| Summary: | 碩士 === 國立中興大學 === 機械工程學系所 === 102 === ABSTRACT
Heat transfer performance of common shell-and-tube heat exchangers is very dependent on the magnitude of the convection heat transfer coefficient of the tubes using in the heat exchanges. This work used computational fluid dynamics (CFD) simulation approach, adopting the Realizable k-ε model in the ANSYS FLUENT commercial software, to investigate the heat transfer enhancement of circular tubes with internal ring-type protrusions. By comparing the simulated result to experimental data reported in the literature, the validity of the CFD appraoch was verified. In this work, eleven sets of heat tranfer data of circular tubes with different ring-type protrusions were presented. The p/d value of the three tubes is 1.45, while the e/d values were 0.043, 0.069 and 0.1 respectively. Among the three sets of data, two were compared with the experimental data. The result (e/d =0.043) shows the error is 17 %, The result (e/d =0.069) shows the error is 3.6 %; Due to lack of experimental data for comparsion, the accuracy of the other one (e/d =0.1) is uncertain . From the three sets of data, the heat transfer characteristics of the heat tranfer enhancing tubes can be qualitatively observed. That is, for a specific tube, when Nu value increases with the Re value; for different tubes, the e/d value increases, both Nu and f values increases. The result also shows that the width of the protrusions has a minor effect on the Nu value.
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