Clothing Evaporative Resistance: Its Measurements and Application in Prediction of Heat Strain

University dissertation from Lund University (Media-Tryck)

Abstract: Popular Abstract in English Clothing plays an important role in our lives. It serves four main functions: adornment, status, modesty and protection. Wearing popular clothing with one’s favourite decorations, contributes to a person reaching his or her mental comfort. Clothing is also a symbol of status, and was particularly so in ancient times. Moreover, it protects the human body from injury from abrasions, scratches, fire, radiations, and insect bites and helps the body maintaining core temperature. From a heat transfer point of view, clothing acts as a thermal and moisture barrier. In cold weather, it is always good to have such a thermal barrier to prevent body heat loss. But in hot environments, clothing can greatly hinder sweat evaporation and heat dissipation. Construction workers and fire-fighters, for example, should wear protective clothing whatever the environment. They usually have a very high metabolic rate. If the heat produced cannot be balanced by sweat evaporation and/or dry heat losses, their body core temperature will rise. As body heat storage and core temperature increase, work performance will be greatly impaired, and the high body core temperature may eventually threaten their lives. Evaporative resistance is one of the most important factors in quantifying and characterising the role of clothing as a moisture barrier. The research reported in this thesis examined several potential factors that may cause manikin measurement errors in clothing evaporative resistance. The findings can help designers to optimise functional protective clothing. They can also be a help in standardising test protocols and in enhancing measurement accuracy. An example of using clothing evaporative resistance in a heat strain model is given. The results of human trials presented in this thesis provide a picture of how humans physiologically respond to various thermal environments and protective clothing systems. Such studies contribute to the body of knowledge on how human respond to various environments.