Pool boiling enhancement and a method of bubble diameter determination on surfaces with deep minichannels

The numerical simulation and experimental validations of the growth and departure of a single bubble on a horizontal heated surface during pool boiling under reduced gravity conditions have been performed here. A finite difference scheme is used to solve the equations governing mass, momentum and energy in the vapor liquid phases. The vapor-liquid interface is captured by level set method, which is modified to include the influence of phase change at the liquid-vapor interface. The effects of reduced gravity conditions, wall superheat and liquid subcooling and system pressure on the bubble diameter and growth period have been studied. The simulations are also carried out under both constant and time-varying gravity conditions to benchmark the solution with the actual experimental conditions that existed during the parabolic flights of KC-135 aircraft. In the experiments, a single vapor bubble was produced on an artificial cavity, 10 μm in diameter microfabricated on the polished silicon wafer, the wafer was heated electrically from the back with miniature strain gage type heating elements in order to control the nucleation superheat. The bubble growth period and the bubble diameter predicted from the numerical simulations have been found to compare well with the data from experiments.

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Pool boiling enhancement using vapor channels in microporous surfaces

International Journal of Heat and Mass Transfer ◽

10.1016/j.ijheatmasstransfer.2019.118532 ◽

2019 ◽

Vol 143 ◽

pp. 118532 ◽

Cited By ~ 3

Author(s):

Minseok Ha ◽

Samuel Graham

Keyword(s):

Pool Boiling ◽

Boiling Enhancement

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Lattice Boltzmann Simulation of Nucleate Pool Boiling in Saturated Liquid

Communications in Computational Physics ◽

10.4208/cicp.141109.161210s ◽

2011 ◽

Vol 9 (5) ◽

pp. 1347-1361 ◽

Cited By ~ 5

Author(s):

Yoshito Tanaka ◽

Masato Yoshino ◽

Tetsuo Hirata

Keyword(s):

Lattice Boltzmann ◽

Solid Wall ◽

Bubble Diameter ◽

Pool Boiling ◽

Nucleate Boiling ◽

Bubble Nucleation ◽

Immiscible Fluids ◽

Nucleate Pool Boiling ◽

Two Phase ◽

Boiling Process

AbstractA thermal lattice Boltzmann method (LBM) for two-phase fluid flows in nucleate pool boiling process is proposed. In the present method, a new function for heat transfer is introduced to the isothermal LBM for two-phase immiscible fluids with large density differences. The calculated temperature is substituted into the pressure tensor, which is used for the calculation of an order parameter representing two phases so that bubbles can be formed by nucleate boiling. By using this method, two-dimensional simulations of nucleate pool boiling by a heat source on a solid wall are carried out with the boundary condition for a constant heat flux. The flow characteristics and temperature distribution in the nucleate pool boiling process are obtained. It is seen that a bubble nucleation is formed at first and then the bubble grows and leaves the wall, finally going up with deformation by the buoyant effect. In addition, the effects of the gravity and the surface wettability on the bubble diameter at departure are numerically investigated. The calculated results are in qualitative agreement with other theoretical predictions with available experimental data.

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