In this study, the condensation process of pure and near-azeotropic refrigerants in a horizontal multi-port tube having 17 rectangular mini-channels is investigated experimentally. The measured heat transfer coefficient is influenced mainly by the vapor shear stress and surface tension. We developed a new prediction model on heat transfer based on the following main assumptions: (1) in the annular flow region, the heat transfer correlation isexpressed as the combination of the vapor shear stress controlled term and the surface tension controlled term, (2) in the plug flow region, the heat transfer characteristic of the vapor plug is the same as the annular flow region, while that of liquid slug is the same as liquid single flow, (3) the annular flow is treated as the plug flow with the long vapor plug and the short liquid slug. The new heat transfer correlation agrees well with the experimental data of R134a, R32, R1234ze(E) and R410A in horizontal rectangular mini-channels within 40 % in deviation.
|Translated title of the contribution||Condensation of HFC and HFO Refrigerants in Horizontal Mini-Channels:－Prediction Model of Heat Transfer in Rectangular Channels－|
|Number of pages||12|
|Publication status||Published - 2012|