CFD study on the effect of tubes diameter and count on flow distribution uniformity in a Z disposition

Abstract

The present paper goal is to compile a comprehensive database of data on the pressure drop and flow distribution uniformity utilizing CFD in a network of parallel tubes arranged in a Z configuration adopted for flat plate solar collectors. A 3-D CFD model is implemented to simulate such a system as in the market, including two domains: tube materials and fluid, besides entering, and exiting prolonged ports. The model specifications are Z disposition of uniform inlet and outlet headers diameter (D = 20 mm), length of 1150 mm, and tube length of 1780 mm. The investigated design parameters include the number of tubes (N = 5, 10, and 15) and the tubes diameter to header diameter ratio (d/D = 0.25, 0.35, and 0.50). For a wide range of inlet Reynolds numbers from 500-5000. The present model demonstrated noticeable agreement with offered experimental findings from the literature. The results affirmed that lowering both the number of tubes and the diameter of tubes enhances the flow distribution uniformity. The findings indicate that lowering the number of tubes from 15 to 5 at a lower tubes diameter to header diameter ratio of of 0.25 at a higher Reynolds number yields a maximum increase in flow distribution uniformity of roughly 180% with a negative effect on the total pressure drop.