Comparative analysis on thermal-hydraulic performance of curved tubes: Different geometrical parameters and working fluids

摘要

A comparative 3-D analysis is carried out on the thermal hydraulic performance of the curved tubes namely helical, spiral, and serpentine with different geometrical parameters. Likewise, the effects of three conventional liquid working fluids namely water, engine oil, and ethylene glycol inside the tubes are investigated and compared. The results show that at the same geometrical and operating conditions, the helical tube has the best performance compared to the other ones. For all the curved tubes, the geometrical parameters at the lower values display a better performance in comparison with the higher ones. It is also detected that the working fluids with the higher Prandtl numbers have greater values of Nusselt number. However the effect of Prandtl number on the friction factor is not considerable. Finally, generalized correlations are developed for each curved tube as function of Reynolds number, Prandtl number, and geometrical parameters. It seems that the results of the current work can provide helpful guidelines for designers and manufactures in order to select the optimum curved tube, geometrical parameter, and working fluid for use in the heat exchange devises based on their specific applications in the industries such as refrigeration, automobile, chemical, food, and aerospace. (C) 2015 Elsevier Ltd. All rights reserved.