Wide Open Throttle Conditions Research Articles

Effects of compression ratio and hydrogen addition on lean combustion characteristics and emission formation in a Compressed Natural Gas fuelled spark ignition engine

A single cylinder diesel engine was modified to operate as a Compressed Natural Gas (CNG) fuelled lean burn Spark Ignition (SI) engine. The engine was tested at 1500rpm under wide open throttle condition at different compression ratios over varying equivalence ratios. The optimized compression ratio for CNG operation was found to be 12.5:1 which was further investigated for hydrogen substitution at 5% and 10% on energy basis to study and compare the performance, emission and combustion behavior of CNG fuelled lean burn SI engine. The brake thermal efficiency and brake power output increases with rise in compression ratio and achieved a peak brake thermal efficiency of 30.2% with 12.5:1 compression ratio and above a critical value of 12.5:1, the improvement was small when compared to the increase in emissions. Wide flammability limits of hydrogen enable ultra-lean combustion thereby extends the lean limit of operation to an equivalence ratio of 0.42 with 10% hydrogen addition as compared to 0.50 with neat CNG operation and its anti-knock enhancement makes it advantageous compared to increasing the compression ratio under low load conditions. Hydrogen addition also enhanced the combustion rate, heat release rate and reduced cyclic variations. On the emissions front, hydrogen addition showed reduction in hydrocarbon emissions from 65g/kWh to 6.9g/kWh at an equivalence ratio of 0.5 alongside carbon monoxide and carbon dioxide reduction. Due to retarded ignition timing to avoid knock, the Oxides of Nitrogen (NOx) emission increase was not significant.

Cycle by cycle variations of LPG-gasoline dual fuel on a multi-cylinder MPFI gasoline engine

ABSTRACTCombustion stability of a multipoint port fuel injection spark ignition engine working on liquefied petroleum gas (LPG)-gasoline dual fuel mode of operation was analysed. LPG-gasoline ratio was varied from 0 to 100% by controlling the injector signals at wide open throttle condition and 3000 RPM. Increasing LPG ratio will give higher peak pressure and higher indicated mean effective pressure (IMEP) because of the higher flame propagation speed of LPG. The experiment showed that maximum pressure will occur nearer to top dead centre when compared to gasoline. Fluctuation in maximum pressure is higher for LPG and is minimum for 50% LPG. Time return map showed that combustion instabilibity will be more for 100% LPG and is less for 50% LPG. Coefficient of variation of IMEP and maximum pressure for gasoline is higher than LPG. With 100% LPG, NOx emission is almost three times that of gasoline. Hence it can be concluded that 50% LPG will give the better combustion characteristics when compared to other fuel blends.

Effect of flash boiling on microscopic and macroscopic spray characteristics in optical GDI engine

The flash boiling sprays in a single-cylinder optical gasoline direct injection (GDI) engine were studied using phase Doppler particle analyzer (PDPA) and high-speed photography. Initially, the factors which may influence the in-cylinder measurement reliability of PDPA were carefully examined under atmospheric conditions. Afterwards, engine experiments were conducted under idle and wide open throttle (WOT) conditions with the fuel temperature ranging from 20°C to 90°C. The results show that under idle operation, the spray collapsed towards the injector axis as the fuel temperature increased. At high fuel temperatures, the spray penetration increased so that the probability of fuel-wall impingement rises. As the fuel temperature increased from 20°C to 60°C, the AMD and SMD slumped by 43.6% and 33.2%, indicating the dramatic improvement in atomization quality. Concurrently, the droplet uniformity decreased sharply. As the temperature further increased to 90°C, the AMD and SMD only dropped slightly, but the droplet uniformity became better. Under WOT operation, no distinct evidence of spray deformation was found except for the case at 90°C. The AMD and SMD dropped steadily with the increase in fuel temperature, which is mainly attributed to the reduction in viscosity and surface tension. Besides, the droplet uniformity increased gradually along with the fuel temperature.

Gear rattle analysis of a torsional system with multi-staged clutch damper in a manual transmission under the wide open throttle condition

Vibro-impacts of a manual transmission in vehicle systems occur normally at the location of unloaded gear pairs, correlated with firing strokes from the engine. These vibro-impacts are possibly simulated by modeling the nonlinear dynamic characteristics and then, the problems can be resolved by efficiently designing multi-staged clutch dampers. For the sake of understanding rattle phenomena, a practical manual transmission with a front-engine and front-wheel drive configuration is investigated. First, the dynamic characteristics of the given system is examined on the basis of a modal analysis. Second, the nonlinear simulation model is developed under the wide open throttle condition by focusing on the third gear pair engaged and fifth gear pair unloaded case. Third, specific multi-staged clutch damper is examined using linear and nonlinear models, and rattle phenomena are investigated by employing a multi-staged clutch dampers with single- and dual-mass flywheels. Finally, estimation on the drag torque is conducted by assuming that the vehicle system is under the steady state condition. Thus, the rattle phenomena can be simulated under different driving conditions with the known input torque profiles.

Analysis of vibro-impacts in a torsional system under both wide open throttle and coast conditions with focus on the multi-staged clutch damper

Vibro-impacts of gear pairs in a torsion system inherently occur under the steady state torque input condition since clearance type nonlinearities are related to the torsional vibration induced by the firing stroke of an engine. In order to investigate the dynamic characteristics of gear rattle, front engine and front wheel drive configuration of the manual transmission is investigated under both wide open throttle and coast conditions. This configuration is examined using 6 degree-of-freedom system model, embedded by the relevant nonlinearities such as multi-staged clutch dampers, gear backlash and drag torques. This article focuses on the relationship of vibro-impacts with key parameters of clutch dampers, where the gear rattle phenomena are defined by “sing-sided”, “double-sided” and “no-impact” along with different clutch dampers. Thus, the mathematical model of the multi-staged clutch dampers is developed by including the asymmetric transition angles and pre-load effect. Based upon this nonlinear model, three real-life clutch dampers are employed and simulated results are compared with limited experimental measurements conducted on a vehicle. Also, the dynamic characteristics of gear motions under the coast condition are investigated. This coast condition is explained corresponding to different input torque conditions and its simulations show the main reasons of vibro-impacts induced by the clutch stopper well. Finally, modified clutch damper concepts for rattle-free transmission are proposed along with dynamic clutch design guidelines.

Experimental Study on the Effect of Concentrated Turbulence around the Spark Plug Zone in a Swirling Flow on a Hydrogen SI Engine Performance and Combustion Parameters

AbstractThis study investigates the effect of concentrated turbulence in the spark plug zone on engine performance and combustion parameters in a hydrogen engine. The swirling flow in the cylinder was directed to the spark plug zone by a turbulator-shaped piston head during the compression stroke. The engine was operated under lean mixture and wide-open throttle (WOT) conditions at different engine speeds. Depending on the engine speed, it was found that the concentrated turbulence around the spark plug zone enhances the engine performance between 4.3 and 7.8%. The combustion duration and the cyclic variation in the engine were also reduced with the concentrated turbulence in the spark plug zone. The reduction in combustion duration was higher in the first combustion period [0–10% mass fraction burned (mfb)] than that in the other two combustion periods (10–90% and 90–100 mfb). While the indicated mean effective pressure (imep) increased, the coefficient of variations of imep was markedly decreased thanks...

Lean burn performance of a hydrogen-blended gasoline engine at the wide open throttle condition

The performance of a hydrogen-blended gasoline engine at lean and the wide open throttle conditions was investigated. A hydrogen port-injection system was adopted to introduce the hydrogen into each cylinder. The engine was operated at 1400rpm and two hydrogen blending levels of 0% and 3%. The excess air ratio was raised from 1.00 to about 1.45 for a given hydrogen addition fraction. The test results demonstrated that the hydrogen blending contributed to the raised thermal efficiency and shortened flame development and propagation durations. An increased brake mean effective pressure was found after the hydrogen addition only at lean conditions. For both stoichiometric and lean conditions, the hydrogen blending was beneficial for reducing the engine cyclic variation. This provides a possibility to run a hydrogen-blended gasoline engine with the fully opened throttle position and control the engine torque only by adjusting the excess air ratio. Toxic emissions including HC, CO and particulate were reduced after the hydrogen blending.

Tailoring the key fuel properties using different alcohols (C2–C6) and their evaluation in gasoline engine

The use of ethanol as a fuel for internal combustion engines has been given much attention mostly because of its possible environmental and long-term economical advantages over fossil fuel. Higher carbon number alcohols, such as propanol, butanol, pentanol and hexanol also have the potential to use as alternatives as they have higher energy content, octane number and can displace more petroleum gasoline than that of ethanol. Therefore, this study focuses on improvement of different physicochemical properties using multiple alcohols at different ratios compared to that of the ethanol–gasoline blend (E10/E15). To optimize the properties of multiple alcohol–gasoline blends, properties of each fuel were measured. An optimization tool of Microsoft Excel “Solver” was used to find out the optimum blend. Three optimum blends with maximum heating value (MaxH), maximum research octane number (MaxR) and maximum petroleum displacement (MaxD) are selected for testing in a four cylinder gasoline engine. Tests were conducted under the wide open throttle condition with varying speeds and compared results with that of E15 (Ethanol 15% with gasoline 85%) as well as gasoline. Optimized blends have shown higher brake torque than gasoline. In the terms of BSFC (Brake specific fuel consumption), optimized blends performed better than that of E15. In-cylinder pressure started to rise earlier for all alcohol–gasoline blends than gasoline. The peak in-cylinder pressure and peak heat release rate obtained higher for alcohol gasoline blend than that of gasoline. On the other hand, the use of optimized blends reduces BSCO (Brake specific carbon monoxide) and BSHC (Brake specific hydrocarbon) emission with compared to the use of gasoline and E15. BSNOx (brake specific nitrogen oxides)emission of all alcohol–gasoline blends was higher than that of gasoline. However, MaxR, MaxD, MaxH reduces BSNOx significantly than that of E15. Thus, optimized multi alcohol–gasoline blends were found to be a better option in terms of fuel properties, engine performance, combustion and emission for an unmodified gasoline engine.

Effect of alcohol–gasoline blends optimization on fuel properties, performance and emissions of a SI engine

This study, as an observation, put its utmost effort to emphasize on the development of various physicochemical properties using multiple alcohols (C2 to C6) at different ratios compared to that of the conventional ethanolegasoline blend. To optimize the properties of multiple alcoholegasoline blends, properties of each fuel were measured first. An optimization tool of Microsoft Excel “Solver” was used for obtaining the optimum blend. Using optimizing tool, three optimum blend ratios were selected which possessed maximum heating value (MaxH), maximum research octane number (MaxR) and maximum petroleum displacement (MaxD). These blends were used for testing in a four cylinder gasoline engine at the wide open throttle condition with varying speeds and compared obtained outcomes with that of E15 (15% ethanol and 85% gasoline) as well as gasoline. Optimized blends have shown higher brake torque and brake thermal efficiency (BTE) but lower brake specific fuel consumption (BSFC) than E15. MaxR, MaxD and MaxH blends produced mean 4.4%, 1.8% and 0.4% increased BTE and mean 4.39%, 1.8% and 2.27% lower BSFC than that of E15. On the other hand, MaxR, MaxD, MaxH and E15 reduced 4.46%, 8.37%, 12.4% and 17.2%, mean CO emission and 4.5%, 11.81%, 8.19% and 16% mean HC emission respectively than that of gasoline. NOx emission of optimized blends was higher than gasoline. However, MaxR, MaxD,

An experimental investigation of hydrogen-enriched gasoline in a Wankel rotary engine

The Wankel rotary engine is a potential alternative to the reciprocating engine in hybrid applications because of its favorable energy to weight ratio. In this study, a Wankel rotary engine was modified to run on a hydrogen–gasoline blend. Hydrogen enrichment improved the performance of a lean-burn spark-ignition rotary engine operating at high speed and wide open throttle conditions with the original ignition timing, using 0%, %2, 4%, 5%, 7%, and 10% hydrogen energy fractions at the intake. The experimental results showed that adding hydrogen to gasoline in the engine improved the thermal efficiency and the power output. Hydrocarbon and carbon monoxide emissions were reduced while nitrogen oxide emissions increased with the increase of hydrogen fraction.

Realizing the part load control of a hydrogen-blended gasoline engine at the wide open throttle condition

This paper proposed a way for realizing the load control of a hydrogen-blended gasoline engine running at the wide open throttle (WOT) condition through lean combustion. The engine performance of the original gasoline engine and a 3% hydrogen-blended gasoline engine running at the WOT and lean conditions under various loads at a constant engine speed of 1400 rpm was compared. The experimental results showed that because of the reduced residual gas fraction and throttling loss, brake thermal efficiency of the 3% hydrogen-blended gasoline engine running at the WOT and lean conditions was obviously higher than that of the pure gasoline engine. The 3% hydrogen-blended gasoline engine running at the WOT and lean conditions produced much lower particulate and CO emissions than the original gasoline engine. Besides, NOx emissions at part load conditions were also reduced for the 3% hydrogen-blended gasoline engine running at the WOT and lean conditions.

A Power Generation Study of a Power Pack Based on Operating Parameters of the Linear Engine Fuelled with Propane

In this paper, we present our experimental research on a power pack based on operating conditions of the linear engine and the linear generator structure for generating electric power. The power pack used in the study consisted of a two-stroke free-piston linear engine, linear generators, and air compressors. Each parameter of input caloric value, equivalence ratio, spark timing delay, electrical resistance, and air gap length were settled for identifying the electrical power generation of the linear engine. The linear engine was fueled with propane, and in the course of all its operations, intake air was inputted under the wide open throttle condition. The air and fuel mass flow rate were varied by a mass flow controller and premixed by a pre-mixing device. The premixed gas was then directly supplied into each combustion cylinder. The experiments confirmed that power generation was induced differently for each respective operating condition. The maximum generating power was found with the value of 111.3W, where the operating conditions were as follows: 1.0 of equivalence ratio, 1.5ms of spark timing delay, 30Ω of electric resistance, and 1.0mm of air gap length.</abstract>

EGR Effect On Performance of a Spark Ignition Engine Fueled with Blend of Methanol-Gasoline

This paper examines the results of performance of a single cylinder spark- ignition engine fuelled with 20% methanol +80% gasoline (M20), compared to gasoline. The experiments were conducted at stoichiometric air–fuel ratio at wide open throttle and variable speed conditions, over the range of 1000 to 2600 rpm. The tests were conducted at higher useful compression ratio using optimum spark timings and adding recirculated exhaust gas with 20% to suction manifold.&#x0D; The test results show that the higher compression ratio for the tested gasoline was 7:1, 9.5:1 for M20 and 9:1 for M20 with added EGR. M20 at higher useful compression ratio (HUCR) and optimum spark timing (OST) characteristics are significantly different from gasoline. Within the tested speed range, M20 consistently produces higher brake thermal efficiency by about 6%. Also it resulted in approximately 3.06% lower brake specific fuel consumption compared with gasoline. Adding EGR to M20 caused reduction in HUCR and advancing the OST. This addition increased brake specific fuel consumption (BSFC), reduced brake thermal energy, volumetric efficiency and exhaust gas temperatures.

Naturally aspirated and boosted controlled auto-ignition combustion with positive valve overlap in a four-stroke gasoline engine

Extensive engine experiments were carried out on controlled auto-ignition combustion, also known as homogeneous charge compression ignition, in a four-stroke gasoline engine, by internally recycling burned gases through positive valve overlap, variable compression ratio, intake temperature control and boosting. The operational range of controlled auto-ignition combustion was determined for a range of compression ratios and intake air temperatures at wide-open throttle conditions. This was followed by further engine experiments with boosted intake and external exhaust gas recirculation in order to evaluate their effect on the operational range of controlled auto-ignition combustion and the engine’s performance and emissions. It has been found that the controlled auto-ignition operational region could be extended to the higher load region by boosting and running with leaner mixtures, whilst the use of external exhaust gas recirculation allowed the engine to operate controlled auto-ignition combustion optimized in the region between naturally aspirated and lean boosted controlled auto-ignition operational regions. The highest fuel conversion efficiency was obtained when the exhaust heat could be utilized to supply the intake air heating.

Power output characteristics of hydrogen-natural gas blend fuel engine at different compression ratios

Potential and knocking characteristics of a hydrogen-natural gas blend (HCNG) engine with a high compression ratio were examined from a commercial viewpoint since lean combustion with HCNG under a wide-open throttle (WOT) condition requires a high-charging-capacity turbocharger. Supercharging of intake air to extend the lean limit was investigated for a turbocharged, heavy-duty natural gas-fueled engine. Effects of compression ratio changes on fuel economy were assessed in terms of thermal efficiency and torque characteristics. Extension of the lean limit to an excess air ratio of 1.8 for an HCNG engine under WOT conditions is realizable using a supplementary supercharging system. Thermal efficiency improvement at high compression ratios is reduced under relatively rich mixture conditions because spark timing is retarded to avoid knocking. The excess air ratio corresponding to maximum thermal efficiency decreases to 1.6 for an HCNG engine due to the decrease in exhaust gas energy for intake-air charging.

The effects of modified ignition timing on cold start HC emissions and WOT performance of an LPG fuelled SI engine with thermal barrier layer coated piston

In this study, the effect of modified ignition timing of an LPG fuelled spark ignition engine on cold start Hydrocarbon emission (HC) at the wide open throttle (WOT) conditions performance and emission characteristics were investigated when using a thermal barrier layer (TBL) coated piston. The engine was tested at the variable ignition timing. At the first stage cold start HC emission was measured for the first 180 s. Secondly, the performance and HC emissions were measured at the WOT condition. Cold start HC emission in the TBL piston has been decreased considerable. In the case of using TBL piston and variable ignition timing, at the high engine speed the engine torque and brake power have been increased as 15% at the 2700 rpm. Specific fuel consumption (SFC) was decreased at the variable ignition timing expect for 1500 and 1800 rev min-1. Maximum reduction was observed by 8.5% at the 2700 rpm. Key words: Hydrocarbon emissions, cold start, thermal barrier layer, liquefied petroleum gas.

Experimental Test of a New Compressed Natural Gas Direct Injection Engine

This paper presents experimental test results of a new compressed natural gas direct injection (CNGDI) engine that has been developed by modifying a multicylinder gasoline port injection engine. The major modifications done are (1) a modification of the injection system to gas direct injection using new high-pressure gas injectors, (2) a change of the compression ratio from 10 to 14 through modification of piston and cylinder head, (3) and new long edge spark plugs. The CNG pressure at the common rail is kept constant at 20 bar. The engine has been operated at wide open throttle (WOT) condition to compare all the results with the original base engine. Hence, two engines are tested in this investigation. The test was conducted on a computer-controlled dynamometer to measure brake power; specific fuel consumption; volumetric efficiency; and exhaust emissions such as carbon monoxide (CO), oxides of nitrogen (NOx), and unburned hydrocarbon (HC). The objective of this investigation is to compare the test results between a CNGDI engine and a gasoline engine. It was found that the CNGDI engine produces a 4% higher brake power at 6000 rpm as compared to the original gasoline-fueled engine. The average brake specific fuel consumption (BSFC) of the CNGDI engine was slightly lower (about 0.28%) than the base engine. The CNGDI engine reduces 50% NOx emission as compared to base engine. However, the CNGDI engine produces higher HC and CO emissions as compared to the base engine by 34 and 48%, respectively. The results of this experiment will be used to further improve the CNGDI engine as well as to develop a new CNGDI car. The detailed results including fuel mapping are presented with discussions.

Effects of Ethanol Content on Gasohol PFI Engine Wide-Open-Throttle Operation

The NOx emission and knock characteristics of a PFI engine operating on ethanol/gasoline mixtures were assessed at 1500 and 2000 rpm with λ =1 under WideOpen-Throttle condition. There was no significant charge cooling due to fuel evaporation. The decrease in NOx emission and exhaust temperature could be explained by the change in adiabatic flame temperature of the mixture. The fuel knock resistance improved significantly with the gasohol so that ignition could be timed at a value much closer or at MBT timing. Changing from 0% to 100% ethanol in the fuel, this combustion phasing improvement led to a 20% increase in NIMEP and 8 percentage points in fuel conversion efficiency at 1500 rpm. At 2000 rpm, where knocking was less severe, the improvement was about half (10% increase in NIMEP and 4 percentage points in fuel conversion efficiency). Because there was no significant change in the end gas temperature in these experiments, the gasohol knock resistance was attributed solely to the ignition chemistry of the ethanol.

Effects of M15 blend on performance and exhaust emissions of spark ignition engine with thermal barrier layer coated piston

AbstractIn this study, the effects of 15% methanol + 85% gasoline blend (M15) on cold start HC emissions and performance of an spark ignition engine at idle and wide open throttle (WOT) conditions were investigated when using a thermal barrier layer (TBL) coated piston under various compression ratios (CRs). The performance tests were implemented at three CRs of 8·2, 7·2 and 6·2 for both standard (STD) and TBL piston. When M15 blend was used in the engine with TBL piston at idle, cold start HC emissions decreased considerably at the CR of 7·2. Maximum decreases of 49·45, 47·05 and 32·2% in HC emissions of the engine with TBL piston at WOT were found at the CRs of 8·2, 7·2 and 6·2 respectively. It was observed that the brake power increased at all CRs without knocking, compared to that of the STD engine. Maximum increases of 5·8, 7·56 and 2·55% in the brake power were reached at the CRs of 6·2, 7·2 and 8·2 respectively. Specific fuel consumption of TBL piston engine was found 3·4% lower than that of the ST...

Particle Image Velocimetry Measurements of In-Cylinder Flow in a Four-Stroke Utility Engine and Correlation With Combustion Measurements

Large-scale flows in internal combustion engines directly affect combustion duration and emission production. The effect of intake port geometry on combustion performance was studied in a four-stroke spark-ignition utility engine. Three intake port geometries were investigated at three port orientations. In-cylinder flows in orthogonal planes were measured using particle image velocimetry (PIV). The PIV data were processed to calculate the large-scale mean vorticity and mean high-pass filtered velocity. Combustion performance data were separately acquired at two load conditions at a fixed equivalence ratio, and compared with the PIV data. The cumulative distribution functions of the flow parameters did not show significant port-to-port differences in either measurement plane. The mean vorticity and high-pass filtered velocity did exhibit differences due to port orientation in the horizontal plane, but not in the vertical plane. The 0 deg ports (tangential orientation) consistently produced the highest values of large-scale mean vorticity and mean high-pass filtered velocity in the horizontal plane. The kinetic energy present at ignition was also calculated to characterize the flow. The ensemble-averaged values of the mean large-scale vorticity, high-pass filtered velocity, and kinetic energy were compared to the combustion duration. The vertical-plane vorticity and high-pass filtered velocity did not correlate with combustion performance. The horizontal-plane vorticity and high-pass filtered velocity were found to exhibit modest correlation at the fixed torque condition, and somewhat lower correlation at the wide open throttle condition. The correlation between kinetic energy and combustion duration was poor. The best correlation of flow field structure with engine performance was achieved for ports at the 0 deg port orientation. Ports at this orientation generated coherent, large-scale swirl.