Engenharia Mecânica
URI permanente desta comunidadehttps://repositorio.fei.edu.br/handle/FEI/23
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2 resultados
Resultados da Pesquisa
- Comparison among exergy analysis methods applied to a human body thermal model(2022-01-15) RIBEIRO, T. J. D. S.; Carlos Mady© 2021 Elsevier LtdOver 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.
- Exergy performance of human body under physical activities(2013) Mady C.E.K.; Albuquerque C.; Fernandes T.L.; Hernandez A.J.; Saldiva P.H.N.; Yanagihara J.I.; de Oliveira S.The aim of this work is to apply performance indicators for individuals under physical activity based on the concepts of exergy destroyed and exergy efficiency. The cardiopulmonary exercise test is one of the most used tests to assess the functional capacity of individuals with varying degrees of physical training. To perform the exergy analysis during the test, it is necessary to calculate heat and mass flow rates, associated with radiation, convection, vaporization and respiration, determined from the measurements and some relations found in the literature. The energy balance allowed the determination of the internal temperature over time and the exergy variation of the body along the experiment. Eventually, it was possible to calculate the destroyed exergy and the exergy efficiency from the exergy analysis. The exergy rates and flow rates are dependent of the exercise level and the body metabolism. The results show that the relation between the destroyed exergy and the metabolism is almost constant during the test, furthermore its value has a great dependence of the subject age. From the exergy analysis it was possible to divide the subjects according to their training level, for the same destroyed exergy, subjects with higher lactate threshold can perform more work. © 2013 Elsevier Ltd.