A modified approach for numerical simulation of capillary tube-suction line heat exchangers

This paper presents a modified approach for numerical simulations of capillary tube-suction line heat exchangers (CTSLHE). This approach is based on an approximate solution methodology previously presented. This methodology models the expansion process separately from the heat transfer process, giving rise to two sub-models, namely hydrodynamic and thermal sub-models. In the present paper, a two-step predictor-corrector model is proposed, one for the refrigerant mass flux and another for the refrigerant enthalpy path. Simulation results of mass flow rate and suction line outlet temperature were compared with experimental data, empirical correlations and well ranked distributed models. The simulation results showed good agreement with experimental data, with almost all mass flow rate results were within ±20% error bands and most suction line outlet temperature results within ±5 °C. Reasonable agreement was observed when the predicted results of mass flow rate, critical pressure and suction line outlet temperature were compared against the results from well ranked literature numerical models. Both, the influence of the capillary tube inner diameter and the suction line inner diameter over performance parameters were also investigated. No convergence problems were observed during the simulations.