Exergy Analysis and Human Body Thermal Comfort Conditions: Evaluation of Different Body Compositions.

Matheus Martinez Garcia,Silvio De Oliveira Junior,Carlos Eduardo Keutenedjian Mady,Rafael Yoshimori Une

doi:10.3390/e20040265

Matheus Martinez Garcia, Silvio De Oliveira Junior + Show 2 more

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https://doi.org/10.3390/e20040265

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Abstract

This article focuses on studying the effects of muscle and fat percentages on the exergy behavior of the human body under several environmental conditions. The main objective is to relate the thermal comfort indicators with exergy rates, resulting in a Second Law perspective to evaluate thermal environment. A phenomenological model is proposed of the human body with four layers: core, muscle, fat and skin. The choice of a simplified model is justified by the facility to variate the amount of mass in each tissue without knowing how it spreads around the body. After validated, the model was subjected to a set of environmental conditions and body compositions. The results obtained indicate that the area normalization (Watts per square meter) may be used as a safe generalization for the exergy transfer to environment. Moreover, the destroyed exergy itself is sufficient to evaluate the thermal sensation when the model is submitted to environmental temperatures lower than that considered for the thermal neutrality condition (and, in this text, the thermal comfort) . Nevertheless, for environments with temperatures higher than the calculated for the thermal neutrality, the combination of destroyed exergy and the rate of exergy transferred to the environment should be used to properly evaluate thermal comfort.

Highlights

The Laws of Thermodynamics describe different types of phenomena in several research areas.Common examples are found in chemistry, astrophysics, materials science and engineering
The last subsection focus on relating the thermodynamic data with thermal comfort conditions
A distinguished feature of this analysis is the modification of the person anatomy and the direct comparison between the exergy destruction rate with Predicted Mean Vote (PMV) and Predicted Percent Dissatisfied (PPD)

Summary

Introduction

The Laws of Thermodynamics describe different types of phenomena in several research areas. Common examples are found in chemistry, astrophysics, materials science and engineering. Law of Thermodynamics demonstrates that there must be an impact in the environment wherever a non-equilibrium is present. As discussed by [1], it is this unbalance that guarantees life. A few decades later [2] demonstrated that all living beings tend to a minimum entropy production level. Several Thermodynamic approaches to biological systems have been performed in the past decades. There is the study of a single cancerous cell [3], protocols in hypothermia techniques [4], and an analysis of physical activities [5,6,7]. There is a review article gathering these new applications as in Ozilgen [8]

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