Comparative analysis of boiling and condensation heat transfer in upflow for freon R-21 in minichannels

摘要

The paper presents results of experimental investigation of heat transfer in boiling and condensation of Freon R-21 in upflow in a vertical plate-fin heat exchanger with straight and perforated fins at a small mass flow rate and heat flux, which are typical for the industry, but are insufficiently studied. Comparative analysis of heat transfer in boiling and condensation in identical conditions is performed and the influence of perforation on the heat-transfer coefficient in a wide range of equilibrium vapor quality is demonstrated.