The Brayton cycle.

Question

Common Data for Question 1 & 2

In two air standard cycles – one operating on the Otto and the other on the Brayton cycle – air is isentropically compressed from 300 to 450 K. Heat is added to raise the temperature to 600K in the Otto cycle and to 550 K in the Brayton cycle.

1. If $\eta _{0}$ and h_B are the efficiencies of the Otto and Brayton cycles, the                                             

      (a) $\eta _{0}$ = 0.25, \eta _{B} = 0.18

      (b) \eta _{0} = \eta _{B} = 0.33

      (c) \eta _{0} = 0.5, \eta _{B} = 0.45

      (d) It is not possible to calculate the efficiencies unless the temperature after the expansion is given

 

  2.  If W₀ and W_B are work outputs per units mass, then                                                                     

      (a) W₀ > W_B

      (b) W₀ < W_B

      (c) W₀ = W_B

      (d) it is not possible to calculate the work outputs unless the temperature after expansion is given