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Special Problems for ME 200 – Fall 2009
Special Problems 33, 34, and 35
Due Monday, November 30, 2009
SP33:
A twostage compressor is designed to minimize the work input requirement.
Air flows
through the system and data for air at some locations within the system is shown in the
figure below.
Both compressors can be considered to be adiabatic and pressure drop
across the intercooler can be neglected.
The isentropic efficiency for the first stage of
compression is 90%.
The intercooler rejects heat to a reservoir at 27
C.
Consider
variable specific heats for air.
P
1
= 100 kPa
T
1
= 300 K
P
2
, T
2
P
3
= P
2
T
3
= 340 K
P
4
= 15.4 MPa
T
4
= 750 K
Compressor
Stage 1
Intercooler
Compressor
Stage 2
T
surr
= 27
C
Q
cooler
(a) Determine the amount of heat rejected (kJ/kg)
in the intercooler.
(b) What is the isentropic efficiency of the second stage compressor?
(c) Compute the total entropy generation (kJ/kgK) for the system.
SP34:
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 Spring '08
 GAL

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