A 4-cylinder gasoline engine has an efficiency of 28% and delivers 180J of work
ID: 1296996 • Letter: A
Question
A 4-cylinder gasoline engine has an efficiency of 28% and delivers 180J of work per cycle per cylinder.Part A: if the engine runs at 25 cycles per second (1500rpm), determine the work done per second.
Part B: what is the total heat input per second from the gasoline?
Part C: if the energy content of gasoline is 130 MJ per gallon, how long does one gallon last? A 4-cylinder gasoline engine has an efficiency of 28% and delivers 180J of work per cycle per cylinder.
Part A: if the engine runs at 25 cycles per second (1500rpm), determine the work done per second.
Part B: what is the total heat input per second from the gasoline?
Part C: if the energy content of gasoline is 130 MJ per gallon, how long does one gallon last?
Part A: if the engine runs at 25 cycles per second (1500rpm), determine the work done per second.
Part B: what is the total heat input per second from the gasoline?
Part C: if the energy content of gasoline is 130 MJ per gallon, how long does one gallon last?
Explanation / Answer
1) Engine fires at 25 cycles/s:
180 J / cycle/ cylinder * 4 cylinders * 25 cycles/second = 18000 J/s
Work = 18000 Joules every second
2) Total heat equals:
18000 J = 28% efficiency so "X" many Joules equals 100% effiicency?
28% / 100% = 18000 / X
solve for X :
X =64285.714 Joules of heat per second
3) 130MJ = 130,000,000 Joules
the engine uses 64285.714 Joules of heat every second so:
130,000,000 J / 64285.714 J = 2022.22 seconds of running time or about 33.7 minutes