Experimental investigation of a novel split type vacuum tube solar air thermal collection-stepped storage system (ST-VTSATC-SSS)

A novel split type vacuum tube (VT) solar air thermal collection-stepped storage system (ST-VTSATC-SSS) is proposed in this study to address the problem of carbon and pollution emissions from coal-fired heating in rural areas. A VT air collector is used to decrease heat loss. Paraffin and lauric acid are used to conduct thermal stepped storage. The performance of ST-VTSATC-SSS is experimentally investigated. On the coldest day in winter in 2021(T_a = −2.1 °C), the collector efficiency is 61.7%, the collection-storage efficiency is 40.7%, and the heat storage is 13.7 MJ. During the thermal collection process, the thermal collection-storage efficiency can be improved by enhancing the air volume flow rate, it decreases with the enhancement of solar radiation, and it can reach 55.3%. During the thermal discharge process, increasing the air volume flow rate can enlarge the discharge power. The average discharge power can reach 904 W. The result reveals that ST-VTSATC-SSS can rapidly release heat. Besides, a heating application for the master bedroom is analyzed. In the heating season, this mechanism can save coal of 373.0 kg and reduce CO₂ by 977.3 kg, and the heating cost is 14.6 ¥/GJ. The ST-VTSATC-SSS contributes a new, clean, and low cost heating method in rural building heating.