Experimental comparison of different heat transfer fluid for thermal performance of a solar cooker based on evacuated tube collector

A comparison of thermal performance of solar cooker with two different heat transfer fluid (HTF) and effect of gate valve on discharge process of phase change material (PCM) had been investigated experimentally. In this experimental setup, solar cooker with inbuilt thermal storage unit was connected to evacuated tube collector through connecting pipes. The available solar heat in the collector was transferred to the solar cooker by natural circulation (thermosiphon) of HTF. The water and thermal oil (engine oil) were used separately as HTF to compare the thermal performance of solar cooker. Commercial grade acetanilide was used as thermal storage material in the solar cooker. The PCM discharging process was studied, firstly when both gate valves were open and secondly when both gate valves were closed during discharging process. Then, cooking was carried out using thermal oil as HTF, and both gate valves were closed during discharging of PCM. It was found that with water as HTF, the temperature of PCM at 18:00 h was 10.7 A degrees C higher when both valves were closed as compared to the case when both valves were opened, whereas it was 13.1 A degrees C in case of thermal oil as HTF. Using thermal oil as HTF, quantity of average energy stored by PCM was increased by an amount of 18.88 % as compared to water as HTF.