A numerical analysis method for evaluating thermal environment in the radiant cooled space
An analytical method for evaluating a thermal radiant environment in a radiant-cooled space was developed and verified to be suitable for practical design of a comfortable radiant-cooled space. The main results are as follows:(1) The calculation method of view factors considering a complicated obstacle was developed for analyzing radiation heat transfer in the radiant-cooled space. View factors between elements are calculated by a method that combines a line-integrating method and a unique technique that enables us to understand the visibility between elements by geometrical considerations. View factors calculated by the above method were applied to analyze the thermal radiant environment in a radiant-cooled room. The mutual thermal influence between various objects was evaluated quantitatively. (2) A simplified body model was developed for evaluating heat exchange on the human body surface. The model was constructed by combining cylindrical and rectangular parts to simulate the shape of the human body accurately. The body temperature and thermal resistance of clothing were defined respectively on the basis of measured values. They were incorporated in the model as thermal properties. The validity of the model was verified by comparing analyzed body temperatures of the model with measured temperatures of real subjects.(3) A modified PMV index was proposed for evaluating the thermal sensation of occupants in the radiant-cooled space. To modify the PMV index, a new calculation process for radiation heat exchange of the human body was introduced by using the body model developed previously, and was incorporated into the original calculation process of the PMV index. The modified PMV index predicted the thermal sensation of real subjects more accurately than the PMV index. The practical validity of the modified PMV index was examined. (4) A composite evaluation method was developed by integrating the series of methods and models developed in this study. By applying the method to an actual radiant-cooled space, the influences of various building characteristics on the indoor thermal radiant environment and the thermal sensation of occupants were analyzed using the composite method. On the basis of the analysis results, some plans for improving the present situation were recommended.
|Radiation heat transfer