Numerical Simulation of Heat Transfer During Boiling Flow of Cryogenic Fluid in Vertical Tube
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Numerical Simulation of Heat Transfer During Boiling Flow of Cryogenic Fluid in Vertical Tube D. A. Gubaidullin1* and B. A. Snigerev1** (Submitted by A. M. Elizarov) 1
Institute of Mechanics and Engineering, Federal Research Center Kazan Scientific Center, Russian Academy of Sciences, Kazan, Tatarstan, 420111 Russia Received February 28, 2020; revised March 12, 2020; accepted March 21, 2020
Abstract—The two-fluid model has been extensively used in modeling boiling flow of water, however, there are few equivalent studies of boiling flow of cryogenic liquids. In the present study the two-fluid model was implemented in the OpenFOAM source code by incorporating closure correlations, which more adjustable for cryogenic liquids. Then boiling flow of liquid nitrogen in a vertical tube was numerically simulated using the modified basic model. In order to include the boiling effect, several different subroutines which model evaporation and condensation phenomena were attached to the solver. Comparison with experimental data shows that the modified model is satisfactorily improved in accuracy. This study demonstrated that the following parameters and models are important for accurate prediction: the bubble diameter frequency departure, the bubble diameter distribution and the active site nucleation density, among which, the active site nucleation density has the most significant influence. DOI: 10.1134/S1995080220070173 Keywords and phrases: two-fluid model, subcooled boiling, Euler method, simulation.
1. INTRODUCTION Cryogenic flow systems that include two-phase flow are widely used in liquefied natural gas plants, aerospace technology, superconductivity technology, and many other engineering applications. The investigation of the boiling two-phase flow characteristics of cryogenic fluids is very interesting and important not only in the basic study of the hydrodynamics of cryogenic fluid, but also in providing solutions to problems related to practical engineering applications of cryogenic two-phase flow [1–3]. Cryogenic fluids are characterized by large compressibility compared with fluids at room temperature such as water, a small difference in density between gas and liquid phases, and a small latent heat of vaporization. These unique characteristics of cryogenic contribute to obtain high performance in fluid apparatuses, such as two-phase operation of inducers. Pool boiling heat transfer is a subject of extensive research worldwide. A large number of both theoretical and empirical correlations have been proposed to predict the pool boiling heat transfer curve. The nucleate pool boiling curve is dependent on many parameters, mainly related to the thermo-physical properties of the boiling fluid and to the characteristics of the surface on which the pool boiling takes place. In particular the effect of the surface characteristics such as the thermo-physical properties of the material, geometry, thickness, orientation, surface conditions (roughness, oxidation and even the boiling cycles), require further investigation [4]. The mechanism of pool bo
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