M.Ing. / There are two advantages of enhanced heat transfer. Firstly a decrease in the heat exchanger size and secondly an increase in the heat transfer coefficient. A method of increasing the heat transfer coefficient is to insert spiralled wires in the annulus of a tube-in-tube heat exchanger. It was decided to investigate this method further and therefore the objectives of the investigation are twofold. First to determine what the optimum spiral angle of the wires is, and secondly what mechanism causes the enhanced heat transfer. Specifically to determine if it is an increase in the turbulence or an increase in the flow rotation. A numerical model that was experimentally verified was used to do the investigation. It was concluded from the numerical results that for optimum heat transfer, the spiral angle of the wires should be 30°. It was also found that the mechanism for enhanced heat transfer is an increase in the rotation of the flow in the annulus.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:uj/uj:2188 |
| Date | 26 March 2012 |
| Creators | Krüger, E. |
| Source Sets | South African National ETD Portal |
| Detected Language | English |
| Type | Thesis |
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