Heat Transfer Enhancement of Tube In Tube Heat Exchanger Using Delta Winglet

Abstract

Delta winglets and inserts are used to improve the convective heat transfer coef- cient in heat exchangers. Most important area of application of delta winglets and inserts are in enhancement of heat transfer in heat exchanger. Though ns are used to increase the heat transfer of heat exchanger but in this heat transfer is increased by increasing the contact surface and not by changing the nature of ow of uid. Geometric parameters and orientations of turbulant generators signi cantly alter the ow eld and hence the convective heat transfer coe cient. The presence of the inserts and delta winglet causes ow separation, reattachment and secondary recirculation zone on the downstream side of the inserts and delta winglet. However the presence of inserts and delta winglet causes pressure drop. In the present work experimental analysis for heat transfer in Tube In Tube heat exchanger with and without inserts and delta winglet is carried out. The heat transfer augmentation in the form of Nusselt number variation is established for two different length of insert and delta winglet. Thermal performance and pressure drop for 20 cm insert, 50 cm insert and delta winglet for Reynolds numbers range of 1400 to 6500 at annulus side have been studied. Results shows that the Nusselt number for long inserts is increase by 53% and the short inserts is increase by 27% as compared with the plain tube in tube heat exchanger. Experimental analysis are extended for the delta winglets ( V- shaped inserts). Results shows that the Nusselt number for the delta winglet increases by 2% as compared to the long insert, 33% as compared to short insert and 63% as compared to plain tube.