Thermal Hydraulic Studies on Helical Coil Steam Generator by CFD

2011 ◽  
Author(s):  
Sooyun Joh
Keyword(s):  
Heat Transfer ◽  
Steam Generator ◽  
Nuclear Reactor ◽  
Complex Geometry ◽  
Transport Model ◽  
Cfd Modeling ◽  
Helical Coil ◽  
Power Module ◽  
Flux Boundary Condition ◽  
Nuclear Core

NuScale Power, Inc. is commercializing a 45 Megawatt electric light water nuclear reactor NuScale Power Module (NPM). Each NPM includes a containment vessel, a reactor vessel, a nuclear reactor core, an integral steam generator, and an integral pressurizer. The NuScale Power Module is cooled by natural circulation. The primary coolant in the Reactor Pressure Vessel is heated in the nuclear core, it rises through a central riser, it spills over and encounters the helical coil steam generator, it is cooled as steam is generated inside the steam generator, and it is again heated in the nuclear core. The Steam Generator also must be designed to provide adequate heat transfer, to allow adequate primary reactor coolant flow, and to provide adequate steam flow to produce the required power output. This paper presents the CFD results that describe the transport phenomena on the heat transfer and fluid flow dynamics in helical coil steam generator tubes. The ultimate goal of the CFD modeling is to predict the steam outlet conditions associated with the chosen helical coil tube geometries, solving the primary and secondary flow region together coupled with the helical coil tube. However, current studies are focused on the primary side with the heat flux boundary condition assigned on the outer surface of the helical coil steam generator. In this study, the ANSYS CFX v. 12.1 [1] was used to solve the three-dimensional mass, momentum and energy equations. The helical coil steam generator has complex geometry and modeling entire geometry requires the enormous memory that is beyond our hardware capability and is not practical. Therefore, geometry was limited to 1 degree of the wedge and 5% of the total length in the middle. Only external flow, single phase flow around the helical coils, is simulated using the standard k-ε model and shear stress transport model. From the results of the numerical simulation, the pressure drop and temperature profiles were determined. It is important to understand thermal hydraulic phenomena for the design and performance prediction of the reactor internal.

Convective Heat Transfer in a Helical Coil Solar Thermal Collector

2010 ◽  
Author(s):  
Allan May ◽  
Tadhg S. O’Donovan
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Three Dimensional ◽  
Solar Thermal ◽  
Helical Coil ◽  
Dean Number ◽  
Flux Boundary Condition ◽  
Uniform Wall ◽  
Flow Variables ◽  
Coil Heat Exchanger

Three dimensional solar concentrators can achieve concentration ratios in excess of 100 and optical efficiencies in excess of 95% throughout the day without the need for tracking. A helical coil heat exchanger has been designed and investigated numerically as the receiver for this solar thermal application. A computational fluid dynamics (CFD) model of a laminar flow in the heat exchanger was developed in ANSYS CFX and a uniform wall flux boundary condition applied to the outer surface. Due to the curvature of the pipe, Dean Vortices were setup within the flow that substantially increased the overall heat transfer to the solar receiver without significantly increasing the pressure drop across the heat exchanger. A full parametric study is conducted to investigate the effects of geometric properties (dimensionless pitch, coil radius etc) and flow variables (Reynolds number, Dean number, Helical number). The variation of the circumferentially averaged heat transfer coefficient with distance along the heat exchanger is reported. It has been shown that the flow is fully developed after approximately 3.5 turns of the heat exchanger coil and will remain stable throughout the remainder of the heat exchanger.

Helical Pitch Optimization of Double-Tube Once-Through Steam Generator

2014 ◽  
Author(s):  
Huawei Fang ◽  
Xinyu Wei ◽  
Shoujun Yan ◽  
Jiashuang Wan ◽  
Fuyu Zhao
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Maximum Principle ◽  
Pressure Drop ◽  
Steam Generator ◽  
Nuclear Reactor ◽  
Axial Direction ◽  
Tube Length ◽  
The Maximum Principle ◽  
Minimum Pressure

Once-Through Steam Generator (OTSG) is widely used in nuclear reactor system due to its advantages of compactness. The heat transfer performance of DOTSG is studied in this paper. In order to minimize the DOTSG volume and reduce the pressure drop of coolant, the pitch of inner helical tube is optimized with Pontryagin Maximum Principle (PMP). The double-tube is divided to three regions according to the coolant phase in secondary side. With given heat transfer load, choosing a combination function of minimum tube length and minimum pressure drop constructed with linear weighted method as objective function, the pitch optimization proceeds from superheated region to boiling region, and then to sub-cooled region in sequence, using Maximum Principle and gradient method. Then the pitch and temperature distribution along the axis is obtained respectively. The results show that the optimal pitch keeps constant along the axial direction in sub-cooled region and superheated region, but varies in boiling region. In boiling region, compared with minimum tube length optimization, the optimal tube length is 6.4% longer while the pressure drop is 36.3% smaller; and compared with minimum pressure drop optimization, the optimal pressure drop is 29.1% larger while the optimal tube length is 4.6% smaller. With the optimal pitch, the temperature distribution is in agreement with the general physic rules, which proves the correctness and the feasibility of the Maximum Principle method used for the structural optimization of DOTSG in this paper.

scholarly journals SIMULATION OF THERMAL PROCESSES OF A NPP STEAM GENERETOR FOR INFORMATION TECHNOLOGY OPTIMIZED CONTROL

2021 ◽  
pp. 56-61
Author(s):  
Olena Nikulina ◽  
Valerii Severyn ◽  
Nina Kotsiuba ◽  
Anton Bubnov
Keyword(s):  
Heat Transfer ◽  
Information Technology ◽  
Differential Equations ◽  
Steam Generator ◽  
Nuclear Power ◽  
Nuclear Reactor ◽  
Feed Water ◽  
Thermal Processes ◽  
State Variables ◽  
System Of Differential Equations

Mathematical models of thermal processes in the form of Cauchy in the state space with relative variables of the steam generator PGV-1000 of the power unit of a nuclear power plant with a nuclear reactor VVER-1000 have been developed for the using of models in information technology for optimizing the control of a steam generator. The working thermal processes in the PGV-1000 steam generator associated with the supply of feed water to it from the water treatment system and the coolant from the nuclear reactor and the removal of vapors to the main steam header are considered. The design diagram of the steam generator is presented, which reflects the working processes in it under the evaporation mirror and above it. On the basis of differential equations of the heat balance of the heat carrier in the steam generator and in the metal heat exchange tubes, the simulation of heat transfer from the heat carrier to the feed water in the steam generator is carried out. The heat transfer model in the form of a linear system of differential equations in relative state variables is developed. The processes of vaporization during heating of feed water by the heat transfer surface are considered. Differential equations of material and heat balances of dynamic processes of vaporization in a steam generator are compiled, which are not equations in the Cauchy form. Transformations of the differential equations of material and heat balances in the steam generator to the Cauchy form are carried out. A nonlinear system of differential equations for the balance of vaporization in relative state variables is obtained. The values of the constant parameters of the models for the steam generator PGV-1000 are calculated. The mathematical model of thermal processes in the PGV-1000 steam generator, which is presented in the form of a system of differential equations and includes the processes of heat transfer and steam generation, will make it possible to identify and optimize the steam generator control system with the help of information optimization technology. Keywords: nuclear power plant, steam generator, thermal processes, mathematical model, differential equations, optimization, control, information technology.

Analysis of coupled flow and heat transfer in primary and secondary sides of helical coil Once-through steam generator

2021 ◽  
Vol 153 ◽  
pp. 108069
Author(s):  
Fayu Liu ◽  
Xiaoying Zhang ◽  
Jiayue Chen ◽  
Huandong Chen ◽  
Yuan Yuan
Keyword(s):  
Heat Transfer ◽  
Steam Generator ◽  
Helical Coil ◽  
Coupled Flow ◽  
Flow And Heat Transfer
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