Diesel Engine Research Articles

A Silica Nano-Additive's Impact on the Performance and Emissions of a Diesel Engine Using DTBP Blended Low Viscous Waste Orange Peel Oil

<p>In the current study, the effect of silicon dioxide (SiO2) nano-additive mixed with Orange peel oil (OPO) as Biodiesel was investigated in relation to the operation and emission characteristics of a diesel engine. Orange peel oil was extracted from the orange Peel waste by using steam distillation method. The addition of Di-tetra-butyl-peroxide (DTBP) as a cetane booster is a novel strategy that has been attempted to improve the ignition patterns of OPO. The properties of customized fuel produced with a varying volume percentage DTBP and SiO2in 25,50 and 75 ppm in OPO were determined and compared to those of diesel. Uniform blending of nano-additives + DTBP with OPO is achieved by ultrasonication and isopropyl alcohol is used as a surfactant in order to stabilise the nano-additives. The physical and chemical characteristics of samples of pure and mixed fuel were identified and found in accordance with ASTM standards. Under varied loading conditions, the performance and emissions characteristics of various samples of fuel were studied. Addition of SiO2 nano-additive + DTBP increased the brake thermal efficiency (BTE) by 3.20-8.37% while decreasing brake specific fuel consumption (BSFC) by 4.18-11.25%. Carbon monoxide (CO), hydrocarbon (HC),nitrogen oxides (NOx) and smoke emissions were reduced by 5.61-12.84%, 9.65-19.05%, 0.89-7.71%, and 10.11-19.71%, respectively, when orange peel oil is blended with SiO2 and DTBP, and the mixture 10DTBP/90OPO -50SiO2 is found best comparable to ordinary diesel.</p>

Performance and Emission Characteristics of a High-Speed Diesel Engine Using a 20% Palm Oil Ester and Ethyl Alcohol Blend

Performance and Emission Characteristics of a High-Speed Diesel Engine Using a 20% Palm Oil Ester and Ethyl Alcohol Blend

Enhancing Fuel Efficiency and Emission Control in Diesel Locomotives through Auxiliary Power Units (APUs) in Neutral Conditions

This research investigates the imperative issue of fuel consumption and emissions in diesel locomotives during idle states, with a particular focus on the deployment of Auxiliary Power Units (APUs) in the neutral position (R-H). Diesel locomotives often exhibit a substantial fuel consumption rate, ranging from 23 to 25 litres per hour, during idling. This paper aims to elucidate the intricacies of optimising fuel consumption while concurrently addressing emission concerns without disrupting essential locomotive functions. In the quest for improved fuel efficiency and reduced emissions in locomotive operations, the utilisation of APUs in the neutral position (R-H) emerges as a pivotal point of investigation. APUs, which are auxiliary engines connected to the primary locomotive engine, play a significant role in achieving these objectives. The study delves into the health status and functionality of APUs during the locomotive’s neutral state, examining their impact on fuel consumption and emissions. A comprehensive understanding of this aspect is crucial for developing effective strategies to enhance locomotive performance while curbing environmental impact. It is crucial to recognise that locomotives serve essential functions even when idling, such as supplying compressed air to maintain brake pipe integrity, powering the locomotive control system, and ensuring the charging of batteries. Consequently, locomotive operators often refrain from shutting down the primary diesel engine to conserve fuel. This research, through a meticulous analysis of APUs in the neutral position, endeavours to strike a balance between fuel conservation and the preservation of critical locomotive functions. By exploring the intricacies of APU utilisation, this study contributes to the ongoing efforts aimed at achieving sustainability and improved fuel economy within the railway industry.

The fuel property and application prospect of water-containing biofuel from Clostridium acetobutylicum fermentation products

Biobutanol, a promising green alternative fuel, fermented from Clostridium acetobutylicum, while its high-cost and limited yield constraining its development. ABE (acetone-butanol-ethanol) and IBE (isopropanol-butanol-ethanol) are mixed fermentation products from non-edible biomass raw materials, using them together with water as alternative fuels will reduce industrial production costs and save fossil fuels. Therefore, this study conducted a multifaceted experimental evaluation on ABE/IBE mixed fuels with different water content, demonstrating that it has good water holding capacity when mixed with traditional fossil fuels. Taking ABE (3: 6: 1) as an example, its water holding capacity after mixing with diesel at 10–90 % is 0.37–7.83 % at 20 °C. Meanwhile, the particle size of ABE/IBE mixed fuels is about 2–30 nm, exhibiting a microemulsion with thermodynamic stability. The anhydrous or water-containing mixed fuel with the ratio of ABE (IBE) of 10%–50 % meets the range of the density and kinematic viscosity of diesel engine fuel. The mixed fuel is non-corrosive to copper without water, and a water content of about 3 % or higher will increase the risk of engine corrosion at 20 °C. Despite the addition of biofuel and water, studies on energy combustion performance and pollutant emission performance have found that appropriate addition of biofuel and water can produce higher power output and lower pollutant emissions than traditional fossil fuels, with ABE20W0.5 being the optimal. This study demonstrates the great potential of ABE and IBE as biofuels to achieve carbon neutrality goals, providing novel research direction for green alternative fuels in the future.

Experimental study of particulate matter emission for a diesel engine fueled with nanoparticles and biofuel / diesel blends

There has been a lot of interest in alternative fuels due to the depletion of petroleum supplies and growing environmental concerns. Biodiesel is made from renewable resources and is one of the many practical and beneficial fuel substitutes for fossil fuels. Recent advancements in nanotechnology have made it feasible to use nanoparticles as fuel additives for internal combustion engines. An earlier study suggested that these compounds might enhance engine performance. There has been a concern that this may increase the particulate matter emitted with the exhaust which adversely affects the air quality. The size-distribution of unregulated particulate matter (PM) emitted with exhaust gases is examined in this work. Under various load conditions, PM exhaust emissions were examined while keeping the engine running at a constant 1350 rpm. A nanoparticles of 50 parts per milligram of Aluminum oxide Al2O3 and Iron oxide Fe2O3 into the jatropha biodiesel / diesel fuel blend. When the engine is fueled with blend of diesel, biodiesel, and nanoparticles ternary fuel, it created fewer particulate matter emissions than the diesel/biodiesel binary blend which contains no nanoparticles. In comparison to pure diesel fuel, the diesel/biodiesel blend binary combination produced 10–15 % less PM1, PM2.5, PM7, and PM10 emissions which is very critical to air pollution problem with the fine/very fine particles.

Cold start performance of diesel engine at extremely low ambient temperatures and high altitudes: The superiority of premixing diethyl ether

The cold-start performance poses a primary challenge influencing the reliability of diesel engines operating in plateau and low-temperature regions. An experimental investigation was conducted to assess the cold-start performance of diesel engines with premixing diethyl ether (DEE), spanning altitudes from sea level to 4000 m and ambient temperatures of −20 °C and −40 °C. The diesel engine with premixing DEE exhibited successful cold starts at all these test conditions. In comparison, the diesel engine employing intake heating failed to reach idle speed in −40 °C high-altitude conditions. The premixed DEE could generate radicals, accompanied by a minor heat release preceding the injection of diesel, facilitating ignition. Furthermore, the premixed DEE enhanced fuel evaporation and facilitated the formation of combustible mixtures with higher equivalence ratios at low temperatures. Moreover, the fuel film resulting from wall impingement with premixing DEE was thinner than that with intake heating, contributing to decreased incomplete combustion losses. Energy analysis results revealed that the diesel engine employing premixing DEE demonstrated higher indicated thermal efficiency. The cold start assistance by premixing DEE proved to be much more effective, and the test engine could start smoothly under extremely low temperatures of −40 °C and high altitudes up to 4000 m.

Development of a semi-empirical physical model for transient NOx emissions prediction from a high-speed diesel engine.

With emissions regulations becoming increasingly restrictive and the advent of real driving emissions limits, control of engine-out NOx emissions remains an important research topic for diesel engines. Progress in experimental engine development and computational modelling has led to the generation of a large amount of high-fidelity emissions and in-cylinder data, making it attractive to use data-driven emissions prediction and control models. While pure data-driven methods have shown robustness in NOx prediction during steady-state engine operation, deficiencies are found under transient operation and at engine conditions far outside the training range. Therefore, physics-based, mean value models that capture cyclic-level changes in in-cylinder thermo-chemical properties appear as an attractive option for transient NOx emissions modelling. Previous experimental studies have highlighted the existence of a very strong correlation between peak cylinder pressure and cyclic NOx emissions. In this study, a cyclic peak pressure-based semi-empirical NOx prediction model is developed. The model is calibrated using high-speed NO and NO2 emissions measurements during transient engine operation and then tested under different transient operating conditions. The transient performance of the physical model is compared to that of a previously developed data-driven (artificial neural network) model, and is found to be superior, with a better dynamic response and low (<10%) errors. The results shown in this study are encouraging for the use of such models as virtual sensors for real-time emissions monitoring and as complimentary models for future physics-guided neural network development.

Development of a reduced primary reference fuel – oxymethylene dimethyl ether (PRF-OMEx) mechanism for diesel engine applications

Oxymethylene dimethyl ethers (OMEx), having a chemical formula of CH3O-(CH2O)x-CH3 where x varies from 1 to 5, have been widely considered as a promising fuel to partially replace diesel in CI engines in terms of reducing soot emissions. This work is focused on developing a reduced primary reference fuel (PRF)-OMEx chemical mechanism to better describe the combustion and emission characteristics of gasoline/diesel blends with OMEx. The novelty of this work lies in the fact that the OMEx part of the mechanism is represented not only by OME3 as done in most studies found in literature, but also with other OME chain lengths that is, OME2-4 which are considered to be optimum and better represent the commercial OMEx blends. For this purpose, a detailed OMEx mechanism is reduced by applying different reduction techniques considering a wide range of operating conditions including pressure, temperatures, equivalence ratios and fuel compositions. The result is merged with an already validated PRF mechanism to form a reduced PRF-OMEx mechanism consisting of 213 species and 840 reactions. The newly formed mechanism is validated against a wide set of experimental data including ignition delay times, laminar flame speeds and species concentration profiles. Furthermore, a rigorous set of numerical simulations for various diesel-OMEx blends in a compression ignition engine are carried out at two different operating points to validate the developed mechanism. Simulation results highlight that the developed mechanism not only replicates the experimental behavior in terms of in-cylinder pressure and heat release rate but exhibits a better combustion phasing closer to experimental data when compared with other mechanisms where only OME3 is utilized to represent OMEx. Overall, the developed PRF-OMEx mechanism proves to be realistic and suitable for application in engine combustion simulations involving gasoline/diesel and OMEx blends.

Combustion enhancement and emission reduction in RCCI engine using green synthesized CuO nanoparticles with Cymbopogon martinii methyl ester and phytol blends

Cymbopogon martini, also known as Palmarosa, is a grass species in the Cymbopogon genus, native to India and widely cultivated in tropical regions for oil production. Phytol, a constituent of chlorophyll, has garnered attention in the biofuels industry due to its potential for conversion into biodiesel through transesterification. Its abundance and renewable nature underscore its relevance for sustainable development. This study investigates the energy potential of waste Cymbopogon martinii Methyl Ester (CMME) in engine combustion systems using reactivity-controlled compression ignition (RCCI) in a single-cylinder, four-stroke diesel engine for low-temperature combustion. The process involves blending low-reactivity fuel (LRF), such as phytol (Acyclic diterpene alcohol and a constituent of chlorophyll), with high-reactivity fuel (HRF), namely CMME, in carefully monitored proportions. CMME25 is used as the primary fuel, supplemented with varying amounts of phytol (10 %, 20 %, and 30 %). Heat release rate (HRR) analysis indicates that phytol improves combustion efficiency up to a 20 % blend in RCCI mode. However, exceeding a 30 % phytol blend reduces brake thermal efficiency (BTE). RCCI mode also shows decreased nitrogen oxide and smoke emissions but increased hydrocarbon (HC) and carbon monoxide (CO) emissions. Improved homogeneity and ignition delay result in higher peak pressure and HRR compared to traditional methods. Further investigation focuses on the effects of CuO nanoparticles on a CMME25 and PHY20 % blend in RCCI mode. CuO nanoparticles (50–100 ppm) enhance brake thermal efficiency, improve combustion parameters (ignition delay, HRR, and cylinder pressure), and reduce emissions. The study concludes that a blend of CMME25+PHY20 % with 100 ppm CuO in RCCI mode is a promising alternative to traditional diesel fuel, offering a sustainable and efficient energy solution.

E-Heater Performance for Aftertreatment Warm-Up in a 48V Mild-Hybrid Heavy-Duty Truck over Real Driving Cycles

High-efficiency and low-emissions heavy-duty (HD) internal combustion engines (ICEs) offer significant GHG reduction potential. Mild hybridization via regenerative braking and enabling the use of an electric heater component (EHC) for the aftertreatment system (ATS) warm-up extends these benefits, which can mitigate tailpipe GHG and NOx emissions simultaneously. Understanding such integrated hybrid powertrains is essential for the system optimization of real-world driving conditions. In the present work, the potential of a low engine-out NOx (1.5–2.5 g/kWh range) ‘Low-NOx’ HD diesel engine and EHCs were analyzed in a 48V P1 mild-hybrid system for a class 8 commercial vehicle concept and compared with those in an EPA-2010-certified HD diesel truck as a baseline under real-world driving cycles, including those from the US, Europe, India, China, as well as the world harmonized vehicle cycle (WHVC). For analysis, an integrated 1-D vehicle model was utilized that consisted of models of the ‘Low-NOx’ HD engine, the stock ATS, and a production EHC. For the real driving cycles, ‘GT-RealDrive’-based vehicle speed profiles were generated for busy trucking routes for different markets. For each cycle, the effects of the Low-NOx and EHC performances were quantified in terms of the ATS warm-up time, engine-out NOx emissions, and net fuel consumption. Depending on the driving route, the regenerative braking fully or partly neutralized the EHC power penalty without a significant impact on the ATS thermal performance. For a two-EHC system, the fueling penalty associated with every second reduction in the warm-up time FCEHC (g/s) was several-fold higher for the real driving routes compared with the WHVC. Overall, while a multi-EHC setup accelerated the ATS warm-up, a single EHC integrated at the SCR inlet showed minimized EHC heating power, leading to a minimized fueling penalty. Finally, for the India and China routes, being highly transient, the P1 hybridization proved inadequate for GHG reduction due to the limited energy recuperation. A stronger hybridization was desirable for such driving cycles.

Multi-objective optimization of tribological properties of camshaft bearing pairs using DNN coupled with NSGA-II algorithm and TOPSIS

PurposeThis study aims to propose an optimization framework using deep neural networks (DNN) coupled with nondominated sorting genetic algorithm II and technique for order preference by similarity to an ideal solution method to improve the tribological properties of camshaft bearing pairs of internal combustion engine.Design/methodology/approachA lubrication model based on the theory of elastohydrodynamic lubrication and flexible multibody dynamics was developed for a V6 diesel engine. Setting DNN model as fitness function, the multi-objective optimization genetic algorithm and decision-making method were used to optimize the bearing pair structure with the goal of minimizing the total friction loss and the difference of the average values of minimum oil film thickness.FindingsThe results show that the lubrication state corresponding to the optimized bearing pair structure is elastohydrodynamic lubrication. Compared with the original structure, the optimized structure significantly reduces the total friction loss.Originality/valueThe optimized performance and corresponding structural parameters are obtained, and the optimization results were verified through multibody dynamics simulation.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-12-2023-0417/

Full load optimization of a hydrogen fuelled industrial engine

There are a large number of applications in which hydrogen internal combustion engines represent a sensible alternative to battery electric propulsion systems and to fuel cell electric propulsion systems. The main advantages of combustion engines are their high degree of robustness and low manufacturing costs. No critical raw materials are required for production and there are highly developed production plants worldwide. A CO2-free operation is possible when using hydrogen as a fuel. The formation of nitrogen oxides during hydrogen combustion in the engine can be effectively mitigated by a lean-burn combustion process. However, achieving low NOx raw emissions conflicts with achieving high power yields. In this work, a series industrial diesel engine was converted for hydrogen operation and comprehensive engine tests were carried out. Various measures to improve the trade-off between NOx emissions and performance were investigated and evaluated. The rated power output and the maximum torque of the series diesel engine could be exceeded while maintaining an indicated specific NOx emission of 1 g/kWh along the entire full load curve. In the low-end-torque range, however, the gap to the full load curve of the series diesel engine could not be fully closed with the hardware used.

Robust load-frequency control of islanded urban microgrid using 1PD-3DOF-PID controller including mobile EV energy storage

Electricity generation in Islanded Urban Microgrids (IUMG) now relies heavily on a diverse range of Renewable Energy Sources (RES). However, the dependable utilization of these sources hinges upon efficient Electrical Energy Storage Systems (EESs). As the intermittent nature of RES output and the low inertia of IUMGs often lead to significant frequency fluctuations, the role of EESs becomes pivotal. While these storage systems effectively mitigate frequency deviations, their high costs and elevated power density requirements necessitate alternative strategies to balance power supply and demand. In recent years, substantial attention has turned towards harnessing Electric Vehicle (EV) batteries as Mobile EV Energy Storage (MEVES) units to counteract frequency variations in IUMGs. Integrating MEVES into the IUMG infrastructure introduces complexity and demands a robust control mechanism for optimal operation. Therefore, this paper introduces a robust, high-order degree of freedom cascade controller known as the 1PD-3DOF-PID (1 + Proportional + Derivative—Three Degrees Of Freedom Proportional-Integral-Derivative) controller for Load Frequency Control (LFC) in IUMGs integrated with MEVES. The controller’s parameters are meticulously optimized using the Coati Optimization Algorithm (COA) which mimics coati behavior in nature, marking its debut in LFC of IUMG applications. Comparative evaluations against classical controllers and algorithms, such as 3DOF-PID, PID, Reptile Search Algorithm, and White Shark Optimizer, are conducted under diverse IUMG operating scenarios. The testbed comprises various renewable energy sources, including wind turbines, photovoltaics, Diesel Engine Generators (DEGs), Fuel Cells (FCs), and both Mobile and Fixed energy storage units. Managing power balance in this entirely renewable environment presents a formidable challenge, prompting an examination of the influence of MEVES, DEG, and FC as controllable units to mitigate active power imbalances. Metaheuristic algorithms in MATLAB-SIMULINK platforms are employed to identify the controller’s gains across all case studies, ensuring the maintenance of IUMG system frequency within predefined limits. Simulation results convincingly establish the superiority of the proposed controller over other counterparts. Furthermore, the controller’s robustness is rigorously tested under ± 25% variations in specific IUMG parameters, affirming its resilience. Statistical analyses reinforce the robust performance of the COA-based 1PD-3DOF-PID control method. This work highlights the potential of the COA Technique-optimized 1PD-3DOF-PID controller for IUMG control, marking its debut application in the LFC domain for IUMGs. This comprehensive study contributes valuable insights into enhancing the reliability and stability of Islanded Urban Microgrids while integrating Mobile EV Energy Storage, marking a significant advancement in the field of Load-Frequency Control.

An ideal investigation on conventional CRDI engine for optimum paradigm analysis of performance and exhaust emissions by using oxygenated and hydrogen fuel: An experimental green dual fuel approach

In this research, we look at how adding hydrogen to a conventional diesel engine (CRDI) with a diesel and sesame biodiesel blend (B20) changes the performance of engines. Depending on the load, H2 is pumped into the engine intake manifold at 7 lpm, 10 lpm, 60 %, 80 %, or 100 %. Due to its HCV and ability to reduce emissions in ways like as CO, CO2 and HC, hydrogen enrichment is beneficial to both the BTE and BSEC. However, this increase in emission of NOx is attributable to the higher EGT. The ignition delay (ID), in-cylinder pressure (ICP), and heat release rate (HRR) are all combustion parameters as well as combustion duration (CD), are all enhanced by the use of hydrogen. At 80 % load, the B20 + 7H2 fuel has 27.1 % higher BTE and 32.3 % lower BSEC compared to the pure diesel fuel. When compared to B20, NOx, Hydro Carbon, Carbon monoxide, and Carbon dioxide emissions go down by 13 %,34.6 %, 27 %, and 25.1 %, respectively. Under maximum throttle, the B20 + 7H2 blend reduces the HC, CO and C02 emissions and improves ICP 18.3 % and HRR by up to 18.78 %, while reducing CD by 14.6 %.

Dynamic evolution of residual stress upon manufacturing Al-based diesel engine diaphragm

Abstract As a thin-walled complex structure, the manufacturing of Al-based diesel engine diaphragms involves casting and heat treatment. Residual stress is introduced during the uneven temperature field in casting and heat treatment, as well as the plastic deformation and cutting heat during mechanical processing. This research investigates the evolution and accumulation models of residual stress in casting and heat treatment for Al-based diesel engine diaphragms using ProCAST and ABAQUS software, combining with the experimental tests. To mitigate residual stress, the optimal parameter combination for casting temperature, knockout temperature, and mold preheating temperature in casting process is explored. The results indicate that the knockout temperature has the most significant influence on casting residual stress, and mold preheating is beneficial for reducing residual stress. Despite improvements, some internal stress concentration areas persist on the knockout casting surface. Furthermore, T6 heat treatment proves to be effective in eliminating more than 50% of the residual stress.

Diesel direct injection and EGR optimization for a syngas-diesel dual-fuel generator operating at constant load

Diesel generators are widely used to produce electricity and heat in remote communities. However, their use contributes to harmful pollutant and greenhouse gas (GHG) emissions, negatively impacting the environment and public health. Syngas, which is a sustainable fuel, can play an important role in the transition from petroleum to renewable fuels. When used in dual-fuel diesel engines, it can contribute to reducing GHG emissions and the cost of transporting diesel, especially for rural and remote communities. This study investigates the effects of optimizing the diesel direct injection (DI) and exhaust gas recirculation (EGR) strategies on the combustion and emission performance of a syngas-diesel dual-fuel generator at constant load. The experiments were conducted using a 30-kW generator with a four-stroke, four-cylinder, turbocharged, and electronically controlled direct-injection diesel engine. The intake manifold of the engine was modified to allow introducing syngas upstream of the turbocharger. The syngas was simulated using individually controlled flow rates of hydrogen (H2), carbon monoxide (CO), carbon dioxide (CO2), and nitrogen (N2). The syngas flow rate was adjusted to replace 40% of the energy provided by diesel fuel while optimizing the diesel DI parameters such as the pilot injection timing, main injection timing and diesel direct injection rail pressure, as well as the EGR rate. The findings of this study reveal that optimizing diesel injection strategy and appropriately raising the EGR rate have a positive impact on the engine performance and emissions.

Biodiesel production from spent coffee grounds utilizing pomegranate/orange peel biochar as a green and renewable nanocatalyst: Compression ignition engine performance and emission

In this research, a novel pomegranate/orange peel-derived activated carbon (POPAC) green heterogeneous nanocatalyst was developed for the conversion of spent coffee grounds oil (SCGO) into biodiesel by ultrasonication and its application in diesel engine characteristics. The surface and texture attributes of the POPAC green nanocatalyst were scrutinized employing SEM, EDX, CO2-TPD, XRD, TEM, FTIR, Raman, and BET. Based on the response surface methodology (RSM) outcomes, the highest biodiesel efficiency employing POPAC green nanocatalysts was 95.24 %, which was attained at optimal conditions (i.e., molar proportion of 11.02, nanocatalyst content of 2.56 wt%, ultrasonic time of 30.77 min, and temperature of 60 0C). Moreover, the stability assessment demonstrated the high reusability of POPAC green nanocatalysts, with biodiesel efficiency remaining at 87.43 % even after the 7th round. Further, the kinetic survey exhibited that the biodiesel synthesis is endothermic and the conversion rate is enhanced by boosting the temperature. Besides, the impact of merging biodiesel with the diesel/biodiesel combination at diverse torques was scrutinized on the emission of exhaust output (e.g., UHC, NOx, CO, and CO2) and engine crucial characteristics (i.e., BP, EGT, BTE, and BSFC), and encouraging results were acquired. Briefly, due to special attributes including high catalytic performance, substantial recyclability, and eco-friendliness, POPAC green nanocatalyst are highly suggested for biodiesel generation.

Theoretical and experimental study of unsteady behavior of marine diesel engine under fluctuating back pressure condition

In order to meet the increasingly urgent emission reduction requirements, underwater exhaust has emerged as a promising technology for marine diesel engines and has received widespread attention in recent years. However, under fluctuating high back pressure conditions, the diesel engine as a whole operates in an unsteady state, with significant fluctuations in output power and exhaust temperature, posing a serious threat to their stability and safety. This paper focuses on the unsteady operating characteristics of diesel engines and its impact on the engine output power, efficiency and safety under fluctuating high back pressure conditions. Firstly, based on model order reduction and the first Lyapunov approximation theorem, the theoretical derivation reveals that the filling and emptying effects in the intake and exhaust pipes and the shaft moment of inertia of the turbocharger are the main causes of the unsteady of the engine under fluctuating high back pressure conditions. The factors influencing the strength of engine unsteadiness, including wave period, wave amplitude, mean back pressure and engine properties, are identified. Then, diesel engine experiments under different fluctuating high back pressure conditions are performed and the conclusions derived from the theoretical analysis are validated through experiments. Based on the research results mentioned above, this paper proposes a criterion to determine the unsteadiness of diesel engines. Through comparison with experimental data, it is found that this criterion effectively reflects the strength of engine unsteadiness, with a correlation coefficient of 0.9169 with the unsteady parameter.

Numerical analysis on lubrication failure of main bearings with lemon-shaped bearing shells in high-power diesel engine

The lubrication status of crankshaft main bearings significantly affects the stability and reliability of diesel engine operation. This paper primarily investigates the severe failure of main bearings during developing an industrial high-power 6 V diesel engine and analyzes the causes of bearing failure. Main bearings using lemon-shaped bearing shells exhibited failure after a short period of operation. Based on the multi-body dynamics model, average Reynolds equation, and contact model, a lubrication model for the main bearings was established, and the lubrication characteristics of each main bearing were simulated. The research shows that the abrupt peaks of the lemon-shaped bearing shells on the first and second main bearings are located within the area where the bearings suffer from burst pressure, resulting in additional hydrodynamic pressure and asperity contact pressure on the bearing surfaces. This makes the bearing surface prone to wear and high temperature, which are the primary causes of bearing failure. Under the operating conditions, surface damage of the bearings leads to particle abrasion and high temperature. Subsequently, the lubricating oil gradually deteriorates with the combined action of high temperature and wear particles, causing the main bearings to blacken and adhesive wear.

Comparative Analysis of CO2 Emissions, Fuel Consumption, and Fuel Costs of Diesel and Hybrid Dredger Ship Engines

There is a consensus on the need to reduce the emissions of carbon compounds. The increase in global greenhouse gas (GHG) emissions in the maritime industry poses a serious challenge to environmental sustainability, climate change, and the operating costs of ships. This article shows how hybrid versus diesel propulsion technology for ships can help reduce carbon dioxide (CO2) emissions and fuel consumption, and how these changes can be achieved. The need to reduce exhaust emissions and the increasing need for the shipping industry to seek alternative fuels means that existing regulations for marine engines and engine emissions are being updated almost constantly and new regulations are being formulated. The cost implications of the new regulations may lead to an increase in emissions as engines with lower fuel consumption are chosen, i.e., larger marine engines. Alternative approaches are needed to reduce CO2 emissions and fuel consumption, which could ultimately lead to hybrid propulsion for ships. This paper examines the current state of greenhouse gas emissions in shipping by analyzing the CO2 emissions and operating costs of two ships of the same type with similar technical and technological characteristics and different propulsion systems to gain insight into the problem. This paper compares the reductions in CO2 emissions, fuel consumption, and fuel costs for two suction hopper dredgers with standard diesel and hybrid propulsion. The technical characteristics, CO2 emissions, fuel consumption, and price of the two ships were analyzed to determine the advantages and disadvantages of each propulsion system. The novelty of this study is that two suction hopper dredgers from the same company with similar technical–technological characteristics but different propulsion systems were used for the case study and a mathematical procedure for calculating CO2 and other greenhouse gasses was presented in comparison, all to determine to what extent and in what way the hybrid propulsion system of a ship can contribute to reductions in CO2 emissions and fuel costs at the ship and company levels compared to a standard diesel propulsion system. This comparative analysis shows how much lower CO2 emissions, fuel consumption, and fuel cost savings can be expected when using a hybrid propulsion system compared to a standard diesel propulsion system. Finally, a conclusion is drawn on the efficiency and environmental compatibility of the two systems.