Page 141 - Air and Gas Drilling Manual
P. 141
1
.
161 769 3
r =
= 2 393
s
11 769
.
The specific heat ratio for air is . Chapter 4: Compressors 4-27
k = 14
.
The clearance volume ratio for this compressor is
c = 006
.
With the above values, Equation 4-38 becomes
1
ε = 096 1 − 006 (2393 . −1
.
.
.
)14
v
ε v = 0 910
.
3
The rated volumetric flow rate into the compressor is 900 ft /min. For this
example the compressor is located at 6,000 ft above sea level, thus,
q = 900 acfm
i
With the above terms the theoretical shaft horsepower required to compress the
air moving through the machine is given by Equation 4-35a. Thus, the theoretical
shaft horsepower is
() 31 4 .769 ) (900 ) 161 .769 ()( . (04 )
. ( ) (11
W = 31 . ) 4 −1
˙
s
. (04 ) 229 .17 11 .769
˙
W = 137 .8
s
For this example
ε m = 090
.
and from Equation 4-39, the actual shaft power is
W ˙ as = 137 .8 = 168 .2
. (0 90 ) . (0 910 )
