Automotive Diesel Engine Research Articles

Multi-objective Optimization of Diesel Engine Operating Parameters Under Highway Drive Conditions

Abstract Experimental and optimization work is carried out to study the effects of fuel injection pressure, boost pressure, pilot injection timing, pilot injection quantity and main injection timing as input parameters. A four-cylinder, automotive model direct injection diesel engine, incorporated with a variable-geometry turbocharger, was chosen for the experiment. Engine test runs are conducted at a driving condition of 80.3 Nm torque and an engine speed of 1750 rpm, respectively, corresponding to highway driving conditions, using 10 % of exhaust gases recirculated. The Response Surface Methodology is employed to design experiments and analyze the experimental data to optimize engine parameters, considering the mentioned parameters as input parameters. A multi-objective response approach is adopted to optimize engine-operating parameters to obtain desired performance and engine-out emissions. Confirmatory tests are conducted at design conditions to validate the results predicted by the model. It is observed that for the chosen engine configuration, the optimum performance and emission characteristics could be obtained with 120 kPa boost pressure, 61.1 MPa fuel injection pressure, and 11.5 % of total fuel amount as pilot injection and remaining as main injection quantity at 332° and 359° crank angle, respectively. Overall. fairly better engine performance was observed with the use of selected ranges. It is noted that with the procedures adopted, improved engine performance and a significant reduction in harmful emissions are obtained without using major add-ons. The investigation revealed excellent potential for a diesel engine to be an effective prime mover.

Experimental and numerical analysis of particulate matter deposition in DPF for different blends of Algae Bio diesel

The stringent emission norms have compelled to use Diesel particulate filter (DPF) to reduce particulates emission in automotive Diesel engine. The back pressure developed in the DPF due to the Particulates matter (PM) deposition in porous zone degrades the diesel engine’s performance. So, there is a need of a fuel which should produce less particulates on combustion as well as its produced particulates should be easy to get regenerated inside the DPF. Three different Algae biodiesel blends B20, B40 and B60 were selected for the study, while the results are compared with the diesel fuel. A numerical study has been done with diesel and Algae biodiesel blends to investigate the effect of PM deposition on the DPF performance. The results of PM concentration and the pressure drop has been predicted for t = 2000s. and compared with the results predicted for diesel fuel. The summarized velocity contours and the PM concentration plots show that a maximum of the PM concentration was found in the diesel fuel case, while the lower found in B60 algae blend. Also, the pressure drop was found to increase with the increase in PM deposition in each case of fuel. The SEM-EDS analysis is done after collecting PM samples after combustion shows a higher percentage of Oxygen and lower Carbon with an increment of Biodiesel in the blend. This work provides a brief idea about the PM deposition in DPF while using Diesel and Algae Biodiesel blends and highlighting the better fuel option for Diesel Engine.

Investigations on the effects of injection parameters and EGR in a glow plug assisted methanol fueled Hot Surface Ignition (HSI) Engine

Methanol can be produced from renewable sources and is also clean burning. Hence it is an ideal alternative fuel for transportation applications. However, its low cetane number prevents its direct application in compression ignition (CI) engines. One of the promising but not widely explored methods is to use a hot surface for its ignition in CI engines at normal compression ratios. In this work a turbocharged automotive common rail diesel engine was modified to operate in the hot surface ignition (HSI) mode with methanol as the sole fuel with 3% by mass of lubricity and corrosion inhibiting additive. Initially, a single pulse injection (SPI) strategy was employed at different injection timings at a BMEP of 8 bar. Subsequently a double pulse injection (DPI) strategy was employed and the effects of gap between the injection pulses, injection timing and injection pulse width share among the two pulses were studied. The HSI mode of neat methanol performed with comparable brake thermal efficiency (BTE), reduced combustion rates and hence low NOx emission levels with respect to diesel operation when the DPI mode was employed with almost equal pulse width share. Engine performance was better at rail pressures of around 800 bar. Hot EGR of up to 8% was beneficial as it reduced the engine-out NOx without affecting the BTE. The engine was operated at different BMEPs in the range of 4–10 bar and compared with the baseline diesel operation. The BTE was similar to the baseline diesel engine at all loads. Engine-out NOx was lower than diesel operation by 23.6%–61.5% while near zero smoke levels and similar CO and THC emissions (after the DOC) were observed. Though slipped methanol and formaldehyde were the significant unregulated emissions, they were reduced to very low levels after the DOC.

Effect of pilot fuel quantity and fuel injection pressure on combustion, performance and emission characteristics of an automotive diesel engine

The work presented here experimentally investigates the effect of pilot quantity (PQ) on combustion, performance and emission characteristics of an automotive diesel engine. All the experiments were performed at max torque speed of the test engine (1600 rpm) and 75 % of full engine load. Three PQs under consideration are 10 %, 20 % and 30 % of total fuel mass per cycle while maintaining the fixed pilot as well as main injection timings. The minimum PQ (10 %) considered in the study was found sufficient to enhance the in-cylinder thermodynamic conditions before main injection starts. Also, fuel injection pressure (FIP) was maintained constant at 500 bar initially. Obtained results showed that the pilot injection mode with 30 % PQ reduced nitrogen oxide (NO) emission as well as brake specific fuel consumption (BSFC) by 21.87 % and 1.46 % respectively compared to reference single injection mode while smoke emissions were increased by 77.64 %. In order to curb this negative effect of higher smoke emissions offered by pilot injection, FIP was increased from 500 bar to 700 bar and similar experiments were repeated. The experimental results demonstrated that higher FIP significantly reduced smoke emissions as well as fuel consumption under all the considered pilot injection modes with acceptable rise of NO emission which was still considerably lower than reference single injection mode. For e.g., when FIP was increased from 500 bar to 700 bar in case of pilot injection mode with 30 % PQ, smoke emissions and BSFC were reduced by 26.40 % and 2.14 % respectively, while NO emission was increased by 6.30 %. Therefore, it can be said that combination of pilot injection and high FIP leads to overall improvement in performance and emission characteristics of the test engine.

Combustion Optimization of a Premixed Ultra-Lean Blend of Natural Gas and Hydrogen in a Dual Fuel Engine Running at Low Load

<div>The numerical study presented in this article is based on an automotive diesel engine (2.8 L, 4-cylinder, turbocharged), considering a NG–H<sub>2</sub> blend with 30 vol% of H<sub>2</sub>, ignited by multiple diesel fuel injections. The 3D-CFD investigation aims at improving BTE, CO, and UHC emissions at low load, by means of an optimization of the diesel fuel injection strategy and of the in-cylinder turbulence (swirl ratio, SR). The operating condition is 3000 rpm – BMEP = 2 bar, corresponding to about 25% of the maximum load of a gen-set engine, able to deliver up to 83 kW at 3000 rpm (rated speed). The reference diesel fuel injection strategy, adopted in all the previous numerical and experimental studies, is a three-shot mode. The numerical optimization carried out in this study consisted in finding the optimal number of injections per cycle, as well as the best timing of each injection and the fuel mass split among the injections. The analysis revealed that combustion can be improved by increasing the local concentration of the more reactive fuel (diesel): in detail, the best strategy is a two-shot mode, with SOI1 = −35°CA AFTDC and SOI2 = −20°CA AFTDC, injecting 70% of the total diesel fuel mass at the first shot. As far as the SR is concerned, the best compromise between performance and emissions was found for a relatively low SR = 1.4. The optimization permitted to extract the full potential of the H<sub>2</sub> enrichment in the DF H<sub>2</sub>/NG–diesel combustion also at low loads: in comparison to the DF NG case, combustion efficiency, and gross indicated thermal efficiency have been improved by 45.7% and 61.0%, respectively; CO- and UHC-specific emissions have been reduced by about 85.0%. Comparing CDC to the optimized DF 30 vol% H<sub>2</sub>/NG–diesel case, soot emissions are completely canceled, CO<sub>2</sub>-specific emissions have been reduced by approximately 42.0%, NO<sub>x</sub>-specific emissions by 33.8%. However, further work has to be done in order to reach comparable values of HC and CO, which are still higher than in a standard diesel combustion.</div>

Study of the process of connecting rod liners’ shape changing in the pre-failure operation period of transport and technological machines and equipment

BACKGROUND: During the operation of transport and technological machines and equipment, the most frequent failure is loose running of connecting rod liners of a crankshaft. Previous studies on tractor, locomotive and automotive diesel engines did not sufficiently disclose the reasons for loose running of liners. AIMS: Study of the stress-strain state of the steel base of connecting rod liners as the initial and developing factors of the process leading to failure. METHODS: The research is based on the analysis of numerous works devoted to the study of the causes of loose running of connecting rod liners of various internal combustion engines. The methods and results on the operational and bench studies of the stress state and shape changing of connecting rod liners for the KAMAZ-740 (8Ch 12/12) engine obtained by the team of authors are used as the basic data. RESULTS: The process of change in stress state and consequent change in geometric parameters of the steel base, accompanied by change in the shape of connecting rod liners of the KAMAZ-740 engines has been revealed. It is established with the study that the occurrence of failure is not sudden. The process proceeds according to a certain pattern in three stages. The first stage is characterized by the appearance of deformation of a liner due to excessive stress state; the second stage is caused by development of obtained deformations up to critical values; the third stage is loose running of a connecting rod due to obtained deformations and violations of liner’s hydrodynamics conditions. The main result is justification of requirements and conditions for ensuring stability of parameters and shape of liners during long-term operation of engine. CONCLUSIONS: Knowledge of the process leading to the change in shape of crankshaft bearing liners makes it possible to develop design and technological solutions and recommendations to eliminate failures by optimizing the parameters of liners.

EXPERIMENTAL INVESTIGATION OF THE EFFECTS OF WATER ADDITION INTO THE INTAKE AIR ON COMBUSTION PARAMETERS, ENERGY BALANCE AND DEVELOPING AN EMPIRICAL COMBUSTION DURATION RELATION IN AUTOMOBILE DIESEL ENGINE

The effect of the water addition into the intake air (WAIA) on cylinder pressure, temperature, heat release rate (HRR), combustion duration (CD), and energy balance in an automotive diesel engine have been investigated experimentally. Also, an empirical correlation has been developed for estimating CD using the HRR. This relation has been developed by applying the multiple curve fitting method, taking into account experimental results for different water ratios such as (2, 4, 6, 8, and 10) %, different engine loads, and different engine speeds such as (2000, 2500, 3000, 3500, and 4000) rpms. The test results showed that cylinder pressure values generally increased at (2000, 2500, and 3500) rpm, but they decreased at (3000 and 4000) rpm for all of the selected water ratios. Also, maximum cylinder temperature values have occurred at crank angles farther from TDC for WAIA. Cylinder temperature values mostly decreased at (2000, 2500, and 3000) rpms, but they generally increased at (3500 and 4000) rpms for WAIA. Also, maximum cylinder temperature values were occurred at crank angles farther from TDC for WAIA. HRR values generally decreased at (2000, 2500, 3500, and 4000) rpms, but they generally increased at 3000 rpm. It has been determined that the CDs were generally shortened at all of the engine speeds under full loads with water addition. CD values for NDF and (2.42, 4.22, 5.95, 8.32, 9.46) % water ratios have been determined as (13.10, 12.96, 12.93, 12.68, 12.95, and 13.576) °CA, respectively, at 2000 rpm. The effective power values according to the chemical energy of the fuel generally decrease with WAIA at 2000 rpm. However, the effective power values according to the chemical energy of the fuel increase for high WRs at 4000 rpm.

An Analytical Study of the Elements of Airworthiness Certification Technology Based on the Development of the Conversion of Diesel Engines for Vehicles to Aviation

Aircraft reciprocating engines have been in operation over the past 100 years, which is a testament to their high levels of reliability and stability. Compared to turbine engines, reciprocating engines are at a disadvantage when it comes to high-speed flight. Nevertheless, they are widely used mainly for small aircraft thanks to their high specific power or power-to-weight ratio. Considering that propulsion systems account for approximately 40% of the aircraft price, lightness and high performance are key attributes of aircraft to achieve longer endurance. With the advantages offered by diesel engines, such as fuel economy, less maintenance, and a long lifespan, many attempts have been made to mount automotive diesel engines on urban air mobility and light aircraft. Recognizing advanced automotive diesel technology, where the power-to-weight ratio of the diesel engine is approximately 1 PS/kg, we analyzed a case where an automobile engine was converted for use in an aircraft. We focused on the Mercedes-Benz OM640 and the Austro AE300 and disassembled the two engines for comparative analysis. We then classified the engine components modified for aircraft use by (1) defining the major engine parts as fixed and alteration ones; (2) identifying the airworthiness-related alteration parts; and (3) categorizing the conversion purposes into classes A, B, and C. Components under class A were further categorized into subgroups in accordance with the airworthiness certification specifications outlined by the European Union Aviation Safety Agency. This helped determine the corresponding airworthiness standards for each subgroup. An inspection of the oil supply system revealed the need to apply safety wiring for some components to prevent possible oil leakages, which can be caused by the pressure difference with increasing altitude. Moreover, given that sensor manufacturers are required to present guidelines for sensor redundancy through numerous designs and tests and secure single-fault tolerance, we established criteria for selecting and applying sensors and separating sensors that must be made redundant from ones that are not subject to sensor redundancy.

A Review on Sustainable Approach for Production of Biodiesel from Waste Cooking Oil: A Case Study of Brunei Darussalam

Biofuels like biodiesel and bioethanol are the latest technologies to meet the rising energy demand and to replace depleting petroleum supplies. Biodiesel, which is made from vegetable oils, can be used to replace diesel fuel. Vegetable oils are a sustainable energy resource with a similar energy content to diesel fuel. In the proposed process, the main product from the reaction is biodiesel, whereas the by-products consist of glycerol and fertilizer. Biodiesel is mainly used in automotive diesel engines for various reasons, such as having a greater oxygen content, a higher cetane number, a higher viscosity, a lower aromatic content, and very little sulfur. These properties are essential in engine performance, combustion, and emissions. This review provides a comprehensive analysis of recent literature on biodiesel production methods from waste cooking oil, where the methods are grouped systematically and assessed. A decision table on process selection is provided to screen the most suitable technology for biodiesel production from waste cooking oil. The properties and application of potential products and by-products are also discussed. Finally, the case study of supplying biodiesel for B5 fuel in Brunei Darussalam is also provided.

An innovative method of ammonia use in a light-duty automotive diesel engine to enhance diesel combustion, performance, and emissions

This study investigated the novel method of ammonia use in a light-duty automotive diesel engine. An emulsification technique and ammonia solution are combined and adopted to prepare ammonia solution in diesel emulsion referred to as emulsified diesel-ammonia solution (EDAS) and tested under similar diesel combustion conditions. The ammonia solution concentration in EDAS was fixed as 10% by volume (EDAS10) with 2% v/v of surfactant to avoid excessive ammonia slip, corrosive effects, and oxides of nitrogen (NOx) formation. The aim of this study is to explore the effect of presence of hydrogen in EDAS10 on the diesel combustion process under high-pressure multiple injection strategies. Experiments were performed at low, medium, and high loads at the same combustion phasing (CA50) and total energy input as that of diesel to investigate the influence of EDAS10 on combustion, performance, and emissions. The start of injection of EDAS10 and exhaust gas recirculation rate was varied to attain the CA50. The combustion results showed that the EDAS10 blend had increased the heat release rate in the premixed combustion phase with shortened duration and decreased the heat release rate in the diffusion combustion phase compared to neat diesel operation. Double and triple injection of EDAS10 blend also increased the indicated and brake thermal efficiencies by about 4–7% than neat diesel operation. A decrease in 50–67% unburnt emissions, 8–13% decrease in smoke, and 7–19% increase in NO emissions, 2–10% increase in CO2emissions were observed with EDAS10 when compared to diesel operation.

Experimental probe into an automative engine run on waste cooking oil biodiesel blend at varying engine speeds

The present work attempts to evaluate the performance of an automotive diesel engine run on waste cooking oil biodiesel (WCO) blend at variable engine speeds. The composition of the blend (B40) used in the study is 40% WCO and 60% diesel by volume and the engine used for the experimentation is a naturally aspirated, water-cooled and direct injection type having a compression ratio of 18:1. The engine settings used in the study are an injection timing (IT) of 150bTDC and a fuel injection pressure (IP) of 500 bar. The performance and emissions characteristics of the automotive engine are studied at various loads of 20%, 40%, 60%, 80% and 100% and at different engine speeds of 1500, 1800 and 2400 rpm. The first two rotational speeds are chosen to study the stationary power generation capabilities of the blend, while the feasibility of blend for automotive applications has been evaluated at 2400 rpm. Experiments have also been conducted on the engine run on mineral diesel fuel in order to make a comparative analysis. At full load, the maximum brake thermal efficiency (BTE) is found to be 21.51%, 25.48% and 23.56% for the blend at 1500, 1800 and 2400 rpm, respectively. At 2400 rpm and at 20% and 40% loads, the blend shows an absolute improvement in BTE of 0.17% and 0.03%, respectively over diesel fuel. On an average, there is a decrease of carbon monoxide (CO) emissions by 87.5%, 22.22% and 14.28% at 1500, 1800 and 2400 rpm as compared to diesel fuel. At 1500 and 2400 rpm, there is an average absolute increase in hydrocarbon (HC) emissions by 1.6 ppm and 9.6 ppm, respectively; while at 1800 rpm, an average decrease in HC emissions by 4 ppm is observed vis-a-vis diesel fuel. While emissions of oxides of nitrogen (NOx) as compared to diesel fuel increased on an average by 19.43%, 26.09% and 1.01% at 1500, 1800 and 2400 rpm, respectively.

Ways to improve the efficiency of operation of automotive diesel engines at low temperatures

The choice and observance of the correct operating conditions in these conditions will significantly reduce the consumption of fuel and lubricants, increase the life of engines and improve the working conditions of service personnel. The paper highlights the main directions for improving the operational characteristics of diesel engines associated with ensuring a guaranteed start-up process, reducing the preparation time for the acceptance of the pre-start load and ensuring optimal thermal conditions during engine operation. The justification of the need for the use of pre-start thermal preparation of diesel engines is given. As such, it is proposed to use a thermal accumulator as an energy-efficient and energy-saving equipment.

Evaluation of the technical condition of locomotives using modern methods and tools

Considering its real technical condition when planning the volume of repair of locomotive equipment is one of the most important bases for reducing the costs of using railways and the cost of transportation. Continuous monitoring of the technical condition of the locomotive in use is carried out using stationary and on-board technical diagnostic tools. The method of small deviations is now widely used in various fields of science. It is a method designed to determine the existence of a correlation between the changes in parameters describing a process or a physical phenomenon. The method is based on the fact that some of the parameters of the process, in their not so large deviations from their initial values, the relationship between these deviations can be adequately expressed using certain differential calculus ratios. The wide-band exhaust gases oxygen content sensor can continuously monitor the air excess coefficient in the locomotive diesel engine cylinders. This type of sensor is widely used in automotive diesel engine control systems. It means the indirect estimation of the engine cylinders mixture quality by the exhaust gases' oxygen content

Reduction of vibration and noise pollution from agricultural tractor engine using novel pine oil and soapnut oil methyl ester as fuel.

The exhaust emissions from automotive diesel engines are successfully controlled over the years by adopting different combustion strategies and after treatment devices, whereas the combustion induced vibration and noise are the major pollutant in off-road vehicle engines and yet to be optimized. In the present study, a twin cylinder, Simpson's S-217 tractor diesel engine was used to evaluate the performance, combustion, vibration, and noise characteristics, using biofuel blends. For this study, the blends of pine oil - soapnut oil biodiesel (P75SNB25), diesel - soapnut oil biodiesel (SNB20) and diesel were used as fuel. The pine oil used in this research was purchased and used in its neat form. The soapnut oil was extracted from the soapnut seeds by cold pressing method and trans-esterified in two stages by using methanol and catalysts. The experimental results revealed that the performance and combustion characteristics of the blend P75SNB25 was superior to diesel and the blend SNB20 was slightly inferior to diesel. For the blend P75SNB25, the amplitude of acceleration with respect to time was reduced by 19.48% and 11.58% at no load and full load conditions respectively, whereas for the blend SNB20, the amplitude of acceleration showed a reduction of 14.27% and 9.46% at no load and full load conditions respectively in comparison with diesel operation. But both the blends P75SNB25 and SNB20 showed a maximum reduction of noise by 2.34% at different engine loads compared to diesel operation.

Insights of Selective Catalytic Reduction Technology for Nitrogen Oxides Control in Marine Engine Applications

The international shipping industry is facing increasingly stringent limitations on nitrogen oxide (NOx) emissions. New solutions for reducing NOx emitted by marine engines need to be investigated to find the best technology. Selective Catalytic Reduction (SCR) is an advanced active emissions control technology successfully used in automotive diesel engines; it could be applied to marine engines with ad-hoc solutions to integrate it in the exhaust of large engines. In this study, a commercial SCR was tested at the exhaust of a diesel engine in inlet gas conditions typical of a marine engine. The SCR system consisted of a custom monolith (provided by Hug-Engineering AG) that enabled seamless integration for a broad range of engine sizes; the active phases were V2O5 (3 wt%)-WO3 (7 wt%)-TiO2 (75 wt%). The monolith was studied at the laboratory scale for its in-depth chemical/physical characterization and by means of an intermediate-scale engine, reproducing the exhaust gas conditions of a full-scale marine engine. The system’s effectiveness in terms of NOx removal for the selected engine operating conditions was evaluated in a wide range of temperature and NOx emissions values and for different quantities of the reduction agent (AdBlue or ammonia) added to exhaust gases. The investigated technological solution resulted in efficient NOx emission control from a marine engine.

Experimental study on combustion of an automotive diesel engine fuelled with CNG

Presenting the influence of compressed natural gas (CNG) used as alternative fuel on the combustion of an automotive diesel engine represents the main objective of this paper. The paper studies brake specific energetic consumption, in-cylinder pressure and pressure rise rate, carbon dioxide, nitrogen oxides, smoke and hydrocarbons emissions at 2000 rev/min and at 40%, 55% and 70% load. Low carbon content of the alternative fuel will determine lower CO2 at all loads; NOx and smoke emissions are influenced by both energetic substitution and engine operating regime. HC emission will reach higher levels in diesel-gas mode than in conventional mode as the homogeneous percentage of the charge per cycle grows with the quantity of CNG admitted into the cylinder. In all cases in-cylinder pressure and pressure rise rate are higher in dual-fuel mode than those in conventional operating mode due to higher quantity of premixed charge developed during the ignition delay phase. The higher LHV (lower heating value) and the gaseous state of CNG will determine at all loads lower brake specific energetic consumption. Smoke emission will be negatively influenced in low to medium loads but in high loads it will drop by more than 30 percent.

Ways to improve the efficiency of operation of automotive diesel engines at low temperatures

The choice and observance of the correct operating conditions in these conditions will significantly reduce the consumption of fuel and lubricants, increase the life of engines and improve the working conditions of service personnel. The paper highlights the main directions for improving the operational characteristics of diesel engines associated with ensuring a guaranteed start-up process, reducing the preparation time for the acceptance of the pre-start load and ensuring optimal thermal conditions during engine operation. The justification of the need for the use of pre-start thermal preparation of diesel engines is given. As such, it is proposed to use a thermal accumulator as an energy-efficient and energy-saving equipment.

A supervised machine learning model for determining lubricant oil operating conditions

AbstractMachine learning tools for analysing lubricating oil data have enabled better information in the condition based maintenance (CBM) approach to the process of diagnosing and predicting failures in diesel‐powered vehicle fleets. With the increase in the number of sensors inserted in vehicles, it is possible for companies to stockpile large quantities of information in real time. As such, the development of data‐driven tools will enable accurate identification of the level of wear of a system, evolving CBM into a more reliable and dynamic approach. Following this type of data‐based analysis focusing on determining the wear of systems and equipment, this paper presents an intelligent system for assessing the condition of lubricating oil in automotive diesel engines. To this end, we analyse the use of raw data obtained from the sensors installed in the car and evaluate in conjunction with the insertion of engineered features designed the best way to determine the operating state of the oils. The results presented in this analysis show that to explain 90% of the variation in the original data only the variables kinematic viscosity, dynamic viscosity, engine oil temperature and OSF_v3 are needed. After evaluating the quality of the variables, we conducted an experimental study to analyse the performance of various machine learning algorithms, taking into account the number of features as input data. The results show that the proposed system has the ability to identify the operating conditions of lubricating oil using seven variables as input to a model based on gradient boosting, obtaining a recall result of 93%, precision of 96% and F1‐score of 94%. We conducted a set of additional studies to understand how different subsets of variables affected the performance of the models, and the results show that the best combination includes information regarding the engine speed, coolant and oil temperature, oil pressure, the oil stress factor (OSF_v3), kinematic viscosity, and the dynamic viscosity.

Investigation of the combustion process of activated fuel in an automotive diesel engine

BACKGROUND: Intensive development of the transport sphere and the extension of the fleet of tractors and cars, as well as the tightening of standards and requirements in the field of exhaust gas emissions have resulted in increased requirements for the combustion process. This problem can be solved by improving the working process in the engine by preheating the fuel to 300 C in the high pressure fuel supply system. Under external thermal influence, the conditions of mixture formation are improved, an increase in the rate of preflame reactions and a positive change in the dynamics of the combustion process are observed. When potential energy of hydrocarbon molecules increases in the activated complex system, energy is redistributed among active molecules. Along with this, the rate coefficient of a chemical reaction increases due to the concentration of foci of hydrocarbon molecules that have reached the energy barrier.
 The object of research is the process of diesel fuel combustion at preliminary external influence on it.
 AIMS: The aim is to study the combustion process of a motor-tractor diesel engine upon fuel activation. Development of a scheme of individual phases of the activated diesel fuel combustion of depending on the temperature at heating.
 METHODS: Theoretical study and analysis of the combustion process of thermally preprepared fuel for an automotive diesel engine. Theoretical determination of the dependence of the rate of formation and concentration of toxic components and dispersed particles on the rate constant of direct and reverse chemical reactions, as well as on the activation temperature of fuel at emission in exhaust gases.
 RESULTS: The actual coefficient of molecular change of the working mixture increases when diesel fuel is activated. The rate of formation of total nitrogen oxides and hydrocarbons increases by 1.79% and 3.66%. The proportion of unburned carbon in the combustion process on activated fuel varies within (24) %.
 CONCLUSIONS: Theoretically, a scheme for changing individual phases of the activated fuel combustion process by time and temperature has been developed. Fuel heating accelerates the pre-flame preparation in the liquid phase, shortens the duration of the rapid gorenje phase. The concentration of toxic indicators depends on the constant of the chemical reaction rate and the activation temperature of the fuel.

Biological toxicity risk assessment of two potential neutral carbon diesel fuel substitutes

We investigated the biological response of soluble organic fraction (SOF) and water-soluble fraction (WSF) extracted from particulate matter (PM) emitted by an automotive diesel engine operating in a representative urban driving condition. The engine was fueled with ultra-low sulfur diesel (ULSD), and its binary blends by volume with 13% of butanol (Bu13), and with hydrotreated vegetable oil (HVO) at 13% (HVO13) and 20% (HVO20). Cytotoxicity, genotoxicity, oxidative DNA damage and ecotoxicity tests were carried out, and 16 polycyclic aromatic hydrocarbons (PAH) expressed as tbenzo(a)pyrene total toxicity equivalent (BaP-TEQ) were also analyzed. The Hepatocarcinoma epithelial cell line (HepG2) was exposed to SOF for 24 h and analyzed using comet assay, with the inclusion of formamidopyrimidine DNA glycosylase (FPG) and endonuclease III (Endo III) to recognize oxidized DNA bases. The WSF was evaluated through acute ecotoxicity tests with the aquatic microcrustacean Daphnia pulex (D. Pulex). Results showed that there was no cytotoxic activity for all tested SOF concentrations. Genotoxic responses by all the SOF samples were at same level, except for the HVO13 which was weaker in the absence of the enzymes. The addition of the FPG and Endo III enzymes resulted in a significant increase in the comet tail, indicating that the DNA damage from SOF for all tested fuel blends involves oxidative damage including a higher level of oxidized purines for ULSD and Bu13 in comparison with HVO blends, but the oxidized pyrimidines for HVO blends were slightly higher compared to Bu13. The WSF did not show acute ecotoxicity for any of the fuels. Unlike other samples, Bu13-derived particles significantly increase the BaP-TEQ. The contribution to the genotoxic activity and oxidative DNA from SOF was not correlated to BaP-TEQ, which means that the biological activity of PM might be affected also by other toxic compounds present in particulate phase.