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Power unit – engine
Published in Andrew Livesey, Motorcycle Engineering, 2021
Volumetric efficiency – In other words, the efficiency of the engine in getting fuel and air to fill the cylinder. The fact that an engine has cylinders of 1 liter (61 cu in) does not mean that you are getting that amount of air and fuel into the cylinders. The flow of gas is affected by a number of points, mainly: Size, shape, and number of valvesValve timingSize and shape of the inlet and exhaust portsShape and location of the combustion chamberBore-to-stroke ratioEngine speedType of induction tract – air filter, carburetor or throttle body, inlet manifoldType of exhaust system – manifold, silencers, cat, and pipe layout
Internal Combustion Engines
Published in D. Yogi Goswami, Frank Kreith, Energy Conversion, 2017
David E. Klett, Elsayed M. Afify, Kalyan K. Srinivasan, Timothy J. Jacobs
Because a certain minimum amount of air is required for complete combustion of a given amount of fuel, it follows that the maximum power output of an engine is directly proportional to its air-flow capacity. Therefore, although not affecting the fuel conversion efficiency of the engine in any way, the volumetric efficiency directly affects the maximum power output for a given displacement and thus can affect the efficiency of the overall system in which the engine is installed because of the effect on system size and weight. Volumetric efficiency is affected primarily by intake and exhaust valve geometry; valve lift and timing; intake port and manifold design; mixing of intake charge with residual exhaust gases; engine speed; ratio of inlet pressure to exhaust back pressure; and heat transfer to the intake mixture from warmer flow passages and combustion chamber surfaces. For further information on the fundamentals of IC engine design and operation, see Taylor (1985), Heywood (1988), Stone (1993), and Ferguson and Kirkpatrick (2001).
Liquefied Petroleum Gas
Published in Arumugam S. Ramadhas, Alternative Fuels for Transportation, 2016
Mohamed Younes El-Saghir Selim
It has been found that in the case of using LPG in SI engines, the burning rate of fuel is increased, and thus, the combustion duration is decreased. As a consequence of this, the cylinder pressures and temperatures predicted for LPG are higher than those obtained for gasoline. The maximum cylinder pressures and temperatures predicted for LPG are higher. This may cause some damages on engine structural elements. LPG reduces the engine volumetric efficiency and, thus, engine effective power. Furthermore, the decrease in volumetric efficiency also reduces the engine effective efficiency and consequently increases specific fuel consumption. It has been also found that LPG decreases the mole fractions of CO and NO included in the exhaust gases. Furthermore, LPG has negative effects on engine performance, fuel economy, and engine structural elements when it is used at the same fuel–air equivalence ratios as gasoline, however, it has positive effects on obnoxious exhaust emissions such as CO and NO.
Experimental evaluation of cottonseed oil-camphor binary blends on diesel engine performance, combustion, exhaust and cyclic variance parameters
Published in Biofuels, 2023
Manikandaraja Gurusamy, Chandrasekaran Ponnusamy
Volumetric efficiency is the parameter defining the breathing level of the engine and effective utilization of the in-cylinder volume [55]. Therefore, higher volumetric efficiency is needed for the good performance of the engine. As seen in the Figure 2, the C70CSO30 blend has the highest volumetric efficiency of 82.50% and is followed by C50CSO50, diesel and C30CSO70. The lower cetane number of C70CSO30 increases the rate of pressure rise and is followed by a high rate of expansion process, which leads to reduction in temperature in the exhaust process. So, the expansion rate of the residual gases is found to be reduced allowing the engine to take more volume of air for the cycle. But, in the case of C30CSO70 blend, high cylinder temperature during the exhaust stroke leads to more expansion of residual gases present in the clearance volume and reduces the amount of air taken by the cylinder for the next cycle [56]. Increasing the proportions of the camphor oil in the blended fuel increases the volumetric efficiency whereas volumetric efficiency decreases with increase in the proportions of cottonseed oil in the blended fuel.
Modelling of an electro-hydraulic variable valve actuator for camless engines aimed at controlling valve lift parameters
Published in International Journal of Control, 2021
Alessandro di Gaeta, Carlos Ildefonso Hoyos Velasco, Veniero Giglio
To meet increasingly severe exhaust gas emission standards and customer expectations in terms of fuel reduction and performance, improvement of internal combustion engine technology is required. In this regard, the filling and emptying of engine cylinders, regulated by opening and closing of inlet and exhaust valves, play a key role. Volumetric efficiency, as well as in-cylinder fluid dynamics, energy losses and exhaust gas residuals, which significantly influence fuel economy and pollutant formation, depend on operating parameters such as valve timing (or anchoring), lift trajectory, lift maximum and opening duration (Heywood, 1988). These parameters, in turn, depend on the systems used for valve actuation. The simplest is the camshaft solution, a purely mechanical device in which cam profiles impose the same valve lift timings and trajectories over the whole operating range of the engine. Despite its simplicity, this solution is too constrained and precludes applications requiring higher valve actuation flexibility. For example, implementation of the Miller cycle, which achieves better thermodynamic efficiency by an effective expansion ratio higher than the effective compression ratio, made possible by delayed closing of the inlet valve during the compression stroke. Hence the camshaft solution has the disadvantage of lower power density.
Investigations on Biogas Fueled Dual Fuel DIesel Engine Employing Dimethyl Carbonate as a Fuel Blend
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Nihal Mishra, Abhishek Thapliyal, Shubham Mitra, Feroskhan M, Shyam Kumar M B
Biogas is usually produced by a method that uses anaerobic digestion with methogen organisms or by fermenting biodegradable materials (Khoiyangbam, Gupta, and Kumar 2011). Many researchers use biogas like alternative fuel in the present diesel engines in the absence of any major changes. This is because of its ignition by self-temperature is more, the burning capacities are less and the velocity of flame is also less (Swami Nathan, Mallikrajuna, and Ramesh 2009). The effects brought about by numerous operating conditions on performance of the engine and releases when compared to the usual diesel-fueled CI engines are observed and recorded. Since the self-ignition temperature is on the higher side, biogas is used alongside diesel in dual fuel operation. In the working of a dual fuel engine, when the charge consisting of a mixture of biogas and air is compressed, slight proportion of diesel is injected into the mixture, which is identified as the pilot fuel. This fuel introduced undergoes a self-ignition and then ignites the biogas which is inducted. The primary benefit of dual fuel engines is their ability to run using an extensive combination of gaseous fuels without the headache of modifying the engine repeatedly. In the conventional naturally aspirated engines, air is inducted into the combustion chamber at environmental pressure due to the downward motion of the piston. A method called supercharging is employed that increases the volumetric efficiency of the engine. This happens due to the rise in the density of intake air. It was also observed that the HC emissions underwent a significant decline (Patel, Dubey, and Feroskhan 2020).