CFD Simulation of Heat Transfer In an Evacuated Tube Collector

Abstract

Evacuated tube collectors (ETC) are more attractive alternative to flat plate collectors. ETC evacuated tube solar collectors convert energy from the sun into usable heat in a solar water heating system. This energy can be used for domestic and commercial hot water heating, pool heating, space heating or even air conditioning. The present study attempts to investigate the characteristic of water-in-glass evacuated tube collectors. A geometric model of the ETC and tank is prepared in ANSYS and the same is subjected to CFD analysis in Fluent. The CFD study of ETC revealed that for a 30o tilt angle, the temperature profile in the storage tank provided the maximum temperature gain due to a reduced gravitational head. For the enhancement of heat transfer within an ETC, devices such as twisted tape inserts can be employed. In the present study, the ETC was modelled and analysed with and without twisted tape inserts. The numerical study done using twisted tape inserts in an ETC collector revealed that there is an appreciable increase in storage tank temperature as compared to a simple ETC collector. Considering a width/pitch ratio of 1:1 for the twisted tape insert indicated the fastest temperature rise in the storage tank.