Development of a Low-Cost Heat Pipe Solar Thermal Collector

Abstract

The objective of this research is to develop a low-cost heat pipe solar thermal collector. A 1.5 m² flat-plate solar thermal collector equipped with 12 heat pipes as heat transfer elements to the water manifold was designed and tested. The performance of the solar thermal collector was tested following the ASHRAE standard 93-77. The following water flow rates in the manifold were adjusted; 40, 60, and 80 L/hr.  The current results show that the water outlet temperature greatly depends on solar radiation intensity and the water flow rate in the manifold. The maximum water outlet temperature of 53°C can be achieved when the water flow rate of 40 L/hr. and average solar radiation of 3.95 kw/m² were applied. A maximum thermal efficiency of 55.61% can be reached when the water flow rate of 80 L/hr. and the average solar radiation of 3.39 kW/m² were applied. From the analysis, the maximum total heat loss of the collector of 3.40 W/m² can be found at the water flow rate of 40 L/hr. followed by the total heat loss of 2.60 W/m² at a water flow rate of 60 L/hr. and 1.63 W/m² at a water flow rate of 80 L/hr., respectively. From the simple economic analysis, a payback period of 1.35 years was obtained for this low-cost heat pipe-solar thermal collector. This is found to be a shorter payback period compared with that of the conventional commercial flat plate solar collector (2.25 years) and the vacuum solar collector (1.54 years).