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Combustion Aspects of Non-Conventional Reciprocating Internal Combustion Engines
Published in Debi Prasad Mishra, Advances in Combustion Technology, 2023
The major advantage with GDI technology is better fuel economy and improved power output and lesser emissions. These could be achieved because of metering of exact fuel quantity and precise injection timing for various load and speed conditions by ECU. Losses due to throttling and pumping could be very well minimized, thereby, improved efficiency is achieved. Regulated and accurate injection timing enables speed control through the Engine Management System (EMS). However, achieving this control through EMS requires a large memory in ECU. To achieve better performance, control and driveability this is a must. The Engine Management System continually chooses among three combustion modes—viz., ultra-lean, stoichiometric and full power output—based on the air-fuel ratio. For most of the hydro-carbon fuels stoichiometric air-fuel ratio is close to 15:1. But, ultra-lean mode can be 400% leaner (60:1) or even higher in some engines, for a very limited period. These mixtures are very much leaner than in a conventional carburetted engine and reduce fuel consumption quite considerably. Let us look into the details in the following paragraphs.
Gas Power Cycles
Published in Kavati Venkateswarlu, Engineering Thermodynamics, 2020
The evolutionary changes that occurred in case of SI engines from the last two to three decades will be from the carburettor engines to gasoline direct injection (GDI) through multipoint fuel injection (MPFI) engines. Carburettor of conventional SI engines is being replaced by multipoint fuel injection (MPFI) system in which fuel is injected into the intake manifold (called port injection), instead of being injected into the combustion chamber as in CI engines. GDI, also known as petrol direct injection, is a mixture formation system for SI engines that run on gasoline, in which fuel is directly injected into the combustion chamber, in contrast to the older port fuel injection systems or MPFI system. The GDI is proving to be a promising technology to simultaneously increase engine efficiency and specific power output and to potentially reduce exhaust emissions.
Engine systems
Published in Tom Denton, Advanced Automotive Fault Diagnosis, 2020
The engine operates with an almost completely opened throttle valve, which avoids additional alternating charge losses. With stratified charge operation, the lambda value in the combustion chamber is between approximately 1.5 and 3. In the part-load range, GDI achieves the greatest fuel savings with up to 40% at idle compared to conventional petrol injection processes. With increasing engine load, and therefore increasing injection quantities, the stratified charge cloud becomes even richer and emission characteristics become worse.
IMPACT OF OPERATING PARAMETERS ON ENERGY EFFICIENCY AND REGULATED EMISSIONS OF DUAL FUEL DIRECT INJECTED REACTIVITY-CONTROLLED COMPRESSION-IGNITION COMBUSTION
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2021
Murugan Rangasamy, Parthasarthi Kesavan, Yogesh Vaidhiyanathan, Ganesh Duraisamy, Charles Augustin V
In the present investigation, tests have been conducted on a Kirloskar make, Genset diesel engine with required modifications. The test engine has a displacement volume of 661 cc and it can produce a maximum power of 4.4 kW at a rated speed of 1500 rpm. The test engine is attached to the eddy current dynamometer to absorb actual power produced by the test engine. The modification was done on the cylinder head to accommodate both the common rail direct injector (CRDI) and gasoline direct injector (GDI). Figure 1 shows a modified cylinder head-mounted with GDI and CRDI injectors. The position of the injectors is selected carefully to avoid wall impingement and achieve the maximum possible homogeneous air-fuel mixture. CRDI injector is mounted vertically to avoid fuel impingement and offset from the piston bowl center. Similarly, the GDI injector is mounted at 75° inclinations from the base of the cylinder head. GDI fuel supply system comprises of a fuel pump, fuel filter, pressure regulator, and Bosch make GDI injector.
Trends in onroad transportation energy and emissions
Published in Journal of the Air & Waste Management Association, 2018
The mix of fuel delivery systems for new U.S. LDVs is undergoing dramatic changes with the rapid emergence of GDI. In the last 10 years, GDI has gained a growing share of the U.S. market, now exceeding 50% of new LDV sales (EPA 2016e). GDI delivers fuel directly into the cylinder, thereby eliminating fuel transport delay and enabling very precise control of timing and air/fuel ratio. Fuel can be delivered to better match engine load and with more than one injection pulse to achieve staged combustion (Zhao, Lai, and Harrington 1999). Staged combustion helps prevent knock, which enables an increase in compression ratio for improved engine efficiency. Estimates of the fuel economy advantage of GDI engine LDVs versus those with port fuel injection (PFI) range from 1.5% to 30% (NRC 2015). Spray-guided systems, which are referred to as second-generation GDI, produce fewer particles than the first-generation wall-guided systems (Short et al. 2017). This is largely because fuel spray in wall-guided systems impinges on piston and cylinder surfaces more so than for spray-guided systems, which leads to cooling of the fuel spray and more particle formation (Seo et al. 2016).
The gasoline fuel quality impact on fuel consumption, air-fuel ratio (AFR), lambda (λ) and exhaust emissions of gasoline-fueled vehicles
Published in Cogent Engineering, 2019
Shamil Ahmed Flamarz Al-Arkawazi
Gasoline Direct Injection (GDI) has become the preferred technology for spark-ignition engines resulting in greater specific power output and lower fuel consumption, and consequently reduction in CO2 emission. However, GDI engines face a substantial challenge in meeting new and future emission limits, especially the stringent particle number (PN) emissions recently introduced in Europe and China. Studies have shown that the fuel used by a vehicle has a significant impact on engine-out emissions. For study purposes, nine fuels with varying chemical composition and physical properties were tested on a modern turbocharged side-mounted GDI engine with design changes to reduce particulate emissions. The fuels tested included four fuels meeting US certification requirements; two fuels meeting European certification requirements; and one fuel meeting China 6 certification requirements. Two risk safeguard fuels (RSG), representing the properties of worst-case market fuels in Europe and China, were also included. The particle number concentration of the solid particulates was measured in the engine-out exhaust flow at steady state engine operations with load and speed sweeps, and semi-transient load steps. The test results showed a factor of 6 PN emission difference among all certification fuels tested. Combined with detailed fuel analyses, the study evaluated important factors (such as oxygenates, carbon chain length and thermo-physical properties) that cause PN emissions which were not included in the PMI index. Linear regression was performed to develop a PN predictive model which showed improved fitting quality than using PMI (Fatouraie et al., 2018).