Comparison among exergy analysis methods applied to a human body thermal model

Over the past decades, thermodynamics concepts applied to biological systems, such as the human body, have aided in explaining their functioning. The first law of thermodynamics is primarily used — from the prime research that assessed the body surface area and the temperature distribution in members to the thermal comfort conditions with Fanger methods. The second law of thermodynamics may provide new insights to this discussion because it considers the internal irreversibilities of human metabolisms to the external communications with the environment. In this study, we compared three methods to evaluate the exergy behavior of the human body with an aim to determine the thermal comfort conditions. This is defined as 30oC and 50% of relative humidity. All methods indicated equivalent points of thermal comfort conditions, thus raising the question of how to apply the exergy analysis in similar reasoning for the three models. Therefore, a distinguishing feature of this study concerns the additional contributions when applying the exergy analysis in the same human thermal model. Furthermore, we attempted to compare and suggest connections or adjustments for each method to pave the way for the realization of a unified exergy model of the human body in the future.