- Author
-
Kedzierski, M. A.
- Title
- Simultaneous Visual and Calorimetric Measurements of R11, R123, and R123/Alkylbenzene Nucleate Flow Boiling.
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Sponsor
- Department of Energy, Washington, DC
- Contract
- DE-AI01-91CE23808
- Book or Conf
- Heat Transfer With Alternate Refrigerants. HTD-Vol. 243. American Society of Mechanical Engineers (ASME). Proceedings. 1993,
27-33 p.,
1993
- Keywords
-
boiling
|
bubbles
|
lubricants
|
calorimetry
|
heat transfer
- Abstract
- Bubble formation during horizontal flow boiling of trichlorofluoromethane (R11), 1,1-dichloro-2,2,2-trifluoroethane (R123) and two R123/alkylbenzene lubricant mixtures was investigated both visually and calorimetrically. Locally measured heat transfer coefficients were taken simultaneously with high speed motion picture images of the boiling proess. The addition of a small amount (0.55%) of alkylbenzene to R123 increases the number of active nucleation sites by approximately 5 sites/cm2 which corresponds to a 12% to 50% increase in the site density. The increase in the site density contributed to the enhancement of the heat transfer coefficient of the R123/0.55% alkylbenzene mixture over that of the pure R123. Further increase in the amount of alkylbenzene to the R123 reduces the number of active sites to below that of pure R123 to approximately the value for that of R11. Consequently, the 0.55% lubricant mass fraction mixture exhibited a heat transfer coefficient that was larger than that of the 2% lubricant mass fraction mixture.