Oil Methyl Ester Blends Research Articles

Effect of a dimethyl ether–soybean methyl ester blend as an alternative fuel on the combustion and the distributions of nitrogen oxide emissions and soot emissions in a passenger car diesel engine

This paper investigates the effect of a dimethyl ether–soybean oil methyl ester blend as an alternative fuel on the combustion and the spatial distributions of nitrogen oxide emissions and soot emissions in a diesel engine using experimental and numerical approaches. The results obtained from the combustion and the emission characteristics (such as the heat release, the nitrogen oxide emissions, the soot emissions, the carbon monoxide emissions and the hydrocarbon emissions) of a dimethyl ether–soybean oil methyl ester blend are compared with the results from a conventional diesel fuel. The test fuels used in this investigation were dimethyl ether–soybean oil methyl ester blend, dimethyl ether and a conventional diesel fuel. The dimethyl ether–soybean oil methyl ester blend is a mixture of 80 wt % dimethyl ether and 20 wt % biodiesel fuel. A numerical calculation was conducted to analyse the combustion characteristics, the spray behaviours, the mixture formation, the emissions characteristics and the spatial distributios of nitrogen oxides and soot for the dimethyl ether–soybean oil methyl ester blend in a cylinder by using the AVL FIRE program. The numerical results showed that the combustion characteristics of the dimethyl ether–soybean oil methyl ester blend and diesel fuel were in good agreement with the experimental results, such as the combustion pressure and the rate of heat release. It was found that the effect of the dimethyl ether–soybean oil methyl ester blend on the combustion characteristics in an engine resulted in a shorter ignition delay and advanced ignition compared with those using conventional diesel fuel. In addition, the combustion duration of the dimethyl ether–soybean oil methyl ester blend was shorter than that of diesel fuel. The combustion effect of the dimethyl ether–soybean oil methyl ester blend on the concentration of the exhaust emissions indicated that the carbon monoxide emissions and the hydrocarbon emissions were lower than those from diesel fuel. On the other hand, the nitrogen oxide emissions of the dimethyl ether–soybean oil methyl ester blend slightly increased in comparison with those from diesel fuel. The soot emission concentration was nearly zero for the entire test range.

ARTIFICIAL NEURAL NETWORK OPTIMIZATION MODELING ON ENGINE PERFORMANCE OF DIESEL ENGINE USING BIODIESEL FUEL

This paper presents a study of engine performance using a mixture of palm oil methyl ester blends with diesel oil as biodiesel in a diesel engine, and optimizes the engine performance using artificial neural network (ANN) modeling. To acquire data for training and testing of the proposed ANN, a four-cylinder, four-stroke diesel engine was fuelled with different palm oil methyl ester blends as biodiesel, operated at different engine loads. The properties of biodiesel produced from waste vegetable oil were measured based on ASTM standards. The experimental results revealed that blends of palm oil methyl ester with diesel fuel provided better engine performance. An ANN model was developed based on the Levenberg-Marquardt algorithm for the engine. Logistic activation was used for mapping between the input and output parameters. It was observed that the ANN model could predict the engine performance quite well with correlation coefficients (R) of 0.996684, 0.999, 0.98964 and 0.998923 for the incylinder pressure, heat release, thermal efficiency, and volume, respectively. The predicted MSE (mean square error) error was between the desired outputs, as the measured and simulated values were obtained as 0.0001 by the model. Long-term effects on engine performance when running on biodiesel fuel can be further studied and improved.

Combustion analysis of microalgae methyl ester in a common rail direct injection diesel engine

In this study, the biodiesel properties and effects of blends of oil methyl ester petroleum diesel on a CI direct injection diesel engine is investigated. Blends were obtained from the marine dinoflagellate Crypthecodinium cohnii and waste cooking oil. The experiment was conducted using a four-cylinder, turbo-charged common rail direct injection diesel engine at four loads (25%, 50%, 75% and 100%). Three blends (10%, 20% and 50%) of microalgae oil methyl ester and a 20% blend of waste cooking oil methyl ester were compared to petroleum diesel. To establish suitability of the fuels for a CI engine, the effects of the three microalgae fuel blends at different engine loads were assessed by measuring engine performance, i.e. mean effective pressure (IMEP), brake mean effective pressure (BMEP), in cylinder pressure, maximum pressure rise rate, brake-specific fuel consumption (BSFC), brake thermal efficiency (BTE), heat release rate and gaseous emissions (NO, NOx, and unburned hydrocarbons (UHC)). Results were then compared to engine performance characteristics for operation with a 20% waste cooking oil/petroleum diesel blend and petroleum diesel. In addition, physical and chemical properties of the fuels were measured. Use of microalgae methyl ester reduced the instantaneous cylinder pressure and engine output torque, when compared to that of petroleum diesel, by a maximum of 4.5% at 50% blend at full throttle. The lower calorific value of the microalgae oil methyl ester blends increased the BSFC, which ultimately reduced the BTE by up to 4% at higher loads. Minor reductions of IMEP and BMEP were recorded for both the microalgae and the waste cooking oil methyl ester blends at low loads, with a maximum of 7% reduction at 75% load compared to petroleum diesel. Furthermore, compared to petroleum diesel, gaseous emissions of NO and NOx, increased for operations with biodiesel blends. At full load, NO and NOx emissions increased by 22% when 50% microalgae blends were used. Petroleum diesel and a 20% blend of waste cooking oil methyl ester had emissions of UHC that were similar, but those of microalgae oil methyl ester/petroleum diesel blends were reduced by at least 50% for all blends and engine conditions. The tested microalgae methyl esters contain some long-chain, polyunsaturated fatty acid methyl esters (FAMEs) (C22:5 and C22:6) not commonly found in terrestrial-crop-derived biodiesels yet all fuel properties were satisfied or were very close to the ASTM 6751-12 and EN14214 standards. Therefore, C.cohnii- derived microalgae biodiesel/petroleum blends of up to 50% are projected to meet all fuel property standards and, engine performance and emission results from this study clearly show its suitability for regular use in diesel engines.

Experimental investigation of the effect of compression ratio on performance and emissions of CI engine operated with waste fried oil methyl ester blend

The aim of the present work is to experimentally investigate the effect of compression ratio on performance of compression ignition engine operated with waste fried oil methyl ester (WFOME) blended with mineral diesel. This paper discusses the results of investigations carried out on a single-cylinder, four-stroke, direct injection, diesel engine operated on WFOME blended with mineral diesel. Compression ratios considered for this analysis were 14.5, 16.5 and 17.5. All tests with different fuels were conducted for constant speed (1500rpm) and with varying loads (0.5kW to 4kW) on the engine. Comparative measures of brake thermal efficiency, brake specific fuel consumption, exhaust gas temperature, particulate matter, NOx and CO have been presented and discussed. Engine performance in terms of higher brake thermal efficiency and lower emissions with different blends of biodiesel (B0, B50 and B70) was observed. The performance parameters for different WFOME blends were found to be very close to diesel and the emission characteristics of engine improved significantly. It was observed from this experimentation that an increase of load leads to a significant increase of break thermal efficiency and decrease in BSFC. The effect of variation in the compression ratio on brake thermal efficiency indicated that higher compression ratios improve the engine efficiency. The best results for BSFC were obtained at increased CR. The results showed that CO and particulate matter emissions decreased while nitrogen oxide emission increased with an increase in CR. For all tested fuels an increase in compression ratio leads to an increase in exhaust gas temperature. The reductions in exhaust emissions and brake specific fuel consumption together with increased brake power, and brake thermal efficiency made the WFOME from waste fried oil a suitable alternative fuel for diesel at higher compression ratios and thus could help in controlling air pollution.

Performance Characteristics of Variable Compression Ratio Engine Using COME Biodiesel

This research work investigates the effects of compression ratio on engine performance characteristics of variable compression ratio engine fuelled with biodiesel. The cottonseed oil methyl ester is blended with neat diesel and used as fuel at different compression ratios i.e., 18, 19, 20, 21 and 22. The analyses of engine performances characteristics were carried out for different proportions of cottonseed oil methyl ester blends (b25, b50, b75 and b100). It is inferred that at higher compression ratio, the brake thermal efficiency attained is higher when compared to compression ratio 18. The brake specific fuel consumption for the increment of compression ratio is found to be lower at all blend ratios. The higher brake thermal efficiency was found for b50 at CR 21. It is evident that the exhaust gas temperature reduced with the increment of CR.

Combustion characteristics of the direct injection diesel engine fuelled with corn oil methyl ester

Petroleum-based fuels is a finite resource that is rapidly depleting. Consequently, petroleum reserves are not sufficient enough to last many years. In this research, an experimental investigation has been performed to give insight into the potential of biodiesel as an alternative fuel for direct injection (DI) diesel engines. The experimental work has been carried out to estimate the combustion characteristics of a single-cylinder, four-stroke, DI diesel engine fuelled with corn oil methyl ester (COME) and diesel blends. The COME was preheated to temperatures namely 50°C, 70°C and 90°C before it was supplied to the engine. The optimised preheated temperature of 70°C was chosen based on the higher brake thermal efficiency and lower specific fuel consumption. The performance, emission and combustion characteristics are evaluated by running the engine with COME and diesel blends at this preheated temperature. In this paper, the combustion characteristics are only discussed. The combustion characteristics such as ignition delay, maximum rate of pressure, heat release rate, cumulative heat release rate, mass fraction burned and combustion duration of COME methyl ester and diesel were evaluated and compared with neat diesel. The rate of pressure rise and maximum combustion pressure inside the cylinder were high for COME blends compared with neat diesel. The heat release rate of diesel is higher compared with COME blends. The ignition delay and combustion duration are decreased for COME blends compared with neat diesel. The cumulative heat release rate and mass fraction burnt of COME blends are higher than neat diesel.

Investigation of emissions and combustion characteristics of a CI engine fueled with waste cooking oil methyl ester and diesel blends

Biodiesel has been identified as a potential alternative fuel for CI engines because use of biodiesel can reduce petroleum diesel consumption as well as engine out emissions. Out of many biodiesel derived from various resources, biodiesel from Waste Cooking Oil (WCO) can be prepared economically using usual transesterification process. In the present study, in-depth research and comparative study of blends of biodiesel made from WCO and diesel is carried out to bring out the benefits of its extensive usage in CI engines. The experimental results of the study reveal that the WCO biodiesel has similar characteristics to that of diesel. The brake thermal efficiency, carbon monoxide, unburned hydrocarbon and smoke opacity are observed to be lower in the case of WCO biodiesel blends than diesel. On the other hand specific energy consumption and oxides of nitrogen of WCO biodiesel blends are found to be higher than diesel. In addition combustion characteristics of all biodiesel blends showed similar trends when compared to that of conventional diesel.

Effect of Compression Ratio on Emission of CI Engine using Neat Karanja Oil and Karanja Oil Methyl Ester Blends

The standard design parameters of a compression ignition engine fail to give specified performance with strait vegetable oil (SVO) from different origins. This study is performed to find the effect of compression ratio on emission characteristics such as carbon monoxide (CO), carbon dioxide (CO2), hydrocarbon (HC), nitrogen oxides (NOx) and smoke opacity with all the tested fuels in a single cylinder, four stroke VCR engine fueled with neat Karanja oil blends (10 and 20%) with diesel (on volume basis) and Karanja oil methyl ester (KOME) blends (20, 40 and 60%) and compare the results with diesel. Experiments haves been conducted at compression ratios of 16:1, 17:1, 18:1. At higher CR, minimum value of CO is recorded as being 0.04 for 20% blend of KOME (B20), while maximum CO2 is4.45%. Lowest HC and NOx emission recorded are 22 ppm and 552 ppm respectively for 40% blend of KOME (B40). Emissions are marginally higher for K10 and K20 than for diesel. Overall observation shows that B40 has the lowest emissions among other blends of KOME at higher compression ratios.

Investigations on the Effect of Waste Fried Oil Methyl Ester Blends and Load on Performance and Smoke Opacity of Diesel Engine Using Response Surface Methodology

Aim of this study was to investigate effect of parameters like blend and load on the performance and emission characteristics of single cylinder direct injection diesel engine using waste fried oil methyl ester (WFOME). As far as the application in rural agricultural sector of a developing country is concerned, such engines should preferably utilize alternative fuels of bio-origin, which are locally available. Two input parameters, that is, blend and load, were varied and responses such as Brake Thermal Efficiency (BTE), Brake Specific Fuel Consumption (BSFC), Exhaust Gas Temperature (EGT), and smoke opacity(OP) were investigated. Response Surface Methodology (RSM) was employed for modeling and analysis of response parameters to evaluate the characteristics of the engine. The experiments were designed using a statistical tool known as Design of Experiments (DoE) based on RSM. Engine-operating parameters were optimized using the Desirability approach of RSM.Finally, model optimized results were validated experimentally. The performance parameters for different WFOME blends were found close to diesel, and emission characteristics of the engine improved significantly. A blend of B20 and brake load of 2.5kW were found to be optimal input parameters for the WFOME blended with diesel in the test engine of 5 HP at 1500rpm.

The Effects in Performance and Emissions of DI Diesel Engine Using Biodiesel (PPME) – Blends as Fuel

In the present work biodiesel derived from non edible oil with diesel was used to study the performance of DI Diesel engine at 200 bar injection pressure and 1500rpm. Experiments were carried out with Pogamia Pinnata oil Methyl Ester (POME) and diesel blends in different proportions to reduce tail pipe emissions. Comparative study is conducted using diesel, bio-diesel and with various blends of biodiesel. POME is used (diesel, 20, 40, 60, 80, 100) with various percentages by volume for all loads (0, 3, 6, 9 and 12kg load). The performance of the engine is compared with neat diesel in respect of brake thermal efficiency, BSFC and exhaust emissions.

The Performance and Emission Characteristics of Fish Oil Methyl Esters (Fome) and Diesel Blends in a Partially Premixed Charge Compression Ignition Engine

In the present work, an attempt was made to reduce NOx and PM using partially premixed charge compression ignition (PPCCI) combustion of diesel fuel with external mixture formation technique and fish oil methyl ester (FOME) blend in the main injection. Not much work has been done related to the usage of bio-diesel (Methyl esters of edible, non-edible oils, and animal fats) in the PPCCI combustion mode. Diesel fuel was injected into the intake manifold to form homogeneous pre-mixture beforehand and the pre-mixture is burnt in the cylinder with the balance quantity of fuel directly injected into the cylinder by a conventional injection system. To obtain homogeneous mixture, diesel fuel was injected in the intake manifold using a solenoid-operated injector controlled by Electronic Control Unit (ECU). Exhaust Gas Recirculation (EGR) technique was adopted to control the start of combustion (SOC). Experiments were conducted with 10%, 20%, and 30% EGR for premixed ratio (Rp) 25% and results are compared with conventional diesel fuel operation. It is observed that diesel manifold injection and FOME blend in main injection results in better mixture preparation and lower emissions. Due to homogenous lean operation, significant reduction in NOx and PM are achieved with the PPCCI combustion mode at Rp 25% and EGR 20% in the FOME-Diesel mode of operation.

Performance and Emission Analysis of a CI Engine in Dual Mode with LPG and Karanja Oil Methyl Ester

The use of liquefied petroleum gas (LPG) is experimented with to improve the performance of a dual fuel compression ignition (CI) engine running on Karanja oil methyl ester (KOME) blends. Diesel is used as a reference fuel for the dual fuel engine results. During the experimentation, the engine performance is measured in terms of brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC), and exhaust emission is measured in terms of carbon monoxide (CO), hydrocarbon (HC), and oxides of nitrogen (). Dual fuel engine with LPG showed a reduction in and smoke emission; however, it suffers from high HC and CO emission, particularly, at lower loads due to poor ignition. Comparison of performance and emissions is done for diesel and blends of KOME. Results showed that using KOME blends (10% and 20%) has improved the CI engine performance with a reduction in HC and CO emissions.

Performance and combustion characteristics of a diesel engine with titanium oxide coated piston using Pongamia methyl ester

Owing to the increasing cost of petroleum products, fast depletion of fossil fuel, environmental consideration and stringent emission norms, it is necessary to search for alternative fuels for diesel engines. The alternative fuel can be produced from materials available within the country. Though the vegetable oils can be fuelled for diesel engines, their high viscosities and low volatilities have led to the investigation of its various derivatives such as monoesters, known as bio diesel. It is derived from triglycerides (vegetable oil and animal fates) by transesterification process. It is biodegradable and renewable in nature. Biodiesel can be used more efficiently in semi adiabatic engines (Semi LHR), in which the temperature of the combustion chamber is increased by thermal barrier coating on the piston crown. In this study, the piston crown was coated with ceramic material (TiO2) of about 0.5 mm, by plasma spray method. In this present work, the experiments were carried out with of Pongamia oil methyl (PME) ester and diesel blends (B20 & B100) in a four stroke direct injection diesel engine with and without coated piston at different load conditions. The results revealed 100% bio diesel, an improvement in brake thermal efficiency (BTE) and the brake specific fuel consumption decreased by about 10 % at full load. The exhaust emissions like carbon monoxide (CO) and hydrocarbon (HC) were decreased and the nitrogen oxide (NO) emission increased by 15% with coated engine compared with the uncoated engine with diesel fuel. The peak pressure and heat release rate were increased for the coated engine compared with the standard engine.

Combined effect of injection timing, EGR and injection pressure in reducing the NOx emission of a biodiesel blend

In this study, an attempt was made to reduce the higher oxides of nitrogen (NOx) emission of a crude rice bran oil methyl ester (CRBME) blend through modification of combustion process by retarding fuel injection timing and exhaust gas recirculation at an increased fuel injection pressure. At modified condition, delay period and peak pressure of CRBME blend were lower than those at normal condition. The occurrence of maximum heat release rate retarded with a higher magnitude when compared with normal condition. Experimental results show that as a result of combustion modification, NOx and carbon monoxide emissions were reduced significantly with marginal increase in smoke density. Brake thermal efficiency and unburnt hydrocarbon emissions of the engine were increased significantly as a result of this modification process. This investigation shows that the NOx emission of a biodiesel blend can be reduced with less sacrifice on smoke density and increase in the brake thermal efficiency by modifying the combustion process.

Performance and Emission Studies of Castor Bean (Ricinus Communis) Oil Biodiesel and Its Blends with Diesel Fuel

An experimental study was conducted to evaluate the use of various blends of castor (Ricinus Communis) oil methyl ester with diesel fuel. Performance and exhaust emissions of castor oil biodiesel with diesel fuel in a commercial compression ignition engine were presented in this study. Biodiesel produced from castor oil was blended with diesel fuel at the volumetric ratios of 5% (B5), 10% (B10), 25% (B25), 50% (B50), and 100% (B100). Fuel properties of castor oil methyl ester and its blends with diesel fuel were stated. The performance results showed that blends of castor oil methyl ester with diesel provided an increase on brake specific fuel consumption and a small decrease on brake power output. Compared with diesel fuel, diesel-castor oil methyl ester blends showed that while the carbon monoxide and carbon dioxide emissions became reduced; the oxides of nitrogen emissions observed higher than diesel fuel emission characteristics. Test results showed that B25 was determined as a suitable alternative fuel for diesel engines.

Variation of performance and emission characteristics of a diesel engine fueled with diesel, rapeseed oil and hazelnut oil methyl ester blends

Abstract Turkey's economy is mainly dependent on agriculture and the country provides almost all petroleum demand through imports, the evaluation of vegetable alternative engine fuels is of great importance. In this study, usability of methyl ester of rapeseed oil and hazelnut produced abundant in Turkey was examined. Experiments were carried out in a four-cylinder, four-stroke, 46 kW, direct injection diesel engine. A comparison of diesel fuel, the rapeseed oil methyl ester and the hazelnut oil methyl ester blends was made from the engine performance and emissions point of view. Engine performance and emission tests were carried out with 4 different fuel that 100% diesel (SD), 50% rapeseed oil methyl ester and 50% diesel (B1), 50% hazelnut oil methyl ester and %50 diesel (B2), 25% rapeseed oil methyl ester, 25% rapeseed oil methyl ester and 50% diesel (B3). Highest engine performance and lowest specific fuel consumption were obtained with SD fuel. But the use of biodiesel led to reduction in CO and smoke emissions accompanying with the imperceptible torque loss. As the rapeseed methyl ester rate increased in the blend, smoke and CO emissions decreased, NOx and CO2 emissions increased. With the use of B1 fuel, NOx emissions increased up to 7.2%.

Application of Taguchi’s Orthogonal Array in Multi Response Optimization of NO<sub>x</sub> Emission of Crude Rice Bran Oil Methyl Ester Blend as a CI Engine Fuel

In this work an attempt was made to minimize the NOx emission of a crude rice bran oil methyl ester (CRBME) blend with less sacrifice on smoke density and brake thermal efficiency. Three factors namely fuel injection timing, percentage EGR and fuel injection pressure were chosen as the influencing factors for the set objective. Experiments were designed by employing design of experiments method and Taguchi’s L9 orthogonal array was used to test the engine. MRSN ratio was calculated for the response variables and the optimum combination level of factors was obtained simultaneously using Taguchi’s parametric design. ANOVA was employed to analyze the variance of MRSN and the most influencing factor for the set objective was taken from the ANOVA table. Obtained combination was confirmed experimentally and significant improvement was observed in the response variables.

Air and noise pollution of a diesel engine fueled with olive pomace oil methyl ester and petrodiesel blends

Olive pomace oil derives from the oil left in the olive fruit pulp than remains after pressing extra virgin olive oil. To extract olive pomace oil, the pulp is treated with solvents. The resultant oil contains impurities and may undergo several heating and filtering processes to refine it to an acceptable standard. To make it satisfactory to consumers, it must be blended with virgin olive oil before use. Therefore, another uses for this oil could be soap production or its recycling to produce biodiesel. Exhaust emissions, noise and sound quality of a direct injection diesel engine fueled with olive pomace oil methyl ester (OPME) blends were studied at several steady-state engine operating conditions. Results showed that the higher the content of OPME in the blends, the lower the CO emissions, whereas NOx increased, keeping fuel consumption constant. Moreover, it was found that cetane number exhibited a stronger effect over noise production than bulk modulus, whereas the reverse effect was found concerning NOx emissions. Biodiesel blends reduced air and noise pollution, while improving sound quality. Therefore, the higher the percentage of biodiesel in blends, the lower the pollution emitted by the engine.

Use of Palm oil Biodiesel Blends as a Fuel for Compression Ignition Engine

Problem statement: The increasing awareness of the environmental hazards and the alarming levels of air pollution have led to more restrictive regulations on engines emission control in recent years. Approach: The dwindling resources and rising cost of crude oil had resulted in an intensified search for alternate fuels. In the present study biodiesel (palm oil methyl ester) blends with diesel was investigated in a direct injection stationary diesel engine. The stationary engine test bed used consists of a single-cylinder four stroke diesel engine, eddy current dynamometer with computer control data acquisition system and exhaust emissions analyzer. Results: Engine tests were conducted at constant speed using neat diesel fuel and various proportions of biodiesel blends. The exhaust emissions such as CO, HC and NOx were measured using exhaust gas analyzer. Performance characteristics like brake thermal efficiency and specific fuel consumption were recorded. The differences in the measured emissions and performance of the biodiesel-diesel fuel blends from the baseline operation of the engine, i.e., when working with neat diesel fuel were determined and compared. Conclusion: It is concluded that the lower blends of biodiesel increased the brake thermal efficiency and reduced the fuel consumption. Biodiesel blends produces lower engine emissions than diesel. From the result, it has been established that 20-40% of palm oil biodiesel can be use as a substitute for diesel without any engine modifications.

Characterizing priority polycyclic aromatic hydrocarbons (PAH) in particulate matter from diesel and palm oil-based biodiesel B15 combustion

A set of 16 priority polycyclic aromatic hydrocarbons (PAH) associated with particulate matter (PM), emitted by a diesel engine fueled with petroleum diesel and a 15%-vol. palm oil methyl ester blend with diesel (B15), were determined. PM was filtered from a sample of the exhaust gas with the engine running at a steady speed and under no load. PAH were extracted from the filters using the Soxhlet technique, with dichloromethane as solvent. The extracts were then analyzed by gas chromatography using a flame ionization detector (FID). No significant difference was found between PM mass collected when fueled with diesel and B15. Ten of the 16 PAH concentrations were not reduced by adding biodiesel: Benz(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, chrysene, dibenz(a,h)anthracene, fluoranthene, fluorene, indeno(1,2,3-c,d)pyrene, naphthalene and phenanthrene. The acenaphthene, acenaphthylene and anthracene concentrations were 45%–80% higher when using diesel, whereas those for benzo(k)fluoranthene, benzo(g,h,i)perylene and pyrene were 30%–72% higher when using the B15 blend. Even though the 16 priority-PAH cumulative concentration increased when using the B15 blend, the total toxic equivalent (TEQ) concentration was not different for both fuels.