The Internal-Combustion Engine in Theory and Practice - PDF
Added on 2021-04-19
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Running head: IC ENGINE 1IC ENGINEName of StudentInstitution Affiliation
IC ENGINE 2Question 1.Brake specific fuel consumption is the ratio of the amount of fuel consumed to break power developed in a unit time.In other words, it is a measure of the fuel efficiency or how efficiency a given amount of fuel is being converted into a specific amount of horsepower[ CITATION Cha16 \l 2057 ].Units of BSFC in SI units are,BSCF = ¿finf(Kghour)B.P(KW) = ¿fB.P{ KgKW.hr}Units of BSFC in English units are,BSCF = inf(1bhour)B.P(hp) = infB.P{1bhp.hr}Break power is the power available at the crank to supply to the gearbox. The magnitude of the brake power depends on how efficient the engine cylinder converts fuel in the indicated power and how efficient the engine parts in transferring that indicated power to the shaft power. The lesser the frictional losses, the greater is the brake power[ CITATION Cha16 \l 2057 ].In the automotive applications, the Break specific fuel consumption is applied in the evaluation of the efficiency of the internal combustion engines (ICE).Let’s say we have two engines of approximately equal power. That is their respective torque and horsepower curves are quite similar. One exhibits a BSFC curve lower than the other engine. It means that the one with the lower BSFC curve will accelerate more quickly than
IC ENGINE 3the other. It will also be more responsive to the changes affecting combustion efficiency and require less total spark timing to perform at its best[ CITATION Joh154 \l 2057 ]. The best and worst BSFC values an engine is likely to operate are as shown in the table below:Power(KW)YearEngine typeapplicationBSFC(1b/hp.h)BSFC(kW.h)Energyefficiency572003Toyota 1nz.FXEgasolineToyotaPrius car0.370225(5)36.4%631991GM Saturn 14engine. GasolineSaturn S-Series cars0.411250(1)32.5%881990Audi 2.5 L TDIAudi 100car0.326198(13)42.6%951970Lycoming O-320piston gasolineGeneralaviation0.460280(1)29.3%1302007BMW N47 2LturbodieselBMW cars0.326198(12)42.6%Question 2.Brake mean effective pressure refers to the average pressure which, when imposed uniformly on the piston from top to bottom of each of the power stroke, would yield the brake (measured) power output. The brake mean effective pressure is theoretical and has no relationship with the actual cylinder pressures[ CITATION Joh154 \l 2057 ].The term brake mean effective pressure Even if it contains the word “pressure”is not a pressure term but a work term. Brake Mean Effective Pressure = (n × t × 2 × 3.14) / d
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