Analysis of the Properties and Thermal Behavior of Low-Temperature Phase Change Materials (PCMs) That Can Be Applied in Heating and Ventilation Systems.

Abstract

This article analyses the use of low-temperature PCMs in devices supplementing a room ventilation system to prevent the overcooling effect. In this study, the phase change is numerically simulated in an axisymmetric system consisting of two tubes. One is filled with RT11HC with an initial temperature of 0 °C, while air with an inlet temperature of 20 °C flows through the other, heating the PCM and causing it to melt. Calculations are performed using commercial software with the apparent heat method for a system of given dimensions. Spatial distributions of the system temperature and liquid volume fraction at different time moments (from 0 to 120 min) are determined. It is found that the results depended mainly on the method of determining the latent heat. For the beginning of the charging process (<i>t</i> < 40 min), the values of the liquid phase fraction determined by the H and S methods are similar, while the one determined by the G method is definitely higher (even three times at <i>t</i> = 10 min). In turn, the outlet air temperature determined by the S method is lower than that determined by the other methods. The size and shape of the mesh have no significant effect on the results.