| Summary: | 碩士 === 淡江大學 === 化學工程與材料工程學系碩士班 === 104 === The heat-transfer Graetz problem of a double-pass parallel-plate heat exchanger for the power-law flow subject to the hybrid boundary condition, was investigated theoretically. An impermeable barrier without thermal resistance was placed between two parallel plates, whose thermal boundaries were preset at constant temperature at one side, and constant heat flux at the other; it is called the hybrid boundary condition. In order to enhance the device performance, the recycle operation was designed between the flows in the two subchannels. The mathematical model was solved analytically using the separation of variables, together with the superposition principle and an orthogonal expansion in the power series. A dimensionless number (β) is defined as the ratio of the temperature difference between the inlet-flow and the wall at one side over the heat flux at the other side. Both theβvalue and the recycle ratio can render significant influences on the heat transfer efficiency and thus the outlet temperature from the heat exchanger. The experiments were conducted to justified the theoretical simulations. Both the theoretical and experimental results showed that the power law indices play little effect on the heat transfer of the double-pass heat exchanger in this study.
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