Experimental evaluation of the efficiency of a solar tube collector evacuated with and without heat pipe
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Universidad Industrial de Santander
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En la presente investigación se evaluó experimentalmente la eficiencia de un colector solar de tubos evacuados (CSTE) sin y con tubo de calor en días soleados, parcialmente nublados y nublados. En total se realizaron 46 experimentaciones durante 23 días: marzo a junio del 2017, con dos CSTE sin y con tubo de calor de 100 y 120 L, respectivamente. La radiación solar en la superficie horizontal y temperatura del agua en la salida del tanque de almacenamiento se registraron durante 5 horas (9:30 am a 2:30 pm) en intervalos de 30 y 10 s, respectivamente. Para las representaciones y estimaciones de la eficiencia se utilizó el lenguaje de programación Matlab.
Los resultados muestran una ligera superioridad de eficiencia del CSTE con tubo de calor (60,35%, 61,21% y 66,08%) comparado al sin tubo de calor (57,17%, 57,29% y 59,56%), medidos en días soleados, parcialmente nublados y nublados, respectivamente. Y se observa que en el CSTE con tubo de calor es mayor el incremento de la eficiencia en días nublados por las menores pérdidas de calor debido a un menor incremento de la temperatura, generando un mayor aprovechamiento de la energía solar incidente. El análisis de varianza indicó que la condición de la radiación solar y tubo de calor del CSTE no influyen significativamente en la eficiencia energética de este colector solar.
De acuerdo a la condición de radiación solar (días soleados, parcialmente nublados y nublados), el CSTE con tubo de calor presentó una mayor eficiencia de 3,20 %, 3,92 % y 6,52%, respecto al CSTE sin tubo de calor.
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.
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.
Keywords
solar energy, water heating system, solar evacuated tube collector, heat pipe, efficiency, Energía Solar, Sistema de Calentamiento de Agua, Colector Solar de Tubos Evacuados, Tubo de Calor, Eficiencia