Low-octane Gasoline Research Articles

The effects of limonene and eugenol additives in n-heptane and low-octane gasoline on the emission characteristics and fuel consumption of single-cylinder gasoline engine

This study investigated the effects of two additive polarities: polar (eugenol) and nonpolar (limonene) additives blended into n-heptane and low-octane gasoline. These compounds were chosen due to their unique molecular structure characteristics which influences the exhaust emissions. The physicochemical properties, fuel consumption, and exhaust gas emissions of a single-cylinder gasoline engine were measured. Four fuel blends were created by blending eugenol and limonene on a volumetric basis, n-heptane-eugenol (NHE), n-heptane-limonene (NHL), low-octane gasoline-eugenol (GE), and low-octane gasoline-limonene (GL). Tests were conducted on a single-cylinder gasoline engine. The exhaust gas emissions were analyzed using gas chromatography, and the role of each additive substance in the formation of carbon monoxide (CO), unburned hydrocarbon (HC), residual oxygen (O2), and carbon dioxide (CO2) emissions was validated using Hyperchem simulation and gas chromatography mass spectrometry. Owing to differences in the molecular structure and energy content of the two additives, the fuel consumption of NHE-fueled vehicles increased by 19.69% compared to NHL, whereas GE decreased by 32.15% compared to GL. Owing to the presence of oxygen atoms and low binding energy, blending eugenol with n-heptane and low-octane gasoline significantly reduced CO by 1.87% higher than limonene. However, eugenol’s aromatic structure can only reduce 14.45% of HC emission, while limonene, with its dynamically moving electrons and nonpolar properties can reduce up to 18.24%. It was discovered that the two additives could improve the quality of exhaust gas emissions.

Effects of fuel injection pressure and quantity on low octane gasoline sprays in a simulated high-pressure ambient environment of a gasoline compression ignition engine

Gasoline Compression Ignition technology using low-octane gasoline-like fuel can lead to very low NOx and Soot emissions and enhanced thermal efficiency than conventional diesel engines. The difference in test fuel properties is a significant reason for the difference in the fuel–air mixture formation in Gasoline Compression Ignition engines offering these advantages. In this study, microscopic and macroscopic spray characterisation of baseline diesel, 50 % v/v diesel blended with 50 % v/v gasoline (G50), and 20 % v/v diesel blended with 80 % v/v gasoline (G80) are conducted in a high-pressure ambient environment relevant to Gasoline Compression Ignition engines. The study was performed in a constant volume spray chamber in non-reacting conditions using Phase Doppler Interferometry and Diffused Backlit Illumination techniques. The test fuels were injected into a 30 bar ambient pressure environment at 400, 500, and 700-bar fuel injection pressures. The liquid spray penetration length of gasoline-diesel blends was slightly shorter than baseline diesel, but their spray cone angles and entrained air mass were significantly higher. The average axial droplet velocity was higher, and the Sauter Mean Diameter was lower for gasoline-diesel blends than baseline diesel 40 mm away from the injector nozzle exit, indicating superior mixture formation for the gasoline-diesel blends. The effect of droplet collision and injected fuel quantity on droplet size distribution was assessed in all test fuels. Droplet collisions increased the Sauter mean diameter of the spray at farther distances. Smaller fuel injection quantities decreased the Sauter mean diameter of the spray, increasing the probability of unburnt hydrocarbon emission producing ultra-lean regions in the engine combustion chamber.

Spark ignition engine performance analysis with low octane gasoline and Methyl tert-butyl ether additive for optimum operation

Spark ignition engine performance analysis with low octane gasoline and Methyl tert-butyl ether additive for optimum operation

On the influence of low octane gasoline and biodiesel on diesel engine operating characteristics

Biodiesel is a promising alternative fuel, but it has drawbacks. This research aims to diminish the NOx dilemma for diesel and biodiesel by utilizing straight-run naphtha as an additive. It has a low carbon footprint of production from light distilled crude oil without any requirement for the thermal cracking process. The diesel was blended with naphtha at percentages of 5%, 10%, and 15% that abbreviated by N5, N10, and N15, respectively. The biodiesel/diesel blend was mixed with the same naphtha concentrations forming the blends B30N5, B30N10, and B30N15, respectively. Experiments were applied on a single-cylinder engine at 2,000 rpm and different loads. The findings revealed that N15 declined the brake specific fuel consumption (bsfc) at most loads relative to neat diesel. Contrarily, biodiesel blends reflected a spiking trend of bsfc at tested loads. Notably, the NOx emissions declined with N15 blend at high loads relative to neat diesel. The blends B30N15 and B30N10 reduced NOx at high loads compared to the diesel/biodiesel blend. The straight-run naphtha was found to be a promising additive because the balanced composition of the iso-paraffins and n-paraffins. Hence, it dominated the ignition tendency and reduced NOx emissions due to its cooling effect.

High-efficiency combustion of gasoline compression ignition (GCI) mode with medium-pressure injection of low-octane gasoline under wide engine load conditions

Gasoline Compression Ignition (GCI) mode with medium injection pressure has the potential to achieve high engine efficiency while keeping costs low. In this study, the combustion and emission characteristics of GCI mode with medium-pressure injection of low-octane gasoline were studied and compared to conventional diesel combustion (CDC) under wide engine loads. The results showed that under low to medium loads, GCI mode had improved particulate emissions and indicated thermal efficiency (ITE) compared to CDC mode. However, at high loads, the PM emissions were much higher than CDC mode, and the ITE decreased for IMEP increasing from 10 to 12 bar due to limited injection pressure. To address this, a dual direct injection GCI mode with medium injection pressure was proposed to improve combustion under high loads. With this strategy, NOx emissions were significantly reduced, and ITE was simultaneously improved for IMEP of 10 and 12 bar. Using low octane gasoline and dual direct injection, the ITE of GCI mode can reach or exceed 50% for IMEP from 4 to 12 bar. Compared to gasoline with a research octane number (RON) of 83, gasoline with an RON of approximately 72 had higher ITE under most tested conditions and is recommended as the fuel for GCI mode.

Evaluation of Spark Ignition Engine Performance and Operation Stability with Low Octane Gasoline and Methyl Tert-Butyl Ether Additive

Evaluation of Spark Ignition Engine Performance and Operation Stability with Low Octane Gasoline and Methyl Tert-Butyl Ether Additive

Effects of different additives on physicochemical properties of gasoline and vehicle performance

Using fuel additives to improve fuel quality is considered to be a simple and cost-effective measure to energy saving and emission reduction. In this work, eleven additives including Iso-butanol, Ethyl tert-butyl ether, Iso-propyl ether, Aniline, Diethylamine, Dimethyl carbonate, Sec-butyl acetate, Iso-butyl acetate, Dimethyl malonate, P-methyl phenol, and P-tert-butyl phenol were chosen to study the effects of additives on physicochemical properties of China commercially 92# and 95# gasoline and vehicle performance using New European driving cycle. Results show that low octane gasoline is more significantly affected by additives. Alcohol, ether, amine, and ester additives mainly affect 50% evaporating temperature of gasoline, while phenolic additives mainly affect 90% evaporating temperature and increase Drivability Index. Ethyl tert-butyl ether improves research octane value greatly with little change in reid vapor pressure. All additives can improve the fuel economy and reduce CO emissions of 92# gasoline but have no significant effect on 95# gasoline. Most additives reduce THC emissions of 92# gasoline but increase THC emissions of 95# gasoline. All additives increase NOx emissions of 92 # gasoline, but Iso-butanol, Iso-butyl acetate, and P-methyl phenol reduce NOx emissions of 95 # gasoline. In addition, all additives improve the acceleration performance both 92# and 95# gasoline.

Gasoline compression ignition (GCI) combustion in a light-duty engine using double injection strategy

Controlling the oxides of nitrogen (NOx) and particulate matter (PM) emissions is one of the vital goals of compression ignition (CI) engines. Implementing stringent emissions regulations has motivated researchers to adopt various strategies for controlling emissions. Gasoline compression ignition (GCI) has emerged as a prime technology to control emissions and increase engine efficiency, while using low-octane gasoline as fuel in CI engines. Preheated air, hot exhaust gas recirculation (EGR), and negative valve overlap, are required to manage the combustion instabilities in the GCI engines. However these techniques have not been used in this study in order to reduce system complexity. Low octane test fuel was prepared (G80) by blending 80 % v/v gasoline and 20 % v/v diesel. This study involved experiments to evaluate the effects of main injection timing, split injection quantities (10–30 %), and engine load (brake mean effective pressure (BMEP): 3–5 bar) on a two-cylinder GCI engine’s performance, combustion, cyclic variability, emissions, and particulates. Conventional diesel combustion (CDC) mode experiments were performed using diesel. The results indicated a 5 % higher brake thermal efficiency (BTE) and comparable exhaust gas temperature (EGT) for the GCI mode compared to the baseline CDC mode. GCI combustion with low split ratio showed higher in-cylinder pressure than CDC mode. Baseline CDC mode showed < 3 % coefficient of variation of indicated mean effective pressure and peak pressure, whereas these parameters varied from 1 % to 9 % in the GCI mode. GCI mode engine exhibited ∼ 60 and 50 % lower NOx and PM emissions than baseline diesel mode engine. The double injection strategy improved GCI engine's performance and emission characteristics.

Comparative Analysis and Performance Characteristics of Bio-Additives Induced Fuel Blend

Global demand for efficient transportation and energy dissipation in industries that use engine-powered equipment is enormous and largely supplied by liquid fuels derived from petroleum that power internal combustion engines (ICEs). Since the demand for jet fuel and diesel is anticipated to surpass gasoline consumption in the near future, low-octane gasoline components will become more widely available. As a result, low-octane gasoline components are expected to become more readily available, as demand for jet fuel and diesel is expected to outpace gasoline consumption in the near future. Experimentally, the effects of organic fuel additives (OFAs) on the performance of internal combustion engines were investigated. The findings compare plain, commercially available, neat gasoline samples to pure ethanol and fuel samples injected with OFAs. The development of various fuel blends; the analysis and characterization of fuel samples, including blended fuel samples; and the experimental investigation and comparative analysis of the engine performance powered by the various samples and blends of gasoline on the TQ TD115 MK11 testbed for single-cylinder engines were carried out in the study. The study demonstrated that the nanoadditions were superior to pure ethanol and undiluted gasoline in terms of performance. and showed that pure ethanol has a high torque value at lower speeds, but at speeds greater than 3000 rpm, D-NA outperformed ethanol additives and neat gasoline in terms of torque. At lower speeds, pure ethanol also had a high brake power value, but as speeds increased, samples containing D-NA outperformed ethanol additive and neat gasoline in brake power. Pure ethanol in a concentration of more than 3 has a high brake thermal efficiency value at lower speeds, but as speeds increased, samples containing D-NA outperformed ethanol additive and neat gasoline in terms of brake thermal efficiency. Keywords: Fuel additives; ethanol; brake power; Internal combustion engine; fuel

Optimization of SI Engine Performance Operating with Low Octane Gasoline and Fuel Additives from Waste

Fuel additives from waste have been suggested to enhance low octane commercial gasoline in this study. Four samples were prepared in addition to pure commercial gasoline and denoted as GF0, GF4, GF8, GF12, and GF 16 which refer to fusel oil addition ratio of 0%, 4%, 8%, 12, and 16% respectively. Engine speed was controlled and increased manually from 1000 rpm to 3000 rpm at an increment of 500 rpm. Design of experiments is used to indicate the optimum additive dosage through response surface method optimization. Obtained results show that increasing engine speed significantly impacts the engine brake power, brake-specific fuel consumption, and brake thermal efficiency with a slight change for fusel oil ratio. Accordingly, it can be concluded that the maximum increase in output variables is statistically linked with the engine speed. The output response values at optimized conditions were 2.61812 kW brake power, 0.2431 kg/kW.hr brake-specific fuel consumption, and 36.5303% brake thermal efficiency. Based on the P-value, ANOVA data indicate that engine speed was a significant factor influencing output responses, while the fusel oil ratio was insignificant. However, fusel oil ratio of 8% has a significant effect on the brake thermal efficiency and BSFC.

FORENSIC INVESTIGATION OF OXYGENATES IN MOTOR TYPES OF GASOLINE

The main types of oxygenates, which are used in the manufacture of motor types of gasoline, are considered. Oxygenates (oxygen-containing compounds) is the general name for lower alcohols and ethers used as high-octane components of motor fuels. For the manufacture of motor types of gasoline, a low-octane base is used to which high-octane components are added. In many cases, lower alcohols (methanol, ethanol, etc.) and ethers (methyl tert-butyl ether, tert-amyl methyl ether, etc.) are used as high-octane components of motor types of gasoline. Straight-run gasoline and stable gasoline are often used as the low-octane gasoline base for mixed motor types of gasoline. Methanol (CH3OH) is the simplest monohydric alcohol. Methyl alcohol is now produced synthetically from carbon monoxide (CO) and hydrogen (H2). Ethanol (ethyl alcohol) is a representative of monohydric alcohols with the formula C2H5OH. The production of ethyl alcohol is possible in several ways: biochemical, hydrolysis, synthetic, or ethylene hydration. For the manufacture of motor types of gasoline, dehydrated ethyl alcohol (bioethanol, an alternative universal component of motor fuel (KMPU), etc.) is used. Bioethanol is produced according to DSTU 7166: 2010 “Bioethanol. Technical mind”. According to DSTU 7166: 2010, bioethanol is dehydrated ethyl alcohol made from biomass or from raw ethyl alcohol for use as biofuel. As a technological and denaturing additive, gasoline (petroleum products) is introduced into bioethanol in an amount of up to 1.5 % by volume. KMPU is produced in accordance with TU U 20.5-00372536-001: 2013 “Component of firing motor alternative universal (KMPU). Technical conditions”. An alternative universal motor fuel component is dehydrated ethyl alcohol with a complex of additives, which is used for the manufacture of mixed motor types of gasoline and alternative types of motor types of gasoline. Compositionally, KMPU is similar to bioethanol but differs from it in the presence of another high-octane component – methyl tert-butyl ether (MTBE). Methyl tert-butyl ether, formula CH3-O-C (CH3)3 is a product that can be obtained in large quantities by reacting isobutylene with methanol. The advantage of MTBE is its good solubility in gasoline, and, at the same time, it is not washed out of it with water. MTBE does not impair the physical and chemical stability of gasoline; it is characterized by stable anti-knock properties during storage and operation. The article discusses the results of the study of the listed oxygenates by gasliquid chromatography. This method makes it possible to establish the qualitative and quantitative composition of oxygenates and motor types of gasoline based on them. It is shown that from readily available petroleum components (stable gas gasoline) without the use of complex technological equipment by mixing with oxygenates, it is possible to obtain a gasoline mixture with a high detonation resistance, which is fake gasoline in composition. When mixing in certain proportions a low-octane gasoline base, for example, stable gas gasoline and oxygenates (lower alcohols, ethers), which have appropriate performance characteristics, it is possible to obtain commercial gasoline that will meet the requirements of regulatory documents (DSTU) for motor types of gasoline. The considered technology also allows, when mixing in the calculated proportions of commercial gasoline A-92 (A-95) with oxygenates and stable gasoline, to improve the operational characteristics (knock resistance) of the obtained gasoline mixture or to increase the volume of the resulting gasoline mixture without improving its operational characteristics. Key words: blended types of gasoline, alternative types of gasoline, oxygenates, lower alcohols, ethers, bioethanol, alternative motor fuel component universal.

Analysis of SI Engine Operation and Emission Characteristics with Low Octane Gasoline and Ether Additive

Analysis of SI Engine Operation and Emission Characteristics with Low Octane Gasoline and Ether Additive

Perspective towards a gasoline-property-first approach exhibiting octane hyperboosting based on isoolefinic hydrocarbons

Shortage in the production a high-octane gasoline is the key issues in the petroleum refineries. To overcome on this problem, isoolefinic hydrocarbons are suggested as prospective candidates as gasoline additives, due to their high antiknocking properties. The current research paper aims to propose the perspective towards a gasoline -property-first approach exhibiting octane hyperboosting based on isoolefinic hydrocarbons into low-octane gasoline components. Test methods on isoolefinic hydrocarbons samples, i.e., isooctene and isohexene into base motor fuel were investigated. The results reported that ultimate concentrations of isooctene and isohexene were at 50 wt%. Besides, Motor octane number (MON) blends from primary reference fuels (PRF-70) and isoolefinic hydrocarbons changed nonlinearly. The results reported that MON’s blends were higher than MON’s pure isohexene and isooctene. The recent discovery can be called as octane hyperboosting. Likewise, the current discovery can propose an unexplored aspect of autoignition kinetics research for gasoline mixtures. This may provide a new mechanism for remarkable increasing gasoline octane rating, which is necessary for increasing combustion performance in internal combustion engines. This phenomenon can be explained by the kinetics of formation primary radical by either monomolecular cleavage of CH/CC bond, or cleavage under the action of an oxygen biradical. Isooctene enters into the formation of a primary hydrocarbon radical at a rate that is more than 28 times higher than those of n-heptane and isooctane. Therefore, a decrease in the content of isooctene to 50% reduced the rate of primary reactions by almost 2 times.

Operating of Gasoline Engine Using Naphtha and Octane Boosters from Waste as Fuel Additives

Fuel quality is an important indicator for the suitability of alternative fuel for the utilization in internal combustion (IC) engines. In this paper, light naphtha and fusel oil have been introduced as fuel additives for local low octane gasoline to operate a spark ignition (SI) engine. Investigated fuel samples have been prepared based on volume and denoted as GN10 (90% local gasoline and 10% naphtha), GF10 (90% local gasoline and 10% fusel oil), and GN5F5 (90% local gasoline, 5% naphtha and 5% fusel oil) in addition to G100 (Pure local gasoline). Engine tests have been conducted to evaluate engine performance and exhaust emissions at increasing speed and constant wide throttle opening (WTO). The study results reveal varying engine performance obtained with GN10 and GF10 with increasing engine speed compared to local gasoline fuel (G). Moreover, GN5F5 shows higher brake power, lower brake specific fuel consumption, and higher brake thermal efficiency compared to other investigated fuel samples over the whole engine speed. The higher CO and CO2 emissions were obtained with GN10 and GF10, respectively, over the entire engine speed and the minimum CO emissions observed with GN5F5. Moreover, the higher NOx emission was observed with pure local gasoline while the lowest was observed with GF10. On the other hand, GN5F5 shows slightly higher NOx emissions than GF10, which is lower than GN10 and gasoline. Accordingly, GN5F5 shows better engine performance and exhaust emissions, which can enhance the local low gasoline fuel quality using the locally available fuel additives.

Influence of sweet orange peel oil additive on physicochemical properties of gasoline

The effect of a sweet orange peel oil additive on fuel blends of low-octane gasoline was investigated. The additive contains limonene, β-myrcene, eugenol, and triacetin, which have characteristics resembling gasoline but with advantages in terms of molecular structure that can increase RON and produce a homogeneous mixture. The additive changed the molecular behaviors influencing the physicochemical properties of the fuel blends. The experiments were conducted using fuel blends with additive fractions of 0%–75% (v/v). The fuel blends were mixed manually in 50-ml volumes in closed beaker glasses under STP conditions. The physicochemical properties were then measured to evaluate the chemical molecular structure compositions, viscosities, densities, heating values, and RONs of the blends, to determine the effect of the fuel additive on engines.The results show that the additive compounds were able to change the molecular behaviors of the fuel blends. The fuel blends produced 50 hydrocarbon compounds from 32 pure gasoline hydrocarbon compounds, which influenced the physical properties of the blends. The viscosities, beyond the lowest value at approximately 1.8 cSt, exhibited an increasing pattern compared to the viscosity of base gasoline fuel. The density and heating values tended to increase, even though there were fluctuating values due to intramolecular force movement and differences in molecular dipoles in the fuel blends. The RONs of the fuel blends, with additive fractions of 1%, 5%, 10%, 25%, 50%, and 75%, increased to 88.2, 91.5, 92.1, 95.7, 103.9, and 120.45, respectively. The increase in RON was also affected by the additive components among the fuel-blend molecules, which reacted to form highly stable hydrocarbon molecules, particularly aromatic and branched hydrocarbons, that inhibited combustion at low temperatures. Therefore, sweet orange peel oil as an additive can improve the physicochemical properties of gasoline, and thus can be mixed with any commercial fuel, especially those with a low octane number. It can be used for engines that require standard physical and high-octane properties.

Effects of split injection strategy on the combustion, emission and economic performance of the low-octane gasoline fueled MPCI engines

Application of diesel fueled partially premixed compression ignition (PPCI) engines are limited due to its excessive pressure rise rate at high load. Multiple premixed compression ignition (MPCI) engines fueled with low octane number gasoline (LON) has the potential to operate at both low and high load, while effects of split injection strategy on performance of such engines have not been discovered yet. In the present study, comparisons of LON and commercial diesel are first conducted in a heavy-duty single cylinder engine. Then, pilot injection timing and main injection timing are varied individually to reveal their effects on the combustion, emission, and economic performance of the MPCI engine. Comparing with diesel, MPCI engines with LON merits a low pollutants emission due to the long ignition delay and good volatility of LON. Split injection strategy can reduce the NOx and PM emissions simultaneously for MPCI engine with LON, and also reduce fuel consumption.

Effect of swirl ratio on charge convection, temperature stratification, and combustion in gasoline compression ignition engine

Various low-temperature combustion strategies (namely, homogeneous charge compression ignition, reactivity controlled compression ignition, and partially premixed charge compression ignition) have shown the potential to comply with upcoming and prevailing stringent emissions legislations. Low octane gasoline has emerged as an ideal fuel candidate for premixed charge combustion under diesel-like conditions in gasoline compression ignition (GCI) engines. GCI is an excellent technology to rectify future global energy demand imbalance, because it aims to replace diesel (which is in short supply) with low octane fractions/naphtha (which is in surplus supply) in compression ignition engines. However, this novel combustion concept requires modifications in the conventional design of diesel engines. The combustion chamber shape and in-cylinder flows play a crucial role in charge distribution and temperature stratification. Therefore, understanding the combined effect of combustion chamber geometry and in-cylinder flows is essential for future engine designs. GCI combustion engine simulations for varying swirl ratios (SRs) were performed in CONVERGE CFD software to understand the effect of in-cylinder air motion on the mixture stratification and combustion. A 1/7th sector geometry for a conventional re-entry piston bowl was modeled and then simulated. Two different mechanisms were used for model validation. The results indicated that the large-scale flow structures govern the fuel distribution in the combustion chamber. The charge convection because of increased swirl has a substantial effect on the combustion characteristics of the engine. A distinguished ignition kernel was observed for all test cases. An interfacial region with counter-rotating vortices formed a lean mixture zone, hindering flame propagation and combustion. A lower SR, shallow depth piston, and modifications to avoid flame quenching in the squish zone need to be further investigated to optimize the engine performance.

Relative Change in SI Engine’s Emission and Performance Parameters Using New Locally Made Octane Enhancer

In this study, a new gasoline Octane enhancer was made in Al-Doura refinery in Baghdad andwas used with the Iraqi pool gasoline. The main objective of this study was to find an Octanebooster to the low Octane Gasoline produced by Al-Doura refinery that does adversely affect itschemical, physical or combustion properties. This additive was then added to gasoline indifferent percentages (2.5% till 15% Vol) and the blend’s properties e.g. calorific value, density,Octane number (RON and MON), gum content, sulfur content were measured. These blendswere then tested against the performance of the original pool gasoline using previously calibratedand tested software. The relative change in the engine performance was then observed andcompared. It was found that the octane number of gasoline significantly improved after additionof the additive, its gum content decreased, its calorific value decreased while the sulfur contentwas slightly increased. No major change in the engine performance was noticed except for thedecrease in peak cylinder temperature and the sulfur dioxide and nitrogen oxides level at 2.5%then increased with additives.

An experimental and modeling study of autoignition characteristics of two real low-octane gasoline fuels in a heated rapid compression machine at elevated pressures

Gasoline compression ignition (GCI) has received much attention due to its high efficiency and low emissions. The low-octane gasoline can be applied to extend the GCI operating range. However, there is limited knowledge of the autoignition chemistry for the low-octane gasoline. In this study, the ignition delay times (IDTs) of two real distillate gasoline fuels with research octane numbers (RON) of 72 and 83, denoted as G72 and G83 respectively, were measured in a heated rapid compression machine (RCM) over wide ranges of pressures (10, 15 and 20 bar), temperatures (670–940 K), equivalence ratios (0.5, 1.0 and 2.0), and diluted conditions. Both G72 and G83 exhibit apparent two-stage ignition characteristics with negative temperature coefficient (NTC) behavior in the low-to-intermediate temperature region. Considering the effects of exhaust gas recirculation (EGR) technology on GCI combustion, ignition characteristics of low-octane gasolines under simulated-EGR conditions were also studied by varying the N2/O2 ratio while fixing the fuel mole fraction. It is found that the NTC region moves towards the higher temperature side as the oxygen concentration decreases. Moreover, two six-component surrogates were formulated for G72 (28.4% n-pentane, 3.5% n-heptane, 24.5% 2-methylhexane, 26.3% 2,2,4-trimethylpentane, 13.8% cyclopentane, and 3.3% toluene, by mol.), and G83 (16.5% n-pentane, 10.6% n-heptane, 5.6% 2-methylhexane, 37.4% 2,2,4-trimethylpentane, 10.2% cyclopentane and 19.7% toluene, by mol.). Kinetic modeling was then conducted using a published kinetic model coupled with proposed surrogates. Sensitivity analysis results further revealed that compared with isooctane, cycloalkane chemistry is more important in the overall autoignition behavior at low temperatures.

Tailored Air-Handling System Development for Gasoline Compression Ignition in a Heavy-Duty Diesel Engine

The simultaneous application of new low-NOx emissions standards and greenhouse gas (GHG) rules has placed great pressure on the commercial vehicle industry and has driven demand for innovative solutions. One potential solution, gasoline compression ignition (GCI), utilizes gasoline’s lower reactivity to promote partially premixed combustion and extract efficiency while reducing the PM-NOx trade-off curve. Gasoline’s volatility allows for the use of higher levels of exhaust gas recirculation (EGR), a key enabler of GCI combustion. In order to deliver higher levels of EGR while maintaining sufficient boost pressure, a tailored and efficient air-handling system is critical. This work presents the analysis-led development of a low-NOx GCI air-handling system including both turbocharger matching and EGR configuration for a prototype heavy-duty GCI engine based on a model year 2013 Cummins ISX diesel engine using low octane gasoline (RON80). In the analysis-driven development process, a 1D engine system-level analysis was closely coupled with closed-cycle 3D CFD GCI combustion development. Three different boost systems were investigated using a validated 1D engine model: 1) the production turbocharger; 2) an off-the-shelf single-stage waste-gate turbocharger; 3) a prototype single-stage variable geometry turbocharger. For each boost system, three EGR configurations were evaluated: 1) a high-pressure EGR route; 2) a low-pressure EGR route; 3) a dual-loop EGR route. The air-handling system performance was first investigated over five steady-state engine operating conditions extracted from the ramped modal cycle supplemental emissions test. Then, through cosimulation using a Simulink-based engine controls model, the best performing candidates under transient operation through the Heavy-Duty Federal Test Procedure certification cycle were identified. The production turbocharger, designed for 4–6 g/kWh engine-out NOx, suffered from low combined turbocharger efficiency under the low-NOx GCI thermal boundary conditions. The prototype 1-Stage variable geometry turbocharger, when used with a high-pressure EGR configuration, demonstrated higher combined efficiencies, while the waste-gate turbocharger showed the best results when used with a dual-loop EGR system. All low-pressure only EGR configurations were found to incur additional pumping penalties due to the need for a back pressure valve to drive sufficient EGR levels. In the transient test cycle analysis, the single-stage high-pressure EGR system was capable of delivering the target boost and EGR, while the off-the-shelf waste-gate turbocharger, with its higher mass inertia, showed slower turbine response and a resulting lag in boost response. Unsurprisingly, the dual-loop EGR system also suffered from delays in EGR delivery during engine acceleration. In summary, the prototype single-stage variable geometry turbocharger with a high-pressure EGR system produced the best performance over both the steady-state and transient engine cycles and was identified as the best candidate for the prototype low-NOx heavy-duty GCI engine.