Heavy-duty Diesel Engine Research Articles

Diagnosing Engine Oil Fuel Dilution by Viscosity Measurement in Heavy-Duty Diesel Engines Used in Railways

Kestirimci bakım yöntemleriyle karmaşık mühendislik sistemlerinde ortaya çıkabilecek arızalar önceden kontrol altına alınabilir. Titreşim analizi, ultrasonik test, termal kamera ile görüntüleme ve yağ analizi gibi uygulamalar kestirimci bakım yöntemleridir. Bu yöntemlerle, arıza henüz meydana gelmeden veyahut ciddi boyutlara ulaşmadan, sensörler aracılığıyla sistem ve ekipman gerekliliklerine göre belirlenmiş verilerin elde edilip incelenmesiyle muhtemel arızaların önüne geçilebilir. Bu çalışmada bir ağır dizel motor yağının (10W-40) içerisine ağırlıkça %1, %2, %5 ve %10 oranlarında biyodizel yakıtı konularak seyreltilmiştir. Yakıtla seyreltilmiş ağır dizel motor yağının viskozite ve yoğunluk performansları Anton Paar Automated Micro Viscometer ve DMA 4500 Density Meter kullanılarak 40, 60, 80 ve 90 ℃, sıcaklıklarında ölçülmüştür. Yağın içerisindeki yakıt miktarı seyrelmesinin viskozite ve yoğunluk değerleri üzerinden gözlemlenebildiği, seyrelmenin artmasıyla viskozitenin düştüğü fakat yoğunluğun arttığı ve yoğunluk üzerindeki değişmenin sıcaklıktan etkilenmediği fakat viskozite değerlerindeki ayrışmanın sıcaklıktan etkilendiği görülmüştür. Özellikle yakıt seyrelmesinin viskozite üzerindeki sıcaklığa bağlı etkisi %5 oranına kadar sabitken, seyrelme oranı artıkça sıcaklığa bağlı davranış değişiklik göstermiştir.

Transient Response of Turbocharged Compression Ignition Engine under Different Load Conditions

<div>In urban roads the engine speed and the load vary suddenly and frequently, resulting in increased exhaust emissions. In such operations, the effect of air injection technique to access the transient response of the engine is of great interest. The effectiveness of air injection technique in improving the transient response under speed transient is investigated in detail [<span>1</span>]; however, it is not evaluated for the load transients. Load step demand of the engine is another important event that limits the transient response of the turbocharger. In the present study, response of a heavy-duty turbocharged diesel engine is investigated for different load conditions. Three cases of load transients are considered: constant load, load magnitude variation, and load scheduling. Air injection technique is simulated and after optimization of injection pressure based on orifice diameter, its effect on the transient response is presented. The results reveal that air injection into the intake manifold is an effective technique to improve the turbo lag of a heavy-duty turbocharged diesel engine under the transient conditions of load.</div>

Experimental and Mechanism Study of Aerodynamic Noise Emission Characteristics from a Turbocharger Compressor of Heavy-Duty Diesel Engine Based on Full Operating Range

Heavy-duty diesel engines equipped with turbochargers is an effective way to alleviate energy shortage and reduce gas emissions, but their compressor aerodynamic noise emissions have become an important issue that needs to be addressed urgently. Therefore, to study the aerodynamic noise emission characteristics of a compressor during the full operating range, experimental and numerical simulation methods were used to analyze the aerodynamic noise emissions. The results showed that aerodynamic noise’s total sound pressure level (SPL) increased with increased speed under the test conditions. At low speeds, the total SPL of aerodynamic noise was affected by the mass flow of the compressor more obviously. The maximum difference of aerodynamic noise total SPL was 1.55 dB at 60,000 r/min under different mass flows. At the same speed, the compressor could achieve lower aerodynamic noise emissions by operating in the high-efficiency region (middle mass flows). In the compressor aerodynamic noises, the blade passing frequency (BPF) noise played a dominant role. The transient acoustic-vibration spectral characteristics and fluctuation pressure analysis indicated that BPF and its harmonic frequency noises were mainly caused by the unsteady fluctuation pressure. As the speed increased, the BPF noise contributed more to the total SPL of the aerodynamic noise, and its percentage was up to 75.35%. The novelty of this study was the analysis of the relationship between compressor aerodynamic noise and internal flow characteristics at full operating conditions. It provided a theoretical basis for reducing the heavy-duty diesel engine turbocharger compressor aerodynamic noise emissions.

Modelling and evaluating piston slap-induced cavitation of cylinder liners in heavy-duty diesel engines.

Cavitation erosion of cylinder liner seriously affects the operational reliability and service life of heavy-duty diesel engines. The accuracy of the modeling-based cavitation risk evaluation is limited by the unclear correspondence between cylinder liner vibration and coolant cavitation. This report is intended to investigate the correspondence between cylinder liner vibration and coolant pressure by combining vibration cavitation test, pressure gradient calculation, and visualization observation. The cavitation risk of the cylinder liner under piston slap is also quantitatively analyzed based on the nonlinear structural dynamics model. The results show that the occurrence of cavitation will cause a nonlinear relationship between the cylinder liner acceleration and the coolant pressure. The difference in cavitation risk for each cylinder is related to the structural modal characteristics of the crankcase. In addition, the effect of piston-liner clearance and piston pin offset on the cavitation risk is investigated based on the dynamics model.

Experimental and Numerical Investigations of Ultra-High Compressed Natural Gas Substitution Cases in a Heavy-Duty Diesel Engine

Experimental and Numerical Investigations of Ultra-High Compressed Natural Gas Substitution Cases in a Heavy-Duty Diesel Engine

An Experimental and Numerical Investigation to Improve the Efficiency of Combustion Systems for Heavy-Duty Applications

Abstract The European Union made new CO2 limits for heavy-duty vehicles mandatory in 2019, aiming to reduce the average tailpipe CO2 emissions by 15% in 2025 and by 30% in 2030, relative to the 2019 baseline. To meet these challenges, new technologies are needed to further reduce the fuel consumption of new heavy-duty trucks (“tank to wheel”) by using more efficient engines. The present study shows the pathways to improve thermal efficiency through better mixture formation and air utilization. This is achieved by designing a new piston bowl shape that has been numerically optimized iteratively to improve the air/fuel mixing by carefully considering the interaction between the fuel spray plume and the piston bowl. The computational fluid dynamics (CFD) model was calibrated using data from experimental studies with a heavy-duty single-cylinder diesel engine in the best efficiency and rated power operation. Heat transfer and turbulence models are studied to determine their influence on the combustion process and NOX emissions. Indicated thermal efficiency and air utilization were used to evaluate the performance of the piston bowl shape. For three different bowl shapes, the fuel spray interaction with the piston bowl was investigated and compared with the base bowl shape with a compression ratio CR = 18.3. Moreover, the effect of a higher CR of 21 on performance and mixture formation was analyzed for the optimized bowl shape. The higher CR of 21 was attained by a geometrically similar reduction of the optimized piston bowl. The results of the numerical and experimental investigations show that a CR of 21 leads to an increase in the indicated thermal efficiency of ∼3% in absolute values.

Hierarchical multi-time-scale predictive thermal management and fuel optimization for heavy-duty compression ignition engines

For heavy-duty diesel engines, NOX emissions reduction is strongly constrained by fuel efficiency. This paper presents a hierarchical model predictive controller (H-MPC) for coordinated control of tailpipe NOX emissions and fuel consumption. The H-MPC uses the separation of slow and fast dynamics that exist in the engine and its aftertreatment system. The controller is synthesized with an architecture in which a high-level MPC uses a longer prediction horizon compared to the low-level predictive controller which tracks the high-level controller command and manages the thermal dynamics of the aftertreatment system. Engine load preview enables the high-level controller to estimate the desired catalyst temperature ahead of time and addresses the selective catalytic reduction (SCR) slow thermal dynamics. Calculated by the high-level controller, the intake manifold pressure, and the start of injection (SOI) crank angle is used as reference trajectories in the low-level controller that regulates fast dynamical behaviors such as engine out NOX emissions. Hardware-in-the-loop (HIL) validation of this integrated H-MPC on a rapid prototype controller shows that when the SCR catalyst temperature is above light-off temperature (warmed-up condition), the engine operation is shifted to operate with the best fuel economy since the warmed-up SCR can efficiently reduce the engine-out NOX emissions. Results indicate that up to 0.8% benefit in cycle averaged BSFC along with a 13% reduction in tailpipe NOX compared to a stock engine calibration can be achieved with the coordinated engine and aftertreatment system through H-MPC.

Performance characterization of a selective catalytic reduction on filter aftertreatment system in a heavy-duty diesel engine tested on a laboratory dynamometer

Increasingly stringent emission regulations call for improvement in the current emissions control technology in heavy-duty diesel engines. In the existing aftertreatment system utilized in diesel engines, there is already a challenge with space and volume, and an attempt to add more components would lead to the consumption of more space and impracticable. The Selective Catalytic Reduction on Filter (SCRF)-an integration of Selective Catalytic Reduction (SCR) and Diesel Particulate Filter (DPF) in a single component, offers space saving and favorable thermal inertia opportunities. However, literatures are conflicting on the effect of the SCR and DPF activities on the operations of the SCRF, as both require NO2 for fast SCR reaction, and passive soot oxidation respectively. This paper presents a detailed experimental characterization of a Silicon-Carbide (Si–C) coated with Copper-Zeolite (Cu-Ze) catalyst SCRF after-treatment component in a heavy-duty diesel engine, evaluated on a laboratory dynamometer. The effect of particulate matter loading on the SCRF activities in steady state, and transient operations was investigated, with emphasis on the simultaneous utilization of NO2 between the passive soot oxidation activities and SCR reactions-which is a determinant of the NOx conversion efficiency. The SCRF was loaded from 0 g/L up to 5 g/L while passive regeneration and NOx conversion activities were investigated over steady and transient cycles. The investigation has shown that both NOx conversion efficiency and passive soot oxidation increase with particulate matter loading in the SCRF system of a heavy-duty diesel engine.

Influence of fuel injection parameters at low-load conditions in a partially premixed combustion (PPC) based heavy-duty optical engine

The study examined the effects of second injection timings and fuel injection pressures (FIPs) in a double-injection based partially premixed combustion (PPC) using a single-cylinder heavy-duty optical diesel engine equipped with two different configurations, namely all-metal and optical. The thermodynamic analysis of energy balance, exhaust emissions, and particulates characterization was conducted in an all-metal engine configuration. For the same base engine architecture, high-speed natural combustion luminosity, cool-flame, and electronically excited hydroxyl (OH*) chemiluminescence, and planar laser-induced fluorescence (PLIF) imaging of formaldehyde (HCHO-PLIF) were applied in the optical configuration. Additionally, 1D modeling using GT-Power was utilized to examine the distribution of heat transfer losses through the individual cylinder boundaries. The experiments were conducted at low-load conditions at a fixed fuel mean effective pressure (MEPfuel) using a primary reference fuel with a volumetric mixture of 50% n-heptane and 50% iso-octane (PRF50). The results demonstrated that for a fixed first injection, the second injection timing of −6°CA aTDC is the most favorable condition due to increased gross indicated efficiency, reduced exhaust losses, decreased uHC/CO/soot emissions with a slight compromise on heat losses and NOx emissions. Among the tested FIPs of 1200, 1500, and 1800 bar, 1500 bar showed higher efficiency, and overall lower energy losses and exhaust emissions. At higher FIPs, the overall flame development process revealed reduced luminous intensity with dispersed signals formed downstream of the nozzle due to increased premixed combustion. For 1800 bar FIP, both cool-flame and HCHO signals showed an increased rate of reaction zones close to the bowl-wall region from where the OH radicals developed. Not only the initial low- to high-temperature reaction transition was faster for 1800 bar FIP but the signal decay of HCHO signals by OH radicals was also rapid in the late cycle. These findings explained the root cause of increased heat transfer losses and higher uHC/CO emissions at 1800 bar FIP.

Role of Altitude in Influencing the Spray Combustion Characteristics of a Heavy-Duty Diesel Engine in a Constant Volume Combustion Chamber. Part I: Free Diesel Jet

Heavy-duty diesel engines operating in plateau regions experience deteriorated combustion. However, the lack of up-to-date information on the spray-combustion process limits the fundamental understanding of the role of altitude. In this work, the in-cylinder thermodynamic conditions of a real diesel engine operating under different altitudes were reproduced in a constant-volume combustion chamber (CVCC). The liquid spray, ignition, and combustion processes were visualized in detail using different optical diagnostics. Apart from predictable results, some interesting new findings were obtained to improve the understanding of free spray-combustion processes with different altitudes. The spatial distributions of ignition kernels provided direct evidence of higher peak pressure rise rates for high-altitude diesel engines. The percent of stoichiometric air was calculated to confirm that the net effect of altitude was an increase in the amount of air-entrained upstream of the lifted flame; therefore, the soot levels deduced from flame images were inconsistent with those from real engines, revealing that accelerating the soot oxidation process could effectively reduce engine soot emissions in plateau regions. Finally, a novel schematic diagram of the spray flame structure was proposed to phenomenologically describe the role of altitude in influencing the spray-combustion process of a free jet.

Combustion and emission characteristics of hydrotreated pyrolysis oil on a heavy-duty engine

Second-generation biofuel is promising to be applied in the field of long-haul transportation, aviation, and marine shipping. This work focuses on the ignition behavior, combustion process, and emission characteristics of hydrotreated pyrolysis oil. This biomass-derived oil was blended with marine gas oil from 10 to 30 wt% without a co-solvent or emulsifier. Tests were performed both on a combustion research unit and a commercial heavy-duty diesel engine setup. The results from the combustion research unit reveal that ignition delay increase as hydrotreated pyrolysis oil blend ratio increases at tested ambient conditions. Engine tests were first performed under factory settings at representative load/speed points based on the European stationary test cycle for benchmarking. Then start of injection and fuel pressure are varied to check the controllability and engine sensitivity of hydrotreated pyrolysis oil blends. It is shown that under engine conditions, the combustion characteristics and heat release are quite identical among hydrotreated pyrolysis oil blends and diesel. Though all cases present ultra-low particulate matter emissions, hydrotreated pyrolysis oil blends yield higher particulate matter emissions, which increase as the blend ratio increases. The particulate matter/NOx tradeoff is observed both for benchmarking tests and parameter study. The results indicate that the engine can run with HPO blends smoothly and safely without major modification.

Enhanced Exhaust after-Treatment Warmup in a Heavy-Duty Diesel Engine System via Miller Cycle and Delayed Exhaust Valve Opening

The exhaust after-treatment (EAT) threshold temperature is a significant concern for highway vehicles to meet the strict emission norms. Particularly at cold engine start and low loads, EAT needs to be improved above 250 °C to reduce the tailpipe emission rates. Conventional strategies such as electrical heating, exhaust throttling, or late fuel injection mostly need a high fuel penalty for fast EAT warmup. The objective of this work is to demonstrate using a numerical model that a combination of the Miller cycle and delayed exhaust valve opening (DEVO) can improve the tradeoff between EAT warmup and fuel consumption penalty. A relatively low-load working condition (1200 RPM speed and 2.5 bar BMEP) is maintained in the diesel engine model. The Miller cycle via retarded intake valve closure (RIVC) is noticeably effective in increasing exhaust temperature (as high as 55 °C). However, it also dramatically reduces the exhaust flow rate (over 30%) and, thus, is ineffective for rapid EAT warmup. DEVO has the potential to enhance EAT warmup via increased exhaust temperature and increased exhaust flow rate. However, it considerably decreases the brake thermal efficiency (BTE)—by up to 5%—due to high pumping loss in the system. The RIVC + DEVO combined technique can elevate the exhaust temperature above 250 °C with improved fuel consumption—up to 10%—compared to DEVO alone as it requires a relatively lower rise in pumping loss. The combined method is also superior to RIVC alone. Unlike RIVC alone, the RIVC + DEVO combined mode does not need the extreme use of RIVC to increase engine-out temperature above 250 °C and, thus, provides relatively higher heat transfer rates (up to 103%) to the EAT system through a higher exhaust flow rate. The RIVC + DEVO combined method can be technically more difficult to implement compared to other methods. However, it has the potential to maintain accelerated EAT warmup with improved BTE and, thus, can keep emission rates at low levels during cold start and low loads.

The effects of biodiesel produced from waste cooking oils on vibroacoustic properties of a heavy-duty diesel engine

This paper aims to investigate the vibroacoustic properties of biodiesel produced from waste cooking oils and petroleum-based diesel fuel depending on engine speed and load. Tests were conducted on a diesel engine with a 6 L cylinder volume which is used in today’s heavy-duty commercial vehicles. The engine tests were performed at various speeds and a constant engine load of 100 Nm. A vibration transducer and microphone were used to obtain the experimental data to determine vibroacoustic properties. The root mean square and coherence methods have been used for vibration analysis. The results show that the vibration amplitude of B100 at high engine speeds is slightly higher than that of pure petroleum-based diesel fuel (PBDF). B100 has a maximum 8.5% higher vibration amplitude relative to PBDF at an engine speed of 1500 rpm, where the engine is in the maximum torque intensity. Coherence analysis showed that the engine sound increased with increasing engine speed. The highest sound pressure level was 94.9 dB with B100 at an engine speed of 2000 rpm.

Comparative Assessment of sCO2 Cycles, Optimal ORC, and Thermoelectric Generators for Exhaust Waste Heat Recovery Applications from Heavy-Duty Diesel Engines

This study aimed to investigate the potential of supercritical carbon dioxide (sCO2), organic Rankine cycle (ORC), and thermoelectric generator (TEG) systems for application in automotive exhaust waste heat recovery (WHR) applications. More specifically, this paper focuses on heavy-duty diesel engines applications such as marine, trucks, and locomotives. The results of the simulations show that sCO2 systems are capable of recovering the highest amount of power from exhaust gases, followed by ORC systems. The sCO2 system recovered 19.5 kW at the point of maximum brake power and 10.1 kW at the point of maximum torque. Similarly, the ORC system recovered 14.7 kW at the point of maximum brake power and 7.9 kW at the point of maximum torque. Furthermore, at a point of low power and torque, the sCO2 system recovered 4.2 kW of power and the ORC system recovered 3.3 kW. The TEG system produced significantly less power (533 W at maximum brake power, 126 W at maximum torque, and 7 W at low power and torque) at all three points of interest due to the low system efficiency in comparison to sCO2 and ORC systems. From the results, it can be concluded that sCO2 and ORC systems have the biggest potential impact in exhaust WHR applications provided the availability of heat and that their level of complexity does not become prohibitive.

Toxicity of exhaust emissions from high aromatic and non-aromatic diesel fuels using in vitro ALI exposure system

The differences in the traffic fuels have been shown to affect exhaust emissions and their toxicity. Especially, the aromatic content of diesel fuel is an important factor considering the emissions, notably particulate matter (PM) concentrations. The ultra-fine particles (UFP, particles with a diameter of <100 nm) are important components of engine emissions and connected to various health effects, such as pulmonary and systematic inflammation, and cardiovascular disorders. Studying the toxicity of the UFPs and how different fuel options can be used for mitigating the emissions and toxicity is crucial. In the present study, emissions from a heavy-duty diesel engine were used to assess the exhaust emission toxicity with a thermophoresis-based in vitro air-liquid interface (ALI) exposure system. The aim of the study was to evaluate the toxicity of engine exhaust and the potential effect of 20 % aromatic fossil diesel and 0 % aromatic renewable diesel fuel on emission toxicity. The results of the present study show that the aromatic content of the fuel increases emission toxicity, which was seen as an increase in genotoxicity, distinct inflammatory responses, and alterations in the cell cycle. The increase in genotoxicity was most likely due to the PM phase of the exhaust, as the exposures with high-efficiency particulate absorbing (HEPA)-filtered exhaust resulted in a negligible increase in genotoxicity. However, the solely gaseous exposures still elicited immunological responses. Overall, the present study shows that decreasing the aromatic content of the fuels could be a significant measure in mitigating traffic exhaust toxicity.

Impact of diesel-hythane dual-fuel combustion on engine performance and emissions in a heavy-duty engine at low-load condition

Heavy-duty diesel vehicles are currently a significant part of the transportation sector, as well as one of the major sources of carbon dioxide (CO2) emissions. International commitments to reduce greenhouse gas (GHG) emissions, particularly CO2 and methane (CH4) highlight the need to diversify towards cleaner and more sustainable fuels. Hythane, a 20% hydrogen and 80% methane mixture, can be a potential solution to this problem in the near future. This research was focused on an experimental evaluation of partially replacing diesel with hythane fuel in a single-cylinder 2.0 L heavy-duty diesel engine operating in the diesel-gas dual fuel combustion mode. The study investigated different gas substitution fractions (0%, 38% and 76%) of hythane provided by port fuel injections at 0.6 MPa indicated mean effective pressure (IMEP) and a fixed engine speed of 1200 rpm. Various engine control strategies, such as diesel injection timing optimisation, intake air pressure and exhaust gas recirculation (EGR) were investigated in order to optimise the dual-fuel combustion mode. The results indicated that by using hythane energy fraction (HEF) of 76% combined with 125 kPa intake air boost and 25% EGR dilution, CO2 emissions could be decreased by up to 23%, while indicated thermal efficiency (ITE) was compromised by 1.5 percentage points, equivalent to a 3% reduction. Furthermore, soot was maintained below Euro VI limit and nitrogen oxides (NOx) level was held below the Euro VI regulation limit of 8.5 g/kWh assuming a NOx conversion efficiency of 95% in a selective catalyst reduction (SCR) system. Nevertheless, carbon monoxide (CO), unburned hydrocarbon (HC) and methane slip levels were considerably higher, compared to the diesel-only baseline. The use of a pre-injection prior to the diesel main injection was essential to control the heat release and pressure rise rates under such conditions.

Sustainability evaluation of a heavy-duty diesel engine used in railways

Heavy-duty diesel engines are essential power units for the Rail and Maritime transportation of people and goods. They are inevitable and consume large amounts of petroleum base fuel, producing substantial emissions. Since they are very bulky and costly to run and maintain, their performance, efficiency, and sustainability data are scarce, also. They are stationary constant-speed engines. Their efficiency values are relatively higher than conventional diesel engines. However, with newer pre and post-injections and fumigation techniques, those engines have significant room for improvement. This study thermodynamically examined a 16-cylinder, 4-stroke, and 90lt heavy-duty diesel engine with 1700 kW rated power output at 1500 rpm. Analyzes were performed on four different same-type engines archive data, obtained by permission, including different speeds and load conditions. Mean energetic and exergetic efficiency values were 12.84% and 11.92% at idling speeds of 650 rpm, 32.00%, and 29.70% at 1000 rpm, 31.35% and 29.10% at 1200 rpm, and 31.35% and 29.09% at the maximum speed of 1500 rpm. The waste-exergy ratio was 71%, the exergy destruction factor 45.5, the environmental effect factor was to be 2.44, and the exergetic sustainability index 0.41.

Study on the altitude adaptability of single-stage and two-stage turbocharging systems for a heavy-duty diesel engine

It is important to understand the altitude adaptability of the turbocharging system for maximizing its potential in the power recovery of the diesel engine at high altitudes. This study investigated the influence of altitudes ranging from 0 to 4500 m on the performance of the single-stage and two-stage turbocharging systems in a heavy-duty diesel engine. The research was conducted using a six-cylinder, four-stroke, turbocharged, direct-injection diesel engine. An altitude simulation test bench was used to simulate altitudes of 0 to 4500 m by adjusting the temperature and pressure. According to the test results, the altitude adaptability of different turbocharging systems was analyzed based on turbine work and turbocharger efficiency. It was concluded that the high-pressure stage regulation in the two-stage turbocharging system (HRT) strengthens the regulation ability in turbine work, effectively regulating the boost pressure and maintaining high turbocharger efficiency at different altitudes. The HRT can satisfy the regulation ability for altitudes ranging from 0 to 4500 m. The low-pressure stage regulation in the two-stage turbocharging system (LRT) weakens the regulation ability in turbine work and relies on reduction of the turbocharger efficiency to regulate the boost pressure. The LRT ineffectively regulates the boost pressure at low altitudes, with altitude adaptability from 1500 to 4500 m. Due to the exhaust temperature limitation, the waste-gate in the single-stage turbocharging system (WG) is not suitable for large-span regulation to satisfy the performance of the diesel engine at altitudes above 3,000 m compared with the HRT and LRT.

Development of Data-Driven Models for the Prediction of Fuel Effects on Diesel Engine Performance and Emissions

&lt;div&gt;A modelling tool has been developed for the prediction of fuel effects on the performance and exhaust emissions of a heavy-duty diesel engine. Recurrent neural network models with duty-cycle, engine control, and fuel property parameters as inputs were trained with transient test data from a 15-liter heavy-duty diesel engine equipped with a common-rail fuel injection system and a variable geometry turbocharger.&lt;/div&gt; &lt;div&gt;The test fuels were formulated by blending market diesel fuels, refinery components, and biodiesel to provide variations in preselected fuel properties, namely, hydrogen-to-carbon (H/C) ratio, oxygen-to-carbon (O/C) ratio, derived cetane number (CN), viscosity, and mid- and end-point distillation parameters. Care was taken to ensure that the correlation between these fuel properties in the test fuel matrix was minimized to avoid confounding model input variables.&lt;/div&gt; &lt;div&gt;The test engine was exercised over a wide variety of transient test cycles during which fuel rail pressure, injection timing, airflow, and recirculated exhaust gas flow were systematically varied. The resulting models could predict the transient engine torque and fuel consumption, and nitrogen oxide (NOx), soot, carbon monoxide (CO), total hydrocarbon (THC), and carbon dioxide (CO&lt;sub&gt;2&lt;/sub&gt;) exhaust emissions with good accuracy, indicating that the limited number of fuel property parameters selected as model inputs was sufficient to capture the fuel-related effects.&lt;/div&gt; &lt;div&gt;The modelling tool can also be used to estimate the relative contributions from changes in the individual fuel inputs to changes in exhaust emissions, and this is illustrated by means of an example blending study with crude-derived diesel fuel, biodiesel, and paraffinic gas-to-liquid (GTL) diesel fuel. This type of novel numerical analysis provides insights into fuel effects which are very difficult to achieve experimentally due to the high degree of intercorrelation between fuel properties that is usually present.&lt;/div&gt;

Influence of different loads and temperatures on solid lubricant-filled micro-dimples existing on both cylinder liner and piston ring

In order to meet the increasing demands of friction reduction and wear resistance in heavy-duty diesel engines, the refined design of surface topography of cylinder liner and piston ring (CLPR) has been a major concern. Based on electrolytic micro-texturing and electrochemical deposition methods, micro-dimples filled with solid lubricant have been separately applied to the CLPR surfaces. This double-sided textured design of CLPR exhibited significantly lower friction coefficient and wear depth than the non-dimpled CLPR when the lubricating oil containing zinc dialkyldithiophosphates (ZDDP) was used under different strengthening loads and temperatures. Solid lubricants were released from the double-sided textures, forming mutually transferable solid lubricant films on the sliding surface. Although various products containing molybdenum oxides, molybdenum sulfides, phosphate of different chain lengths, zinc compounds, iron sulfide, etc. Appeared in the tribochemical reactions of ZDDP and MoS2 with increasing temperature and load, but the lubricating effect was still maintained. These results can provide some insight into the design of CLPR surfaces in order to achieve a high quality tribofilm under heavy load conditions.