Abstract

COETZEE, Sarel; DA VEIGA, Willem R.  and  MEYER, Josua P.. Condensation in an annulus with spiralled wires. R&D j. (Matieland, Online) [online]. 2000, vol.16, pp.51-54. ISSN 2309-8988.

There are different types of heat transfer enhancement techniques that can be used in air-conditioning and refrigeration systems to improve heat transfer, reduce heat transfer area or weight and to decrease the logarithmic mean temperature difference. Some of the heat transfer techniques are expensive and cannot be afforded by small manufacturing firms. An easy and affordable technique considered in this paper has a wire spiralled in the annulus of a water-cooled, tube-in-tube condenser, where R-22 is condensing in the annulus while the water flows through the inner tube. The purpose of this paper was to determine the heat transfer and pressure drop characteristics of the refrigerant R-22 in the annulus. Measurements were taken on four different heat exchangers, three with wires spiralled in the annulus at different angles and one without any wires used as a reference. It could be concluded that the use of the wires improved the overall heat transfer coefficient by up to 350% (45° spiral). However, as expected the pressure drop also increased, by 225%.

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