相变蓄冷换热器的优化设计

Optimization of a Thermal Energy Storage Heat Exchanger

针对某间歇剧烈放热的设备,设计了一套某带相变蓄冷换热器的泵驱两相环路热控系统,并对相变蓄冷换热器进行优化设计。经过比较,拟采用石蜡与膨胀石墨的混合物为相变材料(PCM),在大大提高材料热导率时,又可保持较大的相变潜热。为了提高换热效率,应尽量避免PCM的融化距离过深,同时应优先减小外管壁与PCM间的接触热阻。相变蓄冷换热器的最优管间距与蓄冷时间、冷凝传热系数和接触表面传热系数等因素密切相关,本相变蓄冷器的最优管间距选为30 mm.通过动态模拟,可以得到相变蓄热换热器内不同时间的温度分布,确认所设计的相变蓄冷换热器可以满足要求,并为储液器的设计提供了相变蓄热换热器内不同时间的空泡率。

To solve the heat transfer problem of a machine with intermittent high heat flux,a pumped two-phase loop thermal control system with a thermal energy storage heat exchanger(TESHE) was designed and the TESHE was optimized.The phase change material for the TESHE was selected as paraffin C15-Cl6/expanded graphite composite,which has both the advantage of high thermal conductivity and large heat of fusion.To increase the heat transfer efficient,the melting distant should not be too large,and the contact thermal resistance between the outer wall and the PCM should be reduced first.The optimized tube spacing was function of the melting time,heat transfer coefficient,contact thermal resistance and so on,and the optimized tube spacing here was chosen as30 mm.The dynamic modelling results show the temperature distribution in the TESHE at different time to confirm that the TESHE can meet the requirement.The dynamic modelling results can also provide void fraction distribution in the TESHE at different time for the accumulator design.