2. 11/22/2010 GTE Company Confidential 2
GTE Wet Compression
• Wet Compression
The addition of water directly to the compressor to increase the
compressor’s efficiency by intercooling the air as the water
evaporates
– Fogging, the other common use of water to augment power, cools the air
prior to entry and thus increases the mass flow of air through the engine,
and thus the power
– In wet compression the evaporating water vapor displaces the air and the
mass flow through the engine remains relatively constant
Water mass flows considerably in excess of that used in fogging are
typical in wet compression
– 2% water to air ratio is approximately 5x more water than would typically be
used in a fogging application
> For a GE 7EA this equates to roughly 85gpm of DI water
• A 6B would use approximately 40 gpm
Wet compression can be used independently of or in conjunction
with inlet fogging
2% water to air ratio typically gives
– 7-9% increase in power
– 1-2% decrease in Heat Rate
3. 11/22/2010 GTE Company Confidential 3
GTE Wet Compression
• Means of implementing Wet Compression
Indirect
– Water injected upstream into the airflow and carried by the
airflow into the turbine
Direct
– Injectors have line of sight view of the IGVs
Plane of
Injection
Direct
Indirect
4. 11/22/2010 GTE Company Confidential 4
GTE Wet Compression
• Indirect Injection
Pros
– Allows use of nozzles that produce
finest droplets
> Typically have low flow capacity
per nozzle requiring significant
numbers of nozzles
– If no other fogging is used then will
provide a significant part of the benefit
that a stand alone fogger/ evaporative
cooler would add
Cons
– Spray carried by the airflow causes
significant wetting of all downstream
surfaces
> In analysis (on right), 30% of the
water hits the walls. May not be
exact but indicative of the
problem
Water hitting wall
5. 11/22/2010 GTE Company Confidential 5
GTE Wet Compression
• Cons (Cont)
– Likely to have wetting of struts and
inner bell mouth with a possibility of
streaming water directly entering the
engine
Need to line the enclosure
downstream of the injectors with
stainless steel due to corrosive
nature of de ionized water
The radial to axial turn into the
engine naturally biases the water
towards the hub and thus
increases likelihood of bell mouth
wetting
Water Spray Distribution
7EA Wet Compression
Spray Array 1
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
16.00
18.00
0 1 2 3 4 5 6 7 8 9
Radial (Decile)
Percent
Mass Percent
6. 11/22/2010 GTE Company Confidential 6
GTE Wet Compression
• GTE Direct Injection
Pros
– Direct line of sight injection
ensures all water reaches
the IGVs without wetting
surfaces
– Radial and tangential
distribution of the water can
be controlled better over
the shorter distance
– Relatively high pressure
nozzles (800-2000psi)
result in relatively fine drop
size distribution
0
10
20
30
40
50
60
0 1 2 3 4 5 6 7 8 9
PercentofMassinaCertainRadialBand
Fractional Radius (0 = Hub, 9 = Shround)
Water Spray Distribution
V94.3a Water Wash
Design 5 Online Full Flow
Mass Percent
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GTE Wet Compression
• Pros (cont.)
– Since the enclosure is not wetted it
does not need cladding
– System includes a GTE Water Wash
for offline wash benefits and online
washing in periods that wet
compression is not deployed
– Derivative of Water Wash technology
that has been used successfully on
100s of units
• Cons
No fogging effect due to the short
residence time of the water in the
air (<10ms)
8. GTE Wet Compression
• Conclusion
GTE wet compression systems benefit from years of
experience building water wash systems using similar
pumps, control systems and nozzle mounting techniques
Line of sight injection allows much better control of the
water distribution and ensures that all water enters the
compressor as fine drops directly from the nozzles
In addition to the wet compression system the skid
includes the existing GTE water wash system which has
repeatedly been shown to be superior to the OEM versions
– Even when not running Wet compression, efficiency and power
gains are realized by having a cleaner compressor improving
the ROI of the system
11/22/2010 GTE Company Confidential 8
