scholarly journals Octane Index Applicability over the Pressure-Temperature Domain

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 607
Author(s):  
Tommy R. Powell ◽  
James P. Szybist ◽  
Flavio Dal Forno Chuahy ◽  
Scott J. Curran ◽  
John Mengwasser ◽  
...  
Keyword(s):  
High Efficiency ◽  
National Laboratory ◽  
Operating Conditions ◽  
Dominant Factor ◽  
Compression Ignition ◽  
Oak Ridge ◽  
Operating Modes ◽  
Wide Range ◽  
Thermodynamic Conditions ◽  
Si Engines

Modern boosted spark-ignition (SI) engines and emerging advanced compression ignition (ACI) engines operate under conditions that deviate substantially from the conditions of conventional autoignition metrics, namely the research and motor octane numbers (RON and MON). The octane index (OI) is an emerging autoignition metric based on RON and MON which was developed to better describe fuel knock resistance over a broader range of engine conditions. Prior research at Oak Ridge National Laboratory (ORNL) identified that OI performs reasonably well under stoichiometric boosted conditions, but inconsistencies exist in the ability of OI to predict autoignition behavior under ACI strategies. Instead, the autoignition behavior under ACI operation was found to correlate more closely to fuel composition, suggesting fuel chemistry differences that are insensitive to the conditions of the RON and MON tests may become the dominant factor under these high efficiency operating conditions. This investigation builds on earlier work to study autoignition behavior over six pressure-temperature (PT) trajectories that correspond to a wide range of operating conditions, including boosted SI operation, partial fuel stratification (PFS), and spark-assisted compression ignition (SACI). A total of 12 different fuels were investigated, including the Co-Optima core fuels and five fuels that represent refinery-relevant blending streams. It was found that, for the ACI operating modes investigated here, the low temperature reactions dominate reactivity, similar to boosted SI operating conditions because their PT trajectories lay close to the RON trajectory. Additionally, the OI metric was found to adequately predict autoignition resistance over the PT domain, for the ACI conditions investigated here, and for fuels from different chemical families. This finding is in contrast with the prior study using a different type of ACI operation with different thermodynamic conditions, specifically a significantly higher temperature at the start of compression, illustrating that fuel response depends highly on the ACI strategy being used.

Sensitivity Analysis of Combustion Timing of Homogeneous Charge Compression Ignition Gasoline Engines

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Chia-Jui Chiang ◽  
Anna G. Stefanopoulou
Keyword(s):  
Sensitivity Analysis ◽  
Homogeneous Charge Compression Ignition ◽  
Quantitative Information ◽  
Operating Conditions ◽  
Dominant Factor ◽  
Compression Ignition ◽  
Hcci Engine ◽  
Wide Range ◽  
Start Of Combustion ◽  
Homogeneous Charge

The goal of this paper is to identify the dominant factors that should be included in a control oriented model in order to predict the start of combustion in a homogeneous charge compression ignition (HCCI) engine. Qualitative and quantitative information on the individual effects of fuel and exhaust gas recirculation on the HCCI combustion is provided. Using sensitivity analysis around a wide range of operating conditions of a single-cylinder port-injection gasoline HCCI engine, we find that temperature is the dominant factor in determining the start of combustion. Charge temperature thus becomes the “spark” in a HCCI engine. Therefore, a model without the composition terms should be adequate for model based regulation of the combustion timing in a port-injection gasoline HCCI engine with high dilution from the exhaust.

Investigating realistic anode off-gas combustion in SOFC/ICE hybrid systems: mini review and experimental evaluation

2021 ◽  
pp. 146808742110583
Author(s):  
Ioannis Nikiforakis ◽  
Zhongnan Ran ◽  
Michael Sprengel ◽  
John Brackett ◽  
Guy Babbit ◽  
...  
Keyword(s):  
Thermal Efficiency ◽  
Internal Combustion Engines ◽  
Engine Performance ◽  
High Energy ◽  
Operating Conditions ◽  
Compression Ignition ◽  
Case Scenario ◽  
Gas Combustion ◽  
Thermodynamic Conditions ◽  
Decentralized Energy

Solid oxide fuel cells (SOFCs) have been deployed in hybrid decentralized energy systems, in which they are directly coupled to internal combustion engines (ICEs). Prior research indicated that the anode tailgas exiting the SOFC stack should be additionally exploited due to its high energy value, with typical ICE operation favoring hybridization due to matching thermodynamic conditions during operation. Consequently, extensive research has been performed, in which engines are positioned downstream the SOFC subsystem, operating in several modes of combustion, with the most prevalent being homogeneous compression ignition (HCCI) and spark ignition (SI). Experiments were performed in a 3-cylinder ICE operating in the latter modus operandi, where the anode tailgas was assimilated by mixing syngas (H2: 33.9%, CO: 15.6%, CO2: 50.5%) with three different water vapor flowrates in the engine’s intake. While increased vapor content significantly undermined engine performance, brake thermal efficiency (BTE) surpassed 34% in the best case scenario, which outperformed the majority of engines operating under similar operating conditions, as determined from the conducted literature review. Nevertheless, the best performing application was identified operating under HCCI, in which diesel reformates assimilating SOFC anode tailgas, fueled a heavy duty ICE (17:1), and gross indicated thermal efficiency ([Formula: see text]) of 48.8% was achieved, with the same engine exhibiting identical performance when operating in reactivity-controlled compression ignition (RCCI). Overall, emissions in terms of NOx and CO were minimal, especially in SI engines, while unburned hydrocarbons (UHC) were non-existent due to the absence of hydrocarbons in the assessed reformates.

scholarly journals Development of the PGT 25 High Efficiency Gas Turbine: Part 2 — Aerodynamic Design and Performance

1984 ◽  
Author(s):  
E. Benvenuti ◽  
B. Innocenti ◽  
R. Modi
Keyword(s):  
Gas Turbine ◽  
High Efficiency ◽  
Performance Testing ◽  
Operating Conditions ◽  
Aerodynamic Design ◽  
Direct Drive ◽  
Gas Generator ◽  
Full Load ◽  
Wide Range ◽  
Overall Performance

This paper outlines parameter selection criteria and major procedures used in the PGT 25 gas turbine power spool aerodynamic design; significant results of the shop full-load tests are also illustrated with reference to both overall performance and internal flow-field measurements. A major aero-design objective was established as that of achieving the highest overall performance levels possible with the matching to latest generation aero-derivative gas generators; therefore, high efficiencies were set as a target both for the design point and for a wide range of operating conditions, to optimize the turbine’s uses in mechanical drive applications. Furthermore, the design was developed to reach the performance targets in conjunction with the availability of a nominal shaft speed optimized for the direct drive of pipeline booster centrifugal compressors. The results of the full-load performance testing of the first unit, equipped with a General Electric LM 2500/30 gas generator, showed full attainment of the design objectives; a maximum overall thermal efficiency exceeding 37% at nominal rating and a wide operating flexibility with regard to both efficiency and power were demonstrated.

Mechanical Design and Testing of a 2.5 MW sCO2 Compressor Loop

2021 ◽  
Author(s):  
Stefan D. Cich ◽  
J. Jeffrey Moore ◽  
Chris Kulhanek ◽  
Meera Day Towler ◽  
Jason Mortzheim
Keyword(s):  
High Efficiency ◽  
Mechanical Design ◽  
Guide Vane ◽  
Operating Conditions ◽  
Inlet Guide Vane ◽  
Inlet Temperature ◽  
Design Changes ◽  
Wide Range ◽  
Inlet Conditions ◽  
Design And Testing

Abstract An enabling technology for a successful deployment of the sCO2 close-loop recompression Brayton cycle is the development of a compressor that can maintain high efficiency for a wide range of inlet conditions due to large variation in properties of CO2 operating near its dome. One solution is to develop an internal actuated variable Inlet Guide Vane (IGV) system that can maintain high efficiency in the main and re-compressor with varying inlet temperature. A compressor for this system has recently been manufactured and tested at various operating conditions to determine its compression efficiency. This compressor was developed with funding from the US DOE Apollo program and industry partners. This paper will focus on the design and testing of the main compressor operating near the CO2 dome. It will look at design challenges that went into some of the decisions for rotor and case construction and how that can affect the mechanical and aerodynamic performance of the compressor. This paper will also go into results from testing at the various operating conditions and how the change in density of CO2 affected rotordynamics and overall performance of the machine. Results will be compared to expected performance and how design changes were implanted to properly counter challenges during testing.

The LAJ Cycle: A New Combined-Cycle Fossil Fuel Power System

2002 ◽  
Author(s):  
Roddie R. Judkins ◽  
Timothy R. Armstrong ◽  
Solomon D. Labinov
Keyword(s):  
Fuel Cells ◽  
Natural Gas ◽  
Power System ◽  
Fossil Fuel ◽  
High Efficiency ◽  
National Laboratory ◽  
Combined Cycle ◽  
Mitigation Strategies ◽  
Model Calculations ◽  
Oak Ridge

Oak Ridge National Laboratory (ORNL) has developed a novel system for combined-cycle power generation, called the LAJ cycle. This system could serve as a basis for the development of a new generation of high-efficiency combined cycles. In one of several possible configurations of the new combined-cycle fossil fuel power system, natural gas enters the system at 4.0 MPa and about 300 K, is heated and reformed, and is transferred to a turbine at 4.0 MPa and 1200 K. The gas expands in the turbine to 0.6 MPa and 800 K, and then flows successively to heat exchangers and a condenser-separator, after which it is separated into two gas streams, one containing principally CO with some CH4 and water vapor and the other containing pure H2. The CO and H2 flow to separate fuel cells and undergo electrochemical oxidation with the concomitant production of electricity. Separate streams of water and carbon dioxide (CO2) are produced, making this cycle compatible with carbon mitigation strategies based on sequestration. Model calculations indicate combined-cycle efficiencies greater than 70% based on the lower heating value of natural gas. The high efficiencies realized result from a combination of the high-pressure natural gas reformate expansion and the highly efficient CO and H2 fuel cells. Most of the power derives from the fuel cells in the system.

scholarly journals Shared Research Equipment at OAK Ridge National Laboratory

1998 ◽  
Vol 4 (S2) ◽  
pp. 470-471
Author(s):  
N. D. Evans ◽  
E. A. Kenik ◽  
M. K. Miller
Keyword(s):  
Semiconductor Device ◽  
National Laboratory ◽  
Atomic Scale ◽  
Fiscal Year ◽  
Probe Field ◽  
Oak Ridge ◽  
Wide Range ◽  
Oak Ridge National Laboratory ◽  
Electron Microscopes ◽  
Research Equipment

The Shared Research Equipment (SHaRE) User Facility and Program at Oak Ridge National Laboratory (ORNL) provides microanalytical facilities for studies within the materials sciences. Available instrumentation includes advanced analytical electron microscopes, atom probe field ion microscopes, and nanoindentation facilities. Through SHaRE, researchers from U.S. universities, industries, and government laboratories may collaborate with Facility scientists to perform research not possible at their home institutions. International collaborations are also possible. Most SHaRE projects seek correlations at the microscopic or atomic scale between structure and properties in a wide range of metallic, ceramic, and other structural materials. Typical research projects include studies of magnetic materials, advanced alloys, catalysts, semiconductor device materials, high Tc superconductors, and surface-modified polymers. Projects usually involve one or more external researchers visiting the SHaRE Facility for up to three weeks during the fiscal year (October 1 - September 30). Project approval is based upon the scientific excellence and relevance of proposed collaborative research.

scholarly journals Analysis of Homogeneous Charge Compression Ignition (HCCI) Engines for Cogeneration Applications

2005 ◽  
Vol 128 (1) ◽  
pp. 16-27 ◽  
Author(s):  
Salvador M. Aceves ◽  
Joel Martinez-Frias ◽  
Gordon M. Reistad
Keyword(s):  
Diesel Engines ◽  
High Efficiency ◽  
Homogeneous Charge Compression Ignition ◽  
Utilization Efficiency ◽  
Small Scale ◽  
Compression Ignition ◽  
Hcci Engines ◽  
Si Engines ◽  
Prime Movers ◽  
Homogeneous Charge

This paper presents an evaluation of the applicability of homogeneous charge compression ignition (HCCI) engines for small-scale cogeneration (<1MWe) in comparison to five previously analyzed prime movers. The five comparator prime movers include stoichiometric spark-ignited (SI) engines, lean burn SI engines, diesel engines, microturbines, and fuel cells. The investigated option, HCCI engines, is a relatively new type of engine that has some fundamental differences with respect to other prime movers. The prime movers are compared by calculating electric and heating efficiency, fuel consumption, nitrogen oxide (NOx) emissions, and capital and fuel costs. Two cases are analyzed. In case 1, the cogeneration facility requires combined power and heating. In case 2, the requirement is for power and chilling. The results show that HCCI engines closely approach the very high fuel utilization efficiency of diesel engines without the high emissions of NOx and the expensive diesel fuel. HCCI engines offer a new alternative for cogeneration that provides a combination of low cost, high efficiency, low emissions, and flexibility in operating temperatures that can be optimally tuned for cogeneration systems. HCCI is the most efficient engine technology that meets the strict 2007 CARB NOx standards for cogeneration engines, and merits more detailed analysis and experimental demonstration.

DOE FE Distributed Generation Program

2004 ◽  
Vol 1 (1) ◽  
pp. 18-20 ◽  
Author(s):  
Mark C. Williams ◽  
Bruce R. Utz ◽  
Kevin M. Moore
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Distributed Generation ◽  
High Efficiency ◽  
High Reliability ◽  
National Laboratory ◽  
Pacific Northwest National Laboratory ◽  
Hydrogen Economy ◽  
Wide Range ◽  
The U.S

The U.S. Department of Energy’s (DOE) Office of Fossil Energy’s (FE) National Energy Technology Laboratory (NETL), in partnership with private industries, is leading the development and demonstration of high efficiency solid oxide fuel cells (SOFCs) and fuel cell turbine hybrid power generation systems for near term distributed generation (DG) markets with an emphasis on premium power and high reliability. NETL is partnering with Pacific Northwest National Laboratory (PNNL) in developing new directions in research under the Solid-State Energy Conversion Alliance (SECA) initiative for the development and commercialization of modular, low cost, and fuel flexible SOFC systems. The SECA initiative, through advanced materials, processing and system integration research and development, will bring the fuel cell cost to $400 per kilowatt (kW) for stationary and auxiliary power unit (APU) markets. The President of the U.S. has launched us into a new hydrogen economy. The logic of a hydrogen economy is compelling. The movement to a hydrogen economy will accomplish several strategic goals. The U.S. can use its own domestic resources—solar, wind, hydro, and coal. The U.S. uses 20 percent of the world’s oil but has only 3 percent of resources. Also, the U.S. can reduce green house gas emissions. Clear Skies and Climate Change initiatives aim to reduce carbon dioxide (CO2), nitrogen oxides (NOx), and sulfur dioxide (SO2) emissions. SOFCs have no emissions, so they figure significantly in these DOE strategies. In addition, DG—SOFCs, reforming, energy storage—has significant benefit for enhanced security and reliability. The use of fuel cells in cars is expected to bring about the hydrogen economy. However, commercialization of fuel cells is expected to proceed first through portable and stationary applications. This logic says to develop SOFCs for a wide range of stationary and APU applications, initially for conventional fuels, then switch to hydrogen. Like all fuel cells, the SOFC will operate even better on hydrogen than conventional fuels. The SOFC hybrid is a key part of the FutureGen plants. FutureGen is a major new Presidential initiative to produce hydrogen from coal. The highly efficient SOFC hybrid plant will produce electric power and other parts of the plant could produce hydrogen and sequester CO2. The hydrogen produced can be used in fuel cell cars and for SOFC DG applications.

scholarly journals Design and Initial Development of Monolithic Cross-Flow Ceramic Hot-Gas Filters

1999 ◽  
Author(s):  
Virginie Vaubert ◽  
David P. Stinton ◽  
Chris Barra ◽  
Santosh Limaye
Keyword(s):  
Power Generation ◽  
High Efficiency ◽  
Low Cost ◽  
National Laboratory ◽  
Cross Flow ◽  
Combined Cycle ◽  
Fluidized Bed Combustion ◽  
Initial Development ◽  
Oak Ridge ◽  
Hot Gas

Advanced, coal-fueled, power generation systems utilizing pressurized fluidized bed combustion (PFBC) and integrated gasification combined cycle (IGCC) technologies are currently being developed for high-efficiency, low emissions, and low-cost power generation. In spite of the advantages of these promising technologies, the severe operating environment often leads to material degradation and loss of performance in the barrier filters used for particle entrapment. To address this problem, LoTEC Inc., and Oak Ridge National Laboratory are jointly designing and developing a monolithic cross-flow ceramic hot-gas filter. The filter concept involves a truly monolithic cross-flow design that is resistant to delamination, can be easily fabricated, and offers flexibility of geometry and material make-up. During Phase I of the program, a thermo-mechanical analysis was performed to determine how a cross-flow filter would respond both thermally and mechanically to a series of thermal and mechanical loads. The cross-flow filter mold was designed accordingly, and the materials selection was narrowed down to Ca0.5Sr0.5Zr4P6O24 (CS-50) and 2Al2O3−3SiO2 (mullite). A fabrication process was developed using gelcasting technology and monolithic cross-flow filters were fabricated. The program focuses on obtaining optimum filter permeability and testing the corrosion resistance of the candidate materials.

The Dimension Match and Parameters Setting of the Hydraulic Motor for the Hydraulic-Electromagnetic Energy-Regenerative Shock Absorber

2017 ◽  
Author(s):  
Jia Mi ◽  
Lin Xu ◽  
Sijing Guo ◽  
Mohamed A. A. Abdelkareem ◽  
Lingshuai Meng ◽  
...  
Keyword(s):  
Energy Conversion ◽  
Shock Absorber ◽  
High Efficiency ◽  
Mechanical Energy ◽  
Hydraulic Cylinder ◽  
Electromagnetic Energy ◽  
Operating Conditions ◽  
Hydraulic Motor ◽  
Wide Range ◽  
Regenerative Shock Absorber

Hydraulic-electromagnetic Energy-regenerative Shock Absorber (HESA) has been proposed recently, with the purpose of mitigating vibration in vehicle suspensions and recovering vibration energy traditionally dissipated by oil dampers simultaneously. The HESA is composed of hydraulic cylinder, check valves, accumulators, hydraulic motor, generator, pipelines and so on. The energy conversion from hydraulic energy to mechanical energy mainly depends on the hydraulic motor between two accumulators. Hence, the dimension match and parameter settings of hydraulic motor for the HESA are extremely important for efficiency of the whole system. This paper studies the methods and steps for dimension matching and parameter settings of the hydraulic motor in a case of a typical commercial vehicle. To evaluate suspension’s vibration characteristics, experiments on the target tour bus have been done. Simulations are conducted to investigate the effects of the hydraulic motor in different working conditions. The simulation results verify that the methods and steps adopted are accurate over a wide range of operating conditions and also show that appropriate matching and parameter settings of the hydraulic motor attached in the HESA can work with high efficiency and then effectively improving energy conversion efficiency for the whole system. Therefore, the theory of the matching progress can guide the future design of an HESA.

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