Modelling and numerical simulation of heat transfer and hydrodynamic performance of multi-pass parallel flow condensers - a novel algebraic method to determine flow distribution

In multi-pass parallel flow condensers (MPFCs), refrigerant flow maldistribution poses a significant challenge, deteriorating heat transfer performance. A robust flow distribution prediction method is crucial for the accuracy and applicability of an MPFC model. This study originally develops a new algebraic method to determine refrigerant distribution in tube-passes for MPFCs. This algorithm can be directly integrated with the authors' previously developed 2-D distributed-parameter model for MPFCs with liquid-vapor separation (MPFC-LS). The novel algorithm applies to conditions where: 1) the inlet tube of the first tube-pass is positioned arbitrarily along the vertical inlet header, and 2) the mediate headers have or lack liquid-vapor separation. The new condenser models are validated by comparing the predicted results with the experimental data of a MPFC and a MPFC-LS. The predicted heat transfer capacity and pressure drop show deviations within ±5% and ±35%, respectively. Results also reveal that the optimal position of the inlet tube is one tube pitch downward from the top of the inlet header under the given configuration and conditions. The best position of the inlet tube, compared with the worst case, improves the flow distribution by 67%, reduces the pressure drop by 68% and increases the heat transfer by 0.5%.