www.guntnerus.com
Author
Mike Silverstein
Sr. Sales Engineer
Efficient Air Compression Cooling While
Conserving Water
For many production facilities, compressed air is a critical utility. Much like power,
compressed air is the life blood of the production facility. Many industrial air compressors
require water cooling for efficient operation. Traditionally, evaporative cooling equipment
has been employed to provide such cooling at the expense of dramatic water consumption.
Güntner’s Adiabatic Cooling System with hydroBLU™ technology now gives facility
owners a cooling option that maintains peak efficiency while drastically reducing water
consumption.
With growing concerns of the scarcity of water, rising cost of water, cost of water treatment
and draught conditions, facility owners are focusing on water conservation in order to be
good stewards of the earth. One such facility owner has opted to employ the Adiabatic
Cooling System (ACS) at multiple sites. By using water only on peak days, the ACS cooler
can reduce water consumption to 20% of a conventional water cooled system and reduce
peak energy demand versus a dry system. A system that is wet when you need it and
dry when you don’t, the ACS combines the reliability and ease of use of a dry cooler with
system efficiencies associated with water cooled equipment.
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2
1. Fan unit
2. Dry, finned heat exchanger
3. Air flow
4. Fluid inlet
5. Fluid outlet
6. Water distribution inlet
7. Pre-cooling pad
8. Water outlet (drain)
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4
Guntner U.S. LLC
110 W. Hillcrest Blvd.
Suite 105
Schaumburg, IL 60195
3
6
5
Member of Güntner Group
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1
At peak ambient temperature, the air entering the finned heat exchanger is pre-cooled by wetted cooling pads to a
temperature approaching the wet bulb temperature, without aerosol formation and without applying water to the finned
surface. The pre-cooling process maintains the required leaving fluid temperature at peak ambient conditions.
At one such site, near Montague, CA, an evaluation of energy and water consumption showed the adiabatic cooling
option provides a significant savings in both cost to operate as well as amount of water used. The ACS cooler provides
a 45% savings annually in the cost of electricity and water; and, perhaps more importantly, an 80% water use savings.
Chart 1 depicts the cumulative resource (water and electricity) consumption of the ACS based on weather bin data.
Note the wet hours are limited to only the warmest hours; whereas the evaporative unit (as seen in Chart 2) requires
water use throughout the year. The evaporative unit consumes about 1.3 million gallons of water annually! The ACS in
contrast consumes a fraction of that at about 260,000 gallons annually.
Chart 1:
Annual Resource Consumption of Adiabatic Cooling System
Chart 2:
Annual Resource Consumption of Evaporative Unit
Annual Usage: Evaporative Unit
1,400,000
Hours per Year (hours)
600
1,200,000
500
1,000,000
400
800,000
300
600,000
200
400,000
100
200,000
0
0
13.0
23.0
33.0
43.0
53.0
63.0
73.0
83.0
Dry Hours
Water Use (gal)
93.0
Hours per Year (hours)
Energy Use (kWh)
Cumulative Use (kWh or gallons)
Wet Hours
Wet Hours
Energy Use (kWh)
Water Use (gal)
600
1,400,000
500
1,200,000
1,000,000
400
800,000
300
600,000
200
400,000
100
200,000
0
Cumulative Use (kWh or gallons)
Annual Usage: hydroBLU™ Adiabatic Control
Dry Hours
0
13.0
23.0
33.0
43.0
53.0
63.0
73.0
83.0
93.0
AMBIENT DRY BULB (°F)
AMBIENT DRY BULB (°F)
Through continuous monitoring of system parameters, Güntner’s hydroBLU™ technology determines the precise
amount of water feed needed for maintaining performance. Water feed is precisely controlled and monitored via a high
pulse rate water meter. Water usage is minimized along with eliminating the need for expensive recirculation and water
treatment systems. This effective means of water management through omission of recirculated water sump with its
potential for stagnant water and no use of aerosols helps to mitigate the proliferation of Legionella. Utilizing unique
programmable logic controllers, hydroBLU™ technology controls the system leaving fluid temperature by managing
water distribution through variable water flow and controlling fan speed.
Part of the hydroBLU™ technology , the ACS utilizes electronically commutated (EC) fan motors and the Güntner Motor
Management (GMM) to regulate fan speed and maintain the lowest possible setpoint. With this technology, the energy
consumption is further reduced by utilizing the minimum amount of fan energy necessary to keep the compressor
operating at its peak efficiency.
Through the effective use of intelligent controls, the ACS helps the facility owner to minimize one’s expenses on water
and electricity required to operate the cooling equipment. The cost of water and electricity for this analysis are based
on the values shown in table 1.
Table 1:
Power and Water Rates
Power and Water Rates:
Electricity rate
Demand charge
Water & sewage
Water treatment
$0.08
$10.00
$6.00
$4.00
$
$
$
$
/
/
/
/
kWh
kW / mo.
kgal
kgal
Table 2:
Annual Resource Comsuption Analysis
Model:
Parameter
Adiabatic
Evaporative
Notes
System
Water Control
Fan Motor Control
Adiabatic
Water Priority
ECM Var. Speed
Integral Pump
Energy Priority
NEMA VFD, belt
Design heat rejection
Entering fluid temperature
Leaving fluid temperature (LFT)
Inlet dry bulb temperature
Inlet wet bulb temperature
Btu/hr
°F
°F
°F
°F
2,340,000
111.0
90.0
100.0
75.0
2,340,000
111.0
90.0
100.0
75.0
Design precooled air (switch point)
Quantity of fans
Total fan power, input
Total air flow rate
Minimum fan speed setting
Spray water pump power, input
Water flow rate
°F
kW
gpm
80.0
8
29.6
140,864
10%
0.00
9.2
NA
1
7.5
47,370
25%
1.70
384.0
Minimum LFT setpoint
°F
80.0
80.0
Fan power, annual average
Spray pump pwr., annual avg.
kW
kW
5.4
0.0
1.1
1.7
Cost of fan electricity
Cost of spray pump electricity
USD/yr
USD/yr
$7,312
$0
$1,645
$1,395
TOTAL power, annual avg.
Fan energy
Spray water pump energy
TOTAL energy
TOTAL cost of electricity
Water use hours per year
Water use hours as % of year
Water use
Water evaporation
Chemically treated blowdown
Non-treated water blowdown
Water intake, maximum
Average water intake per year
Water use, cycles of concentration
Water use savings vs evaporative base
Cost of water
ANNUAL water & energy cost
kW
cfm
kW
kWh/yr
kWh/yr
kWh/yr
USD/yr
hours/yr
kgal/yr
kgal/yr
kgal/yr
kgal/yr
gpm
gpm
cycles
USD/yr
USD/yr
5.4
46,997
0
46,997
$7,312
711
8%
261
196
0
65
9.2
0.5
4.0
80%
$1,568
$8,880
2.8
9,311
14,892
24,203
$3,040
8,760
100%
1,320
990
330
0
7.7
2.5
4.0
0%
$13,199
$16,239
By employing the ACS, the facility owner realizes a $7,359 annual savings relative to evaporative cooled equipment.
In addition to the operating savings, the owner experiences the peace of mind of the reliability of the ACS cooler. In
the event of an upset conditions, such as lack of water, a majority of the thermal performance remains intact with the
ACS cooler. Additionally, the ACS cooler does not require auxiliary components such as recirculating pumps or belts for
mechanical drives, which can experience untimely failures causing expensive downtime.
By minimizing the number of hours required to run wet, varying the flow of water required for adiabatic cooling and
utilizing reliable efficient means of varying fan speed, the ACS offers efficient cooling while saving millions of gallons
of water. Facility owners concerned with operating expenses and conservation of natural resources have an option in
the ACS to fulfill their cooling requirements and maintain efficient processes without the massive water consumption
required by evaporative cooling.
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Guntner U.S. LLC
110 W. Hillcrest Blvd. Suite 105
Schaumburg, IL 60195
USA
Phone: + 1 847 781 0900
www.guntnerus.com
Members of Güntner Group
Errors excepted. Subject to technical amendments without prior notice.
ProSpot 101 / V1 / ENG / 11.2016
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