Evaluation of the Performances of Electrically Heated Clothing
Sammanfattning: Cold weather garments are necessary for people who are exposed to cold environments (below -5 °C). The weight and bulkiness of such a cold weather clothing ensemble may limit human activity and reduce the productivity. In order to solve these problems, a slim garment with a built-in heating element could be useful. The heat input power and heating efficiency are the two most important parameters for a piece of heated clothing. The input power determines how much heat can be released from the whole clothing system, while the heating efficiency demonstrates how many percent of the thermal energy could effectively contribute to wearers. However, previous studies have mainly focused on heat input power and there is a lack of knowledge about the heating efficiency of the heated clothing. In this thesis, performances of electrically heated garments were compared and evaluated on two thermal manikins. The factors that affect on the clothing heating efficiency were thoroughly studied. It was found that the ambient temperature (or temperature gradient), air velocity and clothing combination can significantly influence the heating efficiency of a heated garment. In order to make good use of the thermal energy, the heating power should be well adjusted according to the environmental conditions. The heated clothing sandwiched between underwear and jacket in a three-layer clothing ensemble is one of the most effective ways to enhance the heating efficiency. In addition, the heated clothing alters the thermal evenness of clothing ensemble due to the heat release. This gives further evidence that the serial calculation method of clothing thermal resistance does not work for heterogeneous clothing ensembles.
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