As one of the most promising thermal management solutions, spray cooling has the advantages of high heat-transfer coefficient and maintaining a low temperature of the cooling surface. By summarizing the influential factors and practical applications of spray cooling, the current challenges and bottlenecks were indicated so as to prompt its potential applications in the future. Firstly, this paper reviewed the heat-transfer mechanism of spray cooling and found that spray cooling is more advantageous for heat dissipation in high-power electronic devices by comparing it with other cooling techniques. Secondly, the latest experimental studies on spray cooling were reviewed in detail, especially the effects of spray parameters, types of working fluid, surface modification, and environmental parameters on the performance of cooling system. Afterwards, the configuration and design of the spray cooling system, as well as its applications in the actual industry (data centers, hybrid electric vehicles, and so on) were enumerated and summarized. Finally, the scientific challenges and technical bottlenecks encountered in the theoretical research and industrial application of spray cooling technology were discussed, and the direction of future efforts were reasonably speculated.

In this study, three-dimensional thermal simulations for a 54 V Lithium-ion battery pack composed of 18 LiFePO₄ pouch battery cells connected in series were conducted using a multi-scale electrochemical-thermal-fluid model. An equivalent circuit model (ECM) is used as a subscale electrochemical model at each cell node of the battery, which is then combined with the macro-scale thermal and fluid equations to construct a model of the battery and battery pack. With the model, the cooling effects of indirect cooling and direct cooling battery thermal management systems (BTMS) on the battery pack under rapid discharging conditions are explored. It is found that when the battery pack is discharged at 2C, indirect cooling of the bottom plate can effectively dissipate heat and control the temperature of the battery pack. Under the 10C discharging condition, the maximum temperature of the battery pack will exceed 100 °C, and the temperature uniformity will be very poor when using indirect cooling of the bottom plate for the battery pack. Direct air cooling is also unable to meet the cooling requirements of the battery pack at a 10C discharging rate. The possible reason is that the convective heat transfer coefficient of direct air cooling is small, which makes it difficult to meet the heat dissipation requirements at the 10C condition. When single-phase direct cooling with fluorinated liquid is used, the maximum temperature of the battery pack under the 10C discharging condition can be controlled at about 65 °C. Compared with air direct cooling, the pressure drop of fluorinated liquid single-phase direct cooling is smaller, and the obtained battery pack temperature uniformity is better. From the detailed study of fluorinated liquid single-phase direct cooling, it is concluded that increasing the coolant flow rate and reducing the cell spacing in the battery pack can achieve a better cooling effect. Finally, a new cooling method, two-phase immersion cooling, is investigated for cooling the battery pack. The maximum temperature of the battery pack discharged at a 10C rate can be controlled below 35 °C, and good temperature uniformity of the battery pack is also achieved at the same time. This study focuses on fluorinated liquid immersion cooling using numerical simulations, showing that it is a promising cooling method for lithium-ion battery packs and deserves further study. This paper will provide a reference for the design and selection of BTMS for electric vehicles.

We do not fully grasp viral droplet transmission processes in ventilated interior environments. The core focus of our research is to investigate the effectiveness of the protected occupied zone ventilation (POV) through computational fluid dynamics models in a simplified office setting. The large-eddy simulation technique with the Eulerian–Lagrangian model was implemented to address complicated indoor processes such as turbulence, flow–aerosol interaction, and ventilation impact. We computationally investigated the effects of desk partitions and the POV on cough droplets in an office. The ventilation approach was tested using two distinct exhaust layouts and four different ventilation rates (1.0, 1.2, 1.5, and 1.8 m/s). A comparative analysis of the ventilation flow fields, topologies, and particle directions has been studied. The findings indicate that the plane jet's ventilation rates influence the protected occupied zone ventilation performance. The ventilation rates distributed the virus droplets around the room, but compared to the up-exhaust cases, the down-exhaust cases appeared to have better shielded the healthy person. This pattern could indicate that the placement of the exhaust outlet in ventilation systems significantly influences indoor aerosol dispersion. The results also show that substantial flow streams may carry tiny particles (≤70 μm) throughout their path. Large particles (≥100 μm) could not go far in cough gas clouds. Most viral particles deposit on solid surfaces in various work sites per specific ventilation rates. Office workers need to be very cautious around these hazardous areas.