A numerical study of natural convective heat transfer from a shrouded vertical variable height non-isothermal fin array

•Variable height shrouded fin array has been studied undergoing natural convection.•Non-isothermal finite thickness fin is considered.•Variable height fin array predicts enhanced heat transfer than that of the fixed height.•Induced velocity increases with the decreasing variable fin height for smaller fin spacing.•Computed results of induced velocity and overall Nusselt number are correlated. Rapid removal of heat using extended surface/fin is a common practice in various engineering as well as energy-related applications. It is very much essential to examine the new design in this area for improved performance. In the present study, a numerical code is developed to study the natural convective heat transfer from a shrouded variable height non-isothermal fin array. Results indicate improved performance of shrouded variable height fin array than that of the shrouded fixed height fin array for certain conditions. For smaller fin spacing, induced velocity increases with the decreasing variable fin height. Induced velocity for the same case increases with the clearance at lower Grashof number, but at the higher value, it shows an optimum with the clearance. With the increasing fin spacing, overall heat transfer coefficient increases to a maximum which remains nearly same thereafter. Computed induced velocity and overall Nusselt number are correlated.