Characterization of Air-Cooled Heat Transfer Using Round and Slot Nozzles

Many industrial facilities, such as the widely used cooling tower, transfer heat to the atmosphere. The most common cooling media are water and air. The performance of cooling equipment depends upon such factors as flow rate, pressure at the nozzle tip, and the type of nozzle. In this article, round and slot nozzles with air as the cooling medium are studied to verify their cooling effectiveness. The heat transfer characteristics of these nozzles, compared using three different methodologies, are presented. A commercial computational fluid dynamics tool, FLUNET, is employed to model the 3D thermal-fluidic field of each nozzle. A 1D source code is also implemented in FORTRAN to achieve a faster and more reliable solution. Finally, experimental data are used to verify the two computational results. The difference between the results obtained using the FORTRAN code and FLUENT was about 0.07%. The temperatures at the cooling tower exit for the 1D and 3D codes were 431.9 degrees C and 432.2 degrees C (809.4 degrees F and 810 degrees F), respectively. Four sets of experimental data were compared with the numerical results. The maximum temperature difference between the 1D model and the measurements occurred at an inlet temperature of 450 degrees C (842 degrees F) and at a strip thickness of 2.28 mm. The outlet temperature from the 1D model and measurement was, respectively, 290.1 degrees C and 278.5 degrees C (554.2 degrees F and 533.3 degrees F), differing by approximately 4%. The 1D model generates good temperature predictions compared to measurements from a real cooling tower. This result would be very beneficial for industries that require fast temperature information for stable and steady operation, such as steelworks.