The Effects of High-Pressure Injection on a Compression–Ignition, Direct Injection of Natural Gas Engine

2006 ◽  
Vol 129 (2) ◽  
pp. 579-588 ◽  
Author(s):  
G. P. McTaggart-Cowan ◽  
H. L. Jones ◽  
S. N. Rogak ◽  
W. K. Bushe ◽  
P. G. Hill ◽  
...  

This study investigated the effects of injection pressure on the performance and emissions of a pilot-ignited, late-cycle direct-injected natural gas fueled heavy-duty engine. The experiments, conducted on a single-cylinder engine, covered a wide range of engine speeds, loads, and exhaust gas recirculation fractions. The injection pressure was varied at each operating condition while all other parameters were held constant. At high loads, increasing the injection pressure substantially reduced particulate matter and CO emissions, with small increases in NOx and no significant effect on hydrocarbon emissions or fuel consumption. At low loads, injection pressure had no significant impact on either emissions or performance. At high loads, higher injection pressures consistently reduced both the number density and the size of particles in the exhaust stream. Injection pressure had reduced effects at increased engine speeds.

Author(s):  
C. M. Gibson ◽  
A. C. Polk ◽  
N. T. Shoemaker ◽  
K. K. Srinivasan ◽  
S. R. Krishnan

With increasingly restrictive NOx and particulate matter emissions standards, the recent discovery of new natural gas reserves, and the possibility of producing propane efficiently from biomass sources, dual fueling strategies have become more attractive. This paper presents experimental results from dual fuel operation of a four-cylinder turbocharged direct injection (DI) diesel engine with propane or methane (a natural gas surrogate) as the primary fuel and diesel as the ignition source. Experiments were performed with the stock engine control unit at a constant speed of 1800 rpm, and a wide range of brake mean effective pressures (BMEPs) (2.7–11.6 bars) and percent energy substitutions (PESs) of C3H8 and CH4. Brake thermal efficiencies (BTEs) and emissions (NOx, smoke, total hydrocarbons (THCs), CO, and CO2) were measured. Maximum PES levels of about 80–95% with CH4 and 40–92% with C3H8 were achieved. Maximum PES was limited by poor combustion efficiencies and engine misfire at low loads for both C3H8 and CH4, and the onset of knock above 9 bar BMEP for C3H8. While dual fuel BTEs were lower than straight diesel BTEs at low loads, they approached diesel BTE values at high loads. For dual fuel operation, NOx and smoke reductions (from diesel values) were as high as 66–68% and 97%, respectively, but CO and THC emissions were significantly higher with increasing PES at all engine loads.


Author(s):  
C. M. Gibson ◽  
A. C. Polk ◽  
N. T. Shoemaker ◽  
K. K. Srinivasan ◽  
S. R. Krishnan

With increasingly restrictive NOx and PM emissions standards, the recent discovery of new natural gas reserves, and the possibility of producing propane efficiently from biomass sources, dual fueling strategies have become more attractive. This paper presents experimental results from dual-fueling a four-cylinder turbocharged DI diesel engine with propane or methane (a natural gas surrogate) as the primary fuel and diesel as the ignition source. Experiments were performed with the stock ECU at a constant speed of 1800 rev/min, and a wide range of BMEPs (2.7 to 11.6 bar) and percent energy substitutions (PES) of C3H8 and CH4. Brake thermal efficiencies (BTE) and emissions (NOx, smoke, THC, CO, and CO2) were measured. Maximum PES levels of about 80–95 percent with CH4 and 40–92 percent with C3H8 were achieved. Maximum PES was limited by poor combustion efficiencies and engine misfire at low loads for both C3H8 and CH4, and the onset of knock above 9 bar BMEP for C3H8. While dual fueling BTEs were lower than straight diesel BTEs at low loads, they approached diesel BTE values at high loads. With dual fueling, NOx and smoke reductions (from diesel values) were as high as 66–68 percent and 97 percent, respectively, but CO and THC emissions were significantly higher with increasing PES at all engine loads.


Author(s):  
Menghan Li ◽  
Qiang Zhang ◽  
Guoxiang Li

In this paper, the effects of the injection timing, the injection pressure and the engine load on the combustion noise of a pilot-ignited direct-injection natural-gas engine were explored by analysing the separate components of the in-cylinder pressure. The results suggested that retarding the injection timing and reducing the injection pressure are effective ways of controlling the combustion noise. This can be attributed to the promoted burning rate at advanced injection timings and to the increased injection pressure. However, the effect of the engine load seems to be less obvious, although the resonance pressure level appears to increase with increasing engine load; the estimated combustion noise shows a decreasing tendency.


2017 ◽  
Vol 19 (3) ◽  
pp. 347-359 ◽  
Author(s):  
Felix Leach ◽  
Richard Stone ◽  
Dave Richardson ◽  
Andrew Lewis ◽  
Sam Akehurst ◽  
...  

Downsized, highly boosted, gasoline direct injection engines are becoming the preferred gasoline engine technology to ensure that increasingly stringent fuel economy and emissions legislation are met. The Ultraboost project engine is a 2.0-L in-line four-cylinder prototype engine, designed to have the same performance as a 5.0-L V8 naturally aspirated engine but with reduced fuel consumption. It is important to examine particle number emissions from such extremely highly boosted engines to ensure that they are capable of meeting current and future emissions legislation. The effect of such high boosting on particle number emissions is reported in this article for a variety of operating points and engine operating parameters. The effect of engine load, air–fuel ratio, fuel injection pressure, fuel injection timing, ignition timing, inlet air temperature, exhaust gas recirculation level, and exhaust back pressure has been investigated. It is shown that particle number emissions increase with increase in cooled, external exhaust gas recirculation and engine load, and decrease with increase in fuel injection pressure and inlet air temperature. Particle number emissions are shown to fall with increased exhaust back pressure, a key parameter for highly boosted engines. The effects of these parameters on the particle size distributions from the engine have also been evaluated. Significant changes to the particle size spectrum emitted from the engine are seen depending on the engine operating point. Operating points with a bias towards very small particle sizes were noted.


Author(s):  
Zhang Ming ◽  
Zhong Jun ◽  
Capelli Stefano ◽  
Lubrano Luigi

The development process of a down-sized turbocharged gasoline direct-injection (GDI) engine/vehicle was partially introduced with the focus on particulate matter (PM)/particle number (PN) emission reduction. To achieve this goal, the injection system was upgraded to obtain higher injection pressure. Two types of prototype injectors were designed and compared under critical test conditions. Combined numerical and experimental analysis was made to select the right injector in terms of particle emission. With the selected injector, the effect of injection parameters calibration (injection pressure, start of injection (SOI) timing, number of injection pulses, etc.) on PM/PN emission was illustrated. The number of fuel injection pulses, SOI timing, and injection pressure were found playing the leading role in terms of the particle emission suppression. With single-injection strategy, the injection pressure and SOI timing were found to be a dominant factor to reduce particle emission in warm-up condition and cold condition, respectively; a fine combination of injection timing and injection pressure is generally able to decrease up to 50% of PM emission in a wide range of the engine map. While with multiple injection, up to an order of magnitude PM emission reduction can be achieved. Several New European Driving Cycle (NEDC) emission cycles were arranged on a demo vehicle to evaluate the effect of the injection system upgrade and adjusted calibration. This work will provide a guide for the emission control of GDI engines/vehicles fulfilling future emission legislation.


2000 ◽  
Author(s):  
Fabio Bozza ◽  
Maria Cristina Cameretti ◽  
Antonio Marro ◽  
Raffaele Tuccillo

Abstract The authors present a methodology for the prediction of performance and emissions of a gas turbine under a wide range of load conditions. The engine, of the aero-derivative type, is employed in a natural gas recompression plant. The paper deals, in its first part, with the reconstruction of the whole operating region of both the gas generator set and the power turbine including its matching with the centrifugal compressor for natural gas delivery in the pipeline. This phase also leads to an effective prediction of pollutant emission, with a chemical kinetics based sub-model. Next, a refined CFD based simulation analyzes a number of operating cases, so providing a detailed insight of the actual phenomena which control the combustion chamber temperature distribution and the activation of the pollutant formation mechanisms.


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