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 12:02 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
2. Find the vessel displacement when running on MDO. Then , find
the overall engine efficiency and plot a P-V chart the
air-standard diesel cycle the engine is following assuming perfect
combustion and total air excess ratio of 2.5; show pressure,
temperature and specific volume values for all corner points of the
cycle.
3. For the NG fuel mode, plot on a p-v chart the air-standard
Otto Cycle the engine is following assuming perfect combustion and
total air excess ratio of 2.5; show pressure, temperature and
specific volume values for all corner points of the cycle. Finally,
find the Fuel Coefficient of the vessel when running on NG.
4. For both fuel modes, find temperature downstream the
turbocharger compressor and the turbocharger turbine as well
as exhaust pressure and temperature. If coolant water enters the
intercooler at 25 centrigrade and exits at 30 centrigrade, what
should be the coolant water mass flow rate to ensure that
scavenging air temperature is 35 centrigrade? For fresh water,
assume specific heat of 4182 J/kg/K.
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
2. Find the vessel displacement when running on MDO. Then , find
the overall engine efficiency and plot a P-V chart the
air-standard diesel cycle the engine is following assuming perfect
combustion and total air excess ratio of 2.5; show pressure,
temperature and specific volume values for all corner points of the
cycle.
3. For the NG fuel mode, plot on a p-v chart the air-standard
Otto Cycle the engine is following assuming perfect combustion and
total air excess ratio of 2.5; show pressure, temperature and
specific volume values for all corner points of the cycle. Finally,
find the Fuel Coefficient of the vessel when running on NG.
4. For both fuel modes, find temperature downstream the
turbocharger compressor and the turbocharger turbine as well
as exhaust pressure and temperature. If coolant water enters the
intercooler at 25 centrigrade and exits at 30 centrigrade, what
should be the coolant water mass flow rate to ensure that
scavenging air temperature is 35 centrigrade? For fresh water,
assume specific heat of 4182 J/kg/K.