Numerical investigation on the nucleate pool boiling heat transfer of R134a outside the plain tube

In the present work, a numerical method is utilized to simulate the nucleate pool boiling of R134a outside the horizontal plain tube. Eulerian multiphase model integrated with Rensselaer Polytechnic Institute (RPI) nucleate boiling model is adopted. The nucleate pool boiling is numerically investigated at the heat flux of 20–80 kW/m² and saturation temperatures of 279 and 299.7 K. By analyzing the experimental results, a modified correlation of active nucleation site density is proposed. The numerical results based on the modified correlation agree well with the experimental data of the pool boiling heat transfer outside the plain tube. According to the simulation of azimuthal variations of temperature around the tube, it is found that the region between 90° and 130° has the best heat transfer performance for its high velocity and turbulence. The maximum temperature appears at the upper of the tube because the velocity and turbulence intensity at this region are lower. The investigation helps to explain the phenomena and observed facts in the experiment.