Pool Boiling of Water around Horizontal Tube to find Heat Transfer Characteristics

Description

The pool boiling phenomenon is one of the most important processes taking place in different small and large-scale industries, from petrochemical plants to gas refineries and pharmaceutical industries. In this project, pool boiling, where a cylindrical heater is located in a rectangular pool filled with water, the heater causes the water to boil and  only those molecules of water that are close to the heater's surface start boiling and are transferred to the vapor phase.

In this project, SpaceClaim has been utilized to create the geometry. Also, ANSYS Meshing has been utilized to generate a fine mesh grid. So, 92,151 cells have been generated.

Methodology

As there are several projects dealing with pool boiling in a steady or pseudo-steady state. the main purpose of the project is to focus on pool boiling in a transient solution and capture and track the vapor bubbles. The multi-phase Eulerian method has been adopted to cope with the liquid phase of water and the vapor phase of bubbles. All the drag, lift, wall lubrication, turbulent dispersion, turbulent interaction, virtual mass, and surface tension forces have been considered based on the correlations mentioned in the literature.

Furthermore, k-ɛ realizable equations have been performed to deal with the turbulent behavior of the bubble formation around the cylindrical heater. as thermal insulation walls. Still, the cylindrical heater surface has been maintained at 107 ˚C to boil the water, which is at 100 ˚C initially. Also, an adaptive time step with a minimum time of 10-5 s and an initial time step of 10-4 s has been adopted for this simulation.

Conclusion

The results confirmed that this simulation could capture the bubble formation and bubble rising as exactly as experimental works. As expected, the contours of velocity and volume fraction of vapor show that the bubbles have been formed in a thin layer around the cylinder and started moving up and rising to the pool surface.

Furthermore, the heat flux and heat transfer coefficient contours show that a large flux has been generated in the heater wall, and a large amount of heat is escaping from the heater to the water surrounding it. Finally, the heat transfer coefficient and heater wall heat flux reached 1322 W/m2K and 9055 W/m2 in this simulation.