Abstract:
There is a need to develop the proper heat transfer correlation for CO2 flow condensation due to its high enthalpy of vaporization, thermal conductivity and specific heat compared to other substituted refrigerants at low temperatures. A boundary-layer analysis type correlation was proposed. The eddy diffusivity of momentum models of von Karman, Spalding and Prandtl-Taylor were implemented in a numerical simulation of annular flow condensation, and comparison to CO2 experimental heat transfer data showed that the predictions of inner velocity and temperature distributions by the Prandtl-Taylor model had the best agreement with experiment. The frictional pressure drop model of Müller-Steinhagen and Heck was used in conjunction with the Prandtl-Taylor model based on the thermal law of the wall to provide the main structure of the annular flow condensation correlation. The manipulation resulted in a non-empirical correlation for CO2 annular flow heat transfer, which showed very good agreement to the CO2 experimental data with an average absolute deviation of 9.2%.