar irradiation could be reflected by the coating on the lower half of the outer glass tube and concentrated to the eccentric inner absorber. In this paper, an evacuated tube solar collector with inner concentrating (ETSC-IC) by reflective coating was proposed and fabricated. A series of experimental tests of the ETSC-IC was conducted to investigate the thermal performance. In addition, the mathematical model of the novel collector with inner concentrating was developed, and the structural parameters of the inner reflective concentrating evacuated tube, including the coating angel and the eccentric distance, have been analyzed. The optical and thermal analysis revealed that the best coating angle of the evacuated tube was 180°, and the thermal performance of the ETSC-IC enhanced with the increase of the eccentric distance under the best coating angle. The thermal efficiency of the ETSC-IC could reach 0.65 to 0.72 on the condition that the solar irradiation was around 950 W/m2 and the temperature of inlet water varied between 45 °C and 70 °C, and the ambient temperature was 31.2 °C. The thermal efficiency of the ETSC-IC was improved by approximately 10% compared with the conventional evacuated tube due to the enhanced irradiation concentrating and the reduction of heat loss caused by the coating on the outer glass tube. [ABSTRACT FROM AUTHOR]

• A medium-temperature selective coating obtained by co-sputtering titanium and aluminum targets was studied. • A novel CPC evacuated tube solar collector using the selective coating was developed. The instantaneous efficiency based the gross solar collector area is significantly higher than that of ordinary collectors. • An experimental steam system was built to verify the practical performance of the collector, it shows that after several years of operation, the collector still has excellent performance. This paper describes the development of a novel CPC (compound parabolic collector) evacuated tube solar collector, using a medium-temperature selective coating. The medium-temperature selective coating was obtained by co-sputtering titanium and aluminum targets. The absorptance and the thermal emittance of the heat treated coating is 0.95, and 0.04 at 80℃ respectively. The collector was optimized, using a manifold of copper U-tube with anti-oxidized coating and aluminum fin. An anti-reflection layer is added on the cover glass tube, and non-flash getter are used for maintaining the vacuum of the collector tubes. Thermal test results shown that the instantaneous efficiency based on gross area η G can reach 0.46 at the temperature of 150℃ and the normalized temperature difference T m * is 0.13 [(m2-°C)/W]. The experimental steam system application showed that the novel CPC solar collector can produce steam from water with temperatures about 108–145 °C during sunny days. It was also shown that the thermal performance of the solar collector did not degraded significantly. [ABSTRACT FROM AUTHOR]

The photovoltaic-thermal heat pump system, which integrates multiple energy technologies, can meet the building's diverse energy needs. This study evaluates the energy, economic, and environmental performance of a direct-expansion photovoltaic-thermal heat pump system for domestic hot water supply through a life cycle approach. The annual thermal and electrical outputs are estimated. On this basis, economic analysis is conducted with indicators of life cycle cost, levelized cost of heat, and investment payback time. Moreover, a detailed life cycle assessment is performed to evaluate the environmental impact, following three methods: cumulative energy demand, IPCC 2021 global warming potential, and ReCiPe 2016 Endpoint. Results show that the proposed system is highly effective, with a 9.67% increase in annual electricity output over traditional photovoltaic systems and a self-sufficient rate of 88.21%. The system also has a significantly lower environmental impact than conventional heating systems, with a life cycle environmental impact of only 3–5% compared to electric boilers. The environmental payback time ranges from 0.33 to 5.18 years, according to the three methods used in the study, which is shorter than the investment payback time of 2.49–5.21 years, suggesting the need for cost reduction for future promotion. Moreover, electricity consumption during the operation stage accounts for 32–52% of the total environmental impacts. Thus, decarbonization of the power grid and improvements in system efficiency can significantly reduce the system's environmental footprint. Overall, the photovoltaic-thermal heat pump system is an intriguing strategy for building energy conservation, offering high energy efficiency, acceptable costs, and low environmental impact. • A direct-expansion photovoltaic-thermal heat pump system for hot water production. • Operation simulation, life cycle cost, and life cycle assessment are conducted. • Investment, energy, CO 2 , and total environment payback time are evaluated. • The main factors impacting environmental performance are identified. • The system outperforms conventional systems in energy and environmental aspects. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel solar-driven biomass chemical looping gasification system is studied. • The system achieves a carbon-gas yield of 0.69 and an energy upgrade factor of 0.71. • The fuel reactor produced CH 4 , CO, CO 2 and H 2 at 0.63, 11.86, 8.85, and 18.53 mmol/g. • High-purity H 2 is produced at 7.17 mmol/g in a separated stream. • Fayalite is found as a byproduct due to the interaction between reactants. A novel solar-driven biomass chemical looping gasification (SBCLG) system was proposed and experimentally demonstrated for the co-production of pure hydrogen and syngas from biomass wastes using high-flux solar irradiation. In this system, a steam reactor and a solar fuel reactor were adopted to replace the air and fuel reactors in a typical biomass chemical looping gasification (BCLG) system, respectively. The SBCLG exhibits two advantages over BCLG: (1) the syngas yield is raised as the high-temperature process heat is provided by solar radiation rather than biomass combustion, and (2) a pure hydrogen stream is generated in addition to the syngas stream, which allows a flexible adjustment of the carbon-to-hydrogen ratio for downstream chemical processes. This study marked the first demonstration of a complete cycle of SBCLG in a cavity-type packed-bed solar reactor under simulated high-flux solar irradiation. Magnetite (Fe 3 O 4) was circulated between the steam reactor and the solar fuel reactor as the oxygen carrier (OC). The optimal operational parameters, the reaction temperature and solid contact pattern, were first determined in preliminary experiments in an electric furnace. Then, the effect of biomass to oxygen carrier mass ratio (m RH : m OC) on the key performance indicators was also investigated in a solar reactor. When m RH : m OC = 1:2, the highest values of the average carbon-gas yield of 0.69 ± 0.05 and energy upgrade factor of 0.71 ± 0.04 were achieved. The solar fuel reactor produced CH 4 , CO, CO 2 and H 2 at 0.63, 11.86, 8.85, and 18.53 mmol/g biomass, respectively, with the steam reactor yielding high-purity H 2 at 7.17 mmol/g biomass. The results indicated that the SBCLG is a viable method for co-production of pure hydrogen and syngas in separate streams. [ABSTRACT FROM AUTHOR]

• Experimental investigations of pyrolysis and decomposition of polypropylene plastic. • Effect of temperature (600 ~ 800 °C) and catalyst on properties of carbon product. • Temperatures higher than 700 °C was required to grow high quality CNTs. • CNTs with 20 ~ 30 nm diameters and high graphitization obtained by FeNi1 catalyst. Thermal chemical processing of plastic has been seen as an efficient practice for the disposal and resource utilization facing the current plastic waste problem. A pyrolysis followed by catalytic decomposition process was investigated in this work to produce carbon materials from polypropylene plastic over FeNi catalysts. The effects of both catalysis temperature (600, 700 and 800 °C) and catalyst type on the gaseous yields, as well as the physicochemical properties (morphology, porosity, purity and graphitization degree) of the as-obtained carbon materials were systematically explored. Various technologies including high resolution electron microscopies, temperature programmed oxidation, Raman, X-ray diffraction were used for full characterizations of the as-obtained carbons. Results show that the yields of both carbon and hydrogen gas were significantly proportional to the catalysis temperature. In terms of the physiochemical properties of carbon materials, the low catalysis temperature of 600 °C generated the majority amorphous and disordered carbons, due to the insufficient decomposition reactions and low catalyst activity. Catalysis temperature higher than 700 °C was necessary for the successful growth of carbon nanotubes, while further increase in temperature mainly acted on the yield rather than thermal stability and graphitic degree. High purity multi-walled carbon nanotubes with outer diameters of 20–30 nm and length up to few micrometers were generated with FeNi1 at 800 °C. FeNi1 catalyst synthesized by sol–gel method displayed higher activity towards the production of high quality carbon materials than FeNi2 catalyst at any temperature range investigated, due to the porous structure and the uniform dispersion of metal particles. [ABSTRACT FROM AUTHOR]