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Journal Article

Using 2d Infrared Imaging for the Analysis of Non-Conventional Fuels Combustion in a Diesel Engine

2015-04-14
2015-01-1646
The common realization of the necessity to reduce the use of mineral sources is promoting the use of alternative fuels. Big efforts are being made to replace petroleum derivatives in the internal combustion engines (ICEs). For this purpose it is mandatory to evaluate the behavior of non-conventional fuels in the ICEs. The optical diagnostics have proven to be a powerful tool to analyze the processes that take place inside the engine. In particular, 2d imaging in the infrared range can reveal new details about the effect of the fuel properties since this technique is still not very common. In this work, a comparison between commercial diesel fuel and two non-conventional fuels has been made in an optically accessible diesel engine. The non-conventional fuels are: the first generation biofuel Rapeseed Methyl Ester (RME) and an experimental blend of diesel and a fuel with high glycerol content (HG).
Technical Paper

UV-Visible Imaging of PCCI Engine Running with Ethanol/Diesel Fuel

2012-04-16
2012-01-1238
Premixed charge compression ignition (PCCI) has been shown to be a promising strategy to simultaneously reduce emissions while realizing improved fuel economy. PCCI combustion uses high levels of pre-combustion mixing to lower both NOx and soot emissions by ensuring low equivalence ratio and low flame temperatures. The high level of pre-combustion mixing results in a primarily kinetics controlled combustion process. In this work, optical diagnostics have been applied in a transparent DI diesel engine equipped with the head of Euro5 commercial engine and the last generation CR injection system. In order to realize the PCCI combustion the injection of neat ethanol has been performed in the intake manifold. The engine run in continuous way at 1500 rpm engine speed and commercial diesel fuel has been injected into the cylinder. The PCCI combustion has been analyzed by means of UV- Visible digital imaging and the mixing process, the autoignition of the charge have been investigated.
Technical Paper

Temperature Measurements of the Piston Optical Window in a Research Compression Ignition Engine via Thermography and Templugs

2018-04-03
2018-01-0083
Internal combustion engines are characterized by high pressure and thermal loads on pistons and in cylinders. The heat generated by the combustion process is dissipated by means of water and oil cooling systems. For the best design and optimization of the engine components it is necessary to know the components temperature in order to estimate the thermal flows. The purpose of this work is to measure the piston sapphire window temperature in a research optically accessible engine by combining two different techniques: measurements with templugs and with thermography. The method is very simple and can provide a reliable value of temperature within a small interval. It fits well for applications inside the engine because of its low technical level requirements. It consists of application of temperature sensitive stickers on the target component that makes it a very robust method, not affected by piston movement.
Technical Paper

Optical Investigation of Injection and Combustion Phases of a Fouled Piezoelectric Injector in a Transparent CR Diesel Engine

2013-04-08
2013-01-1591
This study was conducted to determine the effects of the fouling process on the piezoelectric injectors in a transparent common-rail diesel engine. Piezoelectric injectors are characterized by a ceramic actuator that can dilate or retract when it receives a pulse of current. The piezo element controls a valve, which creates an imbalance in the pressure that is exerted at each end of the needle, causing the needle rising or closing. Two same model injectors were tested; one was new and the other one was fouled on a vehicle. The aim of the experimental investigation was to evaluate the performance of a new and a fouled piezoelectric injector in terms of injection and flame evolution. It was evaluated how the nozzle carbon deposits affect the injection quantity and combustion. The experimental apparatus was a single-cylinder research engine equipped with a Euro 5 multi-cylinder head. A second-generation common rail injection system and 6-hole piezoelectric injectors were used too.
Technical Paper

Investigation of the Injection Process in a Research CR Diesel Engine using Different Blends of Propane-Diesel Fuel

2015-09-06
2015-24-2477
Blends of propane-diesel fuel can be used in direct injection diesel engines to improve the air-fuel mixing and the premixed combustion phase, and to reduce pollutant emissions. The potential benefits of usinf propane in diesel engines are both environmental and economic; furthermore, its use does not require changes to the compression ratio of conventional diesel engines. The present paper describes an experimental investigation of the injection process for different liquid preformed blends of propane-diesel fuel in an optically accessible Common Rail diesel engine. Slight modifications of the injection system were required in order to operate with a blend of propane-diesel fuel. Pure diesel fuel and two propane-diesel mixtures at different mass ratios were tested (20% and 40% in mass of propane named P20 and P40). First, injection in air at ambient temperature and atmospheric pressure were performed to verify the functionality of the modified Common Rail injection system.
Technical Paper

IR Imaging of Premixed Combustion in a Transparent Euro5 Diesel Engine

2011-09-11
2011-24-0043
In the present paper, infrared (IR) measurements were performed in order to study the development of injection and combustion in a transparent Euro 5 diesel engine operating in premixed mode. An elongated single-cylinder engine equipped with the multi-cylinder head of commercial passenger car and with common rail (CR) injection system, respectively, was used. A sapphire window was set in the bottom of the combustion chamber, and a sapphire ring was placed between the head and the top of the cylinder line. Measurements were carried out through both accesses by a new high-speed infrared (IR) digital imaging system obtaining information that was difficult to achieve by the conventional UV-visible camera. IR camera was able to detect the emitted light in the wavelength range 1.5-5 μm that is relevant for the emission bands of CO₂ and H₂O. The evaporation phase of pre and main injection, and subsequent combustion evolution were analyzed.
Technical Paper

Experimental and Numerical Characterization of Diesel Injection in Single-Cylinder Research Engine with Rate Shaping Strategy

2017-09-04
2017-24-0113
The management of multiple injections in compression ignition (CI) engines is one of the most common ways to increase engine performance by avoiding hardware modifications and after-treatment systems. Great attention is given to the profile of the injection rate since it controls the fuel delivery in the cylinder. The Injection Rate Shaping (IRS) is a technique that aims to manage the quantity of injected fuel during the injection process via a proper definition of the injection timing (injection duration and dwell time). In particular, it consists in closer and centered injection events and in a split main injection with a very small dwell time. From the experimental point of view, the performance of an IRS strategy has been studied in an optical CI engine. In particular, liquid and vapor phases of the injected fuel have been acquired via visible and infrared imaging, respectively. Injection parameters, like penetration and cone angle have been determined and analyzed.
Technical Paper

Characterization of Combustion and Emissions of a Propane-Diesel Blend in a Research Diesel Engine

2016-04-05
2016-01-0810
The interest of the vehicle producers in fulfillment emission legislations without adopting after treatment systems is driving to the use of non-conventional energy sources for modern engines. A previous test campaign dealing with the use of blends of diesel and propane in a CI engine has pointed out the potential of this non-conventional fuel for diesel engines. The soft adaptation of the common rail injection system and the potential benefits, in terms of engine performances and pollutant emissions, encourage the use of propane-diesel blends if an optimization of the injection strategies is performed. In this work, the performances of a propane-diesel mixture in a research diesel engine have been investigated. The injection strategies of Euro 5 calibration have been used as reference for the development of optimized strategies. The aim of the optimization process was to ensure the same engine power output and reduce the pollutant emissions.
Technical Paper

Assessment of the New Features of a Prototype High-Pressure “Hollow Cone Spray” Diesel Injector by Means of Engine Performance Characterization and Spray Visualization

2018-09-10
2018-01-1697
The application of more efficient compression ignition combustion concepts requires advancement in terms of fuel injection technologies. The injector nozzle is the most critical component of the whole injection system for its impact on the combustion process. It is characterized by the number of holes, diameter, internal shape, and opening angle. The reduction of the nozzle hole diameter seems the simplest way to promote the atomization process but the number of holes must be increased to keep constant the injected fuel mass. This logic has been applied to the development of a new generation of injectors. First, the tendency to increase the nozzle number and to reduce the diameter has led to the replacement of the nozzle with a circular plate. The vertical movement of the needle generates an annulus area for the fuel delivery on 360 degrees, so controlling the atomization as a function of the vertical plate position.
Journal Article

Alternative Diesel Fuels Effects on Combustion and Emissions of an Euro4 Automotive Diesel Engine

2009-09-13
2009-24-0088
The present paper describes the first results of a cooperative research project between GM Powertrain Europe and Istituto Motori of CNR aimed at studying the impact of Fatty-Acid Methyl Esters (FAME) and gas-to-liquid (GTL) fuel blends on the performance, emissions and fuel consumption of modern automotive diesel engines. The tests were performed on the architecture of GM 1.9L Euro4 diesel engine for passenger car application, both on optical single-cylinder and on production four-cylinder engines, sharing the same combustion system configuration. Various blends of biodiesels as well as reference diesel fuel were tested. The experimental activity on the single-cylinder engine was devoted to an in-depth investigation of the combustion process and pollutant formation, by means of different optical diagnostics techniques, based on imaging multiwavelength spectroscopy.
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