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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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1. Fan unit2. Dry, finned heat exchanger3. Air flow4. Fluid inlet5. Fluid outlet6. Water distribution inlet7. Pre-cooling pad8. Water outlet (drain)

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www.guntnerus.com

Guntner U.S. LLC110 W. Hillcrest Blvd. Suite 105 Schaumburg, IL 60195

Member of Güntner Group

Author

Mike SilversteinSr. Sales Engineer

Chart 1: Annual Resource Consumption of Adiabatic Cooling System

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.

600

500

400

300

200

100

0

1,400,000

1,200,000

1,000,000

800,000

600,000

400,000

200,000

013.0 23.0 33.0 43.0 53.0 63.0 73.0 83.0 93.0

AMBIENT DRY BULB (°F)

Annual Usage: hydroBLU™ Adiabatic Control

Hou

rs p

er Y

ear (

hour

s)

Cum

ulat

ive

Use

(kW

h or

gal

lons

)

Dry Hours Wet Hours Energy Use (kWh) Water Use (gal)

13.0 23.0 33.0 43.0 53.0 63.0 73.0 83.0 93.0

AMBIENT DRY BULB (°F)

600

500

400

300

200

100

0

Hou

rs p

er Y

ear (

hour

s)

1,400,000

1,200,000

1,000,000

800,000

600,000

400,000

200,000

0

Cum

ulat

ive

Use

(kW

h or

gal

lons

)

Annual Usage: Evaporative UnitDry Hours Wet Hours Energy Use (kWh) Water Use (gal)

Chart 2: Annual Resource Consumption of Evaporative Unit

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 rateDemand chargeWater & sewageWater treatment

$0.08 $10.00 $6.00 $4.00

$ / kWh$ / kW / mo.$ / kgal$ / kgal

Model: Adiabatic EvaporativeParameter Notes

SystemWater ControlFan Motor Control

AdiabaticWater PriorityECM Var. Speed

Integral PumpEnergy PriorityNEMA VFD, belt

Design heat rejectionEntering fluid temperatureLeaving fluid temperature (LFT)Inlet dry bulb temperatureInlet wet bulb temperature

Btu/hr°F°F°F°F

2,340,000111.090.0100.075.0

2,340,000111.090.0100.075.0

Design precooled air (switch point)Quantity of fansTotal fan power, inputTotal air flow rateMinimum fan speed settingSpray water pump power, inputWater flow rate

°F kWcfm

kWgpm

80.0829.6140,86410%0.009.2

NA17.547,37025%1.70384.0

Minimum LFT setpoint °F 80.0 80.0Fan power, annual averageSpray pump pwr., annual avg.TOTAL power, annual avg.

kWkWkW

5.40.05.4

1.11.72.8

Fan energySpray water pump energyTOTAL energy

kWh/yrkWh/yrkWh/yr

46,997046,997

9,31114,89224,203

Cost of fan electricityCost of spray pump electricityTOTAL cost of electricity

USD/yrUSD/yrUSD/yr

$7,312$0 $7,312

$1,645 $1,395 $3,040

Water use hours per yearWater use hours as % of yearWater useWater evaporationChemically treated blowdownNon-treated water blowdownWater intake, maximumAverage water intake per yearWater use, cycles of concentrationWater use savings vs evaporative baseCost of water

hours/yr kgal/yrkgal/yrkgal/yrkgal/yrgpmgpmcycles

USD/yr

7118%2611960659.20.54.080%$1,568

8,760100%1,32099033007.72.54.00%$13,199

ANNUAL water & energy cost USD/yr $8,880 $16,239

Table 2: Annual Resource Comsuption Analysis

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. LLC110 W. Hillcrest Blvd. Suite 105Schaumburg, IL 60195USA

Phone: + 1 847 781 0900www.guntnerus.com

Members of Güntner Group

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