Carbon dioxide (R-744) is a naturally occurring substance which is environmentally benign with no ozone depletion potential and negligible global warming potential if compared to CFCs and HFCs. The supercritical heat transfer and pressure drop data for carbon dioxide in typical AC/HP equipment have not been investigated so far. This data is essential in order to design heat pump and air-conditioning equipment to be used with carbon dioxide. The objectives of this research are: to generate basic local supercritical heat transfer and fluid flow data for in-tube gas cooling of carbon dioxide for heat and mass flux ranges typical of heat pump and air-conditioning heat exchangers and, to quantify the effects of enhanced surface tubing and the effect of refrigeration oils on supercritical heat transfer coefficients, and pressure drop.

Principal Investigator: Eckhard Groll, Purdue University

Conducted: May 1997- July 1999

Sponsored by: TC 1.3, Heat Transfer and Fluid Flow