Promotion of Heat Retaining of the Clothes by Dyeing Cloth with a Dye Absorbing Infrared Rays

Abstract

Heat transfer rate from a copper plate into air across the cloth dyed with a dye absorbing infrared rays was measured with and without irradiation from the infrared lamp. The copper plate was maintained at temperature of human body by hot water flown backside of the plate. Over-all heat transfer resistance of dyed cloth was larger than that of nondyed cloth, that is, the dyeing cloth promoted the heat retaining of clothes. The heat transfer resistance also increased by the irradiation from the infrared lamp. The heat transfer coefficient of air boundary film adjoined dyed cloth divided into the convectional heat transfer coefficient and the radial heat transfer coefficient by use of the convectional heat transfer coefficient obtained for a non-dyed cloth. The radial heat transfer coefficient of dyed cloth decreased to about 1/3 of that of non-dyed cloth, which might be dominant because of the promoting heat retaining of clothes. The radial heat transfer coefficient decreased by the irradiation from the infrared lamp, and the value became negative for the dyed cloth, which indicated that the absorption heat of radiation overcame the emission one. Absorption of heat irradiated from the infrared lamp, which is indicated by the difference in the radial heat transfer coefficient between without and with the irradiation of infrared lamp, increased by dyeing the cloth. This was supported by the large increase in surface temperature of dyed cloth with the irradiation from infrared lamp.