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| Author(s): |
Carlos Eduardo Keutenedjian Mady
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Escola Politécnica (EP/BC) |
| Defense date: | 2013-12-09 |
| Examining board members: |
Silvio de Oliveira Júnior;
José Guilherme de Souza Chaui Mattos Berlinck;
Silvia Azucena Nebra de Pérez;
Alvaro Toubes Prata;
Otavio de Mattos Silvares
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| Advisor: | Silvio de Oliveira Júnior; Paulo Hilario Nascimento Saldiva |
| Abstract | |
Exergy analysis is applied to the human being aiming to assess the quality of the energy conversion processes that take place in the body, its several of systems and in biochemical reactions involved in these processes. It is known that life has a beginning, a development and an end, therefore, it is a typical example if irreversible process. As the chronological age and entropic generation are positive quantities (increases in the same direction), this last one is named arrow of time. Hence, it becomes possible to obtain indices based on the concept of destroyed exergy and exergy efficiency for different areas of knowledge such as: medicine (different techniques of hypothermia), sports (ergoespirometric test) and mechanical engineer (thermal comfort). To this end, it is proposed a model of the human body which takes into account the exergy transfer rates to the environment associated with radiation, convection, vaporization and respiration. The metabolism exergy basis is calculated based on the exergy variation of the reactions of oxidation of three reference substances: carbohydrates, lipids and amino acids. For transient environmental conditions it is calculated the exergy variation of the body over time. Moreover, it is possible to calculate the maximum work that can be obtained from the hydrolysis of ATP (adenosine triphosphate). This procedure was applied to a thermodynamic model of human body for basal conditions and to experimental results of runners during different level of physical activities. The human body uses about 60% of the exergy of nutrients to obtain ATP, the rest is destroyed or dissipated as heat. Destroyed exergy rate tends to decrease as a function of lifespan (for basal conditions and during physical activities). The destroyed exergy during lifespan was calculated as 3091MJ/kg (or entropy production of 10.2MJ/kgK). The exergy efficiency decreases as a function of age in basal condition, but it increases during physical activities. The destroyed exergy rate is smaller and the exergy efficiency is greater for high operative temperatures and low relative humidities. The exergy analysis led to additional information regarding the First Law of Thermodynamics, because from its application it was possible to differentiate runners according to their training level, for the same destroyed exergy better trained subjects could perform more work. Finally it was possible to distinguish different techniques of hypothermia from the concept of exergy efficiency. (AU) | |
| FAPESP's process: | 09/17578-0 - Thermodynamic indicators for diagnosis of pathologies: applications on pathologies caused by urban environmental imbalances |
| Grantee: | Carlos Eduardo Keutenedjian Mady |
| Support Opportunities: | Scholarships in Brazil - Doctorate (Direct) |