Question 4 (12 points) A piston with a circular base whose weight is 25 N, as shown in figure 3 below separates two chambers with
a
the same fluid at their base.
A
air B
air
D
50 cm
30 cm
C
25 cm
30 cm
E
water
90 cm

Air enters a gas turbine with two stages of compression and two stages of expansion at 100 kpa and 17°c. this system uses a regenerator as well as reheating and intercooling – the intercooler returns the air to the inlet temperature. the pressure ratio across each compressor is 4 ; 300 kj/kg of heat are added to the air in each combustion chamber; and the regenerator operates perfectly while increasing the temperature of the cold air by 20°c. determine the system’s thermal efficiency. assume isentropic operations for all compressor and the turbine stages and use constant specific heats at room temperature. (0.378)