On the performance of a mitt heating multilayer: a numerical study

Purpose - The purpose of this paper is to investigate the heat transfer on an alpine-climbing mitt featuring an electrical heating multilayer, in order to provide information for the optimization of its thermal perforniance. Design/methodology/approach - A numerical model was developed to simulate the heat transfer across an electrical-heated alpine mitt. The model was used to study the heat losses as a function of the environmental conditions, to optimise the positioning of the heating elements, to determine the optimal power input to the heating system, to estimate the battery capacity requirements and to assess the effect of low-emissivity surfaces. Findings - The results show that: the heating elements assure approximately constant temperatures across the skin provided they are not more than 6-7 mm apart; the use of low-emissivity surfaces facing the skin can reduce the total heat loss by 8-36 per cent (for air layer thicknesses in the range 10(-3) to 10(-2)m) and to increase the skin temperature during the transient operation of the heating multilayer; the heat losses from the mitt are practically independent of the chosen heating power; and a battery capacity of 4 A h assures active temperature regulation for more than 18-23 h. Practical implications - By enhancing the thermal performance of an electrical heating mitt, the use of low-emissivity surfaces (facing the skin) can favour the thermal comfort perception of its user. Originality/value - The influence of several parameters on the thermal performance of an electrical-heated mitt is analysed and discussed. The findings are relevant for improving the performance of existing electrical heating garments.