دانلود رایگان مقاله مطالعه تجربی بر روی حس حرارتی مردم در فعالیت های متوسط

Abstract

The motivation of this study is to get better understanding about the real thermal sensations of people who undertake moderate activities. Experiments were conducted in a climate chamber. Sixteen subjects participated in two kinds of activities: treading in situ and up-and-down a step. Their metabolic rate, skin temperatures were measured. The subjects' thermal sensation votes, sweat feeling index and air movement preference were collected during experiments. The results showed that the PMV model overestimated subjects' thermal sensation for both activities. The analysis to sweat feeling index showed that subjects' thermal sensation was related to sweat activity. And the thermal regulation process of sweat had some impact on people's thermal sensation. Furthermore, the sweating process influenced mean skin temperature, which led to the decrease of neutral skin temperature at moderate activities. A linear relation was proposed to calculate the neutral skin temperature for different metabolic rate. The relation was compared with equations of Fanger and Gonzalez, which indicated that Fanger's equation strayed from the other two formulas when metabolic rate was above 2.5 met. Analysis about air movement showed that subjects expected higher velocities as activity was intensified.

5. Conclusions

In the present work, the effect of increased activity level on thermal sensation was investigated. The results showed that the prediction of PMV was accurate at sitting, yet it overestimated subjects' thermal sensation for both activity 1 and 2. So the PMV model had some deviation at higher activities and it might be improper to use PMV model to evaluate such conditions. Analysis on the effect of body movement on clothes insulation showed that dynamic clothes insulation was quite limited in explaining the overestimation of PMV. The analysis of SFI showed that subjects' thermal sensation was related to sweat activity. The sweat process enhanced evaporative heat loss, and also affected people's warmside thermal sensation. Furthermore, the sweat regulation influenced mean skin temperature, which led to the decrease of neutral skin temperature at moderate activities. A linear relation was proposed to calculate the neutral skin temperature for different heat production activities. The relation was compared with equations of Fanger and Gonzalez, which showed that Fanger's equation strayed from the other two formulas as heat production was above 2.5 met. Analysis about air movement indicated that subjects expected higher velocities as activity was intensified and the risk of draught should be considered carefully.