CFD Simulation of Passive Containment Cooling System in Hot Leg SB-LOCA for 1000MW PWR

2017 ◽  
Author(s):  
Jingya Li ◽  
Xiaoying Zhang
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Cfd Simulation ◽  
Driving Forces ◽  
Cooling System ◽  
Large Mass ◽  
Internal Cooling ◽  
Vapor Injection ◽  
The Difference

The passive cooling system (PCCS) for reactor containment is a security system that can be used to cool the atmosphere and reduce pressure inside of containment in case of temperature and pressure increase caused by vapor injection, which requires no external power because it works only with natural forces. However, as the driving forces from natural physical phenomena are of low amplitude, uncertainties and instabilities in the physical process can cause failure of the system. This article aims to establish a CFD simulation model for the Passive Containment Cooling System of 1000MW PWR using Code_Saturne and FLUENT software. The comparison of 4 different models based respectively on mixture model, COPAIN test, Uchida correlation and Chilton-Colburn analogy which simulate the condensing effect and the improvement of source code are based on a 3D simulation of PCCS system. To simulate the thermal-hydraulic condition in the containment after LOCA accident caused by a double-ended main pipe rupture, a high temperature vapor with the given mass flow rate are supposed to be the source of energy and mass into containment. Meanwhile the surface of three condensing island applies the wall condensation model. The simulation results show similar transient process obtained with the 4 models, while the difference between the transient simulation and the steady-state analysis of three models is less than 3%. The large mass flow rate of water loss status inside the containment cause a high flow rate of vapor which could be uniformly mixed with air in a short time. For the self-condensing efficiency of 3 groups of PCCS system, the non-centrosymmetric injection position resulting that the condensing efficiency is slightly higher for the two heat exchanger groups nearby. During the first 2400s of simulation time, more than 75.69% of the vapor is condensed, indicating that for the occurrence of condensation at the wall mainly driven by natural convection, the effect of thermodynamic siphon could improve the flow of gas mixture inside the tubes when the velocity of mixture is not large enough, so that the vapor could smoothly enter the tube and reach the internal cooling surface then to be condensed. Besides, PCCS ensure the containment internal pressure maintained below 2 bar and the temperature maintained below 380K during 3600s.

scholarly journals Cooling Performance Enhancement of Air-Cooled Condensers by Guiding Air Flow

Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3503
Author(s):  
Huang ◽  
Chen ◽  
Yang ◽  
Du ◽  
Yang
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Dissipation ◽  
Performance Enhancement ◽  
Cooling System ◽  
Wind Effects ◽  
Cooling Performance ◽  
Air Cooled Condensers ◽  
Arc Shape

Adverse wind effects on the thermo-flow performances of air-cooled condensers (ACCs) can be effectively restrained by wind-proof devices, such as air deflectors. Based on a 2 × 300 MW coal-fired power generation unit, two types (plane and arc) of air deflectors were installed beneath the peripheral fans to improve the ACC’s cooling performance. With and without air deflectors, the air velocity, temperature, and pressure fields near the ACCs were simulated and analyzed in various windy conditions. The total air mass flow rate and unit back pressure were calculated and compared. The results show that, with the guidance of deflectors, reverse flows are obviously suppressed in the upwind condenser cells under windy conditions, which is conducive to an increased mass flow rate and heat dissipation and, subsequently, introduces a favorable thermo-flow performance of the cooling system. When the wind speed increases, the leading flow effect of the air deflectors improves, and improvements in the ACC’s performance in the wind directions of 45° and –45° are more satisfactory. However, hot plume recirculation may impede performance when the wind direction is 0°. For all cases, air deflectors in an arc shape are recommended to restrain the disadvantageous wind effects.

scholarly journals Comparison of Swing and Tilting Check Valves Flowing Compressible Fluids

Micromachines ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 758
Author(s):  
Zhi-xin Gao ◽  
Ping Liu ◽  
Yang Yue ◽  
Jun-ye Li ◽  
Hui Wu
Keyword(s):  
Mach Number ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Check Valve ◽  
Small Mass ◽  
Working Fluid ◽  
Valve Disc ◽  
Valve Opening ◽  
The Difference

Although check valves have attracted a lot of attention, work has rarely been completed done when there is a compressible working fluid. In this paper, the swing check valve and the tilting check valve flowing high-temperature compressible water vapor are compared. The maximum Mach number under small valve openings, the dynamic opening time, and the hydrodynamic moment acting on the valve disc are chosen to evaluate the difference between the two types of check valves. Results show that the maximum Mach number increases with the decrease in the valve opening and the increase in the mass flow rate, and the Mach number and the pressure difference in the tilting check valve are higher. In the swing check valve, the hydrodynamic moment is higher and the valve opening time is shorter. Furthermore, the valve disc is more stable for the swing check valve, and there is a periodical oscillation of the valve disc in the tilting check valve under a small mass flow rate.

A New Concept of Impingement Cooling for Gas Turbine Hot Parts and Its Influence on Plant Performance

2003 ◽  
Author(s):  
B. Facchini ◽  
M. Surace ◽  
S. Zecchi
Keyword(s):  
Gas Turbine ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Power Plants ◽  
Cooling System ◽  
Impinging Jets ◽  
Plant Performance ◽  
Transfer Coefficients ◽  
Impingement Cooling

Significant improvements in gas turbine cooling technology are becoming harder as progress goes over and over. Several impingement cooling solutions have been extensively studied in past literature. An accurate and extensive numerical 1D simulation on a new concept of sequential impingement was performed, showing good results. Instead of having a single impingement plate, we used several perforated plates, connecting the inlet of each one with the outlet of the previous one. Main advantages are: absence of the negative interaction between transverse flow and last rows impinging jets (reduced deflection); better distribution of pressure losses and heat transfer coefficients among the different plates, especially when pressure drops are significant and available coolant mass flow rate is low (lean premixed combustion chamber and LP turbine stages). Practical applications can have a positive influence on both cooled nozzles and combustion chambers, in terms of increased cooling efficiency and coolant mass flow rate reduction. Calculated effects are used to analyze main influences of such a cooling system on global performances of power plants.

Evaluation of Effects of Different Design Parameters on Axial Fan Performance Using CFD

2015 ◽  
Author(s):  
Racheet Matai ◽  
Savas Yavuzkurt
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Cfd Simulation ◽  
Chord Length ◽  
Design Parameters ◽  
Axial Fan ◽  
Blade Length ◽  
Resistor Networks ◽  
Mass Flow Rates

The performance of an industrial fan was simulated using CFD and results were compared with the experimental data. The fan is used to cool a row of resistor networks which dissipate excess energy generated by regenerative power in an inverter application. It has a diameter of 24 inches (0.6096m) and rotates at different speeds ranging from 2500 to 3900 RPM depending on the requirements. CFD simulation results were also verified by simulating performance of the same fan at different speeds and comparing the results with what was expected from fan affinity laws. The CFD results matched almost exactly (with ∼0.2% difference for pressure at a given flow rate) with the performance being predicted by the affinity laws. The effect of variation of different parameters such as the blade length, number of blades, and blade chord length was studied. Increasing the blade length at the same RPM increased the mass flow rate (by ∼17%) for the same pressure. Increasing the chord length while keeping the same number of blades, at a given RPM, made the performance curve (pressure versus flow rate, i.e. PV curve) steeper and blades stalled at a higher mass flow rate (8.77 kg/sec compared to the previous 8.44 kg/sec). For the same total blade surface area, less number of blades with longer chords stalled at lower mass flow rates (9.22 kg/sec for a 33% shorter chord and 36 blades compared to 8.3 kg/sec for the original rotor which had 24 blades).

Numerical Investigation of Shock Effects on Performance and Flow Field in a Transonic Centrifugal Impeller

2016 ◽  
Author(s):  
Huijing Zhao ◽  
Zhiheng Wang ◽  
Hongshi Yu ◽  
Chaoyang Jiang ◽  
Guang Xi
Keyword(s):  
Mass Flow Rate ◽  
Boundary Layers ◽  
Mass Flow ◽  
Flow Rate ◽  
Vortex Breakdown ◽  
Suction Side ◽  
Large Mass ◽  
Tip Clearance ◽  
Centrifugal Impeller ◽  
Lower Efficiency

In transonic centrifugal compressors, the losses and blockage are increased dominantly by the shock, shock/tip leakage vortex (TLV) interaction and shock/boundary layers interaction on the blade suction side. Therefore, a detailed investigation of shock effects is seriously important to improve the aerodynamic performance and extend the stable operating range of a centrifugal compressor. This paper firstly analyzes the shock structures in the transonic impeller at the design and off-design conditions. It is found that the shock structure is three-dimensional and swept along the span, with the shock becoming normal to the shroud near the blade tip. As the mass flow rate decreases, the swept shock moves upstream, and the shock/TLV interaction becomes stronger, inducing the vortex breakdown at the near stall condition. Then a comparative study is conducted on the flow structures in the transonic centrifugal impeller without the tip clearance (OTC impeller). Compared with the impeller with a tip clearance (WTC impeller), the splitter shock strength in the passage between the main blade and splitter is enhanced and the separation caused by the splitter shock /boundary layers interaction is induced, due to the lack of the blockage in the inducer induced by the shock/TLV of main blade interaction in the WTC impeller. Thus, at a large mass flow rate, the efficiency of the OTC impeller is lower than that of the WTC impeller because the stronger splitter shock induces larger flow separation in the passages between the main blade and splitter. However, at a small mass flow rate, the WTC impeller has a lower efficiency because the losses in the inducer induced by the interaction between the shock and the TLV of main blade are dominant.

The Sensitivity Analysis of Passive Containment Cooling System During Design Basis Accidents

2012 ◽  
Author(s):  
Zhiwei Zhou ◽  
Yaoli Zhang ◽  
Yanning Yang
Keyword(s):  
Sensitivity Analysis ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Free Space ◽  
Peak Pressure ◽  
Cooling System ◽  
Initial Conditions ◽  
Water Tank ◽  
Design Basis

Containment is the ultimate barrier which protects the radioactive substance from spreading to the atmosphere. Sensitivity analysis on AP1000 containment during postulated design basis accidents (DBAs) was studied by a dedicated analysis code PCCSAP-3D. The code was a three-dimensional thermal-hydraulic program developed to analyze the transient response of the containment during DBAs; and it was validated at a certain extent. Peak pressure and temperature were the most important phenomena during DBAs. The parameters being studied for sensitivity analysis were break source mass flow rate, containment free space, surface area and volume of heat structures, heat capacity of the containment shell, film coverage, cooling water tank mass flow rate and initial conditions. The results showed that break mass flow rate as well as containment free space had the most significant impact on the peak pressure and temperature during DBAs.

Cooling Air Temperature and Mass Flow Rate Control for Hybrid Electric Vehicle Battery Thermal Management

2014 ◽  
Author(s):  
Xinran (William) Tao ◽  
John Wagner
Keyword(s):  
Mass Flow Rate ◽  
Thermal Management ◽  
Air Temperature ◽  
Mass Flow ◽  
Flow Rate ◽  
Cooling System ◽  
Battery Thermal Management ◽  
Thermal Management System ◽  
Battery Thermal Management System ◽  
Cooling Air

Lithium-Ion (Li-ion) batteries are widely used in electric and hybrid electric vehicles for energy storage. However, a Li-ion battery’s lifespan and performance is reduced if it’s overheated during operation. To maintain the battery’s temperature below established thresholds, the heat generated during charge/discharge must be removed and this requires an effective cooling system. This paper introduces a battery thermal management system (BTMS) based on a dynamic thermal-electric model of a cylindrical battery. The heat generation rate estimated by this model helps to actively control the air mass flow rate. A nonlinear back-stepping controller and a linear optimal controller are developed to identify the ideal cooling air temperature which stabilizes the battery core temperature. The simulation of two different operating scenarios and three control strategies has been conducted. Simulation results indicate that the proposed controllers can stabilize the battery core temperature with peak tracking errors smaller than 2.4°C by regulating the cooling air temperature and mass flow rate. Overall the controllers developed for the battery thermal management system show improvements in both temperature tracking and cooling system power conservation, in comparison to the classical controller. The next step in this study is to integrate these elements into a holistic cooling configuration with AC system compressor control to minimize the cooling power consumption.

CFD Simulation of Gas Distributor with Two Chambers

2014 ◽  
Vol 989-994 ◽  
pp. 2264-2267
Author(s):  
Dong Fang Zhao ◽  
Feng Guo Liu
Keyword(s):  
Natural Gas ◽  
Mass Flow Rate ◽  
Turbulence Model ◽  
Mass Flow ◽  
Flow Rate ◽  
Cfd Simulation ◽  
Second Order ◽  
Gas Distributor ◽  
New Type ◽  
Simulation Results

This paper investigated a new type of gas distributor with two chambers by CFD software. The distributor has a natural gas inlet and nine nozzle outlets. For the investigation of this project, the mass flow rate of the distributor was analyzed in this paper to provide a way to optimize the structure of distributor. The N-S equations approached with the RNG k-ε turbulence model and the discretization were employed second order upwind. The simulation results will provide a number of useful suggestions and references for the further design.

Modeling on the Effect of Imbalance Burner Pressure and Mass Flow Rate in a Full-Scale Gas Fired Industrial Boiler

2003 ◽  
Author(s):  
Hasril Hasini ◽  
Mohd. Zamri Yusoff ◽  
Kamsani Abdul Majid ◽  
Mohd. Rizal Ramli ◽  
Hamdan Hassan ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Flow Pattern ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Cfd Simulation ◽  
Combustion Process ◽  
General Purpose ◽  
Anticlockwise Direction ◽  
Industrial Boiler

CFD simulation of the combustion process in a 120MW gas fired industrial boiler has been performed, with focus on the flow pattern and temperature distribution at the reheater section in the furnace. The modeling was done using general-purpose CFD software, CFD-ACE+ developed by CFD Research Corporation. The effect of imbalance burner pressure is simulated by varying the mass flow rate of fuel (natural gas) injected at each burner. The simulation result shows good qualitative agreement with practical observation. The flow in the furnace is highly swirling with intense mixing and follows a helical pattern in an anticlockwise direction. Temperature distribution prior to entry to the reheater is significantly higher on the right side of the reheater. As a conclusion, the imbalance nozzles pressure creates uneven mass flow rate of air and fuel, which results in asymmetric flow pattern and temperature distribution at the reheater section.

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