An approximate analytical approach to steady state simulation of unglazed solar collectors

This paper illustrates the thermal modeling of a flat plate unglazed solar collector with the aim of developing a simplified but accurate method for the collector steady state simulation without requiring a large amount of computational power and time. The 1D+1D model is derived from the Riesz-Galerkin method applied to the approximate analytical solution of the heat equation. The model allows calculating heat transfer rate, fluid outlet temperature, collector efficiency and plate temperature distribution. Accuracy and ability in simulating solar collector are checked using a 2D finite-difference model as a benchmark. The results of the simplified model show very good agreement with those provided by the finite-difference model, allowing to state that the simplified model is a valuable tool for fast and reliable collector simulation.