Numerical Investigation of the Impact of Spray – Bowl Interaction on Thermal Efficiency of a Gasoline Compression Ignition Engine

2021 ◽  
Author(s):  
Srinivasa Krishna Addepalli ◽  
Michael Pamminger ◽  
Riccardo Scarcelli ◽  
Thomas Wallner
Keyword(s):  
Thermal Efficiency ◽  
Fuel Injection ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Design Parameters ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Baseline Design ◽  
Piston Bowl ◽  
The Impact

Abstract Gasoline compression ignition (GCI) is a promising way to achieve high thermal efficiency and low emissions while leveraging conventional diesel engine hardware. GCI is a partially premixed combustion concept, which derives its superiority from good volatility and long ignition delay of gasoline-like fuels. The present study investigates the interaction between the piston bowl and the spray plume of a compression ignition engine that operates with a late fuel injection strategy using computational fluid dynamics (CFD) analysis. Simulations were carried out on a single cylinder of a multi-cylinder heavy-duty compression ignition engine. The engine operates at a speed of 1038 rev/min., and a compression ratio of 17. Incylinder turbulence was modelled using RNG k-ε model and the fuel spray break up was modelled using KH-RT model. A reduced chemical kinetic mechanism was used to model combustion chemistry. After validating the combustion and performance characteristics of the baseline piston against experimental results, several new piston bowl designs were generated using CAESES. Full cycle engine simulations for four selected bowl profiles were carried out. The results compare the spray-bowl interaction of the new piston bowl designs with the baseline design. It was found that the lip location and center depth of the bowl profile are the critical design parameters that influence the air utilization and heat transfer losses. The impact of spray-bowl interaction on thermal efficiency of the engine is investigated.

Predicted Qualitative Effects of Alternate Liquid Fuels on Heavy-Duty Compression-Ignition Engines

2009 ◽  
Author(s):  
Gong Chen
Keyword(s):  
Fuel Injection ◽  
Cetane Number ◽  
Fuel Properties ◽  
Liquid Fuels ◽  
Compression Ignition ◽  
Heavy Duty ◽  
Compression Ignition Engine ◽  
End Effects ◽  
Compression Ignition Engines ◽  
The Impact

It is always desirable for a heavy-duty compression-ignition engine, such as a diesel engine, to possess a capability of using alternate liquid fuels without significant hardware modification to the engine baseline. Because fuel properties vary between various types of liquid fuels, it is important to understand the impact and effects of the fuel properties on engine operating and output parameters. This paper intends and attempts to achieve that understanding and to predict the qualitative effects by studying analytically and qualitatively how a heavy-duty compression-ignition engine would respond to the variation of fuel properties. The fuel properties considered in this paper mainly include the fuel density, compressibility, heating value, viscosity, cetane number, and distillation temperature range. The qualitative direct and end effects of the fuel properties on engine bulk fuel injection, in-cylinder combustion, and outputs are analyzed and predicted. Understanding these effects can be useful in analyzing and designing a compression-ignition engine for using alternate liquid fuels.

Analysis of Compression-Ignition Engine Design Concerning Engine Structural Loading Capacity

2004 ◽  
Author(s):  
Gong Chen
Keyword(s):  
Thermal Loading ◽  
Fuel Injection ◽  
Fuel Efficiency ◽  
Design Parameters ◽  
Analytical Prediction ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Exhaust Temperature ◽  
High Fuel Efficiency ◽  
Structural Loading

Present-day high-power compression-ignition engines are required in design not only to achieve a targeted high fuel efficiency, but also to meet regulated exhaust emissions standards. This paper investigates the effects of the in-cylinder combustion related design parameters, including cylinder compression ratio, fuel injection-start timing, and the amount of cylinder air charge, on engine performances and emissions as the engine structure-loading allowance is specified. Thereby the determination of those parameters to optimize the engine overall performances without exceeding the allowances in engine mechanical and thermal loading can be achieved. An enhanced understanding of those design parameters associated with the engine structural loading parameters, such as the cylinder peak firing pressure and exhaust temperature, is studied. The analytical prediction of the trade-off between those parameters with peak firing pressure contained is modeled and developed.

Numerical assessment of ozone addition potential in direct injection compression ignition engines

2020 ◽  
pp. 146808742097355
Author(s):  
Vincent Giuffrida ◽  
Michele Bardi ◽  
Mickael Matrat ◽  
Anthony Robert ◽  
Guillaume Pilla
Keyword(s):  
Cfd Simulation ◽  
Fuel Injection ◽  
Direct Injection ◽  
High Reactivity ◽  
Experimental Results ◽  
Injection Timing ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Compression Stroke ◽  
The Impact

This paper aims at taking into account the chemistry of O3 in a 3D CFD simulation of compression ignition engine with Diesel type combustion for low load operating points. The methodology developed in this work includes 0D homogeneous reactors simulations, 3D RANS simulations and validation regarding experimental results. The 0D simulations were needed to take into account O3 reactions during the compression stroke because of the high reactivity of O3 with NO and dissociation at high temperature. The values found in these simulations were used as an input in the 3D model to match the correct O3 concentration at fuel injection timing. The 3D simulations were performed using CONVERGETM with a RANS approach. Simulations reproduce the compression/expansion stroke after the intake valve closure to focus on the impact of O3 on the fuel auto ignition. The comparison between numerical and experimental results demonstrates that the proposed methodology is able to capture correctly the impact of O3 addition on ignition delay and on heat release. Moreover, the analysis of the data enables to better understand the fundamental processes driving O3 impact in a CI engine. In particular, using 0D simulations, the plateau effect observed experimentally when increasing O3 concentration is attributed to O3 thermal decomposition and reaction with NO during the compression stroke. Also, 3D CFD results showed that O3 impact is observed mainly during LTHR phase and does not affect the topology and the propagation of the flame inside the combustion chamber.

CFD Simulation of Gasoline Compression Ignition

2014 ◽  
Author(s):  
Janardhan Kodavasal ◽  
Christopher Kolodziej ◽  
Stephen Ciatti ◽  
Sibendu Som
Keyword(s):  
Turbulence Model ◽  
Cfd Simulation ◽  
Turbulence Models ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Combustion Model ◽  
Low Temperature Combustion ◽  
Compression Ignition ◽  
Simulation Results ◽  
The Impact

Gasoline compression ignition (GCI) is a low temperature combustion (LTC) concept that has been gaining increasing interest over the recent years owing to its potential to achieve diesel-like thermal efficiencies with significantly reduced engine-out nitrogen oxides (NOx) and soot emissions compared to diesel engines. In this work, closed-cycle computational fluid dynamics (CFD) simulations are performed of this combustion mode using a sector mesh in an effort to understand effects of model settings on simulation results. One goal of this work is to provide recommendations for grid resolution, combustion model, chemical kinetic mechanism, and turbulence model to accurately capture experimental combustion characteristics. Grid resolutions ranging from 0.7 mm to 0.1 mm minimum cell sizes were evaluated in conjunction with both Reynolds averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) based turbulence models. Solution of chemical kinetics using the multi-zone approach is evaluated against the detailed approach of solving chemistry in every cell. The relatively small primary reference fuel (PRF) mechanism (48 species) used in this study is also evaluated against a larger 312-species gasoline mechanism. Based on these studies the following model settings are chosen keeping in mind both accuracy and computation costs — 0.175 mm minimum cell size grid, RANS turbulence model, 48-species PRF mechanism, and multi-zone chemistry solution with bin limits of 5 K in temperature and 0.05 in equivalence ratio. With these settings, the performance of the CFD model is evaluated against experimental results corresponding to a low load start of injection (SOI) timing sweep. The model is then exercised to investigate the effect of SOI on combustion phasing with constant intake valve closing (IVC) conditions and fueling over a range of SOI timings to isolate the impact of SOI on charge preparation and ignition. Simulation results indicate that there is an optimum SOI timing, in this case −30°aTDC (after top dead center), which results in the most stable combustion. Advancing injection with respect to this point leads to significant fuel mass burning in the colder squish region, leading to retarded phasing and ultimately misfire for SOI timings earlier than −42°aTDC. On the other hand, retarding injection beyond this optimum timing results in reduced residence time available for gasoline ignition kinetics, and also leads to retarded phasing, with misfire at SOI timings later than −15°aTDC.

Experimental Investigation of Direct Fuel Injection into Low-Oxygen Recompression Interval in a Homogenous Charge Compression Ignition Engine

2021 ◽  
pp. 1-25
Author(s):  
Ratnak Sok ◽  
Jin Kusaka
Keyword(s):  
Thermal Efficiency ◽  
Fuel Injection ◽  
Pressure Rise ◽  
Operating Conditions ◽  
Combustion Noise ◽  
Maximum Pressure ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Single Digit ◽  
Homogenous Charge Compression Ignition

Abstract This work analyzed measured data from a single-cylinder engine operated under gasoline direction injection homogenous charge compression ignition (GDI-HCCI) mode. The experiments were conducted at a 0.95 equivalence ratio (φ) under 0.5 MPa indicated mean effective pressure and 1500RPM. A side-mounted injector delivered primary reference fuel (octane number 90) into the combustion chamber during negative valve overlap (NVO). Advanced combustion phase CA50 were observed as a function of the start of injection (SOI) timings. Under φ=0.95, peak NVO in-cylinder pressures were lower than motoring for single and split injections, emphasizing that NVO reactions were endothermic. Zero-dimensional kinetics calculations showed classical reformate species (C3H6, C2H4, CH4) from the NVO rich mixture increased almost linearly due to SOI timings, while H2 and CO were typically low. These kinetically reformed species shortened predicted ignition delays. This work also analyzed the effects of intake pressure and single versus double pulses injections on CA50, burn duration, peak cylinder pressure, combustion noise, thermal efficiency, and emissions. Advanced SOI (single-injection) generated excessive combustion noise metrics over constraint limits, but the double-pulse injection could significantly reduce the metrics (Ringing Intensity ≤ 5 MW/m2, Maximum Pressure Rise Rate = 0.6 MPa/CA) and NOx emission. The engine's net indicated thermal efficiency reached 41% under GDI-HCCI mode against 36% under SI mode for the same operating conditions. Under GDI-HCCI mode and without spark-ignition, late fuel injection in the intake stroke could reduce NOx to a single digit.

Engine performance and emission characteristics of a compression ignition engine fuelled with diesel/dimethoxymethane blends

2005 ◽  
Vol 219 (7) ◽  
pp. 905-914 ◽  
Author(s):  
Y Ren ◽  
Z H Huang ◽  
D M Jiang ◽  
L X Liu ◽  
K Zeng ◽  
...  
Keyword(s):  
Thermal Efficiency ◽  
Mass Fraction ◽  
Volume Fraction ◽  
Engine Performance ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Performance And Emission ◽  
Fuel Blends ◽  
Performance And Emissions ◽  
Combustion Phase

The performance and emissions of a compression ignition engine fuelled with diesel/dimethoxymethane (DMM) blends were studied. The results showed that the engine's thermal efficiency increased and the diesel equivalent brake specific fuel consumption (b.s.f.c.) decreased as the oxygen mass fraction (or DMM mass fraction) of the diesel/DMM blends increased. This change in the diesel/DMM blends was caused by an increased fraction of the premixed combustion phase, an oxygen enrichment, and an improvement in the diffusive combustion phase. A remarkable reduction in the exhaust CO and smoke can be achieved when operating on the diesel/DMM blend. Flat NO x/smoke and thermal efficiency/smoke curves are presented when operating on the diesel/DMM fuel blends, and a simultaneous reduction in both NO x and smoke can be realized at large DMM addition. Thermal efficiency and NO x give the highest value at 2 per cent oxygen mass fraction (or 5 per cent DMM volume fraction) for the combustion of diesel/DMM blends.

Influence of Various Basin Types on Performance of Passive Solar Still: A Review

2021 ◽  
Vol 10 (4) ◽  
pp. 789-802
Author(s):  
Tri Hieu Le ◽  
Minh Tuan Pham ◽  
H Hadiyanto ◽  
Van Viet Pham ◽  
Anh Tuan Hoang
Keyword(s):  
Water Depth ◽  
Thermal Efficiency ◽  
Tracking System ◽  
Design Parameters ◽  
Cylindrical Shape ◽  
Solar Still ◽  
Practical Utilization ◽  
Passive Solar Still ◽  
Passive Solar ◽  
The Impact

Passive solar still is the simplest design for distilling seawater by harnessing solar energy. Although it is undeniable that solar still is a promising device to provide an additional freshwater source for global increasing water demand, low thermal efficiency along with daily distillate yield are its major disadvantages. A conventional solar still can produced 2 to 5 L/m2day. Various studies have been carried out to improve passive solar stills in terms of daily productivity, thermal efficiency, and economic effectiveness. Most of the researches that relate to the daily output improvement of passive solar still concentrates on enhancing evaporation or/and condensation processes. While the condensation process is influenced by wind velocity and characteristics of the condensed surface, the evaporation process is mainly affected by the temperature of basin water. Different parameters affect the brackish water temperature such as solar radiation, design parameters (for example water depth, insulators, basin liner absorptivity, reflectors, sun tracking system, etc). The inclined angle of the top cover is suggested to equal the latitude of the experimental place. Moreover, the decrease of water depth was obtained as a good operational parameter, however, the shallow water depth is required additional feed water for ensuring no dry spot existence. Reflectors and sun-tracking systems help solar still absorb as much solar intensity as possible. The internal reflector can enhance daily yield and efficiency of stepped solar still up to 75% and 56% respectively, whereas, passive solar still with the support of a sun-tracking system improved daily yield up to 22%. Despite large efforts to investigate the impact of the different parameters on passive solar distillation, the effect of the basin liner (including appropriate shapes and type of material), needs to be analyzed for improvement in practical utilization. The present work has reviewed the investigation of the solar still performance with various types of basin liner. The review of solar stills has been conducted critically with rectangular basin, fins basin, corrugated basin, wick type, steps shape, and cylindrical shape basin with variety of top cover shapes. The findings from this work conclude that the basin liner with a cylindrical shape had better performance in comparison with other metal types and provides higher freshwater output. Stepped type, inclined, fin absorber, and corrugated shapes had the efficient performance.  Further exploration revealed that copper is the best-used material for the productivity of passive solar still.

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