Performance comparison of thermal energy storage oils for solar cookers during charging

Charging experiments to evaluate the thermal performance of three thermal energy storage oils for solar cookers are presented. An experimental setup using an insulated 20 L storage tank is used to perform the experiments. The three thermal oils evaluated are Sunflower Oil, Shell Thermia C and Shell Thermia B. Energy and exergy based thermal performance parameters are evaluated. A new parameter, the exergy factor, is proposed which evaluates the ratio of the exergy content to the energy content. Sunflower Oil performs better than the other thermal oils under high power charging. Thermal performances of the oils are comparable under low power charging. •Three solar thermal oils are evaluated experimentally.•Energy and exergy based thermal parameters are evaluated.•Sunflower Oil has best performance under high power charging at a low flow-rate.•Thermal performances obtained under low power charging are similar.•Exergy factor is an appropriate thermal performance parameter.