石蜡相变乳液的热稳定性及换热性能研究

Study on thermal stability and heat transfer properties of paraffin phase change emulsions

以相变峰为55℃的石蜡为相变材料,聚氧乙烯硬脂酸酯S100和聚氧乙烯硬脂酸酯S2为乳化剂,制备了一种可用于流动换热的石蜡相变乳液。最佳工艺条件下[石蜡/乳化剂质量比为20/1,超声时间5min,亲水亲油平衡值(HLB)值为12]制备的石蜡相变乳液经过480次冷热循环后仍保持良好的循环热稳定性,过冷度低,最大比热容为9.136J/(g·K),在相变峰值点(55℃)黏度为2.17mPa·s。换热效率计算表明,石蜡相变乳液的最低理论泵功率比为0.33,比水具有更高的换热效率,可用作太阳能集热供热管理系统的流动换热工质。

Paraffin wax with a melting point(T_(m))of 55℃ was used as the phase change material,and Steareth-100 and Steareth-2 were used as emulsifiers to prepare a paraffin phase change emulsion that could be used for flow heat transfer.Under the optimal process conditions(paraffin/emulsifier ratio of 20/1,ultrasonic time of 5min,and HLB value of 12),the prepared paraffin phase change emulsion remained excellent cyclic thermal stability after 480 heating and cooling cycles,with a low subcooling degree and a maximum specific heat capacity of 9.136J/(g·K).Moreover,it had a low viscosity of 2.17mPa·s at the temperature of 55℃.Finally,the evaluation of heat-transfer efficiency presented that the paraffin phase change emulsion had a higher efficiency than water,and the lowest theoretical pump power ratio P_(PCME)/P_(Water) was 0.33,making it suitable as a heat transfer fluid for solar thermal management systems.