Begell House Inc.
Multiphase Science and Technology
MST
0276-1459
13
1&2
2001
LOCAL MEASUREMENTS ON FLOW BOILING OF REFRIGERANT 12 IN A VERTICAL TUBE
111
10.1615/MultScienTechn.v13.i1-2.10
J.
Garnier
CEA/Grenoble, DEN/DTP/SETEX, 17 Ave. des Martyrs, 38041 Grenoble, France
E.
Manon
CEA/Grenoble, DEN/DTP/SETEX, 17 Ave. des Martyrs, 38041 Grenoble, France
G.
Cubizolles
CEA/Grenoble, DEN/DTP/SETEX, 17 Ave. des Martyrs, 38041 Grenoble, France
This paper presents in detail some measurements on R12 flow boiling in a vertical channel. Detailed descriptions are given of the measurement methods (and in particular the optical probes used for local void fraction on bubble characteristics). A large data bank was collected of which some characteristic samples are presented.
HEAT TRANSFER IN FORCED-CONVECTIVE TWO-PHASE FLOWS UNDER MICROGRAVITY CONDITIONS: ANALYSIS
25
10.1615/MultScienTechn.v13.i1-2.20
R. W.
Rite
Research and Development Division, TRANE Co., Wisconsin, USA
Kamiel S.
Rezkallah
Microgravify Research Group, College of Engineering, University of Saskatchewan, Saskatoon, Mechanical Engineering Dept. University of Manitoba, Winnipeg, Canada
Experimental heat transfer data collected on-board NASA’s КС-135 reduced gravity aircraft for two-phase, two-component flows in vertical, upward, co-current flow through a 9.53 mm circular tube are reported and analyzed. Data were collected for water-air flow as well as for three glycerol/water and air mixtures. It was found that for low liquid flow rates reduced gravity retards the heat transfer coefficient by up to 50% at the lowest gas qualities (bubbly and slug flow regimes). As the gas quality is increased (transition to annular flow), the difference between the 1-G and m-G heat transfer coefficients becomes smaller. At higher liquid velocities, an increase in the gas quality results in the m-G heat transfer coefficients being greater than those at 1-G by approximately 10%, which is within the uncertainty of the measurements. The influence of gravity was found to be both a single-phase effect and a two-phase effect. Mixed convection in the liquid phase affects the heat transfer coefficients, and reduced gravity has a substantial influence on the interfacial surface between the two phases. New correlations for two-phase heat transfer have been developed. These correlations include the effect of flow regime and gravity on the two phases by incorporating the non-dimensional groups of Weber, Froude, and Morton numbers. From microgravity and 1-G data, the correlations developed were found to have an uncertainty of, at most, 25% for ReST < 2300, and 15% for higher liquid superficial Reynolds numbers.
CURRENT STATE OF KNOWLEDGE ON TWO-PHASE FLOW IN HORIZONTAL IMPACTING TEE JUNCTIONS
40
10.1615/MultScienTechn.v13.i1-2.30
A. M. F.
El-Shaboury
Department of Mechanical and Industrial Engineering, University of Manitoba, Winnipeg, Manitoba, Canada
Hassan M.
Soliman
Department of Mechanical and Industrial Engineering, University of Manitoba, Winnipeg, Manitoba, Canada
G. E.
Sims
Department of Mechanical and Industrial Engineering, University of Manitoba, Winnipeg, Manitoba, Canada
The present study presents a summary of the state of the art in our understanding of the phase distribution in horizontal, equal-sided, impacting tee junctions during two-phase flow. The currently existing data base was reviewed and the effects of different parameters on the phase distribution were investigated. These parameters include the inlet superficial velocities JL1 and JG1 the inlet pressure P1, the inlet quality x1, and the inlet momentum-flux ratio MR. The available analytical models and empirical correlations were examined qualitatively and quantitatively against the data base. It is demonstrated that the available correlations and models have limited success in predicting the data. Therefore, the data base was divided into well-defined segments and the correlation or model that best predicts each segment was identified.