Ensayo estacional en circuito cerrado de un colector solar de aire con absorbedor poroso: simulación estacionaria bajo Simusol

Abstract

Se presentan ensayos estacionales de un calentador solar de aire con absorbedor de matriz porosa. Los ensayos se realizaron siguiendo la norma ASHRAE 93-1986, con inclinación a 33º, desde Septiembre de 2011 a Marzo de 2012, midiéndose temperatura ambiente, velocidad de viento, radiación solar global sobre plano de colector, temperatura de flujo en la entrada y salida del colector y velocidad de flujo de aire. Como resultado, se tiene flujo de aire de 0,061 kg/s a 0,068 kg/s, e incrementos de temperatura de flujo entre la salida y la entrada de 22,1°C, y eficiencias instantáneas en el rango de 0,57 a 0,65, con desviaciones estándar menores a 0,012. Un análisis del error en las predicciones de calor útil indica que la ecuación de colector plano representa adecuadamente el comportamiento del colector en días claros y parcialmente nublados. Los resultados del análisis de error son reforzados mediante una simulación térmica bajo Simusol.

The design, building and seasonal testing of an air solar collector with porous metallic absorber are presented. The collector sizes are 0.94 m wide, 2.4 m long and 0.1 m high. It was build in galvanized sheet, alveolar polycarbonate cover and porous absorber made of lightweight expanded metal mesh. Seasonal tests to determining the in-situ long-term characterization of collector were performed, following the guidelines of ASHRAE Standard 93-1986. The solar collector was connected in a closed circuit to a radiant floor and an electrical resistance of 2000 W. The collector slope was kept fixed at 33 ° to the horizontal. The tests were carried out in a span of 100 non-consecutive days, from September 2011 to March 2012. Values of temperature, wind speed, global solar radiation on collector plane, flow temperature at the inlet and outlet the collector and airflow rate were measured. The results show an airflow between 0.061 kg / s and 0.068 kg / s, with flow temperature increases between the outlet and the inlet of 11.6 ° C and 22.1 ° C, with standard deviations lesser 0.32 ° C, and instantaneous efficiencies in the range of 0.57 to 0.65, with standard deviations less than 0.01. An error analysis in predictions of useful heat indicates that the linear equation of a flat plate collector represent satisfactorily the behavior of the collector on a clear day and partly cloudy day.