A tube-in-tube water/zeotropic mixture condenser: design procedure against experimental data

The object of the present paper is related to the design of condensers for the non-azeotropic mixtures of refrigerants. The high temperature glide mixture R-125/236ea at three different compositions (0.30/0.70, 0.46/0.54, 0.64/0.36 by mass) was tested during condensation inside a 2 m long smooth horizontal tube-in-tube exchanger. The superheated vapour entering the tube is first cooled and then condensed against cold water flowing in the annulus. The experimental data, taken at 400 and 750 kg/ (m2 s) mass velocity, is used for comparison against the method of Colburn and Drew [Trans. AIChemE, 33 (1937) 197]. It is shown that this method gives a reasonably good prediction of the heat flux exchanged in the tube.