Experimental And Computational Study Of A Scaled Reactor Cavity Cooling System

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Experimental and Computational Study of a Scaled Reactor Cavity Cooling System

Author : Rodolfo Vaghetto
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (881 download)

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Book Synopsis Experimental and Computational Study of a Scaled Reactor Cavity Cooling System by : Rodolfo Vaghetto

Download or read book Experimental and Computational Study of a Scaled Reactor Cavity Cooling System written by Rodolfo Vaghetto and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Very High Temperature Gas-Cooled Reactor (VHTR) is one of the next generation nuclear reactors designed to achieve high temperatures to support industrial applications and power generation. The Reactor Cavity Cooling System (RCCS) is a passive safety system that will be incorporated in the VTHR, designed to remove the heat from the reactor cavity and maintain the temperature of structures and concrete walls under desired limits during normal operation and accident scenarios. A small scale (1:23) water-cooled experimental facility was scaled, designed, and constructed in order to study the complex thermohydraulic phenomena taking place in the RCCS during steady-state and transient conditions. The facility represents a portion of the reactor vessel with nine stainless steel coolant risers and utilizes water as coolant. The facility was equipped with instrumentation to measure temperatures and flow rates and a general verification was completed during the shakedown. A model of the experimental facility was prepared using RELAP5-3D and simulations were performed to validate the scaling procedure. The overall behavior of the facility met the expectations. The steady-state condition was achieved and the facility capabilities were confirmed to be very promising in performing additional experimental tests, including flow visualization, and produce data for code validation. The experimental data produced during the steady-state run were successfully compared with the simulation results obtained using RELAP5-3D, confirming the capabilities of the system code of simulating the thermal-hydraulic phenomena occurring in the reactor cavity. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/151742

Analysis of the Reactor Cavity Cooling System for Very High Temperature Gas-cooled Reactors Using Computational Fluid Dynamics Tools

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Author : Angelo Frisani
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (747 download)

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Book Synopsis Analysis of the Reactor Cavity Cooling System for Very High Temperature Gas-cooled Reactors Using Computational Fluid Dynamics Tools by : Angelo Frisani

Download or read book Analysis of the Reactor Cavity Cooling System for Very High Temperature Gas-cooled Reactors Using Computational Fluid Dynamics Tools written by Angelo Frisani and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The design of passive heat removal systems is one of the main concerns for the modular Very High Temperature Gas-Cooled Reactors (VHTR) vessel cavity. The Reactor Cavity Cooling System (RCCS) is an important heat removal system in case of accidents. The design and validation of the RCCS is necessary to demonstrate that VHTRs can survive to the postulated accidents. The commercial Computational Fluid Dynamics (CFD) STAR-CCM+/ V3.06.006 code was used for three-dimensional system modeling and analysis of the RCCS. Two models were developed to analyze heat exchange in the RCCS. Both models incorporate a 180 degree section resembling the VHTR RCCS bench table test facility performed at Texas A & M University. All the key features of the experimental facility were taken into account during the numerical simulations. Two cooling fluids (i.e., water and air) were considered to test the capability of maintaining the RCCS concrete walls temperature below design limits. Mesh convergence was achieved with an intensive parametric study of the two different cooling configurations and selected boundary conditions. To test the effect of turbulence modeling on the RCCS heat exchange, predictions using several different turbulence models and near-wall treatments were evaluated and compared. The models considered included the first-moment closure one equation Spalart-Allmaras model, the first-moment closure two-equation k-e and k-w models and the second-moment closure Reynolds Stress Transport (RST) model. For the near wall treatments, the low y+ and the all y+ wall treatments were considered. The two-layer model was also used to investigate the effect of near-wall treatment. The comparison of the experimental data with the simulations showed a satisfactory agreement for the temperature distribution inside the RCCS cavity medium and at the standpipes walls. The tested turbulence models demonstrated that the Realizable k-e model with two-layer all y+ wall treatment performs better than the other k-e models for such a complicated geometry and flow conditions. Results are in satisfactory agreement with the RST simulations and experimental data available. A scaling analysis was developed to address the distortion introduced by the experimental facility and CFD model in simulating the physics inside the RCCS system with respect to the real plant configuration. The scaling analysis demonstrated that both the experimental facility and CFD model give a satisfactory reproduction of the main flow characteristics inside the RCCS cavity region, with convection and radiation heat exchange phenomena being properly scaled from the real plant to the model analyzed.

Reactor Cavity Cooling System Heat Removal Analysis for a High Temperature Gas Cooled Reactor

Author : Hong-Chan Wei
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (489 download)

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Book Synopsis Reactor Cavity Cooling System Heat Removal Analysis for a High Temperature Gas Cooled Reactor by : Hong-Chan Wei

Download or read book Reactor Cavity Cooling System Heat Removal Analysis for a High Temperature Gas Cooled Reactor written by Hong-Chan Wei and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: The HTR-10 is a small high temperature gas-cooled reactor. It is an experimental pebble-bed helium cooled reactor with a maximum power of 10 MW, constructed between 2000 and 2003 in China. The study focuses on the thermal-fluid analysis of the Reactor Cavity Cooling System (RCCS) with water flows up the pipes to cool the containment. Computational fluid dynamics (CFD) is used to study local heat transfer phenomena in the HTR-10 containment. Heat is transferred to the RCCS mainly via radiation, and to a lesser extent via natural convection. CFD allows for detailed modeling of both heat transfer modes. Sensitivity analyses on the computational grid and the physics models are performed to optimize the simulation. This leads to the use of the k-[omega] model for turbulence and Discrete Ordinates model for radiation. A 2D axisymmetric model is developed to simulate two scenarios from the HTR-10 benchmark exercises provided in the IAEA Coordinated Research Program (CRP-3). The first is a heat up experiment at a reactor power of 200 kW. The experiment simulates normal operation at low power and aims at verifying the RCCS heat removal capability under steady-state conditions. The second is a transient depressurized loss of heat sink accident. In this situation, the reactor is assumed to be running initially at full power, and then the temperature of the core barrel rises over the next 40 hours, peaks, and falls over the next 72 hours. Three fluids are modeled: the helium inside the pressure vessel and outside the core vessel, air in the containment, and water in the RCCS. The boundary conditions are a temperature profile on the core barrel and adiabatic conditions on the containment walls. The simulations lead to safe values of temperature for all the reactor components; also, the computed temperatures compare well with previous simulations performed for the CRP-3.

Experimental Investigations in a Reactor Cavity Cooling System with Advanced Instrumentation for the Study of Instabilities, Oscillations, and Transients

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Author : Casey Allen Tompkins
Publisher :
ISBN 13 :
Total Pages : 176 pages
Book Rating : 4.:/5 (1 download)

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Book Synopsis Experimental Investigations in a Reactor Cavity Cooling System with Advanced Instrumentation for the Study of Instabilities, Oscillations, and Transients by : Casey Allen Tompkins

Download or read book Experimental Investigations in a Reactor Cavity Cooling System with Advanced Instrumentation for the Study of Instabilities, Oscillations, and Transients written by Casey Allen Tompkins and published by . This book was released on 2017 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: A research team at University of Wisconsin - Madison designed and constructed a 1/4 height scaled experimental facility to study two-phase natural circulation cooling in a water-based reactor cavity cooling system (WRCCS) for decay heat removal in an advanced high temperature reactor. The facility is capable of natural circulation operation scaled for simulated decay heat removal (up to 28.5kWm−2 (45kW) input power, which is equivalent to 14.25kWm−2 (6.8MW) at full scale) and pressurized up to 2 bar. The UW-WRCCS facility has been used to study instabilities and oscillations observed during natural circulation flow due to evaporation of the water inventory. During two-phase operation, the system exhibits flow oscillations and excursions, which cause thermal oscillations in the structure. This can cause degradation in the mechanical structure at welds and limit heat transfer to the coolant. The facility is equipped with wire mesh sensors (WMS) that enable high-resolution measurements of the void fraction and steam velocities in order to study the instability's and oscillation's growth and decay during transient operation. Multiple perturbations to the system's operating point in pressure and inlet throttling have shown that the oscillatory behavior present under normal two-phase operating conditions can be damped and removed. Furthermore, with steady-state modeling it was discovered that a flow regime transition instability is the primary cause of oscillations in the UW-WRCCS facility under unperturbed conditions and that proper orifice selection can move the system into a stable operating regime.

Computational Fluid Dynamics Analysis of Very High Temperature Gas-Cooled Reactor Cavity Cooling System

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ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (953 download)

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Book Synopsis Computational Fluid Dynamics Analysis of Very High Temperature Gas-Cooled Reactor Cavity Cooling System by :

Download or read book Computational Fluid Dynamics Analysis of Very High Temperature Gas-Cooled Reactor Cavity Cooling System written by and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The design of passive heat removal systems is one of the main concerns for the modular very high temperature gas-cooled reactors (VHTR) vessel cavity. The reactor cavity cooling system (RCCS) is a key heat removal system during normal and off-normal conditions. The design and validation of the RCCS is necessary to demonstrate that VHTRs can survive to the postulated accidents. The computational fluid dynamics (CFD) STAR-CCM+/V3.06.006 code was used for three-dimensional system modeling and analysis of the RCCS. A CFD model was developed to analyze heat exchange in the RCCS. The model incorporates a 180-deg section resembling the VHTR RCCS experimentally reproduced in a laboratory-scale test facility at Texas A & M University. All the key features of the experimental facility were taken into account during the numerical simulations. The objective of the present work was to benchmark CFD tools against experimental data addressing the behavior of the RCCS following accident conditions. Two cooling fluids (i.e., water and air) were considered to test the capability of maintaining the RCCS concrete walls' temperature below design limits. Different temperature profiles at the reactor pressure vessel (RPV) wall obtained from the experimental facility were used as boundary conditions in the numerical analyses to simulate VHTR transient evolution during accident scenarios. Mesh convergence was achieved with an intensive parametric study of the two different cooling configurations and selected boundary conditions. To test the effect of turbulence modeling on the RCCS heat exchange, predictions using several different turbulence models and near-wall treatments were evaluated and compared. The comparison among the different turbulence models analyzed showed satisfactory agreement for the temperature distribution inside the RCCS cavity medium and at the standpipes walls. For such a complicated geometry and flow conditions, the tested turbulence models demonstrated that the realizable k-epsilon model with two-layer all y+ wall treatment performs better than the other k-epsilon and k-omega turbulence models when compared to the experimental results and the Reynolds stress transport turbulence model results. A scaling analysis was developed to address the distortions introduced by the CFD model in simulating the physical phenomena inside the RCCS system with respect to the full plant configuration. The scaling analysis demonstrated that both the experimental facility and the CFD model achieve a satisfactory resemblance of the main flow characteristics inside the RCCS cavity region, and convection and radiation heat exchange phenomena are properly scaled from the actual plant.

Thermal Hydraulic Analysis of an Experimental Reactor Cavity Cooling System with Water

Author :
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ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (864 download)

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Book Synopsis Thermal Hydraulic Analysis of an Experimental Reactor Cavity Cooling System with Water by :

Download or read book Thermal Hydraulic Analysis of an Experimental Reactor Cavity Cooling System with Water written by and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This experimental study investigated the thermal hydraulic behavior and boiling mechanisms present in a scaled reactor cavity cooling system (RCCS). The experimental facility reflects a 1/4 scale model of one conceptual design for decay heat removal in advanced GenIV nuclear reactors. Radiant heaters supply up to 25 kW/m2 onto a three parallel riser tube and cooling panel test section assembly, representative of a 5° sector model of the full scale concept. Derived similarity relations have preserved the thermal hydraulic flow patterns and integral system response, ensuring relevant data and similarity among scales. Attention will first be given to the characterization of design features, form and heat losses, nominal behavior, repeatability, and data uncertainty. Then, tests performed in single-phase have evaluated the steady-state behavior. Following, the transition to saturation and subsequent boiling allowed investigations onto four parametric effects at two-phase flow and will be the primary focus area of remaining analysis. Baseline conditions at two-phase flow were defined by 15.19 kW of heated power and 80% coolant inventory, and resulted in semi-periodic system oscillations by the mechanism of hydrostatic head fluctuations. Void generation was the result of adiabatic expansion of the fluid due to a reduction in hydrostatic head pressure, a phenomena similar to flashing. At higher powers of 17.84 and 20.49 kW, this effect was augmented, creating large flow excursions that followed a smooth and sinusoidal shaped path. Stabilization can occur if the steam outflow condition incorporates a nominal restriction, as it will serve to buffer the short time scale excursions of the gas space pressure and dampen oscillations. The influences of an inlet restriction, imposed by an orifice plate, introduced subcooling boiling within the heated core and resulted in chaotic interactions among the parallel risers. The penultimate parametric examined effects of boil-off and inventory loss, where five different stages of natural circulation flow were identified: single-phase heating, transitional nucleate boiling, hydrostatic head fluctuations, stable two-phase flow, and geysering. Finally, the implementation of the model RCCS to a full scale plant was investigated by a multivariate test simulating an hypothetical accident scenario.

Thermal-Hydraulic Analysis of an Experimental Reactor Cavity Cooling System with Air. Part I

Author :
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ISBN 13 :
Total Pages : 185 pages
Book Rating : 4.:/5 (925 download)

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Book Synopsis Thermal-Hydraulic Analysis of an Experimental Reactor Cavity Cooling System with Air. Part I by :

Download or read book Thermal-Hydraulic Analysis of an Experimental Reactor Cavity Cooling System with Air. Part I written by and published by . This book was released on 2014 with total page 185 pages. Available in PDF, EPUB and Kindle. Book excerpt: This experimental study investigates the thermal hydraulic behavior and the heat removal performance for a scaled Reactor Cavity Cooling System (RCCS) with air. A quarter-scale RCCS facility was designed and built based on a full-scale General Atomics (GA) RCCS design concept for the Modular High Temperature Gas Reactor (MHTGR). The GA RCCS is a passive cooling system that draws in air to use as the cooling fluid to remove heat radiated from the reactor pressure vessel to the air-cooled riser tubes and discharged the heated air into the atmosphere. Scaling laws were used to preserve key aspects and to maintain similarity. The scaled air RCCS facility at UW-Madison is a quarter-scale reduced length experiment housing six riser ducts that represent a 9.5° sector slice of the full-scale GA air RCCS concept. Radiant heaters were used to simulate the heat radiation from the reactor pressure vessel. The maximum power that can be achieved with the radiant heaters is 40 kW with a peak heat flux of 25 kW per meter squared. The quarter-scale RCCS was run under different heat loading cases and operated successfully. Instabilities were observed in some experiments in which one of the two exhaust ducts experienced a flow reversal for a period of time. The data and analysis presented show that the RCCS has promising potential to be a decay heat removal system during an accident scenario.

Experimental and CFD Analysis of Advanced Convective Cooling Systems

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ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (953 download)

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Book Synopsis Experimental and CFD Analysis of Advanced Convective Cooling Systems by :

Download or read book Experimental and CFD Analysis of Advanced Convective Cooling Systems written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this project is to study the fundamental physical phenomena in the reactor cavity cooling system (RCCS) of very high-temperature reactors (VHTRs). One of the primary design objectives is to assure that RCCS acts as an ultimate heat sink capable of maintaining thermal integrity of the fuel, vessel, and equipment within the reactor cavity for the entire spectrum of postulated accident scenarios. Since construction of full-scale experimental test facilities to study these phenomena is impractical, it is logical to expect that computational fluid dynamics (CFD) simulations will play a key role in the RCCS design process. An important question then arises: To what extent are conventional CFD codes able to accurately capture the most important flow phenomena, and how can they be modified to improve their quantitative predictions? Researchers are working to tackle this problem in two ways. First, in the experimental phase, the research team plans to design and construct an innovative platform that will provide a standard test setting for validating CFD codes proposed for the RCCS design. This capability will significantly advance the state of knowledge in both liquid-cooled and gas-cooled (e.g., sodium fast reactor) reactor technology. This work will also extend flow measurements to micro-scale levels not obtainable in large-scale test facilities, thereby revealing previously undetectable phenomena that will complement the existing infrastructure. Second, in the computational phase of this work, numerical simulation of the flow and temperature profiles will be performed using advanced turbulence models to simulate the complex conditions of flows in critical zones of the cavity. These models will be validated and verified so that they can be implemented into commercially available CFD codes. Ultimately, the results of these validation studies can then be used to enable a more accurate design and safety evaluation of systems in actual nuclear power applications (both during normal operation and accident scenarios).

Scaling, Experiments, and Simulations of Condensation Heat Transfer for Advanced Nuclear Reactors Safety

Author : Palash Kumar Bhowmik
Publisher :
ISBN 13 :
Total Pages : 199 pages
Book Rating : 4.:/5 (128 download)

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Book Synopsis Scaling, Experiments, and Simulations of Condensation Heat Transfer for Advanced Nuclear Reactors Safety by : Palash Kumar Bhowmik

Download or read book Scaling, Experiments, and Simulations of Condensation Heat Transfer for Advanced Nuclear Reactors Safety written by Palash Kumar Bhowmik and published by . This book was released on 2021 with total page 199 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The purpose of this research was to perform scaled experiments and simulations to validate computational fluid dynamics (CFD) and empirical models of condensation heat transfer (CHT) for the passive containment cooling system (PCCS) of Small Modular Reactors (SMRs). SMRs are the futuristic candidates for clean, economic, and safe energy generation; however, reactor licensing requires safety system evaluations, such as PCCS. The knowledge in the reviewed relevant literature showed a gap in experimental data for scaling SMR's safety systems and validating computational models. The previously available test data were inconsistent due to unscaled geometric and varying physics conditions. These inconsistencies lead to inadequate test data benchmarking. This study developed three scaled (different diameters) test sections with annular cooling for scale testing and analysis to fill this research gap. First, tests were performed for pure steam and steam with non-condensable gases (NCGs), like nitrogen and helium, at different mass fractions, inlet mass flow rates, and pressure ranges. Second, detailed CFD simulations and validations were performed using STAR-CCM+ software with scaled geometries and experimental parameters (e.g., flow rate, pressure, and steam-NCG mixtures), thus mimicking reactor accident cases. The multi-component gases, multiphase mixtures, and fluid film condensation models were applied, verified, and optimized in the CFD simulations with associated turbulence models. Third, the physics-based and data-driven condensation models and empirical correlations were assessed to quantify the scaling distortions. Finally, the experiments, simulations, and modeling results were evaluated for critical insights into the physics conditions, scaling effects, and multi-component gas mixture parameters. This study supported improvements to nuclear reactor safety systems' modeling capabilities irrespective of size (small or big), and findings were equally applicable to other non-nuclear energy applications"--Abstract, page iii.

CFD Model Development and Validation for High Temperature Gas Cooled Reactor Cavity Cooling System (RCCS) Applications

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ISBN 13 :
Total Pages : 320 pages
Book Rating : 4.:/5 (925 download)

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Book Synopsis CFD Model Development and Validation for High Temperature Gas Cooled Reactor Cavity Cooling System (RCCS) Applications by :

Download or read book CFD Model Development and Validation for High Temperature Gas Cooled Reactor Cavity Cooling System (RCCS) Applications written by and published by . This book was released on 2014 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Reactor Cavity Cooling Systems (RCCS) is a passive safety system that will be incorporated in the VTHR design. The system was designed to remove the heat from the reactor cavity and maintain the temperature of structures and concrete walls under desired limits during normal operation (steady-state) and accident scenarios. A small scale (1:23) water-cooled experimental facility was scaled, designed, and constructed in order to study the complex thermohydraulic phenomena taking place in the RCCS during stead-state and transient conditions. The facility represents a portion of the reactor vessel with nine stainless steel coolant risers and utilizes water as coolant. The facility was equipped with instrumentation to measure temperatures and flow rates and a general verification was completed during the shakedown. A model of the experimental facility was prepared using RELAP5-3D and simulations were performed to validate the scaling procedure. The experimental data produced during the stead-state run were compared with the simulation results obtained using RELAP5-3D. The overall behavior of the facility met the expectations. The facility capabilities were confirmed to be very promising in performing additional experimental tests, including flow visualization, and produce data for code validation.

Thermal Hydraulic Analysis of an Experimental Reactor Cavity Cooling System with Air

Author : Moses A. Muci
Publisher :
ISBN 13 :
Total Pages : 284 pages
Book Rating : 4.:/5 (891 download)

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Book Synopsis Thermal Hydraulic Analysis of an Experimental Reactor Cavity Cooling System with Air by : Moses A. Muci

Download or read book Thermal Hydraulic Analysis of an Experimental Reactor Cavity Cooling System with Air written by Moses A. Muci and published by . This book was released on 2014 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Experimental and Analytic Evaluation of Gas-cooled Reactor Cavity Cooling System Performance

Author : Gang Fu
Publisher :
ISBN 13 :
Total Pages : 598 pages
Book Rating : 4.:/5 (25 download)

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Book Synopsis Experimental and Analytic Evaluation of Gas-cooled Reactor Cavity Cooling System Performance by : Gang Fu

Download or read book Experimental and Analytic Evaluation of Gas-cooled Reactor Cavity Cooling System Performance written by Gang Fu and published by . This book was released on 1991 with total page 598 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Experimental Study of the Thermal-hydraulic Phenomena in the Reactor Cavity Cooling System and Analysis of the Effects of Graphite Dispersion

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Author : Rodolfo Vaghetto
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (82 download)

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Book Synopsis Experimental Study of the Thermal-hydraulic Phenomena in the Reactor Cavity Cooling System and Analysis of the Effects of Graphite Dispersion by : Rodolfo Vaghetto

Download or read book Experimental Study of the Thermal-hydraulic Phenomena in the Reactor Cavity Cooling System and Analysis of the Effects of Graphite Dispersion written by Rodolfo Vaghetto and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental activity was performed to observe and study the effects of graphite dispersion and deposition on thermal hydraulic phenomena in a Reactor Cavity Cooling System (RCCS). The small scale RCCS experimental facility (16.5cm x 16.5cm x 30.4cm) used for this activity represents half of the reactor cavity with an electrically heated vessel. Water flowing through five vertical pipes removes the heat produced in the vessel and releases it in the environment by mixing with cold water in a large tank. PIV technique was used to study the velocity field of the air inside the cavity. A set of 52 thermocouples was installed in the facility to monitor the temperature profiles of the vessel and pipes walls and air. 10g of a fine graphite powder (particle size average 2 [mu]m) were injected into the cavity through a spraying nozzle placed at the bottom of the vessel. Temperatures and air velocity field were recorded and compared with the measurements obtained before the graphite dispersion, showing a decrease of the temperature surfaces which was related to an increase in their emissivity. The results contribute to the understanding of the RCCS capability in case of an accident scenario.

A CFD Design Study of an Air Reactor Cavity Cooling System Using Traditional Thermal Analysis Techniques and Entropy Generation Analysis

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Author : Kurt D. Hamman
Publisher :
ISBN 13 : 9781339321523
Total Pages : 412 pages
Book Rating : 4.3/5 (215 download)

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Book Synopsis A CFD Design Study of an Air Reactor Cavity Cooling System Using Traditional Thermal Analysis Techniques and Entropy Generation Analysis by : Kurt D. Hamman

Download or read book A CFD Design Study of an Air Reactor Cavity Cooling System Using Traditional Thermal Analysis Techniques and Entropy Generation Analysis written by Kurt D. Hamman and published by . This book was released on 2015 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt: Current research in advanced reactor designs has focused on passive safety systems, where in the event of a loss of cooling to the reactor core, excess heat will be removed by a passive safety heat removal system. A safety system is classified as 'passive' because it does not require a pump to circulate the fluid (i.e., forced circulation) or operator action to maintain cooling. The system relies on the natural circulation of a fluid (i.e., fluid density differences and gravity) to transfer the heat. Passive safety system designs include features that enhance natural circulation, such as using smooth pipes, minimizing flow obstructions, and maximizing density differences, which increase fluid velocity and hence the removal of more heat. This research consisted of a CFD study of wall-bounded transitional flows and a passive reactor cavity cooling system. Yet in an effort to better understand fundamental phenomena, relative to the limits of natural circulation turbulence modeling, only forced circulation CFD analyses were performed. The initial phase of this research consisted of two types of CFD studies: 2D entropy generation rate boundary layer analyses of an isothermal transitional fluid flow over a flat plate, and 3D thermal performance analyses of a 1/4-scale experimental air reactor cavity cooling system. The 2D flat plate boundary layer studies were important in that they provided insight into flow features, such as boundary layer development and entropy generation rate, in the 3D RCCS ducts as the air transitions from laminar to turbulent flow. Using the results of the initial study as a baseline, this work analyzed the viscous and thermal boundary layer development, including estimating the entropy generation rate, in the heated duct section of the RCCS, which is characterized by nonuniform flow and heat transfer. A new engineering design process was developed, which incorporates not only traditional heat transfer and fluid flow (HTFF) analysis techniques but entropy generation minimization (EGM) concepts as well. This analysis process was successfully applied to the existing 1/4-scale experimental air RCCS, resulting in the identification of the primary entropy dissipation mechanism and an improved design.

Scaling Approach and Thermal-hydraulic Analysis in the Reactor Cavity Cooling System of a High Temperature Gas-cooled Reactor and Thermal-jet Mixing in a Sodium Fast Reactor

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Author : Olumuyiwa A. Omotowa
Publisher :
ISBN 13 :
Total Pages : 502 pages
Book Rating : 4.:/5 (882 download)

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Book Synopsis Scaling Approach and Thermal-hydraulic Analysis in the Reactor Cavity Cooling System of a High Temperature Gas-cooled Reactor and Thermal-jet Mixing in a Sodium Fast Reactor by : Olumuyiwa A. Omotowa

Download or read book Scaling Approach and Thermal-hydraulic Analysis in the Reactor Cavity Cooling System of a High Temperature Gas-cooled Reactor and Thermal-jet Mixing in a Sodium Fast Reactor written by Olumuyiwa A. Omotowa and published by . This book was released on 2014 with total page 502 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Heat Transfer Simulation of Reactor Cavity Cooling System Experimental Facility Using RELAP5-3D and Generation of View Factors Using MCNP

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Author : Huali Wu
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (873 download)

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Book Synopsis Heat Transfer Simulation of Reactor Cavity Cooling System Experimental Facility Using RELAP5-3D and Generation of View Factors Using MCNP by : Huali Wu

Download or read book Heat Transfer Simulation of Reactor Cavity Cooling System Experimental Facility Using RELAP5-3D and Generation of View Factors Using MCNP written by Huali Wu and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: As one of the most attractive reactor types, the High Temperature Gas-cooled Reactor (HTGR) is designed to be passively safe with the incorporation of Reactor Cavity Cooling System (RCCS). In this paper, a RELAP5-3D simulation model is set up based on the 1/16 scale experimental facility established by Texas A&M University. Also, RELAP5-3D input decks are modified to replicate the experiment procedures and the experimental results are compared with the simulation results. The results show there is a perfect match between experimental and simulation results. Radiation heat transfer dominates in the heat transfer process of high temperature gas-cooled reactor due to its high operation temperature. According to experimental research done with the RCCS facility in Texas A&M University, radiation heat transfer takes up 80% of the total heat transferred to standing pipes. In radiation heat transfer, the important parameters are view factors between surfaces. However, because of the geometrical complexity in the experimental facility, it is hard to use the numerical method or analytical view factor formula to calculate view factors. In this project, MCNP based on the Monte Carlo method is used to generate view factors for RELAP5-3D input. MCNP is powerful in setting up complicated geometry, source definition and tally application. In the end, RCCS geometry is set up using MCNP and view factors are calculated. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/151265

Characterization of the Thermal Hydraulic Behavior of an Experimental Reactor Cavity Cooling System with Water

Author : Michael Joseph Gorman
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (956 download)

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Book Synopsis Characterization of the Thermal Hydraulic Behavior of an Experimental Reactor Cavity Cooling System with Water by : Michael Joseph Gorman

Download or read book Characterization of the Thermal Hydraulic Behavior of an Experimental Reactor Cavity Cooling System with Water written by Michael Joseph Gorman and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An existing experimental Reactor Cavity Cooling System using water as the coolant received extensive instrumentation and control upgrades to allow for a thorough investigation into the single-phase flow behavior of the system under a variety of experimental conditions. Base level conditions used a uniform heat flux at a power level appropriately scaled from a benchmark computer simulation of the Gas Turbine Modular Helium Reactor (GT-MHR) using scaling relationships derived by Argonne National Laboratory. Experiments were setup to gauge the effects of flow throttling, non-uniform heat flux profiles, alternate power levels and alternate coolant inventory levels on the flow distribution in the Cooling Panel, and to investigate the relationships between system variables of applied power, the temperature difference across the Cooling Panel ([delta]T) and flowrate. In addition, a single scoping experiment was executed to observe system performance with coolant at the saturation temperature. The system variables proved to have highly linear relationships amongst each other under all experimental conditions. Flow instabilities were observed in the form of counter-phase sinusoidal oscillations of flowrate and [delta]T, the frequency thereof showed a roughly linear relationship with power. Ultrasonic Velocity Profiling (UVP) was used to determine the flow distribution, which increased at the outlet side of the panel with either increased system flowrate or higher heat flux applied to the outlet side, and vice-versa. The effect caused by flowrate changes was the same whether due to a change in power level or throttling, indicating the fluid's momentum is the driving factor. The phenomenon of sudden, high velocity, short duration flow excursions, called geysering, was observed as the system coolant was brought to saturation. This was caused by the trapping of non-condensable gases in the top horizontal section of the flow loop, which in turn brought the flowrate down considerably, increasing residence time and temperature of the coolant in the Cooling Panel. Subsequent rise of saturated coolant to a higher elevation in the hot leg resulted in flashing of the coolant to steam, whose sudden expansion drove the flow excursion. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/155387