Digital Twin for Power Plants, Energy Savings and other Complex Engineering Systems

Digital Twin (DT) is a digital representation of a machine, service, or production system that consists of models, information, and data used to characterize properties, conditions, and behavior of the system. Renewable energy integration will make future power plants more complex with addition of varieties of Power-to-X technologies, Electrolysis to green hydrogen, onsite storage and transport of hydrogen, and use of pure or blended hydrogen, etc. These future power plants need robust DT architecture to achieve high Reliability, Availability and Maintainability at lower cost. In this research work, a comprehensive and robust DT architecture for power plants is proposed that also can be implemented in other similar complex capital-intensive large engineering systems. The novelty and advantages of the proposed DT is asserted by reviewing the state-of-the-art of DT in energy industries and its potential to transform these industries. Then the proposed DT architecture and its five components are explained and discussed. More specifically, the main contributions of the present work include: 1. Overview of DT key research and development for energy savings applications to consider important findings, research gaps and the needed future development for the proposed DT for power plants. 2. Overview of DT key research for power plants including applications, frameworks and architectures to consider important findings and to confirm the novelty and robustness of the proposed DT. 3. Proposing and demonstrating new robust DT architecture for power plants and other similar complex capital-intensive large engineering systems

Miniature high speed compressor having embedded permanent magnet motor

A high speed centrifugal compressor for compressing fluids includes a permanent magnet synchronous motor (PMSM) having a hollow shaft, the being supported on its ends by ball bearing supports. A permanent magnet core is embedded inside the shaft. A stator with a winding is located radially outward of the shaft. The PMSM includes a rotor including at least one impeller secured to the shaft or integrated with the shaft as a single piece. The rotor is a high rigidity rotor providing a bending mode speed of at least 100,000 RPM which advantageously permits implementation of relatively low-cost ball bearing supports

Simulation Of Low Speed Gas Flow Over Backward Facing Step In Microchannels

Proper design of thermal management solutions for future nano-scale electronics or photonics will require knowledge of flow and transport through micron-scale ducts. As in the macro-scale conventional counterparts, such micron-scale flow systems would require robust simulation tools for early-stage design iterations. This paper concentrates on such a flow process, namely pressure-driven gas flow over a backward facing step in a microchannel. A well-known particle-based method, Direct Simulation Monte Carlo (DSMC) is used as the simulation tool. Separating the macroscopic velocity from the molecular velocity through the use of the Information Preservation (IP) method eliminates the high-level of statistical noise as typical in DSMC calculations of low-speed flows. The non-isothermal IP method is further modified to incorporate the pressure boundary conditions, which are expected to be more prevalent in design of thermal management systems. The applicability of the method in solving a real flow situation is verified using the backward facing step flow in a micro geometry. The flow and heat transfer mechanisms at different pressures in Knudsen transient regime are investigated. The range of parameters for this investigation are: Re from 0.03 to 0.64, Ma from 0.013 to 0.083, and Kn from 0.24 to 4.81, all based on maximum values. Copyright © 2006 by ASME

Evaluating the Effect on Component Cooling and Thermally Generated Stress Caused by Variation of Internal Heat Transfer Coefficients Through an Uncertainty Quantification

Through the use of probabilistic design a process is developed to simulate variation of internal heat transfer coefficient. It is then applied to a non-rotating blade component, internally cooled through mutli-pass serpentine channels. While keeping the external parameters constant the internal heat transfer coefficient variation is then simulated in regions of high uncertainty, such as tip and hub turns, and the effect on the thermally generated stress of the airfoil is evaluated using ANSYS. Through a change in heat transfer coefficients the fluid temperatures will also vary, which is captured in the integrated fluid dynamics model. Although other cooling features such as film cooling, as well as any impingement flow is not considered in this study, the effects on the fluid dynamics model are incorporated through advection and fluid elements. Copyright © 2011 by the American Institute of Aeronautics and Astronautics, Inc

Study Of Transitional Regime Gas Flows Over A Backward-Facing Step

As in the macro-scale conventional counterparts, microscale flow systems require robust simulation tools for early-stage design iterations. This paper concentrates on a typical such flow process, namely flow over a backward facing step. Direct simulation Monte Carlo (DSMC) is used as the simulation tool. Separating the macroscopic velocity from the molecular velocity through the use of the IP method eliminates the high-level of statistical noise as typical in DSMC calculation of low-speed flows. The non-isothermal IP method is modified to incorporate the pressure boundary conditions, which are expected to be more prevalent in design of thermal management systems. The flow mechanisms over a backward-facing step in a microchanael at different pressures are investigated. The range of parameter values for this investigation are: Re from 0.03 to 0.64, Ma from 0.013 to 0.083, and Kn from 0.24 to 4.81, all based on maximum values

Large-Eddy Simulations Of A Cylindrical Film Cooling Hole

Large-eddy simulations are used to explore the unsteady jet-in-crossflow interactions arising from discrete hole film cooling from a cylindrical hole. The numerical grids are created using GridPro and solved in OpenFOAM. A recycling-rescaling technique is used to generate a realistic turbulent incoming boundary layer upstream of injection. The simulations match the conditions of an experiment in the open literature for the robust validation of the numerical solution and turbulence modeling. The current study tests the ability of large-eddy simulations in predicting film cooling flows using detailed experimental measurements. The large-eddy simulation results compared favorably with the experimental data except in areas close to the injection site and close to the wall. Grid resolution is discussed in terms of the percent turbulent kinetic energy resolved and related to the success of the large eddy simulation predictions in different regions of the jet. No substantial benefit was seen by using a dynamic Smagorinsky model for the subgrid turbulent heat fluxes instead of a constant subgrid Prandtl number. The trajectories, spreading rates, and large turbulent structures of the jet are discussed in terms of the hydrodynamic parameters such as velocity ratio and momentum ratio. © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved

Effect Of Increasing Pitch-To-Diameter Ratio On The Film Cooling Effectiveness Of Shaped And Cylindrical Holes Embedded In Trenches

The continuous push for higher gas turbine inlet temperatures and operating efficiencies has led to increasingly sophisticated film cooling schemes. One such setup - trench cooling - consists of having film cooling holes embedded inside a gap, commonly called a trench. The coolant hits the downstream trench wall which forces it to spread laterally, resulting in more even film coverage downstream. Recent literature has focused on the effect that trenching has on cylindrical cooling holes only. In addition, researchers have limited their findings to a narrow range of pitch-to-diameter ratios (P/D). The current trends in the turbine industry of increasing or maintaining film cooling effectiveness while reducing the amount of coolant used dictate that P/D be increased, meaning less holes per row. In this study, we address both cylindrical and fan-shaped holes embedded in trenches. Tests have been conducted on 8 test plates with one row of cooling holes each varying the pitch-to-diameter ratio from 4 to 12 (12 configurations in total), and the blowing ratios from 0.5 to 2.0. We investigate the effect that P/D has on film cooling effectiveness for both hole geometries and compare them to similarly pitched baseline plates - fan and cylindrical - not in trenches. It is a known fact that increasing the pitch between holes, while maintaining all other conditions constant, decreases the average film effectiveness, however trenching has been shown to significantly increase film coverage. In this study, it has been shown that film cooling effectiveness of a cylindrical configuration can be maintained by the addition of a trench while cutting the number of holes in half. We also explore the behavior of shaped trenched holes, of which little has been said and find that their performance is actually hurt by trenching. Copyright © 2009 by ASME

Coupled Zero-Dimensional/One-Dimensional Model For Hybrid Heat Transfer Measurements

This paper covers the application of an improved model to address errors associated with transient heat transfer experiments, which also include the application of lumped capacitance. Using transient thermochromic liquid crystals techniques, and applying thermochromic liquid crystals underneath lumpable features, it is possible to calculate the heat transfer using a lumped heat capacitance approach. In previous studies using the classical lumped capacitance model, the heat loss into the surface underneath the lumped features was not accounted for. In this paper, an exact, closed-form analytical solution to the enhanced lumped capacitance model is derived for discrete bodies for the case of perfect thermal contact. To validate the model and its exact solution, the transient heat conduction in a representative two-dimensional ribbed surface is simulated numerically using the finite volume method. The modeled behavior of the coupled zero-dimensional/one-dimensional model has reasonable agreement with the numerical simulation. The solution for perfect contact can also be extended for imperfect contact. © 2013 by the American Institute of Aeronautics and Astronautics, Inc

Large Eddy Simulations Of A Cylindrical Film Cooling Hole

Large Eddy Simulations are used to explore the unsteady jet-in-crossflow interactions arising from discrete hole film cooling. The numerical grids are created using GridPro and exported into OpenFOAM for solution with specified initial and boundary conditions. A recycling-rescaling technique is used to generate an incoming turbulent boundary layer upstream of injection. The geometry and flow conditions are specified to match conditions of an experiment in open literature for robust validation of the numerical solution. The trajectory and spreading of the jet is discussed in terms of the insight provided by the results of the simulation. Copyright © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved

Molecular Dynamics Simulation Of Adsorbent Layer Effect On Tangential Momentum Accommodation Coefficient

The tangential momentum accommodation coefficient (TMAC) is used to improve the accuracy of fluid flow calculations in the slip flow regime where the continuum assumption of zero fluid velocity at the surface is inaccurate because fluid slip occurs. Molecular dynamics techniques are used to study impacts of individual gas atoms upon solid surfaces to understand how approach velocity, crystal geometry, interatomic forces, and adsorbed layers affect the scattering of gas atoms, and their tangential momentum. It is a logical step in development of techniques estimating total TMAC values for investigating flows in micro- and nano-channels or orbital spacecraft where slip flow occurs. TMAC can also help analysis in transitional or free molecular flow regimes. The impacts were modeled using Lennard-Jones potentials. Solid surfaces were modeled approximately three atoms wide by three atoms deep by 40 or more atoms long face centered cubic (100) crystals. The gas was modeled as individual free atoms. Gas approach angles were varied from 10 to 70 deg from normal. Gas speed was either specified directly or using a ratio relationship with the Lennard-Jones energy potential (energy ratio). To adequately model the trajectories and maintain conservation of energy, very small time steps (approximately 0.0005 of the natural time unit) were used. For each impact the initial and final tangential momenta were determined and after many atoms, TMAC was calculated. The modeling was validated with available experimental data for He gas atoms at 1770 m/s impacting Cu at the given angles. The model agreed within 3% of experimental values and correctly predicted that TMAC changes with angle. Molecular Dynamics results estimate TMAC values from high of 1.2 to low of 0.25, generally estimating higher coefficients at the smaller angles. TMAC values above 1.0 indicate backscattering, which numerous experiments have observed. The ratio of final to initial momentum, when plotted for a gas atom sequence spaced across a lattice cycle typically follows a discontinuous curve, with continuous portions forward and backscattering and discontinuous portions indicating multiple bounces. Increasing the energy ratio above a value of 5 tends to decrease TMAC at all angles. Adsorbed layers atop a surface influence the TMAC in accordance with their energy ratio. Even a single adsorbed layer can have a substantial effect, changing TMAC +/-20%. The results provide encouragement to continue model development and next evaluate gas flows with Maxwell temperature distributions involving numerous impact angles simultaneously. Copyright © 2007 by ASME