Thermal comfort in air-conditioned environment with thermal radiation

Pao Yue-kong Library Electronic Theses Database

Thermal comfort in air-conditioned environment with thermal radiation


Author: Cheung, Pak-ho
Title: Thermal comfort in air-conditioned environment with thermal radiation
Degree: M.Eng.
Year: 2010
Subject: Hong Kong Polytechnic University -- Dissertations
Air conditioning -- Control
Temperature control
Dampness in buildings
Carbon dioxide
Heat -- Radiation and absorption
Department: Dept. of Building Services Engineering
Pages: xii, 84 leaves : ill. ; 31 cm.
InnoPac Record:
Abstract: Thermal comfort in air-conditioned environment is important for building occupants. The thermal sensation they experience is highly correlated to the intensity of thermal radiation. Thermal radiation involves energy exchange between surfaces (i.e. walls, ceiling, floors, furniture, etc.) as well as emission and absorption by various gases and soot particles. Among those gases of great practical importance to thermal comfort are water vapor and carbon dioxide, which are strongly absorbing-emitting in the major thermal radiation spectrum of 1 to 100 um. The objective of this study is to predict the changes in thermal comfort levels in an air-conditioned space due to thermal radiation under the influence of water vapor and carbon dioxide with different concentration inside a room. An application of box model was utilized to predict the mean radiant temperature with different concentration of H₂O and CO₂gases inside office room. The model was based on basic radiant heat transfer theories and shape factors. A measurement was carried out to validate the data derived from the model. The results of the measurement show that concentration of H₂O and CO₂gases inside office room could be a significant factor influencing the mean radiant temperature inside an office room, and hence the effects on thermal comfort level. Consequently, the results of the actual measurement and the box model showed a good correlation. The results also showed that different locations and concentration of H₂O and CO₂gases would result in different mean radiant temperature. Therefore, it draws the interest to engineers or designers that the concentration of H₂O and CO₂gases issue should be considered as an effective factor for mean radiant temperature, and hence the thermal comfort level, during the design stage. In order to illustrate the optimization work for determining the best working condition for the occupant, this study would be useful for optimizing mean radiant temperature due to the water vapor and carbon dioxide level in a room.

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