INFLUENCE OF HEAT EXCHANGER EFFECTIVENESS ON THE PERFORMANCE OF THERMOSYPHON DOUBLE LOOP WATER HEATING SYSTEM

A double loop thermosyphon solar heater has been developed and its performance measured under different conditions. Absorbers in a collector are non selective and of the roll-bond aluminum type. For the required consumption hot water temperature range (40–60°C), single glazing collectors are experimentally shown to be more efficient than double glazing collectors. Heat exchanger design is found to be critical to the technical and economic performance of the water heater. The influence of the heat exchanger has been analysed in terms of the coefficient of performance-COP. It is defined as the ratio of the usable heat when the heat exchanger is used, and when the consumption water is heated directly in the collectors. The COP is smaller for higher hot water temperatures. Finally, the system is found to be more efficient for larger ratios between heat exchanger surface and collector surface.