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This paper presents the results of numerical analysis of coupled laminar natural convection and surface radiation in a two-dimensional closed square cavity with the inversely linearly heated vertical opposite side walls and the adiabatic top and bottom walls. The cavity is filled with natural air (Pr = 0.70) as the fluid medium. In the present study, the governing equations i.e., Navier-Stokes Equation in the stream function -vorticity form and Energy Equation are solved for a constant property fluid under the Boussinesq approximation. For discretization of these equations, the finite volume technique is used. For the radiation calculations, the radiosity-irradiation formulation is used and the shape factors are calculated using the Hottel's crossed-string method. The effects of pertinent parameters like Rayleigh Number (10 3 ≤ Ra ≤ 10 6 ) and the surface emissivity of walls (0.05 ≤ε≤ 0.85) are studied and analyzed.

This analytical study has been carried out on inline and staggered hole jet plate solar air heater with longitudinal fins attached underside the absorber surface under the cross flow and non-cross flow conditions of air through the channels for varying mass flow rate of air, ṁ1 (50-300 kg/hm 2 ), jet hole diameter, D (6 mm-10 mm) and distance between the absorber and jet plate, Z2 (5 cm-10 cm) with fixed number of jet holes, N (480 and 1008 for inline and staggered hole respectively) and pitch of the fins, p (3 mm). The result shows the performance of staggered hole jet plate solar air heater with longitudinal fins under non-cross flow is better than cross flow condition. The increment of To and hPj are found higher in non-cross flow staggered hole jet plate solar air heater with longitudinal fins at smaller jet hole diameter, D (6 mm) than larger jet hole diameter, D (8 mm and 10 mm) for fixed ṁ1 (50 kg/hm 2 ). For fixed mass flow rate of air, ṁ1 (50-300 kg/hm 2 ), the outlet air temperature (To) and collector efficiency (ηc) are obtained higher at lower Z2 (5 cm) with respect to larger Z2 (6 cm-10 cm). For the fixed Reynolds number (Reja2), the required pumping power may be less or high in non-cross flow staggered hole jet plate than non-cross flow inline hole jet plate air heater with longitudinal fins attached underside the absorber surface.

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