Forced-convection heat and mass transfer from humid air to roped tubes

Prosperi, Roberto (1997) Forced-convection heat and mass transfer from humid air to roped tubes. MSc(R) thesis, University of Glasgow.

Abstract

The results of experimental measurements of forced-convection heat and mass transfer from hot, humid air to three spirally indented (roped) tubes are presented. Comparisons are also made with experimental results for an equivalent plain tube. An experimental rig was built which allowed for the varying of the two main experimental values of gas free-stream velocity and air humidity content. Filmwise condensation on the horizontally-mounted, 12 mm diameter tubes was studied at nominal air-vapour mixture Reynolds numbers of 1100, 2100 and 4600. Water vapour concentrations ranged from 0 to 24% by weight. Modest condensation enhancement was found for two of the roped tubes while the third tube showed little or no improvement relative to the plain tube. The gas-side enhancements found for the most-highly-grooved 2-start tube were similar to those for the 6-start tube at all three mixture velocities tested. The average enhancement over the vapour concentration range was between 7 and 15%, with the degree of enhancement increasing with increasing mixture velocity. The dual mechanisms of improved condensate drainage and increased boundary layer mixing are presented as factors which account for this enhancement. The experimental data suggests the predominance of the latter effect at the relatively low condensation rates seen here. Additionally, a computer program was developed to simulate the plain-tube condensing case under the same conditions considered in the experimental study. A very satisfactory comparison with the experimental results confirms the consistency of the theory as well as the suitability of the chosen simulation method. An example of the successful extension of the program to roped tubes is also provided.

• Item Type: Thesis (MSc(R))
• Qualification Level: Doctoral
• Subjects: T Technology > T Technology (General)
• Colleges/Schools: College of Medical Veterinary and Life Sciences
• Supervisor's Name: Cunningham, Mr. J.
• Date of Award: 1997
• Depositing User: Enlighten Team
• Unique ID: glathesis:1997-74287
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 11 Jul 2019 14:35
• Last Modified: 17 Oct 2022 12:59
• Thesis DOI: 10.5525/gla.thesis.74287
• URI: https://theses.gla.ac.uk/id/eprint/74287