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The integration of the active heat storage system utilizing multiple heat storage and release media for prefabricated solar greenhouses with flexible material wall (PGFMW) can solve the problem of "good thermal insulation and weak heat storage" in PGFMW. However, it is still unclear on the heat storage and exothermic properties of the multiple media in the combined heat storage system. This study aims to perform on a PGFMW that equipped with a combined "air source ground heat exchange-back wall water circulation (AGHE-WWC)" heat storage system. A systematic investigation was also made on the individual and combined heat storage and release properties. A series of experimental tests were conducted to calculate the energy transfer. The results indicated that the minimum temperature of indoor air at night time was maintained above 10℃, and the maximum difference in temperature between indoors and outdoors was 26.5 °C in winter. The primary heat storage medium was identified as the 0-50 cm soil layer of the cultivation area in the PGFMW. Furthermore, the heat storage capacity of the soil layer reached 706.30 MJ on sunny days, accounting for 63.5% of the total heat storage. The difference in temperature between the inlet and outlet of the underground heat exchange was up to 10.8 °C, which increased by 54.4% in the heat storage capacity of the soil layer. The water circulation was used to store the heat energy of 424.04 MJ on the day, which accounted for up to 45.1% of the total heat storage. Specifically, after cloudy days, the temperature of 8 m3 of water in the storage tank increased from 11 to 35℃ by water circulation over two sunny days. In order to evaluate the rate of heat storage and release for the system in combination and individually, an evaluation index called the heat storage and release efficiency ratio (HRE) was inducted to assess system performance. It was found that the maximum absolute value of the HRE for water circulation system was 1.62, which was 1.8 times than the soil HRE on the same day. It proved that the water circulation system releases heat more rapidly compared to the soil on cloudy days. In terms of the total heat, the soil was remained the primary source of indoor heat release on the consecutive cloudy days. In addition, the "AGHE-WWC" heat storage system was realized to sustain the heat demand for a total of three consecutive cloudy days. Meanwhile, the average heating coefficient of performance (COP) and the uderground heat exchange COP were 9.16 and 6.82, respectively. The combined COP of the "AGHE-WWC" heat storage system was 8.85, while the energy saving rate was as high as 60.26%, compared with the heat pump. The finding can provide a strong reference for heat storage and release in combined heat storage systems. [ABSTRACT FROM AUTHOR]

The study aims at investigating the impact of ultrasound enhancement on the water change and quality characteristics of dried carrots by heat pump drying (HPD). The results showed that ultrasound had obvious strengthening effect on the drying and dehydration process of HPD, but there was an attenuation effect of ultrasound in the propagation process of materials, and the magnetic resonance imaging results could visually demonstrate the change and migration of moisture inside carrot slices. Higher drying temperature and ultrasonic power could cause more micropores and higher content of polyphenols, flavonoids and niacin of carrot slices. Conversely, the elevated drying temperature reduced rehydration ratio. β-carotene content showed a trend of increasing first and then decreasing due to excessive temperature and ultrasonic power. Based on AHP-CRTITC method, the highest comprehensive score was attained at drying temperature of 60 °C and ultrasonic power of 80 W. Therefore, the reinforcement effect of ultrasound on HPD process could significantly enhance dehydration rate and improve product quality. [ABSTRACT FROM AUTHOR]

This research investigates a polyvalent heat pump that simultaneously produces hot and cold water and uses natural refrigerants. The novelty of using a 48 V direct current compressor driven by solar photovoltaic (PV) energy and the staged retrofitting improvements to this heat pump are discussed. Empirical testing has indicated that using a suction line heat exchanger yields a 30% improvement in the heating Coefficient of Performance (COP). Rising ambient temperatures could positively and negatively impact its heating and cooling performance, respectively. In addition, an average COP of 3.8 was obtained after a one-hour simultaneous mode operation, with the average hot tank temperature rising from 32.7 to 58.9°C and the average cold tank temperature dropping from 18 to 14.4°C. Being capable of operating the polyvalent heat pump under renewable energy sources and utilizing all its generated heating and cooling energy contributes further to the electrification and decarbonization of residential buildings. [ABSTRACT FROM AUTHOR]

This paper discusses the performance of cold storage using R32 refrigerant. R32 is one of the recommended refrigerants, with the main advantages of low Global Warming Potential (ODP) and GWP (global warming potential (GWP) values of approximately 0 and 675. However, because this refrigerant is classified as a new refrigerant, its implementation is limited to air-conditioning and heat pumps. In this study, R32 was tested for cold-storage applications. The cold storage performance was studied with respect to the achieved temperature, power consumption, cooling capacity, and Coefficient of Performance without load. The testing was carried out in two ways: cold storage testing on a laboratory scale and direct testing on a 5 GT fishing boat. The performance results show that both tests on a lab scale and tests directly on a fishing boat without a load can reach a cold storage room temperature of approximately − -18°C. Meanwhile, the power consumption of the compressor supplied by photovoltaic power was 0.653-0.776 kW. The other evaluation parameters, such as the cooling capacity (Qe), heat rejection (Qc), and COP were shown around 4,98 kW, 5,94 kW, And 7,72 respectively. Based on the test results, R32 has the potential to be applied in cold storage. [ABSTRACT FROM AUTHOR]

This article presents the performance estimation of a single-stage vapor adsorption system employing various carbon-based adsorbents with ethanol refrigerant, coupled with a small-scale biomass-based heating unit for space cooling, refrigeration, and heat-pumping applications. A detailed parametric investigation highlights the effects of operating temperatures, and heat exchanger to adsorbent mass ratio on specific cooling energy (SCE), coefficient of performance (COP), uptake efficiency (ηu), and mass of adsorbent to combustion fuel (mad/mcf) to identify the suitable adsorbent and sorption bed designs for each application. The numerical findings reveal that the flat-finned tube (FFT) adsorber outperforms traditional-finned tube (TFT) and tube & shell-type (T&S) adsorbers, achieving 19% and 30% higher COP, respectively, with biomass carbon-ethanol pair. The H2-treated Maxsorb-III shows the greatest optimal cooling COP (0.73), followed by the biomass-carbon (0.72) for refrigeration and space cooling. For heat pumping applications, biomass carbon-ethanol achieves the highest heat pumping COP (1.84) at a desorption temperature of 90°C, surpassing H2-treated Maxsorb-III. Further, the biomass-derived activated carbon requires the lowest amount of adsorbent per unit mass of combustion fuel in the biomass heating unit. The present thermodynamic analysis is a precursor for optimization of the potential heat-exchanger geometries and operating parameters, with the high-performance carbon adsorbents. [ABSTRACT FROM AUTHOR]

The present study investigates the incorporation of renewable rooftop photovoltaic systems in fully electrified residential buildings and estimates the zero-energy demand building potential in relation to the climatic data of Greece. Specifically, the aim of the analysis is to calculate the maximum possible number of stories and therefore the total building height for a complete transformation to zero-net-energy building. The energy analysis, which is conducted using the DesignBuilder software, focuses on single-floor up to seven-story buildings. The importance of the present work lies in the acknowledgment of the diversity of the Greek residential sector, the adherence to national energy policies, and the European goal of fully electrified buildings. The examined case studies are equipped with electrically driven air-to-air heat pumps serving the space heating and cooling demands and with an air-to-water heat pump covering the domestic hot water requirements. The investigated locations are the four main cities of Greece, Athens, Thessaloniki, Chania, and Kastoria, which represent the country's four climatic categories. The conducted analysis allows for the mapping of the zero-energy building potential for the climatic data of Greece, demonstrating the possibility of striking a positive building energy balance through the integration of on-site renewable energy sources and the production of necessary electrical energy. The novelty of the present work lies in the identification of a key factor, namely, the building height, which determines the feasibility of transforming multifamily buildings into zero-energy buildings. According to the analysis results, the critical number of stories is calculated at six for Chania, five for Athens, four for Thessaloniki, and two for Kastoria. Regarding a three-story residential building, the incorporation of a renewable photovoltaic system can result in an annual surplus electricity production of 13,741 kWh (Chania), 10,424 kWh (Athens), and 6931 kWh (Thessaloniki), and a corresponding coverage of 100% (Chania), 69.0% (Athens), 38.9% (Thessaloniki) and 0% (Kastoria). [ABSTRACT FROM AUTHOR]

The radiant systems come to the fore due to energy saving potential and good integration. The effect of different forms of cold surfaces on human thermal comfort is focused on its application. A novel natural convection-radiant evaporator for heat pumps was developed and its influence on thermal comfort was investigated. A numerical model of the chamber with the evaporator was established and verified with experimental results. Thermal comfort experiments were conducted in a climate chamber and the influence of its asymmetric and uneven cold radiation on the thermal comfort was investigated. Due to the limitation of PMV in uneven radiation situations, the revised predicted mean vote (RPMV) was proposed to assess the thermal comfort in asymmetric and uneven radiation environments based on experimental results. Based on RPMV, the influence of the surface area and temperature of the evaporator on thermal comfort was numerically analyzed. The results indicate that indoor air temperature and relative humidity, RPMV increase with the increase of plate temperature, but decrease with an increase in plate area. The most favourable indoor thermal comfort environment was obtained at an indoor air temperature of 28°C and relative humidity of 50%, which is 2°C higher than traditional air conditioning system. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Chinese Institute of Food Science & Technology is the property of Journal of Chinese Institute of Food Science & Technology Periodical Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Thermoacoustic air-to-water air source heat pumps (TAWASHP) are the eco-friendly, simple, compressor less, low cost and likely looking future substitute for the existing compressor-based heat pumps. In this work, the design optimization of the 1-kW TAWASHP with helium for the temperature difference of 15 to 70 K for pumping heat from the atmospheric air to water using the linear thermoacoustic concepts was discussed. The optimized design can fit for both cooling and water heating applications without wasting the heat rejection to the surrounding atmosphere, rather supplied to the insulated hot water tank. The optimized one-fourth wavelength resonator TAWASHP shows the coefficient of performance of 1.1 to 2.34. The theoretical results are validated with the DeltaEC software results, and the results are in concurrence with each other. The DeltaEC predicts the TAWASHP can supply 1.55 to 3.35 kW of heat to water, which is equivalent to 37.3 to 80.3 kWh of heat energy per day. [ABSTRACT FROM AUTHOR]

Thermoacoustic heat pumps are a promising heating technology that utilizes medium/low-grade heat to reduce reliance on electricity. This study proposes a single direct-coupled configuration for a thermoacoustic heat pump, aimed at minimizing system complexity and making it suitable for domestic applications. Numerical investigations were conducted under typical household heating conditions, including performance analysis, exergy loss evaluation, and axial distribution of key parameters. Results show that the proposed thermoacoustic heat pump achieves a heating capacity of 5.7 kW and a coefficient of performance of 1.4, with a heating temperature of 300 °C and a heat-sink temperature of 55 °C. A comparison with existing absorption heat pumps reveals favorable adaptability for large temperature lift applications. A case study conducted in Finland over an annual cycle analyzes the economic and environmental performance of the system, identifying two distinct modes based on the driving heat source: medium temperature (= 250 °C) and low temperature (< 250 °C), both of which exhibit favorable heating performance. When the thermoacoustic heat pump is driven by waste heat, energy savings of 20.1 MWh/year, emission reductions of 4143 kgCO2/year, and total environmental cost savings of 1629 €/year are obtained. These results demonstrate the potential of the proposed thermoacoustic heat pump as a cost-effective and environmentally friendly option for domestic building heating using medium/low-grade heat sources. [ABSTRACT FROM AUTHOR]

The traditional evaporator of water source heat pump system is easy to freeze when the water source temperature is too low in winter. A novel ice source heat pump system is proposed, which can use low temperature surface water to supply heat to buildings. One of the key problems for safe transportation is velocity range of ice slurry in ice outlet pipeline. In order to study the critical flow velocity of ice slurry in the pipe, an Euler model of horizontal straight pipe and 90° elbow pipe were established by Fluent software. The influence of five factors on the critical flow velocity of two kinds of pipes, including initial ice packing fraction, ice particle size, pipe diameter, length of straight pipe and radius curvature of elbow was studied. It found that the initial ice content should be controlled from 10% to 15%. The inlet flow rate was 20% higher than the critical flow rate under the most unfavorable condition. Ice particle size was less than 0.2 mm. The total length of ice discharge pipeline was less than 50 m. Curvature radius of the bend should be met the minimum requirements of the specification of the pipe used. [ABSTRACT FROM AUTHOR]

Copyright of Industrial Water Treatment is the property of CNOOC Tianjin Chemical Research & Design Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The deteriorating thermal environment of tunnels and the increase in energy consumption of environmental control systems has become highlights in the subway field. In existing research related to analysis of subway tunnel thermal environments and thermal accumulation; there is no predictive law that accounts for thermal accumulation or the long-term change in subway tunnel thermal environments. In this study, a combination of simulations and experiments is used. First, the long-term evolution of tunnel thermal environments with and without thermal interference are predicted and analyzed. Then, the changes in the tunnel thermal environment after the use of capillary heat exchangers are explored. The research results indicate that the model of the system has high accuracy and reliability. When there is a capillary heat exchanger installed in the subway tunnel, the anti-seasonal heat storage characteristics of the system result in the tunnel temperature increasing significantly in summer and decreasing significantly in winter, with a small decrease in the average annual temperature. This study provides a theoretical reference for environment-based subway tunnel construction and the comprehensive utilization of tunnel waste heat. [ABSTRACT FROM AUTHOR]

There is an increasingly rich literature on the decarbonisation of heat and the evolution of heat networks. This paper investigates whether a novel fifth Generation District Heating and Cooling Network (5GDHC) could be retrofitted to an existing National Health Service (NHS) hospital campus for the purpose of heating and cooling. The building load was simulated and input into a custom-written script to carry out a series of parametric studies and optimise design options. The model was calibrated against site data available from hospital facilities management. The research found that it is feasible to use a 5GDHC consisting of a large single mass of water to utilise inter-seasonal thermal storage. A natural water resource such as an aquifer was not required. The model tested sizing options and found that larger thermal storage, heat pumps and chillers reduce operating costs and improve flexibility. The paper closes with a discussion of the practical factors in retrofitting 5GDHC networks to a densely occupied and highly constrained campus environment. The findings are novel in further describing the circumstances for which 5GDHC networks are suitable. [ABSTRACT FROM AUTHOR]

Air-source heat pumps (ASHPs), as an active device, are widely used in building heating and cooling processes. However, in severe cold regions, they face reduced heating efficiency and frosting problems in winter. This paper proposes a new heating solution by coupling an ASHP with passive heating systems. It combines an ASHP with passive sunrooms and heat storage systems for heating. Through software simulations and mathematical modeling, the new scheme is compared and analyzed against traditional ASHP solutions to explore the performance of this scheme in rural houses in severe cold regions of China during winter. According to simulation and calculation analysis, on the coldest day of winter, the coupling scheme can provide approximately 99.41 kWh of heat to the indoors, which exceeds the 86.67 kWh required to maintain an indoor temperature of 20 °C. The system's power consumption is 36.96 kWh, which is 66.88% lower than that of traditional heat pump heating. The study shows that the coupling system of an ASHP and passive heating has a good heating effect in severe cold regions. For the situation of insufficient solar energy at night, the design of phase-change materials and heat storage media can meet heating needs throughout the day. [ABSTRACT FROM AUTHOR]

The forthcoming implementation of national policies towards hydrogen blending into the natural gas grid will affect the technical and economic parameters that must be taken into account in the design of building heating systems. This study evaluates the implications of using hydrogen-enriched natural gas (H2NG) blends in condensing boilers and Gas Adsorption Heat Pumps (GAHPs) in a residential building in Rome, Italy. The analysis considers several parameters, including non-renewable primary energy consumption, CO2 emissions, Levelized Cost of Heat (LCOH), and Carbon Abatement Cost (CAC). The results show that a 30% hydrogen blend achieves a primary energy consumption reduction of 12.05% and 11.19% in boilers and GAHPs, respectively. The presence of hydrogen in the mixture exerts a more pronounced influence on the reduction in fossil primary energy and CO2 emissions in condensing boilers, as it enhances combustion efficiency. The GAHP system turns out to be more cost-effective due to its higher efficiency. At current hydrogen costs, the LCOH of both technologies increases as the volume fraction of hydrogen increases. The forthcoming cost reduction in hydrogen will reduce the LCOH and the decarbonization cost for both technologies. At low hydrogen prices, the CAC for boilers is lower than for GAHPs; therefore, replacing boilers with other gas technologies rather than electric heat pumps increases the risk of creating stranded assets. In conclusion, blending hydrogen into the gas grid can be a useful policy to reduce emissions from the overall natural gas consumption during the process of end-use electrification, while stimulating the development of a hydrogen economy. [ABSTRACT FROM AUTHOR]

Achieving a zero-emission building heating sector requires numerous strategies and detailed energy planning, in order to identify the optimal decarbonisation pathway. This work aims to assess the impact of district heating expansion and the implementation of energy-saving measures on the decarbonisation of the Italian building stock by 2050, analysing their combined impact, reciprocal effects, and technical–economic implications on the entire national energy system. The scenarios have been implemented and simulated with the H2RES software, a long-term energy planning optimisation model, built for the Italian national energy system. Results indicate that it is possible to decarbonise the heating system in an efficient and cost-effective manner by the year 2040. Heat pumps represent the optimal technology at both centralised and decentralised levels. District heating expansion is a priority for the decarbonisation of the building stock, allowing us to reduce costs, exploit thermal storage systems and provide system flexibility. In the best scenario, 40% of the Italian heat demand can be supplied by fourth-generation district heating. Energy-saving measures can reduce heat demand and primary energy but at higher annual costs and with a significant increase in investment. The combined simulation of the strategies within an optimisation model of the entire energy system enables the accurate assessment of the real impact of the various measures, considering their reciprocal effects and technical–economic implications. [ABSTRACT FROM AUTHOR]

Elastocaloric cooling technology has the prospect of becoming a commercialized green alternative to current vapor-compression technology, and the systematic characterization of the elastocaloric effect and microstructure has become increasingly significant for the optimization of elastocaloric coolers and heat pumps. In this work, a comprehensive elastocaloric effect characterization for a dog-bone shaped NiTi sheet with a thickness of 0.5 mm was performed for the application in a compact continuous rotating bending elastocaloric cooler. The elastocaloric effect was found to be nearly identical under Brayton-like and sinusoidal force-controlled cyclic tensile loadings. The maximum adiabatic temperature change values of 31 and 23 K were recorded in Brayton-like cyclic loadings under maximum applied stress of 600 and 400 MPa, respectively, with an applied strain rate of 0.1 s−1. During fatigue tests, large applied stress (>600 MPa) and high applied strain rates (>0.1 s−1) tended to result in premature failure of the NiTi sheet samples. In the continuous rotating bending elastocaloric cooler, the sheets generated a temperature span of 6 K between the copper heat sink and heat source. The results of this work provide a set of thermophysical property data for the elastocaloric solid refrigerant and insights for the optimization of structural and operational parameters in elastocaloric coolers and heat pumps. [ABSTRACT FROM AUTHOR]

Online condition-monitoring techniques that are used to reveal incipient faults before breakdowns occur are typically data-driven or model-based. We propose the use of a fundamental physics-based thermofluid model of a heat pump cycle combined with deep learning-based surrogate models and parameter identification in order to simultaneously detect, locate, and quantify degradation occurring in the different components. The methodology is demonstrated with the aid of synthetically generated data, which include the effect of measurement uncertainty. A "forward" neural network surrogate model is trained and then combined with parameter identification which minimizes the residuals between the surrogate model results and the measured plant data. For the forward approach using four measured performance parameters with 100 or more measured data points, very good prediction accuracy is achieved, even with as much as 20% noise imposed on the measured data. Very good accuracy is also achieved with as few as 10 measured data points with noise up to 5%. However, prediction accuracy is reduced with less data points and more measurement uncertainty. A "backward" neural network surrogate model can also be applied directly without parameter identification and is therefore much faster. However, it is more challenging to train and produce less accurate predictions. The forward approach is fast enough so that the calculation time does not impede its application in practice, and it can still be applied if some of the measured performance parameters are no longer available, due to sensor failure for instance, albeit with reduced accuracy. [ABSTRACT FROM AUTHOR]

Efficient and reliable utilization of renewable energy at the user's end is the key to achieving a low‐carbon life. This paper proposed a new distributed energy system around the comprehensive utilization of solar energy by integrating solid oxide fuel cell (SOFC), energy storage equipment, photovoltaic thermal (PVT) collector, and heat pump. By integrating the use of SOFC and PVT, we can further minimize reliance on fossil fuels, while employing the coupling of PVT and heat pump effectively mitigates the inherent challenges of solar energy's variability and intermittency, all while enhancing overall system efficiency. On this basis, we apply the heat current method to construct a cross‐scale heat current model of the components and the system by considering the energy transfer, conversion, and storage characteristics of the system. By employing this model, we simulate the system's operation throughout an entire typical day, assess the COP enhancement of the PVT‐coupled heat pump system, analyze the influence of diverse operating conditions on daily system performance, and evaluate the economy of the energy storage devices in the system. [ABSTRACT FROM AUTHOR]

Copyright of Food & Fermentation Industries is the property of Food & Fermentation Industries and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article proposes a heating method based on heat pump technology to address the large amount of low-grade waste heat generated by a certain type of ultra-high voltage direct current (UHVDC) converter valve. Thermal performance calculations for two systems, a basic vapor compression heat pump system (BVCHPS) based on thermal expansion valve throttling and an ejector-enhanced heat pump system (EEHPS) are analyzed. The research results show that the EEHPS exhibits superior COP and exergy efficiency when generating hot water above 80 °C using a heat source below 50 °C. Additionally, mathematical modeling analysis identifies optimal structural parameters such as nozzle throat diameter, throat area ratio, and nozzle outlet diameter for the ejector in its design state. The low-temperature waste heat recovered from the UHVDC converter valves can be further used in engineering applications such as heating, refrigeration, seawater desalination, and sewage treatment. [ABSTRACT FROM AUTHOR]

Characterizing the optimal operating parameters for a heat pump with a specific refrigerant is paramount, as it provides valuable guidance for refrigerant selection. The temperature mismatch between cold and hot fluids in the evaporator and condenser can lead to degraded thermal performance in heat pumps with large temperature variations. To address these two key issues, we selected several pure refrigerants with varying critical temperature levels for use in a large temperature variation heat pump configuration. The corresponding thermal performance was then investigated using the Ebsilon code under fixed temperature lift conditions as the operating temperature varied. It indicates that the maximum coefficient of performance (COP) is typically achieved when the deviation factors of temperature and pressure from their critical parameters fall within the ranges of 0.62~0.71 and 0.36~0.5, respectively. Our research recommends the binary refrigerant mixture of R152a/R1336mzz(z) (COP = 3.54) for the current operating conditions, as it significantly improves thermal performance compared to pure R1336mzz (z) (COP = 2.87) and R152a (COP = 3.01). Through research on the impact of the compositional ratio of R152a/R1336mzz(z) on the thermal performance of the heat pump, we found that that the optimal ratio of R1336mzz(z) component to R152a component is 0.5/0.5. This study offers valuable guidance for selecting the most suitable refrigerants for heat pumps in practical engineering design scenarios. [ABSTRACT FROM AUTHOR]

The escalating energy demands in buildings, particularly for heating and cooling demands met by heat pumps, have placed a growing stress on energy resources. The bi-functional thermal diode tank (BTDT) is proposed as thermal energy storage to improve the heating and cooling performances of heat pumps in both summer and winter. The BTDT is an insulated water tank with a gravity heat pipe (GHP), which can harvest and store heat passively from sun radiation and the external environment during the daytime. In summer, it harvests and stores cold energy from the air and night sky during the daytime. The performance of the BTDT-assisted heat pump (BTDT-HP) system in Adelaide, Australia, during the 2021–2022 summer and winter seasons was evaluated by conducting a TRNSYS simulation. This study revealed that the BTDT-HP system outperformed the reference ASHP system, where up to 8% energy in heating and 39.75% energy in cooling could be saved. An overall reduction in the energy consumption of 18.89% was achieved. Increasing the BTDT volume and GHP panel area enabled the tank to store more thermal and cold energy across the winter and summer seasons, thereby improving the system's performance. The maximum ESPs were found to be 31.6% and 41.2% for heating and cooling for the study case under optimal conditions. When the GHP panel area was fixed at 15 m2, the BTDT volume should be at least 28 m3 for the BTDT-HP system, boasting cooling and heating capacities of 40 kW and 43.2 kW, to achieve positive energy savings. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Featured Application: The main application of this paper is to review and improve a model that enables the use of water heaters by small electricity customers in electricity markets and services in the short and medium term. For this goal, it is necessary to review the service of loads to avoid customer discomfort and the way control mechanisms work, usually thermostats. To guarantee a minimum level of accuracy in the flexibility of the response, the understanding of heat and electric processes in the load is a cornerstone for the participation of these appliances. This must be done by comprehensive validation of the model in different conditions, including water draws, temperature, and load control. To exemplify the potential of the model, an application in a prosumer scenario is presented. Residential segments are of the greatest interest from the point of view of Demand-Side Resources and Decarbonization. Main end-uses such as water heaters, heating, and cooling have interesting opportunities: first, they can store energy, and this is relevant for the integration of renewables. Second, they are candidates for efficiency and electrification, increasing their demand share and the flexibility of demand. This paper aims to formulate an elemental Physical-Based Heat Pump Water Heater model that will enable the use of these energy-efficient appliances through aggregation in complex products, considering the advantages for demand and supply sides. Simulation results show that the individual performance is quite accurate and that the proposed model is flexible enough to be used to take more profit from energy markets or to easily respond to fast-occurring events. The model can be easily aggregated and used to obtain baselines, an important point for Demand Response evaluation. Results also demonstrate that demand–supply coordination and balance can be improved using these models to reduce or mitigate the risks and volatility of renewables without inducing a noticeable loss of service. Consequently, the contribution of this responsive load can be modelled through this methodology, making the engagement of more customer segments in Demand Response policies more credible and deploying new segments, such as prosumers. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the impact of solar radiation intensity on the performance of direct-expansion solar PVT heat pump systems. To this end, an experimental setup was constructed for direct-expansion photovoltaic (PVT) solar heat pump water heating systems and photovoltaic (PV) power generation systems. The system performance and main parameters were analyzed and discussed under different solar radiation intensities. The winter experiments in southern China revealed that the exhaust temperature of the heat pump unit varied considerably under clear conditions, while the back temperature remained stable, fluctuating between approximately −13.5 °C and 24 °C. In contrast, the power generation of PVT panels increased with the increase in radiation intensity, from 78.33 W to 122.68 W, for an increase of 56.6%. Furthermore, the total electricity generation of the PVT panels was higher than that of PV panels, with an increase of 8.7–8.3%. Nevertheless, discrepancies between experimental and theoretical data were observed, particularly under overcast conditions, where the back panel temperature error was pronounced. Additionally, the system exhibited enhanced stability at elevated temperatures in comparable environments, accompanied by an improvement in the system's coefficient of performance (COP) by 5.67%. [ABSTRACT FROM AUTHOR]

This experiment mainly used in-shell fresh peanuts as the main raw material and adopted heat pump drying technology to dry peanuts. The effects of different material temperatures, loading masses, and air velocities on drying characteristics and peanut kernel nutritional quality were compared. Results showed that during drying, the drying moisture ratio decreased exponentially with increasing drying time, and the drying rate decreased with time. With the increase in material temperature, the drying time decreases, and the unit energy consumption first decreases and then increases. With the increase in loading mass, the drying time increases, and the unit energy consumption first decreases and then increases. Air velocity had no significant effect on drying time and unit energy consumption. The material loading had no significant effect on the protein, fat, oleic acid, linoleic acid, and amino acid contents in peanut kernels. The material temperature and air velocity had a significant effect on the nutritional quality of peanut kernels. The acid value and peroxide value of the dried peanut kernels met the national standard. When the hot air temperature was 45 °C, the germination potential and rate of peanut kernels were the highest, and the material loading and air velocity had no significant effect on the germination rate. In conclusion, setting the drying conditions to a hot air temperature of 45 °C, a single loading amount of 1 000 g, and an air velocity of 1.2 m/s resulted in better drying characteristics and quality of peanut kernels, with a shorter drying time (10.0 h) and the lowest unit energy consumption (11.01 kW·h/kg). [ABSTRACT FROM AUTHOR]

The selection of water temperature regulation equipment plays a crucial role in the design of workshops. At present, the choice of water temperature control equipment is usually based on the volume of the fish pond and thermal parameter calculation, combined with aquaculture experience. Empirical formulas only work in specific conditions due to factors like the environment, climate, and fish types,resulting in inaccurate equipment selection outcomes. Recognizing this limitation, this paper proposes to apply CFD simulation of the temperature field to accurately calculate the heat exchange value between indoor air and water, thereby predicting the heat exchange values during aquaculture activities in the aquaculture workshop. providing a new approach for equipment selection. This paper selects a puffer fish breeding workshop in Dalian as the simulation object, establishing a 3D unsteady-state Computational Fluid Dynamics model. The model considers outdoor temperature, solar radiation, and phase-change heat transfer in water. Comparison with experimental data reveals a root mean square error of 0.46°C for the simulated results. During summer, the highest cooling load occurs at 16:00, reaching 94.6 kW. It is recommended to employ the Daikin GCHP-40MAH ground source heat pump as the water temperature control equipment. CFD simulation validates its effectiveness in shaping the indoor temperature field post-installation. the investment in water temperature control equipment can be reduced to a certain degree. This provides a reference value for the selection of water temperature equipment in aquaculture workshops. [ABSTRACT FROM AUTHOR]

Heat transfer in evaporation units play a vital role in the design and optimization of heat pumps and refrigeration systems. Existing correlations are often limited to the respective heat transfer surface. Furthermore, the majority of correlations reported have a lack of reliable validation beyond the test of their ability to describe the data they have been fitted to. In the present study, the heat transfer in case of flooded evaporation on an enhanced tube was examined for two refrigerants and propane. The experimentally measured data were used to develop a new correlation for the shell‐side heat transfer. The correlation was assessed on a separate test set, not utilized in the process of model development. The correlation and procedure are reliable and transferable tools for estimation of heat transfer in enhanced tube evaporators for refrigerants. [ABSTRACT FROM AUTHOR]

Model predictive control (MPC) is a promising approach for optimizing the performance of borehole heat exchangers (BHEs) in ground-source heat pump systems. The central element of MPC is the forward model that predicts the thermal dynamics in the ground. In this work, we validate the prediction accuracy of four BHE modeling approaches against real-world measurement data across various operational events and timescales. We simulate the fluid temperature leaving a BHE using a fully discretized 3-D numerical model, a resistance–capacitance model, a g-function model, and a hybrid model. The simulated temperatures are compared to measured temperatures using three validation metrics that quantify temperature offset, noise, and accuracy. The main reason for a mismatch between measured and modeled temperatures is a temperature offset of the simulated temperature. To remove this effect, the models were calibrated for their most sensitive parameter, the ground temperature, and their prediction accuracy over 4 years was evaluated. Thereby, model calibration seems to be a viable solution to account for an unknown load history. The results show that the resistance–capacitance model provides decent predictions in the short term and the g-function model in the long term. However, both models are strongly dependent on accurate calibration. The hybrid model provides the most accurate short and long-term predictions and is less dependent on calibration. Still, its integration into optimization syntax poses challenges compared to the other models. Although not yet applied in model predictive control, the hybrid model stands out as a promising choice for optimizing BHE field operations across various timescales. [ABSTRACT FROM AUTHOR]

The paper deals with the development of a microprocessor-based system for load monitoring of electric power systems based on IoT technologies. An overview of scientific research in the field is given. A microprocessor-based system for measuring climatic parameters as well as voltage and current has been developed as a pilot prototype. The system is designed to provide effective monitoring and control of the heat pump and related equipment. An information scheme is constructed that describes the interaction between components of the power system load monitoring system and the information flows from the sensors to the final data storage system. [ABSTRACT FROM AUTHOR]

The heat pipe radiator directly driven by heat pump heating system has the advantages of fast heat transfer and high energy efficiency. Based on the empirical heat transfer formula, the heat and mass transfer process in the heat pipe radiator was studied. The key parameters in the empirical heat transfer formula were derived by combining with the experimental data. The distribution of the thickness of the condensate film and the heat transfer coefficient in the height direction of the heat pipe radiator was analyzed. The influence of the working fluid condensate mass and vapour mass in the heat pipe radiator was investigated. The results showed that the thickness of the liquid film changes from the bottom of 0.1110 mm to the top of 0.0594 mm along the height of the heat pipe. The minimum charge of working fluid is 1.78 kg to 1.81 kg and the heating COP of the system still reach to 3.14 even at the outdoor temperature of -12.6 °C. [ABSTRACT FROM AUTHOR]

The demand for heating and air conditioning is rising due to rapidly changing climatic conditions. The market for heat pumps and air conditioning systems is seeing a steady increase in low global warming potential. There is a growing need to use environment-friendly refrigerants. Contemporary Refrigerants (HCFCs) such as those found in heat pump air conditioning systems have the potential to cause global warming and ozone depletion. Using more environmentally friendly refrigerants, including hydrocarbon and blend refrigerant mixtures, is one way to lower Global Warming Potential (GWP) and Ozone depletion potential. This study examines the performance of several alternative refrigerants, including R32, R134A, R410A, R22 and R290. To examine the performance of R290, theoretical and simulation results are compared for various refrigerants while taking into account several performance parameters, including the refrigerant energy efficiency ratio, mass flow rate, coefficient of performance, cooling capacity and compressor work for One Ton of Refrigeration (1TR) air conditioners. One player with a very low GWP is R290. However, the only drawback is that it can catch fire and is hazardous to use in splittype commercial heat pump air conditioning applications. The environmental and thermo physical properties of R290 are significantly better than those of other materials, according to theoretical and simulation studies utilising Cool Pack software, hence it is a viable replacement. [ABSTRACT FROM AUTHOR]

Drying and sanitising equipment has been very common in industrial plants since the pandemic. These are devices that consume significant amounts of energy. The best solution is to use a drying chamber equipped with a heat pump, which allows partial recovery of the energy. In the design of the drying chamber, the drying time is important, which depends both on the parameters of the heat pump itself, and the geometry and airflow of the drying chamber. The geometry and airflow supply should be arranged to ensure a uniform distribution of velocity throughout the drying area. For this purpose, the use of CFD simulations has been proposed. A model was developed in ANSYS/FLUENT where all model parameters, including the optimal mesh density, turbulence models, etc., were determined. The model was verified on the experimental results of the basic design of the chamber. Then an innovative design was proposed that was modelled and optimised in terms of the distribution of the inlet's perforation. The final design was made, and, at the same time, the simulation's results were verified by measuring the velocity of airflow in the new design. Together with the optimisation of the heat pump, this made it possible to reduce the drying time by 50%, with a simultaneous reduction in the energy consumed. [ABSTRACT FROM AUTHOR]

A large number of ground-source heat pump (GSHP) systems have been used in residential and commercial buildings throughout the world due to their attractive advantages of high energy and environmental performances. In particular, GSHPs constitute a proven renewable energy technology for space heating and cooling. This paper provides a detailed literature review of the primary aspects of GSHP systems. These include the technological characteristics of HPs and the main types and variations in GSHPs, along with their environmental impact. Other aspects addressed are the integration of GSHPs with other systems, as well as their optimal design and control and energy analysis. The important aspect of the system's performance is also dealt with through case studies and also the barriers hindering the further adoption of GSHPs in buildings. Two important challenges for the adoption of GSHPs is their cost and environmental efficiency. Studies have shown that GSHPs can reach a >>24% lower environmental impact than air-source HPs, while today's technology can allow for a payback period for installing a GSHP of <<5 years. Finally, based on the above review, the future challenges and prospects for the successful uptake of GSHPs is discussed. It seems that through the right steps, the wide adoption of GSHPs as an important form of 'implemented' renewable energy system can become a reality. [ABSTRACT FROM AUTHOR]

The LDR-50 low-temperature nuclear reactor is designed for the Finnish and European district heating markets, as an environmentally sustainable heating option for the 2030s. While the carbon footprint of conventional electricity-producing reactors is known to be small, there have been no comprehensive studies on the emission reduction potential when the technology is applied to the heating sector. This paper aims to fill this knowledge gap by means of life cycle assessment (LCA) analysis. The carbon footprint of the LDR-50 heating plant is evaluated, and compared to conventional heating fuels, direct electric heating, and heat pumps. The results of the analysis show that the life cycle CO2 emissions are low, although there are still significant uncertainties related to the construction phase, due to missing data. In addition to carbon footprint, the analysis is also extended to other adverse environmental impacts. It is concluded that significant reductions in CO2 emissions can be achieved by replacing fossil heating fuels with nuclear energy. The technology is considered a viable option alongside biofuels and heat pumps. The overall environmental impacts are low, and the production does not compete for low-carbon electricity or scarce natural resources. [ABSTRACT FROM AUTHOR]

Deep geothermal energy is a sustainable and renewable spacing heating source. Although many studies have discussed the design optimization of deep borehole systems, few have accomplished optimization and in-depth analysis of system operation control. In this study, an analytical model of the U-type deep borehole heat exchanger is proposed, and the average relative error between the simulated outlet temperatures and experimental data is −3.2%. Then, this paper presents an integrated model for the operation optimization study of the U-type deep-borehole ground source heat pump system. The optimal control of flow rate is adopted to match the variation in heating load. Compared with the constant-flow rate (110 m3/h) operation mode, the variable flow rate method reduces the power consumption of the heat pump and circulating pump by 22.1%, from 288,423 kW·h to 224,592 kW·h, during 2112 h of operation. In addition, the system has a larger RHS and COP when the thermal conductivity of the backfill material increases. When the borehole depth increases by 200 m from 2300 m, the energy consumption of the circulating pump will drop from 85,844 kW·h to 56,548 kW·h. The COP of the heat pump unit will decrease approximately linearly as the heating load increases, and the total power consumption will increase accordingly. This work can provide guidance for the design and optimization of U-shaped GSHP systems. [ABSTRACT FROM AUTHOR]

• The article introduces a novel semi-empirical model for a TEV operating with R290. • No prior experimental work was found involving TEV operating with R290 in DX-SAHP. • The article emphasizes a careful data collection process encompassing 150 experiments. • The multiple linear regression resulted in a R² of 0.9648 with predictions not exceeding more than 15 % deviation. • The model was applied and compared with 44 experiments from the literature, resulting in a deviation of less than 15 %. The expansion device plays a crucial role in the operation of heat pumps and refrigeration systems, making its study integral to advancements in the fields of refrigeration and heating. Among various expansion devices, the Thermostatic Expansion Valve (TEV) stands out due to its rapid response time and mechanical nature, which grants it high control capacity over refrigerant superheating. In this study, was developed a semiempirical mathematical model for a TEV incorporated in a DX-SAHP utilizing R290. The research was carried out in an experimental way, conducted using a fully instrumented DX-SAHP. A series of experiments tested different operational modes for water heating, subject to varying solar radiation intensities. A uniform methodology collected operational parameters, resulting in 150 experiments. The semiempirical model creation involved combining basic equations from the literature describing TEV operation and formulating an equation using multiple linear regression based on experimentally evaluated parameters. These parameters included solar radiation incidence, inlet and outlet pressures, and superheating degree. The regression model achieved an adjustment higher than 96 %. Combining this regression with equations suggested by previous researchers, resulted in a model with an adjustment exceeding 94 %. Furthermore, this study culminated in the derivation of a generalized model primed for broad application across various heat pump configurations for water heating purposes. Notably, the model underwent rigorous validation across a separate set of experiments, reaffirming its reliability and versatility. While excelling in steady-state operations, the model's transient data analysis falls short, as intended. [ABSTRACT FROM AUTHOR]

• Focuses on thermophysical properties of propylene glycol solutions at low temperatures. • Experimental thermal conductivity results are higher than ASHREA data. • Experimental viscosity results are lower than ASHREA data. • Experimental specific heat capacity curves do not have the linear trend as most known databases. • Solutions with concentrations below 25 wt-% have higher specific heat capacity than water. More than 1.7 million ground source heat pumps are currently in operation in the European Union and a large majority of systems is using propylene glycol as secondary fluid. In this study the thermophysical properties of propylene glycol solutions with specific freezing points between −5 and −50 °C are investigated at low temperatures of interest for refrigeration and heat pump applications. The experimentally determined data are compared to a large number of data from the literature. It has been found that the freezing point results for all concentrations were in very good agreement with both Melinder (2010) and ASHRAE (2021) data. Moreover, the literature data and present study for concentrations above 40 wt-% have different density curve slopes compared to ASHRAE data. The viscosity results for concentrations below 40 wt-% were up to 21.5 % higher than ASHRAE data and the viscosity results for solutions with concentrations above 40 wt-% were lower by up to 9.7 %. The thermal conductivity results for concentrations above 40 wt-% were 10 % higher than ASHRAE (2021) data. The experimental specific heat capacity curves and other studies do not have the same linear trend as Melinder (2010) and ASHRAE (2021) data. This difference indicates that currently available ASHRAE data have been indirectly computed from thermal conductivity data or that they have not been fully experimentally validated. Finally, more studies are required to investigate concentrations below 25 wt-% to identify solutions with higher specific heat capacity than water that could be of interest for specific applications. [ABSTRACT FROM AUTHOR]

This article explores the use of heat pumps as a topic in chemistry education. Heat pumps are both politically controversial and provide an opportunity to teach students about energy principles. The article presents an experiment using a syringe filled with pentane to demonstrate the relationship between pressure and temperature. Safety precautions are emphasized due to the flammability and toxicity of pentane. The experiment aims to help students understand the operation of heat pumps and refrigerators. The article concludes by discussing the results of the experiment and the need for additional teaching approaches to enhance student understanding. [Extracted from the article]

This paper studies the optimization design of capillary heat exchangers and their innovative engineering applications in buildings. The purpose of this study is to use a capillary heat exchanger as the front-end device of the heat pump in coastal areas to extract energy to facilitate the application of renewable energy in buildings. Firstly, in this paper, the main factors of capillary heat transfer efficiency were explored in areas near the coast. Secondly, for the sake of improve the heat transfer efficiency of the capillary heat exchanger, numerical calculations were carried out on the heat transfer of the capillary in the case of inconsistent operating patterns in the summer and winter months, respectively. The results showed that when the daily working time of the capillary heat exchanger was 8 hours, the temperature difference of the capillary inlet and outlet was 2.1 ℃. And the heat transfer rate was 87.1 W/m² . In summer, the temperature difference of the capillary inlet and outlet was 2.6 ℃. And the heat transfer rate was 107.8 W/m² . This article helps to promote innovative and sustainable technologies in coastland development, such as capillary heat exchangers and heat pumps, which could used in renewable energy extraction and building utilization in near coastal areas. [ABSTRACT FROM AUTHOR]

To enhance the product quality, manufacturers of dried fruits are dedicated to developing reliable methods for assessing ripeness. In this study, a densimetric flotation method was employed to categorize mulberries into five distinct ripening stages (D1–D5, 0.905–1.055 g/cm³). The influence of ripening on mulberry water status, distribution, microstructure, drying characteristics, and product quality was examined. Heat pump drying, utilizing a temperature of 60 °C, relative humidity of 15%, and air velocity of 2 m/s, was employed as the drying technique for mulberries. As ripening progressed, the water binding capability initially decreased and then increased. Simultaneously, water distribution and cell microstructure shifted, resulting in an initial reduction followed by an extension in drying time. The drying time initially decreased and then increased with increasing maturity, with D4 fruits displaying the shortest drying time (13.9 h). This was 35.05%, 24.04%, 20.14%, and 6.47% shorter than the drying times observed in stages D1, D2, D3, and D5, respectively. Ripeness significantly affected the volatile composition, color, texture, and sensory attributes of dried fruits. D1 fruits were not suitable for drying due to their intact cellular structure, lengthy drying time, and poor sensory quality of the resulting product. Conversely, D4 and D5 fruits exhibited shorter drying times and their products possessed a robust fruity aroma, improved palatability, and overall acceptance. This rendered them ideal candidates for the drying process. The findings of this research have practical implications for effective identification and drying procedures during mulberry ripening. [ABSTRACT FROM AUTHOR]

Current energy efficiency regulations have led to the development of heat pumps equipped with variable speed compressors (VSC) and electronic expansion valves (EEV). To reduce the amount of refrigerant charge, heat pump manufacturers are developing units without a liquid receiver. As a result, the amount of refrigerant charge has a direct impact on the unit performance and needs to be optimized. Previous studies have shown the existence of an optimum refrigerant charge that maximizes the COP at a given operating condition. However, with VSC it is not clear if the optimum charge at a given compressor speed is the adequate one at other speed values. This paper analyzes the effects of the refrigerant charge amount on the performance of a brine-to-water heat pump equipped with a VSC and an EEV. For a given compressor speed, the variation of the COP with the charge showed similar trends and an optimum refrigerant charge could be identified. The charge for the maximum COP changes slightly with the compressor speed. The seasonal coefficient of performance (SCOP) is proposed as a better metric for evaluating the optimum charge. Results show that the SCOP is quite stable with the refrigerant charge. [ABSTRACT FROM AUTHOR]

Striving for the highest quality food product in the shortest time with the least energy expenditure is the cornerstone of the food drying process. Furthermore, the geometric properties of the product significantly influence the efficiency of the drying process. Therefore, in this study, peach slices of three different thicknesses were dried in three different dryer types. The drying of peaches was carried out using a solar energy drying system, a thermal energy storage solar dryer, and a dryer with a heat pump. The drying performances of peach slices of three different thicknesses were investigated. Moisture extraction rates (MER), specific moisture extraction rates (SMER), and specific energy consumption (SEC), which relate to the amount of removed moisture and the amount of consumed energy at the end of the drying studies, were calculated. Food analyses, such as moisture content, color, texture, and water activity were performed. Considering the amount of energy consumed, it is seen that the heat pump system consumes more energy than the solar energy system. In addition, by using the heat storage system, the drying time is shortened, and the energy consumption is reduced. A decrease in SEC values was observed with the activation of the heat storage solar dryer. [ABSTRACT FROM AUTHOR]

We have proposed that galaxy formation is catalyzed by the collision of infalling and outstreaming particles from leaky, horizonless astrophysical black holes, most likely gravastars, and based on this gave a model for the disk galaxy scale length. In this paper we modify our original scale length formula by including an activation probability P for a collision to lead to nucleation of star formation. The revised formula extrapolates from early universe JWST data to late time data to within a factor of five, and suggests that galaxy dimensions should systematically get smaller as the observed redshift z increases. We also show that particles recycling through gravastars can lead to a reduction in the temperature of the surrounding gas, through a "heat pump" refrigeration effect. This can trigger galaxy formation through enhanced star formation in the vicinity of the gravastar. [ABSTRACT FROM AUTHOR]

Despite bioenergy playing an important role in producing a significant amount of renewable energy in the EU, there are several differing views of its future role, as illustrated in the European Parliament and society more generally. The aim of this paper is to investigate the barriers to advancing bioenergy use and prospects for the future of bioenergy in the EU. Whereas previous studies have focused on specific aspects of EU bioenergy, such as market structure, technological considerations, and individual forms of bioenergy, this study provides results from a survey analyzing several factors that are inhibiting overall bioenergy development throughout the EU. The results show that, in general, the growth of bioenergy use in the EU can be expected to continue, although there are many issues that need to be addressed by society and through policy implementation. The most important of these issues include the relationship between the future role of the fossil fuel using industry and bioenergy, addressing the inadequate and currently confusing level of policy support, and responding to the perception of low public acceptance, reflected by pressure from some nongovernmental organizations to reduce the use of bioenergy. The study shows that biomass is not always the best option in economic terms, and other options such as heat pumps powered by green electricity or natural gas can be more financially attractive. To ensure the continuing development of the bioenergy field in the EU, it is important to increase local policy support for bioenergy, decrease imports of fossil fuels from non‐EU countries, increase investment in the bioenergy sector, and engage in effective and fact‐based education about, and promotion of, bioenergy. [ABSTRACT FROM AUTHOR]

A common belief is that any closed, counterclockwise cycle on a pV diagram represents a refrigerator or heat pump. It has been established that this is not the case, but previous papers on this topic have made unnecessary assumptions about the temperatures of the energy reservoirs and about how the system exchanges energy with the reservoirs. Relaxing these assumptions leads to a wide array of unexpected behaviors. In some cases, the same pV cycle can be a heat pump, a cold pump, or a Joule pump simply by changing how the system is connected to the reservoirs. This paper explores the strange world of counterclockwise cycles. Editor's note: In this paper, author Randall Knight explores the rich behavior of counterclockwise thermodynamic cycles. A counterclockwise cycle can function as a heat pump or refrigerator, but this is not the only possibility. The choice of thermal reservoirs and the choice of which reservoir heat is absorbed from and exhausted to during the cycle affect the coefficient of performance and even the basic function of the device. The author illustrates these possibilities through an analysis of counterclockwise Carnot, Kelvin, Brayton, and Stirling cycles. The analysis includes interesting possibilities, such as a cycle that operates with a single reservoir, as well as practical applications like the role of heat exchangers. The surprising results of this analysis will likely be of interest to anyone who has studied thermodynamics, and the material can easily be incorporated into any course that includes thermodynamics, from introductory physics to graduate study. [ABSTRACT FROM AUTHOR]

The energy consumption of high carbon natural gas increases with the increase of carbon content when it is decarburized by the alcohol amine process. In order to reduce the energy consumption of high carbon natural gas, a carbon dioxide (CO2) capture coupled process (referred to as "coupled process") was proposed, which coupled the alcohol amine process (N-methyldiethanolamine as the absorbent) with inter-stage cooling, liquid rich shingle desorption, acid gas recompression heat pump and steam-mechanical recompression technology (MVR) heat pump processes. The key parameters, such as inter-stage flow cooling temperature, lean liquid throttling pressure, acid gas recompression pressure and regenerator bottom reboiler temperature, were analyzed by Aspen Hysys software, and the key parameters were optimized by response surface analysis and genetic algorithm. The results show that the inter-stage flow cooling temperature, the lean liquid throttling pressure, the acid gas compression pressure and the regenerator bottom reboiler temperature is 58 °C, 0.0844 MPa, 0.195 MPa and 92 °C, respectively. Compared with the combined process (membrane separation + alcohol amine method), the energy consumption of the coupled process is significantly reduced, and the unit energy consumption of decarbonization (the energy required to remove 1 t CO2) decreases from 1.338 GJ/t to 1.110 GJ/t. Compared with before optimization, the CO2 content (volume fraction) in the purified gas of coupled process after optimization decreases from 2.533% to 2.326%, and unit energy consumption decreases from 1.110 GJ/t to 1.074 GJ/t. [ABSTRACT FROM AUTHOR]

The CO2 phase change capture process has low regeneration energy consumption, but in actual production, the CO2 content (mole fraction, the same below) in flue gas generated by the upstream process is unstable, which can lead to changes in the overall energy consumption of the process. Therefore, it is necessary to study the adjustment strategies of the process parameters under different CO2 content of flue gas. Using Python to invoke Aspen Plus to simulate the near isothermal CO2 capture technology, and the effects of adsorption tower temperature (ta), desorption tower temperature (td), liquid/gas ratio (v), amine concentration (c) and desorption liquid circulation ratio (s) on the regeneration energy consumption and CO2 capture rate and the corresponding regulation strategies were analyzed. The results show that td has the most significant effect on CO2 capture rate, and the correlation coefficient is the highest (74.78%) when the CO2 content is 5.00%. ta has the most significant impact on regeneration energy consumption, and when CO2 content is 20.00%, its correlation coefficient is the highest (-55.26%). With the CO2 content increases from 5.00% to 20.00%, the regeneration energy consumption decreases from 2.35 GJ/t to 2.13 GJ/t under the condition that the CO2 capture rate is greater than 90.00%. In addition, ta, td, c and v should be adjusted accordingly according to CO2 content to ensure that CO2 capture rate is greater than 90.00% and the regeneration energy consumption is lowest. [ABSTRACT FROM AUTHOR]