Enhancement of heat transfer in paraffin wax PCM using nano graphene composite for industrial helmets

Abstract

Abstract Humidity and high temperature both adversely affect the productivity of workers. At these atmospheric conditions even a safety helmet won't provide a comfortable situation for the wearer. This paper suggests a cooling system for these safety helmets using NanoGraphene (NG)/paraffin composite Phase Change Material (PCM) which absorbs and stores the heat thus achieving comfort cooling for the wearer. The heat absorbing capacity of a PCM depends on its thermal conductivity, which can be enhanced by adding different concentrations of nanoparticles. Such a technique is employed in this work, in which nano graphene is added to paraffin wax. This composite PCM is employed in an Industrial helmet for providing thermal comfort to the wearer. In principle, wearer's head transfers heat to the PCM mainly by conduction without the use of any kind of external power source. Moreover, the system maintains the wearer head temperature very close to the PCM temperature range of 28–33 °C thereby avoiding any kind of discomfort which would otherwise affect his/her alertness. It is found that the Nano-graphene/paraffin composite PCM integrated helmet provides a faster cooling compared to a normal PCM due to the changes in its thermal properties such as thermal conductivity and latent heat upon adding NG at various concentrations. Among the various tested concentration of nano graphene, the thermal conductivity of NG/paraffin composite PCM showed a maximum of 146% improved thermal conductivity and a maximum of 3% reduction in latent heat at 3% concentration of NG, when compared to those of the ordinary PCM. The designed helmet incorporated with composite PCM can provide thermal comfort to its wearer for more than four hours for all concentrations at an ambient temperature of 35 °C.