The performance of a cylindrical solar water heater

A cylindrical solar water heater is designed and manufactured in the Department of Mechanical Engineering, University of Bahrain. It consists of a cylindrical tube made from high quality glass having a length of 0.8, 0.14m outer diameter and a thickness of 6mm. A copper coil tube in the shape of spiral rings, with the tube inner diameter of 2mm and outer diameter of 3.175mm, painted black, serves as a collector to the incident solar energy on the cylinder wall. The thermal performance was evaluated extensively throughout the months of March and April 2002; a maximum temperature difference of 27.8°C between inlet and outlet of the solar water heater at a mass flow rate of 9kg/h was achieved. The efficiency of the cylindrical solar water heater was calculated. The maximum value during the experimental period was found to be 41.8%. This reveals a good capability of the system to convert solar energy to heat which can be used for heating water. An economic analysis has reveals that the cylindrical solar water heater compared with the flat plate collector is cost effective.