The heat packs using phase change materials (PCMs) are designed for possible applications such as body comfort and medical applications under adverse situations. The development and performance of such heat packs rely on thermophysical properties of PCMs such as latent heat, suitable heat releasing temperature, degree of supercooling, effective heat releasing time, crystallite size, stability against spontaneous nucleation in metastable supercooled liquid state and thermal stability during heating and cooling cycles. Such PCMs are rare and the available PCMs do not exhibit such properties simultaneously to meet the desired requirements. The present work reports a facile approach for the design and development of ethylene glycol (EG) and aqueous sodium acetate trihydrate (SAT) based composite phase change materials, showing these properties simultaneously. The addition of 2-3 wt% EG in aqueous SAT enhances the softness of SAT crystallites, its degree of supercooling and most importantly the effective heat releasing time by ~10% with respect to aqueous SAT material. In addition, the maximum heat releasing temperature of aqueous SAT has been tailored from 56.5 °C to 55 °C, 54.9 °C, 53.5 °C, 51.8 °C and 43.2 °C using 2%, 3%, 5%, 7% and 10 wt% EG respectively, making the aqueous SAT-EG composite PCMs suitable for desired thermal applications.The extreme low ambient temperature at high altitude regions adversely affects the health of inhabitants and may cause frostbite, hypothermia etc. Physiological alterations in the vital organs like brain, digestive and respiratory system may also occur due to the prolonged exposure to the very low temperature. Hence, it is necessary to provide the desired thermal conditions using external heating source and insulating mediums to reduce thermal losses in such situations for mitigating these problems. At present, hot water bottles, electric heating pads/blankets etc. are being used as external heat source to provide comfort in such adverse conditions 1 . The insulating mediums such as winter clothing and blankets provide relief by reducing the heat transfer rate between body and environment. However, these do not provide any heating and thus may not be suitable for longer exposure. Hot water bottles provide initial heating at higher temperature, which reduces rapidly to the lower temperatures due to the low thermal energy density of water. Thus, such heating source may provide thermal solution for a very short duration. Temperature of electric based heating devices, such as pads, blankets etc. is controlled externally using the thermostat and may lead to the causalities such as skin burn in the case of its failure. In addition, such devices are not suitable for field applications, where electrical sources may not be available. In countries like India, inhabitants use Kangaries as heat source to keep body warm during outdoor activities in high altitude regions such as Kashmir. The use of Kangaries is harmful for the health because of inhaling the toxic gases e.g.
