The effects of volumetric flow rate and inclination angle on the performance of a solar thermal collector

A solar collector is a device that converts solar energy into heat. This paper presents an experimental study on the influences of volumetric flow rate and inclination angle on the performance of a solar collector. The tests were conducted on a solar energy demonstration system (ET200), which consists of a solar collector, a storage tank, a control and command cabinet and a high power lamp simulating solar energy. For radiation intensity of 1.033 kW/m2 and inclination angle of 0°, the results showed that the efficiency of the collector followed a linear relationship versus the flow rate; η = 0.68 × Qv + 49.79 and presented a coefficient of correlation (R2) of 0.9898. Similarly, the increase of the inclination angle from 0° to 60° increased the effectiveness of the collector. A linear relationship; η = 0.43 × α + 53.07 with a high coefficient of determination (R2 = 0.967) relates the collector efficiency to the inclination angle. It is important to operate at higher mass flow rates and take the collector angle at 0° in order to reach its meaning full efficiency (heating water).