Thermophysical properties of a phase change dispersion for cooling around 50 °c
Thermophysical properties of a phase change dispersion for cooling around 50 °c
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DOI：
10.1016/j.ijrefrig.2020.05.013
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发表时间：
2020-11-01
影响因子：
3.9
通讯作者：
Ding, Yulong
中科院分区：
文献类型：
--
作者：
Fischer, Ludger;Mura, Ernesto;Ding, Yulong
相变分散体最近在等温冷却应用中获得了兴趣。迄今为止，几乎所有研究的相变分散体都由石蜡作为相变材料组成。本文介绍了一种以两种脂肪酸酯为相变材料的相变分散液Crodatherm-53/Crodatherm-47（50：50）。该分散体具有50摄氏度的熔化温度，并且预见到在高压直流部件冷却中。用乳化剂稳定相变分散体以防止相分离，并加入成核剂以抑制过冷。从热历史计算，过冷度的分散体减少了10 K的添加成核剂。实现了单峰粒度分布。分散体在20重量%下的粘度100 μ s（-1）的剪切速率在25 ℃时为4.9 mPa·s，在60 ℃时为2.0 mPa·s。并对不同温度、质量分数和剪切速率下的粘度进行了评价。从DSC分析，测得相变分散体的表观比热容为8.5 kJ kg（-1）K-1。该值是水在所需熔化范围（47.5-50.0摄氏度）内的表观比热容的两倍。热导率测量表明，在25 ℃下，乳液形式的相变分散体的热导率为0.529 W m（-1）K-1，在60 ℃下，悬浮液形式的热导率为0.561 W m（-1）K-1。在每个温度下，这两个热导率值都低于水。(C)2020作者出版社：Elsevier Ltd
Phase change dispersions have recently gained interest in isothermal cooling applications. So far, almost all of the investigated phase change dispersions consist of paraffins as the phase change materials. This paper presents a phase change dispersion with two fatty-acid esters as the phase change material, Crodatherm-53/Crodatherm-47 (50:50). The dispersion has a melting temperature of 50 degrees C and is foreseen in high-voltage direct current component cooling. The phase change dispersion was stabilised with emulsifiers to prevent phase separation and nucleation agents were added to supress supercooling. From thermal history calculations, the supercooling of the dispersion was reduced by 10 K with the addition of the nucleation agent. A monomodal particle size distribution was achieved. The viscosity of the dispersion at 20 wt.% and shear rate of 100 1 s(-1) was found to be 4.9 mPa.s at 25 degrees C, and 2.0 mPa.s at 60 degrees C. The viscosity at different temperatures, mass fractions and shear rates was also assessed. From DSC analysis, an apparent specific heat capacity of 8.5 kJ kg(-1) K-1 was measured for the phase change dispersion. This value is double the apparent specific heat capacity of water within the desired melting range (47.5-50.0 degrees C). Thermal conductivity measurements showed in the emulsion form, at 25 degrees C the phase change dispersion had a thermal conductivity of 0.529 W m(-1) K-1 and in suspension form at 60 degrees C was 0.561 W m(-1) K-1. Both thermal conductivity values were lower than water at each temperature. (C) 2020 The Authors. Published by Elsevier Ltd.