Ammonia is a strong candidate for use as a refrigerant in response to the global bans/restrictions on CFC, and HCFC compounds. There is very limited heat transfer and fluid flow data available to heat exchanger designers for condensing ammonia in enhanced tubes, and no data available for condensing ammonia with miscible oil. This research will generate data that will be valuable to engineers designing new technology refrigeration and air-conditioning equipment for various markets open to the application of ammonia (i.e., Refrigeration Condensers, HVAC Condenser Coils and Packaged Chillers, Supermarket Refrigeration Systems, etc.) Correlation of the data generated by this research will be used in condenser modeling and design.

The objectives of this research project are: a) To generate basic local two-phase heat transfer and fluid flow data for in-tube condensing of ammonia for heat and mass flux ranges typical of air-conditioning and refrigeration heat exchangers. b) To quantify the effects of enhanced surface tubing on two-phase condensing heat transfer coefficient, and pressure drop. c) To quantify the effects of miscible oils on two-phase condensing heat transfer coefficient and pressure drop. d) To develop correlation of the data in a form useful to designers and suitable for publication in the ASHRAE Fundamentals Handbook.