Coupled Model of Heat and Mass Balance for Droplet Growth in Wet Steam Non-Equilibrium Homogeneous Condensation Flow

Han, Xu; Han, Zhonghe; Qian, Jing; Wang, Zhi

doi:10.3390/en10122033

Cited by 14 publications

(5 citation statements)

References 26 publications

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“…In the process of solving the liquid phase parameters, it is considered that the droplet temperature is not the saturated temperature corresponding to the local pressure. The droplet temperature T r can be determined by the following equation (Han et al, 2017c):…”

Section: Water Droplet Growth Modelmentioning

confidence: 99%

Numerical simulation of wet steam transonic condensation flow in the last stage of a steam turbine

Han

et al. 2018

HFF

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Purpose The purpose of this paper is to study the condensation flow of wet steam in the last stage of a steam turbine and to obtain the distribution of condensation parameters such as nucleation rate, Mach number and wetness. Design/methodology/approach Because of the sensitivity of the condensation parameter distribution, a double fluid numerical model and a realizable k-ε-kd turbulence model were applied in this study, and the numerical solution for the non-equilibrium condensation flow is provided. Findings The simulation results are consistent with the experimental results of the Bakhtar test. The calculation results indicate that the degree of departure from saturation has a significant impact on the wet steam transonic condensation flow. When the inlet steam deviates from the saturation state, shock wave interference and vortex mixing also have a great influence on the distribution of water droplets. Originality/value The research results can provide reference for steam turbine wetness losses evaluation and flow passage structure optimization design.

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Section: Water Droplet Growth Modelmentioning

confidence: 99%

Numerical simulation of wet steam transonic condensation flow in the last stage of a steam turbine

Han

et al. 2018

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“…m, u, x, τ, F D , S, and h t stand for mass generation rate, velocity component, Cartesian direction, viscous stress tensor, viscous resistance, calculation source term, and total enthalpy of gas, respectively. Combined with reference [32], the calculation formula for wetness is written as:…”

Section: Governing Equationsmentioning

confidence: 99%

Investigating the Dehumidification Characteristics of Turbine Stator Cascades with Parallel Channels

Han

Xiang

2018

Energies

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Steam turbines play a vital role in the power industry. The efficiency of the steam turbine can be improved by reforming the flow structure. For the White cascade, a parallel channel which is an additional steam passage was designed to connect adjacent steam flow channels. In view of the steepening and sensitive characteristics of the steam condensation parameters in the White cascade, the two-fluid model was applied to study the condensation and aerodynamic characteristics of the prototype cascade and the modified cascade. Wetness losses were regarded as the evaluation standard, and the optimum design of the parallel channel was obtained. The influence of channel width was also studied. The location of the suction surface (D point) has great influence on the dehumidification performance of the cascade. On the contrary, the location of the pressure surface (C point) has no significant effect on dehumidification performance. Moreover, it is necessary to select the width of the parallel channel in combination with the cascade performance. It is suggested that the parallel channel width should be between 3 and 5 mm. The research results can provide a reference for the optimal design of a turbine stator cascade.

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“…Through the application of semi-empirical correction factors, scientists can fine-tune models to achieve more precise results. Han et al [19] proposed a coupled model of the heat and mass balance for the droplet growth in wet steam homogeneous condensing flows. Their model corresponds well to the experimental data from Peter and Meyer in the transition region, the Young low-pressure correction model in the free molecular flow region and the Gyarmathy model in the continuous flow region.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of a New Droplet Growth Model for Small Droplets in Condensing Steam Flows

Shabani,

Majkut,

Dykas

et al. 2024

Energies

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As the condensation phenomenon occurs in the low-pressure stages of steam turbines, an accurate modelling of the condensing flows is very crucial and has a significant impact on the development of highly efficient steam turbines. In order to accurately simulate condensing steam flows, it is essential to choose the right condensation model. Further research to enhance condensation models is of special importance because the outcomes of numerical studies of condensation models in recent years have not been entirely compatible with the experiments and there are still uncertainties in this area. Therefore, the main aim of this paper is to evaluate a proposed droplet growth model for modelling condensation phenomenon in condensing steam flows. The new model is derived to profit from the advantages of models based on the continuum approach for large droplets and those based on the kinetic theorem for small droplets, which results in the model being robust for a wide range of Knudsen numbers. The model is implemented into a commercial CFD tool, ANSYS Fluent 2022 R1, using UDFs. The results of the CFD simulations are validated against experimental data for linear cascades within the rotor and stator blade geometries of low-pressure steam turbine stages. The findings clearly demonstrate the superiority of the new model in capturing droplet growth, particularly for very small droplets immediately following nucleation. In contrast, widely used alternative droplet growth models tend to either underpredict or overpredict the droplet growth rate. This research significantly contributes to the ongoing efforts to enhance condensation modeling, providing a more accurate tool for optimizing the design and operation of low-pressure steam turbines, ultimately leading to a higher energy efficiency and a reduced environmental impact.

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Coupled Model of Heat and Mass Balance for Droplet Growth in Wet Steam Non-Equilibrium Homogeneous Condensation Flow

Cited by 14 publications

References 26 publications

Numerical simulation of wet steam transonic condensation flow in the last stage of a steam turbine

Numerical simulation of wet steam transonic condensation flow in the last stage of a steam turbine

Investigating the Dehumidification Characteristics of Turbine Stator Cascades with Parallel Channels

Evaluation of a New Droplet Growth Model for Small Droplets in Condensing Steam Flows

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