Heat and Moisture Transfer Characteristics of Multilayer Walls

Abstract

A transient model coupled heat, air and moisture is developed and validated to investigate the heat and moisture transfer characteristics of the exterior walls. Relative humidity and temperature are chosen as the driving potentials. The temperature, relative humidity and heat flux of the internal surfaces of the Expanded Polystyrene( EPS) external insulation wall and concrete wall are analyzed. The results show that, when considering moisture transfer, the temperature fluctuations of internal surface is reduced. The thermal insulation wall has the lower internal surface temperature and is beneficial to improve the indoor thermal environment. The relative humidity of the inner surface of the insulation wall is higher. Moisture migration in the wall can cause moisture accumulation and the added latent heat caused by moisture transfer can’t be ignored. Heat flow through the inner surface of the insulation wall is smaller, therefore the insulation wall is helpful to reduce air conditioning load.