scholarly journals Effect of port injection pressure on mixture quality in Homogeneous charges compression ignition (HCCI) engine

The purpose of this study is to investigate the effect of fuelinjection pressure onhomogeneous charge formation and performanceand emission characteristics of Homogeneous charge compression ignition engine. The fuel injection pressure isone of the primary parameter for improvingthe homogeneity of the mixture and governing the power output and emission characteristics of HCCI engine. In this investigation, diesel fuelwasinjected at different injection pressuresas 2bar, 3bar, 4bar and 5bar respectively throughbyport fuel injector. The experimental investigationsshow that increasing the fuel injection pressure will promote the fuel to penetrate with air and creates well pre mixedair/fuel charge.The result shows, the specific fuel consumption (SFC) of HCCI engine isslightlyhigherthan the SFC of conventional diesel engine.The HCCI engine with 3bar injection pressure operated engine has lower SFC values compared to other injection pressure operated HCCI engine.The brake thermal efficiency of HCCI engine, operated with 3barinjection pressure has maximum BTE values over the other injection pressure operated engine.From theresult, it is observed that HCCI engine has lower smoke density values compared to conventional diesel engine andfurther reducedby increasing the fuel injection pressure. The 3bar injection pressure operated HCCI engine has emitted lower smoke densitycompared to other injection pressure operated HCCI engine. The 3bar injection pressureoperated HCCIengine hasemittedmaximum oxides of nitrogen (NOx) emissions than the other injection pressure operated HCCI engine. Other exhaust emissions of carbon monoxide (CO) and hydrocarbon (HC)emissions are increased when compared toconvention diesel engine

2018 ◽  
Vol 7 (4.24) ◽  
pp. 157 ◽  
Author(s):  
P Moulali ◽  
T H Prasad ◽  
B D Prasad

In this paper the emission characteristics and performance of various bio diesel fuels (Tyre pyrolysis oil (TPO), Micro algae oil and Pig animal fat oil) were experimented. A single cylinder, water cooled diesel engine was modified in to homogeneous charge compression ignition engine (HCCI) with adopted port fuel injection (PFI) technique. The effects of air fuel ratio, intake temperature, injection pressure and EGR rate exhaust emissions were explained in a broad manner. The analysis of the exhaust emissions are integrated to oxides of Nitrogen (NOx), Carbon Monoxide (CO), unburned hydro carbons (UHC), smoke and soot. The performance analysis was also included on specific fuel consumption and break thermal efficiency. The basic requirements for HCCI engine is the homogeneous mixture preparation of air and fuel. This mixture formation was done by adopting port fuel injection technique and external devices were also used for bio diesel vaporization and mixture preparation. The combustion processes were measured with different EGR system.  The experimental results of different bio diesel fuels with HCCI engine mode were recorded and evaluated. A small increase in CO and HC emissions were observed with increasing bio diesel content due to slow evaporation rate of bio diesel. A significant reduction in NOx emission was also observed with respect to difference in bio diesel blends. Micro algae oil was found more stable compared with other bio diesel fuels due to the property of fuel vaporization and low heat releasing.


Author(s):  
S. Gowthaman ◽  
G. Balamurugan

Homogeneous Charged Compression Ignition engine (HCCI) is a suitable replacement of conventional diesel engines as it provides higher thermal efficiency and low oxides of emission (NOx) and particulate emissions. In HCCI engine, direct controlling of ignition timing is not possible. But it can be controlled by varying the engine parameters such as fuel injection pressure, inlet air temperature and exhaust gas recirculation. In this study, HCCI engine is controlled with changing the injection pressure of the fuel and analysed for the effect of injection pressure of the fuel for emission and performance of Karanja methyl ester fuel. The experiments were conducted on HCCI engine with fuel injection pressures of 2 bar, 3 bar, 4 bar and 5 bar and the optimum fuel injection pressure is found out. The results show that, the brake thermal efficiency is increased when the injection pressure is increased due to better atomisation and fuel penetration and also resulted in low emissions (NOx, smoke) compared with diesel engine.


Author(s):  
Hoin Kang ◽  
Jerald A. Caton ◽  
Seangwock Lee ◽  
Seokhwan Lee ◽  
Seungmook Oh

LPG (Liquefied Petroleum Gas) has been widely used as an alternative fuel for gasoline and diesel vehicles in light of clean fuel and diversity of energy resources. But conventional LPG vehicles using carburetors or MPI fuel injection systems can’t satisfy the emissions regulations and CO2 targets of the future. Therefore, it is essential to develop LPG engines of spark ignition or compression ignition type such that LPG fuel is directly injected into the combustion chamber under high pressure. A compression ignition engine using LPG is the ideal engine with many advantages of fuel economy, heat efficiency and low CO2, even though it is difficult to develop due to the unique properties of LPG. This paper reports on numerical and experimental studies related to LPG fuel for a compression ignition engine. The numerical analysis is conducted to study the combustion chamber shape with CATIA and to analyze the spray and fluid behaviors with FLUENT for diesel and LPG (n-butane 100%) fuels. In one experimental study, a constant volume chamber is used to observe the spray formation for the chamber pressure 0 to 3MPa and to analyze the flame process, P-V diagram, heat release rate and emissions through the combustion of LPG fuel with the cetane additive DTBP (Di-tert-butyl peroxide) 5 to 15 wt% at 25MPa of fuel injection pressure. In engine bench tests, experiments were performed to find the optimum injection timing, lambda, COV and emissions for the LPG fuel with the cetane additive DTBP 5 to 15 wt% at 25MPa fuel injection pressure and 1500 rpm. The penetration distance of LPG (n-butane 100%) was shorter than that of diesel fuel and LPG was sensitive to the chamber pressure. The ignition delay was in inverse proportion to the ambient pressure linearly. In the engine bench tests, the optimum injection timing of the test engine to the LPG fuel with DTBP 15 wt% was about BTDC 12° CA at all loads and 1500 rpm. An increasing of DTBP blending ratio caused the promotion of flame and fast burn and this lead to reduce HC and CO emissions, on the other hand, to increase NOx and CO2 emissions.


Work has been carried out using four stroke single cylinder diesel engine with retrofit attached with fuel injector and at optimum injection pressure 210 bar and 230 BTDC. The main purpose of using retrofit is to achieve HCCI (Homogeneous charge compression ignition) with which emissions can be reduced. Four Variants of retrofits were used and with V-cut type retrofit it was found that there is reduction in toxic emission like CO and NO but there was slight increase in HC emission when compared with normal fuel injector. Engine performance was compared with normal injector and injector with V-cut and it was found that Break thermal efficiency was increased by 0.25% at full load and 1.53% at 80% load and specific fuel consumption decreased by 0.01%.


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