Experimental Investigation, Selection and Thermal Performance Evaluation of Eutectic Mixture Using PCM for Cooking Application

Abstract

Household cooking is a major energy intensive activity in most of the Ethiopian homes, and because of inefficient charcoal cooking stoves, it causes a polluting environment to the inhabitants. Hence, the electric heating stoves are rapidly replacing the current charcoal stoves. Due to lack of rain there is an extreme shortage of supply of electricity to homes, and inevitably it has become the need of the hour to provide an alternate clean renewable energy source and storage system for cooking applications. In this study, an experimental work carried out to develop a latent heat storage system consisting of different phase change materials. The theoretical results also validated with the previous research work. In this work, molten salt mixtures ware used as latent heat storage material. A thermal energy storage (TES) prototype was built with constant electrical heat input. A series of experiments were done by using this prototype to evaluate best mass proportion of molten salt mixtures. During experimentation 2 kg of molten salt mixture were used, and among all the samples two samples “NaNO3-KNO3” and “LiNO3-NaNO3” displayed melting temperatures of 225 and 202 respectively, which are well favorable for cooking applications. During experiments, it was found that, the samples with the mass fractions of “60% NaNO3-40% KNO3” and “46% LiNO3-54% NaNO3” displayed promising thermal characteristics. Moreover, charging and discharging time for 2 kg of the above mentioned phase change materials were also carried out. The charging time for the storage sample of (NaNO3-KNO3) is 19.1% faster than (LiNO3NaNO3) and which took about 30.5 minutes to bring it to 300 , while the discharging time it needs about 42.5 minutes to bring it to 150 ∘ C at the same operating conditions. Moreover, further experiments were conducted to ascertain the amount of PCM and the required thermal energy in the storage tank per day for cooking applications. The results revealed that the amount of energy required for six family members was 0.916kWh energy in order to cook lunch and dinner. Similarly, the corresponding amount of PCM was 8.7 kg.