Heat Transfer Enhancement in Pipe in Pipe Heat Exchanger with Swirling Flow: Review

Heat transfer enhancement in heat exchangers finds much industrial importance because it gives an opportunity to reduce heat transfer surface area required for a given application and thus reduce the heat exchanger size and cost. Commonly used heat transfer enhancement methods are Active, Passive & Compound. In most of applications and key areas like power plants, process & chemical industries uses surface enhancement methods which are the type of passive method. Twisted tape inserts, coil wire, dimpled and extended surfaces are the most effective heat transfer enhancement techniques used due to their easy manufacturing & installation at lower cost, but these methods are only effective in laminar regions. Active & compound methods are rarely used because of their complexity & cost. Very few researchers made their contribution for the Active methods which involves the fluid injection in main bulk fluid & tangential injection of the fluid with effective swirl generation. In case of turbulent flow applications we have lot of scope to concentrate on the active techniques like injection and jet impingement. Present work mainly emphasis on the broad review of various heat transfer intensification techniques which involves different means induces swirling flow for heat transfer enhancement.