Simultaneous Heat, Moisture and Salt Transfer in Clothing

Sweat is important for the response of human body in the thermal environment. It is usually simplified as pure water when the influence of sweat on the human body temperature is studied for the prediction and evaluation of the thermal comfort. However sweat is, in reality, salt water with low concentration. Not only does the salt change the vapour pressure of the water, it may also affect the permeability of water in clothing because of the blocking of water movement by salt. This paper addresses these influences of the salt on the heat and moisture transfer in clothing. In the first part of this paper, the simultaneous heat, moisture and salt transfer in clothing is modelled in order to quantify the salt influences on the heat and moisture transfer. A sorption isotherm of a cloth of 100 % cotton is modelled taking into account salt influences and then implemented in the system of the transport equations. The second part reports on laboratory experiments of pure and salt water uptake, using sodium chloride that is the main impurity of sweat. The experimental results show that the salt water penetrates into the cloth more slowly than the pure water, which corresponds to the fact that the salt lowers the chemical potential of water. Lastly the experimental results are numerically analysed with the proposed model. A good agreement has been obtained between the calculation results and the measurement ones. The numerical analyses also indicate that the influences of the salt can not be ignored when the salt accumulates in clothing (e.g. after several sweating and drying processes).Presenters: name: Masaru Abuku affiliation: (Laboratory of Building Physics, Department of Civil Engineering, K.U.Leuven) email: masaru.abuku@bwk.kuleuven.b