Pressure drop in downward flow of condensing steam over a horizontal bundle of square pitched tubes

Pressure drop measurements in a 15-row steam condenser configured with in-line tubes, p/D = 1.33, are described. Pressures from 50 to 100 mb and Re_max in the range 1,000-18,000 were imposed. It is shown that pressure loss coefficients for the bundle and for two-row pairs were lower than predictions for equivalent single-phase tests except near the bottom of the bundle. There was some evidence that increase in suction parameter increased this effect in the top rows. Taken together with previous investigations [3, 4], a falling trend of suction effect is evident the more closely packed the tubes are. The discrepancy between these findings and the results of simulation experiments [7] is noted.