Latvian Maritime academy

Table 1. Engine specificationRated powerEngine speed at rated powerNumber of cylindersBoreStrokeBoost systemFuel deliveryDisplacementSpecific fuel consumption (rated power mode)LengthWidthHeight125 kW2000 rpm4 in line120 mm140 mmTurbocharger with intercoolerDirect injection system with the BOSCH typehigh-pressure fuel delivery pump6.3 liters224 g/kWh1769 mm826 mm1167 mmThe engine was tested on an engine dynamometer. The specified speed was held to within ±50 rpm,and the specified torque was held to within ±2% of the maximum torque at the test speed. On the highload mode and low engine speed with P e = 67.8 kW and n = 1250 rpm and on the torque and powercurves modes, indexing of the 4th cylinder was performed as well as measurements of all main indices forthe different values of the effective cross-section area of the end of turbine volute acceleration section A.An exception was made for the modes with n = 1800 and 2000 rpm. For this mode, the value of Aremained intact. The reason is sufficient air supply to the cylinder delivered by the compressor ofcommercial turbocharger and thus no need to reduce A value (for increasing Lambda) to have animprovement in combustion efficiency.Turbine, compressor, and turbocharger characteristics were calculated according to equations 1 to 5.All equations were taken from [8].The initial data for defining the characteristics were obtained during tests of the diesel engine with acommercial and an adjusted turbocharger.Turbocharger efficiency is calculated by an empirical expression as0,2857 ê 1 1 turbo 1,045(t01 273) 1 , (1)0,25931,119(tt 273) Ò where t 01is the ambient temperature in degree Celsius, t tis the exhaust gas temperature in degreeCelsius, кis the compressor pressure ratio, and Tis the turbine pressure ratio.The compressor pressure ratio can be calculated as ð / pa ,(2)êêwhere p k is the boost pressure after the compressor, andThe turbine pressure ratio is calculated asÒ pT/ p ex,p a is exhaustion before the compressor wheel.where p T is the exhaust gas pressure before the turbine, and p ex is the exhaust gas pressure afterturbine.Compressor efficiency can be calculated as the isentropic compression enthalpy gauge divided bythe isentropic expansion enthalpy drop:(3) 6.20211.86Ê 0.76553Ê 0.07534 0.003001 3.903 0.0007262where is the rotor speed of turbocharger.Turbine efficiency is calculated as / ÒturbokÊ2ÊÊ2Ê 0.095912 0.0000005358 ,Ê 0.000822432(4)(5)54