Thermophysical properties of a phase change dispersion for cooling around 50 °c

• Published in: International journal of refrigeration Vol. 119; pp. 410 - 419
• Main Authors: Fischer, Ludger, Mura, Ernesto, O'Neill, Poppy, von Arx, Silvan, Worlitschek, Jörg, Qiao, Geng, Li, Qi, Ding, Yulong
• Format: Journal Article
• Language: English
• Published: Paris Elsevier Ltd 01.11.2020; Elsevier Science Ltd
• Subjects: Cooling; Direct current; Dispersion; Dispersion à changement de phase (PCD); Dispersions; Emulsifiers; Esters; Heat conductivity; Heat transfer; Matériau à changement de phase (PCM); Melt temperature; Melting; Nucleation; Paraffins; Particle size; Particle size distribution; Phase change dispersion (PCD); Phase change material (PCM); Phase change materials; Phase separation; Phase transitions; Propriétés thermophysiques; Reagents; Shear rate; Specific heat; Supercooling; Temperature; Thermal conductivity; Thermophysical properties; Transfert de chaleur; Viscosity; Phase change material (PCM); Transfert de chaleur; Matériau à changement de phase (PCM); Thermophysical properties; Phase change dispersion (PCD); Heat transfer; Dispersion à changement de phase (PCD); Propriétés thermophysiques
• ISSN: 0140-7007; 1879-2081
• DOI: 10.1016/j.ijrefrig.2020.05.013

•Properties of a phase change dispersion are experimentally determined•Phase change material in the dispersion was two fatty acid esters•Supercooling was reduced by 10 K using nucleating agents•Apparent specific heat of 8.5 kJ kg−1 K−1 over the temperature range 47.5–50.0 °C. 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 °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 1s−1 was found to be 4.9 mPa۰s at 25 °C, and 2.0 mPa۰s at 60 °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 °C). Thermal conductivity measurements showed in the emulsion form, at 25 °C the phase change dispersion had a thermal conductivity of 0.529 W m−1 K−1 and in suspension form at 60 °C was 0.561 W m−1 K−1. Both thermal conductivity values were lower than water at each temperature.