Integrated Model of a Walking Human and a Hygroscopic Porous Clothing System
The objective of this work to develop a 1-D transient heat and mass transfer model of a walking clothed human
to predict the thermal response and the dynamic clothing dry heat and insulation values and vapor resistances.
Developing an integrated model of human and clothing system under periodic ventilation requires estimation of
the heat and mass transfer film coefficients at the skin to the air layer separating the skin and the fabric for
normal air flow at different ventilation frequencies. Experiments were conducted in an environmental chamber
under controlled conditions of 25°C and 50% relative humidity to measure the mass transfer coefficient at the
skin to the confined air layer separating the wet skin and the fabric. A 1-D mathematical model is then developed
of the clothed walking human using Gagge's two-node model to simulate the human physiological regulatory
responses. The human model is coupled to the clothing three-node model of Ghali et al. (2001) of the fabric that
takes into consideration the effect of fabric periodic ventilation. The developed dynamic model is used, at a fixed metabolic rate of the human body, to predict the periodic ventilation flow rate in and out of the fabric, the periodic fabric regain, the fabric temperature, and the values of heat loss or gain from the skin. The heat loss from the skin increases with the increase of the frequency of ventilation that is proportional to the activity level of the human. In addition, the evaporative and dry resistances of the clothing fabrics predicted by the current model compared well with published experimental data and show significant decrease in the clothing dry insulation.