scholarly journals Structural Analysis of a Direct Heated Tubular Solar Receiver for Supercritical CO2 Brayton Cycle

2015 ◽  
Author(s):  
Jesus D. Ortega ◽  
Joshua M. Christian ◽  
Clifford K. Ho
Keyword(s):  
Thermal Stresses ◽  
Structural Model ◽  
Structural Integrity ◽  
Permanent Deformation ◽  
Creep Model ◽  
Outlet Temperature ◽  
Ansys Fluent ◽  
Future Design ◽  
Pressure Load ◽  
Solar Receiver

Closed-loop super-critical carbon dioxide (sCO2) Brayton cycles are being evaluated in combination with concentrating solar power to provide higher thermal-to-electric conversion efficiencies relative to conventional steam Rankine cycles. However, high temperatures (650–700°C) and pressures (20–25 MPa) are required in the solar receiver. In this study, an extensive material review was performed along with a tube size optimization following the ASME Boiler and Pressure Vessel Code and B31.1 and B313.3 codes respectively. Subsequently, a thermal-structural model was developed using ANSYS Fluent and Structural to design and analyze the tubular receiver that could provide the heat input for a ∼2 MWth plant. The receiver will be required to provide an outlet temperature of 650°C (at 25 MPa) or 700°C (at 20 MPa). The induced thermal stresses were applied using a temperature gradient throughout the tube while a constant pressure load was applied on the inner wall. The resulting stresses have been validated analytically using constant surface temperatures. The cyclic loading analysis was performed using the Larson-Miller creep model in nCode Design Life to define the structural integrity of the receiver over the desired lifetime of ∼10,000 cycles. The results have shown that the stresses induced by the thermal and pressure load can be withstood by the tubes selected. The creep-fatigue analysis displayed the damage accumulation due to the cycling and the permanent deformation of the tubes. Nonetheless, they are able to support the required lifetime. As a result, a complete model to verify the structural integrity and thermal performance of a high temperature and pressure receiver has been developed. This work will serve as reference for future design and evaluation of future direct and indirect tubular receivers.

Coupled Fluid Flow and Radiation Modeling of a Cylindrical Small Particle Solar Receiver

2012 ◽  
Author(s):  
Adam Crocker ◽  
Fletcher Miller
Keyword(s):  
Cylinder Wall ◽  
Outlet Temperature ◽  
Gas Temperature ◽  
Dynamics Modeling ◽  
Ansys Fluent ◽  
Data Output ◽  
Gaussian Fit ◽  
Radiation Modeling ◽  
Solar Receiver ◽  
Initial Results

This research expands on previous work by coupling the in-house Monte Carlo Ray Trace (MCRT) radiation model with the more sophisticated fluid dynamics modeling capabilities of ANSYS FLUENT. This allows for the inclusion of more realistic inlet and outlet geometries in the receiver, as well as a turbulence model and much finer grid sizing. Taken together, these features give a more complete picture of the heat transfer, mixing, and temperature profiles within the receiver than previous models. This flow solution is coupled to the MCRT code, by using the in-house MCRT radiation solver to provide the source term of the energy equation. The temperature data output from FLUENT is then fed back into the FORTRAN MCRT code, via a User Defined Function written in C#, and the two models iterate until convergence. The solar input has been modified from the previous model to provide a Gaussian fit to a calculated flux distribution, which is more realistic than a uniform flux. Initial results for a 5 MW solar input agree with the trend identified in Ruther’s work regarding the influence of particle mass loading on heating in the receiver. The maximum outlet temperature reached is 1430K, which is on target for driving a Brayton cycle gas turbine. Cylinder wall temperatures are consistently below those of the gas boundary layer, and significantly below the maximum gas temperature in the receiver cavity.

scholarly journals Aiming Strategy on a Prototype-Scale Solar Receiver: Coupling of Tabu Search, Ray-Tracing and Thermal Models

2021 ◽  
Vol 13 (7) ◽  
pp. 3920
Author(s):  
Benjamin Grange ◽  
Gilles Flamant
Keyword(s):  
Tabu Search ◽  
Ray Tracing ◽  
Wall Temperature ◽  
Gradual Increase ◽  
Particle Temperature ◽  
Outlet Temperature ◽  
Operation Conditions ◽  
Start Up ◽  
Fluidized Particle ◽  
Solar Receiver

An aiming point strategy applied to a prototype-scale power tower is analyzed in this paper to define the operation conditions and to preserve the lifetime of the solar receiver developed in the framework of the Next-commercial solar power (CSP) H2020 project. This innovative solar receiver involves the fluidized particle-in-tube concept. The aiming solution is compared to the case without the aiming strategy. Due to the complex tubular geometry of the receiver, results of the Tabu search for the aiming point strategy are combined with a ray-tracing software, and these results are then coupled with a simplified thermal model of the receiver to evaluate its performance. Daily and hourly aiming strategies are compared, and different objective normalized flux distributions are applied to quantify their influence on the receiver wall temperature distribution, thermal efficiency and particle outlet temperature. A gradual increase in the solar incident power on the receiver is analyzed in order to keep a uniform outlet particle temperature during the start-up. Results show that a tradeoff must be respected between wall temperature and particle outlet temperature.

Structural Integrity Assessment of Free-Fall Lifeboats by Combining Fast Monte-Carlo Simulations With CFD by Means of Proxy Load Variables

2016 ◽  
Author(s):  
Sébastien Fouques ◽  
Ole Andreas Hermundstad
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Structural Integrity ◽  
Free Fall ◽  
Integrity Assessment ◽  
Proxy Variables ◽  
Pressure Load ◽  
Calm Water ◽  
Measured Pressure

The paper is concerned with the launch of free-fall lifeboats (FFL). It proposes a method that complies with the DNV-OS-E406 standard in order to select characteristic launches from Monte Carlo simulations for further structural load assessment with CFD and FEM. Proxy variables derived from kinematic parameters and aiming at predicting pressure load indicators are computed with the VARUNA launch simulator developed by MARINTEK. The statistical distributions of the proxy variables obtained from the Monte Carlo simulations are used to identify critical scenarios, and characteristic launches can then be selected from a chosen probability level. The feasibility of the proposed method is documented in the paper for several types of pressure loads. Existing model test data from various FFL-launch campaigns in calm water and in waves are used to compute the proxy variables as it would be done in the VARUNA simulator. Scatter diagrams showing the correlation with actual measured pressure load indicators are then established to assess the quality of the chosen proxy variables.

scholarly journals Effect of Rubberized Bitumen Blending Methods on Permanent Deformation of SMA Rubberized Asphalt Mixtures

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Herda Yati Katman ◽  
Mohd Rasdan Ibrahim ◽  
Mohamed Rehan Karim ◽  
Suhana Koting ◽  
Nuha Salim Mashaan
Keyword(s):  
Creep Behaviour ◽  
Permanent Deformation ◽  
Asphalt Mixtures ◽  
Creep Model ◽  
Materials Testing ◽  
Wet Process ◽  
Test Conditions ◽  
Dynamic Creep ◽  
Different Temperatures ◽  
Stone Mastic Asphalt

This study aims at comparing the permanent deformation of Stone Mastic Asphalt (SMA) rubberized asphalt mixtures produced by the wet process. In this study, rubberized binders were prepared using two different blending methods, namely, continuous blend and terminal blend. To study the creep behaviour of control and rubberized asphalt mixtures, the dynamic creep test was performed using Universal Materials Testing Apparatus (UMATTA) at different temperatures and stress levels. Zhou three-stage creep model was utilized to evaluate the deformation characteristics of the mixtures. In all test conditions, the highest resistance to permanent deformation is showed by the rubberized mixtures produced with continuous blend binders. This study also reveals that the permanent deformation of rubberized mixtures cannot be predicted based on the characteristics of the rubberized binders.

Heat Flux Distribution Over a Solar Central Receiver Using an Aiming Strategy Based on a Conventional Closed Control Loop

2017 ◽  
Author(s):  
Jesús García ◽  
Yen Chean Soo Too ◽  
Ricardo Vasquez Padilla ◽  
Rodrigo Barraza Vicencio ◽  
Andrew Beath ◽  
...  
Keyword(s):  
Heat Flux ◽  
Flux Distribution ◽  
Thermal Stresses ◽  
Control Strategies ◽  
Multiple Input Multiple Output ◽  
Control Loop ◽  
Heat Flux Distribution ◽  
Input Multiple Output ◽  
Solar Receiver ◽  
Solar Field

Solar thermal towers are a maturing technology that have the potential to supply a significant part of energy requirements of the future. One of the issues that needs careful attention is the heat flux distribution over the central receiver’s surface. It is imperative to maintain receiver’s thermal stresses below the material limits. Therefore, an adequate aiming strategy for each mirror is crucial. Due to the large number of mirrors present in a solar field, most aiming strategies work using a data base that establishes an aiming point for each mirror depending on the relative position of the sun and heat flux models. This paper proposes a multiple-input multiple-output (MIMO) closed control loop based on a methodology that allows using conventional control strategies such as those based on Proportional Integral Derivative (PID) controllers. Results indicate that even this basic control loop can successfully distribute heat flux on the solar receiver.

Analysis of the Leakage-Flow-Induced Vibration of a Slip Joint in a Jet Pump of a Boiling Water Reactor

2019 ◽  
Vol 390 ◽  
pp. 23-31 ◽  
Author(s):  
J. Cruz Castro ◽  
E. Hernández Palafox ◽  
I.A. Alarcón Sánchez ◽  
Luis H. Hernández-Gómez ◽  
Pablo Ruiz-López ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Natural Frequencies ◽  
Excitation Frequency ◽  
Vibration Modes ◽  
The Finite Element Method ◽  
Jet Pump ◽  
Flow Induced Vibration ◽  
Ansys Fluent ◽  
Pump Assembly ◽  
Fourth Mode

The purpose of this analysis is to evaluate the structural integrity of the jet pump assembly of a BWR during the performance of its operational and safety functions. The natural frequencies and vibration modes of the jet pump assembly immersed in water were determined. It was observed that the fourth mode shape was torsional, and its associated resonance frequency was 41.82 Hz. Also, the vibration induced by the flow in the leakage of the slip joint was analyzed with an axisymmetric model. The gap of the slip joint was varied from 0.2 mm until 0.65bmm. A gap between 0.6 and 0.64, would cause flow-induced vibration because this excitation frequency matches with the fourth natural frequency of the jet pump assembly. The above was carried out using computational fluid dynamics, as well as the finite element method, with ANSYS Structural and ANSYS Fluent codes.

Flow Field Simulation in Water Washing Tank of Explosion-Proof Diesel

2014 ◽  
Vol 989-994 ◽  
pp. 3456-3459
Author(s):  
Ri Sheng Long ◽  
Zi Sheng Lian ◽  
Shao Ni Sun ◽  
Qi Liang Wang
Keyword(s):  
Flow Field ◽  
Flow Condition ◽  
Gas Flow ◽  
Outlet Temperature ◽  
Flow Field Simulation ◽  
Design And Optimization ◽  
Waste Gas ◽  
Future Design ◽  
Water Washing ◽  
Field Simulation

In order to improve the cooling & purifying effect of exhaust, reducing the water-jetting phenomenon during working time, the waste-gas flow field simulation in water-washing tank of Explosion-Proof Diesel (EPD) was conducted through ANSYSCFX/Fluent. The results revealed the inner flow condition and outlet temperature of emissions in water-washing tank. It provided a reference for the future design and optimization of the water-washing tank of EPD.

Conjugate Heat Transfer Analysis of a Small Annular Combustor With Centrifugal Fuel Injection System

2019 ◽  
Author(s):  
Rampada Rana ◽  
Alosri Prajwal ◽  
Gullapalli Sivaramakrishna ◽  
Raju Dharappa Navindgi ◽  
Nagalingam Muthuveerappan
Keyword(s):  
Structural Integrity ◽  
Fuel Injection ◽  
Operating Conditions ◽  
Heat Transfer Analysis ◽  
Injection System ◽  
Maximum Temperature ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Ansys Fluent ◽  
Annular Combustor

Abstract Over the years, the requirements of higher specific thrust and lower specific fuel consumption have been necessitating a continual increase in the maximum temperature and pressure in gas turbine engines. However, such an increase has a direct impact on the structural integrity of various modules of the engine; combustor being one of the severely affected modules. This makes the combustor designer’s task of achieving the targeted life of liner, the hottest component of combustor, a challenging one. Estimation of liner metal temperature, thereby arriving at the combustor life, is an essential part of the design process. In the present study, CHT analysis of a radial annular combustor has been carried out. RANS based analysis of a sector combustor with periodicity in flow and geometry has been performed at realistic engine operating conditions using ANSYS Fluent. Predicted liner metal temperatures have been compared with the measured data and a close agreement has been noted between them, the maximum variation being ± 10%.

Analysis of Thermal Stratification and Fatigue Stress for Pressurizer Surge Line

2010 ◽  
Author(s):  
Xiaofei Yu ◽  
Yixiong Zhang
Keyword(s):  
Cross Section ◽  
Thermal Stratification ◽  
Thermal Stresses ◽  
Structural Integrity ◽  
Bending Moments ◽  
One Dimensional ◽  
Pipe System ◽  
Pipe Cross Section ◽  
Fatigue Stress ◽  
Surge Line

Thermal stratification of pressurizer surge line induced by the inside fluid brings on global bending moments, local thermal stresses, unexpected displacements and support loadings of the pipe system. In order to confirm the structural integrity of pressurizer surge line affected by thermal stratification, this paper theoretically establishes thermal stratified transient and studies the calculation method of thermal stratified stress. A costly three-dimensional computation is simplified into a combined 1D/2D technique. This technique uses a pipe cross-section for computation of local thermal stresses and represents the whole surge line with one-dimensional pipe elements. The 2D pipe cross-section model is used to compute elastic thermal stresses in plane strain condition. Symmetry allows half the cross-section to be considered. The one-dimensional pipe elements model gives the global bending moments including effects of usual thermal expansion and thermal stratification of each model nodes. This combined 1D/2D technique has been developed and implemented to analyze the thermal stratification and fatigue stress of pressurize surge line in this paper, using computer codes SYSTUS and ROCOCO. According to the mechanical analysis results of stratification, the maximum stress and cumulative usage factor are obtained. The stress and fatigue intensity of the surge line tallies with the correlative criterion.

The Analysis of Heat Transfer and Thermal Stresses in Thermal Barrier Coatings under Exploitation

2012 ◽  
Vol 326-328 ◽  
pp. 530-535 ◽  
Author(s):  
Tomasz Sadowski ◽  
Przemysław Golewski
Keyword(s):  
Thermal Stresses ◽  
Turbine Blades ◽  
Thermal Barrier ◽  
Internal Cooling ◽  
Ansys Fluent ◽  
Combustion Gases ◽  
Barrier Coating ◽  
Working Medium ◽  
Aero Engines ◽  
Abaqus Code

Effectiveness of internal combustion turbines in aero-engines is limited by comparatively low temperature of exhaust gas at the entry to turbine of the engine. A thermal efficiency and other capacities of turbine strongly depend on the ratio of the highest to the lowest temperature of a working medium. Continuous endeavour to increase the thermal resistance of engine elements requires, apart from laboratory investigations, also numerical studies in 3D of different aero-engine parts. In the present work, the effectiveness of the protection of turbine blades by thermal barrier coating and internal cooling under thermal shock cooling was analysed numerically using the ABAQUS code. The phenomenon of heating the blade from temperature of combustion gases was studied. This investigation was preceded by the CFD analysis in the ANSYS Fluent program which allows for calculation of the temperature of combustion gases. The analysis was conducted for different levels of the shock temperature, different thickness of applied TBC, produced from different kinds of materials.

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