Numerical study and experimental validation on the optimization of the large size solar collector

This work presents numerical simulations and experimental validation aimed at optimizing the design of large size flat-plate solar collectors (has a profile area of 10.04 m2). The large size collector with the advantages of high land use efficiency, compact structure, better thermal insulation and simple connection, are widely used in large scale heating systems (like seasonal storage system). Consequently, the study and optimization (thermal and antifreeze performance) of the large size collector are essential for the further application of the large size collector. However, unlike the conventional small collector, the large size collector has high flow and temperature ununiformity. The study of the large size collector should be treated differently with the conventional small collector. Meanwhile, the thermal stress induced by the temperature inhomogeneity should be studied. In this paper, we propose a numerical model of a double-glazed large size collector to evaluate the influence of the design parameters (type of absorber strips, aspect ratio, airgap thickness, number of pipes) on its thermal performance and antifreeze performance. A water-heating system with a large size solar collector is built and tested to validate the simulation model. A mechanical model is present to evaluate the thermal stress of the large solar collector and factors influencing the thermal stress of the large size collector are studied.