The cycle XXXXXXXXXXis a conventional constant-volume fuel-air cycle with a compression ratio of 8. The fuel is isooctane, C,H,,, with a lower heating value of 44.4 MJ/kg. The gas state at 1 is T, =...

The cycle 1-2-3-4-5-6-1 is a conventional constant-volume fuel-air cycle with a compression ratio of 8. The fuel is isooctane, C,H,,, with a lower heating value of 44.4 MJ/kg. The gas state at 1 is T, = 300 K, p, = 1 atmosphere with an equivalence ratio of 1.0 and zero residual fraction. The specific volume at state 1 is 0.9 m3/kg air in the mixture. The temperature at the end of compression at state 2 is 600 K.

(a) Find the indicated fuel conversion efliciency and mean effective pressure of this fuel-air cycle model of a spark-ignition engine.

(b) The eficiency of the cycle can be increased by increasing the expansion ratio r, while maintaining the same compression ratio rc (cycle 1-2-3-44-5A-6-1). (This the piston during the expansion stroke. Tabulate your answers. (Note: You are given the initial conditions for the cycle calculation; changing the value of requires only modest changes in the cycle calculation.)

(c) Comment briefly on the effect of increasing the ratio r_e/r_c
above 1.0 with thjj concept on engine eficiency and specific power (power per unit engine weight). Additional calculations are not required