Experimental and Numerical studies on the Heat transfer characteristics of Small Shell and Tube Heat Exchanger

Abstract

This work presents the experimental and numerical investigations on the effectiveness of a small shell and tube heat exchanger for different coolant combinations. A numerical investigation is done using commercial computational tool, Fluent, to analyze heat transfer characteristics for the selected coolant combinations. The coolant combinations used consists of ethylene glycol (EG) and deionized water (DW) with varied percentages of the former. Accordingly, combination of ethylene glycol (EG) and deionized water viz, 60EG:40DW, 30EG:70DW and 20EG:80DW were used. The base fluids of EG and DW were used for the comparison of heat transfer characteristics, respectively with the selected coolant combination. For the numerical investigations, the CAD model of counter flow heat exchanger with 0 degree inclined baffles; with cold liquid flowing through the shell at the rate of 0.3 kg/s while hot liquid flows through the copper tubes at a flow rate of 0.3 kg/s was considered. Different combinations of shell-tube liquid are analyzed for identical initial and boundary conditions, keeping all other Fluent parameters the same. The temperature contours are generated for all the five cases. The temperature distribution for different shell-tube liquid combinations are compared for evaluating the effectiveness of heat exchange.Improved heat exchange is ensured with higher temperature difference between inlet and outlet of shell/tube, and respective combination of shell and tube fluid is selected for industrial cooling applications. Results of CFD approach are validated with the experimental results and results are acceptable. From the results it is found that 60EG:40DW combination showed improved heat transfer characteristics compared to other combinations used. Among the different coolant combinations, 60EG:40DW showed higher heat transfer as indicated by higher temperature difference across both shell and tube sections followed by other combinations when compared to pure ethylene glycol. Shell outlet and Tube outlet temperature with 60EG:40DW increased by 227% and 105% respectively when compared with pure EG, due to improved heat exchange. Heat transfer rate, heat transfer coefficient with 60EG:40DW increased when compared to pure EG.