In this paper, a novel nodalized reduced order model (NROM) has been developed to analyze the linear stability in a heated channel using supercritical water (SCW) as a coolant. The presented reduced order model is developed based on the two-phase flow system approach. The model is much simplified, which reduced the requirement of computational efforts and resources. In the heated channel, the SCW’s density shows a dramatic downfall near the pseudo-critical temperature, based on which it has been divided into n number of nodes. The one-dimension partial differentiation conservation equations of energy, mass and momentum are used and have been linearized by a small perturbation applied on its steady-state solution. These PDEs are converted into the corresponding time-dependent, nonlinear ordinary differential equations (ODEs) by using weighted residual method applied under some appropriate assumptions and approximations. These sets of ODEs (n+1 equations) are then solved analytically by using a state space approach to capture the stability boundary (SB) in terms of trans-pseudo-critical phase change number ( N tpc ), pseudo-subcooling number ( N spc ) by applying a constant external pressure drop (Δ P tpc ) condition across the channel. The NROM results are found to be in good agreement with the methodology and have been verified by numerical simulation. To extend this as a nonlinear stability analysis, the different types of the Hopf Bifurcation regime are also reported.

Digital power plant is the theory and method to improve the operating quality of power plant by quantifying, analyzing, controlling and deciding the physical and working objects of power plants in the whole life cycle. Signals and management information of power plants will be digitized, so as to realize information exchange reliably and accurately and large-scale distributed resource sharing based on the network technology. Then optimization decisions and scientific guidance for plant operation will be proposed by intelligent expert system based on the digital resources. Therefore, the foundation of digital power plant is system modeling and performance analysis. However, there are some problems in the process of the modeling performance analysis of digital power plant. For instance, each unit of the system model has different dimensions and different type of mathematical description, and the data or information used for modeling are defined differently and belong to different enterprises, who do not want to share their information. Metamodeling is potential to solve these problems. It defines the specification to describe a unit and the relationship between different elements. Compared with traditional modeling methodologies for thermal systems, metamodeling makes the model more standardized, and the relationship of the model elements is more explicit and better understood by the co-simulation partners. In this paper, the collaborative modeling and simulation platform for digital power plant has been established based on the metamodeling method and the performance of the target plant has been analyzed from different aspects via field data. The metamodeling method consists of three parts: syntax definition, model development and algorithm definition. The result shows that the collaborate modeling and simulation platform can be used to reduce costs, decrease equipment failure rate, and improve plant output, so as to guarantee the safety and increase economics.

Coupling of statistical properties from atomistic simulations to continuum is essential to model many multi-scale phenomena. Often, the system under consideration will be homogeneous in two-dimensions (2-D). But due to the existing coupling methods, the property estimation takes place in three-dimensions (3-D) and then averaged to 2-D, which is computationally expensive due to the 3-D convolutions. A direct 2-D pressure or stress estimation model is lacking in literature. In this work, we develop a direct 2-D pressure field estimation method which is much faster than 3-D methods without losing accuracy. The method is validated with MD simulations on two systems: a liquid film and a cylindrical drop of argon suspended in surrounding vapor. This formulation will enable the study of 2-D fundamental phenomena like passive liquid flows in microlayer, as well as facilitate the coupling of atomistic and continuum simulations with reduced computational cost.

The nozzle block is one of the most important parts of steam turbine. It puts the steam heat energy into kinetic energy and plays a guiding role to the steam flow. The open integral nozzle block is a very unique structure. Due to the restriction of the large steam passage bending degree and the small nozzle mouth, the traditional process is difficult and the production efficiency is low. This paper mainly studies the structure and processing method of a new open integral nozzle block. The difficulties of the manufacturing process are being solved one by one by the way of developing the five-axis NC program, designing the special tooling and making the process technical solution. The process technical solution is to split the whole complex structure into three main parts which are easy to machine. It can easily realize the surface finishing of the steam passage and guarantee the geometric dimension of each steam blade. The surface roughness of the steam passage can reach Ra0.8. The precision requirements for machining and assembling of the open integral nozzle block can be fully met. It has a wide application prospect in promoting the scientific and technological progress of the new structure and the new process.

Effective Plume-Chimney Height (EPCH) was a factor engineers used to design and analyse the performance of natural convection in air-cooled heat exchangers particularly in the event of power outage. To date the number of papers in the open literature presenting data on natural convection performance of air-cooled heat exchangers is scarce. The aim of this study is to corroborate the experimental results and theoretical predictions of Effective Plume-Chimney Height (EPCH) using Computational Fluid Dynamics (CFD) in a laboratory-scale air cooled heat exchanger of 457mm × 457mm face area and an industrial-scale test rig of 2.4m × 6.0m face area forced draft air-cooled heat exchanger comprising of a bundle with 4 rows of annular finned tubes in staggered formation operating under natural convection. The CFD software Phoenics 2015 was employed to simulate the electrically-heated air-cooled heat exchanger fitted with a top screen which was built to study the aerodynamics of natural convection of air-cooled heat exchangers. The CFD geometry arrangement and dimensions were schematic in nature, where errors introduced were considered reasonably negligible. The laboratory-scale exchanger model experimental pressure drop data was found to have an insignificant effective plume-chimney height, as predicted by a theoretical equation. It was found that EPCH values calculated from CFD results agree closely to within −0.11m and +0.06m with both experiments and the theoretical prediction, confirming the same conclusion reached in an earlier report. However, for an industrial-scale test rig (ITR) in forced draft mode of large face dimensions the EPCH had been found to be non-negligible in an earlier work. Significant values of theoretical effective plume-chimney height were inserted in the heat transfer and pressure drop simulation that appeared to yield results that agreed with the experimental heat loads. The CFD simulations on the ITR have confirmed the existence of significant effective plume-chimney heights at more than 100 percent of the bundle depth, or the chimney height. The implication is that a solid-walled chimney can appear to have an efficiency of more than 100 per cent, if cold inflow can be prevented or the penetration to the central core hindered. Since the validation of the existence of EPCH by CFD here has used only a set of data from a single source, it is worthwhile to produce more experimental data and analysis to establish the concept for better predictions of air-cooled heat exchanger natural convection performance.

Renewable energy technologies offer a competitive cost of energy values in large-scale power generations compared with those from traditional energy resources. In 2015, residential and commercial buildings consumed 40% of total US energy consumption. Short and long-term plans have been developed to further employing wind energy technologies for electricity generation. However, there is a significant gap in developing reliable utility-scaled distributed wind energy converters. Employing novel low-cost wind harnessing technologies in these sectors supports the renewable-energy expansion plans. A novel ducted wind turbine technology, called Wind Tower, for capturing wind power is designed and developed in earlier works. In this work, the Wind Tower structural analysis is conducted to obtain insights to the required materials and optimum components’ dimensions at an expanded range of wind flow regimes. A stable and robust design addresses the need for developing an optimum solution to obtain a maximum output power generation at a minimum cost of energy. It will lead to a maximum return on investment. The results demonstrate a superior structural performance of the Wind Tower Technology. It withstands pressure loads from high wind speed when it is installed as a standalone structure.

Stress Concentration Factor (SCF) is significant in machine elements as it gives rise to localised stresses which lead to peak stresses introducing cracks which propagate further and hence the component fails before the desired design life. Turbine blades are subjected to high centrifugal stresses and vibratory stresses in a Gas Engine HP Rotor. The vibratory stresses arise due to air wake flow excitations called Nozzle Passing Frequency (NPF). Hence, Turbomachinery industry calls for an optimum structurally rigid blade root geometry. An optimum blade root was defined, as a root with practical geometry, which when loaded returns the minimum fillet SCF. In the present work an approach has been done for design optimization of fillet stresses at sharp edges of T-root blade, optimization of platform dimensions, shank dimensions, root land dimensions and to ensure that stress distribution is uniformly spread along the filleted width of the root land on both sides of the blade, which otherwise will lead to crack initiation, propagation and hence, fretting failure at blade root lands. This may further lead to blade lift and effect on stage and overall gas engine failure over a period of cycles. Hence, a special attention is made on SCF of the T root -blade which fails and to guarantee for safe and reliable operation under all possible service conditions. Finite Element Analysis (FEA) is used to determine the fillet stresses and Peterson’s SCF chart is effectively utilized to modify the blade root. The root is modified due to the difficulty in manufacturing the butting surface of the tang which grips the blade to the disk crowns having small contact area. The blade height is suitably designed using Campbell diagram by ensuring the working frequency is well within 6e excitations for the specified operating speeds. Hence, increasing the life of the HP compressor blade.

Low flow steam siphon jet pumps are referred to as rate jets, since these pumps have the ability to control flow rates by varying the steam pressure applied to the jet. The jet pump design consists of several components. Steam inlet piping is connected to a steam nozzle that directs steam into the jet body to provide energy to lift a liquid, or feed. Feed is lifted up through the suction lift piping, where the condensing steam forces the liquid into a diffuser and out of the jet discharge piping. Closed form equations cannot model these jets, and commercial computer models to describe jet performance are still in a state of development. In general, experimental data is required to determine the performance characteristics of this type of jet design. Numerous tests were performed on different jet designs to evaluate the effects of motive steam pressures, suction lift, discharge head, jet dimensions, and the specific gravity of the fluid that is lifted and pumped by the jet. Additionally, the system installation significantly affects the performance of siphon jets, and one such installation was studied.

The aim of the present study is to numerically investigate the combustion characteristics of Heavy Fuel Oil (HFO) and NOx emissions inside a calciner used in cement industry. The calciner is a furnace placed before the rotary Kiln its main objectives are the reduction of CO 2 emissions and air pollutions while enhancing the cement quality through separating the calcination and clinkering processes. In order to conduct the present investigations the calciner at CEMEX Egypt Cement Company was considered and real dimensions and operating conditions were applied. The combustion model was based on the conserved scalar (mixture fraction) and prescribed Probability Density Function (PDF) approach. The (RNG) k-ε turbulence model has been used. The HFO droplet trajectories were predicted by solving the momentum equations for the droplets using Lagrangian treatment. The radiation heat transfer equation was solved using P1 method. The formation of thermal NO x from molecular nitrogen was modeled according to the extended Zeldovich mechanism. The effects of varying the burner’s swirl number and viscosity grade on the combustion performance of HFO and the resulting NO x emissions were considered. The burner’s swirl number influences the mixing rate of air and fuel. A small swirl number ≤ 0.6 is not desired as it elongates the flame; increases flue gases temperatures and increases the NOx emissions inside the calciner. A swirl number ≥ 0.6 is found optimal for good combustion characteristics and NOx emissions concentration. Meanwhile, it was found that the HFO viscosity has a significant effect on the injection velocity and must be considered as a function of temperature during the analysis as this will significantly affects the combustion characteristics.

CFD simulation was carried out to corroborate experimental data at fixed heat load of nominally 2.3kW from a natural draft heat exchanger of face dimensions of 0.75m × 0.75m, with or without mitigation of the cold inflow at the chimney exit, where mitigation by installing wire mesh on top of the chimney has been shown by the experiments to enhance air flow rate. A chimney model was simulated at fixed heat loads in a still surrounding at ambient temperature of 30 degree Celsius and atmospheric pressure for two modes: Mode 1 and Mode 0 for with and without a flow resistor (wire mesh) respectively at the top exit. It was found that the simulation could reproduce most of the trends of the experimental data, but had a tendency to magnify the detrimental effects of cold inflow and exaggerate the remedial action of wire mesh in preventing cold inflow, as reflected by the ratio of Mode 1 to Mode 0 air mass flowrate by a factor of up to 2.36, compared to 1.50 in the experimental data. In both simulation and experiment, the average air flow rates obtained at chimney heights of 0.35m, 0.65m, 0.95m and 1.25m, showed progressive increase of air mass flow rate for all cases. Both experimental and simulated heat gain in Mode 0 were more or less constant until the highest chimney height where they showed apparent breakout upwards, whereas in Mode 1 the experimental heat gains gently reduced to a plateau while the simulated heat gains hovered at around 2.3kW. The back calculated values of Mode 0 experimental outlet temperature at between 140 to 240°C raises concern of hotspot in some electronic components by the ineffectiveness of chimney systems without cold inflow mitigation. Further experiments of similar scale with steadier control of heat flux and heating temperature, and simulating with other turbulence models in transient mode will improve understanding in both Mode 0 and Mode 1 of operation.

Microchannel heat sink with its high heat transfer area density and potentially high heat transfer coefficient has been proposed for applications with high heat fluxes. The objective of this study is to investigate single-phase convection in the thermally developing region of a rectangular microchannel. An infrared thermography provides an effective approach for non-intrusive and spatio-temporal measurement of temperature. The entrance region, where the heat transfer coefficient is higher than that of the fully developed region, is of particular interest for microchannel cooling applications. The present study establishes an innovative benchmark experimental measurement uaing an infrared thermography. The experiments are conducted on a rectangular cross-section microchannel made of aluminum alloy 6061 with dimensions 22mm×1.5mm×0.3mm and covered on the top with a 5mm thick infrared transmitting germanium glass window. Consequently, the temperature distribution in the channel can be observed via the window directly. In order to measure the temperature correctly, all of the aluminum channel surface substrate was anodized such that emissivity can be increased to 0.95. The results show that the temperature distribution can be measured correctly using infrared thermography. And local heat transfer coefficient can be acquired successfully.

Experiments are conducted to analyze the influence of turbulence and secondary flows on heat transfer and CHF in sub-cooled flow boiling. Inserts creating turbulence and stationary vortices are placed below a vertical channel with a heated wall and upward flow direction with flow velocities up to 1.2 m/s. The boiling chamber is of square shape with inner dimensions of 40 × 40 mm 2 . Boiling regimes range from onset of nucleate boiling up to fully developed film boiling. Influence of the inserts is measured for varying flow velocities and subcooling from 4 K to 27 K. Flow parameters are measured with Particle Image Velocimetry (PIV). A decay of nearly isotropic turbulence within only few diameters is observed, while stationary swirls exhibit longer penetration depths. Boiling experiments are conducted with unsteady heating with a low boiling hydrocarbon (dodekafluoromethylpentanone) as working fluid. Results from boiling experiments show a positive influence of the inserts on the boiling process, increasing with higher subcooling and flow velocities.

Elastomeric materials have a capability to withstand large deformations and still be able to fully recover their original dimensions. Natural and synthetic elastomers and their derivatives can reach strains as high as 500–1000%. Engineering materials, such as crystalline metals are classified as linear elastic solids, whereas elastomeric materials are considered as nonlinear elastic solids. Elastomers present a very complicated mechanical behavior that exceed the linear elastic theory and contain large deformations, plastic and viscoelastic properties. Finite element (FE) is a powerful tool to analyze such elastomers. Design of elastomeric systems in an industrial scenario generally requires (i) reliability and (ii) a minimum cycle time. This paper starts with a review of the hyperelastic theory, followed by a detailed discussion on the process involved in the material characterization of hyperelastic material like DuPont™ Viton® fluoroelastomer and polyacrylic elastomer in industrial application point of view. The paper also discusses guidelines to be followed in the various stages of material characterization such as testing, sampling and finite element simulation. Numerical stability issues associated with elastomeric modeling in finite element context and a set of guidelines to be followed in finite element analysis of elastomers are illustrated through a DuPont™ Viton® fluoroelastomer and polyacrylic elastomer pad vibration isolation systems. The above technique has been applied for designing vibration isolation systems for generators.

Reinforced concrete wall subjected to an impact by a hard steel missile with a mass of 47 kg and an impact velocity of 135 m/s was one case study in the IRIS 2010 benchmark exercise in OECD/NEA/CSNI/IAGE framework. The wall had dimensions of 2m × 2m × 0.25m and it was simply supported. The perforation of the missile was expected. Fortum Power and Heat Ltd. participated in the benchmark. In this paper, we present our modeling and blind prediction of the benchmark case. The test results of the benchmark were released after the predictions were made. Based on the result comparison, we concluded that our model gave conservative results.

Hydrogen accumulation at the top of the containment or reactor building may occur due to an interaction of molten corium and water followed by a severe accident of a nuclear reactor (TMI, Chernobyl, Fukushima Dai-ichi). Hydrogen accumulates usually in a containment of nuclear reactor as a stratified semi-confined layer of hydrogen-air mixture. Detonation of such mixture may lead to significant damage of the containment structure. A series of large scale experiments on hydrogen combustion and detonation in a semi-confined layer of uniform and non-uniform hydrogen-air mixtures in presence of obstructions or without them was performed at the Karlsruhe Institute of Technology (KIT). Critical conditions for deflagration-to-detonation transition and then for steady state detonation propagation were experimentally evaluated in a flat semi-confined layer. The experiments were performed in a horizontal semi-confined layer with dimensions of 9×3×0.6 m with/without obstacles opened from below. The hydrogen concentration in the mixtures with air was varied in the range of 0–34 vol.% without or with a gradient of 0–1.1 mol. %H 2 /cm. Effects of hydrogen concentration gradient, thickness of the layer, geometry of the obstructions, average and maximum hydrogen concentration on critical conditions for detonation onset and then propagation were investigated with respect to the safety analysis. Blast wave strength and mechanical response of the safety volume was experimentally measured as well.

The high temperature engineering test reactor (HTTR) in Japan is a 30 MW th helium-cooled and graphite-moderated reactor that was built to demonstrate the technological feasibility and advantages for the next-generation high-temperature gas-cooled reactors. The multi-level heterogeneous configuration of the HTTR core represents challenges to reactor physics calculations. A suitable core model is of vital significance for reliable neutronic analyses of the HTTR. In this study, a detailed HTTR core model is constructed based on the MCNP5 Monte Carlo code and the ENDF/B-VII neutron cross-section library. For code and model validation, several HTTR benchmark calculations were performed first and compared with the experimental results. After that, a variety of fuel design was explored to investigate their effects on the HTTR criticality calculations. The fuel design or parameters under consideration include the moderator-to-fuel ratio in the core, fuel rod dimension, and different fissile materials. The resultant trend of change in system multiplication factor and neutron spectrum was presented and discussed in this paper.

The previous work analyzed Residual Heat Removal System (RHRS) heat exchanger pressure tube failure probabilities, which were calculated using a Monte Carlo simulation. In the analysis, Probabilistic Fracture Mechanics (PFM) was used along with a Monte Carlo Simulation (MCS) to estimate the failure probability of the pressurized tubes within the heat exchanger. The Monte Carlo simulation was first conducted in MATLAB. It has been rewritten in FORTRAN, now calculating the flow rate for each failed tube out of one million trials and outputs the flow rates with their respective initial flaw dimensions. But more importantly, this program calculates the probability of a single tube failure in the RHR heat exchanger. The results from FORTRAN are consistent with those of the earlier analysis in MATLAB, validating the previous findings. While the earlier study found that tube failure was expected to be improbable for straight tubes, questions remained regarding the model’s applicability to curved sections of tubing. This additional analysis addressed those questions. The analysis focused on comparing the stress and displacement developed between the curved section of flawed a U-tube and a flawed straight tube using SolidWorks. The results from this analysis are beneficial for further understanding of the stress distribution in RHR heat exchanger tubing.

The first Molten Salt Reactor (MSR) was designed and tested at Oak Ridge National Laboratory (ORNL) in the 1960’s, but recent technological advancements now allow for new components, such as heat exchangers, to be created for the next generation of MSR’s and molten salt-cooled reactors. The primary (fuel salt-to-secondary salt) heat exchanger (PHX) design has been largely ignored up to this point; however, it is shown here that modern compact heat exchangers have the potential to make dramatic improvements over traditional shell-and-tube designs. Compact heat exchangers provide a higher effectiveness and more efficient use of material that offer a more cost-effective alternative to the massive, more expensive heat exchangers planned for the MSR. While this paper focuses on the application of compact heat exchangers on a Molten Salt Reactor, many of the analyses and results are similarly applicable to other fluid-to-fluid heat exchangers. The heat exchanger design in this study seeks to find a middle-ground between the dependable shell-and-tube design and the ultra-efficient, ultra-compact designs such as the Printed Circuit Heat Exchanger being developed today. Complex channel geometries and micro-scale dimensions in modern compact heat exchangers do not allow routine maintenance to be performed by standard procedures, so extended surfaces will be omitted and hydraulic diameters will be kept in the minichannel regime (minimum channel dimension between 200 μm and 3 mm) to allow for high-frequency eddy current inspection methods to be developed. Rather than using a “checkerboard” channel pattern, which requires complex header designs among other design challenges, row composition is homogeneous, and the borders between adjoining channels are removed to provide high aspect ratio rectangular channel cross-sections. Various plant layouts of smaller heat exchanger banks in a “modular” design are introduced, and the feasibility of casting such modules is assumed to be possible for the purposes of this research. FLUENT was used within ANSYS Workbench to find optimized heat transfer and hydrodynamic performance for straight-channel designs with two molten salts acting in pure counter-flow. Limiting the pressure drop to roughly that of ORNL’s Molten Salt Breeder Reactor’s shell-and-tube design, the compact heat exchanger design of interest in this study will lessen volume requirements, lower fuel salt volume, and decrease material usage. Compact heat exchangers have shown commercial feasibility in several industries but have yet to be assimilated into the nuclear industry. This intermediately-sized compact minichannel heat exchanger demonstrates that such a heat exchanger is viable for further testing. The original design of the MSR was an engineering marvel over 60 years ago, but several of its key components, namely the intermediate heat exchanger, must be updated in order for the MSR to reach its full potential.

The mobile cogeneration unit (MCU) consists of two gas turbines and one heat recovery steam generator mounted in a trailer with standard dimensions to supply 3 MW of electricity at ISO conditions and 14,000 to 28,000 pounds per hour of superheated steam depending on duct burner duty and steam conditions. A computational model using Thermoflex software was developed to adjust Test Cell measurements with it. The purpose of this model is to predict MCU performance in different sites of implementation. Some field measurements in Test Cell and other sites are compared with model results showing very good approach.

What I invented is a method on how to use gravitational and buoyant forces and generate multiple times more energy than energy is spent. In another words, generated energy is greater then spent energy. Even though this is considered as not possible with today’s scientific knowledge, I have experimentally proved it on miniature prototype I’ve made and tested. The measurement on my miniature prototype shows that generated energy is greater than energy we have to spend in order to produce energy. This method may provide as much energy as we want at any point on Planet Earth. There will be no need to burn gas or any other material in order to produce energy, as it is today. All energy needs anywhere in the World will be provided using this method. Today we use gasoline or other material to burn in order to produce energy. Ultimately, using this method to generate energy pollution and other environmental problems will be significantly reduced or even eliminated. The biggest obstacle with this method is to convince other people to believe that my claim is feasible in practice. Even though, I’ve made and tested prototype to prove my claim, still resistance and disbelieve exist. Reason for disbelieve is that my method violates existing First Law of Thermodynamic and therefore is considered as not possible. The method is very simple, but in order to generate significant amount of energy Multiplier Device must be quite a massive. Size of the Device is in direct proportion with energy wanted to generate. For example, Device should be about 30 feet high and 9 feet in diameter in order to produce about 5000 J/sec, which is to have power about 5kWatts. Yes, I’ve made much smaller Device to prove the feasibility of my method, by measurement and calculation. To make Energy Multiplier Device operational without any energy from outside, the size of the Device must be much greater. How the World will benefit from this project? First, this method of energy generation will allow to produce as much energy as we want at any point on Planet Earth, at least theoretically. Amount of energy produced using this method is in direct proportion with the dimensions. If we are able to make Device with unlimited height, the Device will be able to produce unlimited amount of energy. The method produces 100% clean energy, so the benefits will be: – to eliminate burning any material to produce energy; – to eliminate CO2 generation, main reason for climate change (global warming); – to significantly reduce air pollution, if not eliminate; – to eliminate environmental problems; – To provide enough energy for unlimited use; – to provide energy independence for any entity, Country, State, Household, etc; – other benefits are up to your imaginations. By the way, this project has been selected for oral presentation at World Renewable Energy Congress, Florence, Italy, 19–25 August 2006.