Application of JP-8 in a heavy duty diesel engine

An experimental study was carried out to investigate the combustion and emission of JP-8 and diesel fuel in an optically-accessible single-cylinder heavy duty diesel engine equipped with a high pressure common-rail injection system in order to evaluate the feasibility of JP-8 application in diesel engine. The basic spray characteristics, including spray tip penetration and spray angle, were investigated with macroscopic spray images obtained by the Mie-scattering method. The combustion and emission characteristics were analyzed on the basis of the results obtained from the spray experiments. Visualization by direct imaging was used to characterize the combustion process.It was found that JP-8 had a shorter spray tip penetration and wider spray angle than diesel fuel mainly due to the faster vaporization characteristic of JP-8. The peak heat release rate was higher and the premixed burn portion was larger with JP-8 due to its superior mixing rate through faster vaporization characteristics. Furthermore, ignition delay with JP-8 was longer than that with diesel fuel due to the lower cetane number of JP-8. In terms of emission, JP-8 showed a benefit in smoke reduction while it produced larger amounts of HC and NO_x. Longer ignition delay and accelerated oxidation in the late stage of JP-8 combustion were verified by direct imaging.     

Effects of biodiesel on a DI diesel engine performance, emission and combustion characteristics

Experimental tests were investigated to evaluate the performance, emission and combustion of a diesel engine using neat rapeseed oil and its blends of 5%, 20% and 70%, and standard diesel fuel separately. The results indicate that the use of biodiesel produces lower smoke opacity (up to 60%), and higher brake specific fuel consumption (BSFC) (up to 11%) compared to diesel fuel. The measured CO emissions of B5 and B100 fuels were found to be 9% and 32% lower than that of the diesel fuel, respectively. The BSFC of biodiesel at the maximum torque and rated power conditions were found to be 8.5% and 8% higher than that of the diesel fuel, respectively. From the combustion analysis, it was found that ignition delay was shorter for neat rapeseed oil and its blends tested compared to that of standard diesel. The combustion characteristics of rapeseed oil and its diesel blends closely followed those of standard diesel.     

PAH and other emissions from burning of JP-8 and diesel fuels in diffusion flames

Jet fuel JP-8 is of technical interest to the military aviation industry. JP-8 is now the single battlefield fuel for all US Army and Air Force equipment, replacing gasoline altogether and gradually replacing diesel fuel. Hence, emissions from the combustion of this fuel are the subject for this investigation. The emissions from the combustion of JP-8 fuel are examined and are compared to those from diesel fuel No. 2, burned under identical conditions. Combustion occurred inside a laboratory furnace in sooty diffusion flames, under adverse conditions that typically emit large amounts of products of incomplete combustion (PIC). Under such conditions, even compounds that otherwise might appear only in trace amounts were present in sufficient quantities for detection. The study reports on emissions of CO, light volatile organic compounds, semi-volatile organic compounds with an emphasis on polycyclic aromatic hydrocarbons (PAH), particulate emissions, oxides of nitrogen (NO_x) and oxides of sulfur (SO₂). Some PAH compounds are suspected of posing a threat to human health, benzo[a]pyrene being listed as a bio-accumulative toxin by the EPA. An afterburner was also used to examine the effects of longer furnace residence time. Results have demonstrated that PAH emissions from the combustion of diesel fuel were higher than those of JP-8, under most conditions examined. Moreover, as the temperature of the primary furnace was increased, in the range of 600–1000 °C, most of the emissions from both fuels increased. Particulate emissions were reduced by the afterburner, which was operated at 1000 °C, only when the primary furnace was operated at the lowest temperature (600 °C), but that condition increased the CO emissions. Overall, transient combustion of these two fuels, burning in laminar and sooty diffusion flames, did not reveal major differences in the emissions of the following PIC: C1–C4 light aliphatic hydrocarbons, PAH, CO and particulate matter.     

Comparison of emissions of a direct injection diesel engine operating on biodiesel with emulsified and fumigated methanol

Biodiesel is an alternative fuel for internal combustion engines. It can reduce carbon monoxide (CO), hydrocarbon (HC) and particulate matter (PM) emissions, compared with diesel fuel, but there is also an increase in nitrogen oxides (NO_x) emission. This study is aimed to compare the effect of applying a biodiesel with either 10% blended methanol or 10% fumigation methanol. The biodiesel used in this study was converted from waste cooking oil. Experiments were performed on a 4-cylinder naturally aspirated direct injection diesel engine operating at a constant speed of 1800 rev/min with five different engine loads. The results indicate a reduction of CO₂, NO_x, and particulate mass emissions and a reduction in mean particle diameter, in both cases, compared with diesel fuel. It is of interest to compare the two modes of fueling with methanol in combination with biodiesel. For the blended mode, there is a slightly higher brake thermal efficiency at low engine load while the fumigation mode gives slightly higher brake thermal efficiency at medium and high engine loads. In the fumigation mode, an extra fuel injection control system is required, and there is also an increase in CO, HC and NO₂ (nitrogen dioxide) and particulate emissions in the engine exhaust, which are disadvantages compared with the blended mode.     

Phase stability,fuel properties,and diesel engine performance of palm-oil-based microemulsion biofuels

Microemulsification and blending are two viscosity-modifying techniques of vegetable oils for direct use with diesel engine. In this study, alcohol blends are mixtures of ethanol, diesel, and palm-oil biodiesel while microemulsion biofuels are thermodynamically stable, clear, and single-phase mixtures of diesel, palm oil, and ethanol stabilized by surfactants and cosurfactants. Although there are many studies on biofuels lately, there is limited research on using biodiesel as a surfactant in microemulsion formulations and applied on engine performance at different engine loads. Therefore, the objectives are to investigate phase stability and fuel properties of formulated biofuels (various blends and microemulsions), to determine the engine performance at different engine loads (no load, and from 0.5 to 2.0 kW), and to estimate laboratory-scale cost of the selected biofuels compared to diesel and biodiesel. The results showed that phase stability and fuel properties of selected microemulsion biofuels are comparable to diesel and biodiesel. These microemulsion biofuels can be applied to the diesel engine at different loads while diesel-ethanol blends and palm-oil-biodiesel-ethanol blends cannot be. It was found that the energy efficiencies of the system using microemulsion biofuels were slightly lower than the average energy efficiency of diesel engine. From this study, it can be summarized that microemulsion biofuels can be formulated using palm-oil biodiesel (palm-oil methyl ester) as a bio-based surfactant and they can be considered as environmentally-friendly alternatives to diesel and biodiesel. However, cost considerations showed that the raw materials should be locally available to reduce additional costs of microemulsion biofuels.     

Effect of altitude and palm oil biodiesel fuelling on the performance and combustion characteristics of a HSDI diesel engine

Altitude above sea level and fuel’s chemical and physical nature affect engine performance and combustion characteristics. In this work, a combustion diagnosis model including exergy analysis was applied to a turbocharged (TC) automotive diesel engine fuelled with neat palm oil biodiesel (B100) and No. 2 diesel fuel (B0). Tests were performed under steady state operating conditions, at two altitudes above sea level: 500 and 2400 m. Biodiesel fuelling and altitude had an additive effect on the advance in injection and combustion timings. The duration of the premixed combustion stage increased with altitude and decreased with biodiesel. When B100 was used, the transition between this stage and the diffusion stage was practically suppressed. As altitude increased, biodiesel fuelling led to shorter combustion duration, and higher in-cylinder pressures and fuel-air equivalence ratios. Brake thermal efficiency decreased with altitude for both fuels, but in a greater extent for B0. For all fuels and altitudes, exergy destruction rose sharply when combustion started, indicating that this process was the main source of irreversibilities. At both altitudes, the cumulative exergy destruction was higher for B100 due to its earlier and faster combustion process. Some of the results obtained in this work indicate that palm oil biodiesel fuelling can lead to a better engine performance at high altitudes.     

Ethanol animal fat emulsions as a diesel engine fuel – Part 2: Engine test analysis

This work aims on the efficient use of animal fat in a diesel engine by making its stable emulsions with ethanol and water. A single cylinder direct injection diesel engine is tested using neat diesel, neat animal fat and animal fat emulsion (optimal emulsion) as fuels under variable load operating conditions. Results show increased peak pressure and ignition delay with ethanol animal fat emulsion as compared to neat fat. Heat release pattern shows improvement in the premixed combustion phase with animal fat emulsion as compared to neat animal fat. Drastic reduction in smoke, nitric oxide, hydrocarbon and carbon monoxide emissions are observed with the emulsion as compared to neat fat and neat diesel mainly at high power outputs. Only, hydrocarbon and carbon monoxide emissions are found as high with the emulsion at light loads. In general, animal fat emulsion shows considerable reduction in all emissions and improvement in engine performance as compared to neat fat.     

The influence of operating parameters on the performance and emissions of a DI diesel engine using methanol-blended-diesel fuel

In this study, the effects of injection pressure and timing on the performance and emission characteristics of a DI diesel engine using methanol (5%, 10% and 15%) blended-diesel fuel were investigated. The tests were conducted on three different injection pressures (180, 200 and 220 bar) and timings (15°, 20°, and 25° CA BTDC) at 20 Nm engine load and 2200 rpm. The results indicated that brake specific fuel consumption (BSFC), brake specific energy consumption (BSEC), and nitrogen oxides (NO_x) emissions increased as brake thermal efficiency (BTE), smoke opacity, carbon monoxide (CO) and total unburned hydrocarbon (THC) decreased with increasing amount of methanol in the fuel mixture. The best results were achieved for BSFC, BSEC and BTE at the original injection pressure and timing. For the all test fuels, the increasing injection pressure and timing caused to decrease in the smoke opacity, CO, THC emissions while NO_x emissions increase.     

Potential for reducing emissions in a diesel engine by fuelling with conventional biodiesel and Fischer-Tropsch diesel

A gas-to-liquid (GTL) fuel derived from Low Temperature Fischer-Tropsch process has been tested in an automotive diesel engine fulfilling Euro 4 emissions regulations. Both regulated and non-regulated emissions have been compared with those of a commercial diesel fuel, a commercial biodiesel fuel and a GTL-biodiesel fuel (30% and 70% v/v, respectively) in order to check blending properties, synergistic effects and compatibility between first and second generation production technologies for biofuel consumption in current diesel engines. After presenting a detailed literature review, and confirming that similar efficiencies are attained with the four tested fuels under identical road-like operating conditions (this meaning fuel consumption is inversely proportional to their heating values), significant reductions in smoke opacity, particulate matter emissions and particle number concentration were observed with both GTL and biodiesel fuels, with small changes in NO_x emissions. Compared with the reductions in PM emissions derived from the use of biodiesel fuels, those derived from using GTL fuels were quite similar, despite its lower soot emissions reductions. This can be explained by the lower volatile organic fraction of the PM in the case of GTL. By adequately blending both fuels, a considerable potential to optimise the engine emissions trade-off is foreseen.     

Characteristics of polycyclic aromatic hydrocarbons emissions of diesel engine fueled with biodiesel and diesel

With mutagenic and carcinogenic potential, polycyclic aromatic hydrocarbons (PAHs) from mobile source exhaust have contributed to a substantial share of air toxics. In order to characterize the PAHs emissions of diesel engine fueled with diesel, biodiesel (B100) and its blend (B20), an experimental study has been carried out on a direct-injection turbocharged diesel engine. The particle-phase and gas-phase PAHs in engine exhaust were collected by fiberglass filters and “PUF/XAD-2/PUF” cartridges, respectively, then the PAHs were determined by a gas chromatograph/mass spectrometer (GC/MS). The experimental results indicated that comparing with diesel, using B100 and B20 can greatly reduce the total PAHs emissions of diesel engine by 19.4% and 13.1%, respectively. The Benzo[a]Pyrene (BaP) equivalent of PAHs emissions were also decreased by 15.0% with the use of B100. For the three fuels, the gas-phase PAHs emissions were higher than particle-phase PAHs emissions and the most abundant PAH compounds from engine exhaust were naphthalene and phenanthrene. The analysis showed that there was a close correlation between total PAHs emissions and particulate matter (PM) emissions for three fuels. Furthermore, the correlation became more significant when using biodiesel.     

Emission characteristics of high speed, dual fuel, compression ignition engine operating in a wide range of natural gas/diesel fuel proportions

In the effort to reduce pollutant emissions from diesel engines various solutions have been proposed, one of which is the use of natural gas as supplement to liquid diesel fuel, with these engines referred to as fumigated, dual fuel, compression ignition engines. One of the main purposes of using natural gas in dual fuel (liquid and gaseous one) combustion systems is to reduce particulate emissions and nitrogen oxides. Natural gas is a clean burning fuel; it possesses a relatively high auto-ignition temperature, which is a serious advantage over other gaseous fuels since then the compression ratio of most conventional direct injection (DI) diesel engines can be maintained high. In the present work, an experimental investigation has been conducted to examine the effects of the total air-fuel ratio on the efficiency and pollutant emissions of a high speed, compression ignition engine located at the authors’ laboratory, where liquid diesel fuel is partially substituted by natural gas in various proportions, with the natural gas fumigated into the intake air. The experimental results disclose the effect of these parameters on brake thermal efficiency, exhaust gas temperature, nitric oxide, carbon monoxide, unburned hydrocarbons and soot emissions, with the beneficial effect of the presence of natural gas being revealed. Given that the experimental measurements cover a wide range of liquid diesel supplementary ratios without any appearance of knocking phenomena, the belief is strengthened that the findings of the present work can be very valuable if opted to apply this technology on existing DI diesel engines.     

The influence of n-butanol/diesel fuel blends utilization on a small diesel engine performance and emissions

Nitrogen oxides and smoke emissions are the most significant emissions for the diesel engines. Especially, fuels containing high-level oxygen content can have potential to reduce smoke emissions significantly. The aim of the present study is to evaluate the influence of n-butanol/diesel fuel blends (as an oxygenation additive for the diesel fuel) on engine performance and exhaust emissions in a small diesel engine. For this aim five-test fuels, B5 (contains 5% n-butanol and 95% diesel fuel in volume basis), B10, B15, B20 and neat diesel fuel, were prepared to test in a diesel engine. Tests were performed in a single cylinder, four stroke, unmodified, and naturally aspirated DI high speed diesel engine at constant engine speed (2600 rpm) and four different engine loads by using five-test fuels. The experimental test results showed that smoke opacity, nitrogen oxides, and carbon monoxide emissions reduced while hydrocarbon emissions increased with the increasing n-butanol content in the fuel blends. In addition, there is an increase in the brake specific fuel consumption and in the brake thermal efficiency with increasing n-butanol content in fuel blends. Also, exhaust gas temperature decreased with increasing n-butanol content in the fuel blends.     

Biodiesel from safflower oil and its application in a diesel engine

Safflower seed oil was chemically treated by the transesterification reaction in methyl alcohol environment with sodium hydroxide (NaOH) to produce biodiesel. The produced biodiesel was blended with diesel fuel by 5% (B5), 20% (B20) and 50% (B50) volumetrically. Some of important physical and chemical fuel properties of blend fuels, pure biodiesel and diesel fuel were determined. Performance and emission tests were carried out on a single cylinder diesel engine to compare biodiesel blends with petroleum diesel fuel. Average performance reductions were found as 2.2%, 6.3% and 11.2% for B5, B20 and B50 fuels, respectively, in comparison to diesel fuel. These reductions are low and can be compensated by a slight increase in brake specific fuel consumption (Bsfc). For blends, Bsfcs were increased by 2.8%, 3.9% and 7.8% as average for B5, B20 and B50, respectively. Considerable reductions were recorded in PM and smoke emissions with the use of biodiesel. CO emissions also decreased for biodiesel blends while NO_x and HC emissions increased. But the increases in HC emissions can be neglected as they have very low amounts for all test fuels. It can be concluded that the use of safflower oil biodiesel has beneficial effects both in terms of emission reductions and alternative petroleum diesel fuel.     

Performance and emission study of waste anchovy fish biodiesel in a diesel engine

Waste anchovy fish oils transesterification was studied with the purpose of achieving the conditions for biodiesel usage in a single cylinder, direct injection compression ignition. With this purpose, the pure biodiesel produced from anchovy fish oil, biodiesel-diesel fuel blends of 25%:75% biodiesel-diesel (B25), 50%:50% biodiesel-diesel (B50), 75%:25% biodiesel-diesel (B75) and petroleum diesel fuels were used in the engine to specify how the engine performance and exhaust emission parameters changed. The fuel properties of test fuels were analyzed. Tests were performed at full load engine operation with variable speeds of 1000, 1500, 2000 and 2500 rpm engine speeds. As results of investigations on comparison of fuels with each other, there has been a decrease with 4.14% in fish oil methyl ester (FOME) and its blends' engine torque, averagely 5.16% reduction in engine power, while 4.96% increase in specific fuel consumption have been observed. On one hand there has been average reduction as 4.576%, 21.3%, 33.42% in CO₂, CO, HC, respectively; on the other hand, there has been increase as 9.63%, 29.37% and 7.54% in O₂, NO_x and exhaust gas temperature has been observed. It was also found that biodiesel from anchovy fish oil contains 37.93 wt.% saturated fatty acids which helps to improve cetane number and lower NO_x emissions. Besides, for biodiesel and its blends, average smoke opacity was reduces about 16% in comparison to D2. It can be concluded that waste anchovy fish obtained from biodiesel can be used as a substitute for petroleum diesel in diesel engines.     

Fuel properties and emissions of soybean oil esters as diesel fuel

The effects of using blends of methyl and isopropyl esters of soybean oil with No. 2 diesel fuel were studied at several steady-state operating conditions in a four-cylinder turbocharged diesel engine. Fuel blends that contained 20, 50, and 70% methyl soyate and 20 and 50% isopropyl soyate were tested. Fuel properties, such as cetane number, also were investigated. Both methyl and isopropyl esters provided significant reductions in particulate emissions compared with No. 2 diesel fuel. A blend of 50% methyl ester and 50% No. 2 diesel fuel provided a reduction of 37% in the carbon portion of the particulates and 25% in the total particulates. The 50% blend of isopropyl ester and 50% No. 2 diesel fuel gave a 55% reduction in carbon and a 28% reduction in total particulate emissions. Emissions of carbon monoxide and unburned hydrocarbons also were reduced significantly. Oxides of nitrogen increased by 12%.     

Comparative study of performance and emissions of a diesel engine using Chinese pistache and jatropha biodiesel

An experimental study of the performances and emissions of a diesel engine is carried out using two different biodiesels derived from Chinese pistache oil and jatropha oil compared with pure diesel. The results show that the diesel engine works well and the power outputs are stable running with the two selected biodiesels at different loads and speeds. The brake thermal efficiencies of the engine run by the biodiesels are comparable to that run by pure diesel, with some increases of fuel consumptions. It is found that the emissions are reduced to some extent when using the biodiesels. Carbon monoxide (CO) emissions are reduced when the engine run at engine high loads, so are the hydrocarbon (HC) emissions. Nitrogen oxides (NOx) emissions are also reduced at different engine loads. Smoke emissions from the engine fuelled by the biodiesels are lowered significantly than that fuelled by diesel. It is also found that the engine performance and emissions run by Chinese pistache are very similar to that run by jatropha biodiesel.     

Experimental investigation on dual fuel operation of acetylene in a DI diesel engine

Depletion of fossils fuels and environmental degradation have prompted researchers throughout the world to search for a suitable alternative fuel for diesel engine. One such step is to utilize renewable fuels in diesel engines by partial or total replacement of diesel in dual fuel mode. In this study, acetylene gas has been considered as an alternative fuel for compression ignition engine, which has excellent combustion properties.Investigation has been carried out on a single cylinder, air cooled, direct injection (DI), compression ignition engine designed to develop the rated power output of 4.4 kW at 1500 rpm under variable load conditions, run on dual fuel mode with diesel as injected primary fuel and acetylene inducted as secondary gaseous fuel at various flow rates. Acetylene aspiration resulted in lower thermal efficiency. Smoke, HC and CO emissions reduced, when compared with baseline diesel operation. With acetylene induction, due to high combustion rates, NO_x emission significantly increased. Peak pressure and maximum rate of pressure rise also increased in the dual fuel mode of operation due to higher flame speed. It is concluded that induction of acetylene can significantly reduce smoke, CO and HC emissions with a small penalty on efficiency.     

Effects of ethyl tert-butyl ether addition to diesel fuel on characteristics of combustion and exhaust emissions of diesel engines

The effects of ethyl tert-butyl ether (ETBE) addition to diesel fuel on the characteristics of combustion and exhaust emissions of a common rail direct injection diesel engine with high rates of cooled exhaust gas recirculation (EGR) were investigated. Test fuels were prepared by blending 0, 10, 20, 30 and 40 vol% ETBE to a commercial diesel fuel. Increasing ETBE fraction in the fuel helps to suppress the smoke emission increasing with EGR, but a too high fraction of ETBE leads to misfiring at higher EGR rates. While the combustion noise and NO_x emissions increase with increases in ETBE fraction at relatively low EGR rates, they can be suppressed to low levels by increasing EGR. Though there are no significant increases in THC and CO emissions due to ETBE addition to diesel fuel in a wide range of EGR rates, the ETBE blended fuel results in higher aldehyde emissions than the pure diesel fuel at relatively low EGR rates. With the 30% ETBE blended fuel, the operating load range of smokeless, ultra-low NO_x (<0.5 g/kWi h), and efficient diesel combustion with high rates of cooled EGR is extended to higher loads than with the pure diesel fuel.     

Fuel production from waste vehicle tires by catalytic pyrolysis and its application in a diesel engine

An alternative fuel production was performed by pyrolysis of waste vehicle tires under nitrogen (N₂) environment and with calcium hydroxide (Ca(OH)₂) as catalyst. The sulfur content of liquids obtained were reduced by using Ca(OH)₂. The liquid fuel of waste vehicle tires(TF) was then used in a diesel engine to blend with petroleum diesel fuel by 5%(TF5), 10%(TF10), 15%(TF15), 25%(TF25), 35%(TF35), 50%(TF50), and 75%(TF75) wt. and pure (TF100). Performance characteristics such as engine power, engine torque, brake specific fuel consumption (bsfc) and exhaust temperature and emission parameters such as oxides of nitrogen (NOx), carbon monoxides (CO), total unburned hydrocarbon (HC), sulfur dioxides (SO₂) and smoke opacity of the engine operation with TF and blend fuels of TF-diesel were experimentally investigated and compared with those of petroleum diesel fuel. It was concluded that the blends of pyrolysis oil of waste tires TF5, TF10, TF25 and TF35 can efficiently be used in diesel engines without any engine modifications. However, the blends of TF50, TF75 and TF100 resulted considerably to high CO, HC, SO₂ and smoke emissions.