Numerical Study on Temperature Distribution of Water-in-Glass Evacuated Tubes Solar Water Heater

Zaw Min Thant, Myat Myat Soe, Maw Maw Htay

This A numerical study on water-in-glass evacuated tube solar collector using Computational Fluid Dynamics (CFD) is presented in this work. The water-in-glass evacuated tube is an integral part of evacuated tube solar water heater. The water-in-glass collector is the mostly used form of evacuated tube collector because it has higher thermal efficiency and simple construction requirements and hence low manufacturing cost. The usage of evacuated tube collectors is increasing day by day. Thus, several works have been published for representing the stratification of the fluid inside the tubes and the reservoir, as well as analytical modelling for the heat flow problem. Based on recent publications, this paper proposes the study of solar water heating with evacuated tubes, their operation characteristics and operating parameters. To develop this work, a computational tool will be used-in this case, the application of computational fluid dynamics (CFD) software. The commercial software ANSYS-CFX® was used for the CFD simulation of the temperature distribution of water-in-glass evacuated tube solar water heater, which uses the Finite Volume Method (FVM).  The objective of this work is to complement the studies cited earlier, approaching the transient analysis of an evacuated tube collector with different inclinations  geometries and different tube dimensions geometries , to allow better heat removal from the tube and to evaluate the behaviour of the fluid within this solar collector and possible improvements to be applied in the model. In this work,  the model with three different inclinations (30°, 45°, 60°)and same tube dimension (47D1800L) is described and then the model with different dimension(47D1200L, 34D1400L) for same inclination is also simulated. According to the simulation results, length and diameter (47D1800L) and inclination angle 45° model is the best.