Evaluación experimental de la eficiencia de un colector solar de tubos evacuados sin y con tubo de calor

Abstract

This research study evaluated the efficiency of a solar evacuated tube collector (SETC) with and without a heat pipe on sunny, partially cloudy and cloudy days, experimentally. A total of 46 experiments were conducted during a period of 23 days: from March to June 2017 with two (SETC) with and without a heat pipe of 100 and 120 L, respectively. Solar radiation in the horizontal surface, and water temperature at the outlet of the storage tank were registered for 5 hours (9:30 a.m to 2:30 p.m) with intervals of 30 and 10 seconds, respectively. The Matlab programming language was used for representations and estimates of efficiency. Results show a slight superiority in the efficiency of the SETC with a heat pipe of (60,35%, 61,21% and 66,08%) compared to the one without heat pipe (57,17%, 57,29%and 59,56%), measured on sunny, partially cloudy and cloudy days, respectively. It was observed that on cloudy days, the SETC with a heat pipe presented an increase in the efficiency as a result of lower heat losses due to a lower increase in temperature thus generating a greater use of incident solar energy. The variance analysis indicated that the solar radiation and tube heat condition of the SETC do not influence significatively in the energy efficiency of this solar collector. According to the condition of solar radiation (sunny, partially cloudy and cloudy days), the SETC with a heat pipe presented a higher efficiency of 3.20%, 3.92%, and 6.52%, compared to the SETC without a heat pipe.