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Utilization of Biofuels in Compression-Ignition Engines
Published in K.A. Subramanian, Biofueled Reciprocating Internal Combustion Engines, 2017
The inducted air is compressed by moving a piston toward TDC. The in-cylinder pressure and temperature of air increase during a compression stroke. The crank angle can be from 10° to 20° before TDC, and a high cetane number fuel is injected into the engine’s cylinder using an injection system. The pump in the fuel tank supplies fuel to the injection pump, and the injection pump supplies the appropriate quantity of fuel at the desired injection pressure. Fuel with high injection pressure is directly injected into the cylinder by the injectors at the end of a compression stroke.
Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
C.i. engines are not throttled, but are controlled by regulating the amount of fuel injected and the injection timing. Because of the required high injection pressures, large diesel engine fuel injectors are mechanically rather than electrically driven; systems for small engines may use electric pumps. Three types of systems are used: injection pump, unit injector, and common-rail (Figure 68.10). In an injection pump system, a central pump timed to the camshaft delivers fuel to nozzles located at each cylinder. The pump typically has individual barrels for each cylinder, but a single barrel with a fuel distributor is also used. In a unit injector system, there are a pump and nozzle on each cylinder, driven by a shaft running over all the cylinder heads. In a common rail system, a central pump supplies high-pressure fuel to a common header, and each cylinder has a solenoid-operated valve and nozzle. Common rail systems are suitable only for low injection pressures (small engines); injection pump systems are suitable for medium injection pressure (medium engines); unit injector systems are suitable for high injection pressures (large engines) The injection start and duration are varied according to engine load and operating conditions. In the past, the control was generally accomplished through purely mechanical means and consisted mainly of increasing the injection duration in response to increased torque demand and advancing injection timing at higher speeds. In recent years, however, electronically controlled common rail systems, injector pumps, and unit injectors have become common. In the injector pump and unit-injector systems, the power is supplied mechanically, but fuel delivery is controlled by unloading solenoids. Electronic control allows fuel delivery to be carefully adjusted in response to engine operating conditions and is useful in achieving low emissions.
The diesel engine
Published in M.J. Nunney, Light and Heavy Vehicle Technology, 2007
A once typical front mounted timing drive for a diesel engine comprises four gears: one each for the camshaft and fuel injection pump drive, a crankshaft pinion, and an idler gear that engages the other three (Figure 5.3). All four gears have teeth of helical form and are produced from steel for this type of heavy-duty application. Alternatively, a triangulated layout of double-row or triple-row roller chain has been used for the timing drive, the length of the chain being kept to a minimum so that the effects of wear have the least disturbance on the timing of the fuel injection pump. In more recent practice, there has been a need to ensure greater precision of operation for the valve train and unit injectors, which has resulted in the camshaft for in-line cylinder engines being mounted either high in the cylinder block, or on the cylinder head itself, and in both cases this inevitably entails using an extended (Figure 2.5) and sometimes a compound (Figure 2.20) train of gears. Furthermore, the gear train may be mounted at the rear of the engine with the input gear being sandwiched between the crankshaft flange and the flywheel (Figure 2.20). The purpose of this reversal in arrangement of the timing drive will be understood by recalling that when a crankshaft suffers a period of torsional vibration, its maximum amplitude will be greatest at the front end (Section 1.9). Therefore to reduce vibration, wear and now importantly noise in the timing drive, it is clearly advantageous to mount the gear train at the opposite end of the crankshaft where the torsional vibration is much less. An ideal but hardly practicable course of action would be to site the timing gear train at the nodal point (position of no vibration) of the crankshaft, but this unhelpfully lies somewhere between the rear crankthrows. Another advantage of a rear mounted timing drive is that it can provide a suitably geared power take-off facility (Section 14.5).
Comparative investigation of the effects of lower and higher alcohols/bio-diesel blends on engine performance and emissions characteristics of a diesel engine
Published in International Journal of Ambient Energy, 2020
Jeya Jeevahan, S. Lakshmi Sankar, P. Karthikeyan, V. Sriram, G. Britto Joseph
The experimental setup is shown in the Figure 1. Fuel A and Fuel B are kept inside the fuel tank (1) and (2) before the experiment is started. The measured quantity of fuel is shifted to fuel blender (3) using the respective valves. Fuel blender is graduated with the measurements and the required blend is mixed in the fuel blender. A four stroke compression ignition single cylinder IC engine (7) is used in the experiment. The engine has a power output of 5.2 kW with a maximum attainable speed of 2000 rpm. The cylinder bore diameter, stoke length and the length of connecting rod are 87.5 mm, 110 mm and 234 mm respectively. The compressed air is supplied through an air filter (8) from the intake manifold (6) and it enters into the cylinder during the suction stroke. The air is further compressed during the compression stroke. Fuel injection pump (4) sends a required amount of fuel blend to the fuel injector (5) that sprays the atomised fuel particles at a particular timing so that the combustion takes place inside the IC engine during working stroke. The energy is released and the mechanical output is obtained. The exhaust gases escape through the exhaust manifold (11). A silencer is used to reduce the velocity of exhaust gases thus reducing the noise level. The IC engine is connected to an eddy current dynamometer (13) for applying load conditions. The dynamometer parameters and speed measurement and settings can be adjusted with the help of a control panel (14) which is finally connected to a computer or processing unit. The parameters can also be adjusted on the display unit attached to the control panel. A secondary pipeline is taken out of the exhaust pipe and is connected to an AVL Digas 444 gas analyzer that can be used for measuring the emissions levels.