Abstract
In order to ensure the overall thermal comfort of the human body, one must make sure that a constant balance is maintained between the processes of thermogenesis and thermolysis. Therefore, the quantity of heat produced within our bodies in a given period of time must be equal to the quantity lost by various means (conduction, convection, evaporation, radiation) in the same time interval. Much of the heat that the human body generates is lost through clothing; thus, one should pay attention when choosing apparel products in order to make sure that the clothing maintains an adequate thermal balance. Calculating the thermal properties of clothing structure consists in determining the value of the total thermal transfer coefficient Kimp (Kcal/m2hoC), and the value of the thermal resistence coefficient Rimp (m2hoC/Kcal). The determining algorythm is complex and time-consuming. This paper proposes a software application that consists of a data basis in which a range of activities are specified (sleeping, standing, light work, moderate work, hard work, walking etc.), with certain values for: the amount of heat lost by the human body while undergoing these activities U(Kcal/h), environment temperature (oC), body height (cm) and weight (Kg). When the user selects the type of activity and the specific body indicators, the application automatically displays the amount of heat lost through clothing by means of thermal flow q(Kcal/m2hoC), total thermal transfer coefficient Kimp (Kcal/m2hoC), thermal yield indices, thermo-isolation capacitance indices, and the value of heat resistance imposed for the clothing structure Rimp (m2hoC/Kcal). By using another software application for calculating the heat transfer taking place within a clothing assembly, it can be calculated the thermal resistance values Rcalc (m2hoC/Kcal) and the total thermal transfer coefficient Kcalc (Kcal/m2hoC) for a fezable item suited for the designated activity.
By comparing the calculated values of thermal resistance for the clothing items to those imposed by the body state, it can be concluded whether the said items correspond to their intended purposes or not. The smaller the difference between Rcalc (m2hoC/Kcal) Rimp (m2hoC/Kcal), the better the choice of clothing for the designated activity of the human body is. |