Numerical Investigation of Pool Boiling Under Ocean Condition with Lattice Boltzmann Simulation. Part Ⅱ: Rolling Condition

Abstract

Rolling motion caused by ocean condition will induce more complicated inertial forces with their force directions changing all the time, which results more complex bubble behaviors and unique heat transfer characteristics. In this work, pool boiling under rolling condition is numerically simulated using multiple relaxation time phase change lattice Boltzmann method (LBM). Pool boiling patterns, boiling curve of time-averaged heat flux, transient heat flux and rolling effects on different pool boiling regions are investigated. The results show that pool boiling curve of time-averaged heat flux between rolling condition and static condition are not obvious until close to critical heat flux, and 9.3% higher CHF is achieved under rolling condition while worse heat transfer is discovered at film boiling. Moreover, distinct fluctuation of transient heat flux of pool boiling under rolling condition is found for all boiling regimes, and its variation pattern along with the rolling motion and bubble behavior is investigated. Furthermore, tangential inertial force caused by rolling motion has positive influence on heat transfer of pool boiling, while the centrifugal force has negative influence on heat transfer, since it is opposite to the gravity and hence decreases the buoyancy force. Besides, larger rolling amplitude and smaller rolling period will induce larger additional inertial forces, and thus make greater influences on the bubbles’ behavior and pool boiling heat transfer.

Numerical Investigation of Pool Boiling Under Ocean Conditions with Lattice Boltzmann Simulation. Part Ⅰ: Heaving Condition

“…For research convenience, marine motions are generally decomposed to three translational motions (heaving, swaying, and surging) and three rotational motions (rolling, pitching, and yawing) (Wang et al, 2019), which are illustrated in Figure 1. Among these, heaving and rolling conditions are most commonly encountered, which will induce one kind of inertial force parallel to gravity and three kinds of inertial forces, respectively, and their effects on the work fluid inside the marine applications would produce unique thermal-hydraulic characteristics, which will be studied in this study series with Part Ⅰ focused on heaving conditions and Part Ⅱ (Zou et al, 2021) concentrated on rolling conditions. In recent decades, studies about thermal-hydraulic characteristics of marine applications under heaving conditions have been focused on flow circulation or flow boiling (Tian et al, 2020), which were mainly applied to the marine reactors (O'Rourke, 2010).…”

“…Moreover, results and discussion are implemented in the Results and Discussion Section, where the mechanism of pool boiling under heaving conditions is shown, with conclusions drawn in the Concluding Remarks Section. Besides, it is noteworthy that the methodology and results in this study serve a reference for the investigation of pool boiling under rolling conditions in Part Ⅱ of this study series (Zou et al, 2021), which provides a comprehensive study of pool boing under complex marine conditions together.…”