Xiaoqin Sun

Development and verification of an EnergyPlus-based algorithm to predict heat transfer through building walls integrated with phase change materials

A conduction finite difference algorithm developed for EnergyPlus was used to model building walls integrated with phase change materials. The model was validated by comparing it against experimental data in terms of temperatures, wall heat fluxes, and total wall heat transfer. Experimental data, using two identical test houses of conventional residential construction, were collected for the validation and further analyses. The thermal performance of walls without phase change materials (control house) and with phase change materials (retrofit house) was evaluated. The model showed that the differences between experimental and predicted total heat transfer values were under 5%. The total heat transfer reductions produced by phase change materials could be predicted accurately using the conduction finite difference algorithm in EnergyPlus.

Melting temperature and enthalpy variations of phase change materials (PCMs): a differential scanning calorimetry (DSC) analysis

ABSTRACT Differential scanning calorimetry (DSC) analysis is a standard thermal analysis technique used to determine the phase transition temperature, enthalpy, heat of fusion, specific heat and activation energy of phase change materials (PCMs). To determine the appropriate heating rate and sample mass, various DSC measurements were carried out using two kinds of PCMs, namely N-octadecane paraffin and calcium chloride hexahydrate. The variations in phase transition temperature, enthalpy, heat of fusion, specific heat and activation energy were observed within applicable heating rates and sample masses. It was found that the phase transition temperature range increased with increasing heating rate and sample mass; while the heat of fusion varied without any established pattern. The specific heat decreased with the increase of heating rate and sample mass. For accuracy purpose, it is recommended that for PCMs with high thermal conductivity (e.g. hydrated salt) the focus will be on heating rate rather than sample mass.