Low Octane Number Research Articles

Optimized energy efficient reactive distillation for octane upgrading with economic and environmental considerations

Advancing fuel efficiency and production technologies can significantly reduce “Well to Wheels” and “Octane on Demand” emissions. This has been accomplished by integrating intensified technologies in fuel refineries. However, maintaining low energy consumption and high octane number while considering the impact of operating conditions under uncertainty on the process feasibility remains a challenge. Therefore, this article proposes a novel absorption heat pump reactive distillation (AHPRD). Aiming to maximize the economic potential of the AHPRD, an optimization framework that considers operating conditions under uncertainty (i.e. temperature (T), pressure (P), reflux ratio (RR), and feed stage (FS)) is developed. The optimization framework synchronizes Monte Carlo simulation and particle swarm optimization (PSO) to maximize the net present value (NPV). The framework used a hybrid Python-DWSim interface platform. The AHPRD was further investigated and compared against existing processes, namely, a conventional process refinery (CP) and reactive distillation (RD), to improve energy saving, increase financial return, and cut CO2 emissions. Attractively, the AHPRD outperforms existing processes, both economically and environmentally, doubling profit values and avoiding 52.2% − 77.4% of CO2 emissions. This study believes that the future direction will be to build an artificial intelligence model for process optimization and economic prediction.

Effects of Dimethyl Ether and Propane Blends on Knocking Behavior in a Boosted SI Engine

<div>Dimethyl ether (DME) is an alternative fuel that, blended with propane, could be an excellent alternative for exploring the use of fuels from renewable sources. DME–propane blends are feasible for their comparable physicochemical properties; these fuels may be pressured as liquids using moderate pressure at ambient temperature. Adding a proportion of DME with a low octane number to a less reactive fuel like propane can improve the combustion process. However, the increased reactivity of the mixture induced by the DME could lead to the early appearance of knocking, and this tendency may even be pronounced in boosted SI engines. Hence, this study experimentally analyzes the effect of E10 gasoline (baseline) and DME–propane blends, with varying proportions of DME in propane ranging from 0% to 30% by weight, in increments of 5% on knocking tendency, combustion characteristics, gaseous emissions, and particle number concentration, under different intake pressure conditions (0.8, 0.9, 1.0, and 1.1 bar) in an SI engine. The results show that as the proportion of DME in the propane blend rises, the knocking tendency becomes more pronounced. That behavior intensifies with increasing intake pressure, but with 20% DME in the propane blend, reaching the maximum brake torque (MBT) without knocking in the four boosted conditions is feasible. The presence of knock limited the advance of combustion phasing and decreased the gross indicated thermal efficiency (ITEg) with E10 gasoline and 25% and 30% DME in propane blends under 1.0 and 1.1 bar boosted conditions. In these knock-limited circumstances, the NOx emissions decreased due to the retarded phasing, and THC and PN emissions increased due to the lower combustion stability, considerably raising the concentration of accumulation mode particles in the particle size distribution (PSD) compared to the other fuel blends tested.</div>

Alternative Options for Ebullated Bed Vacuum Residue Hydrocracker Naphtha Utilization

The vacuum residue hydrocracker naphtha (VRHN) is a chemically unstable product that during storage changes its colour and forms sediments after two weeks. It cannot be directly exported from the refinery without improving its chemical stability. In this research, the hydrotreatment of H-Oil naphtha with straight run naphtha in a commercial hydrotreater, its co-processing with fluid catalytic cracking (FCC) gasoline in a commercial Prime-G+ post-treater, and its co-processing with vacuum gas oil (VGO) in a commercial FCC unit were discussed. The hydrotreatment improves the chemical stability of H-Oil naphtha and reduces its sulphur content to 3 ppm. The Prime-G+ co-hydrotreating increases the H-Oil naphtha blending research octane number (RON) by 6 points and motor octane number (MON) by 9 points. The FCC co-cracking with VGO enhances the blending RON by 11.5 points and blending MON by 17.6 points. H-Oil naphtha conversion to gaseous products (C1–C4 hydrocarbons) in the commercial FCC unit was found to be 50%. The use of ZSM 5 containing catalyst additive during processing H-Oil naphtha showed to lead to FCC gasoline blending octane enhancement by 2 points. This enabled an increment of low octane number naphtha in the commodity premium near zero sulphur automotive gasoline by 2.4 vol.% and substantial improvement of refinery margin. The processing of H-Oil naphtha in the FCC unit leads also to energy saving as a result of an equivalent lift steam substitution in the FCC riser.

Experimental study on the effects of injection pressure on the combustion in a SI aviation piston engine fueled with kerosene

Kerosene becomes an alternative to gasoline in aviation piston engines for its safety and easy replenishment on some special occasions. However, the low octane number of kerosene tends to cause the knock of SI engine, as a result, most of the current SI kerosene engines run in an operation mode of two-stroke, which has the disadvantage of a low compression ratio and high fuel consumption. This study conducted a series of experiments on a two-stroke SI kerosene engine equipped with an air-assisted direct injection system to improve engine performance and fuel economy by increasing injection pressure and combining it with control strategy optimization. First, the effects of injection pressure on the combustion of kerosene engines were studied, including cylinder pressure, combustion rate, and the stability of combustion. The results show that increasing the injection pressure shortens the ignition delay, accelerates the combustion, and substantially improves the combustion stability. Then, the effects of increasing the injection pressure on the control strategies of injection advance angle, ignition advance angle, and fuel injection duration were investigated. Ultimately, based on the investigation of the effects of injection pressure on the control strategies, two optimizations of control strategies were obtained to reduce fuel consumption and increase power, respectively, with the former reducing fuel consumption by 14.9% and the latter increasing power by 6%.

Fischer-Tropsch wax catalytic cracking for the production of low olefin and high octane number gasoline: Process optimization and heat effect calculation

To produce low olefin gasoline with high octane number by Fischer-Tropsch (F-T) wax fluid catalytic cracking (FCC) process, operating conditions optimization were carried out in the pilot-scale riser and turbulent fluidized bed (TFB) FCC unit. The experimental results in the riser indicated that under the condition of low reaction temperature and regenerated catalyst temperature, large catalyst-to-oil weight ratio (C/O) and long reaction time, the gasoline olefin content could be reduced to 20.28 wt%, but there is large octane number loss owing to a great loss in high octane number olefin. Therefore, a novel FCC process using the TFB reactor was proposed to strengthen the aromatization reaction. The reaction performance of TFB reactor were investigated. The result demonstrated that the TFB reactor has more significant effect in reducing olefins and improving aromatics. At the expense of certain gasoline yield, the gasoline olefin content reduced to 23.70 wt%, aromatics content could increase to 26.79 wt% and the RON was up to 91.0. The comparison of reactor structure and fluidization demonstrated that the TFB reactor has higher catalyst bed density. The reaction heat and coke combustion heat was calculated indicating the feasibility of its industrial application of the TFB process.

Production of High-Octane Number Gasoline from Basra Low Octane-Number Gas Condensate and Ethanol over Modified Zn/ZSM5 Zeolite Catalyst

Catalytic transformation of a low-octane number stable gas condensate to high-octane number gasoline (RON: research octane number) is an economically and strategically vital process. In this research, modifying ZSM5 zeolite (80 Si/Al ratio) by impregnation with 2% Zn (Zn/ZSM5) was carried out to increase the selectivity for isomerization and aromatization thereby enhance the octane number. The process was conducted by using stable gas condensate 85 vol% with 15 vol% ethanol in a fixed bed reactor. Zn/ZSM5 and ZSM5 were examined in a pilot scale under different conditions temperature 360-420 °C LHSV1.2-2 h−1, pressure 5 bar. Catalysts were characterized before and after Zn loading using Fourier Transform Infra Red (FT-IR), Brunauer-Emmett-Teller (BET), X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Field Emission Scanning Electron Microscope (FESEM), Transmission Electron Microscope (TEM), and N2-adsorption. The SEM, FESEM, and TEM have shown that no change in morphology and metal distribution. The XRD and FTIR characterizations revealed the modified catalysts retained their crystallinity after metal impregnation while N2-adsorption isotherm demonstrates no significant change in porosity. The results of Zn/ZSM5 display an optimum result at 420 °C, 1.2 h−1, 5 bar with enhancement of RON from 60.5 to 89 whereas ZSM5 shows RON enhancement from 60.5 to 82. Post Zn loading, PONA test has shown an increase for iso-paraffin from 45.4 to 47.4%, and aromatics from 10.8 to 14. The findings translate the effectiveness of using Zn on ZSM5 for gas condensate – gasoline transformation. Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Effects of pre-mixed gas composition on combustion characteristics of micro pilot dual fuel (MPDF) in a heavy-duty dual fuel engine

The effects of premixed gas compositions on the combustion characteristics in micro pilot duel fuel (MPDF) conditions were investigated. Propane, hydrogen, and carbon dioxide gases were added to methane gas, and engine experiments were conducted under various premixed gas compositions. A single-cylinder heavy-duty engine with a combustion chamber volume of 1100 mm3 and compression ratio of 17.0 was used. A 55 kW DC dynamometer was used to operate the single-cylinder dual-fuel engine at a constant engine speed. At high propane mixture ratios, knocking combustion occurred, accompanied by intense engine vibrations, owing to the low octane number of propane. Knocking combustion led to an increase in the combustion variation and ringing intensity (which represents the knocking combustion intensity). In contrast, at high ratios of hydrogen, which has a high octane number, knocking combustion was suppressed, and the speed of combustion was lower than that in the case of high propane mixture ratios. The optimum conditions corresponded to a ringing intensity of 3–5 MW/m2. The addition of even a small amount of propane gas enhanced the engine performances in misfiring conditions. In contrast, a considerable amount of hydrogen gas was required to prevent abnormal combustion because of the low density of hydrogen gas. The presence of carbon dioxide effectively stabilized MPDF combustion by suppressing knocking combustion.

ROLE OF CATALYTIC REFORMING PROCESS FOR GASOLINE PRODUCTION IN ASEAN REFINERIES

The crude oils processed in refineries range from sweet crudes, such as Southeast Asian light Crudes, to sour crude, suck as Middle East. Far East, and Persian Gulf. For the period 1992-2005, the average annual demand growth rate for light products (gasoline, kerosene, diesel oil) is higher than residual fuel oil. These data clearly show that the need will continue for converting additional bottom into light products, by both thermal or catalytic conversions, The passage of the Clean Air Act Amendement of 1990 in the USA has forced American refineries to install new facilities to comply with stricter specifications for fuels such as gasoline and diesel oil such as Asia-Pacific, California Air Resources Board (CARB) and European Commission (EC), Various terms in the models address qualities of the gasoline blended such as benzene, total aromatics and olefm contents, RVP, the T90 of distillation range, sulphur content, and oxygenates content45, Motor gasoline is essentially a complex mixture of hydrocarbons distilling about 40°C and 220°C and consisting of compounds generally in the range C, to C2. Gasoline components can be produced by both the distillation of crude oil and the conversion of the crude oil fraction. Catalytic reforming process using bifunctional catalyst converts low octane number heavy naphthas into reformate with a high octane number. Bi-functional catalyst containing metal site (Pt, Pt/Ge) and acid site (A1,O,CI) are generally used. The balance is most important in a bifunctional reforming catalyst, and in fact it has to be different for different duties"l The end point of the naphtha feedstock is usually limited to about 185°C, partially because of increased coke deposition on the catalyst. The reforming cata- lyst exhibits a sensitivity to the conventional impurities of naphtha feed, such as: water (moisture), organic compounds of chlor, nitrogen and sulphur, and organometallic compounds (lead, copper, iron). Sintering of the metal phase becomes effective only beyond 500°C as measured by lowering of the dispersion of platinum atom condition, at the same time coke formation on the catalyst incrases tool71, The life of the catalyst will depend both on its stability and regenerability, expressed either in months or year, or in tonnage treated for unit weight of catalyst. This paper presents briefly composition of gasoline pool, specification of commercial gasoline in Indonesia as well as ASEAN refmeries, the catalyst improvements, catalyst deactivation and catalyst re- generation of the reforming process.

Experimental study of aviation kerosene engine with PJI system

The spark-ignition (SI) piston engine has become the main power source for unmanned aerial vehicles owing to its small size and large power/weight ratio. While gasoline is the commonly used fuel in SI engines, it affords poor safety and stability. Aviation kerosene is highly suitable as an alternative to gasoline; however, its high kinematic viscosity and low saturated vapour pressure afford poor evaporation and atomisation in SI engine. Moreover, aviation kerosene has a low octane number, and easy to cause knock, particularly in four-stroke engines. Those issue limits the wide use of kerosene in SI engines. In this study, the pre-chamber jet ignition (PJI) technology is used to suppress the knock of kerosene engine. The combustion characteristics of gasoline-SI, kerosene-SI and kerosene-PJI were compared and analysed. The variation law of indicated mean effective pressure (IMEP) at different speeds is obtained. It is found that PJI system can accelerate the flame propagation speed and shorten the combustion duration, and IMEP can be increased by 10%–27%. The experimental results show that PJI can optimise kerosene combustion to a certain extent and broaden its knock limit in SI engine. It is one of the effective ways to suppress knock in kerosene engine.

Improving of Pyrolysis Oil from Macroalgae Cladophora glomerata with HDPE Pyrolysis Oil

The slow pyrolysis of macroalgae at moderate temperatures in the reactor used resulted in an oil with a slightly better calorific value than that of the literature, but the other properties were not convincing. Therefore, co-pyrolysis with HDPE offers a way out in this study. However, this did not improve the property profile as a fuel, as the co-pyrolysate was incombustible due to its high water content. Only a mixture of the pyrolysis oil from algae and of the HDPE wax from the initial pyrolysis of HDPE resulted in a diesel-like product: the density was from 807 kg m−3, the viscosity 3.39 mm2 s−1, the calorific value was 46 MJ kg−1, and the oxidation stability was 68 min. The isoparaffin index indicates only a low branching of the paraffins, and therefore a low research octane number of 80. The blend did not need any further stabilizing additives.

Influence of CeO2 nanoparticles on methyl tertiary butyl ether gasoline blend in spark ignition engine

The search for suitable alternative for fossil fuel has been a challenge to the research community for the past two decades. So many alternatives have been identified and tested. However, a complete replacement cannot be provided without any penalties of cost, excess emission, poor operation, etc. The alcohols gave a new opportunity and a solution for that problem but had some setbacks of increased density and lower octane number. The present work focuses on striking a balance between advantages and disadvantages by using oxygenated additive with gasoline fuel. The additive CeO2 along with methyl tertiary butyl ether (MTBE) offers many advantages. The seven samples, namely M10, M15, M20, M25, M20 + 50 mg/l, M20+100 mg/l, M20+150 mg/l have been prepared and tested on spark ignition engine. Here, 10, 15, 20, and 25 denote the MTBE volume in blends and 50 mg/l, 100 mg/l, and 150 mg/l indicate the CeO2 in blends. The results have shown that only MTBE has caused an increase of 4% in brake thermal efficiency with M15 and then brake thermal efficiency has improved by 3% with M15 + 100 mg/l compared with pure gasoline. Fuel consumption has also been reduced upto 9% with M20 and 11% with M15+150 mg/l compared with pure gasoline. The maximum HC and CO reductions have also been observed from M20 and M20 + 150 mg/l. It was up to 19% and 22%, 23%, and 25% of HC and CO with M20, M20 + 150 mg/l. However, there has been an increase in CO2 emission level because of excessive unburned HC reduction. The MTBE with CeO2 has proved to be suited to all running conditions. The blends having more amounts of additive produce good combustion characteristics yet it should be restricted within 20 vol.% of MTBE and 150 mg/l of CeO2.

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.

Fischer-Tropsch wax catalytic cracking for the production of low olefin and high octane number gasoline: Experiment and molecular level kinetic modeling study

A molecular level kinetic model of Fischer–Tropsch wax catalytic cracking based on the structural unit and bond-electron matrix framework was developed. A molecular compositional model was built according to the detail molecular characterization data, containing 225 representative molecules. The reaction law was studied and then transformed to 17 reaction rules based on experimental data under different reaction conditions. All molecules traversed reaction rules, and a reaction network, including 700 molecules and 2029 reactions, was formed. The model parameters were reduced based on linear free energy relationship and tuned by experimental data. The predicted values of the model were in good agreement with the experimental data, with a maximum absolute error of 2.89 wt% and a minimum absolute error of 0.02 wt%. The model predicted that gasoline olefin content will achieve less than 25 wt% and RON > 90 under the reaction conditions of 510 °C, CTO 12 g/g and WHSV 6 h−1. The modelling also demonstrated that the feedstock was consumed rapidly, and multiple reactions could occur immediately. Thus, secondary reactions play an important role in the production of low olefin and high octane number gasoline.

Effects of n-heptane/toluene/ethanol ternary fuel blends on combustion, operating range and emissions in premixed low temperature combustion

Low temperature combustion engines are a new combustion model that the reduction of nitrogen oxide emissions and the increasing of the thermal efficiency can be observed simultaneously. In addition, the problem of misfire at low engine loads and knocking at high engine loads occurs. The fuels have low octane number can be used to eliminate the misfire problem at low engine loads, and the fuels have high octane number can be used to eliminate knocking problem at high engine loads. In this study, the operating ranges of low and high reactivity fuel mixtures with different chemical properties were experimentally investigated in a low temperature combustion engine. While high reactivity n-heptane, T10 and E10 fuels were used, it was seen to be suitable for HCCI strategy in wider and leaner mixing conditions, while low reactivity E20 and E30 showed good performance at high engine loads close to the knocking zone. The highest brake thermal efficiency was obtained as 44.5% with E30 fuel under extremely lean mixture conditions (ʎ = 2.95). While E20 fuel shows a good performance like E30, the fact that most of the combustion takes place before TDC in the use of high reactivity fuel caused low efficiency due to knock and heat losses. It can be stated that ethanol has low reactivity needs high inlet air temperature, high compression ratio or combustion improving additives such as n-heptane and toluene to be used in HCCl applications. The results obtained support the idea of fuel flex vehicles for the current engine.

Boosting the Octane Number of Gasoline by Natural Gas Concentrated in Methane

Gasoline obtained from the fractionation of indigenous natural gas condensate has low octane number (78) and is therefore of limited uses. Lead-based octane boosting and catalytic reforming are not the viable methods for many fractionation plants. This study was therefore aimed to develop an inexpensive conceptual alternative method for boosting the octane number of gasoline. Natural gas concentrated in methane having high octane number (more than 100) was absorbed in the gasoline to boost the octane number partially (86). Selective additives i.e. ethanol, tert-butyl alcohol, methylcyclopentane, toluene, iso-octane and xylene were blended first with the gasoline to aid the absorption of natural gas molecules. The loss of absorbed gas molecules from gasoline with the increase in temperature was also observed. It is therefore required to try for avoiding any increase in temperature in the finished gasoline. The developed conceptual method is promising. The findings of this simulation study would be useful for more studies towards the development of an affordable alternative method for fractionation plants for boosting the octane number of gasoline derived from natural gas condensate.

Simultaneous production of ketohydroperoxides from low temperature oxidation of a gasoline primary reference fuel mixture

Ketohydroperoxides (KHPs) are oxygenated hydrocarbons that include carbonyl and peroxide functional groups. The decomposition pathways of KHPs are chain branching pathways in low temperature chemistry of alkanes and oxygenated biofuels, which makes KHPs critical intermediates in ignition processes in advanced combustion engines. In this work, KHP formation was investigated in the low temperature oxidation of a primary reference fuel (PRF 70), a binary mixture of 30 vol% n-heptane and 70 vol% iso-octane to represent a low octane number gasoline surrogate. Species were detected and measured in a jet-stirred reactor (JSR), coupled with time-of-flight molecular beam mass spectrometer using synchrotron vacuum-ultraviolet radiation as photon ionization source (SVUV-PI-TOF-MBMS) which provides in-situ measurement of unstable KHPs. Simultaneous KHPs production from higher reactivity n-heptane and lower reactivity iso-octane at similar temperatures was observed. Kinetic modeling was used to study the reactivity across a wide temperature range and to examine KHP formation chemistry. Specifically, signals vs. temperature profiles in experiments and mole fraction vs. temperature profiles in simulations, were compared to indicate the most possible saturated KHP isomers. Possible formation pathways for olefinic KHPs and di-olefinic KHPs are discussed. This work reports simultaneous formation of KHPs from two fuel molecules in a gasoline surrogate mixture, discusses important reaction pathways in low temperature oxidation, and explains simultaneous KHP production in n-heptane/iso-octane mixtures, i.e., low temperature oxidation of less reactive iso-octane is initiated by OH radicals produced from high reactivity n-heptane oxidation.

Emission reduction in diesel engine with acetylene gas and biodiesel using inlet manifold injection

It is well known that acetylene has a wide flammability and is readily available and low-cost non-crude oil derivative fuel. According to the property of low motor octane number, the acetylene cannot be used alone in the internal combustion engine. Research has shown that the introduction of biodiesel results in a substantial reduction in the use of conventional fossil fuels and also in the amount of emissions. This study focuses on performance improvement and emission reduction of conventional diesel engine using acetylene gas as a low-reactivity fuel (LRF) and B20 mahua biodiesel as a high-reactivity fuel (HRF) in the reactivity controlled compression ignition (RCCI) mode. The computational fluid dynamics (CFD) principle is used to evaluate the optimal angle of the LRF injector to achieve better fluid flow mixing pattern in the inlet manifold. From the CFD simulation, an optimal LRF injection angle of 45° is defined in the intake manifold. The modified intake manifold engine is tested for performance, emission and combustion characteristics at different flow rates of acetylene through the injector. It is observed that the brake thermal efficiency (BTE) is increased by about 3.7% at a flow rate of 4 liters per minute (LPM) of acetylene injection in RCCI combustion mode compared to conventional biodiesel operation and significant decreases in polluting components such as smoke opacity, oxides of nitrogen (NOx), hydrocarbon (HC) and carbon monoxide (CO) are reduced by about 10%, 7.6%, 13.4% and 28.7%.

The effect of cooled EGR on combustion and load extension in a kerosene spark-ignition engine

It’s currently a trend to use aviation kerosene as the fuel for aviation spark-ignition reciprocating engines because of its good safety compared with gasoline during the transportation, storage and use. However, when converting the gasoline engines to kerosene, power density is constrained by knock combustion for its lower octane number, especially for four-stroke engines. In this study, cooled exhaust gas recirculation (EGR) was adopted to extend the output of a kerosene engine at knock limits based on a four-cylinder, four-stroke, horizontally opposed engine. First, the effects of cooled EGR on combustion characteristics are studied, including the in-cylinder pressure, heat release rate, knock intensity etc. Then, load extension via cooled EGR was experimental analyzed. The results show that when the EGR rate increased from 0% to 10%, the indicated mean effective pressure (IMEP) at knock limits improved by 7%. At the same time, because of higher specific heat ratio and reduced heat transfer loss, specific fuel consumption decreased by 8.1%, and the indicated thermal efficiency increased from 23.5% to 25.6%.

New recipes for producing a high-octane gasoline based on naphtha from natural gas condensate

Oxygenates should be added to gasoline fractions because they are environmentally friendly and have a high-octane rating. This research investigates new recipes for producing high-octane gasoline based on gas raw materials by using isooctene. Blend stocks from naphtha from natural gas condensate, isooctene, isopentane, (methyl tert-butyl ether) MTBE, isopentane, ethylbenzene, toluene, and isopropylbenzene with different percentages are blended to select the optimal samples in order to produce gasoline grades A92 and A95 in accordance with Russian and European standard regulations (GOST 32513 and EN228:2012). Physicochemical characteristics and operational properties of various components of the fuel are studied. Results showed that the quality of the produced gasoline is highly based on measuring oxidation stability via an induction period, where the value of it is more than 462 min. This indicates that optimal samples do not form gum during storage. Moreover, power at full load, minimum specific fuel consumption, as well as exhaust emissions, including carbon monoxide (CO) content, nitrogen oxides (NOX) content, and hydrocarbon (CH) content are given good prospects for produced gasoline. Finally, the quality and quantity of naphtha produced from natural gas condensate which has low octane number were maximized by blending with components of gasoline for producing high-octane gasoline. Moreover, the content of aromatic, olefin and benzene for an environmental gasoline in the general case exactly meets the conditions of the Russian and European standard rules according to GOST 32513-2013 and EN228:2012. Furthermore, an environmental gasoline gives good prospects to refining companies in light of decreasing the overhead, enhancing the grade of product, and great effect on the environment.