A cargo vessel has admirably coefficient of 500, fuel coefficient of 120,000 and service speed of 19.9 knots. Her propul
Posted: Sat May 21, 2022 12:00 pm
A cargo vessel has admirably coefficient of 500, fuel
coefficient of 120,000 and service speed of 19.9 knots. Her
propulsion is powered by a single 2-S, 9-cyl. marine engine with
compression ratio 22. Cylinder bore 1m and piston stroke 2.5m
directly driving a single fixed-pitch screw propeller , at C-MCR
the engine delivers 40MW of brake power at 100rpm. The engine
can run on diesel fuel (MDO) with formular
C12.3H22.2, lower heating value of 42500
kJ/kg and stoichiometric A/F 14.5 employing a diesel cycle or
natural gas (NG) mainly consisting of methane with formula
CH4, lower heating value of 49770 kJ/kg and
stoichiometric A/F 17.2 employing an Otto Cycle. The mechanical
efficiency of the engine is 0.95 and all partial engine
efficiencies are the same regardless of the fuel employed. Finally,
the Fuel Coefficient of the vessel when running on MDO is
120,000.
1. Find SFOC of the engine when running on either fuel mode (MDO
or NG). Assuming that both ambient and scavenging air receiver
temperature is 35 centrigrade, entrapped air efficiency is 1.0 and
total air excess ratio is 2.5. Find the scavenging receiver air
pressure required for both fuel modes of the engine (MDO and NG).
Then, calculate the turbocharger compressor power requirement and
turbocharger turbine power production assuming that isentropic
efficiency is 0.85 and 0.80 respectively and the mechanical
turbocharger efficiency is 0.98. Finally, write the perfect
combustion reaction for each fuel mode showing the mass amounts of
fuel, air and combustion product components per cylinder and per
cycle. Ambient pressure is 1bar.
For air R = 287 J/kg/K, Y = 1.4; for exhaust /combustion gas R =
277 J/kg/K, Y = 1.3
coefficient of 120,000 and service speed of 19.9 knots. Her
propulsion is powered by a single 2-S, 9-cyl. marine engine with
compression ratio 22. Cylinder bore 1m and piston stroke 2.5m
directly driving a single fixed-pitch screw propeller , at C-MCR
the engine delivers 40MW of brake power at 100rpm. The engine
can run on diesel fuel (MDO) with formular
C12.3H22.2, lower heating value of 42500
kJ/kg and stoichiometric A/F 14.5 employing a diesel cycle or
natural gas (NG) mainly consisting of methane with formula
CH4, lower heating value of 49770 kJ/kg and
stoichiometric A/F 17.2 employing an Otto Cycle. The mechanical
efficiency of the engine is 0.95 and all partial engine
efficiencies are the same regardless of the fuel employed. Finally,
the Fuel Coefficient of the vessel when running on MDO is
120,000.
1. Find SFOC of the engine when running on either fuel mode (MDO
or NG). Assuming that both ambient and scavenging air receiver
temperature is 35 centrigrade, entrapped air efficiency is 1.0 and
total air excess ratio is 2.5. Find the scavenging receiver air
pressure required for both fuel modes of the engine (MDO and NG).
Then, calculate the turbocharger compressor power requirement and
turbocharger turbine power production assuming that isentropic
efficiency is 0.85 and 0.80 respectively and the mechanical
turbocharger efficiency is 0.98. Finally, write the perfect
combustion reaction for each fuel mode showing the mass amounts of
fuel, air and combustion product components per cylinder and per
cycle. Ambient pressure is 1bar.
For air R = 287 J/kg/K, Y = 1.4; for exhaust /combustion gas R =
277 J/kg/K, Y = 1.3