Improved thermal performance of face mask using phase change material

Abstract

The purpose of this work is to develop a mathematical model to study the thermal performance of a cloth face mask in which phase change material (PCM) is encapsulated as compared to a cloth mask alone. The thermal performance is assessed by the ability to reduce heat loss and water vapor transfer from the exhaled air to inhaled air as well as to reduce the potential for condensation in the mask fabric layers. The mathematical model incorporated all the complex transport mechanisms of heat and moisture, including the realistic breathing pattern for the air passing through the fabric. The core assumption of the model of non-local-thermo-equilibrium was validated by performing experiments on a common cotton cloth mask. The model predicted well the experimentally measured air temperature through a cotton cloth mask during sudden changes in thermal inflow conditions. The validated model was used to perform a parametric study to determine environmental conditions and PCM material characteristics for the enhanced performance of the cloth mask. It was found that a considerable increase in the reclaiming of sensible and latent energy was reached for the same ambient conditions by the introduction of PCM with melting temperature of 22℃ and PCM mass fraction of 20%. Furthermore, the incorporation of PCM allows inhalation of colder outdoor conditions with a high range of relative humidity without condensation at ambient temperatures lower than 12℃, which is not possible without PCM. For higher temperatures than 12℃, the introduction of PCM enlarged the possible range of relative humidity reached without condensation. © 2013, SAGE Publications. All rights reserved.