Investigation of the Effect of Fin Configuration and Fin Angle on Thermal Performance of Finned-Tube Heat Exchanger. Experimental Study

The influence of the configuration of flat fins on the thermal characteristics of a finned-tube heat exchanger is experimentally investigated. The configurations fins of four shapes are studied: plain (P), nozzle (N), diffuser (D), and nozzle-diffuser (ND). The bend angles of the N-fins were 10 degrees and 20 degrees, and the D-fins were 10 degrees, 20 degrees, 30 degrees, and 40 degrees. It has been established that the configuration of the finning and the angle of bending of the fins play an important role in increasing the thermal characteristics of the finned-tube heat exchanger. The main advantage of the proposed finning method in comparison with those used earlier is an increase in heat transfer practically without an increase in the coefficient of friction inside the heat exchanger tube. The scheme of the experimental setup and its main characteristics are described. The obtained experimental data on heat transfer are graphically presented. It is shown that small bending angles of the nozzle and diffuser fins significantly increase heat transfer, while angles of more than 40 degrees lead to its deterioration. A formula for calculating the Nusselt number is presented, which generalizes the experimental data for all investigated finning configurations with an error of +/- 14%.