Researchers from India have introduced a cheap material that is capable of storing heat energy collected during the day time from the sun and releasing it slowly at the night time.
The material based on stearic acid and paraffin wax is described in the upcoming issue of the International Journal of Renewable Energy Technology. This material will help to warm up the homes on sunny days without burning the flammable wood or fossil fuels, which gets colder at night times.
Meenakshi Reddy, Mechanical Engineer of Sri Venkateswara College of Engineering and Technology, and colleagues illustrate on how certain small volume phase change materials (PCM) store increased amount of heat in the latent heat form. These PCMs ensure high heat of fusion and freeze/melt at specific temperatures. These PCMs absorb and release heat when it melts and freezes respectively. The mixture of stearic acid and paraffin wax turns completely into the liquid form, when it is exposed to the sun. But when this mixture is allowed to solidify, it slowly releases the heat stored in it. This process is similar to the phase changing heating occurring in hand-warmers containing the PCM, which do not require heating or boiling in a pan or microwave oven respectively for latent heat absorption.
Meenakshi Reddy and colleagues have made an experiment using spherical capsules of 38 mm in diameter including a mixture of stearic acid and paraffin wax, which can float on the top of the water tank. Since stearic acid is found to be a cheaper material than paraffin wax in the Indian market and is readily available in the market, Reddy’s team proved that the capsule’s costs can be reduced, without any impact on the overall heating efficiency, by decreasing the paraffin’s proportion.
Source: http://www.svcetedu.org