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Modelling of temperature field of flat boiling section with active single nucleation site

Cieśliński J., T., Jasiński R., Polewski J.

Turbulence : international journal

2007

Vol. 12

65-73

The main assumptions of selected models of boiling from single cavity are presented. The ability of the models to predict heat transfer rate is discussed on the basis of own experimental data. Numerical model has been developed in order to check the commonly accepted assumption that the area of influence of nucleation site is equal to twice of departure diameter of vapour bubble as well as gain more information about heating section design used in present study. The present numerical model deals with 2D axi-symmetrical, non-isotropic heat conduction boundary problem. The finite element approach has been applied for solving heat conduction differential equation with boundary conditions of first, second and third kind, simultaneously. Boundary condition of first second kind represents heat flux density connected with bubbles generated from single nucleation site.

Formation of bubbles from a single nucleation site

Cieśliński J., Polewski J., Szymczyk J.

Archives of Thermodynamics

2002

Vol. 23, no 3

59-77

A systematic study on nucleate pool boiling from single artificial nucleation site to saturated, distilled water and methanol under atmospheric pressure is reported. Electrically heated sections have been employed to produce vapour bubbles. The cavities were drilled on a flat end of the copper rod. The diameter of the cavities was 0.25 mm and 1.0 mm, and the depth was approximately 0.40 mm and 1.6 mm, respectively. Laser-photodiode system coupled with a digital oscilloscope or a PC-audio card has been utilised for measurement of release frequency. An exposure technique for measurement of bubble size has been developed. The images of the bubbles were recorded with a CCD video camera and analysed using a commercial software.