Question

In an ideal Brayton cycle, operating with air, the maximum and minimum cycle temperature are 298 K and 850 K respectively. For an optimum pressure ratio corresponding to maximum work output, the thermal efficiency (%) of cycle is, a) 41 b) 65 c) 51 d) 47

Answer 1

Answer:

a)The efficiency =40.78 % or nearly 41%.

Explanation:

Given that

maximum temperature = 850 K

minimum temperature = 298 K

We know that condition for optimum pressure for maximum work out put is given as

$T_2=T_4=\sqrt{T_1\times T_3}$

So

$T_2=T_4=\sqrt{298\times 850}$

$T_2=T_4=503.28 K$

We also know that efficiency of Brayton cycle given

$\eta =1-\dfrac{T_1}{T_2}$

So now by putting the values

$\eta =1-\dfrac{298}{503.28}$

$\eta =0.4078$

So the efficiency =40.78 % or nearly 41%.