Download or read book Control System Options and Strategies for Supercritical CO2 Cycles written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Supercritical Carbon Dioxide (S-CO2) Brayton Cycle is a promising alternative to Rankine steam cycle and recuperated gas Brayton cycle energy converters for use with Sodium-Cooled Fast Reactors (SFRs), Lead-Cooled Fast Reactors (LFRs), as well as other advanced reactor concepts. The S-CO2 Brayton Cycle offers higher plant efficiencies than Rankine or recuperated gas Brayton cycles operating at the same liquid metal reactor core outlet temperatures as well as reduced costs or size of key components especially the turbomachinery. A new Plant Dynamics Computer Code has been developed at Argonne National Laboratory for simulation of a S-CO2 Brayton Cycle energy converter coupled to an autonomous load following liquid metal-cooled fast reactor. The Plant Dynamics code has been applied to investigate the effectiveness of a control strategy for the S-CO2 Brayton Cycle for the STAR-LM 181 MWe (400 MWt) Lead-Cooled Fast Reactor. The strategy, which involves a combination of control mechanisms, is found to be effective for controlling the S-CO2 Brayton Cycle over the complete operating range from 0 to 100 % load for a representative set of transient load changes. While the system dynamic analysis of control strategy performance for STARLM is carried out for a S-CO2 Brayton Cycle energy converter incorporating an axial flow turbine and compressors, investigations of the S-CO2 Brayton Cycle have identified benefits from the use of centrifugal compressors which offer a wider operating range, greater stability near the critical point, and potentially further cost reductions due to fewer stages than axial flow compressors. Models have been developed at Argonne for the conceptual design and performance analysis of centrifugal compressors for use in the SCO2 Brayton Cycle. Steady state calculations demonstrate the wider operating range of centrifugal compressors versus axial compressors installed in a S-CO2 Brayton Cycle as well as the benefits in expanding the range over which individual control mechanisms are effective for cycle control. However, a combination of mechanisms is still required for control of the S-CO2 Brayton Cycle between 0 and 100 % load. An effort is underway to partially validate the Argonne models and codes by means of comparison with data from tests carried out using the small-scale Sandia Brayton Loop (SBL) recuperated gas closed Brayton cycle facility. The centrifugal compressor model has been compared with data from the SBL operating with nitrogen gas and good agreement is obtained between calculations and the measured data for the compressor outlet pressure versus flow rate, although it is necessary to assume values for certain model parameters which require information about the configuration or dimensions of the compressor components that is unavailable. Unfortunately, the compressor efficiency cannot be compared with experiment data due to the lack of outlet temperature data. A radial inflow turbine model has been developed to enable further comparison of calculations with data from the SBL which incorporates both a radial inflow turbine as well as a radial compressor. Preliminary calculations of pressure ratio and efficiency versus flow rate have been carried out using the radial inflow turbine model.

Download or read book Analysis of Supercritical CO2 Cycle Control Strategies and Dynamic Response for Generation IV Reactors written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The analysis of specific control strategies and dynamic behavior of the supercritical carbon dioxide (S-CO2) Brayton cycle has been extended to the two reactor types selected for continued development under the Generation IV Nuclear Energy Systems Initiative; namely, the Very High Temperature Reactor (VHTR) and the Sodium-Cooled Fast Reactor (SFR). Direct application of the standard S-CO2 recompression cycle to the VHTR was found to be challenging because of the mismatch in the temperature drop of the He gaseous reactor coolant through the He-to-CO2 reactor heat exchanger (RHX) versus the temperature rise of the CO2 through the RHX. The reference VHTR features a large temperature drop of 450 C between the assumed core outlet and inlet temperatures of 850 and 400 C, respectively. This large temperature difference is an essential feature of the VHTR enabling a lower He flow rate reducing the required core velocities and pressure drop. In contrast, the standard recompression S-CO2 cycle wants to operate with a temperature rise through the RHX of about 150 C reflecting the temperature drop as the CO2 expands from 20 MPa to 7.4 MPa in the turbine and the fact that the cycle is highly recuperated such that the CO2 entering the RHX is effectively preheated. Because of this mismatch, direct application of the standard recompression cycle results in a relatively poor cycle efficiency of 44.9%. However, two approaches have been identified by which the S-CO2 cycle can be successfully adapted to the VHTR and the benefits of the S-CO2 cycle, especially a significant gain in cycle efficiency, can be realized. The first approach involves the use of three separate cascaded S-CO2 cycles. Each S-CO2 cycle is coupled to the VHTR through its own He-to-CO2 RHX in which the He temperature is reduced by 150 C. The three respective cycles have efficiencies of 54, 50, and 44%, respectively, resulting in a net cycle efficiency of 49.3 %. The other approach involves reducing the minimum cycle pressure significantly below the critical pressure such that the temperature drop in the turbine is increased while the minimum cycle temperature is maintained above the critical temperature to prevent the formation of a liquid phase. The latter approach also involves the addition of a precooler and a third compressor before the main compressor to retain the benefits of compression near the critical point with the main compressor. For a minimum cycle pressure of 1 MPa, a cycle efficiency of 49.5% is achieved. Either approach opens up the door to applying the SCO2 cycle to the VHTR. In contrast, the SFR system typically has a core outlet-inlet temperature difference of about 150 C such that the standard recompression cycle is ideally suited for direct application to the SFR. The ANL Plant Dynamics Code has been modified for application to the VHTR and SFR when the reactor side dynamic behavior is calculated with another system level computer code such as SAS4A/SYSSYS-1 in the SFR case. The key modification involves modeling heat exchange in the RHX, accepting time dependent tabular input from the reactor code, and generating time dependent tabular input to the reactor code such that both the reactor and S-CO2 cycle sides can be calculated in a convergent iterative scheme. This approach retains the modeling benefits provided by the detailed reactor system level code and can be applied to any reactor system type incorporating a S-CO2 cycle. This approach was applied to the particular calculation of a scram scenario for a SFR in which the main and intermediate sodium pumps are not tripped and the generator is not disconnected from the electrical grid in order to enhance heat removal from the reactor system thereby enhancing the cooldown rate of the Na-to-CO2 RHX. The reactor side is calculated with SAS4A/SASSYS-1 while the S-CO2 cycle is calculated with the Plant Dynamics Code with a number of iterations over a timescale of 500 seconds. It is found that the RHX undergoes a maximum cooldown rate of ≈ -0.3 C/s. The Plant Dynamics Code was also modified to decrease its running time by replacing the compressible flow form of the momentum equation with an incompressible flow equation for use inside of the cooler or recuperators where the CO2 has a compressibility similar to that of a liquid. Appendices provide a quasi-static control strategy for a SFR as well as the self-adaptive linear function fitting algorithm developed to produce the tabular data for input to the reactor code and Plant Dynamics Code from the detailed output of the other code.

Download or read book Fundamentals and Applications of Supercritical Carbon Dioxide SCO2 Based Power Cycles written by Klaus Brun and published by Woodhead Publishing. This book was released on 2017-01-09 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamentals and Applications of Supercritical Carbon Dioxide (SCO2) Based Power Cycles aims to provide engineers and researchers with an authoritative overview of research and technology in this area. Part One introduces the technology and reviews the properties of SCO2 relevant to power cycles. Other sections of the book address components for SCO2 power cycles, such as turbomachinery expanders, compressors, recuperators, and design challenges, such as the need for high-temperature materials. Chapters on key applications, including waste heat, nuclear power, fossil energy, geothermal and concentrated solar power are also included. The final section addresses major international research programs. Readers will learn about the attractive features of SC02 power cycles, which include a lower capital cost potential than the traditional cycle, and the compounding performance benefits from a more efficient thermodynamic cycle on balance of plant requirements, fuel use, and emissions. Represents the first book to focus exclusively on SC02 power cycles Contains detailed coverage of cycle fundamentals, key components, and design challenges Addresses the wide range of applications of SC02 power cycles, from more efficient electricity generation, to ship propulsion

Download or read book Investigation of Plant Control Strategies for the Supercritical C02Brayton Cycle for a Sodium cooled Fast Reactor Using the Plant Dynamics Code written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of a control strategy for the supercritical CO2 (S-CO2) Brayton cycle has been extended to the investigation of alternate control strategies for a Sodium-Cooled Fast Reactor (SFR) nuclear power plant incorporating a S-CO2 Brayton cycle power converter. The SFR assumed is the 400 MWe (1000 MWt) ABR-1000 preconceptual design incorporating metallic fuel. Three alternative idealized schemes for controlling the reactor side of the plant in combination with the existing automatic control strategy for the S-CO2 Brayton cycle are explored using the ANL Plant Dynamics Code together with the SAS4A/SASSYS-1 Liquid Metal Reactor (LMR) Analysis Code System coupled together using the iterative coupling formulation previously developed and implemented into the Plant Dynamics Code. The first option assumes that the reactor side can be ideally controlled through movement of control rods and changing the speeds of both the primary and intermediate coolant system sodium pumps such that the intermediate sodium flow rate and inlet temperature to the sodium-to-CO2 heat exchanger (RHX) remain unvarying while the intermediate sodium outlet temperature changes as the load demand from the electric grid changes and the S-CO2 cycle conditions adjust according to the S-CO2 cycle control strategy. For this option, the reactor plant follows an assumed change in load demand from 100 to 0 % nominal at 5 % reduction per minute in a suitable fashion. The second option allows the reactor core power and primary and intermediate coolant system sodium pump flow rates to change autonomously in response to the strong reactivity feedbacks of the metallic fueled core and assumed constant pump torques representing unchanging output from the pump electric motors. The plant behavior to the assumed load demand reduction is surprising close to that calculated for the first option. The only negative result observed is a slight increase in the intermediate inlet sodium temperatures by about 10 C. This temperature rise could presumably be precluded or significantly reduced through fine adjustment of the control rods and pump motors. The third option assumes that the reactor core power and primary and intermediate system flow rates are ideally reduced linearly in a programmed fashion that instantaneously matches the prescribed load demand. The calculated behavior of this idealized case reveals a number of difficulties because the control strategy for the S-CO2 cycle overcools the reactor potentially resulting in the calculation of sodium bulk freezing and the onset of sodium boiling. The results show that autonomous SFR operation may be viable for the particular assumed load change transient and deserves further investigation for other transients and postulated accidents.

Download or read book Development of the ANL Plant Dynamics Code and Control Strategies for the Supercritical Carbon Dioxide Brayton Cycle and Code Validation with Data from the Sandia Small scale Supercritical Carbon Dioxide Brayton Cycle Test Loop written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Significant progress has been made in the ongoing development of the Argonne National Laboratory (ANL) Plant Dynamics Code (PDC), the ongoing investigation and development of control strategies, and the analysis of system transient behavior for supercritical carbon dioxide (S-CO2) Brayton cycles. Several code modifications have been introduced during FY2011 to extend the range of applicability of the PDC and to improve its calculational stability and speed. A new and innovative approach was developed to couple the Plant Dynamics Code for S-CO2 cycle calculations with SAS4A/SASSYS-1 Liquid Metal Reactor Code System calculations for the transient system level behavior on the reactor side of a Sodium-Cooled Fast Reactor (SFR) or Lead-Cooled Fast Reactor (LFR). The new code system allows use of the full capabilities of both codes such that whole-plant transients can now be simulated without additional user interaction. Several other code modifications, including the introduction of compressor surge control, a new approach for determining the solution time step for efficient computational speed, an updated treatment of S-CO2 cycle flow mergers and splits, a modified enthalpy equation to improve the treatment of negative flow, and a revised solution of the reactor heat exchanger (RHX) equations coupling the S-CO2 cycle to the reactor, were introduced to the PDC in FY2011. All of these modifications have improved the code computational stability and computational speed, while not significantly affecting the results of transient calculations. The improved PDC was used to continue the investigation of S-CO2 cycle control and transient behavior. The coupled PDC-SAS4A/SASSYS-1 code capability was used to study the dynamic characteristics of a S-CO2 cycle coupled to a SFR plant. Cycle control was investigated in terms of the ability of the cycle to respond to a linear reduction in the electrical grid demand from 100% to 0% at a rate of 5%/minute. It was determined that utilization of turbine throttling control below 50% load improves the cycle efficiency significantly. Consequently, the cycle control strategy has been updated to include turbine throttle valve control. The new control strategy still relies on inventory control in the 50%-90% load range and turbine bypass for fine and fast generator output adjustments, but it now also includes turbine throttling control in the 0%-50% load range. In an attempt to investigate the feasibility of using the S-CO2 cycle for normal decay heat removal from the reactor, the cycle control study was extended beyond the investigation of normal load following. It was shown that such operation is possible with the extension of the inventory and the turbine throttling controls. However, the cycle operation in this range is calculated to be so inefficient that energy would need to be supplied from the electrical grid assuming that the generator could be capable of being operated in a motoring mode with an input electrical energy from the grid having a magnitude of about 20% of the nominal plant output electrical power level in order to maintain circulation of the CO2 in the cycle. The work on investigation of cycle operation at low power level will be continued in the future. In addition to the cycle control study, the coupled PDC-SAS4A/SASSYS-1 code system was also used to simulate thermal transients in the sodium-to-CO2 heat exchanger. Several possible conditions with the potential to introduce significant changes to the heat exchanger temperatures were identified and simulated. The conditions range from reactor scram and primary sodium pump failure or intermediate sodium pump failure on the reactor side to pipe breaks and valve malfunctions on the S-CO2 side. It was found that the maximum possible rate of the heat exchanger wall temperature change for the particular heat exchanger design assumed is limited to ±7 C/s for less than 10 seconds. Modeling in the Plant Dynamics Code has been compared with available data from the Sandia National Laboratories (SNL) small-scale S-CO2 Brayton cycle demonstration that is being assembled in a phased approach currently at Barber-Nichols Inc. and at SNL in the future. The available data was obtained with an earlier configuration of the S-CO2 loop involving only a single-turbo-alternator-compressor (TAC) instead of two TACs, a single low temperature recuperator (LTR) instead of both a LTR and a high temperature recuperator (HTR), and fewer than the later to be installed full set of electric heaters. Due to the absence of the full heating capability as well as the lack of a high temperature recuperator providing additional recuperation, the temperature conditions obtained with the loop are too low for the loop conditions to be prototypical of the S-CO2 cycle.

Download or read book Supercritical Carbon Dioxide Cycle Control Analysis written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This report documents work carried out during FY 2008 on further investigation of control strategies for supercritical carbon dioxide (S-CO2) Brayton cycle energy converters. The main focus of the present work has been on investigation of the S-CO2 cycle control and behavior under conditions not covered by previous work. An important scenario which has not been previously calculated involves cycle operation for a Sodium-Cooled Fast Reactor (SFR) following a reactor scram event and the transition to the primary coolant natural circulation and decay heat removal. The Argonne National Laboratory (ANL) Plant Dynamics Code has been applied to investigate the dynamic behavior of the 96 MWe (250 MWt) Advanced Burner Test Reactor (ABTR) S-CO2 Brayton cycle following scram. The timescale for the primary sodium flowrate to coast down and the transition to natural circulation to occur was calculated with the SAS4A/SASSYS-1 computer code and found to be about 400 seconds. It is assumed that after this time, decay heat is removed by the normal ABTR shutdown heat removal system incorporating a dedicated shutdown heat removal S-CO2 pump and cooler. The ANL Plant Dynamics Code configured for the Small Secure Transportable Autonomous Reactor (SSTAR) Lead-Cooled Fast Reactor (LFR) was utilized to model the S-CO2 Brayton cycle with a decaying liquid metal coolant flow to the Pb-to-CO2 heat exchangers and temperatures reflecting the decaying core power and heat removal by the cycle. The results obtained in this manner are approximate but indicative of the cycle transient performance. The ANL Plant Dynamics Code calculations show that the S-CO2 cycle can operate for about 400 seconds following the reactor scram driven by the thermal energy stored in the reactor structures and coolant such that heat removal from the reactor exceeds the decay heat generation. Based on the results, requirements for the shutdown heat removal system may be defined. In particular, the peak heat removal capacity of the shutdown heat removal loop may be specified to be 1.1 % of the nominal reactor power. An investigation of the oscillating cycle behavior calculated by the ANL Plant Dynamics Code under specific conditions has been carried out. It has been found that the calculation of unstable operation of the cycle during power reduction to 0 % may be attributed to the modeling of main compressor operation. The most probable reason for such instabilities is the limit of applicability of the currently used one-dimensional compressor performance subroutines which are based on empirical loss coefficients. A development of more detailed compressor design and performance models is required and is recommended for future work in order to better investigate and possibly eliminate the calculated instabilities. Also, as part of such model development, more reliable surge criteria should be developed for compressor operation close to the critical point. It is expected that more detailed compressor models will be developed as a part of validation of the Plant Dynamics Code through model comparison with the experiment data generated in the small S-CO2 loops being constructed at Barber-Nichols Inc. and Sandia National Laboratories (SNL). Although such a comparison activity had been planned to be initiated in FY 2008, data from the SNL compression loop currently in operation at Barber Nichols Inc. has not yet become available by the due date of this report. To enable the transient S-CO2 cycle investigations to be carried out, the ANL Plant Dynamics Code for the S-CO2 Brayton cycle was further developed and improved. The improvements include further optimization and tuning of the control mechanisms as well as an adaptation of the code for reactor systems other than the Lead-Cooled Fast Reactor (LFR). Since the focus of the ANL work on S-CO2 cycle development for the majority of the current year has been on the applicability of the cycle to SFRs, work has started on modification of the ANL Plant Dynamics Code to allow the dynamic simulation of the ABTR. The code modifications have reached the point where a transient simulation can be run in steady state mode; i.e., to determine the steady state initial conditions at full power without an initiating event. The results show that the steady state solution is maintained with minimal variations during at least 4,000 seconds of the transient. More SFR design specific modifications to the ANL Plant Dynamics Code are required to run the code in a full transient mode, including models for the sodium pumps and their control as well as models for reactivity feedback and control of the reactor power.

Download or read book Handbook of Generation IV Nuclear Reactors written by Igor Pioro and published by Woodhead Publishing. This book was released on 2022-12-07 with total page 1112 pages. Available in PDF, EPUB and Kindle. Book excerpt: Handbook of Generation IV Nuclear Reactors, Second Edition is a fully revised and updated comprehensive resource on the latest research and advances in generation IV nuclear reactor concepts. Editor Igor Pioro and his team of expert contributors have updated every chapter to reflect advances in the field since the first edition published in 2016. The book teaches the reader about available technologies, future prospects and the feasibility of each concept presented, equipping them users with a strong skillset which they can apply to their own work and research. Provides a fully updated, revised and comprehensive handbook dedicated entirely to generation IV nuclear reactors Includes new trends and developments since the first publication, as well as brand new case studies and appendices Covers the latest research, developments and design information surrounding generation IV nuclear reactors

Download or read book Applications of Supercritical Carbon Dioxide Based Power Cycles written by and published by . This book was released on 2018-05 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt: Supercritical CO2 (sCO2) cycles are being considered for future fossil energy systems. These sCO2 systems deliver the prospect of improved efficiency combined with smaller turbo -machinery size compared to a traditional Rankine steam system if operated at turbine inlet temperatures up to 760°C. Supercritical CO2 cycles have been investigated since the 1960s, but technical limitations, both computational and physical, prevented major strides on the subject until the turn of the millennium. Since then, numerous studies have investigated and conceptualized various sCO2 cycles: as standalone power cycles for nuclear applications, in concentrated solar power plants or for waste heat recovery. Many of these studies were conducted using established performance simulation tools such as NPSS, which were expanded in their functionality through supercritical CO2 fluid property functions.Fundamentals and Applications of Supercritical Carbon Dioxide (sCO2) Based Power Cycles provides up-to-date information of research and technology in this field. This book addresses components for sCO2 power cycles, such as turbomachinery expanders, compressors, recuperators, and design challenges, such as the need for high-temperature materials. The attractive features of sC02 power cycles are addressed. The supercritical CO2 (sCO2) Brayton cycle has recently been gaining a lot of attention for application to next generation nuclear reactors. The advantages of the sCO2 cycle are high efficiency in the mild turbine inlet temperature region and a small physical footprint with a simple layout, compact turbomachinery, and heat exchangers. Currently sCO2 cycles are being investigated primarily for stationary power applications, but their high power density and efficiency, even for modest peak cycle temperatures, makes them credible bottoming cycle options for aero engine applications. To successfully utilize the high reactor outlet temperature, interest in alternative power conversion systems is also increasing. The steam Rankine cycle and gas turbine systems have been utilized by large size power plants for several decades.This book will appeal to students, practitioners, as well as researchers dealing with this field.

Download or read book Control Strategies for Supercritical Carbon Dioxide Power Conversion Systems written by Nathan Carstens and published by . This book was released on 2007 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: Coding innovations have made faster than real time simulation possible (on today's off the shelf hardware), which makes plant simulator and control applications feasible. This code was used to devise and investigate some of the major control strategies required to operate the cycle: high and low temperature control, three variations of turbine bypass, and inventory control. Using these strategies various transients were investigated including part-load operation, loss-of-load, loss of heat sink, over-power, and startup/shutdown.

Download or read book Performance Improvement Options for the Supercritical Carbon Dioxide Brayton Cycle written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The supercritical carbon dioxide (S-CO2) Brayton cycle is under development at Argonne National Laboratory as an advanced power conversion technology for Sodium-Cooled Fast Reactors (SFRs) as well as other Generation IV advanced reactors as an alternative to the traditional Rankine steam cycle. For SFRs, the S-CO2 Brayton cycle eliminates the need to consider sodium-water reactions in the licensing and safety evaluation, reduces the capital cost of the SFR plant, and increases the SFR plant efficiency. Even though the S-CO2 cycle has been under development for some time and optimal sets of operating parameters have been determined, those earlier development and optimization studies have largely been directed at applications to other systems such as gas-cooled reactors which have higher operating temperatures than SFRs. In addition, little analysis has been carried out to investigate cycle configurations deviating from the selected 'recompression' S-CO2 cycle configuration. In this work, several possible ways to improve S-CO2 cycle performance for SFR applications have been identified and analyzed. One set of options incorporates optimization approaches investigated previously, such as variations in the maximum and minimum cycle pressure and minimum cycle temperature, as well as a tradeoff between the component sizes and the cycle performance. In addition, the present investigation also covers options which have received little or no attention in the previous studies. Specific options include a 'multiple-recompression' cycle configuration, intercooling and reheating, as well as liquid-phase CO2 compression (pumping) either by CO2 condensation or by a direct transition from the supercritical to the liquid phase. Some of the options considered did not improve the cycle efficiency as could be anticipated beforehand. Those options include: a double recompression cycle, intercooling between the compressor stages, and reheating between the turbine stages. Analyses carried out as part of the current investigation confirm the possibilities of improving the cycle efficiency that have been identified in previous investigations. The options in this group include: increasing the heat exchanger and turbomachinery sizes, raising of the cycle high end pressure (although the improvement potential of this option is very limited), and optimization of the low end temperature and/or pressure to operate as close to the (pseudo) critical point as possible. Analyses carried out for the present investigation show that significant cycle performance improvement can sometimes be realized if the cycle operates below the critical temperature at its low end. Such operation, however, requires the availability of a heat sink with a temperature lower than 30 C for which applicability of this configuration is dependent upon the climate conditions where the plant is constructed (i.e., potential performance improvements are site specific). Overall, it is shown that the S-CO2 Brayton cycle efficiency can potentially be increased to 45 %, if a low temperature heat sink is available and incorporation of larger components (e.g., heat exchangers or turbomachinery) having greater component efficiencies does not significantly increase the overall plant cost.

Download or read book Organic Rankine Cycle ORC Power Systems written by Ennio Macchi and published by Woodhead Publishing. This book was released on 2016-08-24 with total page 700 pages. Available in PDF, EPUB and Kindle. Book excerpt: Organic Rankine Cycle (ORC) Power Systems: Technologies and Applications provides a systematic and detailed description of organic Rankine cycle technologies and the way they are increasingly of interest for cost-effective sustainable energy generation. Popular applications include cogeneration from biomass and electricity generation from geothermal reservoirs and concentrating solar power installations, as well as waste heat recovery from gas turbines, internal combustion engines and medium- and low-temperature industrial processes. With hundreds of ORC power systems already in operation and the market growing at a fast pace, this is an active and engaging area of scientific research and technical development. The book is structured in three main parts: (i) Introduction to ORC Power Systems, Design and Optimization, (ii) ORC Plant Components, and (iii) Fields of Application. Provides a thorough introduction to ORC power systems Contains detailed chapters on ORC plant components Includes a section focusing on ORC design and optimization Reviews key applications of ORC technologies, including cogeneration from biomass, electricity generation from geothermal reservoirs and concentrating solar power installations, waste heat recovery from gas turbines, internal combustion engines and medium- and low-temperature industrial processes Various chapters are authored by well-known specialists from Academia and ORC manufacturers

Download or read book Modeling the Supercritical Carbon Dioxide Brayton Cycle with Recompression written by and published by . This book was released on 2014 with total page 155 pages. Available in PDF, EPUB and Kindle. Book excerpt: Supercritical carbon dioxide (SCO2) power cycles show promise for a wide range of applications, such as concentrating solar power, next-generation nuclear reactors, and waste-heat recovery. Models capable of predicting the design-point, off-design, and part-load performance of SCO2 power cycles are necessary for evaluating cycle designs. These models should be flexible in order to accommodate the range of designs under consideration and computationally efficient in order to enable timely optimization studies, possibly while considering cycle performance on an annual or life-cycle basis. This document reports on the development of a modeling framework that accommodates these requirements and is capable of predicting the performance of recuperated and recompression cycle configurations. The modeling framework is in Fortran and is flexible with respect to component-level specifics, such as the type of compressor used in the cycle or the method used to represent the off-design performance of the turbine. Optimization routines are integrated into the models, allowing exploration of optimal component and system designs or optimal operating strategies for a given system design. The optimal design-point and off-design performance of various cycle designs is predicted using turbomachinery models based on the radial compressors and turbines that are currently being investigated by Sandia National Laboratory for use in SCO2 applications. A range of heat rejection (low-side) temperatures are considered and results indicate that operating the cycles at warmer low-side temperatures requires a corresponding increase in low-side pressure in order to maximize thermal efficiency. The relationship between low-side temperature and pressure suggests that inventory control (i.e., actively controlling the low-side pressure) is a favorable control mechanism, especially if the power plant is expected to operate away from its design point for significant periods of time. For cycles designed to operate at warmer heat rejection temperatures (e.g., a dry-cooled design in an arid climate), the benefits of recompression are reduced and a simple recuperated cycle may be favorable. The optimal SCO2 Brayton cycle design depends on the application being considered, and the developed modeling framework provides the consistent performance predictions that are required for further application-specific analyses.

Download or read book Conception and Optimization of Supercritical CO2 Brayton Cycles for Coal fired Power Plant Application written by Qiao Zhao and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Efficiency enhancement in power plant can be seen as a key lever in front of increasing energy demand. Nowadays, both the attention and the emphasis are directed to reliable alternatives, i.e., enhancing the energy conversion systems. The supercritical CO2 (SC-CO2) Brayton cycle has recently emerged as a promising solution for high efficiency power production in nuclear, fossil-thermal and solar-thermal applications. Currently, studies on such a thermodynamic power cycle are directed towards the demonstration of its reliability and viability before the possible building of an industrial-scale unit. The objectives of this PhD can be divided in two main parts: • A rigorous selection procedure of an equation of state (EoS) for SC-CO2 which permits to assess influences of thermodynamic model on the performance and design of a SC-CO2 Brayton cycle. • A framework of optimization-based synthesis of energy systems which enables optimizing both system structure and the process parameters. The performed investigations demonstrate that the Span-Wagner EoS is recommended for evaluating the performances of a SC-CO2 Brayton cycle in order to avoid inaccurate predictions in terms of equipment sizing and optimization. By combining a commercial process simulator and an evolutionary algorithm (MIDACO), this dissertation has identified a global feasible optimum design -or at least competitive solutions- for a given process superstructure under different industrial constraints. The carried out optimization firstly base on cycle energy aspects, but the decision making for practical systems necessitates techno-economic optimizations. The establishment of associated techno-economic cost functions in the last part of this dissertation enables to assess the levelized cost of electricity (LCOE). The carried out multi-objective optimization reflects the trade-off between economic and energy criteria, but also reveal the potential of this technology in economic performance.

Download or read book Advanced Power Generation Systems written by Ibrahim Dincer and published by Academic Press. This book was released on 2014-07-15 with total page 657 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced Power Generation Systems examines the full range of advanced multiple output thermodynamic cycles that can enable more sustainable and efficient power production from traditional methods, as well as driving the significant gains available from renewable sources. These advanced cycles can harness the by-products of one power generation effort, such as electricity production, to simultaneously create additional energy outputs, such as heat or refrigeration. Gas turbine-based, and industrial waste heat recovery-based combined, cogeneration, and trigeneration cycles are considered in depth, along with Syngas combustion engines, hybrid SOFC/gas turbine engines, and other thermodynamically efficient and environmentally conscious generation technologies. The uses of solar power, biomass, hydrogen, and fuel cells in advanced power generation are considered, within both hybrid and dedicated systems. The detailed energy and exergy analysis of each type of system provided by globally recognized author Dr. Ibrahim Dincer will inform effective and efficient design choices, while emphasizing the pivotal role of new methodologies and models for performance assessment of existing systems. This unique resource gathers information from thermodynamics, fluid mechanics, heat transfer, and energy system design to provide a single-source guide to solving practical power engineering problems. The only complete source of info on the whole array of multiple output thermodynamic cycles, covering all the design options for environmentally-conscious combined production of electric power, heat, and refrigeration Offers crucial instruction on realizing more efficiency in traditional power generation systems, and on implementing renewable technologies, including solar, hydrogen, fuel cells, and biomass Each cycle description clarified through schematic diagrams, and linked to sustainable development scenarios through detailed energy, exergy, and efficiency analyses Case studies and examples demonstrate how novel systems and performance assessment methods function in practice

Download or read book Supercritical CO2 Cycles in Combined cycle Power Systems written by Mohamed Bahaa Noaman and published by . This book was released on 2022 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Operation and Analysis of a Supercritical CO2 Brayton Cycle written by and published by . This book was released on 2010 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sandia National Laboratories is investigating advanced Brayton cycles using supercritical working fluids for use with solar, nuclear or fossil heat sources. The focus of this work has been on the supercritical CO2 cycle (S-CO2) which has the potential for high efficiency in the temperature range of interest for these heat sources, and is also very compact, with the potential for lower capital costs. The first step in the development of these advanced cycles was the construction of a small scale Brayton cycle loop, funded by the Laboratory Directed Research & Development program, to study the key issue of compression near the critical point of CO2. This document outlines the design of the small scale loop, describes the major components, presents models of system performance, including losses, leakage, windage, compressor performance, and flow map predictions, and finally describes the experimental results that have been generated.

Download or read book Development and Application of a Steady State Code for Supercritical Carbon Dioxide Cycles written by David Michael Legault and published by . This book was released on 2006 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: The supercritical CO2 power conversion system is of interest for advanced nuclear reactor applications because the same efficiencies are obtained as for the most developed of the closed gas-turbine cycles (helium-Brayton), but at lower temperatures and higher pressures. The original in-house code, named CYCLES, could potentially be used by others who are researching the S-CO2 cycle, but it has its shortcomings. In particular, CYCLES does not factor in the pressure drops due to pipes and plena. Also, for new users, it takes a significant amount of time to fully understand how to use the code. The objectives of this thesis were to modify CYCLES to ensure that pipe and plena effects were included, and to improve the readability and functionality of the code. Changes to CYCLES are included in the rewritten code, named CYCLES II, and are also documented in this thesis. Furthermore, documentation of the program input and output is given, along with a flow chart of the algorithm logic. Two applications of the code are provided to show the effect of the pipes and plena on cycle performance. In comparing the cycle efficiency with and without the effects of the pipes and plena, for a 300 MWe S-CO2 Brayton power conversion system, the results indicate that the net cycle efficiency drops from 49% to 45% when pipes and plena of reasonable dimensions are included in the calculations. The losses are dominated by the low pressure pipe and plena segments. However, the effects of the pipes and plena on cycle efficiency are not characteristic of the S-CO2 cycle only. All Brayton cycles have this same issue, and the effects are worse for the helium-Brayton cycle because it operates at lower pressures.