V. V. Kostyuk

Film-Boiling Heat Transfer

Publisher Summary Heat exchange processes, accompanied by film boiling, are widespread in such fields of technology as metallurgy, during thermal treatment of metals; radioelectronics, in temperature control of electronic equipment, and power production. Processes of heat and mass transfer for film boiling in channels, especially, for turbulent flow arc extremely complicated. The studies performed permit an understanding of the main features of these processes. In some special cases, these studies provide experimental data and techniques needed for the quantitative calculations of heat transfer and hydraulic losses. A complex of experimental studies of the structure and mechanism of two-phase flows for film boiling in channels is needed in order to develop further theoretical studies. A mathematical model consisting of a system of one-dimensional equations for each of the phases seems to be the most promising one for calculating heat transfer and hydrodynamic losses for film boiling in channels. In order to obtain a complete mathematical model, it is necessary to find from the experimental data (and in some cases, analytically) relations for the coefficients included in the model. To obtain these relations for all the modes of film boiling in channels and for conditions of mode changeover is one of the main tasks of further studies. Further experimental studies depend for their success on the methods of measuring temperature fields, velocity fields, quality, and interface configurations.

Heat Transfer in Transition Boiling of Cryogenic Liquids

Transition boiling is one of the least investigated domains of heat transfer. This is due both to the complexity of the process and to the fact that in most studies the boiling curve is investigated at fixed heat flux. Present progress in cryogenic technology and increased demands on the precision in calculations of the quenching regime have revived an interest in transition boiling. The purpose of this presentation is to summarize all experimental data known to the authors on heat transfer in the transition boiling mode and to develop a model to predict transition boiling.

Experimental and theoretical study of the transient boiling mechanism

The heat-transfer mechanism in the transition boiling region is studied theoretically and experimentally.

Cavitation boiling of various liquids

By studying transient boiling of liquids not heated to the saturation temperature and noise-type boiling of He-II a hypothesis is developed regarding the identity of these phenomena.

Generalization of test results on heat transfer in film boiling under natural convection conditions

Experimental results on heat transfer during film boiling in a large volume are compared for 13 fluids and with the computational dependences of different authors.

A mathematical model of heat transfer for forced-convective film boiling

A mathematical model of film boiling with forced convection of the liquid is discussed. A solution is obtained on a computer and is represented in the form of nomographs and approximation relations. The computed results are compared with experimental data.

A study of critical film boiling under natural convection

Results are shown of a study concerning the critical film boiling of various cryogenic liquids. The physical mechanism of this process is analyzed and recommendations are made for calculating it.

Heat transfer during film boiling of a subcooled liquid under conditions of forced flow through channels

An experimental study of heat transfer during the film boiling of subcooled liquid nitrogen in pipes with the Reynolds number Re=80,000-1,500,000 andψ=0.20–0.95 is reported.