Numerical Study on the Saturated Flow Boiling of Methane in Vertical Pipe

In this study, a numerical study on saturated flow boiling of methane is carried out in a smooth vertical pipe. The pipe has a diameter of 8 mm and length 1 m. The simulation is performed under the condition of mass flux of 52.36-150.31 kg/㎡s, heat flux range of 7,950.7-31,858.9 W/㎡, and outlet pressure of 0.7 MPa. The analysis for saturated flow boiling is implemented with taking into account the phase change process, wall boiling and inter-phase momentum transfer models. Simulation results are compared with the theoretical values and experimental results found in the literature. According to the simulation results, the vapor quality shown in the simulation is lower than that predicted by the theoretical values. However, the variation of the vapor quality with respect to heat flux shows similar trend to the theoretical value. The heat transfer coefficient is mainly dependent on the heat flux and not significantly affected by the mass flux. This means that the main mechanism of saturated flow boiling heat transfer is nucleate boiling.