Exergy analysis:Tthe effect of relative humidity, air temperature and effective clothing insulation on thermal comfort

摘要

Exergy analysis enables us to make connections among processes inside the human body and processes in a building. So far, only the effect of different combinations of air temperatures and mean radiant temperatures have been studied, with constant relative humidity in experimental conditions. The objective of this study is to determine the effects of different levels of relative humidity (RH), air temperature (Ta) and effective clothing insulation on thermal comfort conditions from the exergy point of view. The performed analyses take into consideration the available data from the study by Toftum et al. (1998). The effect of different levels of RH, Ta and effective clothing insulation on human body exergy balance chain, changes in human body exergy consumption rate (hbExCr) and predicted mean vote (PMV) index were analyzed. The results show that thermal comfort conditions do not always results in lower hbExCr as it was proven in previous studies.Variations in effective clothing insulation, Ta and RH affect individual parts of human body exergy balance chain with an important effect on hbExCr. At hot and dry conditions the hbExCr is the largest while at hot and humid conditions it is the minimal. Hot and dry and cold and dry conditions have similar hbExCr. The difference appears, if the whole human body exergy balance chain is taken into consideration. To maintain comfortable conditions it is important that exergy consumption and stored exergy are at optimal values with a rational combination of exergy input and output.