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Technical Paper

Parametric Investigations on Premixed Charged Compression Ignition in a Small Bore Light Duty Diesel Engine

2020-10-30
2020-32-2300
Achieving stable combustion without misfire and knocking is challenging in premixed charge compression ignition (PCCI) especially in small bore, air cooled diesel engines owing to lower power output and inefficient cooling system. In the present study, a single cylinder, air cooled diesel engine used for agricultural water pumping applications is modified to run in PCCI by replacing an existing mechanical fuel injection system with a flexible common rail direct injection system. An advanced start of fuel injection (SOI) and exhaust gas recirculation (EGR) are required to achieve PCCI in the test engine. Parametric investigations on SOI, EGR and fuel injection pressure are carried out to identify optimum parameters for achieving maximum brake thermal efficiency. An SOI sweep of 12 to 50 deg. CA bTDC is done and for each SOI, EGR is varied from 0 to 50% to identify maximum efficiency points. It was found that EGR helps in extending the load range from 20 to 40% of rated load.
Technical Paper

Study on the Effect of Air Density on the Performance of HCCI Engine Using Acetylene Gas as Fuel

2020-10-30
2020-32-2301
Owing to the combined merits of Spark ignition (SI) and compression ignition (CI) engines, homogeneous charge compression ignition (HCCI) engine technology has been receiving a greater attention in the last three decades. HCCI is a promising concept for combustion engines to reduce both emissions and fuel consumption. Utilization of different alternative fuels for HCCI engines is yet to be explored more. In this investigation, an attempt was made to use acetylene as a fuel in an HCCI engine. For this purpose, a single cylinder, four stroke, air-cooled CI engine was converted into HCCI mode. Acetylene was inducted into the intake manifold by using manifold injection technique. Air at different densities was supplied to the HCCI engine. The effects of varying air density on the performance and emission characteristics of the HCCI engine were assessed and the results are presented in this paper
Technical Paper

CFD Simulation Methodology for a Rotary Steam Expansion Piston Engine

2020-10-30
2020-32-2303
In industrial processes, combustion engines and co-generation plants, large amounts of waste heat are generated, which are often lost to the environment. The conversion of this thermal energy into mechanical work and ultimately into electrical power promises a significant improvement in energy utilization, the efficiency of the overall system and, consequently, cost-effectiveness. Therefore, the use of a Rankine Cycle is a well-established technical process. A recent research project investigates a novel expansion machine to be integrated into an RC-process to convert the heat energy into mechanical work. Primarily, the present work deals with the fluid dynamic simulation of this expander, which is based on the principle of a rotary piston engine. The aim is to develop, analyze and optimize the process and the corresponding components. Hence, a CFD model has to be built up, which should correspond as closely as possible to the requirements and geometries of the physical engine.
Technical Paper

Wall Heat Flux on Impinging Diesel Spray Flame: Effect of Hole Size and Rail Pressure under Similar Injection Rate Condition

2020-10-30
2020-32-2313
The fuel economy of recent small size DI diesel engines has become more and more efficient. However, heat loss is still one of the major factors contributing to a substantial amount of energy loss in engines. In order to a full understanding of the heat loss mechanism from combustion gas to cylinder wall, the effect of hole size and rail pressure under similar injection rate conditions on transient heat flux to the wall were investigated. Using a constant volume vessel with a fixed impingement wall, the study measured the surface heat flux of the wall at the locations of spray flame impingement using three thin-film thermocouple heat-flux sensors. The results showed that the characteristic of local heat flux and soot distribution was almost similar by controlling similar injection rate except for the small nozzle hole size with increasing injection pressure.
Technical Paper

Storage of Low Level Ethanol Blends in Small Engines

2020-10-30
2020-32-2319
This study examined the effects of storing gasoline (E0) and low level ethanol blends (E10, E15, E20) in small engines over a 12 month period. Many variables were monitored or controlled in order to determine if ethanol blended fuels affected small engines during storage. A sample size of 64 engines was used to reduce the effects of normal engine to engine performance variations and analyze trends with the different fuel blends. For the study, 32 handheld 2-stroke engines with a cube carburetor (leaf blowers) and 32 non-handheld 4-stroke consumer grade small engines with a float carburetor (gensets) were tested. These engines were selected to represent many different types of equipment on the market and for ease of loading during the study. The engines were measured after initial purchase, after 6 months of storage, and after 12 months of storage to check for changes.
Technical Paper

Improvement of Quasi-Steady State Heat Transfer Model for Intake System of IC Engines with Considering Backflow Gas Effect Using 1-D Engine Simulation

2020-10-30
2020-32-2315
For improving the thermal efficiency and the reduction of hazardous gas emission from IC engines, it is crucial to model the heat transfer phenomenon starting from the intake system and predict the intake air’s mass and temperature as precise as possible. Previously the authors developed an empirical equation based on an experimental setup of an intake port model of an ICE in order to be implemented into the engine control unit and numerical simulation software for heat transfer calculations. The authors developed an empirical equation based on the conventional Colburn analogy with the addition of Graetz and Strouhal numbers. Introduced dimensionless numbers were used to characterize the entrance region, and intermittent flow effects, respectively.
Technical Paper

Experimental Analysis on the Effects of Passive Prechambers on a Small 2-Stroke Low-Pressure Direct Injection (LPDI) Engine

2020-10-30
2020-32-2305
Two-stroke (2S) engines still play a key role in the global internal combustion engine (ICE) market when high power density, low production costs, and limited size and weight are required. However, they suffer from low efficiency and high levels of pollutant emissions, both linked to the short circuit of fuel and lubricating oil. Low- and high-pressure direct injection systems have proved to be effective in the reduction of fuel short circuiting, thus decreasing unburnt hydrocarbons and improving engine efficiency. However, the narrow time window available for fuel to be injected and homogenized with air, limited to few crank-angles, leads to insufficiently homogenized fuel-air mixtures and, as a consequence, to incomplete combustions. The use of prechambers can be a well-suited solution to avoid these issues.
Technical Paper

Two-Stroke Engine Mapping with Aerospace Testing Standard AS6971

2020-10-30
2020-32-2304
Small two-stroke engine performance reports between manufacturers and third party tests have unexplained discrepancies. The impact of different testing conditions on performance metrics provides reason for a universally accepted engine testing standard that applies specifically for engines used in Unmanned Aerial Vehicles (UAVs). The Society of Automotive Engineers (SAE) has proposed an aerospace engine testing standard, AS6971, as a solution to engine testing discrepancies. The work presented here is the first implementation of the AS6971 draft standard to a port fuel injected 60.5 cc two-stroke spark ignited engine as feedback to the SAE standards. The engine was tested across 2000 RPM - 5000 RPM with settings that maximized torque output and compared to the manufacturer's performance results. The difference in these results further demonstrate the need for an accepted testing standard between both manufacturers and third party engine testing groups.
Technical Paper

Improvement of Fuel Consumption for SI Engines by Combing with Glow Plug Heated Sub-chamber and Lean Burn

2020-10-30
2020-32-2310
Lean burn gasoline engines can achieve noteworthy fuel consumption and power output. However, when the mixture becomes lean, the ignition delay increases, and the flame propagation speed becomes slow, which lead to increase the combustion fluctuation. The glow plug is usually used to solve the cold start problem in diesel engines, where the compression temperature might not be high enough to ensure the proper ignition of the injected fuel, resulting in instability combustion and increased exhaust emissions. Based on this point, the present study intends to install a glow plug to the sub-chamber. Experiments were conducted on a modified single cylinder four-stroke CI engine (YANMAR TF120V) to operate as SI engine with a higher compression ratio compared to the conventional SI engines, 15.1:1. The engine is operated at a constant speed of 1000 rpm for different equivalence ratios with different voltage of glow plug which creates the temperature variation inside the sub-chamber.
Technical Paper

Numerical study on Premixed Charge Compression Ignition(PCCI) combustion for down-sized Diesel engine using CONVERGE

2020-10-30
2020-32-2308
The growing EV market and tougher EURO VI regulations require to further reduce the presence of diesel engines. However, diesel engines still have the advantages in high performance and high thermal efficiency, while It produces NOx and PM. Therefore, diesel engines should recognize the need for change. It is important to improve and practicalize innovative combustion technologies that can improve fuel efficiency without losing power in consideration of emission regulations. In that point view, the new combustion technology have been studied such as Premixed Charge Compression Ignition(PCCI) . This combustion technology can reduce both NOx and PM emissions through longer mixing time and Low Temperature Combustion(LTC) by applying advanced injection than conventional diesel combustion, In this study, numerical analysis for PCCI engine is performed to optimize injection angles that can reduce wall wetting, increase fuel efficiency and reduce emissions.
Technical Paper

Investigations on NOx and Smoke Emissions Reduction Potential through Diesel-Water Emulsion and Water Fumigation in a Small Bore Diesel Engine

2020-10-30
2020-32-2312
In the present work, a relative comparison of addition of water to diesel through emulsion and fumigation methods is explored for reducing oxides of nitrogen (NOx) and smoke emissions in a production small bore diesel engine. The water to diesel ratio was kept the same in both the methods at a lower concentration of 3% by mass to avoid any adverse effects on the engine system components. The experiments were conducted at a rated engine speed of 1500 rpm under varying load conditions. A stable water-diesel emulsion was prepared using a combination of equal proportions (1:1 by volume) of Span 80 and Tween 80. The mixture of Span 80 in diesel and Tween 80 in water was homogenized using an IKA Ultra Turrax homogenizer with tip stator diameter 18mm at 5000 rpm for 2 minutes. The water-in-diesel emulsions thus formulated were kinetically stable and appeared translucent. No phase separation was observed on storage for approximately 105 days.
Technical Paper

Lubricating Oil Droplets from Piston Crown on Abnormal Combustion in Supercharged SI Engine

2020-10-30
2020-32-2302
In recent years, the supercharged spark ignition engine (SI engine) is spread out in the field of passenger vehicle. However, it has a problem of abnormal combustion which is called Low Speed Pre-ignition (LSPI). It is cleared gradually that the character of lubricating oil effects on LSPI behavior. The lubricating oil which has a tolerance for LSPI has been introduced already in the market nowadays. However, cause and mechanism of LSPI occurrence does not clear sufficiently. In previous conference SETC 2018, it was reported that the peculiar behavior of LSPI corresponded with behavior of lubricating oil from piston crown. This paper focuses on frequency of lubricating oil scattering from piston crown.
Technical Paper

A Concept Investigation Simulation Model on Hybrid Powertrains for Handheld Tools

2020-10-30
2020-32-2316
Amid the increasing demand for higher efficiency in combustion driven handheld tools, the recent developments in electric machine technology together with the already existing benefits of small combustion engines for these applications favor the investigation of potential advantages in hybrid powertrain tools. This concept-design study aims to use a fully parametric, system-level simulation model with exchangeable blocks, created with a power-loss approach in Matlab and Simulink, in order to examine the potential of different hybrid configurations for different tool load cycles. After the model introduction, the results of numerous simulations for 36 to 100 cc engine displacement will be presented and compared in terms of overall system efficiency and overall powertrain size. The different optimum hybrid configurations can show a reduction of up to 30 % in system’s brake specific fuel consumption compared to the baseline combustion engine driven model.
Technical Paper

Autoignition of a Lubricating Oil Droplet with Fuel Ingredients on Abnormal Combustion of Supercharged SI Engine

2020-10-30
2020-32-2318
The supercharged spark ignition engine (SI engine) has a problem of abnormal combustion. It is called Low Speed Pre-ignition (LSPI). The lubricating oil which has a tolerance for LSPI has been introduced already in automobile market nowadays. However, cause and mechanism of LSPI does not clear sufficiently. It has been reported that the peculiar behavior of LSPI corresponded with behavior of lubricating oil from piston crown. This paper focuses on effect of fuel ingredients on autoignition of a lubricating oil droplet about LSPI. On the ignition source point of view, it is important to clear the mechanism of a lubricating oil droplet autoignition in cylinder. This paper will be tried to clear its mechanism fundamentally by using of electric furnace which is heated an oil droplet. As a result, the activation energy E is found for quantitative evaluation of LSPI.
Technical Paper

Experimental Investigations on Evaporation Characteristics of Fuels for Low Temperature Combustion Engine Application

2020-10-30
2020-32-2317
The combustion and emission formation in the advanced low temperature combustion (LTC) engine strategies are highly sensitive to fuel molecular composition and properties. Ignition timing in LTC is primarily controlled by fuel chemical kinetics and thus, tailoring of fuel properties is required to address its limitations in-terms of lack of control on ignition timing and narrow operating load range. Utilizing fuel blends and additives such as nanoparticles are one of the promising approaches to achieve targeted fuel property. An improved understanding of fundamental processes including fuel evaporation is required owing to its role in fuel-air mixing and thereby emission formation in LTC. In the present work, evaporation characteristics of blends of commercial fuels, viz. gasoline, diesel and alternative fuels, viz. ethanol and butanol are investigated. Further, graphene based nanoadditives at 0.05 wt % in gasoline, diesel and butanol are also investigated.
Technical Paper

Transitioning from IC Engine to Electric Vehicle: An Optimized Wheel End Solution

2020-10-05
2020-01-1632
This paper discusses the change in vehicle parameters when moving from a conventional internal combustion engine to electric motor. It discusses the impact on the wheel end bearings. Typically these include higher GAWRs (Gross Axle Weight Rating) at lower center of gravity heights. These changes require bearings to handle higher loads. Typically, larger loads will increase the bearing size and with it the mounting interface dimensions to auxiliary components. Timken demonstrates an alternative bearing design that can handle higher vehicle GAWRs but would allow for continuity in the surrounding brake corner components – saving OEMs significant design costs and delays.
Technical Paper

Real-World Application of Variable Pedal Feeling Using an Electric Brake Booster with Two Motors

2020-10-05
2020-01-1645
A new type of electric brake booster, which can control brake pedal feeling completely with software, has been developed to explore how a brake system can be used to differentiate and personalize vehicles. In the future, vehicles may share an increasing amount of hardware and rely more heavily on software to differentiate between models. Car sharing, vehicle subscriptions, and other new business models may create a new emphasis on personalization of vehicles that may be achieved most cost effectively using software. This new brake booster controls brake pedal force and brake pressure independently based on the brake pedal stroke so that the pedal feeling is completely defined by software. The booster uses two electric motors and one master cylinder. One electric motor controls pedal force and provides an assist force that amplifies the force that the driver applies to the brake pedal.
Technical Paper

Enclosure-In-Chamber Setup to Achieve Near-Zero Background Concentrations for Brake Emissions Testing

2020-10-05
2020-01-1634
Measuring brake emission is still a challenging non-standardized task. Extensive research is ongoing. Updates of work in progress are presented at SAE Brake Colloquium and PMP meetings. However, open items include how to achieve lower background concentration and how to design the brake enclosure. A low background concentration is essential as brake events are short and some emit in the range of reported background levels. Hence these emissions are difficult to distinguished from the background level. Even more critical, a high background concentration can result in a wrong particle number emissions value, either overestimated, background counted as emissions, or underestimated, background level subtracted, and low emission events no longer detected and counted. However, reducing the background level to less than 100 #/cm³ appeared to be quite challenging.
Technical Paper

Topology Optimization of Brake Caliper

2020-10-05
2020-01-1620
The objective of the research is to develop a lightweight yet stiff, 2 piston fixed brake caliper which can be used in formula student race car. To make a race car, its components need to be lighter. To stop a car with minimum stopping distance, it needs to have a sophisticated braking system with well-designed components. The designing of the caliper is carried out on the Altair Inspire software. The topology optimization algorithm is used to minimize the weight of the caliper without compromising the stiffness. The structural analysis is also carried out on the Altair Inspire. The caliper is also tested for fatigue failure using Ansys.
Technical Paper

Installation Effects on the Flow Generated Noise From Automotive Electrical Cooling Fans

2020-09-30
2020-01-1516
With the electrification of road vehicles comes new demands on the cooling system. Not the least when it comes to noise. Less masking from the driveline and new features, as for example, cooling when charging the batteries drives the need for silent cooling fans. In this work a novel e-fan is studied in different generalized installations and operating conditions. The fans (a cluster configuration) are installed in a test rig where the operation could be controlled varying the speed, flow rate and pressure difference over the fan. On the vehicle side of the fan a generalized packaging space (similar to an engine bay for conventional vehicles) is placed. In this packaging space different obstruction can be placed to simulate the components and radiators used in the vehicle. Here generalized simple blocks in different configuration are used to provide well defined and distinct test cases.
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