The CFD analysis of the ICS-SWH was undertaken in order to improve the four fin ICS-SWH performance by optimising the fin spacing. Prior to simulation issues regarding the parameters influencing fin optimisation need to be determined, constrains need to be stated, heat transfer parameters need to be outlined and the type of CFD analysis need to be established.

Fin material, length and thickness and the number of fins in the ICS-SWH are the four main parameters to be outlined when analysing fin optimisation. The material thermal conductivity is an intrinsic parameter for effective ICS-SWH. The low density, high thermal conductivity and recyclable properties of aluminium highlighted this material as an effective choice. The fin length was fixed at the maximum length of 800mm. Fins are used to increase the heat transfer from the heated surface by increasing the effective surface area. The effectiveness of the fin is enhanced by increasing the ratio of the perimeter to the cross-sectional [7] therefore the use of thin, but closely spaced fins is preferred, with the provision that the fin gap is not reduced to a value where flow between the fins is severely impeded, thereby reducing the convection coefficient. The present study thus looks at the increase in performance of the ICS-SWH by increasing the number of fins.

Three main constraints affect this study; cost, volume (50litre tank size) and manufacturing ability which need to be borne in mind when choosing the new design.

Three main heat transfer parameters influence the ICS-SWH performance and can be recapitulated as: the shape of fins, the angle of inclination of the heater, and time of exposure to incident solar radiation. Due to manufacturing constraints, simple rectangular shapes of fins were considered. A 45 degree inclination angle and a 300W/m2 heat flux were taken as the reference conditions [6].

Finally, the type of CFD analysis, 2D or 3D, is an important parameter to consider. Previous studies [9] outlined that 2D analysis was sufficient for a good analysis of the system. However, 2D analysis would only suffice for a horizontal inclination of the heater. For any angle above zero a gradient exists in the longitudinal direction making a 2D analysis insufficient. Hence, based on a 45 degree inclination of the collector, a 3D analysis was undertaken. As the Quiescent fluid is unavailable in CFD simulation, the process was assumed transient.