2014 Volume 31 Issue 2 Pages 187-198
Frost formation on the air-side surface of the air-to-refrigerant heat exchanger reduces heat transfer performance in many refrigeration systems. Typically, the design of fin-and-tube heat exchangers having large fin pitch is used because of tolerance to frost growth. In this study, a design concept of finless tube heat exchanger, which is composed of only flat tubes, was proposed for achieving high performance instead of such design of fin-and-tube heat exchangers. Heat transfer and pressure drop performance were measured to evaluate the effectiveness of the proposed heat exchanger under frosting conditions. The effects of inlet air velocity and inlet air temperature were investigated. Furthermore, the heat transfer performance of the proposed exchanger was compared with that of the fin-and-tube heat exchanger. The results showed that the heat transfer performance became much higher for the case of proposed heat exchanger compared with that for the case of fin-and-tube heat exchanger in terms of heat transfer rate per unit temperature and pressure drop penalty under no-frost and frost conditions.
