Developing a hybrid procedure of one dimensional finite element method and CFD simulation for modeling refrigerant flow mal-distribution in parallel flow condenser

- A hybrid procedure for modeling refrigerant flow mal-distribution is developed.
- The proposed model has the advantage of predicting PFC overall performance.
- The experimental data of a PFC performance is used to verify the developed method.
- The effect of gravity on refrigerant flow behavior in inlet header is investigated.
- Refrigerant flow distributions among different ports of each flat tube are checked.

Mal-distribution of refrigerant flow in flat tubes is an important problem in parallel flow heat exchangers (PFHXs) which should be considered in heat exchanger modeling. In the present study, a hybrid method is developed for flow distribution forecasting based on simultaneous use of computational fluid dynamics (CFD) simulation for 3D analysis of flow in PFHX headers and one dimensional finite element model for solving flow within flat tubes. The experimental data of a parallel flow condenser (PFC) performance is collected to verify the developed method. The average absolute deviations of 2.8%, 4.1% and 3% from experimental data for pressure drop, capacity and outlet temperature respectively, indicate the model validity. Slight increase of mass flow rate with moving toward the bottom tubes of the inlet header shows insignificant effect of gravity when vapor-phase flow is present. Also, comparing the pressure drop data of the developed method with those of uniform-distribution model demonstrates reduction of average absolute deviation from 28.7% to 2.8%. The proposed model has the advantage of predicting PFC overall performance and can be used to accurately design and optimize headers and multiport flat tubes.