Truck Diesel Engine Research Articles

Failure analysis of a truck diesel engine injector nozzle-valve

The longitudinal cracking took place on the head of an injector nozzle-valve used truck diesel engine during the engine trial test. The fatigue fracture is the dominant failure mechanism of the nozzle-valve. A lot of ovoid and elongated dents were found on the cone of internal cavity of nozzle-valve and the dents were associated to debonding of the ovoid compound inclusions composed of calcium aluminate and MnS, and MnS stringers on the surface from the matrix. Debonding of inclusions was most likely to occur in the process of the carburization-heating of the nozzle-valve. Due to non-coherence between the inclusions and the matrix, debonding of inclusions maybe took place during the process of operating under the action of alternative operational load on the nozzle-valve cone. The size of these dents was enlarged further owing to the cavitation damage during the operating. The crack origin was just initiated from a large ovoid dent appearing at the seal interface between the nozzle-valve cone and the needle-valve, which acted as stress raiser. The edge of the large ovoid dent at the specific location was subjected to two kinds of stresses in the operating, the circumferential tensile stress resulting from the internal pressure of fuel-oil and the circumferential tensile stress resulting from the contact load between the nozzle-valve cone and the needle-valve. Under the action of the alternative superimposing stress, the fatigue crack initiated from the edge of the large dent and propagated outward along the radial to lead to longitudinal cracking throughout the entire wall thickness of nozzle-valve. The upper cone of nozzle-valve had been almost carburized throughout, which would strongly embrittle the cone with thin wall thickness to promote crack propagation.

The science and technology of using nano-materials in engine oil as a lubricant additives

New additives are under development to improve wear and tear properties of engine components, fuel efficiency and to reduce carbon emissions from cars and commercial vehicles by reducing friction. To prolong the lifetime and maintain the efficiency of exhaust car emission reduction devices, the modern engine oils must contain low sulphate dash, phosphorus and sulfur. This thesis describes the impact of adding lubricant additives on the visco-elastic and thermo-physical properties of engine oils. The engine oils used in automotive industry are one of the most widely used consumable entities. There has been an ever increasing demand to improve the performance of engine oil lubricants. For that purpose, performance enhancing additives have been added to engine oil lubricants since past few decades. Subsequently, there is an ever increasing need to show the contribution lubricant additives make towards the automotive industry, the consumer and the impact on the environment. Such additives encompass applications for lubrication of passenger car (diesel and gasoline engine) lubricants, truck, coach and bus diesel engine lubricants, heavy duty engine oil etc. The document demonstrates the contribution made by lubricant additives in these applications to the consumer, industry and the environment, through their ability to optimise desirable lubricant properties while suppressing unwanted ones.

The challenges and benefits of using carbon nano-tubes as friction modifier lubricant additives

The engine oils used in automotive industry are one of the most widely used consumable entities. There has been an ever increasing demand to improve the performance of engine oil lubricants. For that purpose, performance enhancing additives have been added to engine oil lubricants since past few decades. Subsequently, there is an ever increasing need to show the contribution lubricant additives make towards the automotive industry, the consumer and the impact on the environment. Such additives encompass applications for lubrication of passenger car (diesel and gasoline engine) lubricants, truck, coach and bus diesel engine lubricants, heavy duty engine oil etc. The document demonstrates the contribution made by lubricant additives in these applications to the consumer, industry and the environment, through their ability to optimise desirable lubricant properties while suppressing unwanted ones. New additives are under development to improve wear and tear properties of engine components, fuel efficiency and to reduce carbon emissions from cars and commercial vehicles by reducing friction. To prolong the lifetime and maintain the efficiency of exhaust car emission reduction devices, the modern engine oils must contain low sulphated ash, phosphorus and sulfur. This thesis describes the impact of adding lubricant additives on the visco-elastic and thermo-physical properties of engine oils. In this paper the benefits and challenges of Carbon Nanotubes as Lubricant additives has been discussed in detail.

Effect of extra-large compound calcium-aluminosilicate inclusions on cracking of camshafts

About one-hundred out of three-hundred camshafts were found to crack in varying degrees after finishing final heat treatment of induction-quenching. The cracked camshafts were made from one steel ingot of same furnace number. The failed camshafts are used in truck diesel engine with six cylinders. Stereomicroscope observation showed that several longitudinal and radial cracks were presented on the external surfaces of journals and cams and the side of journals of camshafts. Numerous extra-large elongated compound inclusions of calcium-aluminosilicate (CaO⋅Al2O3⋅SiO2) along the longitudinal of camshaft were found on the fracture surfaces. Fracture surfaces characteristically “woody” in appearance or lamellar and deep groove fracture topography were confirmed to be associated with inclusion distribution along the longitudinal direction of camshaft. Metallographic examination indicated that the camshaft material had a very low purity, especially in the surface region of camshafts, i.e. crack origin regions. The total index of oxide inclusion of the metallographic samples from the smoothed fracture surfaces was evaluated to be K4 = 181 according to DIN standard, much higher than the specified index, K4 ≤ 30. During induction-quenching process, a hoop tensile thermal stress and a hoop tensile transformation stress would develop on the matrix surrounding the compound inclusion of calcium-aluminosilicate due to the significant difference in the thermal expansion coefficients between them and the volume expansion of matrix in the surface region resulting from the transformation of austenite to martensite. When the superimposed stress of both stresses was greater than the tensile strength of matrix material in the surface region, the micro-cracks along the radial of compound inclusion would develop on the matrix surrounding the compound inclusion to lead to cracking of camshaft.

Design of a Sequential Axial Turbocharger for Automotive Application

In the last few years, the perspective of climate change, energy, competitiveness, and fuel consumption in the transportation sector has become one of the most significant public policy issues of our time. As different methods are being adapted into light-duty vehicles like engine downsizing, on the other hand, the increase in carbon emissions of heavy-duty trucks is becoming a major concern. Although previous researches have studied the methodology for selecting optimized turbocharger performance, still further investigation is needed to create a method for achieving the highest performance for a sequential axial turbocharger. Therefore, in this study, the design of a two-stage turbocharger system that consists of a radial turbine connected in series to an axial turbine is considered. The specific two-stage turbine was designed specifically and will be tested on a MAN 6.9 L diesel truck engine. With the engine already equipped with a radial type turbine, the newly designed two-stage turbine will be adapted to the engine to give more efficiency and power to it. Firstly, the modelling and simulation of the engine were done in Gt-Power, to achieve the same power and torque curves presented in the MAN engine specification sheet. Once that was achieved, the second task was to design and optimise a radial and axial turbine, which will form part of a two-stage system, through Computational Fluid Dynamics (CFD) analysis. Necessary data were gathered from the engine’s output conditions, for the ability to design the new turbo system. Lastly, the new turbine data were entered into the new two-stage turbo GT-Power model, and a comparison of the results was made. The CFD analysis, executed in ANSYS, for the radial turbine gave an 83.4% efficiency at 85,000 rpm, and for the axial turbine, the efficiency achieved was 81.74% at 78,500 rpm.

Abstract 597: Occupational exposure to diesel engine exhaust and alternations in serum microRNAs

Abstract Diesel engine exhaust (DEE) is a known lung carcinogen and may be associated with other tumors, however, the mechanisms of action by which DEE causes cancer is not well understood. MicroRNAs (miRNAs), which are small non-coding RNA molecules that play a role in post-transcriptional regulation of gene expression, are altered in multiple tumors and have been observed to be differentially expressed in a variety of biospecimen types in smokers as well as in relation to short-term air pollution exposure. To evaluate whether serum levels of miRNAs are altered in healthy workers occupationally exposed to DEE, we analyzed samples collected in a cross-sectional molecular epidemiology study of diesel engine truck testing facility workers and comparable unexposed controls in China. A panel of 44 miRNAs were measured in 46 workers exposed to relatively high air levels of DEE and 45 controls using the Fireplex circulating miRNA assay (Abcam, Inc.), which profiles miRNAs directly from biofluids. The exposure-response relationship between categorical EC levels and each miRNA was analyzed by linear regression adjusted for age, body mass index, smoking status, current alcohol use and recent infection. We identified two miRNAs that showed a monotonic inverse exposure-response association with DEE: miR-191-5p and miR-93-5p. Levels of miR-191-5p in arbitrary units (A.U.) of fluorescence were 400.7, 333.0, 322.6, and 260.0 in controls and across increasing tertiles of EC, respectively (p for trend = 0.001, FDR = 0.05). Levels of miR-93-5p were 747.1, 713.7, 720.5, and 625.4 A.U. in controls and increasing tertiles of EC, respectively (p for trend = 0.008, FDR = 0.18). Both miRNAs have been reported to influence several biological processes important in carcinogenesis. Our results suggest that occupational exposure to DEE may affect circulating miRNAs in healthy workers. Citation Format: Wei Hu, Bryan A. Bassig, Yufei Dai, Dianzhi Ren, Huawei Duan, Yong Niu, Jun Xu, Wei Fu, Kees Meliefste, Baosen Zhou, Jufang Yang, Meng Ye, Xiaowei Jia, Tao Meng, Ping Bin, Jason YY Wong, Dean H. Hosgood, Nathaniel Rothman, Roel C. Vermeulen, Debra T. Silverman, Yuxin Zheng, Qing Lan. Occupational exposure to diesel engine exhaust and alternations in serum microRNAs [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 597.

Potential of carbon dioxide transcritical power cycle waste-heat recovery systems for heavy-duty truck engines

Carbon dioxide transcritical power cycle (CTPC) systems are considered a new and particularly interesting technology for waste-heat recovery. In heavy-duty truck engine applications, challenges arise from the highly transient nature of the available heat sources. This paper presents an integrated model of CTPC systems recovering heat from a truck diesel engine, developed in GT-SUITE software and calibrated against experimental data, considers the likely fuel consumption improvements and identifies directions for further improvement. The transient performance of four different CTPC systems is predicted over a heavy-heavy duty driving cycle with a control structure comprising a mode switch module and two PID controllers implemented to realize stable, safe and optimal operation. Three operating modes are defined: startup mode, power mode, and stop mode. The results demonstrate that CTPC systems are robust and able to operate safely even when the heat sources are highly transient, indicating a promising potential for the deployment of this technology in such applications. Furthermore, a system layout with both a preheater and a recuperator appears as the most promising, allowing a 2.3% improvement in brake thermal efficiency over the whole driving cycle by utilizing 48.9% of the exhaust and 72.8% of the coolant energy, even when the pump and turbine efficiencies are as low as 50%. Finally, factor analysis suggests that important directions aimed at improving the performance and facilitating CTPC system integration with vehicle engines are: (1) ensuring long-duration operation in power mode, e.g., by employment in long-haul trucks; and (2) enhancing pump and turbine performance.

Results of simulation and experimental research of automobile gas diesel engine

The paper is dedicated to conversion of a truck diesel engine into a gas diesel engine. Different ways of diesel engine conversion for operation on natural gas were analyzed. The gas diesel working process with minimized portion of igniting diesel fuel supplied by the Common Rail system was selected as the most suitable for such an engine. Modular gas feed and electronic engine control systems were developed in MADI which may be mounted on high- and medium-speed gas diesel engines. The fuel supply system of the base diesel engine was preserved though a new algorithm of fuel injection for the gas diesel engine was developed. The systems were perfected using simulation by computer model developed in MADI and during engine tests. The gas diesel engine demonstrated good fuel efficiency and considerable decrease of NOx and CO2 emissions, though its power at low speed decreased compared to the base diesel engine. The ways to improve this drawback during the future work were proposed.

Optimization of an organic Rankine cycle constrained by the application of compact heat exchangers

Recovering waste heat from the exhaust gases of heavy-duty diesel truck engines by using the organic Rankine cycle can reduce both fuel consumption and greenhouse gas emissions. The design of such systems is constrained by the space available for installation; thus, an optimization procedure is required. In this research work, a two-objective optimization, based on the maximization of power output and minimization of the total heat exchanger surface area, is implemented in the Engineering Equation Solver software package. Application of the developed procedure is illustrated in a case with an exhaust gas temperature of 394.2 °C and mass flow rate of 0.306 kg/s. Configurations both with and without a recuperator are analyzed, and four working fluids (water, ethanol, toluene, and hexamethyldisiloxane) are compared. Of these fluids, ethanol could be recommended as the best when considering the organic Rankine cycle power output and the total area/volume of heat exchangers. For a total surface area of 10 m2 in the case without the recuperator, the power output values for ethanol, water, and toluene are 17.6 kW, 17.2 kW, and 15.8 kW, respectively; with the recuperator, the power output is slightly higher, but the total area of heat exchangers is considerably larger. Again, the best working fluid is ethanol: for a total surface area of heat exchangers of 24 m2, the power output values for ethanol, toluene, and hexamethyldisiloxane are 18 kW, 17.1 kW, and 15.8 kW, respectively. The presented procedure is useful both for the conceptual design of a complete waste heat recovery unit and for the optimization of all heat exchangers.

Fatigue failure of high-pressure oil-pipes of truck diesel engine

Abstract Fifteen cracked high-pressure oil-pipes of truck diesel engine were received for failure analysis. All the fifteen oil-pipes cracked on the concave side at the bend locations of oil-pipes without on the straight sections. The cracks were almost along the longitudinal of the oil-pipe but a slight deflection. The fatigue fracture was the failure mode of all the oil-pipes. The internal surface of oil-pipe on concave side of the bending location subjected to the maximum tangential stress due to the internal oil-pressure. The fatigue cracks initiated from the internal surface and propagated toward the external circle surface of oil-pipe under the alternating tangential stress resulting from the alternative oil-pressure inside pipe during service. The intense longitudinal micro-cutting marks were found on the internal surface of oil-pipe resulting from high-speed impact of hard and sharp grits in the process of grit-blasting internal surface of oil-pipe. Such micro-cutting marks acted as small notches and enhanced the stress concentration at the bottom of marks with ultimately resulting in crack initiation. The operating stress may become just high enough to make the micro-cutting marks on internal surface of oil-pipe at the bending location more critical. The stress intensification caused by the micro-cutting marks may exceed the fatigue limit of the pipe material.

A research on fuelling a truck diesel engine with hydrogen

The paper presents experimental and theoretical investigations results of a truck diesel engine fuelled with diesel fuel and hydrogen by diesel-gas method. The purpose of the paper is to reduce the level of the nitrogen oxides emission level and to improve the overall performances of the engine. The use of hydrogen represents a suitable method to reduce the classic fuels consumption, maintaining the energetic performances of the engine. The test bed situated in the Thermotechnics, Engines, Thermal Equipments and Refrigeration Instalations Department of University Politechnica of Bucharest was adapted for hydrogen fuelling of the truck diesel engine. The engine used for investigations is a turbocharged 10.2 l truck diesel engine which run at 1450 rpm and 40% engine load. By hydrogen fuelling if the investigated diesel engine a decrease has been achieved in the nitrogen oxides emission level and in the smoke emission level. Also the break energetic specific consumption decreased compared to the standard diesel engine. The theoretical investigations presented in tha paper are based on a semi-empirical corellation, used to simulate the nitrogen monoxide emission formation. The results of the experimental investigations confirm de viability of hydrogen as an alternative fuel for the diesel engine.

On the possibility to decrease the fuel consumption for a heavy-duty truck Diesel engine using the Turbo-compound method: a case study

The reduction of Diesel internal combustion engines emissions is one of the major concerns of the engines manufacturers. Despite the fact that the efficiency of the gas post-treatment systems has been significantly improved, decreasing the smoke and the soot from the cylinder inside remains a main research goal. This work is proposing a theoretical study on these pollutants formation for different kinds of direct injection methods. By dividing the in-cylinder injection the heat release characteristic could be modified, leading to different temperature and pressure levels. Using exhaust gas recirculation (EGR) the reduction of the gas temperatures might also be decreased, limiting NOx formation. To evaluate the level of the cylinder gas emissions formation a two-step procedure could be followed. First, by using a numerical calculation system the heat release characteristic can be highlighted concerning a Diesel engine with stratified injection; then, using an experimental relationship applying a large data base, the amount of the gas emissions can be subsequently provided. The authors propose some combinations between injection characteristics and EGR used fractions which could generate successfully results speaking in terms of NOx, soot and smoke formation.

Failure analysis of four-cylinder diesel engine crankshaft

In this article, failure analysis was examined in four-cylinder light-duty truck diesel engine crankshaft. The failure happened in service after 95,000 km of operation by fatigue crack growth which was initiated from a surface defect on the second crankpin from the crankpin–web fillet. For such objective, standard specimens were cut off from the crankshaft and examined to evaluate the mechanical properties. Some hardness and tensile tests were conducted, and spectrometry analysis was used in order to study the chemical composition of the crankshaft material. Also, for considering and evaluating the microstructure, microcracks, fracture surface and the cause of failure, optical microscopy and scanning electron microscopy equipped with energy-dispersive spectrometry were used. The morphology of the fracture surface shows that the failure happened in the second crankpin at the crankpin–web fillet of crankshaft where the stress concentration was the highest.

A detailed modeling study of radiative heat transfer in a heavy-duty diesel engine

In recent years, the importance of radiative heat transfer in combustion has been increasingly recognized. Detailed models have become available that accurately represent the complex spectral radiative properties of reacting gas mixtures and soot particles, and new methods have been developed to solve the radiative transfer equation (RTE). At the same time, the trends toward higher operating pressures and higher levels of exhaust-gas recirculation in compression-ignition engines, together with the demand for higher quantitative accuracy from in-cylinder CFD models, has led to renewed interest in radiative transfer in engines. Here an in-depth investigation of radiative heat transfer is performed for a heavy-duty diesel truck engine over a range of operating conditions. Results from 10 different combinations of turbulent combustion models, spectral radiation property models, and RTE solvers are compared to provide insight into the global influences of radiation on energy redistribution in the combustion chamber, heat losses, and engine-out pollutant emissions (NO and soot). Also, the relative importance of the individual contributions of molecular gas versus soot radiation, the spectral model, the RTE solver, and unresolved turbulent fluctuations in composition and temperature (turbulence–radiation interactions – TRI) are investigated. Local instantaneous temperatures change by as much as 100 K with consideration of radiation, but the global influences of radiation on heat losses and engine-out emissions are relatively small (in the 5–10% range). Molecular gas radiation dominates over soot radiation, consideration of spectral properties is essential for accurate predictions of reabsorption, a simple RTE solver (a first-order spherical harmonics – P1 – method) is sufficient for the conditions investigated, and TRI effects are small (less than 10%). While the global influences of radiation are relatively small, it is nevertheless desirable to explicitly account for radiation in in-cylinder CFD. To that end, a simplified CFD radiation model has been proposed, based on the findings reported here.

Optimization and application of Stirling engine for waste heat recovery from a heavy-duty truck engine

The requirements for cleaner engines and less fuel consumption force vehicle manufacturers to investigate new technologies on recovering from losses. As the main contributor to losses is the waste heat, studies are carried out to convert the waste heat to mechanical work. In this paper, an evaluation of Stirling engines is presented for waste heat recovery (WHR) from exhaust gases of a heavy-duty truck diesel engine. Maximum theoretical dimensionless shaft work for three types of Stirling engines are calculated and compared by optimizing selected parameters with a new dimensionless method. Results are used to size a WHR system that utilizes the thermal power of a commercial truck exhaust gas. Calculations done with exhaust gas temperatures measured during road tests show that, the WHR system with Beta-type Stirling engine is more effective than Alpha and Gamma types due to its higher power density. The WHR system presented provides more than 1.3% of ICE power output and about 1% reduction in fuel consumption, which offers Stirling engine as a reasonable option for WHR on heavy-duty truck engine.

Novel testing methods for screening the tribological performance of ring-liner surfaces

The piston system accounts for about the half of the frictional losses of internal combustion engines and requires special testing methods to understand and improve its function. The most common way to screen the surface performance is to rub ring/liner segments against each other in a reciprocating manner. However, short reciprocating tests have intrinsic low sliding speeds, unable to reach the mixed/hydrodynamic regimes found in the engine, especially at the mid-stroke. This paper presents a rotating test for the oil control ring, which has the largest frictional losses of all other rings. Both reciprocating and rotating tests were conducted using different in-house developed modules and fixtures. Twin land oil control rings against liners with two different finishes commonly used in heavy duty diesel truck engines were tested under similar loads and speeds as in a real engine. Engine oil 5W-30 and room temperature was used for all the tests. Sliding speed, load, friction force and electrical resistance were recorded during the tests. The results show a clear discrimination of the different liner finishes depending on the lubrication regime present.

Microstructure and fatigue fracture mechanism for a heavy-duty truck diesel engine crankshaft

The main goal of this research is the experimental and numerical study on the fatigue function and failure of the crankshaft of diesel engine of a heavy truck. To do this, a crankshaft of the diesel engine of a heavy truck that has gone under failure after traveling 955000 km, has been used. To examine the sources of this failure, several experimental studies have been carried out including chemical composition, the strength of the material, determining the hardness and the microstructure of the material. Besides, using an elastic–plastic three dimensional finite element method (FEM) model, the location of the maximum stress in the crankshaft was determined using the ‘‘complete crankshaft model’’ and ‘‘one crank model’’. Using the results of stress analysis, was a basis for the three-dimensional crack growth model and fatigue life estimation to determine the stress intensity factor and fatigue life considering the related parameters and boundary conditions method. At the final stage, using the results gotten from the given model for the fatigue crack growth, comparing it with experimental results, and examining the whole process, it was concluded that the scratches in crankpin region, was the main reason for the fatigue failure got from bending-torsional load-combination.

Fatigue failure of an intermediate transition block in fuel-injection pump fork assembly of a truck diesel engine

Abstract A truck diesel engine fuel-injection pump fork assembly failed after service of 50703 km. Fuel-injection pump fork assembly was constituted of the fork at the side of air-compressor pump, the intermediate transition block and the fork at the side of high-pressure oil-pump. General inspection in site indicated that the intermediate transition block fractured into four pieces. Fractographic analysis indicated that the block cracked due to fatigue. Four cracks occurred at respective U-shaped groove on the block and originated from the electro-discharge machined (EDMed) fillet root of U-shaped groove, where high stress concentration was caused by the geometry design. A remelted layer of about 5–20 μm was observed on the EDMed U-shaped groove surface. A lot of micro-cracks were presented within the remelted layer, which acted as stress raisers and led to a considerable reduction in fatigue strength of material. The cracks and surface imperfections associated with the remelted layer provided sites for fatigue crack initiation and subsequence propagation into the substrate material, which ultimately caused fatigue fracture of block. A finite element model of the block predicted that the highest stress concentration areas coincided with the first fracture zones and the maximum stress gradient direction was in agreement with the crack initiating direction.

Failure analysis of a truck diesel engine crankshaft

Abstract A truck engine crankshaft fractured during the service. The fracture occurred on the crankshaft big-end on which the timing-gear and the flywheel flange were coupled and the fracture location was just situated at the assembling gap between them. The short cracks inclined at about 45° to the shaft axis initiated from the surface of the crankshaft journal at the timing-gear side and mainly extended to the timing-gear side, leading to a zigzag cracking morphology on the journal surface. A complicated ratchet or star-shaped pattern of fracture typical of multiple fatigue cracks occurred on the fracture surface. The journal surface was locally induction-hardened. The surface hardness and the effective case depth on the hardened journal at the flywheel flange side corresponded to the specification. At the timing-gear side the surface hardness on the hardened journal was much lower than the specified lower limit and a low hardness region of 0.4 mm occurred on the most-surface of the hardened journal within which the hardness values were lower than the specified lower limit. The low surface hardness on the induction-hardened journal made fatigue resistance of the crankshaft decrease to lead to initiation and propagation of fatigue cracks in the weaker region. The assembling gap at which the fracture occurred was structure stress concentration site of the assembly constituted of the crankshaft, the timing-gear and the flywheel flange, equivalent to the deep notch. The excessive tightening of the timing-gear on the journal surface also contributed for the increasing of stress concentration. The fatigue crack origins were easy to initiate due to large stress concentration.

Modeling a Variable-Geometry Turbocharged Diesel Engine under Steady-State and Transient Conditions

AbstractIn the present work, a detailed thermodynamic model of a variable-geometry turbocharged (VGT) truck diesel engine has been built in the GT-Power environment in order to study its operation ...