Solution absorption energy storage is a new energy storage and release technology characterized by high energy storage density, low heat loss, good mobility, and long-term energy storage. Energy storage density and energy storage efficiency are the key indexes for measuring the energy storage capacity of absorption energy storage systems and the key parameters for evaluating the energy conversion efficiency of absorption energy storage systems, respectively. Based on thermodynamic principles, the energy storage characteristics and applicability of absorption energy storage systems were investigated using six types of absorption solutions under different conditions. The results show that both energy storage density and energy storage efficiency increase with an increase in heat source temperature and cooling water temperature and decrease with solution concentration. At a heat source temperature of 70-120 ℃ and condensing temperature of 24-36 ℃, NaOH-H₂O has the largest energy storage density and efficiency, CaCl₂-H₂O has the smallest energy storage density and efficiency, and LiBr-H₂O has the widest applicability of temperature range.

In this study, a phase-change heat-storage water tank with a flat-plate storage plate was designed with phase-change materials. A heat-storage water tank model was constructed using the same staggered arrangement. Experiments and simulations were used to investigate the heat storage and discharge performances of a flat-plate-filled phase-change heat-storage water tank and the influence of the discharge flow rate on the heat release performance of the change materials. The role of different discharge flow rates in improving the heat release performance of phase change materials is discussed. The results show that filling a 98 L water tank with 12.15 L of phase change materials in a flat plate manner increased the heat storage capacity of the water tank by 17.91% while improving the stability of the system operation. By analyzing the flow rates under different heat release modes, it was found that at a discharge flow rate of 100-175 L/h, the heat release ratio of the phase change materials was maintained above 88%. The hot water supply volume reached 135 L. However, the heat transfer between the fluid and the phase change materials was no longer timely when the flow rate increased. The heat release ratio of the phase change materials gradually decreased to 81.5%, and the hot-water supply volume decreased to 125 L. To improve the heat discharge performance of phase change materials in a heat-storage water tank, it is necessary to ensure sufficient external heat transfer conditions and fundamentally improve the heat exchange capacity of the phase change materials.

A household photovoltaic intelligent power supply system was proposed to increase the on-site consumption capacity of household photovoltaics and fulfill the requirements for a comfortable and convenient living environment. The system can fulfill the requirements of household electricity, space heating, space cooling, and hot water supply throughout the year. Heating and cooling were realized using air source heat pumps (ASHP), underfloor heating, fan coil units, and energy storage water tanks, which store hot water in winter and cold water in summer. A TRNSYS simulation model of the system was created based on residential buildings in Shandong, China. Based on the simulation results and local electricity prices, the energy storage operation plan was optimized, and the economic efficiency of the system was analyzed. The results indicate that the system can meet the building's year-round electricity consumption, maintain indoor temperatures in winter and summer, and generate revenue from photovoltaic power, yielding the maximum return on investment throughout the entire life cycle. The optimal operating schedule for the ASHP is from 09:00 to 16:00 and 22:00 to 05:00 in winter and from 07:00 to 18:00 and 22:00 to 05:00 in summer. Controllable electrical appliances were used from 10:00 to 16:00. In contrast, appliances with energy storage were used from 11:00 to 14:00 to consume and store the photovoltaic electricity. The energy-storage water tank reduces standard coal consumption by 46% compared to the case without a water tank, demonstrating a substantial energy-saving effect.

Hydrogen energy, as a carbon-free energy source and a pivotal technology for attaining the goals of "carbon peaking and carbon neutrality", has attracted considerable global interest in recent years. The storage of liquid hydrogen offers several advantages owing to its high hydrogen storage density, low storage pressure, and high energy density. However, the industrial development of hydrogen energy still faces many problems. Technologies for large-scale, long-term storage and long-distance transportation are crucial problems in the utilization of liquid hydrogen. Therefore, it is necessary to develop efficient technologies for storing and transporting liquid hydrogen and to build large liquid hydrogen storage tanks with good thermal insulation performance. In this paper, the development status of large liquid hydrogen storage tank storage technology at home and abroad is reviewed, and key problems such as cryogenic insulation and material thermal stress in liquid hydrogen storage are analyzed. The difficulties associated with hydrogen storage and transportation are highlighted, and the development direction of liquid hydrogen storage technology is examined.

An electric vertical take-off and landing flying vehicle (eVTOL) is a potential technology for future urban air mobility. A major challenge for thermal management systems is the high cooling requirement and the variable application scenarios. To overcome this challenge, a multi-scene eVTOL-integrated thermal management system was developed. In this study, an eVTOL thermal management simulation platform based on Amesim simulation software was developed to investigate the effects of flight conditions on thermal management and range. The simulation results show that increasing the cruise altitude can reduce the thermal management energy consumption when the ground temperature is high. The maximum reduction of energy consumption for thermal management energy is 4 kW when the cruising temperature ranges from 10 ℃ to 26 ℃. When the hovering rescue duration is more than 150 s during the emergency rescue operation, the temperature difference inside the battery becomes too pronounced. A reduced payload improves the range, with the unloaded range being 1.33 times greater than the fully loaded range.

A transcritical CO₂ heat-pump air-conditioning system has effective heating performance at low temperatures, and the variation of dynamic parameters during operation significantly affects the thermal comfort inside the passenger cabin. To study the comfort of the passenger compartment and the coupling law of the dynamic changes in the parameters of the transcritical CO₂ heat-pump air-conditioning system, a joint simulation model was built based on the one-dimensional simulation software GT-Suite and the three-dimensional computational fluid dynamics (CFD) software STAR-CCM+. The three-dimensional cabin model can provide accurate real-time state parameters of the supply and return air for a one-dimensional simulation system of heat-pump air conditioners. The results show that the temperature distribution of the thermal environment of the passenger compartment is relatively non-uniform, necessitating the application of the weighted predicted mean vote (PMV) to evaluate this non-uniformity. In a multi-PID control transcritical CO₂ automobile heat pump air conditioning system, a control method based on the weighted PMV comfort model can maintain the regulation and stability of the system's target parameters. Under ambient temperature conditions of 43 ℃ in cooling mode, the control method can reduce the compressor's power consumption by 9.4%. At an ambient temperature of -10 ℃ in heating mode, this method can reduce compressor's the power consumption by 17.9%. This control method can reduce the power consumption of the system compressor while satisfying comfort requirements, constituting a highly efficient energy-saving strategy.

As the power density of lithium-ion batteries continues to increase and high-power fast-charging technologies emerge, the development of battery thermal management systems has become an important and challenging area of research. In this study, a direct-cooling thermal management system for multi-box battery packs using roll-bond cold plates was presented, and the performance of the system was experimentally investigated under different operating conditions. The experimental results show that at a charging rate of 0.5 C and a compressor speed of 2 400 r/min, the average coefficient of performance (COP) of the system can reach 5.83, the maximum dimensionless loss coefficient of the cold plate is 6.27%, and the maximum temperature difference between the cold plates is 1.90 ℃. Notably, the temperature difference between the plates escalates with increasing compressor speed and the thermal load on the cold plate, reaching a maximum value of 3.99 ℃ during the tests. Concurrently, the COP of the system showed a decreasing trend with the compressor speed, reaching a maximum value of 7.41 throughout the duration of the experiments.

In this study, the critical snow formation height of a mixed single-aperture nucleator in an artificial snow machine was examined. The threshold values of critical snow formation height were experimentally measured at different air-water pressure ratios and ambient temperatures, and the effects of air-water pressure ratios and ambient temperatures on the threshold values of critical snow formation heights were analyzed. The results showed that the threshold value for the critical height of critical snow formation did not exist at temperatures of -5 ℃ and -10 ℃ under the working conditions with a gas-water pressure ratio of 0.40 MPa∶0.40 MPa, but snow formation could be realized at -15 ℃, and the threshold value for the critical height of critical snow formation was 50-55 cm. When the gas-water pressure ratio is 0.50 MPa∶0.45 MPa or 0.50 MPa∶0.40 MPa, snow can be formed at ambient temperatures of -5 ℃, -10 ℃, and -15 ℃. The gas-water pressure ratio and ambient temperatures have a certain influence on the height of critical snow formation. Under the same ambient temperature, the greater the gas-water pressure ratio, the lower the critical snow height. Provided that the gas-water pressure ratio remains constant, the critical snow height decreases when the ambient temperature lowers from -5 ℃ to -15 ℃, and the trend of the change is more obvious in the temperature interval from -5 ℃ to -10 ℃.

Nucleator nozzles play an important role in promoting the rapid nucleation, crystallization, and snow formation of artificial snow droplets. A visual experimental platform was designed to investigate the gas-liquid two-phase flow process inside the nucleator nozzle and its influence on atomization behavior. The results showed the presence of a two-phase annular flow within the nucleator nozzle and a continuous hollow-cone spray field outside the nucleator nozzle. As the gas-liquid pressure ratio (Φ_GL) increases, the interfacial disturbance waves at the gas-liquid interface of the internal flow gradually disappear. As the air core occupied more space, the liquid film thickness gradually decreased and became uniform and stable. This markedly improved the atomization efficiency and quality. When the Φ_GL was increased from 20% to 67%, the uniformity and stability of droplet distribution increased by 17% and 60%, respectively. This research offers important guidance for the structural design of high-performance atomized components.

As the driving component of a valved linear compressor, the matching relationship between the motor force and gas force directly affects the performance of the compressor. A simulation model of the linear motor was established based on the equivalent gas-force model. In addition, a test bench for the valved linear compressor was constructed to analyze both the simulation and experimental results under various working conditions. This study aimed to investigate the performance of a compressor across different operating scenarios while verifying the reliability of gas force linearization. When the inflation pressure and piston pressure were 0.2 MPa and 5 mm, respectively, the resonance frequency of the experiment and simulation was 50 Hz, and the motor efficiency was 84.3%. The maximum relative errors of the input work, voltage, current, and motor efficiency were 25.8%, 21.7%, 22.7%, and 13.5%, respectively. This indicates that the motor efficiency of the compressor is related to its resonance frequency and that the motor efficiency of the compressor is the highest when the resonance frequency is consistent with the operating frequency. The simulation model of the linear motor is reliable, and the calculation results for the gas load are relatively accurate.