Experimental Analysis on the Inactive region of Evacuated tube Solar Collector using Twisted Tapes

Abstract

The evacuated tube type solar collector is used predominantly for water heating application in both residential and industrial scales. They found superior in thermal efficiency compared to other kind of solar collectors. All-glass evacuated solar collector is the simplest form of evacuated collector which found its major applications as passive flow solar water heaters for residential and industrial purposes. However, they have been affected with an inherent issue which is due to the inactive region formed at the bottom of the tubes. This paper addresses this issue with the help of twisted tubes, made-up of aluminum. The experimental results proved that the existence of twisted tapes accelerated the heat transfer within the inactive region and helped to maintain the uniform temperature inside the tube. The results proved that the water temperature at the inactive region was augmented up to 73°C with the help of twisted tapes, which was 31°C more than tubes without twisted tapes. Also, the twisted tapes enhanced the average temperature of tube water by the maximum of 10°C.