TURBULENT HEAT TRANSFER IN A GROOVED U-TUBE HEAT EXCHANGER WITH VARIOUS RADIUS OF CURVATURE

In this study, convective heat transfer tests in turbulent flow regime, in a U-tube heat exchanger,were carried out. A number of factors such as isothermal friction factor, heat transfer coefficient and efficiency with respect to the ratio of slope and groove depth to the tube diameter have been determined in the experiments. Data were collected in a wide range of turbulent flow regime (60000Re> 5500), where water was used as the test fluid. The result shows that the heat transfer efficiency of exchanger used, has a significant increase as compared to the corresponding plane tubes. The average increase in the heat transfer rate is between 123 to 232 percent, depending on some variables such as Reynolds Number, tube slope and groove depth. The maximum heat transfer for the U-tube heat exchanger with e/PH=0.06 and P/PH=0.27)/ was about 2.3 times at lower Reynolds Numbers, and the friction factor1.93 times, as compared to plane tube heat exchanger. In this study, a number of variables and factors such as heat transfer coefficient, heat exchanger efficiency, friction factor, Re and Pr Numbers for the U-tube heat exchanger, over the test range, were determined and reported.

کلیدواژه ها:

heat transfer coefficient ، evaporation ، Steam quality ، radius of curvature ، U- tube ، turbulent flow ، friction factor