The effect of plate spacing in plate heat exchanger design as a condenser in organic Rankine cycle for low temperature heat source

Plate spacing is one of variable that influences plate heat exchanger (PHE) design as a condenser in Organic Rankine Cycle (ORC) system. The rises of plate spacing have effects to channel cross sectional area, channel velocity, equivalent diameter, and Reynold number at hot and cold fluid sides in PHE. Those parameters affect the total heat transfer area and total pressure drop that influence the PHE condenser performance. This paper investigated the detail effect of the plate spacing increments in the final total heat transfer area and total pressure drop design result. The plate spacing in design calculation method is varied and the other independent variables are assumed to be constant. The design was conducted by calculating condenser capacity at both sides and both zones, estimating overall heat transfer coefficient, and calculating heat transfer area and plate film coefficient. Analysis continued by calculating overall heat transfer coefficient that has small percent of error with the estimated overall heat transfer coefficient, calculating pressure drop, total plate number and total heat transfer area. The result of calculation shows that the rises of plate spacing increase the total heat transfer area and decrease the cold and hot fluid total pressure drop. The rises of plate spacing increase channel cross sectional area and equivalent diameter, and decrease channel velocity and Reynold number at zone 1 (without phase change) and zone 2 (with phase change). Therefore, the increment of heat transfer areas is unpreferable and the decrement of pressure drops is preferable. (C) 2015 The Authors. Published by Elsevier Ltd.