Investigation of phase-change materials for interior temperature regulation in public transport

Abstract

Abstract Regulating the indoor temperature of public transport on hot sunny days is a prime concern, as both the external and internal heat sources play an active role in heat gain. Experimental studies have been carried out on a bus model using sodium sulphate decahydrate as a phase-change material (PCM) that is placed in between the ceiling and the roof. Studies are conducted on a sunny day and also for different cases of external (300-W surface heater) and internal (25-W light bulb) heat sources. The results show that PCM, in the presence of an external heat source, can help to keep the indoor temperature lower and delay the time period for increasing the temperature by absorbing heat during the phase change. On the other hand, the presence of the internal heat source contributes to a detrimental effect on the indoor temperature, which gradually increases with the elapse of time. With the combination of the external and internal heat sources, it is found that the internal heat source plays a dominating factor to raise the indoor temperature. It is revealed from the experimental results that a 12.7-mm single layer and a single PCM are not enough to counter the internal heat of 25 W unless the thickness of the PCM layer is increased to delay the increase in the indoor temperature. An additional PCM layer with a lower melting temperature could be placed at the inner portion of the ceiling to have effective thermal-energy storage by absorbing the substantial heat gain from the internal heat sources.