CFD evaluations on bundle effects for steam condensation in the presence of air under natural convection conditions

Bian, Haozhi; Sun, Zhongning; Cheng, Xiang; Zhang, Nan; Meng, Zhaoming; Ding, Ming

doi:10.1016/j.icheatmasstransfer.2018.09.003

Cited by 26 publications

(5 citation statements)

References 19 publications

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“…where T air,in,inlet and T air,in,outlet are the mass-weighted average temperatures of the air at the inlet and at the outlet of the pipe section, respectively, K. Finally, the convective heat transfer coefficient for the air inside the tube is derived using the Nusselt number Nu air,in h air,in = Nu air,in v air,in d pipe (7) where v air,in is a mean air velocity in the pipe, m/s. The Nusselt number for the finned side of the pipe is based on the correlations for cross flow over tube bundles [ (8) where Re air,out is the Reynolds number defined on the basis of maximum velocity that occurs in the pipe bundle (as the flow cross section area decreases due to existence of the pipes having external diameter D pipe ), Pr air,out stands for the Prantdl number defined for the temperature T bundle,av , while Pr pipe,wall is the Prantdl number defined for the temperature T pipe,wall,av .…”

Section: Heat Transfer Coefficientsmentioning

confidence: 99%

“…Although limited when it comes to condensation hoods, the literature describes profusely the unit processes regarding other applications and appliances. The most important phenomena in terms of the condensation efficiency are: the model of condensation of the air-steam mixture coupled with the species transportation process [4][5][6][7][8], the heat transfer in externally-finned pipes with plain circular fins [9][10][11][12][13][14], and also tube bundle configuration analysis [15][16][17][18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

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Development of a Condensation Model and a New Design of a Condensation Hood—Numerical and Experimental Study

et al. 2021

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The development of a numerical model and design for the innovative construction of a heat exchanger (HE) used in a condensation hood (being a part of the combi-steamer) are described in this work. The model covers an air-steam flow, heat transfer, and a steam condensation process. The last two processes were implemented with the use of an in-house model introduced via User Defined Functions (UDF). As the condensate volume is negligible compared to the steam, the proposed model removes the condensate from the domain. This approach enabled the usage of a single-phase flow for both air and steam using a species transport model. As a consequence, a significant mesh and computation time reduction were achieved. The new heat exchanger is characterised by reorganised fluid flow and by externally finned pipes (contrary to the original construction, where internally finned pipes were used). This allowed a reduction in the number of the pipes from 48 to 5, which significantly simplifies construction and manufacturing process of the HE. The redesigned HE was tested in two cases: one simulating normal working conditions with a combi-steamer, the other with extremely high heat load. Measurement data showed that the numerical model predicted condensate mass flow rate (3.67 g/s computed and 3.56 g/s measured) and that the condensation capability increased at least by 15% when compared to the original HE design.

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Section: Heat Transfer Coefficientsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Development of a Condensation Model and a New Design of a Condensation Hood—Numerical and Experimental Study

et al. 2021

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“…35-Calculate the global heat transfer (K2). 36-Calculate mean absolute error (MAE) values [18,19], using coefficients K2 and K1.…”

Section: -Verify Inmentioning

confidence: 99%

New Procedure for Thermal Assessment of an Air Cooled Condenser Coupled to Biomass Power Plant

Camaraza-Medina¹,

Sánchez-Escalona²,

Retirado-Mediaceja³

et al. 2020

IJSDP

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In the present times, the use of air cooled condenser (ACC) has become generalized where the installation of power plants is required and access to condensation water is difficult. At present it is known that performing the thermal evaluation of an ACC is a complex task, since the existing methods do not consider all the elements that directly influence the performance of the ACC. A very widespread method is that attributed to Kröger, however its use does not provide adequate results for high values of environmental temperature, which is a limitation to be applied in tropical countries like Cuba. This document provides an analysis method that includes the effect of environmental variables and that allows reasonable results to be obtained for high values of ambient temperature. The new proposal follows the logical sequence of the Kröger method, but considering a new procedure for the determination of the mean heat transfer coefficients and pressure drops, required for the thermal evaluation of ACC.

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“…The behavior of countercurrent two-phase flows, which can be accurately predicted through three-dimensional (3D) computational fluid dynamics (CFD) codes, has critical implications for the safety and efficiency of the associated processes. CFD is widely used in many fields, such as evaluation of steam condensation heat transfer effects (Bian et al, 2018;Bian et al, 2019) and aerodynamic design of aircraft (Yang and Yang, 2012), etc., ANSYS Fluent is a commercial CFD software application that is highly universal and contains a variety of optimized physical models. In ANSYS Fluent, a broad range of mathematical models for multiphase phenomena is available, and the software can model complex geometries that are being increasingly used in both engineering practice and academic research (ANSYS Fluent, 2019).…”

Section: Introductionmentioning

confidence: 99%

Numerical modeling of horizontal stratified two-phase flows using the AIAD model

et al. 2022

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In nuclear reactor safety research, the countercurrent gas-liquid two-phase flow in the hot leg of a pressurized water reactor (PWR) has attracted considerable attention. Previous work has proven that the algebraic interfacial area density (AIAD) model implemented in ANSYS CFX can effectively capture the gas-liquid interface and avoid the loss of information regarding the interfacial structure, which occurs after phase averaging in the Euler–Euler two-fluid approach. To verify the accuracy of the AIAD module implementation in ANSYS Fluent, the model based on the experimental data from the WENKA facility is validated in this work. The effects of the subgrid wave turbulence model, turbulence damping model, and droplet entrainment model are simultaneously investigated, which have been shown to be important in the previous work with CFX. The results show that the simulations are considerably and significantly deviate from the experiments when the turbulence damping is not considered. The free surface modeling of two-phase flow can be optimized by using the droplet entrainment model. The consistency between the simulation and experimental results is not enhanced after the subgrid wave turbulence model is adopted. Further investigations regarding the implementation of the subgrid wave turbulence model are necessary.

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CFD evaluations on bundle effects for steam condensation in the presence of air under natural convection conditions

Cited by 26 publications

References 19 publications

Development of a Condensation Model and a New Design of a Condensation Hood—Numerical and Experimental Study

Development of a Condensation Model and a New Design of a Condensation Hood—Numerical and Experimental Study

New Procedure for Thermal Assessment of an Air Cooled Condenser Coupled to Biomass Power Plant

Numerical modeling of horizontal stratified two-phase flows using the AIAD model

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