Dominant dimensionless groups controlling heat transfer coefficient during flow condensation inside pipes

A study of the dominant dimensionless groups describing flow condensation at high mass fluxes inside circular pipes was performed by gathering experimental data from the literature covering a wide range of pipe diameters and fluid properties. A new model is presented based on an equivalent Reynolds number defined as the sum of the superficial liquid and vapour Reynolds numbers and an equivalent Prandtl number given as the sum of the liquid and vapour Prandtl number weighted with the thermodynamic quality. This simple model is able to capture the heat transfer coefficient of channels from a hydraulic diameter of 67 μm up to pipes of 14.45 mm in diameter for several fluids.