Investigation on a prototype of heat pipe type solar water heather using R 718 as working fluid

Abstract

The present work deals with experimental study on prototype heat pipe solar water heater with R718 as a working fluid. The objective is to explore the effect of the initial pressure to the performance of a heat pipe solar water heater. Three identical prototypes of the heat pipe solar water heater with collector area of 1000 mm × 500 mm have been designed and fabricated. Each solar water heater was loaded to heat the water in the tank with capacity of 5 liters of water. The refrigerant was filled to the heat pipe at three different initial pressures. They are 45 cm Hg, 40 cm Hg and 35 cm Hg, respectively. The experiments were carried out for three days. The results show that the maximum hot water temperature varies from 48.84°C to 57.49°C and thermal efficiency of the system starts from 20.03% to 28.30%. It was shown that initial pressure affects the performance. The higher initial pressure results in higher maximum temperature of the water in the tank. Based on the experiment results, the present solar water heater should be installed with initial pressure of 45 cm Hg.