The Effects of Oil Contamination on the Nucleate Pool-Boiling Behavior of R-114 from Enhanced Surfaces.
Abstract
The external nucleate pool-boiling heat transfer coefficient of both smooth and enhanced horizontal tubes in R-114-oil mixtures (0 to 10 mass percent oil) were measured for heat fluxes from 1 to 91 kW/sq m at a saturation temperature of 2.2 C. The enhanced tubes tested were a Wieland GEWA-T finned tube containing 1.02 fins/mm, a Hitachi Thermoexcel-E and a Hitachi Thermoexcel-HE tube. The Theromoexcel-E and -HE tubes with their reentrant cavity designs were found to improve the heat-transfer coefficient over the smooth tube value at a constant heat flux by a factor of approximately 7 in oil-free R-114, while the GEWA-T tube improved the coefficient by a factor of about 4. While all of the tubes showed a generally decreasing performance with the presence of oil, the GEWA-T tube resulted in a minimum reduction. This tube showed up to 20% and 35% reduction (compared to the oil-free case) at 3 percent and 10 percent oil, respectively. The Thermoexcel-E and Thermoexcel-HE tubes showed performance reductions of up to 40 and 60%, respectively, with 3 percent oil. At a practal heat flux of about 30 kW/sq m with 3 percent oil, the GEWA-T, Thermoexcel-E and Thermoexcel-HE tubes outperformed the smooth tube by factors of 4.8, 4.6 and 4.0, respectively.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1986
- Accession Number
- ADA174377
Entities
People
- Lloyd M. Sawyer Jr
Organizations
- Naval Postgraduate School