The growth of a vapor bubble in a superheated liquid is controlled by three factors: the inertia of the liquid, the surface tension, and the vapor pressure. As the bubble grows, evaporation takes place at the bubble boundary, and the temperature and vapor pressure in the bubble are thereby decreased. The heat inflow requirement of evaporation, however, depends on the rate of bubble growth, so that the dynamic problem is linked with a heat diffusion problem. Since the heat diffusion problem has been solved, a quantitative formulation of the dynamic problem can be given. A solution for the radius of the vapor bubble as a function of time is obtained which is valid for sufficiently large radius. This asymptotic solution covers the range of physical interest since the radius at which it becomes valid is near the lower limit of experimental observation. It shows the strong effect of heat diffusion on the rate of bubble growth. Comparison of the predicted radius‐time behavior is made with experimental observations in superheated water, and very good agreement is found.

The growth of vapor bubbles in superheated liquids. report no. 26-6

Heat transfer and friction in tubes with repeated-rib roughness

Review of drop impact on heated walls

The partitioning of the heat flux supplied at the wall is one of the key issues that needs to be resolved if one is to model subcooled flow boiling accurately. The first step in studying wall heat flux partitioning is to account for the various heat transfer mechanisms involved and to know the location at which the onset of nucleate boiling (ONB) occurs. Active nucleation site density data is required to account for the energy carried away by the bubbles departing from the wall. Subcooled flow boiling experiments were conducted using a flat plate copper surface and a nine-rod (zircalloy-4) bundle. The location of ONB during the experiments was determined from visual observations as well as from the thermocouple output. From the data obtained it is found that the heat flux and wall superheat required for inception are dependent on flow rate, liquid subcooling, and contact angle. The existing correlations for ONB underpredict the wall superheat at ONB in most cases. A correlation for predicting the wall superheat and wall heat flux at ONB has been developed from the data obtained in this study and that reported in the literature. Experimental data are within630 percent of that predicted from the correlation. Active nucleation site density was determined by manually counting the individual sites in pictures obtained using a CCD camera. Correlations for nucleation site density, which are independent of flow rate and liquid subcooling, but dependent on contact angle have been developed for two ranges of wall superheat—one below 15°C and another above 15°C. @DOI: 10.1115/1.1471522#

Onset of Nucleate Boiling and Active Nucleation Site Density During Subcooled Flow Boiling

A study of flow boiling heat transfer with refrigerant mixtures

Heat transfer to falling liquid films and film breakdown—I: Subcooled liquid films

Studies on heat transfer and flow characteristics in subcooled flow boiling. Part 2. Flow characteristics

Critical heat flux and droplet entrainment rate in boiling of falling liquid films

Experiments were made of impinging droplets on a heated vertical surface in a range of low droplet Weber numbers mostly from 10 to 200. Data of the heat transfer effectiveness of individual droplets measured by means of a transient technique are presented. When the wall superheat is higher than a certain value, the droplet rebounds away from the surface with a very low heat transfer effectiveness. Behavior of the droplets on the surface was observed and heat transfer characteristics during the residence time of a droplet on the high temperature surface were examined based on the time-dependent variation of the wall temperature measured near the surface.

Tatsuhiro Ueda

Papers

Heat transfer to falling liquid films and film breakdown—I: Subcooled liquid films

Studies on heat transfer and flow characteristics in subcooled flow boiling. Part 2. Flow characteristics

Critical heat flux and droplet entrainment rate in boiling of falling liquid films

Heat Transfer Characteristics and Dynamic Behavior of Saturated Droplets Impinging on a Heated Vertical Surface

Behaviour of liquid films and flooding in counter-current two-phase flow—Part 1. Flow in circular tubes