scholarly journals Spray-Wall Interactions in a Small-Bore, Multi-Cylinder Engine Operating With Reactivity-Controlled Compression Ignition

2017 ◽  
Author(s):  
Martin L. Wissink ◽  
Scott J. Curran ◽  
Chaitanya Kavuri ◽  
Sage L. Kokjohn
Keyword(s):  
Compression Ignition ◽  
Compelling Evidence ◽  
Cfd Simulations ◽  
Fuel Film ◽  
Reactivity Controlled Compression Ignition ◽  
Spray Penetration ◽  
Crank Angle ◽  
Computational Fluid Dynamics Cfd ◽  
Wall Interactions ◽  
Early Injection

Experimental work on reactivity-controlled compression ignition (RCCI) in a small-bore, multi-cylinder engine operating on premixed iso-octane and direct-injected n-heptane has shown an unexpected combustion phasing advance at early injection timings, which has not been observed in large-bore engines operating under RCCI at similar conditions. In this work, computational fluid dynamics (CFD) simulations were performed to investigate whether spray-wall interactions could be responsible for this result. Comparison of the spray penetration, fuel film mass, and in-cylinder visualization of the spray from the CFD results to the experimentally measured combustion phasing and emissions provided compelling evidence of strong fuel impingement at injection timings earlier than −90 crank angle degrees (°CA) after top dead center (aTDC), and transition from partial to full impingement between −65 and −90°CA aTDC. Based on this evidence, explanations for the combustion phasing advance at early injection timings are proposed along with potential verification experiments.

scholarly journals Spray–Wall Interactions in a Small-Bore, Multicylinder Engine Operating With Reactivity-Controlled Compression Ignition

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Martin L. Wissink ◽  
Scott J. Curran ◽  
Chaitanya Kavuri ◽  
Sage L. Kokjohn
Keyword(s):  
Compression Ignition ◽  
Compelling Evidence ◽  
Cfd Simulations ◽  
Fuel Film ◽  
Reactivity Controlled Compression Ignition ◽  
Spray Penetration ◽  
Crank Angle ◽  
Computational Fluid Dynamics Cfd ◽  
Wall Interactions ◽  
Early Injection

Experimental work on reactivity-controlled compression ignition (RCCI) in a small-bore, multicylinder engine operating on premixed iso-octane, and direct-injected n-heptane has shown an unexpected combustion phasing advance at early injection timings, which has not been observed in large-bore engines operating under RCCI at similar conditions. In this work, computational fluid dynamics (CFD) simulations were performed to investigate whether spray–wall interactions could be responsible for this result. Comparison of the spray penetration, fuel film mass, and in-cylinder visualization of the spray from the CFD results to the experimentally measured combustion phasing and emissions provided compelling evidence of strong fuel impingement at injection timings earlier than −90 crank angle degrees (deg CA) after top dead center (aTDC), and transition from partial to full impingement between −65 and −90 deg CA aTDC. Based on this evidence, explanations for the combustion phasing advance at early injection timings are proposed along with potential verification experiments.

Comparisons of particle size distribution from conventional and advanced compression ignition combustion strategies

2017 ◽  
Vol 19 (7) ◽  
pp. 699-717 ◽  
Author(s):  
Yizhou Zhang ◽  
Jaal Ghandhi ◽  
David Rothamer
Keyword(s):  
Particle Size ◽  
Natural Gas ◽  
Size Distribution ◽  
Homogeneous Charge Compression Ignition ◽  
Compression Ignition ◽  
Reactivity Controlled Compression Ignition ◽  
Advanced Combustion ◽  
Particulate Size ◽  
Early Injection ◽  
Homogeneous Charge

Particulate size distribution measurements are of importance in engine research as stricter regulations on particulate matter emissions (both mass and number based) are being implemented. Particulate size distribution measurements can be very sensitive to the laboratory environment or experimental setup, making it difficult to compare results for different combustion strategies acquired in different labs. In this study, a comparison of particulate size distribution measurements over a wide variety of conventional and advanced combustion strategies was conducted using a four-stroke single-cylinder diesel engine test setup to eliminate lab-to-lab variations and enable direct comparison of particulate size distribution results for different combustion strategies. Eight combustion strategies are included in the comparison: conventional diesel combustion, diesel/gasoline reactivity controlled compression ignition, homogeneous charge compression ignition, two types of gasoline compression ignition (early injection and late injection), diesel low temperature combustion, natural gas combustion with diesel pilot injection, and diesel/natural gas reactivity controlled compression ignition. Measurements were performed at four different load-speed points with matched combustion phasing when possible; for several strategies, it was necessary to operate with slightly different combustion phasing. Particle size distributions were measured using a scanning mobility particle sizer. To study the influence of volatile particles, measurements were performed with and without a volatile particle remover (thermodenuder) at low and high dilution ratios. The results show that non-uniformity in the fuel distribution caused by direct injection results in increased accumulation-mode particle concentrations compared to premixed strategies even for low particulate mass advanced combustion strategies. Premixed combustion strategies (homogeneous charge compression ignition) and early injection gasoline compression ignition show higher nuclei-mode particle concentrations. Overall particle number and mass concentrations vary significantly between engine operating conditions and between combustion strategies.

Development of a Stiffness-Based Chemistry Load Balancing Scheme, and Optimization of Input/Output and Communication, to Enable Massively Parallel High-Fidelity Internal Combustion Engine Simulations

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Janardhan Kodavasal ◽  
Kevin Harms ◽  
Priyesh Srivastava ◽  
Sibendu Som ◽  
Shaoping Quan ◽  
...  
Keyword(s):  
Load Balancing ◽  
Combustion Engine ◽  
Mesh Size ◽  
Test Case ◽  
Compression Ignition ◽  
Input Output ◽  
Engine Simulation ◽  
Crank Angle ◽  
Computational Fluid Dynamics Cfd ◽  
Blue Gene

A closed-cycle gasoline compression ignition (GCI) engine simulation near top dead center (TDC) was used to profile the performance of a parallel commercial engine computational fluid dynamics (CFD) code, as it was scaled on up to 4096 cores of an IBM Blue Gene/Q (BG/Q) supercomputer. The test case has 9 × 106 cells near TDC, with a fixed mesh size of 0.15 mm, and was run on configurations ranging from 128 to 4096 cores. Profiling was done for a small duration of 0.11 crank angle degrees near TDC during ignition. Optimization of input/output (I/O) performance resulted in a significant speedup in reading restart files, and in an over 100-times speedup in writing restart files and files for postprocessing. Improvements to communication resulted in a 1400-times speedup in the mesh load balancing operation during initialization, on 4096 cores. An improved, “stiffness-based” algorithm for load balancing chemical kinetics calculations was developed, which results in an over three-times faster runtime near ignition on 4096 cores relative to the original load balancing scheme. With this improvement to load balancing, the code achieves over 78% scaling efficiency on 2048 cores, and over 65% scaling efficiency on 4096 cores, relative to 256 cores.

scholarly journals An Experimental Investigation on the Influence of Port Injection at Valve on Combustion and Emission Characteristics of B5/Biogas RCCI Engine

2020 ◽  
Vol 10 (2) ◽  
pp. 452
Author(s):  
Ibrahim B. Dalha ◽  
Mior A. Said ◽  
Zainal A. Abdul Karim ◽  
Salah E. Mohammed
Keyword(s):  
Fuel Mixture ◽  
Injection Timing ◽  
Compression Ignition ◽  
Reactivity Controlled Compression Ignition ◽  
Indicated Mean Effective Pressure ◽  
Unburned Hydrocarbon ◽  
Crank Angle ◽  
Slow Combustion ◽  
Low Load ◽  
Co Emission

High unburned hydrocarbon (UHC) and carbon monoxide (CO) emissions, on account of the premixed air-fuel mixture entering the crevices and pre-mature combustion, are setbacks to reactivity-controlled compression ignition (RCCI) combustion at a low load. The influence of direct-injected B5 and port injection of biogas at the intake valve was, experimentally, examined in the RCCI mode. The port injection at the valve was to elevate the temperature at low load and eliminate premixing for reduced pre-mature combustion and fuel entering the crevices. An advanced injection timing of 21° crank angle before top dead centre and fraction of 50% each of the fuels, were maintained at speeds of 1600, 1800 and 2000 rpm and varied the load from 4.5 to 6.5 bar indicated mean effective pressure (IMEP). The result shows slow combustion as the load increases with the highest indicated thermal efficiency of 36.33% at 5.5 bar IMEP. The carbon dioxide and nitrogen oxides emissions increased, but UHC emission decreased, significantly, as the load increases. However, CO emission rose from 4.5 to 5.5 bar IMEP, then reduced as the load increases. The use of these fuels and biogas injection at the valve were capable of averagely reducing the persistent challenge of the CO and UHC emissions, by 20.33% and 10% respectively, compared to the conventional premixed mode.

Effect of nitrogen and hydrogen addition on performance and emissions in reactivity controlled compression ignition

Fuel ◽  
2021 ◽  
Vol 292 ◽  
pp. 120330
Author(s):  
Sohayb Bahrami ◽  
Kamran Poorghasemi ◽  
Hamit Solmaz ◽  
Alper Calam ◽  
Duygu İpci
Keyword(s):  
Compression Ignition ◽  
Reactivity Controlled Compression Ignition ◽  
Hydrogen Addition ◽  
Performance And Emissions

scholarly journals Effect of Injection Timing and Injection Duration of Manifold Injected Fuels in Reactivity Controlled Compression Ignition Engine Operated with Renewable Fuels

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4621
Author(s):  
P. A. Harari ◽  
N. R. Banapurmath ◽  
V. S. Yaliwal ◽  
T. M. Yunus Khan ◽  
Irfan Anjum Badruddin ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Injection Timing ◽  
Compression Ignition ◽  
Cylinder Pressure ◽  
Compression Ignition Engine ◽  
Compressed Natural Gas ◽  
Reactivity Controlled Compression Ignition ◽  
Brake Thermal Efficiency ◽  
Injection Duration ◽  
Fuel Mixtures

In the current work, an effort is made to study the influence of injection timing (IT) and injection duration (ID) of manifold injected fuels (MIF) in the reactivity controlled compression ignition (RCCI) engine. Compressed natural gas (CNG) and compressed biogas (CBG) are used as the MIF along with diesel and blends of Thevetia Peruviana methyl ester (TPME) are used as the direct injected fuels (DIF). The ITs of the MIF that were studied includes 45°ATDC, 50°ATDC, and 55°ATDC. Also, present study includes impact of various IDs of the MIF such as 3, 6, and 9 ms on RCCI mode of combustion. The complete experimental work is conducted at 75% of rated power. The results show that among the different ITs studied, the D+CNG mixture exhibits higher brake thermal efficiency (BTE), about 29.32% is observed at 50° ATDC IT, which is about 1.77, 3.58, 5.56, 7.51, and 8.54% higher than D+CBG, B20+CNG, B20+CBG, B100+CNG, and B100+CBG fuel combinations. The highest BTE, about 30.25%, is found for the D+CNG fuel combination at 6 ms ID, which is about 1.69, 3.48, 5.32%, 7.24, and 9.16% higher as compared with the D+CBG, B20+CNG, B20+CBG, B100+CNG, and B100+CBG fuel combinations. At all ITs and IDs, higher emissions of nitric oxide (NOx) along with lower emissions of smoke, carbon monoxide (CO), and hydrocarbon (HC) are found for D+CNG mixture as related to other fuel mixtures. At all ITs and IDs, D+CNG gives higher In-cylinder pressure (ICP) and heat release rate (HRR) as compared with other fuel combinations.

scholarly journals Using CFD to Evaluate Natural Ventilation through a 3D Parametric Modeling Approach

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2197
Author(s):  
Nayara Rodrigues Marques Sakiyama ◽  
Jurgen Frick ◽  
Timea Bejat ◽  
Harald Garrecht
Keyword(s):  
Natural Ventilation ◽  
Parametric Modeling ◽  
Cfd Simulations ◽  
3D Design ◽  
Post Process ◽  
Test House ◽  
Model Set ◽  
Computational Fluid Dynamics Cfd ◽  
Set Up ◽  
Passive Strategy

Predicting building air change rates is a challenge for designers seeking to deal with natural ventilation, a more and more popular passive strategy. Among the methods available for this task, computational fluid dynamics (CFD) appears the most compelling, in ascending use. However, CFD simulations require a range of settings and skills that inhibit its wide application. With the primary goal of providing a pragmatic CFD application to promote wind-driven ventilation assessments at the design phase, this paper presents a study that investigates natural ventilation integrating 3D parametric modeling and CFD. From pre- to post-processing, the workflow addresses all simulation steps: geometry and weather definition, including incident wind directions, a model set up, control, results’ edition, and visualization. Both indoor air velocities and air change rates (ACH) were calculated within the procedure, which used a test house and air measurements as a reference. The study explores alternatives in the 3D design platform’s frame to display and compute ACH and parametrically generate surfaces where air velocities are computed. The paper also discusses the effectiveness of the reference building’s natural ventilation by analyzing the CFD outputs. The proposed approach assists the practical use of CFD by designers, providing detailed information about the numerical model, as well as enabling the means to generate the cases, visualize, and post-process the results.

scholarly journals Dependence of the Flue Gas Flow on the Setting of the Separation Baffle in the Flue Gas Tract

2021 ◽  
Vol 11 (7) ◽  
pp. 2961
Author(s):  
Nikola Čajová Kantová ◽  
Alexander Čaja ◽  
Marek Patsch ◽  
Michal Holubčík ◽  
Peter Ďurčanský
Keyword(s):  
Particulate Matter ◽  
Flue Gas ◽  
Gas Flow ◽  
Negative Impact ◽  
Combustion Process ◽  
Cfd Simulations ◽  
Piv Measurements ◽  
Computational Fluid Dynamics Cfd ◽  
Particle Imaging ◽  
Combustion Of Solid Fuels

With the combustion of solid fuels, emissions such as particulate matter are also formed, which have a negative impact on human health. Reducing their amount in the air can be achieved by optimizing the combustion process as well as the flue gas flow. This article aims to optimize the flue gas tract using separation baffles. This design can make it possible to capture particulate matter by using three baffles and prevent it from escaping into the air in the flue gas. The geometric parameters of the first baffle were changed twice more. The dependence of the flue gas flow on the baffles was first observed by computational fluid dynamics (CFD) simulations and subsequently verified by the particle imaging velocimetry (PIV) method. Based on the CFD results, the most effective is setting 1 with the same boundary conditions as those during experimental PIV measurements. Setting 2 can capture 1.8% less particles and setting 3 can capture 0.6% less particles than setting 1. Based on the stoichiometric calculations, it would be possible to capture up to 62.3% of the particles in setting 1. The velocities comparison obtained from CFD and PIV confirmed the supposed character of the turbulent flow with vortexes appearing in the flue gas tract, despite some inaccuracies.

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