RADIANT EXCHANGE FOR A FIN AND TUBE SOLAR COLLECTOR

An analysis is presented to examine the radiant exchange phenomenon found in a fin and tube solar energy collector. The analysis demonstrates that the collector efficiency depends upon the tube spacing to radius ratio, fin conductance, convective coefficient, absorbed solar energy and air and surrounding surface temperatures which are employed to calculate convective and radiative losses. The collector efficiency was found to increase with tube spacing and then decrease as a result of increased fin conductive resistance. The model illustrated that accounting for surface radiation exchange yielded higher collector efficiencies at small tube spacings than those when surface radiation is neglected. Maximum collector efficiencies were found to occur for tube spacing to radius ratios between 8 and 20. Furthermore, the efficiencies were particularly sensitive to the values of air and surrounding surface temperatures.