Ovarian tissue cryopreservation is an important method for female fertility preservation. Slow freezing of ovarian tissue results in poor follicular survival and low retransplantation efficiency. This study optimized the ovarian tissue cooling procedure by ice seeding, and the effects of ice seeding temperature and cooling rate after seeding on ovarian tissue cryopreservation were analyzed. The programmed cooling apparatus was combined with an ultrasonic device to achieve the ultrasonic seeding of ice crystals, and the ultrasonic intensity was screened. The ovarian survival and histology were assessed after rewarming. The results revealed that the optimized cooling procedure with ice seeding reduced the damage to ovarian tissues. When ice seeding was triggered at -11 ℃ with a cooling rate of 1 ℃/min after nucleation, follicle survival was 88.02%. Ultrasonic nucleation equipment enabled contactless ice seeding of the samples, reducing the risk of contamination and improving the success rate of ice seeding. Furthermore, the follicle survival rate of frozen ovarian tissue increased to 88.38%. The optimization of the procedure and the improvement of the equipment improved the effect of ovarian tissue cryopreservation, reduced the risk of introducing contamination during the cryopreservation process, and provided a new method for the slow cryopreservation of ovarian tissues in clinics.

Improving the energy efficiency of data centers by conserving energy in cooling systems is a priority strategy. In this study, thermal analysis of the prevailing air-water-air cooling system revealed inefficiencies caused by a significant discrepancy in the flow rate between the air and water sides of the server room air conditioning system. To mitigate such discrepancy, a new system architecture with a high-temperature differential on the waterside was proposed. Compared with a conventional system with a small temperature differential, the proposed high-temperature differential cooling system substantially augmented the proportion of natural cooling throughout the year, reduced the energy consumption of pumping fluids, and reduced the total energy consumption of the cooling system by approximately 20%-30%. Although the introduction of a high-temperature differential cooling system requires an increase in the heat exchange area and an increase in the cost of air conditioning for the server room, it concurrently reduces the investment in cooling towers, chillers, circulating pumps, chilled water storage tanks, pipelines, and valves, ultimately reducing the total investment in the cooling system by 15%-25%. Furthermore, the high-temperature differential cooling system facilitates operational adjustments, decouples control from external temperature variations and IT load changes, and minimizes maintenance requirements.

Topological fins can significantly improve heat transfer in latent heat storage units. In this study, a two-dimensional topology optimization model for a shell-and-tube latent heat storage unit was developed and experimentally validated. The optimal fin for different operating conditions and charge-discharge cycles was investigated. Box-counting dimensions and fin surface areas per unit length were used to characterize the topological fins. The results showed that increasing the charging time simplified the fin structures, whereas discharging times of more than 600 s extended the fin tips. For the 3 000 s charge-discharge cycle, the optimal fin increased the surface area per unit length by 80% and the discharge energy density by 37.6% compared to the fin for the 3 000 s charging process. The topological fin for a 300 s discharge-charge cycle with an extended branch resulted in a 7.7% increase in heat storage density.

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.

Energy storage technology can balance the mismatch between energy supply and demand, which is an important link between the use of renewable energy and waste heat. Absorption thermal energy storage has attracted considerable attention in recent years owing to its high energy-storage density, high energy-storage efficiency, low charging temperature, low heat loss, and flexible output. A state-of-the-art review of advanced cycles, working pairs, and experimental prototypes was conducted. The development of advanced cycles has further improved the energy storage density and efficiency and lowered the charging temperature. The screening of novel working pairs solved the crystallization problem of conventional salt solutions, increased the options of working fluids for different scenarios, and reduced costs. The successful development and operation of experimental prototypes have confirmed the excellent performance of absorption thermal energy storage and paved the way for its promotion and application. In conclusion, the challenges and opportunities of absorption thermal energy storage for the future are summarized, and the development direction is discussed.

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.

Displacer-type pulse-tube cryocoolers use a displacer for phase adjustment and recovery of acoustic power, leading to high refrigeration efficiency. Despite their potential, there is limited research on highly efficient displacer-type pulse-tube cryocoolers with large cooling capacities near -100 ℃. This paper presents the design of a 100-watt displacer-type pulse-tube cryocooler for low-temperature freezers and evaluates its performance, focusing on displacement motion and compressor efficiency. A validated numerical model was employed to analyze the coupling between the pulse tube and compressor and the internal phase relationship of the cold finger. Results show that under operating conditions of a 3.0 MPa charging pressure, 64.9 Hz frequency, 20 ℃ cooling water temperature, and 500 W input power, the cryocooler achieved a cooling capacity of 160.3 W at -100 ℃ with a relative Carnot efficiency of 22.2%. The displacer led the compressor piston by 59°, the internal phase distribution of the pulse tube was optimal, and the compressor exhibited a high efficiency of 78%. This cryocooler is the most efficient displacer-type pulse-tube cryocooler in its temperature range.

Battery thermal management systems are crucial components of pure electric vehicles. The promising application of liquid immersion technology in electronic equipment has also garnered increasing attention for its potential in battery thermal management. Power battery immersion liquid-cooling technology involves directly immersing the battery in dielectric liquid to dissipate heat through convection or phase-change heat transfer. This study analyzes the impact of temperature on battery performance and compares the advantages and limitations of different thermal management systems. The importance of immersion-based battery thermal management is emphasized. Key technical challenges and recent research advancements are reviewed in detail, including coolant selection, module design, and considerations for battery life and safety. Finally, commercially developed immersion cooling products for demonstration and exploration are introduced.

Superhydrophobic surfaces, a new type of green material, exhibit promising application prospects in the field of anti-/de-icing. In this paper, the kinetic behavior of impinging droplets on surfaces with different temperatures (-25-16 ℃), different inclination angles (0°-60°), and different wettability (hydrophilic and superhydrophobic surfaces) is investigated through experimental comparisons. The variations of the droplet morphology, spreading factor, spreading time, and contact time are analyzed. The results show that the impinging droplets exhibit different kinetic behaviors after spreading due to the different inclination angles and wettability. The maximum spreading factor and spreading time on hydrophilic surfaces increase with the inclination angle. The variation of the spreading time on superhydrophobic surfaces follows the same trend as that on hydrophilic surfaces, while the maximum spreading factor decreases with an increase in the inclination angle, especially at T_s-25 ℃; Compared to hydrophilic surfaces, the impinging droplets have shorter spreading times on superhydrophobic surfaces, which can reach about 10 times at T_s=-25 ℃. Increasing the wall inclination angle breaks the symmetric bounce of the droplets on the horizontal superhydrophobic surface, thereby shortening the contact time of the droplets. This suggests that increasing the inclination angle can effectively inhibit the freezing of water droplets.