The impact of heat storage material integration in an evacuated tube collector

This experimental research assessed the impacts of sensible and latent heat materials such as SAE 20W/40 (used engine oil, UEO), candelilla wax (CLW), and rice bran wax (RBW) in an ETSAH (Evacuated Tube Solar Air Heater). Four distinct arrangements were studied: one without a thermal energy storage material (TESM), one with a sensible heat material (SHM), and two with latent heat materials (LHM), to enable comparative analysis. The maximum outlet temperature of air for ETC filled with UEO was 108?C, for CLW 115?C, and RBW 133?C ? all measured at 13:00. However, without filling the TESM in the ETC, the outlet temperature was only 70?C. The maximum temperature difference of the air in the RBW material-filled ETSAH system was 94?C, whereas, without TESM, the temperature was only 31?C at 13:00. The maximum efficiency of the ETSAH system was achieved when using RBW as a PCM rather than both CLW and UEO-filled TESM. Moreover, the efficiency of the system increases around 1.7?1.8 times when the velocity of air increases from 1.5 to 2.5 m/s.