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.

With the development of cold chain Internet of Things (IoT) technology, real-time temperature monitoring and data sharing have become important means to improve the efficiency of chilled meat supply chain management. In this paper, a strategy for optimizing time and temperature coordination based on the cold chain IoT was proposed to improve the operational efficiency of the chilled meat supply chain. Based on predictive microbiology and system reliability theory, this study investigated the effects of time and temperature on the quality of chilled meat. A quality-change model for chilled meat and an energy consumption model for the chilled meat supply chain were developed. To illustrate this approach, a case study of a chilled chicken supply chain was conducted. The findings revealed that there is an optimal level of freshness in the chilled meat supply chain that maximizes the benefits of the supply chain. If the freshness level in one stage deviates from this optimal value, subsequent stages can adjust the time and temperature to achieve maximum supply chain efficiency.

To investigate the effect of different drying conditions on the efficacy of a closed heat pump clothing-drying system, parametric studies with control variables were carried out on the circulating air volumetric flow rate, expansion valve opening, and air inlet temperature within the drying chamber and their impact on system heat production, heat pump system coefficient of performance (S_COP), cooling capacity utilization ratio (E_R), and exergy loss. The findings indicated that when the expansion valve was set to 70% opening, the circulating air volumetric flow rate was increased from 500 m³/h to 1 000 m³/h, and the heat generation of the system increased by 59.73%. In contrast, the S_COP, E_R, and exergy loss decreased by 31.29%, 56.65%, and 31.31%, respectively. Furthermore, when the circulating air volumetric flow rate of 1 000 m³/h was maintained while adjusting the expansion valve opening from 20% to 70%, the heat generation, S_COP, and E_R of the system increased by 32.58%, 6.51%, and 29.51%, respectively. At the same time, the exergy loss decreased by 12.44%. Finally, under the conditions of a 70% open expansion valve, a circulating air volumetric flow rate of 1 000 m³/h, and an increase in the desiccator′s air intake temperature from 40 ℃ to 70 ℃, the heat generation of the system increased by 43.71%, while the S_COP, E_R, and exergy loss decreased by 11.22%, 60.84%, and 14.17%, respectively. These results emphasize the advantages of reducing the circulating air volumetric flow rate and inlet air temperature within the drying chamber while increasing the expansion valve opening, as these adjustments help to improve the overall performance of the system and promote energy efficiency.

An experimental platform was built to evaluate the thermal switching performance of a parallel pulsating multi-channel heat pipe using fluoroether HFE-7100 as the working fluid with a liquid filling ratio of 80%. The heating and cooling temperatures of the pulsating heat pipe were controlled using water baths for heating and cooling. The thermal switching characteristics of the pulsating heat pipe at different cooling temperatures were investigated experimentally. The results showed that after the complete start-up of the multi-channel parallel pulsating heat pipe, the average temperature of the evaporation section decreased, the average temperature of the condensation section increased, the thermal resistance decreased, and the heat transfer performance improved rapidly. The temperature and thermal resistance transient processes exhibited a sudden step change, which can be used as a thermal switch. As the cooling temperature increased, the closing time of the thermal switch and the switch temperature increased. At a cooling temperature of 10 ℃, the closing time of the thermal switch was 12 s, and the switch temperature was 59.3 ℃. At higher cooling temperatures, the thermal switch performed better, characterized by a greater increase in the switch ratio and heat transfer rate. When the cooling temperature was 30 ℃, the heat transfer rate increased by 26.8 W following the closure of the thermal switch, with a switch ratio of 5.05.

This study utilizes machine learning techniques to conduct an in-depth analysis of time-series historical data on energy consumption in buildings. A generalized model identification method was developed using an optimization algorithm based on black-box models. The final identification model was determined after optimizing three machine learning methods, including polynomial regression, artificial neural networks, and extreme gradient boosting. A near-zero energy office building in Beijing is the primary focus of this study. Using historical building data and simulation data of the heating system in TRNSYS, load prediction and equipment energy consumption models were established using the developed model identification method. During deployment, the predicted R² value and total energy consumption deviation were 0.87 and 5.18%, respectively. The results demonstrate that the prediction models established through this method possess high accuracy, providing a reliable basis for subsequent system energy consumption optimization.

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.

Dimethyl sulfoxide (Me₂SO) in cell banking exhibits significant side effects on both the cells and the human body. Therefore, an approach that mitigates the side effects of Me₂SO with comparable efficacy is urgently needed. The human umbilical cord mesenchymal was used as the research material. First, the thermal physical properties of trehalose, glucose, and L-proline and their regulation of ice crystal growth were measured using a differential scanning calorimeter and a cryomicroscope. Cryopreservation experiments were performed to determine the optimal concentration of each component in the cryopreservation solution, and the viability and functionality of the cells after cryopreservation were validated. The results show that there is no significant difference in cell viability (92.42%±0.28%) and recovery rate (87.80%±4.22%) between the use of the novel stem cell cryopreservation solution (1.25 mol/L ethylene glycol+10 g/L whey protein+0.1 mol/L trehalose+Normosol-R) and the conventional cryopreservation solution (a volume fraction of 10% Me₂SO). Moreover, after 3 days of culture, the cell number was (12.42±0.60) × 10⁶ (proliferation fold of 4.97), and the cell phenotype was not significantly different from that of fresh cells. The proposed novel solution for stem cell cryopreservation solves the problem of "Me₂SO-free" cryopreservation of cells and offers promising potential for clinical applications.

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.

The rapid development of microelectronic devices has driven a trend toward miniaturized and lightweight electronic devices with high heat flux. Porous structures are increasingly used in heat dissipation due to their ability to expand the heat transfer area, enhance nucleation sites for boiling, and regulate surface wettability, significantly improving boiling heat transfer. Microchannel heat dissipation technology based on porous structures has emerged as an effective and promising method to enhance heat sink performance. Recent advancements highlight three common configurations: porous structures on microchannel surfaces, porous materials within microchannels, and porous microchannel skeletons. These structures encompass coatings, microcavities, metal foams, porous fins, and ribs. This article reviews progress in microchannel heat dissipation using porous structures, evaluates the benefits and drawbacks of these configurations, addresses challenges such as balancing heat transfer and pressure drop, and proposes optimization strategies to overcome these issues.

Transcritical CO₂ heat pump air-conditioning systems have gained prominence in new energy vehicle thermal management due to their energy-saving and environmentally friendly characteristics. However, the relatively low coefficient of performance (COP) in cooling mode remains a significant obstacle to developing transcritical CO₂ heat pump air conditioning systems. To enhance system performance, five technical approaches are proposed: internal heat exchangers (IHX), expanders, vortex tubes, ejectors, and combined multiple evaporation steps with vapor injection. The performances of these methods were evaluated through one-dimensional theoretical calculations under vehicle operating conditions. Results indicate that optimizing discharge pressure is critical for all methods, with varying degrees of COP improvement. Expanders provide the most comprehensive benefits, ejectors perform well under specific design conditions, IHX shows notable enhancements in cooling mode, and vortex tubes and combined multiple evaporation steps with vapor injection exhibit broad adaptability across working conditions. These findings offer valuable insights for practical engineering applications and support the adoption of transcritical CO₂ heat pump systems in new energy vehicles.