Effect of the shape of connecting pipes on the performance output of a closed-loop hot water solar Thermo-syphon

In order to conserve the environment from pollution, which is caused by the use of the fossil fuels, numerous research works have been carried out in renewable energy area to minimize the dependency on the fossil fuels. There are several energy sources naturally available, and solar energy is considered to be the best amongst them. Therefore it became a motivating area for the researchers in recent years. Thermo-syphon is one of many devices that use solar energy for power generation. Thermo-syphon converts solar energy into internal energy of the working fluid; mainly water. In this work, a computational fluid dynamics (CFD) code has been used to analyse the natural convection phenomenon in a thermo-syphon. The thermo-syphon model consist of steel pipes with an internal diameter of 25mm, along with a condenser having diameter equal to five times the pipe’s diameter, has been considered. The study has been carried out under no-loading conditions, for two thermo-syphon models comprising of straight and helical shaped pipes of 10, 20 and 30. A practical solar heat flux of 500W/m2 has been applied on the pipes. The numerical results depict that the working fluid within the condenser, in case of helical pipes, gains higher temperature as compared to the straight pipes. Furthermore, increase in the number of helical pipes has negligibly small effect on the temperature of the fluid within the condenser, and hence on the performance output of the thermo-syphon.