Numerical Simulation on Primary Side of AP1000 Steam Generator by Porous Media Model

2018 ◽  
Author(s):  
Hu Li-qiang
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Heat Source ◽  
Steam Generator ◽  
Source Function ◽  
Porous Media Flow ◽  
Flow And Heat Transfer ◽  
Porous Media Model ◽  
Tube Bundles ◽  
Geometry Simplification

This paper employed porous media model to simplify the U-tube bundles on primary side of AP1000 steam generator. The simplified model kept the geometry of the U type tube bundles that have 150mm in height in support plate, and simplified the other part in porous media. Flow resistance was computed by Darcy’s law. Heat sources were modeled in two different ways: an average heat source function and a distributive heat source function that couples the heat transfer between the primary and the second sides. It is concluded that the geometry simplification and porous model are appropriate and accurate to describe and predict the characteristics of flow and heat transfer of the primary side well of the U-tube bundles in the steam generator.

CFD Simulations of Heat Recovery Steam Generators Including Tube Banks

2014 ◽  
Author(s):  
Iván F. Galindo-García ◽  
Ana K. Vázquez-Barragán ◽  
Miguel Rossano-Román
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Heat Recovery ◽  
Steam Generators ◽  
Cfd Simulations ◽  
Length Scales ◽  
Flow And Heat Transfer ◽  
Porous Media Model ◽  
Realistic Representation ◽  
Tube Banks

CFD (Computational Fluids Dynamics) simulations of HRSGs (Heat Recovery Steam Generators) can improve and optimize the performance of combined cycle power plants. For example CFD results can help to analyze the effect that different working conditions such as changes in power or fuel quality can have on the uniformity of the flow. A uniform flow is important because the tubes inside the HRSG are more susceptible to corrosion and rupture when the flow distribution is strongly nonuniform. An accurate modeling of the flow and heat transfer characteristics is paramount in order to obtain a realistic representation of the process. However, a big problem in CFD modeling of HRSGs, or any equipment with tube-and-shell heat exchangers, is the different length scales of the equipment, which vary from a few centimeters for the tubes diameter to tens of meters for the HRSG vertical height. The problem is that these different length scales would require a very large computational mesh and consequently a very expensive simulation. To overcome this problem, a common approach in CFD simulations of HRSG has been to model the tube banks following a porous media approach, where the tubes are represented by a volume with a porosity factor which gives the volume fraction of fluid within the porous region. Using this model a pressure drop and the total heat absorbed due to the presence of the solid tubes is calculated. However, due to the recent advances and relatively lower prices of computer equipment it is now possible in a relatively economical way to explicitly include the tube banks in the CFD models of HRSGs. In this study a CFD model of a HRSG is presented where the tube banks are included in the geometric model. Results using this model show the fluid flow and heat transfer between the numerous tubes. A further advantage, in contrast to the porous media model, is that the flow inside the tubes is also modeled which gives a more realistic representation of the phenomena inside the tubes.

Three-Dimensional Steady Simulation on Two-Phase Flow in Secondary Side of Steam Generator

2013 ◽  
Author(s):  
Tenglong Cong ◽  
Wenxi Tian ◽  
Guanghui Su ◽  
Suizheng Qiu
Keyword(s):  
Heat Transfer ◽  
Energy Source ◽  
Porous Media ◽  
Steam Generator ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Flow Induced Vibration ◽  
Two Phase ◽  
Porous Media Model ◽  
Secondary Side

Steam generator (SG), as the primary-to-secondary heat exchanger and pressure boundary of primary loop, should be integrated and performs well in heat transfer ability. Flow characteristics of the secondary side fluid of SG are essential to analyze U-tube wastage caused by the flow-induced vibration and thermal stress. In this paper, secondary side two-phase flow was simulated based on the porous media model. Additional momentum and energy source terms were appended to the momentum and energy equations of porous media region, respectively. The additional momentum source contained the resistances of downcomer, tube bundle, support plate and separator. The additional energy source included the heat transfer from primary side to secondary side fluid. Solving the control equations by ANSYS FLUENT solver yielded the distributions of velocity, temperature, pressure, density and quality, which can be used in the analysis of flow-induced vibration and separator.

NON-DARCY FLUID FLOW AND HEAT TRANSFER IN CONDUITS FITTED WITH POROUS MEDIA

2015 ◽  
Vol 18 (4) ◽  
pp. 449-453 ◽  
Author(s):  
Abdulmajeed A. Mohamad ◽  
Jamel Orfi ◽  
H. Al-Ansary
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Fluid Flow ◽  
Flow And Heat Transfer

Unsteady and porous media flow of reactive non-Newtonian fluids subjected to buoyancy and suction/injection

2015 ◽  
Vol 25 (7) ◽  
pp. 1682-1704 ◽  
Author(s):  
Tirivanhu Chinyoka ◽  
Daniel Oluwole Makinde
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Boundary Conditions ◽  
Flow Velocity ◽  
Flow System ◽  
Finite Difference Methods ◽  
Porous Media Flow ◽  
Convective Boundary Conditions ◽  
Convective Boundary ◽  
Content Type

Purpose – The purpose of this paper is to examine the unsteady pressure-driven flow of a reactive third-grade non-Newtonian fluid in a channel filled with a porous medium. The flow is subjected to buoyancy, suction/injection asymmetrical and convective boundary conditions. Design/methodology/approach – The authors assume that exothermic chemical reactions take place within the flow system and that the asymmetric convective heat exchange with the ambient at the surfaces follow Newton’s law of cooling. The authors also assume unidirectional suction injection flow of uniform strength across the channel. The flow system is modeled via coupled non-linear partial differential equations derived from conservation laws of physics. The flow velocity and temperature are obtained by solving the governing equations numerically using semi-implicit finite difference methods. Findings – The authors present the results graphically and draw qualitative and quantitative observations and conclusions with respect to various parameters embedded in the problem. In particular the authors make observations regarding the effects of bouyancy, convective boundary conditions, suction/injection, non-Newtonian character and reaction strength on the flow velocity, temperature, wall shear stress and wall heat transfer. Originality/value – The combined fluid dynamical, porous media and heat transfer effects investigated in this paper have to the authors’ knowledge not been studied. Such fluid dynamical problems find important application in petroleum recovery.

Sign in / Sign up

Export Citation Format

Share Document