Experimental and numerical investigation of the effects of different parameters on a stirred heat exchanger effectiveness

Increasing energy efficiency remains crucial for both reducing adverse environmental impacts and reducing operational costs. Thermal loads and waste heat in industrial operations account for a significant portion of energy consumption. Heat exchangers play a major role in running these processes efficiently and economically. In this thesis, the effects of the mechanical stirrer's rotational speed, Reynolds number, and fluid inlet temperatures on the heat transfer performance in a stirred heat exchanger were experimentally investigated. After validating the numerical model created with computational fluid dynamics software, the impact of the stirrer's impeller and blade geometry on heat transfer performance was examined. In the numerical study, the Moving Reference Frame (MRF) for modeling the moving mesh structure and the low Reynolds corrected SST k-ω turbulence model were used for the solution in ANSYS Fluent 2022 R1 software. As a result: increasing the impeller speed from 0 to 200 rpm resulted in a 55.1% increase in heat transfer effectiveness; increasing the impeller height from H=10 mm to H=40 mm resulted in a 17.2% increase; increasing the impeller diameter from D=40 mm to D=100 mm resulted in a 15.9% increase in heat transfer effectiveness; increasing the blade angle from θ=0° to θ=45° resulted in a 14.4% increase in heat transfer effectiveness; increasing the number of blades from n=2 to n=3 resulted in a 12.6% increase in heat transfer effectiveness; and increasing the number of impellers from S=1 to S=2 resulted in a 16.7% increase in heat transfer effectiveness. The results of this thesis suggest that improving the efficiency of heat exchangers in thermal processes can lead to the development of more energy-efficient systems.