Improve Engine Efficiency Research Articles

Variable Valve Timing (VVT) Modelling by Lotus Engine Simulation Software

Variable valve timing (VVT) is an advanced modern technique applied in internal combustion engines by altering the valve lift event timing. This work aims to contribute to the continuing industrial VVT development to improve engine efficiency, fuel consumption and performance. To observe the influence on the spark-ignition (SI) engine’s performance, four valve timing strategies are selected carefully by varying the intake and exhaust valve timing. Lotus Engine Simulation, a simulation engineering software, is adapted in this study. The engine characteristics used in this modelling are spark engine, multicylinder, four strokes, port injection fuel system and constant compression ratio. A comparison between a conventional standard exhaust/intake valve timing and three other different timing cases is carried out. Results reveal that the overlap case of 98° showed a good brake-specific fuel consumption by approximately 3% less than the conventional case. An improvement of 6.2% for volume efficiency and 2.9% in brake thermal efficiency is also reported.

Study on leading-edge trenched holes arrangement under real turbine flow conditions

Turbine guide vane faces extremely high thermal load, especially on the leading edge region. In order to enhance cooling performance, the present study investigates the effects of leading-edge film cooling arrangements by adiabatic and aero-thermal coupled simulation. The three-row cooling design of the 25° inclined angle with the trenched holes is used to replace five-row showerhead holes. The model is employed after conducting the numerical validation. The results show that at coolant mass flow of 0.00171 kg/s, three-row showerhead film cooling with trenched holes can provide higher laterally averaged adiabatic cooling effectiveness than three-row round holes. It can also improve cooling performance in most of the leading-edge regions, compared with five-row showerhead cooling arrangements. The three-row cooling design with trenched holes can still obtain the highest area-averaged effectiveness on either the suction side or the pressure side of the leading edge. Besides, the trenched holes are also beneficial to the reduction of the aerodynamic losses. In the aero-thermal coupled simulation, the improvement of the three-row cooling design with trenched holes decreases because of the internal cooling effect. It is also proved that the transverse trench would not lead to a local high temperature region on the metal surface. The trenched configuration above can be used on the first-stage turbine vane to increase turbine inlet temperature, improve engine efficiency, and prolong engine life.

The Pressure Control of High Pressure Tubing Together with Problems about Carbon Deposit

In this article, we solve the controlling problems raised by the problem for the part A of the 2019 Chinese University Students Mathematical Modeling Competition—Pressure Control of High Pressure Tubing. Also we have considered the actual problems that may arise, and give a feasible controlling plan. This article is based on fluid mechanics model and micro-element thinking. With the help of software tools such as Excel, Microsoft Visual Studio, and C++ language for programming calculations and simulations, we finally give a feasible solution to stabilizing the pressure in the high-pressure oil pipe, which provides a reference to improve engine efficiency.

선박폐열회수시스템을 위한 외향반경류형 터빈 기본 설계

Based on the IMO 2020 Regulation and EEDI Phase 3, international demand for eco-friendly ships is growing. The waste heat recovery system on vessels has a potential to reduce CO₂ emissions of 5 to 10% while improving engine efficiency. This study aims to design ORC (Organic Rankine Cycle) and radial outflow turbine for the waste heat recovery system using exhaust gas in vessels. A designed cycle is simple ORC using R245fa as a working fluid. 1D turbine design utilizes Euler`s turbomachinery equation, specific speed, specific diameter and commercial software. Once the initial model of the ROT (Radial Outflow Turbine) was designed, a case study was conducted by different numbers of stage. For a case study, we chose a 5-stage ROT and analyzed its design and off-design performances using rotational speed, inlet total pressure and temperature. The designed 5-stage ROT has the power output of 480.9 kW and total-to-static efficiency of 86.8% at the design point. The off-design performance can be a preliminary guidance to operate an ROT in practice.

Optimization Studies of AC4CH Material in the Cylinder Block of a Diesel Engine Application

The reduction of the weight of the engine of a vessel or an automobile can result in improved engine efficiency and lower CO2 emissions. Therefore, this study was conducted to improve the mechanical properties of the AC4CH alloy, an alternative to cast iron for engine fabrication, through the addition of Si and Mg to aluminum. The mechanical properties of the alloy were improved through refinement of the Si structure, grain refinement, and heat treatment. In addition, the applicability of a cylinder block fabricated with the modified AC4CH alloy to a diesel engine was validated through a 300 h durability test.

SPRAY VISUALIZATION OF HYDROTREATED VEGETABLE OIL UNDER SIMULATED DIESEL ENGINE CONDITION

The diversity of alternative fuels and the corresponding variation in their physical and chemical properties, coupled with simultaneous changes in advanced techniques for CI-engine, needed to improve engine efficiency and emissions. Hydrotreated Vegetable Oil (HVO), seen as a promising substitution for petrol-diesel, and diesel fuel (mixed of 7% palm-biodiesel or B7) were analyzed on fuel properties. Then, the influence of these fuel properties on spray characteristics in constant volume combustion chamber were evaluated under conditions of single hole injector of 200m diameter, injection pressure of 100MPa, constant back pressure of 4.0MPa and energizing time of 2.5ms. The results show that HVO had smaller in viscosity (18.48%), density (5.52%), sulfur content, distillation under T50, T90 and higher in derived cetane index (27.2%), heating value (2.2%), respectively, compared to diesel. Spray characteristics of HVO had the same propensity with diesel fuel. HVO revealed a slightly shorter in penetration length (5%) during fully developed zone, a larger spray cone angle (from 0.2 to 1.1 degree wider in quasi-steady state). Both fuels had a similar maximum spray velocity reaching at 5mm to 10mm from nozzle orifice. Also observed was an increase in spray volume of HVO.

Experimental investigation of rice bran biodiesel with hydrogen enrichment in diesel engine

ABSTRACT In the ongoing decades, the vitality interest for transport and the modern part has expanded extensively. Fossil fuels which are the significant fuel hotspot for quite a long time are not anymore feasible. Biodiesel has emerged as an effective immediate alternative for partial replacement of the exhausting petroleum fuels. Hydrogen has also considered as one of the other promising gaseous fuels due to its remarkable combustion parameters which improve engine efficiency and emits lower pollutants. In the present investigation hydrogen enrichment with neat diesel (ND), and rice bran biodiesel (RB20) has been attempted to run the diesel engine. The hydrogen is inducted in the intake manifold at a constant flow rate of 13 l/min. Results indicate that compared to neat diesel, the rice bran biodiesel with hydrogen (RB20+ H2) exhibits a 2.31% increase in BTE and a 7.4% reduction in BSFC at 90% loading condition. Further, the emission characteristics like carbon dioxide, carbon monoxide, and smoke, decrease by 7%, 10%, and 3.6%, respectively, expect the NOₓ, which is increased by 10%. The hydrogen enrichment increases the in-cylinder pressure and net heat release rate. Further, hydrogen enrichment with the biodiesel blend shows better results as compared to neat diesel fuel.

An Evaluation of the Effectiveness and Reliability of the Machines Using the Overall Equipment Effectiveness (OEE) and Reliability Analysis Methods at the Tea Leaf Processing Plant PT. Perkebunan Nusantara IV Unit Bah Butong

The Tea Leaf Processing Plant PT. Perkebunan Nusantara IV Unit Bah Butong is an industry that motion in the tea leaf processing. The process of production is supported by a number of interdependent machines and tools to achieve optimal productivity. The problem is that frequent machine failure is considered to be interfering with the production process resulting from maintenance’s un-maximum. Thus need evaluation of the effectiveness and reliability of machines in order to maximize maintenance in order to reduce machine failure. The purpose of this study is to know the value of the effectiveness production engine by calculating the value of the Overall Equipment Effectiveness (OEE), identifying the effectiveness of the engine by measuring six big losses, calculating the reliability of the engine by adding analysis and improving the maintenance schedule to improve engine efficiency, and predicting OEE’s values after maintenance repairs were made. The value of this journal is expected to be an input to companies to know the value of the effectiveness machines and the reliability of the entire machine system if maintenance is done according to the recommended MTTF maintenance program.

A comprehensive study on the performance and emission characteristics of a diesel engine with the blends of diesel, jojoba oil biodiesel, and butylated hydroxyl anisole as an alternative fuel

ABSTRACT Supplementary requests for nonrenewable-based fossil fuel and a massive increase in atmospheric air quality, due to the excess dependency on nonrenewable fuel especially diesel, offered a view to find energy production from a renewable resource for the unaltered compression-ignition engine. The present work intends to evaluate the engine characteristics, namely, emission and performance of a Jojoba oil biodiesel (JB100) fueled diesel engine with Butylated hydroxyl anisole (BHA) as an antioxidant at distinct mass fractions (50, 75, and 1000 ppm). The experimentation was conducted in a single cylinder, water-cooled, direct injection compression ignition (DICI) diesel engine with 1500 rpm at constant speed. The experimental work on the compression-ignition engine revealed that the blending of BHA to JB100 leads to improved engine efficiency through diminished fuel utilization. The findings exhibited that the addition of BHA leads to an upgraded production of emission levels from the engine (especially hydrocarbon, carbon monoxide, and smoke). BHA addition to JB100 has a substantial effect on decreasing NOx emission. JB100+ BHA1000 showed lower NOx compared to all other prepared fuel samples. Based on experimentation, JB100 was observed as a noticeable substitute for conventional fuel and BHA presence helps to improve the performance and emission parameters. JB100+ BHA1000 sample was deliberated advantageous compared to JB100+ BHA750 and JB100+ BHA500 based on its engine characteristics.

Using deep neural networks to diagnose engine pre-ignition

Engine downsizing and boosting have been recognized as effective strategies for improving engine efficiency. However, operating the engines at high load promotes abnormal combustion events, such as pre-ignition and potential superknock. Currently the most effective method for detecting pre-ignition is by using in-cylinder pressure sensors that have high precision and sensitivity, but also high cost. Due to rapid advances in automotive technology such as autonomous driving, computer-aided designs and future connectivity, we propose to use a complimentary data-driven strategy for diagnosing abnormal combustion events. To this end, a data-driven diagnostics approach for pre-ignition detection with deep neural networks is proposed. The success of convolutional neural networks (CNNs) in object detection and recurrent neural networks (RNNs) in sequence forecasting inspired us to develop these models for pre-ignition detection. For a cost-effective strategy, we use data from less expensive sensors, such as lambda and low-resolution exhaust back pressure (EBP), instead of high resolution in-cylinder pressure measurements. The first deep learning model is combined with a commonly used dimensionality reduction tool–Principal Component Analysis (PCA). The second model eliminates this step and directly processes time-series data. Results indicate that the first model with reduced input dimensions, and correspondingly smaller size of the network, shows better performance in detecting pre-ignition cycles with an F1 score of 79%. Overall, the proposed deep learning approach is a promising alternative for abnormal combustion diagnostics using data from low resolution sensors.

Development and Application of Ion Current/Cylinder Pressure Cooperative Combustion Diagnosis and Control System

The application of advanced technologies for engine efficiency improvement and emissions reduction also increase the occurrence possibility of abnormal combustions such as incomplete combustion, misfire, knock or pre-ignition. Novel promising combustion modes, which are basically dominated by chemical reaction kinetics show a major difficulty in combustion control. The challenge in precise combustion control is hard to overcome by the traditional engine map-based control method because it cannot monitor the combustion state of each cycle, hence, real-time cycle-resolved in-cylinder combustion diagnosis and control are required. In the past, cylinder pressure and ion current sensors, as the two most commonly used sensors for in-cylinder combustion diagnosis and control, have enjoyed a seemingly competitive relationship, so all related researches only use one of the sensors. However, these two sensors have their own unique features. In this study, the idea is to combine the information obtained from both sensors. At first, two kinds of ion current detection system are comprehensively introduced and compared at the hardware level and signal level. The most promising variant (the DC-Power ion current detection system) is selected for the subsequent experiments. Then, the concept of ion current/cylinder pressure cooperative combustion diagnosis and control system is illustrated and implemented on the engine prototyping control unit. One application case of employing this system for homogenous charge compression ignition abnormal combustion control and its stability improvement is introduced. The results show that a combination of ion current and cylinder pressure signals can provide richer and also necessary information for combustion control. Finally, ion current and cylinder pressure signals are employed as inputs of artificial neural network (ANN) models for combustion prediction. The results show that the combustion prediction performance is better when the inputs are a combination of both signals, instead of using only one of them. This offline analysis proves the feasibility of using an ANN-based model whose inputs are a combination of ion current and pressure signals for better prediction accuracy.

Methodological analysis of variable geometry turbine technology impact on the performance of highly downsized spark-ignition engines

New generation of spark ignition (SI) engines are expected to represent most of the future market share in a context of powertrain hybridization. Nevertheless, the current technology has still critical challenges in front to meet incoming CO2 and pollutant emissions standards, so new technologies are emerging to improve engine efficiency. In parallel to combustion concepts, a key required trend is downsizing based on high engine boosting. New turbocharger technologies, such as variable geometry turbines (VGT), become suitable for its application under the demanding operating conditions of SI engines. In this work, a methodology for the analysis of the VGT usage in comparison with traditional waste-gate (WG) turbine is presented. From experimental data obtained in engine test cell, a theoretical analysis aimed at ensuring full control on turbine boundary conditions, such as combustion variability, compressor map or engine calibration, was conducted. Taking advantage of highly validated and physically representative 1-D gas-dynamics and turbocharger models, the engine performance is discussed as a function of the turbine technology at full and partial load in a wide range of engine speed at the same time as the altitude impact is addressed. In all, it was found that VGT technology shows less limitations in extreme working conditions, such as low- and high-end torque regions, where the WG technology represents a limitation in terms of the maximum power output. Full load differences become more even more evident in altitude working conditions. When it comes to partial loads, differences in fuel consumption are minor, but potentially beneficial for VGTs.

Large Eddy Simulation with dense fluid approximation and experimental study on the commercial diesel trans-critical injections

Diesel supercritical combustion can effectively improve engine efficiency and reduce harmful emissions. Therefore, studying the trans-critical injection characteristics of diesel is of great significance for further understanding of diesel supercritical combustion. In this work, a diesel trans-critical injection experiment is first carried out to test the liquid and vapor jet structure. Then the six-component surrogate of diesel is used to represent the thermo-physical properties of diesel in the range from subcritical state to supercritical state. Based on these thermo-physical properties, the dense fluid approximation method based on Large Eddy Simulation is applied to simulate the trans-critical injection processes of diesel. The results show that there is only a short continuous cold liquid core near the nozzle exit in the diesel trans-critical injection. The dense fluid approximation method based on diesel six-component surrogate and Large Eddy Simulation can accurately predict the diesel trans-critical injection properties. In order to accurately simulate the diesel trans-critical injection, it is necessary to develop a reliable diesel surrogate that can accurately emulate diesel various properties. Generally, this work is helpful to understand the characteristics of diesel trans-critical injections, and the numerical model is valuable for the optimal design of diesel engines.

A scientometric analysis and critical review of gas turbine aero-engines control: From Whittle engine to more-electric propulsion

The gas turbine aero-engine control systems over the past eight decades have been thoroughly investigated. This review purposes are to present a comprehensive reference for aero-engine control design and development based on a systematic scientometric analysis and to categorize different methods, algorithms, and approaches taken into account to improve the performance and operability of aircraft engines from the first days to present to enable this challenging technology to be adopted by aero-engine manufacturers. Initially, the benefits of the control systems are restated in terms of improved engine efficiency, reduced carbon dioxide emissions, and improved fuel economy. This is followed by a historical coverage of the proposed concepts dating back to 1936. A comprehensive scientometric analysis is then presented to introduce the main milestones in aero-engines control. Possible control strategies and concepts are classified into four distinct phases, including Single input- single output control algorithms, MIN-MAX or Cascade control algorithms, advanced control algorithms, More-electric and electronic control algorithms and critically reviewed. The advantages and disadvantages of milestones are discussed to cover all practical aspects of the review to enable the researchers to identify the current challenges in aircraft engine control systems.

Analysis of Cyclic Variation Using Time-Resolved Tomographic Particle-Image Velocimetry

<div class="section abstract"><div class="htmlview paragraph">To achieve the strict legislative restrictions for emissions from combustion engines, vast improvements in engine emissions and efficiency are required. Two major impacting factors for emissions and efficiency are the reliable generation of an effective mixture before ignition and a fast, stable combustion process. While the mixture of air and injected fuel is generated by highly three-dimensional, time-dependent flow phenomena during the intake and compression stroke, the turbulent flame propagation is directly affected by the turbulence level in the flow close to the advancing flame front. However, the flow field in the combustion chamber is highly turbulent and subject to cycle-to-cycle variations (CCV). To understand the fundamental mechanisms and interactions, 3D flow measurements with combined high spatial and temporal resolution are required. Furthermore, most studies utilize velocity decompositions based on the standard Reynolds decomposition that yields a mean flow velocity and a fluctuation velocity, which comprises of fluctuations from CCV and turbulence. Therefore, time-resolved tomographic PIV measurements are coupled with a triple-velocity decomposition method based on a multiple-snapshot POD to investigate in-cylinder velocity fluctuations from cyclic variability. The method is extensively discussed and the most important steps are highlighted by examples. The results illustrate that the method yields valid findings, which allow a comparison of the impact of CCV between two parameter sets or between engine cycles.</div></div>

Tribological characterization of potential crankshaft bearing steels for roller bearing engines

A crankshaft roller bearing internal combustion engine (ICE) offers a five percent or more improvement in overall engine efficiency and, thereby, a reduction in a five percent of CO2 emissions, compared to a plain bearing supported crankshaft. Current forged crankshaft steels represent the limiting factor of the rolling component, therefore, a replacement of the crankshaft steel is required. Apart from this, the tribology of the rolling contacts has been shown to be detrimental when lubricated with current engine oils. Therefore, this paper investigates the tribological performance of potential crankshaft bearing steels, i.e. DIN C56E2 (G55); DIN 50CrMo4 (G50); and DIN 100Cr6 (G3), while utilizing a state-of-the-art low viscosity 0W20 engine oil and under conditions prevalent to ICE. For this, damage mode investigation was performed in a disc-on-disc setup. Based on the results, wear damage of DIN 100Cr6 discs was shown to be dependent on the steel grade of which the counterpart disc was made from and surface hardness difference between both discs. In addition, surface fatigue and wear damage can be completely eliminated by selecting a proper surface roughness and hardness combination. Also, while under an elevated roughness level, engine oil was shown to promote both surface fatigue and wear damage through the work of ZDDP additives, which under extreme conditions can act as an extreme pressure (EP) additive. The residual stress measurements using the XRD technique revealed relatively high compressive residual stresses for G55 and G50 in comparison to G3 steel after surface induction hardening. In addition, no significant changes in residual stress for G55 and G50 were observed after the test. In contrast, relatively high tensile stress was observed for G3 near the surface region. This suggests that the most commonly used 100Cr6 bearing steel, in this case, is the most susceptible to surface fatigue.

Investigation of Gasoline Compression Ignition for Combustion Control

Abstract Future emission regulations for internal combustion engines require increasingly stringent reductions of engine-out emissions, especially NOx and particulate matter (PM), together with the continuous improvement of engine efficiency. In the current scenario, even though compression-ignited engines are still considered the most efficient and reliable technology for automotive applications, the use of diesel-like fuels has become a critical issue, since it is usually not compatible with the required emissions reduction. A large amount of research and experimentation is being carried out to investigate the combined use of compression-ignited engines and gasoline-like fuels, which proved to be very promising, especially in case the fuel is directly injected in the combustion chamber at high pressure. This work investigates the combustion process occurring in a light-duty compression-ignited engine while directly injecting only gasoline. A specific experimental setup has been designed to guarantee combustion stability over the whole operating range that is achieved controlling boost pressure and temperature together with all the injection parameters of the multijet pattern. The analysis of the experimental data clearly highlights how the variation of the control parameters affect the ignition process of small amounts of directly injected gasoline and the maximum achievable efficiency. In particular, the analysis of the sensitivity to the injection parameters allows identifying an ignition delay model and the key control parameters that might be varied to guarantee a robust control of combustion phasing within the cycle.

Significant Impact of Flash Boiling Spray on In-Cylinder Soot Formation and Oxidation Process

The use of flash boiling atomization has demonstrated potential in improving engine efficiency and reducing particulate matter (PM) emissions because of its stronger phase change process and conseq...

Understanding multi-stage HCCI combustion caused by thermal stratification and chemical three-stage auto-ignition

The Homogeneous Charge Compression Ignition (HCCI) concept shows great potential for improving engine efficiency and reducing pollutant emissions. However, the operation with this concept in Internal Combustion (IC) engines is still limited to low speed and load conditions, as excessive Pressure Rise Rates (PRR) are generated with its fast auto-ignition. To overcome this limitation, the use of moderate thermal and charge stratification has been promoted. This leads to multi-stage ignition, and thus a potentially acceptable PRR. Recently Sarathy et al. (2019), three-stage auto-ignition has been emphasized as a chemical phenomenon where the thermal runaway is inhibited during the main ignition event. The current paper demonstrates experimental evidence on this phenomenon observed during n-heptane and n-hexane auto-ignition at lean diluted conditions in a flat piston Rapid Compression Machine (RCM). Multi-stage ignition events caused by either chemical kinetics or by the well-known thermal stratification of this type of RCM are clearly identified and differentiated. The combination of these two factors seems to be a suitable solution to overcome PRR limitations.

Thermal efficiency improvement of super-lean burn spark ignition engine by stratified water insulation on piston top surface

In order to improve thermal efficiency of spark ignition engine under super-lean burn conditions (excess air ratio [Formula: see text]), thermal stratification technique by in-cylinder water injection toward piston surface (stratified water insulated combustion architecture), in which low temperature water vapor layer is formed on the surface, is proposed. From the water spray visualization using the optically accessible engine, injected water is distributed near the piston top surface at ignition timing and thermal stratification can be achieved in the case that water injection timing (SOIw) is set at earlier stage of a compression stroke. In addition, heat flux on the piston surface measured at the same time is reduced by water injection. The 0.5-L single-cylinder engine test at λ = 2.0 at a constant ignition timing also shows that water injection at earlier stage of a compression stroke makes it possible to mitigate knock without significant increase in combustion instability. On the other hand, part of water is distributed near the spark plug at ignition timing with the water injection at SOIw = −60 °ATDC, resulting in unstable combustion. In addition, the engine test at λ = 2.0 and water/fuel ratio(W/F) = 18% shows that knock mitigation by water injection enables spark advance and following combustion enhancement. As a result, combustion period becomes short and cooling loss decreases, followed by the 1.0-pt improvement of gross indicated thermal efficiency. Moreover, the engine can be operated at minimum spark advance for best torque by increasing W/F up to 35%. Finally, stratified water insulated combustion architecture concept is applied at λ = 1.9 with a higher compression ratio of 17, showing that water injection at SOIw = −120 °ATDC and W/F = 50% enables minimum spark advance for best torque operation, and remarkably high gross indicated that thermal efficiency of 52.63% can be achieved with a sufficiently low knock level and coefficient of variation of indicated mean effective pressure.