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Air at 80 kPa and 127 °C enters an adiabatic diffuser steadily at a rate of 6000 kg/h and leaves at 100 kPa. The velocity of the air stream
Question
Air at 80 kPa and 127 °C enters an adiabatic diffuser steadily at a rate of 6000 kg/h and leaves at 100 kPa. The velocity of the air stream is decreased from 250 m/s to 40 m/s as it passes through the diffuser. Determine
(a) the exit temperature of the air, and
(b) the inlet and exit areas of the diffuser.
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Physics
3 years
2021-07-19T13:53:56+00:00
2021-07-19T13:53:56+00:00 1 Answers
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Answers ( )
Answer:
a) The exit temperature is 430 K
b) The inlet and exit areas are 0.0096 m² and 0.051 m²
Explanation:
a) Given:
T₁ = 127°C = 400 K
At 400 K, h₁ = 400.98 kJ/kg (ideal gas properties table)
The energy equation is:
For a diffuser, w = Δp = 0
The diffuser is adiabatic, q = 0
Replacing:
Where
V₁ = 250 m/s
V₂ = 40 m/s
Replacing:
Using tables, at 431.43 kJ/kg the temperature is 430 K
b) The inlet area is:
The exit area is: