IndicatedworkandIMEPIndicated work (per cylinder) is defined on the basis oftheIndicatordiagramshownearlierW,= Φ p.dvcycleIndicated Mean Effective Pressure (Mean IndicatedPressure)W,=ppdvWcycleIMEP=Pmi=1VsVs11EffectiveworkandBMEPEffective work is the work delivered at the outputflangeof the engine per cycle and per cylinder2元k1W.:IM-dalangZcBrake Mean Effective Pressure (or just Mean EffectivePressure)W.BMEP=PmeVs126
6 Indicated work and IMEP Indicated work (per cylinder) is defined on the basis of the Indicator diagram shown earlier i cycle W p dV = ⋅ ∫ Indicated Mean Effective Pressure (Mean Indicated Pressure) i cycle i mi S S W p dV W IMEP p V V = ⋅ = = = ∫ 11 Effective work and BMEP Effective work is the work delivered at the output flange of the engine per cycle and per cylinder 2 0 1 k e flange C W M d Z π = ⋅ ⋅ α ∫ Brake Mean Effective Pressure (or just Mean Effective Pressure) e me S W BMEP p V = = 12
EngineefficiencyindicesOcombCombustionefficiencyNcombQfQimHeat input efficiencyng=Qcomb$p.dvW,cycleThermodynamicefficiencyNd =QnT -dscombustionW.BMEPMechanical efficiencynm=W,IMEP13OverallEngineEfficiencyWne2nmt'Icomb0f147
7 Engine efficiency indices Combustion efficiency , comb comb f f L f Q Q m h Q η = = ⋅ Heat input efficiency in q comb Q Q η = Thermodynamic efficiency i cycle td in combustion p dV W Q T dS η ⋅ = = ⋅ ∫ ∫ Mechanical efficiency e m i W BMEP W IMEP η = = 13 Overall Engine Efficiency e e m td q comb f W Q η η η η η = = 14
IndicatedPower&BrakePowerofengineIndicatedPowerpercylinder&overallWN=pav.=P=Pav.NZPiteyl =kkkBrakePowerofengineP=W.NZe= Pav.NZkk15Engine TorqueDefinition of Brake Torque developed by engineZc-V.NZC=MP=M-2元Ng=PmeV,Pm-k2元kRelationshipto instantaneous enginetorque2元k1Zc_.W.MB=IMe'daflan2元k2元k168
8 Indicated Power & Brake Power of engine Indicated Power per cylinder & overall , i E E E C i cyl mi s i mi s W N N N Z P p V P p V k k k ⋅ = = ⋅ ⇒ = ⋅ Brake Power of engine e E C E C B me s W N Z N Z P p V k k ⋅ ⋅ = = ⋅ 15 Engine Torque Definition of Brake Torque developed by engine 2 2 E C C s B B E me s B me N Z Z V P M N p V M p k k π π ⋅ = ⋅ = ⋅ ⇒ = ⋅ Relationship to instantaneous engine torque 2 0 1 2 2 k C B e flange Z M W M d k k π α π π = ⋅ = ⋅ ⋅ ∫ 16