000053361 001__ 53361
000053361 005__ 20190316233509.0
000053361 037__ $$aARTICLE
000053361 245__ $$aIntube Flow Boiling of R-407C and R-407C/Oil Mixtures. Part 2: Plain Tube Results and Predictions
000053361 269__ $$a1998
000053361 260__ $$c1998
000053361 336__ $$aJournal Articles
000053361 520__ $$aIntube evaporation tests for R-407C and R-407C/oil are reported for a plain copper tube. The tests were run at a nominal inlet pressure of 6.45 bar (93.5 psia) at mass velocities of 100, 200 and 300 kg/m2s (73581, 147162 and 220743 lb/h ft2) over nearly the entire vapor quality range. Pure R-407C performed very similar to pure R-134a run previously in similar tests at all three mass velocities, differing only at high vapor qualities where the peaks in href vs. x were shifted slightly. For local vapor qualities from 10-70%, oil tended to have little effect on local R-407C/oil heat transfer coefficients at the lowest mass velocity while at the higher mass velocities the effect was to increase or decrease the coefficients within ±20% of the pure R-407C values. At vapor qualities higher than 70%, the effect of the oil was very dramatic, decreasing performance by as much as 80-90% even with small amounts of oil. Two-phase pressure drops were increased by the presence of oil, especially at high vapor qualities. Two methods for predicting local boiling coefficients of refrigerant-oil mixtures were presented. Using the refrigerant-oil mixture viscosity in place of the pure refrigerant viscosity in the recent Kattan-Thome-Favrat flow boiling model and flow pattern map without further modification predicted the R-134a/oil and R-407C/oil data quite accurately. The Friedel two-phase friction multiplier was found to work adequately for pure R-134a and pure R-407C. Finally a new local refrigerant- oil viscosity ratio was developed that accurately predicted two-phase pressure drops of R-134a/oil and R-407C/oil mixtures at high vapor qualities.
000053361 700__ $$aZürcher, Olivier
000053361 700__ $$0240152$$aFavrat, Daniel$$g105085
000053361 700__ $$0240577$$aThome, John R.$$g108776
000053361 773__ $$j4$$k4$$q373 - 399$$tHVAC&R Research International Journal of Heating, Ventilating, Air-Conditioning and Refrigerating Research
000053361 8564_ $$zURL
000053361 8564_ $$s2780251$$uhttps://infoscience.epfl.ch/record/53361/files/LENI-1998-006.pdf$$zn/a
000053361 909C0 $$0252044$$pLENI$$xU10315
000053361 909C0 $$0252128$$pLTCM$$xU10312
000053361 909CO $$ooai:infoscience.tind.io:53361$$pSTI$$particle$$qGLOBAL_SET
000053361 937__ $$aLENI-ARTICLE-1998-006
000053361 937__ $$aLTCM-ARTICLE-2005-049
000053361 973__ $$aEPFL$$sPUBLISHED
000053361 970__ $$aLENI-ARTICLE-1998-006/LENI
000053361 980__ $$aARTICLE