Effect of inclination on flooding and heat transfer during reflux condensation in a small diameter tube

The effect of inclination on the flooding point as well as on the heat transfer coefficient during reflux condensation in a small diameter tube is investigated. The inner diameter of the tube is 7 mm and the length is 500 mm. The test fluids for the flooding experiments are refrigerant R134a and steam, the test fluid for the heat transfer experiments is R134a. It has been found that the inclination angle has a significant effect not only on the flooding point but also on the heat transfer coefficient in the R134a tests. The optimum inclination angle at which the highest flooding vapour velocity can be reached is between 45degrees and 60degrees from the horizontal. The optimum inclination angle for the heat transfer was found to be about 40degrees. (C) 2002 Elsevier Science Ltd.