Browse Topic: Engine efficiency

Items (2,761)

Hybrid-Electric Powertrain Design for Enhanced Vehicle Performance

F-0081-2025-0369

5/20/2025

Electrification could improve full-size rotorcraft performance by reducing peak turbine power demand, reducing transmission system weight and complexity, and reducing operating costs. Integrating electric machines with mechanical powertrains requires careful consideration of the system-level weight and efficiency impacts. This paper presents an optimization framework for evaluating parallel hybrid powertrain configurations using Geometric Programming (GP). Both retrofit and clean-sheet vehicle designs are considered. The results show that high-speed electric motors integrated into a parallel hybrid configuration using batteries can reduce the sized gas turbine power, enabling more efficient engine operation at lower power levels. For retrofit designs, with a fixed vehicle gross weight, adding batteries and motors reduces usable fuel, decreasing mission capability. Clean-sheet designs offer additional flexibility to re-size the vehicle and rotor, resulting in energy savings for an equivalent design mission.

VanLandingham, Aaron, Hall, David, Smith, Edward, Bill, Robert

Tight

AIR12122024A (Current)12/12/2024

New Scoop

A-6 Aerospace Actuation, Control and Fluid Power Systems

A Numerical Study on the Effect of a Pre-Chamber Initiated Turbulent Jet on Main Chamber Combustion

2022-01-0469

3/29/2022

To elucidate the complex characteristics of pre-chamber combustion engines, the interaction of the hot gas jets initiated by an active narrow throated pre-chamber with lean premixed CH4/air in a heavy-duty engine was studied computationally. A twelve-hole KAUST proprietary pre-chamber geometry was investigated using CONVERGE software. The KAUST pre-chamber has an upper conical part with the spark plug, and fuel injector, followed by a straight narrow region called the throat and nozzles connecting the chambers. The simulations were run for an entire cycle, starting at the previous cycle's exhaust valve opening (EVO). The SAGE combustion model was used with the chemistry modeled using a reduced methane oxidation mechanism based on GRI Mech 3.0, which was validated against in-house OH chemiluminescence data from the optical engine experiments. Two different piston geometries, a flat piston geometry, and a more realistic bowl piston geometry were studied to understand the influence of jet on main chamber combustion. Varying the piston geometries results in different free jet times and hence main chamber combustion characteristics. Pre-chamber fuel ratio (PCFR) 6% of the total amount of fuel was investigated while keeping the global excess air ratios (λ) condition a constant value of 2.0. Both piston cases resulted in similar pre-chamber pressurization, with almost the same pre-chamber discharge and the equal pressure difference between pre-and main-chamber (ΔP) at the start of jet ejection. Different combustion behaviors were observed on analysis of the heat release rate in the main chamber. The importance of turbulence generated by the pre-chamber-initiated jets was further studied. It was observed that free jet time is a critical factor in developing turbulence in the main chamber. This increase in turbulence helps in increasing the burning velocity causing faster combustion. The influence of the jet-piston interaction is also analyzed as that determines the combustion behavior in the later CAD.

Sanal, Sangeeth, Echeverri Marquez, Manuel, Silva, Mickael, Cenker, Emre, Im, Hong G.

Test 123

SAE-PP-005182/8/2022

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Basile, Julia, Mutagaana, Festo

Continuously Variable Displacement Drive for Engines Part 2, Design, Analysis, and Test

SAE-PP-005162/8/2022

A new type of drive system has been designed, analyzed, patented, prototyped, and tested. The drive’s unique capabilities include the ability to vary the bottom dead center position to reduce the stroke, and simultaneously vary the top dead center position to achieve the desired compression ratio with one simple, low friction mechanism. The purpose of the concept is to reduce losses associated with operation at partial load as most engines spend a preponderance of their operating life at partial load. This paper covers the design and analysis, prototyping, and testing of the unit as an air compressor. Engine simulation of the unit configured as a gasoline engine showed a ~30% improvement in fuel economy on a 10-mode weighted cycle and is covered in SAE 2021-01-0442, “Continuously Variable Displacement Drive for Engines Part 1, Performance Simulation.”

Basile, Julia

Generating some more Tasks

SAE-PP-0049311/10/2021

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Kelly, Jason

48V Exhaust Gas Recirculation Pump: Reducing Carbon Dioxide with High-Efficiency Turbochargers without Increasing Engine-Out NOx

02-14-03-0024

8/23/2021

Regulations limiting GreenHouse Gases (GHG) from Heavy-Duty (HD) commercial vehicles in the United States (US) and European Union will phase in between the 2024 and 2030 model years. These mandates require efficiency improvements at both the engine and vehicle levels, with the most stringent reductions required in the heaviest vehicles used for long-haul applications. At the same time, a 90% reduction in oxides of nitrogen (NOx) will be required as part of new regulations from the California Air Resources Board. Any technologies applied to improve engine efficiency must therefore not come at the expense of increased NOx emissions. Research into advanced engine architectures and components has identified improved turbomachine efficiency as one of the largest potential contributors to engine efficiency improvement. However this comes at the cost of a reduced capability to drive high-pressure Exhaust Gas Recirculation (EGR). This study investigates the combination of a high-efficiency turbocharger and an electric EGR pump to allow improved engine fuel efficiency without the corresponding penalty to engine-out NOx. Results collected on a 13L 2019 model year engine on a dynamometer show the potential for a 3.5% reduction in engine Brake-Specific Fuel Consumption (BSFC) at engine operating conditions representative of highway cruise. Improvements at other engine operating conditions are also possible with careful matching of the turbocharger and EGR pump.

Johnson, Gustav, Bockstanz, Bradford, Bagal, Nilesh, Hopkins, Justin, Hughes, Doug, Playfoot, Ben

Regulated Intake Air Boosting and Engine Downspeeding as a Viable Solution for Performance Improvement and Emission Reduction of a Single-Cylinder Diesel Engine

03-15-02-0009

8/16/2021

The present work proposes a viable approach to develop single-cylinder diesel engines for the future by implementing regulated intake air boosting (RIAB) and engine downspeeding (ED) along with the well-established low compression ratio (LCR) approach. The investigations were conducted in a mass-production light-duty single-cylinder diesel engine initially equipped with a naturally aspirated (NA) intake system. By lowering the compression ratio (CR) and implementing the intake air boosting (IAB) using a belt-driven supercharger, the maximum brake mean effective pressure (BMEP) of the engine could be increased by 50%. More importantly, the improved performance could be achieved without violating the peak firing pressure (PFP) limits. However, a significant penalty was observed in the brake-specific fuel consumption (BSFC) at low-load operating points due to the additional power consumption of the IAB system. Hence, RIAB was implemented to optimize the boost pressure with respect to engine load to simultaneously reduce the BSFC and oxides of nitrogen (NOx) and soot emissions. Further, the increased full-load performance of the engine was leveraged to implement the ED approach that could reduce the operating speeds of the engine by 37.8%. It was observed that the benefits of downspeeding a supercharged engine are significantly high due to the simultaneous reduction of the frictional losses of the base engine and the power consumption of the supercharger. Overall, by combining the above concepts and the proven LCR approach, significant benefits could be achieved in fuel economy and exhaust emissions that are quantified for the regulatory Modified Indian Drive Cycle (MIDC) using a one-dimensional tool. The obtained results show a net reduction of 77.8% and 39.5% in the soot and NOx emissions, respectively. Moreover, a significant benefit of 14.8% could be achieved in the fuel economy. Thus the proposed approach can be used to develop single-cylinder diesel engines for the future to improve vehicle performance and comply with stringent emission regulations.

Vikraman, V., Krishnasamy, Anand, Ramesh, A.

workflow test

SAE-PP-003998/13/2021

workflow e2e test

SintzUSER, Jeneane

Transformational Technologies Reshaping Transportation - An Industry Perspective

SAE-PP-003372/26/2021

Freight trucking has always embraced continuous improvement although the general public may be largely unaware of the tremendous changes that have occurred to date in vehicle safety, efficiencies, emissions mitigation and asset utilization. Today’s freight industry is in the early stages of dramatic technological advances in areas such as connectivity, automation and electrification. Fleet and manufacturer perspective on these transformational technologies are universally supportive, driven both by economic and regulatory factors. The early stages of these technological revolutions are characterized by a multitude of competing concepts confusing choices, complicated by a significant number of competing vested interests obscuring objectivity, and clouded by billions of dollars of venture capital. The objective of this report is to provide unbiased insight into the freight industry’s thoughts on these transformational technologies.

Mutagaana, Festo, SintzUSER, Jeneane

A New Image De-hazing Method for Safety Critical ADAS Applications

SAE-PP-003122/19/2021

Driver safety and Advanced Driver Assistance Systems (ADAS) is gaining lot of importance these days. In some countries, there are strict regulations in place which mandate the use of certain ADAS features in automobiles. However, as the need for these safety critical systems increases, the challenges associated also increase. These challenges can arise due to technology, human factors or due to nature. In countries like India, where one can expect different weather conditions with changing geography, the associated challenges are mainly due to the natural factors like haze, fog, rain and smoke. This poses a challenging problem in terms of visibility for the drivers as well as in vision based ADAS; thereby, leading to many fatal road accidents. In this paper, a novel pre-processing technique, which addresses the interesting problem of enhancing the perceptual visibility of an image that is degraded by atmospheric haze, is proposed. The solution to this problem is presented by combining model (Beer Lambert model) based and non-model based technique of haze removal. The combined hybrid model picks the best haze free image from the series of non-hazy outputs, that are derived based on multiple scattering coefficients of the input hazy image. The idea here is to restore the true color of an image that is affected by the atmospheric haze. In comparison with the state of the art methods that are available in literature, the proposed method is shown to be capable of recovering better haze-free images both in terms of visual perception and quantitative evaluation. The proposed method promises better perceptual understandings and visibility restoration for vision based ADAS under hazy driving conditions.

Mutagaana, Festo, SintzUSER, Jeneane

7.0.102 - Prescriptive Modeling, Simulation and Performance Analysis of Mild Hybrid Vehicle and Component Optimization

SAE-PP-002782/4/2021

Reckoning today's environmental rules, legislative regulation and market requirements- the automotive industry of late has witnessed an increased vigor and enthusiasm by auto makers towards electrification of vehicles across all platforms in a bid to improve fuel economy and performance. Hybridization of a vehicle often involves the use of expensive high performance motors and large battery packs. However due to the challenges associated with the packaging of bulky battery and motor systems in existing drive train, mild hybrid systems have been preferred over strong or full hybrids especially in current production models as they don't entail any major change in architecture and the reduced battery size, both of which provide for easier packaging of components. In this paper the authors present a generic model of a mild hybrid vehicle that can be effectively used to simulate any vehicle, enabled with a mild hybrid system to predict with approximate certainty the improvement in performance parameters and optimize component size. Thus, assist in selection and sizing of motor, battery and the associated operation voltage, with minimal monetary expense and time consumption. Consequently, an optimal system configuration for the prototype build is arrived while resulting in significant cost and time savings.

Lname, Fname

6.0.117 - Definition of a Protocol of Automatic Identification and Notification of Road Accidents and Development of an Advanced eCall System

SAE-PP-002722/4/2021

The eNOTIFY project defined an algorithm which allows the vehicle to recognize when an accident has occurred and what kind of accident has taken place (frontal, side, roll-over or rear-end collision). The innovative aspects of this methodology are basically that, for each type of accident and for each class of vehicle, a maximum and minimum level of vehicle accelerations (linear or angular) are defined for the severe accident, slight accident and no accident scenarios. A direct application of this algorithm could be to include it in an on-board unit on vehicles, and use it in emergency call applications. eCall devices have been developed to automatically notify emergency services in the event of an accident, in which a fast and efficient rescue operation can significantly increase the chances of survival of the severely injured. In order to reduce response time and improve the efficiency of the medical and technical services, fast and accurate accident identification is required. This on-board algorithm makes it possible to identify the type and severity of the accident allowing emergency services to respond accordingly; and as such could contribute to saving lives.

Mutagaana, Festo

6.0.107 - A Unified Approach for Prediction and Control of Motorcycle Vibration Subjected to Engine Dynamic Force

SAE-PP-002632/4/2021

In this paper the approach to predict vibrations in motorcycles is presented. It can be divided mainly in two parts: prediction of engine forces using multi body dynamics (MBD) simulation and prediction of vibration response using FEA. Dynamic forces predicted at each engine mount through MBD simulation are used as input to FE analysis for vibration prediction. Single cylinder SI engine having primary balancer shaft is considered to develop this methodology. Flexibilities of important parts are considered for MBD simulation. Crankshaft ball bearing which is used in almost all two wheeler engine is modeled with 6×6 stiffness matrix. It provides coupling between radial, axial and tilting deflections of bearing and it also allows moment transfer from crankshaft to casing. This helps to predict realistic forces at each bearing and engine mounts. Distribution of primary and secondary forces at crank bearings and at different engine mounts is studied. Forces predicted from MBD simulation at each engine mounts are applied to full vehicle FE model. Forced response is predicted at each TSP and compared with test response at same point. It was found that predicted response was in well agreement with test response. Based on understanding of distribution of forces it is decided to increase mount stiffness of the support experiencing more force. This in turn helped to reduce vibration at TSP. This approach is effective to predict vibrations in early design stage to reduce development cost and time.

Mutagaana, Festo

6.0.102 - FeSn

SAE-PP-002582/4/2021

The aim of this study is to develop the simple approach to produce iron-tin (Fe-Sn) intermetallic compound for EV battery anode materials. Intermetallic FeSn2 compound was synthesized by two step method. Mechanical alloying of Fe and Sn element powders with equal atomic ratio was performed for 25 h. The mechanically alloyed powders compacts were processed via liquid phase sintering, in which the powders compacts were heated at different temperatures and for 10 min. The experimental materials were characterized by X-ray diffraction, scanning electron microscopy and thermal analysis techniques. The FeSn2 compound was formed during liquid phase sintering. However, the reaction between Fe and Sn was incomplete under the investigated sintering time of 10 min.

Mutagaana, Festo

Near-TDC flow field analysis in a high-tumble production SI engine using endoscopic high-speed Particle Image Velocimetry (eHS-PIV)

SAE-PP-002512/3/2021

The latest generation spark-ignition (SI) engines implement high tumble flow design to achieve unprecedented high brake thermal efficiency of over 40%, which will continue to play an important role in both conventional and electrified future vehicles. To maximise the potential of high-tumble SI engines, there is a clear need for in-cylinder flow and flame analysis conducted timely in a realistic environment. For the first time, this study meets this need by performing innovative endoscopic imaging of flow fields and flame inside the cylinder of a selected production engine using a particle image velocimetry (PIV) laser and high-speed camera system operated at 35 kHz. Through this timeresolved, two-dimensional measurement of the realistic in-cylinder phenomenon, many new findings have been achieved. Regarding the tumble vortex, its centre is seen more shifted to the exhaust valve side, which is related to an asymmetric, “surging” flow structure formed during the upward motion of the piston in the compression stroke. When the piston approaches towards the top dead centre, the tumble centre is not clearly defined anymore, but a new lateral exhaust-to-intake flow forms as the surging flow bounces back off the exhaust valve side of the pent-roof. This wallguided “bounce-back” flow does not form when the intake valve closure is retarded for the realisation of Atkinson Cycle and thus the surging flow is reduced and peaks at later timing. The new in-cylinder flow structures observed from the high-tumble engine directly impact the flame development. From the high-speed natural combustion luminosity imaging performed using the same camera endoscope, the flame centroid is found to shift towards the intake valve side, which is consistent with the bounce-back flow direction at the advanced intake valve closure timing.

Anthony, Lindsay

6.0.113 - Measuring Smoke Emissions from Different Generations Diesel Passenger Cars in Antwerp-Belgium During Winter and Spring

SAE-PP-002442/3/2021

More than 600 passenger cars were measured during winter and spring at the end of 2012 beginning 2013 in Antwerp Belgium in order to determine the effect of mileage and year of first registration on smoke emissions or smoke opacity from diesel light duty vehicles. All measurements were contacted in two different campuses of the University of Antwerp and under different ambient conditions. Various parameters such as ambient temperature, ambient humidity, car age, number of passengers in each cars, time of measurement etc. were taken into account and presented in this paper. All findings from these set of measurements were split into two big categories, those cars with less than 150,000km on the clock and the second one with those cars with higher number of mileage. The effect of ambient temperature but also the mileage on smoke opacity will be presented and discussed in more details. Smoke emissions are dependent also on ambient humidity and in this study will be considered the important role that humidity plays in total smoke opacity from various diesel engines. Finally the effect of mileage on smoke opacity is something that will be also examined and discussed intensively. Last but not least, a comparison between two similar cars equipped with the same engine in terms of capacity but fitted with standard and tuned electronic control unit (ECU) respectively was done and interesting findings will be shown in this work.

Mutagaana, Festo

The Effect of Engine Speed, Exhaust Gas Recirculation (EGR) and Compression Ratio on Isobaric Combustion

SAE-PP-002322/3/2021

The present study evaluates the effect of engine speed, exhaust gas recirculation (EGR) and compression ratio on conventional diesel combustion (CDC) and two isobaric combustion cases, by utilizing multiple injection strategies. The experiments were conducted in a Volvo D13C500 singlecylinder, heavy-duty engine, fuelled with standard EU diesel fuel. The engine was operated at three different speed of 1200, 1500 and 1800 revolutions per minute (rpm). For each engine speed and combustion cases, EGR rate was varied from 0 ~ 40%. The low-pressure isobaric combustion (IsoL) and high-pressure isobaric combustion (IsoH) were maintained at peak cylinder pressure (PCP) of 50 and 68 bar, respectively, which was representative of the peak motoring pressure (PMP) and PCP of conventional diesel combustion. This was possible by adjusting the intake air pressure to 1.7 bar and 2.3 bar – absolute for IsoL and IsoH, respectively at 1200 rpm. At higher engine speed, the intake air pressure was further increased to maintain top-dead center (TDC) pressure. Irrespective of engine speed and EGR rates, it was found that IsoH has similar or higher gross indicated efficiency than CDC with the lowest efficiency for IsoL combustion. The heat transfer losses were lower while the exhaust losses were higher for isobaric cases, compared to CDC. The heat transfer losses were further reduced due to limited time availability at higher engine speed with a penalty in higher exhaust losses for all combustion cases. This additional exhaust energy would not be totally lost as it can be converted into useful work using expander cylinder of the double compression expansion engine (DCEE) concept. At given engine speed, higher EGR rates resulted in higher carbon monoxide (CO)/unburnt hydrocarbon (UHC)/soot emissions with lower nitrogen oxides (NOx) emissions. However, with increased engine speed, CO and UHC emissions were highly unchanged. A typical soot-NOx trade-off characteristic can be seen with increased soot and reduced NOx emissions, largely due to reduced charge premixing time at higher engine speed. From the compression ratio comparison results, it was found that a lower compression ratio resulted in reduced gross indicated efficiency and increased exhaust losses. Compared to the higher compression ratio, the lower compression ratio also led to lower heat transfer losses due to reduced combustion temperature. Besides, the NOx emissions were reduced with increased soot concentration at the lower compression ratio.

Anthony, Lindsay

053 - System Optimization for a 2-Stroke Diesel Engine with a Turbo Super Configuration Supporting Fuel Economy Improvement of Next Generation Engines

SAE-PP-001911/30/2021

The objective of this paper is to present the results of the GT Power calibration with engine test results of the air loop system technology down selection described in the SAE Paper No. 2012-01-0831. Two specific boosting systems were identified as the preferred path forward: (1) Super-turbo with two speed Roots type supercharger, (2) Super-turbo with centrifugal mechanical compressor and CVT transmission both downstream a Fixed Geometry Turbine. The initial performance validation of the boosting hardware in the gas stand and the calibration of the GT Power model developed is described. The calibration leverages data coming from the tests on a 2 cylinder 2-stroke 0.73L diesel engine. The initial flow bench results suggested the need for a revision of the turbo matching due to the big gap in performance between predicted maps and real data. This activity was performed using Honeywell turbocharger solutions spacing from fixed geometry waste gate to variable nozzle turbo (VNT). New simulations results recommend VNT as it offers a higher potential to reduce BSFC with increase power and low end torque output than the original matching. For the high pressure stage the mechanical Roots type and the CVT superchargers have been assessed and the latter one has been identified having higher power adsorption than traditional positive displacement supercharger. This has allowed the supplier to work on an optimization of the units. Ultimately the VNT with CVT supercharger has been assessed on engine and it allowed confirming the validity and accuracy of the GT Power model after its calibration.

Mutagaana, Festo

021 - Development of a 0D Model Starting from Different RANS CFD Tumble Flow Fields in Order to Predict the Turbulence Evolution at Ignition Timing

SAE-PP-001501/25/2021

aster combustion and lower cycle-to-cycle variability are mandatory tasks for naturally aspirated engines to reduce emission levels and to increase engine efficiency. The promotion of a stable and coherent tumble structure is considered as one of the best way to promote the in-cylinder turbulence and therefore the combustion velocity. During the compression stroke the tumble vortex is deformed, accelerated and its breakdown in smaller eddies leads to the turbulence enhancement process. The prediction of the final level of turbulence for a particular engine operating point is crucial during the engine design process because it represents a practical comparative means for different engine solutions. The tumble ratio parameter value represents a first step toward the evaluation of the turbulence level at ignition time, but it has an intrinsic limit. The tumble ratio parameter represents the value of the angular velocity of a single macro vortex, while the flow-field is often characterized by multiple vortexes, sometimes some rotating and some counter-rotating. The idea at the basis of the paper is: To develop a quasi-predictive 0D model for defining the final mean level of the turbulence at the ignition time. The model is fed by the curtain intake valve mass flow rate and the intake valve lift trend. In order to validate the 0D model the results were compared versus 3D CFD results. To extract from a 3D CFD flow field at IVC the type and the number of the vortexes. The 3D CFD RANS simulations were performed by AVL Fire code v. 2010. To demonstrate through some 3D CFD results that the flow field structure was a function only of the engine type and the load condition. Finally the flow field structure could be used in the 0D model on varying the engine speeds as a means of improvement of the model prediction capability.

Mutagaana, Festo

Aerospace Auxiliary Power Sources

AIR744D (Current)

11/19/2020

This SAE Aerospace Information Report (AIR) is a review of the general characteristics of power sources that may be used to provide secondary, auxiliary, or emergency power for use in aircraft, space vehicles, missiles, remotely piloted vehicles, air cushion vehicles, surface effect ships, or other vehicles in which aerospace technology is used. The information contained herein is intended for use in the selection of the power source most appropriate to the needs of a particular vehicle or system. The information may also be used in the preparation of a power source specification. Considerations for use in making a trade study and an evaluation of the several power sources are included. More detailed information relating to specific power sources is available in other SAE Aerospace Information Reports or in Aerospace Recommended Practices.

A-6C4 Power Sources Committee

The Effect of Engine Speed, Exhaust Gas Recirculation, and Compression Ratio on Isobaric Combustion

03-13-05-0038

8/14/2020

The present study evaluates the effect of engine speed, exhaust gas recirculation (EGR), and compression ratio on conventional diesel combustion (CDC) and two isobaric combustion cases, by utilizing multiple injection strategies. The experiments were conducted in a Volvo D13C500 single-cylinder, heavy-duty engine, fuelled with standard European Union (EU) diesel fuel. The engine was operated at three different speeds of 1200, 1500, and 1800 revolutions per minute (rpm). For each engine speed and combustion cases, the EGR rate was varied from 0% to 40%. The low-pressure isobaric combustion (IsoL) and high-pressure isobaric combustion (IsoH) were maintained at peak cylinder pressure (PCP) of 50 and 68 bar, respectively, which was representative of the peak motoring pressure (PMP) and PCP of CDC. This was possible by adjusting the intake air pressure to 1.7 and 2.3 bar—absolute for IsoL and IsoH, respectively, at 1200 rpm. At a higher engine speed, the intake air pressure was further increased to maintain top dead center (TDC) pressure. Irrespective of engine speed and EGR rates, it was found that IsoH has similar or higher gross indicated efficiency than CDC with the lowest efficiency for IsoL. The heat transfer losses were lower while the exhaust losses were higher for isobaric cases, compared to CDC. The heat transfer losses were further reduced due to limited time availability at higher engine speeds with a penalty in higher exhaust losses for all combustion cases. This additional exhaust energy would not be totally lost as it can be converted into useful work using an expander cylinder of the double compression expansion engine (DCEE) concept. At a given engine speed, higher EGR rates resulted in higher carbon monoxide (CO)/unburnt hydrocarbon (UHC)/soot emissions with lower nitrogen oxides (NOx) emissions. However, with increased engine speed, CO and UHC emissions were highly unchanged. A typical soot-NOx trade-off characteristic can be seen with increased soot and reduced NOx emissions, largely due to reduced charge premixing time at higher engine speed. From the compression ratio comparison results, it was found that a lower compression ratio resulted in reduced gross indicated efficiency and increased exhaust losses. Compared to the higher compression ratio, the lower compression ratio also led to lower heat transfer losses due to reduced combustion temperature. Besides, the NOx emissions were reduced with increased soot concentration at the lower compression ratio.

Goyal, Harsh, Dyuisenakhmetov, Aibolat, Houidi, Moez Ben, Johansson, Bengt, Badra, Jihad, Cenker, Emre, Chang, Junseok

Further Experiments on the Effect of Bulk In-Cylinder Temperature in the Pressurized Motoring Setup Using Argon Mixtures

2020-01-10634/14/2020

Mechanical friction and heat transfer in internal combustion engines have long been studied through both experimental and numerical simulation. This publication presents a continuation study on a Pressurized Motoring setup, which was presented in SAE paper 2018-01-0121 and found to offer robust measurements at relatively low investment and running cost. Apart from the limitation that the peak in-cylinder pressure occurs around 1 DegCA BTDC, the pressurized motoring method is often criticized on the fact that the gas temperatures in motoring are much lower than that in fired engines, hence might reflect in a different FMEP measurement. In the work presented in SAE paper 2019-01-0930, Argon was used as the pressurization gas due to its high ratio of specific heats. This allowed to achieve higher peak in-cylinder temperatures which close further the gap between fired and motored mechanical friction tests. In 2019-24-0141, Argon was mixed in different proportions with Air to synthesize gases with different ratios of specific heats in the aim of observing any abrupt transitions in the FMEP with different peak in-cylinder temperatures. In this publication, a higher loading test matrix to that published in 2019-24-0141 is presented, with an engine speed ranging from 1400 rpm to 3000 rpm and ratios of specific heats varying from that of Air (γ = 1.4) to that of Argon (γ = 1.67). The peak in-cylinder pressure was kept at a constant 103 bar. Results obtained in this work strengthen further the observations made in 2019-24-0141; where the measured FMEP is found to be insensitive to the different peak in-cylinder temperatures. In this study, a fast-response thermocouple of the eroding type was also fitted in the combustion chamber and gas-wall interface temperature histories were recorded. The transient heat flux was also computed through a spectral analysis and reported in this publication.

Caruana, Carl, Farrugia, Mario, Sammut, Gilbert, Pipitone, Emiliano

The Effects of Thick Thermal Barrier Coatings on Low-Temperature Combustion

2020-01-02754/14/2020

An experimental study was conducted on a Ricardo Hydra single-cylinder light-duty diesel research engine. Start of Injection (SOI) timing sweeps from -350 deg aTDC to -210 deg aTDC were performed on a total number of five pistons including two baseline metal pistons and three coated pistons to investigate the effects of thick thermal barrier coatings (TBCs) on the efficiency and emissions of low-temperature combustion (LTC). A fuel with a high latent heat of vaporization, wet ethanol, was chosen to eliminate the undesired effects of thick TBCs on volumetric efficiency. Additionally, the higher surface temperatures of the TBCs can be used to help vaporize the high heat of vaporization fuel and avoid excessive wall wetting. A specialized injector with a 60° included angle was used to target the fuel spray at the surface of the coated piston. Throughout the experiments, the equivalence ratio, ϕ, was maintained constant at 0.4; the combustion phasing was consistently matched at 6.8 ± 0.4 deg aTDC. It can be concluded that the thick TBC cases achieved 1 to 2 percentage points improvement in combustion efficiency, and generally, a ~2 percentage points increase in indicated engine efficiency. It is also noticed that applying a dense top sealing layer to the TBC further improves the UHC emissions compared to the TBC coated piston with an unsealed surface. From the heat release analysis, it can be concluded that the TBCs have no significant impact on the heat release process and knock intensity while matching the combustion phasing; however, it reduces the intake temperature requirement by up to 20 K. The exhaust gas temperatures were expected to increase for the TBC cases, but the expected increase in exhaust temperature was not conclusive from the results observed in this study.

Yan, Ziming, Gainey, Brian, Gohn, James, Hariharan, Deivanayagam, Saputo, John, Schmidt, Carl, Caliari, Felipe, Sampath, Sanjay, Lawler, Benjamin

An Analytical Approach for Calculating Instantaneous Multilayer-Coated Wall Surface Temperature in an Engine

2020-01-01604/14/2020

Thermal swing coatings that have low volumetric heat capacity and low thermal conductivity are attractive because they have the potential to significantly reduce heat transfer to the combustion chamber walls. This paper presents an analytical method for determining the exact solution of the time-resolved wall temperature during the engine cycle for any number of coating layers and properties using the Laplace transformed heat diffusion equation. The method relies only on material properties and the past heat flux history, and represents the exact solution of the heat diffusion equation. The analytical nature of the solution enables fast computation and, therefore, application to system-level optimization calculations. The model relies on an assumption of one-dimensional heat flow, and constant material properties. The major advantage of this approach compared to the standard finite difference approach, wherein the wall is finely discretized, is that there is no approximation and the accuracy is guaranteed, i.e., it does not depend on nodal density. Results are presented for both a quasi-steady operating condition and for an engine transient event. In the latter case a 200-fold reduction in computation time relative to a finite difference code was realized.

Koutsakis, G., Ghandhi, J.B.

CO2 Neutral Heavy-Duty Engine Concept with RCCI Combustion Using Seaweed-based Fuels

2020-01-0808

4/14/2020

This paper focusses on the application of bioalcohols (ethanol and butanol) derived from seaweed in Heavy-Duty (HD) Compression Ignition (CI) combustion engines. Seaweed-based fuels do not claim land and are not in competition with the food chain. Currently, the application of high octane bioalcohols is limited to Spark Ignition (SI) engines. The Reactivity Controlled Compression Ignition (RCCI) combustion concept allows the use of these low carbon fuels in CI engines which have higher efficiencies associated with them than SI engines. This contributes to the reduction of tailpipe CO2 emissions as required by (future) legislation and reducing fuel consumption, i.e. Total-Cost-of-Ownership (TCO). Furthermore, it opens the HD transport market for these low carbon bioalcohol fuels from a novel sustainable biomass source. In this paper, both the production of seaweed-based fuels and the application of these fuels in CI engines is discussed. Ethanol and butanol are considered as the most viable fuels derived from seaweed. The potential of these fuels has been evaluated for the dual-fuel RCCI mode regarding efficiency and NOx emissions. The operating conditions that have been varied are mainly the fuel blend ratio (BR), fuel injection timing, and EGR rate on both a HD single-cylinder and on a HD multi-cylinder engine. The results for E85/diesel-RCCI demonstrate that CI engine-like efficiencies are feasible. The gross Indicated Thermal Efficiency (ITE) reaches up to 52% and 46.5% using E85 in a single-cylinder and a multi-cylinder engine, respectively. The first results using biomass based butanol show greater difficulty in realizing targeted efficiencies on the multi-cylinder engine due to the higher fuel reactivity and higher boiling temperature than ethanol. The gross ITE reaches up to 51.6% and 38.5% using butanol in a single-cylinder and a multi-cylinder engine, respectively. The demonstrated potential of seaweed-based fuels is an important driver for upscaling the production process of these fuels. Furthermore, future development activities will focus on improving the brake thermal efficiency of the RCCI engine running on seaweed-based fuels. Improving the low reactivity fuel-air mixture preparation will be key to achieve this.

Seykens, Xander, Bekdemir, Cemil, Han, Jinlin, Willems, Robbert, Van Hal, Jaap

Numerical Investigation of the Combustion Kinetics of Partially Premixed Combustion (PPC) Fueled with Primary Reference Fuel

2020-01-0554

4/14/2020

This work numerically investigates the detailed combustion kinetics of partially premixed combustion (PPC) in a diesel engine under three different premixed ratio fuel conditions. A reduced Primary Reference Fuel (PRF) chemical kinetics mechanism was coupled with CONVERGE-SAGE CFD model to predict PPC combustion under various operating conditions. The experimental results showed that the increase of premixed ratio (PR) fuel resulted in advanced combustion phasing. To provide insight into the effects of PR on ignition delay time and key reaction pathways, a post-process tool was used. The ignition delay time is related to the formation of hydroxyl (OH). Thus, the validated Converge CFD code with the PRF chemistry and the post-process tool was applied to investigate how PR change the formation of OH during the low-to high-temperature reaction transition. The reaction pathway analyses of the formations of OH before ignition time were investigated. It was found that in the case of PR0%, the second isomerization from C7H14OOH2-4O2 to NC7KET24 and the decomposition of NC7KET24 contributed 27.6% and 46.46% of OH formation respectively. The contribution of AC8H16OOH-B to the formation of OH was just 12.13%. It can be concluded that the low temperature oxidation reactions of n-heptane were key steps in producing OH. While in the cases of PR30% and PR50%, because of the higher in-cylinder temperature, most of OH derived from the decomposition reaction of H2O2 that contributed 54.47% and 54.63% of OH formation respectively. Besides, in the PR30% and PR50%, the oxidation reactions of IC4H7 contributed 31.95% and 33.84% of OH formation respectively, and the oxidation reaction of IC4H6OH contributed 19.08% and 22.22% of OH formation respectively, which indicated that the oxidation of iso-octane also contributed to the production of OH. In addition, the distributions of mass fraction, production rate and representative creation reaction (RCR) of OH showed that in the case of PR30% and PR50%, the formation of OH outside the spray periphery were dominated by the reactions R394 (H2O2 (+ M) <=> 2 OH (+ M)), while that in the spray periphery were predominantly controlled by the reaction R21 (NC7KET24 => NC3H7CHO + CH3COCH2 + OH) and R125 (IC4H6OH + HO2 <=> CH2CCH2OH + CH2O + OH). Premixed fuel from port injection changed the formation pathway of OH during the oxidation of direct injection fuel through the reaction R125.

Zhao, Yuanyuan, Wang, Hu, Liu, Xinlei, Liu, Daojian, Chenchen, Wang, Zhu, Hongyan, Zheng, Zunqing, Yao, Mingfa

Development of Dual Fuel Engine Fueled with Used Cooking Oil Biodiesel and Ethanol-an Experimental Study on Performance and Combustion Characteristics

2020-01-0803

4/14/2020

This paper investigates the performance and combustion characteristics of a compression ignition engine (CI engine) fueled with Used Cooking Oil Biodiesel (UCOB) and ethanol in dual fuel mode. In this study, UCOB was injected as the main fuel through a conventional mechanical fuel injection system. Various mass flow rates of ethanol were inducted as primary fuel through the engine intake manifold using a separate fuel injection system. Mass flow rates of ethanol were metered by an electronic control circuit. The engine test was conducted under different load conditions from no load to full load in a fully instrumented direct injection, water-cooled compression ignition engine. The results indicated that the dual fuel engine produced higher brake thermal efficiency, cylinder pressure, heat release rate with lower specific fuel consumption at a higher load condition. However, it was found that combustion characteristics improved marginally at the lower load conditions.

Velmurugan, Ramanathan, Mayakrishnan, Jaikumar, Palanimuthu, Vijayabalan, Nandagopal, Sasikumar, Elumalai, Sangeethkumar, Anaimuthu, Shridhar, Busireddy, Vamshidhar