板状相变蓄冷单元快速释冷特性实验研究

Experimental Study of Quick Cold-release Characteristic of Plate-shaped Phase Change Cold-storage Units

间歇工作高通量发热设备的紧凑高效冷却系统中需用到快速相变蓄冷单元。以膨胀石墨基定型相变材料为主要原料制备了板状相变蓄冷单元,在自建实验台上通过改变取冷流体的进口温度和流量对其快速释冷特性进行实验研究。结果表明:在释冷过程中,瞬时释冷强度q持续减小,先快后慢;累积释冷量Q持续增大,亦先快后慢;综合传热系数K则先快速减小,继而平缓波动;取冷流体流量仅对K有明显影响,进口温度对K、q和Q均有明显影响。在8种实验工况下,潜热释冷阶段K的平均值在279～402W/(m^2·K)范围内,10min内q的平均值为2.67～3.82kW,Q可达2 300kJ以上,基本满足特定情况下的使用要求。下一步应优化板状快速相变蓄放冷单元表面的传热纹理结构,进一步改善释冷特性。

Rapid phase change cold-storage units are needed in compact and efficient cooling systems of the high-throughput heating equipment for intermittent work. Plate-shaped phase change cold-storage units are prepared with the expanded graphite stable phase change materials as the main component. Their quick cold-release characteristics are studied by changing the inlet temperature and flow rate of cooling fluid on homemade experimental platform. Results show:① during the cold-release process, the instantaneous cold release intensity ( q ) continuously decreases, rapidly first and then slowly with time, and the accumulative cooling capacity ( Q ) continuously increases rapidly first and then slowly, while the comprehensive heat transfer coefficient ( K ) at first falls quickly followed by gentle undulation;② the inlet flow of fluid only affects K , while the inlet temperature of fluid obviously influences all of the above parameters;③ under the eight experimental conditions, the mean K falls within the range of 279~402 W/(m^2·K) during the latent heat release stage, the mean q within the range of 2.67~3.82 kW during the first 10 minutes, Q respectively attains above 2 300 kJ. In general, the plate-shaped phase change cold-storage units basically meet the use requirement under certain circumstances. To further improve the cold-release characteristics, the surface heat transfer texture of plate-shaped phase change cold-storage units needs to be designed and optimized.