Investigation of free and forced vortex induced thermal energy exchange potential

Abstract

Recently, the gravitational water vortex flow capability to exchange heat to another fluid that circulates on the outer surface of the basin has been explored by constructing spiral flow channels (SFC). Because of the roller coaster effect, the time and area of contact between the two separate fluid streams for the sole purpose of thermal exchange limited the heat transfer. The present study proposes a new configuration that circulates the hot water in a shell with baffles (SWB) configuration around the basin. Moreover, the effect of a mixer driven by a gravitational water vortex has also been investigated to further enhance the heat transfer without the application of any external power. In short, the present study investigates and compare the heat exchange characteristics of an artificially induced free and forced vortex heat exchanger of both configurations. Each configuration has been tested by varying the hot side mass flow rates as 0.15, 0.25, 0.39, 0.7, 1.23 and 2.4 kg/s. For each mass flow rate maintained on the colder side, i.e., 0.6, 0.7, 0.8, 0.9, 1 and 1.1 kg/s, to determine the outlet temperatures of both sides. Results show that the SWB configuration for the same operating conditions is 1.32 times more effective in exchanging heat than SFC configuration. The presence of a mixer on the colder side decreases the heat transfer rate with a recorded maximum temperature drop of 2.5 K of the cold fluid. Moreover, the heat flux exchanged in the absence of a mixer for SWB and SFC configurations is 2.1 times and 1.32 times greater than those in the presence of the mixer, respectively. Therefore, the presence of the mixer on the colder side is not suitable for heat transfer enhancement in gravitational water vortex flow.