Construction of a mathematical model of heat and moisture transfer in the system "person – protective clothing – external environment"

Abstract

Recent years have seen a growing demand from both researchers and industry for reliable models that can predict human thermophysiological responses. This article outlines scenarios concerning the impact of the environment on human thermal comfort, taking into account the properties of special protective clothing and the functioning of the human thermoregulation system. It provides the overview of the concept of thermal comfort and the thermoregulation system of the human body. The mathematical model should consider the complex behavior of thermophysical processes within the “person – clothing – environment” system. The heat flow between human skin and the inner surface of protective clothing is represented by a system of partial differential equations. The system is nonlinear due to the nature of human thermoregulation. The modeling encompasses both thermal and aerodynamic effects of the environment (such as temperature, air humidity, etc.), the thermal and moisture resistance of clothing, as well as heat and moisture flows to the surface of the human body resulting from internal thermoregulation. A particular challenge lies in the fact that all these processes must be modeled in an interconnected manner. Thus, the task is to move, based on mathematical models and a compartmental approach, to a quantitative assessment of the processes of mass transfer and heat of both individual parts and the human body as a whole. This problem is resolved in the work under consideration. Finite difference methods are applied to approximate spatial partial derivatives, which simplifies the problem to solving a system of nonlinear ordinary differential equations. To solve the problem, a high-precision approximation in the time dimension is used. The model is applied to predict the reaction of a clothed person to various changes in environmental conditions.

Keywords

• moisture content
• temperature
• drying
• drying coefficient
• heat transfer coefficient
• heat flux density
• moisture evaporation rate
• thermal conductivity coefficient
• bio number