Capillary tubes, suction line heat exchanger, mathematical modeling, algebraic solution
The present work advances an algebraic model for predicting the suction line outlet temperature and the mass flow rate in diabatic capillary tube flows. The proposed solution improved the functionality of an existing model, without significantly increasing the complexity of its implementation. The approach introduced in this paper assumes the refrigerant flow in the capillary tube as adiabatic to describe the two-phase temperature profile. By doing so, the ordinary differential equation governing the energy conservation in the suction line can be solved analytically. The model predictions for the refrigerant mass flow rate and the temperature difference through the suction line were compared against 51 experimental data points, showing errors within 10% and 15% bounds, respectively. Nonetheless, it was observed that the experimental dataset was restricted to the cases where heat transfer takes place also in the single-phase region of the capillary tube. Therefore, model validation for cases where heat exchange takes place exclusively in the two-phase region is still to be performed.