Mechanical Expansion of Thick-Walled Microgroove Tube for High Pressure ACR System

This paper presents a study on the expansion process, which joins fins to thick-walled microgroove tubes for high pressure air conditioning and refrigeration (ACR) heat exchanger. Experiments of the tube expansion process have been carried out. An FE model with explicit algorithm is established to study the forming quality of the tube and a novel FE model with implicit algorithm is developed to investigate the local tube-fin joining status. Evaluation of the joining quality along the longitudinal axis of the tube is tried. Both FE and experimental results show that in longitudinal section, tube-fin contact is far from full contact status and internal gaps are observed. Accordingly, process parameters and expanding die geometry are examined. Results show that among the processing factors, the expanding ratio is the major factor influencing the joining status and comprehensively beneficial range of the expanding ratio is discussed.