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Abstract <p>Bulk condensation is one of the frequently encountered and exploited processes in the technologies of gas purification from impurities. The phase transition process can be conditionally divided into stages of the droplet formation and growth due to two simultaneously acting mechanisms, namely, continuing vapor condensation on the surface of formed droplets and droplet coagulation due to their collisions. Early computational estimates in regard to coagulation showed a good qualitative agreement between the calculated and experimental data, but there was a significant quantitative difference. Within the framework of the present study, a hypothesis about a possible reason of these differences is put forward: turbulent disturbances are not considered in the one-dimensional formulation. The main aim is to test the hypothesis on the need to take turbulence into account within the framework of the calculation model for expanding flow in which bulk condensation takes place. The proposed modification of the approach makes it possible to take into account the effect of turbulent disturbances on coagulation of condensation aerosol particles. This can be essential, for example, in vapor–liquid turboexpanders. The study considers the bulk condensation of heavy water vapor mixed with nitrogen, acting as a non-condensable carrier gas, in the flow part of a Laval slot nozzle with regard to coagulation and turbulence. The hypothesis on the effect of turbulence in the system of gas dynamics equations on the process of droplet (particle) coagulation of a condensing impurity in the flow is confirmed. It is found that taking turbulence into account significantly improves the numerical convergence of calculations and experiment; however, it does not provide exact agreement, which, in turn, may be caused by the adopted assumption of the Brownian coagulation approximation, as well as the use of the <i>k</i>–ω turbulence model. It is shown that taking turbulence into account affects the magnitude of the coagulation kernel, the maximum difference for calculations with and without turbulence being approximately 10%. Taking into account turbulence during coagulation, droplets (particles) grow to larger sizes, which in the long term makes it possible to control this process.</p>

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On the Influence of Turbulence on the Coagulation of Droplets in the Process of Bulk Condensation in Vapor–Gas Flow

  • 期刊论文

  • 发表日期：

    2025年12月1日

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  • A. A. Sidorov,
  • A. K. Yastrebov

摘要

Abstract

Bulk condensation is one of the frequently encountered and exploited processes in the technologies of gas purification from impurities. The phase transition process can be conditionally divided into stages of the droplet formation and growth due to two simultaneously acting mechanisms, namely, continuing vapor condensation on the surface of formed droplets and droplet coagulation due to their collisions. Early computational estimates in regard to coagulation showed a good qualitative agreement between the calculated and experimental data, but there was a significant quantitative difference. Within the framework of the present study, a hypothesis about a possible reason of these differences is put forward: turbulent disturbances are not considered in the one-dimensional formulation. The main aim is to test the hypothesis on the need to take turbulence into account within the framework of the calculation model for expanding flow in which bulk condensation takes place. The proposed modification of the approach makes it possible to take into account the effect of turbulent disturbances on coagulation of condensation aerosol particles. This can be essential, for example, in vapor–liquid turboexpanders. The study considers the bulk condensation of heavy water vapor mixed with nitrogen, acting as a non-condensable carrier gas, in the flow part of a Laval slot nozzle with regard to coagulation and turbulence. The hypothesis on the effect of turbulence in the system of gas dynamics equations on the process of droplet (particle) coagulation of a condensing impurity in the flow is confirmed. It is found that taking turbulence into account significantly improves the numerical convergence of calculations and experiment; however, it does not provide exact agreement, which, in turn, may be caused by the adopted assumption of the Brownian coagulation approximation, as well as the use of the k–ω turbulence model. It is shown that taking turbulence into account affects the magnitude of the coagulation kernel, the maximum difference for calculations with and without turbulence being approximately 10%. Taking into account turbulence during coagulation, droplets (particles) grow to larger sizes, which in the long term makes it possible to control this process.