Numerical study on performance improvement of a flat-plate solar collector filled with porous foam

Abstract

Performance improvement of a flat-plate solar collector is studied numerically using computational fluid dynamics based opensource tool, OpenFOAM. The collector channel is filled with fully saturated porous metal foam, and extended Darcy-Brinkman-Forchheimer model is used to model this porous region. The present code has been tested thoroughly against various numerical and experimental works from the literature, and a reasonable agreement is achieved. The influence of permeability (Darcy number, Da = 10−4 - 10−1), radiation insolation parameter (Rd = 0 - 5), buoyancy parameter (Richardson number, Ri = 0 - 5), and collector channel inclination angle (α = 0° - 45°) on the collector channel outlet temperature i.e., effective heating achieved has been studied. The novelty of the present study lies in the implementation of Rosseland approximation for modelling radiation influence, along with buoyancy consideration by varying channel inclination angles. The computational results suggest that the flow and thermal fields vary when modelling buoyancy and radiation influences combined. The insertion of porous metal foam enhances the thermal performance because of better thermal mixing, along with buoyancy parameter and volumetric radiation parameter. Although the performance does improve with the channel inclination angle, the maximum increment is obtained at intermediate angles, while any further rise in inclination gives a minor performance improvement. A comparison of different boundary conditions along with Rosseland approximation usage is given. A remark on the inclusion of the Forchheimer term in the present flow regime is given. The manuscript provides an impetus for further experimental work on the present case and comments on buoyancy parameter influence on channel performance. © 2019 Elsevier Ltd