Design, Fabrication and Testing of a Laboratory Scale Bare and Finned Inside Tubes Double Pipe Heat Exchangers

Author : Nono, Lemuel Del Rosario
Major Adviser : Demafelis, Rex B.
Committee Members :
Year : 1990
Month : March
Type : Thesis
Degree: BS
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A laboratory scale bare and finned inside tubes double pipe heat exchangers were designed, fabricated and tested. The materials used in the construction were PVC pipe for the outer tube and copper tube for the inner tube. The fins attached made use of copper sheet cut into strips. The design was constructed at DAMET shop and tested at the Chemical Engineering Unit Operations Laboratory.

During the testing, hot water was allowed to pass inside the inner tube while the cold water was flowed countercurrently through the annular space. Two final trials were made for each setup; the first trial was at low hot water flowrate and the second at higher hot water flowrate while keeping the cold water flowrate constant for the two trials.

The convective and over-all heat transfer coefficients were computed based from the data gathered. Results showed that heat transfer coefficients, both the convective and overall, increased as the flowrate of the streams were increased. It was also found out that the computed values of convective heat transfer coefficient of outside of tube, ho, and the over-all heat transfer coefficient, Ui, for finned inside tube were higher compared to the bare inside tube. The computed fin efficiency was 79%.

It was concluded that the finned inside tube is a better heat exchanger due to higher over-all heat transfer coefficient obtained as compared to the bare inside tube.

The design was recommended for refinement such that the velocity of the streams can be measured easily.

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