Internal Combustion Engine and Specific Fuel Consumption
SOLVED PROBLEMS OF CHAPTER # 13
TITLE: RECPROCTING INTERNAL COMBUSTION ENGINES
PROBLEM # 13.1:
A quantity governed four-stroke, single-cylinder gas engine has a bore of 146mm and a stroke of 280mm.At 475 rev/min and full load the net load on the friction brake is 433 N, and the torque arm is 0.45 m. The indicator diagram gives a net area of 578 mm² and a length of 70 mm with a spring rating of 0.815 bar per mm. calculate the ip,bp, and mechanical efficiency.
GIVEN DATA:
Four stroke single cylinder gas engine n = no. of cylinders = 1
Dia. of cylinder bore = 146 mm = 0.146 m
Length of stroke = L = 280 mm = 0.28 m
N = 475 revolution/min = 475/ 60 rev/sec. = 7.5416 rev/sec.
Full load, break load = W = B = 433 N
Torque arm = R = 0.45 m
Net area of indicator diagram = 578 mm2 = 578 * 10-6 m2
Length of indicating diagram = 70 mm = 70 * 10 -3 m
Spring rating constt. = 0.815 bar/mm
= 0.815 / 10-3 bar /m = 815 bar/m
REQUIRED:
Indicated power = ip =? Brake power = bp =? ηmech = ?
DIAGRAM:
SOLUTION:
Indicated power is given by ip = (Pi * ALnN)/2 _________________ (1)
This formulae is for 4 stroke engine, But
Pi = indicated pressure =? Pi = (net area of diagram)* constt. / Length of the diagram = 578 * 10-6 * 815/ (70 * 10-3) = 6.73 bar A = Area of the bore = (π/4)* d2 = 0.01674 m2 Now equation (1) becomes ip = 6.73 * 105 * 0.01674 * 0.28 * 7.916 * 1/ 2 = 12485.4 watts = 12.4854 Kwatts
Now T = W * R = 194.85 Nm
bp = 2 π T N = 9.691 K watts Now as ηmech = bp / ip = 9.691 / 12.485 = 0.776 = 77.6 %
PROBLEM # 13.2: A two-cylinder, four-stroke gas engine has a bore of 380 mm and a stroke of 585 mm.At 240 rev/min the torque developed is 11.86 kNm. Calculate (i) the bp;(ii) the mean piston speed in m/s;(iii) the bmep.
GIVEN DATA: Two cylinders, four-stroke gas engine. No. of cylinder = n = 2, Dia. Of bore =
TITLE: RECPROCTING INTERNAL COMBUSTION ENGINES
PROBLEM # 13.1:
A quantity governed four-stroke, single-cylinder gas engine has a bore of 146mm and a stroke of 280mm.At 475 rev/min and full load the net load on the friction brake is 433 N, and the torque arm is 0.45 m. The indicator diagram gives a net area of 578 mm² and a length of 70 mm with a spring rating of 0.815 bar per mm. calculate the ip,bp, and mechanical efficiency.
GIVEN DATA:
Four stroke single cylinder gas engine n = no. of cylinders = 1
Dia. of cylinder bore = 146 mm = 0.146 m
Length of stroke = L = 280 mm = 0.28 m
N = 475 revolution/min = 475/ 60 rev/sec. = 7.5416 rev/sec.
Full load, break load = W = B = 433 N
Torque arm = R = 0.45 m
Net area of indicator diagram = 578 mm2 = 578 * 10-6 m2
Length of indicating diagram = 70 mm = 70 * 10 -3 m
Spring rating constt. = 0.815 bar/mm
= 0.815 / 10-3 bar /m = 815 bar/m
REQUIRED:
Indicated power = ip =? Brake power = bp =? ηmech = ?
DIAGRAM:
SOLUTION:
Indicated power is given by ip = (Pi * ALnN)/2 _________________ (1)
This formulae is for 4 stroke engine, But
Pi = indicated pressure =? Pi = (net area of diagram)* constt. / Length of the diagram = 578 * 10-6 * 815/ (70 * 10-3) = 6.73 bar A = Area of the bore = (π/4)* d2 = 0.01674 m2 Now equation (1) becomes ip = 6.73 * 105 * 0.01674 * 0.28 * 7.916 * 1/ 2 = 12485.4 watts = 12.4854 Kwatts
Now T = W * R = 194.85 Nm
bp = 2 π T N = 9.691 K watts Now as ηmech = bp / ip = 9.691 / 12.485 = 0.776 = 77.6 %
PROBLEM # 13.2: A two-cylinder, four-stroke gas engine has a bore of 380 mm and a stroke of 585 mm.At 240 rev/min the torque developed is 11.86 kNm. Calculate (i) the bp;(ii) the mean piston speed in m/s;(iii) the bmep.
GIVEN DATA: Two cylinders, four-stroke gas engine. No. of cylinder = n = 2, Dia. Of bore =