Experimental study of solar air heater performance by evacuated tubes connected in series and loaded with thermal storage material

摘要

? 2022 Elsevier LtdSolar air heaters (SAHs) are present for many domestic and industrial purposes, such as food drying, space heating, and solar cooking. However, the field still needs further studies on improving its performance, especially with evacuated tube solar collectors (ETSC). This work aimed to enhance the performance of the SAH device by five evacuated tubes connected in series and loaded with storage material. Two concentric aluminum pipes have been welded from below and inserted into the evacuated tube, one to enter the air and the other to load the storage materials. The proposed SAH device provides a novel design that studies heat transfer and properly expands the system operating period. The experiment results were recorded at various airflow rates, with the highest temperatures for the device outlet being 110 and 118 °C at 0.006 kg/s, respectively, with and without storage materials. During the charging process, the temperature of the storage materials reaches 95 °C. Furthermore, at an airflow rate of 0.05 kg/s, the thermal efficiency reached maximum values of 64.23 and 31.02 , with and without storage material, respectively. Also, the maximum useful power is 2836 W and 3190 W, respectively.