Theoretical and experimental study on pressure drop in two-phase flow of ammonia in a forced evaporative condenser.

This paper presents a theoretical study on the calculation of pressure drop in two-phase flow in horizontal pipes. The present study uses the two-phase frictional pressure-drop correlations that are frequently used in the corresponding scientific literature. In this respect, the: 1) homogeneous, 2) Lockhart-Martinelli, 3) Friedel, 4) Chen et al., 5) Cavallini, 6) Müller-Steinhagen & Heck and 7) Jung & Radermacher models are used, in order to compare them, to see which correlation is applicable under specific operation conditions. The theoretical results obtained by the use of seven correlations were compared with the experimental results obtained from the two-phase flow of the ammonia in a forced evaporative condenser. The experimental study was performed on a forced evaporative condenser consists of a bank of staggered coils (vertically), with smooth surface. The experiments were performed on an existing stand in the Thermodynamics Laboratory of the Technical University of Civil Engineering Bucharest .The authors present a comparative analysis of the theoretical results with experimental data.