Fundamental Study on the Exergy-Entropy Process of Buildng Environmental Control Systems

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The conventional theories associated with how building environmental conrtol systems work are only based on the law of energy conservation. We have tried to extend the theory into the one which includes the law of entropy generation and the associated concept, exergy. We have made simple example calculation in terms of room air temperature variation caused by solar radiation transmitted through windows on a day in winter and water spraying over exterior wall surfaces. Following are the findings.1. The ratio of the exergy to the energy of solar radiation is between 80 and 90%.2. The exergy contained by the long-wave effective sky radiation always comes at at the outer surface of exterior walls. Its amount is about 1W/m^2 in summer in Japan.3. We classified the exergy of humid air into warm, cool, wet, and dry exergies. According to this classification, the liquid water in humid air as the environment contains either warm or cool exergy and wet exergy. It was found that the evaporative cooling is a process that consumes the wet exergy of water and ther by produce the cool exergy.4. The extinction coefficient for the trees were estimated from the measured solar radiation and the solar position. The proposed method to estimate the solar radiation coming through the tree was tested against the resultof the field measuremant. Solar radiation estimated was in good agreement with that measured. The measured room air temperature was compared with the calculated room air temperature and both temperatures were in good agreement.5. It was found that the earth has a system to dispose of all the entropy generated by the earth surface due to the consumption of solar exergy for various puposes including passive heating and cooling.