A simplified design procedure for solar collectors based on heat exchange theory

The performance of a solar collector is mathematically evaluated using heat exchanger theory instead of the solar collector efficiency method. Solar collector efficiency is shown to equal the product of collector effectiveness and the inosolation usage factor (IUF). The collector effectiveness parameter describes only the heat transfer characteristics of the collector and not the effects of operating conditions on solar collector performance. The IUF parameter describes the effect of operating conditions and is found to be a function of the transmittance-absorptance product and the ratio of minimum heat loss from the solar collector to the incident solar radiation. Results of an analysis of collector effectiveness for a flat plate solar collector with a mass flow rate of 0.6 kg/s are summarized in a nomograph, and show that the most significant factors affecting solar collector performance are the operating conditions and the collector's optical characteristics. Collector effectiveness has been found to be insensitive to changes in the design parameters over a wide range of parameter values, extrapolating thus that the method may be applied to a broad range of collector designs.