Condensation of refrigerants in a multiport tube with rectangular minichannels

• Condensation characteristics in a multiport tube are experimentally quantified.
• Condensation HTC of R32 is higher than those of R134a and R1234ze(E).
• The effect of hydraulic diameter on HTC in rectangular channels is clarified.
• Heat transfer model for rectangular channel is developed considering flow pattern.
• Pressured drop correlation for minichannels is proposed considering channel shape.

This study investigated the condensation heat transfer and pressure drop characteristics of refrigerants R134a, R32, R1234ze(E), and R410A in a horizontal multiport tube with rectangular minichannels, in the mass velocity range of 100–400 kg m−2 s−1 and saturation temperature set at 40 and 60 °C. The effect of mass velocity, vapor quality, saturation temperature, refrigerant properties, and hydraulic diameter of rectangular channels on condensation characteristics is clarified. A new correlation is proposed for predicting the frictional pressure drop for condensation flow in minichannels. A heat transfer model for condensation heat transfer in rectangular minichannels is developed considering the flow patterns and effects of vapor shear stress and surface tension. Then, based on this model, a new heat transfer correlation is proposed. The proposed correlations successfully predict the experimental frictional pressure drop and heat transfer coefficients of the test refrigerants in horizontal rectangular minichannels.