Standard Diesel Research Articles

Optimization of an Irreversible Diesel Cycle: Experimental Results of a Ceramic Coated Indirect-Injection Supercharged Diesel Engine

In this work, an irreversible dual cycle analysis has been performed for enhancing the characteristics of a low heat rejection (LHR) supercharged single-cylinder indirect-injection (IDI) diesel engine. A relation which gives the maximum power (MP) and the corresponding efficiency has been derived analytically. Optimization of the diesel cycle has been performed for power and thermal efficiency with respect to the pressure ratio and temperature ratio. Optimum values of the pressure ratio and cutoff ratio of the diesel cycle, depending on the temperature ratios, have been derived analytically and compared to the results of an experimental study of the LHR engine, whose optimum performance was obtained by increasing the temperature in the combustion chamber. Effects of a ceramic coating on performance and exhaust emissions in the LHR engine have been compared to those obtained from the standard (STD) diesel engine based on the comparison of the STD and the LHR engines for identical airflow and brake mean effective pressure. Intake pressure was adjusted to give the same air consumption as the corresponding STD engine for the same brake mean effective pressure (BMEP) and engine speed to avoid a reduction in the volumetric efficiency of the LHR engine. In comparison to the STD engine, satisfactory performance was obtained with the LHR engine. Specific fuel consumption was decreased up to 4.5%, and brake efficiency was increased by 1.5%. NOx emissions were increased by 12% because of the higher flame temperature in the LHR engine.

Normal Heptane-Diesel Combustion and Odorous Emissions in Direct Injection Diesel Engines

This study investigated normal heptane (N-heptane)-diesel combustion and odorous emissions in a direct injection diesel engine during and after engine warmup at idling. The odor is a little worse with N-heptane and blends than that of diesel fuel due to overleaning of the mixture. In addition, formaldehyde (HCHO) and total hydrocarbon (THC) in the exhaust increase with increasing N-heptane content. However, 50% and 100% N-heptane showed lower eye irritation than neat diesel fuel. Due to low boiling point of N-heptane, adhering fuel on the combustion chamber wall is small and as a single-component C7 fuel, relatively high volatile components present in the exhaust are low. This may cause lower eye irritation. On the contrary, bulk in-cylinder gas temperature is lower and ignition delay significantly increases for 50% and 100% N-heptane due to the low boiling point, high latent heat of evaporation, and low bulk modulus of compressibility of N-heptane than standard diesel fuel. This longer ignition delay and lower bulk in-cylinder gas temperature of N-heptane blends deteriorate exhaust odor and emissions of HCHO and THC.

Spatial flow velocity distribution around an inlet port/valve annulus

An experimental investigation of the airflow through inlet port of a standard production direct injection diesel engine is presented. The investigation comprises mass flow rate and pressure drop measurements at fixed valve lifts, and spatial distributions of mean and r.m.s. velocity components around the port/valve annulus measured under steady flow conditions by special designed miniature hot-wire anemometer X probe. The results show that the velocity field is distributed non-uniformly across the valve gap and around valve periphery. Nonuniformity is more expressed at higher valve lifts. Flow instability in a jet leaving the port (jet flapping) is also evident since the skewness and kurtosis of the velocity probability distribution function depart from the Gaussian form. The presented experimental method, based on the application of miniature multiple hot-wire probes, makes possible investigation of flow performances of an inlet port and poppet valve assembly of a production engine head without any modification for ensuring an optical access within the port/cylinder.

The effect of temperature and pressure on the physicochemical properties of petroleum diesel oil and biodiesel fuel

Three commercial fuels were studied: biodiesel (based mainly of the fatty acids methyl esters of rapeseed oil), diesel oil Ekodiesel Ultra (standard petroleum diesel oil with sulphur content less than 10mg/kg), and ON BIO 10 (blend of 20vol.% of biodiesel with 80vol.% of standard petroleum diesel oil with sulphur content less than 10mg/kg). The speeds of sound were measured within the temperatures from 293 to 318K and at pressures from 0.1 to 101MPa. The densities and heat capacities were measured under atmospheric pressure in the temperature range from 273 to 363K and 283 to 359K, respectively. Using the experimental results, the physicochemical properties such as: density, isentropic bulk modulus, heat capacity, and isobaric thermal expansion were calculated in the same temperature and pressure range as the speed of sound was measured. The results obtained show that although the bulk modulus of ON BIO 10 is higher than that of diesel oil Ekodiesel Ultra over the whole pressure range, the difference is rather small and can be compensated by temperature. Isobaric thermal expansivity of biodiesel decreases with pressure slightly less than that of the diesel oil Ekodiesel Ultra. It is approximately independent of temperature and composition of the fuel at pressures 40±5MPa.

Raman Microspectroscopic Analysis of Size-Resolved Atmospheric Aerosol Particle Samples Collected with an ELPI: Soot, Humic-Like Substances, and Inorganic Compounds

Raman microspectroscopy and mapping have been applied for the analysis of soot, humic-like substances (HULIS) and inorganic compounds in size resolved samples of air particulate matter collected with an electrical low pressure impactor (ELPI). Using several reference materials, we found that spectral parameters determined by curve fitting with five bands (G, D1-D4) enable a discrimination of soot and HULIS and provide information about the relative abundance and structural order of graphite-like carbon. In particular, the D1 band width exhibited a near-linear negative correlation with the ratio of apparent elemental carbon to total carbon in different types of soot. The ELPI samples of sub-micrometer atmospheric particles exhibited essentially the same Raman spectra and parameters as standard diesel soot. In winter samples this was also the case for larger particles with aerodynamic diameters up to 4 μm. Spring and autumn samples, however, exhibited increased D1 band widths and D3 band intensities, indicating a high prevalence of HULIS in the size range of 2–4 μm. In addition, various nitrates and sulfates (mostly NaNO3 and (NH4)2SO4; some NH4NO3, Ca(NO3)2, Na2SO4, and CaSO4) and small amounts of CaCO3 were detected. Different single- and multi-component spectra indicated the presence of externally and internally mixed particles. The relative abundance of different chemical components in different particle size ranges was quantified in mapping experiments (0–55% NaNO3, 1–15% (NH4)2SO4, 10–45% soot/HULIS, 30–60% highly fluorescent organics). Overall, the results of this study demonstrate that Raman microspectroscopy and mapping can provide qualitative and quantitative information about the composition of ELPI aerosol samples.

Combustion of bio-oil ethanol blends at elevated pressure

This paper reports an investigation on the combustion performance of bio-oil/ethanol blends. Experiments were conducted in a constant volume vessel operating at a pressure of 25 bar and temperature 1100 K. Bio-oil produced via the fast pyrolysis of a spruce feedstock was blended to ethanol to form three stable blends containing 10%, 20% and 40% bio-oil by weight. In addition, ethanol and standard automotive grade diesel were tested as reference fuels. Measured vessel pressure was used in a single-zone heat release analysis, while two-colour optical pyrometry was used to investigate particle loading and temperature. Results show that for similar injections of fuel energy, use of up to 20% bio-oil in ethanol has limited impact on the performance of ethanol while 40% bio-oil in ethanol produced instability in the pressure trace near the end of the combustion process. Burning rates are similar for blends and ethanol. Addition of bio-oil to ethanol was found to increase combustion generated particle load, and this increased with bio-oil concentration, but remained much lower than particle concentration in diesel. Addition of bio-oil also resulted in formation of char particles that appear as luminous clusters outside the boundary of the spray. This suggests these particles will cool rather than oxidize. The presence of unburnt char particles in large numbers may have consequences for bio-oil as an alternative diesel fuel.

Influence of Biodiesel Fuel on the Combustion and Emission Formation in a Direct Injection (DI) Diesel Engine

This paper studies the influence of biodiesel fuel on the combustion and emission formation of two different direct-injected diesel engines, both employing different combustion processes. The research was focused on determining the influence of the specific combustion process on measurement results to ascertain if a generalization of the results is possible or whether they have to be interpreted as specific for specific engines. Standard D2 diesel fuel and commercial 100% biodiesel fuel were used. Tests were executed using both fuels under the same conditions, and exhaust emissions and engine performance were measured and compared. In-cylinder pressure was also acquired, and the rate of heat release curves were computed by means of a zero-dimensional, one-zone combustion model. Some macroparameters of the combustion process were obtained from the heat-release-rate curves. The results obtained for both engines showed that findings regarding the influence of biodiesel fuel on the combustion process and emission formation could not be generalized and had to be interpreted as specific for the particular engine.

Summary of a 12-Year Experiment in the Use of 50% RME Fuel Mixture in Heavy Trucks and Light Vehicles

Experiments on the use of a 50% RME (Rapeseed Oil Methyl Ester ) fuel mixture were conducted at the agricultural cooperative “Champagne Cereales”, over the period 1993-2005. The study was carried out on twenty heavy trucks from EURO 0 to EURO 3 standards, ten light vehicles with indirect injection engines and four light vehicles (“Peugeot 406” and “Citroen C5”) equipped with “common rail” engine and with DPF (diesel particulate filter ). Half of these vehicles used RME50 fuel and performed the same services along with another group of reference vehicles running on standard diesel fuel. The mileage run on RME50 by heavy trucks ranged between 230 000 and 530 000 km. “406” sedan mileage exceeded 230 000 km and “C5” 190 000 km. Consumption was recorded and lubricants were analysed over the twelve-year period. Injection systems were examined and ten heavy truck engines were disassembled for wear and deposits assessment. The use of RME resulted in no notable incident, and its effect on consumption was according to LHV (lower heating value ) variation. Lubricant dilution was observed on some vehicles, and this phenomenon was reinforced by the use of RME. The lower viscosity level did not cause any increase of wear. The assessed engines showed no sign of deposits in rings and crankcases. On the other hand, the use of RME reduced wear on certain heavy trucks due to lower soot contents in the lubricant.

An experimental study to assess the potential of homogeneous charge compression ignition diesel combustion with various fuels for light-duty engines

Single-cylinder engine tests were carried out to assess the potential of homogeneous charge compression ignition (HCCI) diesel combustion compared to the conventional heterogeneous operation mode. For the experiments a single-cylinder engine with a cylinder volume of 0.421 litre was used. Besides the comparison of conventional operation and HCCI operation of the same engine special emphasis was put on the utilization of synthetic fuels such as gas-to-liquid (GtL) or biomass-to-liquid (BtL) fuels. Therefore, in addition to a standard winter diesel, a fuel with mid-sized n-alkanes and mixtures of n-alkanes and aromatic hydrocarbons was used to investigate the influence of different ignitabilities and boiling curves on the combustion. A great advantage of synthetic fuels is the possibility to design them according to the combustion process requirements. In addition, these GtL or BtL fuels will lead to a higher independence from fossil fuels. To assess the potential of HCCI combustion compared to conventional diesel combustion the engine must have the capability to run in both modes. While using the different fuels several engine operation parameters like injection timing and splitting were varied in order to obtain information about their effect on combustion as well as on engine out-emissions. Furthermore, full-load curves for the different fuels were identified to find out where HCCI operation can be applied in an engine map.

173 汎用小型ディーゼル機関を用いた燃焼特性に及ぼす燃料性状の影響について(熱工学II)

173 汎用小型ディーゼル機関を用いた燃焼特性に及ぼす燃料性状の影響について(熱工学II)

One zone thermodynamic model simulation of an ignition compression engine

The thermodynamic performance of an air standard diesel engine with heat transfer and friction term losses is analysed. In this paper a generic methodology is proposed to simulate the static response of an IC engine and show the influence of several engine parameters on the power and efficiency. Moreover it puts in evidence the existence of two optimal engine speeds one relative to maximum power and the second to maximum efficiency.

Preliminary investigation on fuel related properties of clove stem oil–diesel blended fuels and performance parameters of diesel engine

Oil extracted from clove stems was tested for several important fuel properties and compared with standard diesel fuel. The viscosity of this oil lies between the minimum and maximum required values of the standard diesel fuel. It has very low cetane number (CN) and high density. The CN of this oil prohibits its direct use as an alternative fuel in diesel engines, but it could be used in blends with standard diesel fuel, because most of the determined properties of clove stem oil (CSO)-diesel blended fuels were very close to the South African requirements (SABS 324) for automotive standard diesel fuel. Engine tests show that performance parameters of the CSO-diesel blended fuels do not differ greatly from those of the standard diesel fuel. Slight power losses, combined with an increase in fuel consumption, were experienced with CSO-diesel blended fuels. This may be due to the lower heating value of the CSO-diesel blended fuels. Emissions of CO and HC are low for CSO-diesel blended fuels. NO x emissions were increased remarkably when the engine was fuelled with 50% CSO-diesel blended fuel.

Performance, emissions and heat release characteristics of direct injection diesel engine operating on diesel oil emulsion

Emulsions of diesel and water are often promoted as being able to overcome the difficulty of simultaneously reducing emissions of both oxidises of nitrogen (NO x ) and particulate matter from diesel engines. In this paper we present measurements of the performance and NO x and hydrocarbon emissions of a diesel engine operating on a typical diesel oil emulsion and examine through the use of heat release analysis differences found during its combustion relative to standard diesel in the same engine. While producing similar or greater thermal efficiency and improved NO x and hydrocarbon emission outcomes, use of the emulsion also results in an increase in brake specific fuel consumption. Use of the emulsion is also shown to result in a retarded fuel injection, but smaller ignition delay for the same engine timing. As a result of these changes, cylinder pressures and temperatures are lower.

Investigation of the combustion process in an auxiliary heating system using dual‐pump CARS

AbstractA dual‐pump coherent anti‐Stokes Raman spectroscopy (CARS) setup was used for the simultaneous determination of temperature and oxygen/nitrogen ratio in an automotive auxiliary heating system. The auxiliary heating system was equipped with eight windows to provide four line‐of‐sight optical accesses at two different downstream levels. The usable laser pulse energies, which are essentially limited by the damage threshold of the glass windows, were increased by the application of an optical pulse stretcher. Measurements were performed for standard diesel fuel for full‐ and part‐load operation as well as for the model fuel n‐dodecane for full‐load operation. The n‐dodecane measurements can directly be compared with numerical predictions, whereas the results for diesel fuel provide information about the possibility of transfer of the n‐dodecane simulations to real fuel conditions. Copyright © 2006 John Wiley & Sons, Ltd.

A Study on the Performance and Emission Parameters of Hazelnut Oil Methyl Ester as an Alternative Diesel Fuel

In this study, methyl ester which was produced by hazelnut oil has been studied through an experimental method concerning with engine parameters such as torque, power and brake specific fuel consumption and exhaust emissions such as CO, NOx, smoke density and exhaust temperatures. To produce methyl ester, a reactor mechanism was instructed and obtained methyl ester was determined physical and chemical properties in laboratory conditions. Hazelnut oil methyl ester was tested in a four cylinder, turbocharged, direct injection diesel engine. Test results obtained from hazelnut oil methyl ester were compared to standard diesel fuel test results. Engine performance test results showed that the test results of hazelnut oil methyl ester are very close to diesel fuel. CO, NOx, smoke density of hazelnut fuel and exhaust temperatures were lower than of diesel fuel. As a result of this study; it is concluded that hazelnut oil methyl ester could be used as an alternative fuel in diesel engines.

Effect of Cotton Seed Oil Methyl Ester on the Performance and Exhaust Emission of a Diesel Engine

Numerous studies indicated that oil sources in the world will come to an end. As a result, new alternative energy sources will be required to substitute for oil. Some of the experimental studies showed that vegetable oil can be used as alternative fuel in diesel engines. The viscosity of vegetable oil is much higher than that of standard diesel fuel; therefore, the high viscosity of the vegetable oil can cause problems for injection systems and engine components. To decrease viscosity, cottonseed methyl ester was obtained from raw cottonseed oil by transesterification method. In this study, cottonseed methyl ester was used in a four-stroke, single cylinder, and air-cooled diesel engine as alternative fuel. Engine tests carried out at full load-different speed range, the engine torque and power of cottonseed oil methyl ester was found to be lower than that of diesel fuel in the range of 3–9% and specific fuel consumption was higher than that of diesel fuel by approximately 8–10%. CO 2 , CO, and NO x emissions of cottonseed methyl ester were lower than that of diesel fuel.

Alternative Fuel for a Standard Diesel Engine

Alternative fuels have been developed for the commercial diesel products Mk1 and EN590. Appropriate additives were selected from a broad range of oxygenates including alcohols, acetals, ethers, esters, and nitrates by a process of systematic elimination. The resulting fuels called Biodiesel 15 meet all existing standards in force for diesel fuel, are stable, and have similar performance characteristics to standard diesel. Significantly Biodiesel 15 is much cleaner than standard diesel with around 30 per cent or more reductions in particulate matter in the exhaust emissions. Carbon dioxide (CO2) emissions are much lower with Biodiesel 15 than with standard diesel products. Other regulated emissions are on a par with Mk1. The fuel consumption of Biodiesel 15 is 2 per cent lower than that of conventional Mk1.

Primary and Secondary Distillates as Marine Fuel Oil

The component compositions of marine fuel oils satisfying the requirements of TU 38.401-58-302-2001 (ISO 8217) with maximum inclusion of gasoils from destructive refining of crude oil were developed. Light gasoils replace standard diesel fuel in marine fuel oil. The demulsifiability of light and heavy catalytic and coker gasoils and vacuum distillates I and II was evaluated. Its dependence on not only the content of adsorbed resins and aromatic hydrocarbons in the components of the fuel but also and to a greater degree on their ratio in the disperse system was demonstrated. The higher this ratio is, the lower the demulsifiability of the fuel.

The effects of injection timing on NO x emissions of a low heat rejection indirect diesel injection engine

Higher NO x is one of the major problems to be overcomed in a low heat rejection (LHR) diesel engine as insulation leads to an increase in combustion temperature about 200–250 °C compared to an identical standard (STD) diesel engine. High combustion temperatures alter optimum injection timing of a LHR engine. With the proper adjustment of the injection timing, it is possible to partially offset the adverse effect of insulation on heat release rate and hence to obtain improved performance and lower NO x . However, the injection timing and brake specific fuel consumption (BSFC) trade-off must be considered together in performance and NO x emission point of view. In this study, optimum injection timing was found with 4 crank angle (34° CA) retarded before top dead centre (BTDC) in LHR diesel engine in comparison to that of STD diesel engine (38° CA BTDC). When the LHR engine was operated with the injection timing of the 38 crank angle, which is the optimum value of the STD engine, it was shown that NO x emission increased about 15%. However, when the injection timing was retarded to 34° CA in the LHR case, it was observed a decrease on the NO x emissions with about 40% and the brake specific fuel consumption (BSFC) with about 6% compared to that of the STD case. Thus, by retarding the injection timing, an additional 1.5% saving in fuel consumption was obtained.

Heat release model for the combustion of diesel oil emulsions in DI diesel engines

Diagnosing the combustion process in internal combustion engines using cylinder pressure, fuel delivery pressure and injector needle lift data is a well-established and widely used procedure in engine and fuel performance tests. Of the models developed, the first law single zone is the simplest and easiest tool to use for quick preliminary analysis of engine performance. It can yield valuable information about the effect of engine design changes, fuel injection system, fuel type and engine operating conditions on the combustion process and engine performance. The model described in this paper is based on a model designed for both SI and CI engines burning liquid and gaseous hydrocarbon fuels. In its current form, the model can be used for diesel engines burning water/diesel emulsions and allows for the effect of the presence of “inert” water in the combustion products on the ratio of specific heats and heating value of the fuel. The output from the model includes the apparent heat release, fraction of fuel burned, fuel burning rate, heat losses, indicated parameters and average gas temperature. Some results of analysis of the performance of a DI diesel engine burning a standard diesel fuel (referred to in the texts as certified diesel fuel CDF, or simply diesel fuel) and diesel oil emulsion (DOE) are presented.