HEAT TRANSFER ENHANCEMENT USING CIRCUMFERENTIAL FINNED TWISTED TAPE HEAT EXCHANGER
Keywords:Augmentation, Reynolds Number, Nusselt Number, Shear Stress, Friction Factor, Thermal Performance Factor
The most desirable feature in any thermal equipment is the enhancement of heat transfer. Heat transfer is basically a slow process and is enhanced by adopting passive or active methods of enhancement. In passive enhancement methods, heat transfer is increased without demanding any external power source; while in active method, enhancement in heat transfer demand external power. In this work, a passive enhancement method is proposed and tested to check the extent of heat transfer enhancement noticed. A tube in shell heat exchanger is designed with circumferential fins attached along the length of tube and a spiral insert running inside the tube. One fluid is made to flow inside the tube under the influence of twisted tape and the shell side fluid is running around the tube continuously provoked by fins. Therefore, the hot and cold fluids were estimated to exchange more heat because of thorough mixing initiated in their flow paths. In this work, analysis was made in CFD package by creating a model that simulates experimentations observed in the literature. The results of experiments and results of CFD analysis were compared. Noticing the agreement between the results, the CFD model is given enhancements like circumferential fins and twisted tape to check the enhancement in heat transfer. The velocity and temperature contours were observed at various flow conditions (Reynolds numbers). Based on results of analysis, thermal performance factor is also estimated to check the increment in heat transfer with reference to hydraulic (or flow) parameters.
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