This research aims to study the effect of tubes arrangement in the presence of condensate inundation. on steam flow resistance in a small tube bundle. In this Study, a steam condenser simulation using an air flowing over tubes with artificial water as condensate is considered. The effect of vapor suction on the pressure drop is ignored. Two staggered tube arrangements are tested experimentally a conventional staggered tube arrangement with equal transverse pitches and equal longitudinal pitches, and a suggested tube arrangement having the same dimensions as the conventional arrangement but with variable pitch. The space between pipes for the last row is kept constant for the two types of tubes arrangement The effect of transverse pitch variation and condensate inundation on the pressure drop is quantified experimentally. Numerical calculations were carried out on a one-dimensional model Of tube banks for the two arrangements. The adapted value of pressure drop coefficient C obtained experimentally was used. (C) 2009 Elsevier Ltd. All rights reserved