Numerical model of the steady-state condenser and effect of pressure drop correlations on refrigerant physical parameters

Air-cooled condensers are an important part of modern refrigeration systems because they affect how well the system works and how much energy it uses. This study develops an integrated numerical model to simulate the behaviour of an air-cooled condenser using Fortran and RefProp 8.0 to evaluate the thermophysical properties of R22 and R32 refrigerants. The model solves five equations at the same time. These include the Navier-Stokes equations for the main refrigerant's mass, momentum, and energy conservation, the energy balance equation for the condenser wall, and the enthalpy equation for the secondary fluid (air). Due to the nonlinear nature of the system, the full implicit Preismann scheme was applied in conjunction with the Newton-Raphson and bisection methods to improve numerical stability and accelerate convergence. The results demonstrate that the developed model precisely forecasts the steady-state performance of the condenser, offering thorough analyses of the pressure drop and heat transfer coefficients in both the single-phase and two-phase flow regions. The effective condenser length was found to be 20 meters for R22 refrigerant and 48 meters for R32, with the two-phase zone dominating by 96%, indicating that condensation occurs primarily within this section. Furthermore, the refrigerant behaves as an incompressible fluid in the partially cooled liquid zone. Comparison with EVAP-COND 4.0 and previous studies revealed a deviation of less than ±1% in the performance parameters. These results demonstrate the long-term promise of the developed model as an effective tool for designing and optimizing air-cooled condensers for industrial refrigeration and air conditioning applications.