Figure 8 shows the diesel cycle.
adiabat
adiabat
lecl
ov
rV
Figure 8
The diesel cycle is similar to the Otto cycle used in the four-stroke gasoline engine you have studied, but there are two important differences. First, the fuel is not admitted until the air is fully compressed at point b. Because of the high temperature at the end of the adiabatic compression, the fuel begins to burn spontaneously. There are no spark plugs in a diesel engine. Second, the combustion takes place more slowly, with the fuel represented by line be. The cycle shown for one cylinder of a diesel engine has V = 50 cm^3, r = 21, and Q = 1000 J. These are typical values for a diesel truck. The engine operates with air γ = 1.40 at 25°C and 1.0 atm pressure.
a) Find p, V, and T at each of the four corners ab, c, and d of the cycle. Display your results in the table given on page 15. Show your workings below the table (partial credits will be given for these if the final answers are incorrect.) [6]
b) What is (i) the net work done by the cylinder during one full cycle and (ii) the thermal efficiency of this engine? [4]
d) What is the speed of a diesel engine running at 2400 revolutions per minute? [2]
END OF PART II
