PERFORMANCE EVALUATION OF TWO KINDS OF HEAT EXCHANGERS BY USING WATER SOLUTIONS WITH FLOW DRAG REDUCTION SURFACTANT

The flow resistance of water flow could be reduced considerably by adding a small amount of flow drag reduction surfactant to water as medium. However, its addition to the water leads to reduce the overall heat transfer coefficient in a heat exchanger. In this paper, the flow and heat transfer characteristics of solution flowing in a shell & tube type heat exchanger and a plate type heat exchanger have been examined under various experimental conditions such as a water velocity and temperature in both heat exchangers. The experimental results indicated that the flow resistance and heat transfer of the water flow with surfactant in two heat exchangers were greater than those in a straight pipe. However, the flow drag reduction rate of the plate type heat exchanger was less than that of the shell & tube type heat exchanger. In relation to the plate type heat exchanger, the heat transfer reduction ratio was greater than the flow drag reduction one. The performance of both heat exchangers had been evaluated by investigating both temperature efficiency and the ratio of the amount of transferred heat to punping power.