Begell House Inc.
Multiphase Science and Technology
MST
0276-1459
1
1-4
1982
SPRAY COOLING OF HOT SURFACES
1-97
10.1615/MultScienTechn.v1.i1-4.10
Leon
Bolle
Department of Mechanical Engineering, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
J. C.
Moureau
University Catholique de Louvain, Belgium
Heat transfer between a hot plate (600∼1100°C) and liquid sprays is experimentally and theoretically studied. Stationary experiments are carried out to investigate the sensitivity of the spray cooling effect. The liquid mass flow rate is found to have a predominant influence on the heat transfer intensity. A new theoretical model is developed by taking into account the distribution curves of droplet velocities and sizes. The predictions show good agreements with the experimental data and also suggest that models which consider only the man values can lead to large errors.
THE SPHERICAL DROPLET IN GASEOUS CARRIER STREAMS: REVIEW AND SYNTHESIS
99-279
10.1615/MultScienTechn.v1.i1-4.20
George
Gyarmathy
BBC Brown Boveri & Co., Ltd. Baden, Switzerland
This paper considers the thermodynamic and kinematic behaviour of a droplet in gaseous carrier flow. After reviewing the known (continuum-type and free-molecule type) laws of heat, mass and momentum exchange between two phases, several comprehensive expressions with multi-range validity are synthesized. In addition, a new mathematic model is developed to predict the change rate of droplet size, surface temperature and velocity. The model infers that a close analogy of heat, mass and momentum transfer is maintained at all Knudsen (Kn) numbers at any carrier density and almost any droplet size.
BOILING IN MULTICOMPONENT FLUIDS
281-386
10.1615/MultScienTechn.v1.i1-4.30
R. A. W.
Shock
Engineering Science Division, A.E.R.E., Harwell, Didcot, Oxon, England
This paper reviews the boiling characteristics of multi-component fluids. A number of features in mixture boiling, such as binary phase equilibrium thermodynamic properties, heat transfer characteristics, and critical heat flux are considered and evaluated by comparisons with experimental data. It is found that the boiling process in binary mixture can be generally related to that in pure substances with good accuracy. Hence, a number of correlations in nucleate boiling and film boiling on the heat transfer coefficient and surface superheat are postulated, to give guidance on design of efficient evaporation equipment.
CONTACT ANGLES
387-505
10.1615/MultScienTechn.v1.i1-4.40
Jacques
Chappuis
Laboratoire de Technologie des Surfaces, Ecole Centrale de Lyon, Ecully, France
This paper discusses the contact angles of a liquid drop on a solid surface in terms of mechanical considerations. A simple case (ideal homogeneous and smooth solid surface) is employed to establish several common quantities (e.g. adhesion tension, spreading coefficient). The hysteresis due to surface heterogeneity and roughness is analysed and the predicted results are compared with to those reported in literature. The methodology for accurate measurement of contact angles with a wetting tensiometer is described in detail. Finally, a new interpretation of contact angles in the case of low-energy surfaces is postulated.