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|Performance Analysis of Solar Air Heater having Artificial Roughness on the Absorber Plate
|Mittal, Madhup Kumar
|Solar Air Heater;Artificial Roughness
|The thermal performance of solar air heater is generally poor due to low heat transfer coefficient between the absorber plate and air flowing in the duct. In order to improve the thermal performance artificial roughness is provided on the underside of absorber plate due to which turbulence is created in the heat transfer zone and ultimately performance of solar air heater improves considerably. Present work aimed at analyzing the performance of solar air heater in terms of effective efficiency by providing different types of artificial roughness on the absorber plate. The effective efficiency has been computed by using the correlations for friction factor and heat transfer developed by various investigators for different roughness elements. Under the present study effective efficiency in the lower range of Reynolds‟s number is found to be maximum for solar air heater roughened with Dimple shaped ribs and in the higher range of Reynolds‟s number Arc shaped wires resulted in better effective efficiency. It is also found under the present study that effective efficiency attains a maximum value for dimple shaped ribs of approx. 0.8236 at Reynolds‟s no. of 12000 for relative roughness height of 0.034. In present work FEM simulation software, ANSYS version 12(workbench mode) has been used for simulation. Fluid flow (FLUENT) module has been used in present work. Fluid flow (FLUENT) module predicts the outlet temperature, velocity, flow behavior to great accuracy due to application of thermal loading on the work piece. Different types of thermal loading that can be applied on the work piece in Fluid flow (FLUENT) module are temperature, convection, radiation and heat flux. Using the Fluid flow (FLUENT) module of ANSYS heat transfer analysis was conducted on the solar air heater provided with different types of artificial roughness on the absorber plate. Simulation predicts the temperature distribution, velocity distribution and flow behavior of air flowing inside the duct. Simulation showing a little variation in results as obtained from numerical analyses which are quite acceptable. Solar air heater provided with Grooved shaped ribs gives maximum enhancement in outlet temperature of air as temperature changes from 27°C to 67°C in that case.
|M.E. (Thermal Engineering)
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