Abstract
This paper deals with the heat transfer and flow characteristics of the heat exchanger for a heat pump system using carbon dioxide as a working fluid. The heat exchanger designed as a gas cooler for high-pressure side is a counter-flow and shell-and-tube type one, 1m in length. Twenty-three copper capillary tubes, 2mm in O.D and 1.0mm in I.D., are assembled in the shell, which is a copper tube, 16mm in I.D. and 18mm in O.D. The experimental results show that the overall heat transfer coefficient of the heat exchanger is about 5 times higher than that of the concentric tube heat exchanger (comprised of a outer tube, 10.7mm in I.D., and a inner tube, 8mm in O.D.) and the pressure drop does not increase seriously.
