Question

Air enters a constant-area combustion chamber at a pressure of 101 kPa and a temperature of 70°C with a velocity of 130 m/s. By ignoring the effects of friction, determine the maximum amount of heat that can be transferred to the flow per unit mass of air.

Answer 1

Answer:

451 kj/kg

Explanation:

Velocity = 139m/s

Temperature = 70⁰C

T = 343K

M1 = v/√prt

= 130/√1.4x287x343

= 130/√137817.4

= 130/371.2

= 0.350

T1/To1 = 0.9760

From here we cross multiply and then make To1 the subject of the formula

To1 = T1/0.9760

To1 = 343/0.9760

To1 = 351.43

Then we go to the rayleigh table

At m = 0.35

To1/To* = 0.4389

To* = 351.43/0.4389

= 800k

M2 = 1

Maximum amount of heat

1.005(800-351.43)

= 450.8kj/kg

= 452kj/kg