Response function for solar-energy collectors

The thermal behavior of a generalized solar-energy collector under transient operating conditions has been analyzed. The mathematical model employed is based on the collector's response function, which is an inherent characteristic. Due to the distribution of the fluid flow through a real collector. an analytical expression for this response function cannot easily be predicted. However, its magnitude can be readily obtained experimentally: with this, the analysis of experimental data—acquired during transient operating conditions—can then be facilitated. The method developed is applicable particularly when a step-by-step prediction of a collector's thermal behavior is required at small time intervals. This facilitates the accurate testing of solar-energy collectors under transient operating conditions. For longterm performance predictions, however, simplified models also provide satisfactory predictions. The presented analysis is not restricted to solar-energy collectors; it is also applicable to the transient thermal behavior of a wide range of open and distributed heat-processing systems. such as heat exchangers.