Pressure drop measurements in a low pressure steam condenser with a horizontal bundle of staggered tubes

Pressure drop measurements were carried out in a test condenser of staggered configuration with p / D = 1.33. The test conditions were: steam inlet pressure, 50 mbar, inlet velocity 10-30 ms^-1 and steam-to-cooling water temperature difference 5-15 K. This corresponded to a mean bundle Re _v,max between 1000 and 7000, suction parameter range 0.3-2.8 and heat flux densities at the tube outside wall up to 79 kWm^-2. In the range 2800 < Re_v,max< 6400 increase in condensation rate progressively reduced the pressure drop coefficient to a minimum of 27-30% of the corresponding dry flow at Re_v,max = 2840 and 5320 as predicted by ESDU 74040. The results were compared with previous investigations and condensing pressure drops found comparable with Nicol et al. [Proc. 7th Int. Heat Transfer Conf. 5 (1982) 133-138] but the Fujii et al. [Int. J. Heat Mass Transfer 15 (1972) 247-260] pressure drops were always found to be lower by up to 52% than the present data. The flow patterns associated with the effect of condensation on pressure drop are discussed. The results reported here suggest that considerable errors in pressure drop, with consequent errors in heat transfer distribution, can result from ignoring the effect of suction as is currently done in condenser design and prediction. © 2004 Elsevier Ltd. All rights reserved.