Dispersion stability and thermophysical properties of microencapsulated phase change material slurry for liquid desiccant dehumidification

Abstract

The dispersion stability and the thermophysical properties of the microencapsulated phase change material slurry (MPCMS) for liquid desiccant dehumidification were investigated experimentally. The results show that, the dispersion stability of the MPCMS can be improved greatly by adding surfactant. The maximum absorbency of MPCMS with polyoxyethylene sorbitan monooleate (Tween80) is 4.1 times that of MPCMS with cetyltrimethyl ammonium bromide (CTAB). The monolayer adsorption model is suitable for predicting the optimal mass content of surfactant with the maximum relative error of 13.3%. The thermal conductivity of MPCMS is lower than that of the base fluid and decreases with the increasing MicroPCMs concentration, when the mass fraction of MicroPCMs increases from 0% to 2.0% at the temperature of 20 °C and 40 °C, the thermal conductivity decreases by 25% and 14.8%, respectively. When the mass concentration of MicroPCMs is lower than 1.0%, the thermal conductivity of MPCMS keeps increase with the temperature rise. While the mass concentration of MicroPCMs ranges from 1.0% to 2.0%, the thermal conductivity of MPCMS increases firstly and then declines gradually. Moreover, an improved interfacial layer based thermal conductivity calculation correlation was proposed, in which the influence of temperature and concentration of MPCMS were considered, the maximum deviation and mean deviation between the calculated value and the experimental one are 5.62% and 1.85%, respectively. In the range of phase transformation temperature, the specific heat capacity of the slurry can be significantly improved by the MicroPCMs, the maximum specific heat capacity of the MPCMS reaches 2.3 times that of the pure lithium chloride aqueous solution. In addition, the effect of the mass concentration of MicroPCMs on the specific heat capacity is much greater than that of the temperature and the mass concentration of LiCl. The findings provide experimental foundation and guidance for the practical application of MPCMS in liquid desiccant dehumidification.