Natural draft wet cooling hyperbolic towers

at Didcot Power Station, UK

An abandoned cooling tower at the derelict

Thorpe Marsh Power Station in Yorkshire,

England.

A mechanical

induced-draft cooling

tower

Cooling towers are heat removal devices used to transfer process

waste heat to the atmosphere. Cooling towers may either use the

evaporation of water to remove process heat and cool the working

fluid to near the wet-bulb air temperature or in the case of "Close

Circuit Dry Cooling Towers" rely solely on air to cool the working

fluid to near the dry-bulb air temperature. Common applications

include cooling the circulating water used in oil refineries,

chemical plants, power stations and building cooling. The towers

vary in size from small roof-top units to very large hyperboloid

structures (as in Image 1) that can be up to 200 metres tall and

100 metres in diameter, or rectangular structures (as in Image 2)

that can be over 40 metres tall and 80 metres long. Smaller towers

are normally factory-built, while larger ones are constructed on

site. They are often associated with nuclear power plants in

popular culture.

A hyperboloid cooling tower was patented by Frederik van Iterson

and Gerard Kuypers in 1918.[1]

1 Classification by use

1.1 HVAC

1.2 Industrial cooling towers

2 Heat transfer methods

3 Air flow generation methods

4 Categorization by air-to-water flow

4.1 Crossflow

4.2 Counterflow

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5 Cooling tower as a flue gas stack

6 Wet cooling tower material balance

7 Cooling towers and Legionnaires' disease

8 Cooling tower fog

9 Cooling tower operation in freezing weather

10 Some commonly used terms in the cooling tower

industry

11 Fire hazards

12 Stability

13 See also

14 References

15 External links

An HVAC cooling tower is a subcategory rejecting heat from a chiller. Water-cooled chillers are normally more

energy efficient than air-cooled chillers due to heat rejection to tower water at or near wet-bulb temperatures.

Air-cooled chillers must reject heat at the dry-bulb temperature, and thus have a lower average reverse-Carnot

cycle effectiveness. Large office buildings, hospitals, and schools typically use one or more cooling towers as

part of their air conditioning systems. Generally, industrial cooling towers are much larger than HVAC towers.

HVAC use of a cooling tower pairs the cooling tower with a water-cooled chiller or water-cooled condenser. A

ton of air-conditioning is the removal of 12,000 Btu/hour (3517 W). The equivalent ton on the cooling tower

side actually rejects about 15,000 Btu/hour (4396 W) due to the heat-equivalent of the energy needed to drive

the chiller's compressor. This equivalent ton is defined as the heat rejection in cooling 3 U.S. gallons/minute

(1,500 pound/hour) of water 10 °F (5.56 °C), which amounts to 15,000 Btu/hour, or a chiller coefficient of

performance (COP) of 4.0. This COP is equivalent to an energy efficiency ratio (EER) of 13.65.

Cooling towers are also used in HVAC systems that have multiple water source heat pumps that share a common

piping "water loop". In this type of system, the water circulating inside the "water loop" removes heat from the

condenser of the heat pumps whenever the heat pumps are working in the cooling mode, then the cooling tower

is used to remove heat from the water loop and reject it to the atmosphere. When the heat pumps are working in

heating mode, the condensers draw heat out of the loop water and reject it into the space to be heated.

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Industrial cooling towers can be used to remove heat from

various sources such as machinery or heated process material.

The primary use of large, industrial cooling towers is to remove

the heat absorbed in the circulating cooling water systems used

in power plants, petroleum refineries, petrochemical plants,

natural gas processing plants, food processing plants,

semi-conductor plants, and for other industrial facilities such as

in condensers of distillation columns, for cooling liquid in

crystallization, etc.[2] The circulation rate of cooling water in a

typical 700 MW coal-fired power plant with a cooling tower

amounts to about 71,600 cubic metres an hour (315,000 U.S.

gallons per minute)[3] and the circulating water requires a

supply water make-up rate of perhaps 5 percent (i.e., 3,600 cubic metres an hour).

If that same plant had no cooling tower and used once-through cooling water, it would require about 100,000

cubic metres an hour [4] and that amount of water would have to be continuously returned to the ocean, lake or

river from which it was obtained and continuously re-supplied to the plant. Furthermore, discharging large

amounts of hot water may raise the temperature of the receiving river or lake to an unacceptable level for the

local ecosystem. Elevated water temperatures can kill fish and other aquatic organisms. (See thermal pollution.)

A cooling tower serves to dissipate the heat into the atmosphere instead and wind and air diffusion spreads the

heat over a much larger area than hot water can distribute heat in a body of water. Some coal-fired and nuclear

power plants located in coastal areas do make use of once-through ocean water. But even there, the offshore

discharge water outlet requires very careful design to avoid environmental problems.

Petroleum refineries also have very large cooling tower systems. A typical large refinery processing 40,000

metric tonnes of crude oil per day (300,000 barrels (48,000 m3) per day) circulates about 80,000 cubic metres of

water per hour through its cooling tower system.

The world's tallest cooling tower is the 200 metre tall cooling tower of Niederaussem Power Station.

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Mechanical draft crossflow cooling tower

used in an HVAC application

With respect

to the heat

transfer

mechanism

employed, the

main types

are:

Wet

cooling towers or simply open circuit cooling towers operate on the principle of evaporation. The

working fluid and the evaporated fluid (usually H2O) are one and the same.

Dry Cooling Towers operate by heat transfer through a surface that separates the working fluid from

ambient air, such as in a tube to air heat exchanger, utilizing convective heat transfer. They do not use

evaporation.

Fluid coolers or Closed Circuit Cooling Towers are hybrids that pass the working fluid through a tube

bundle, upon which clean water is sprayed and a fan-induced draft applied. The resulting heat transfer

performance is much closer to that of a wet cooling tower, with the advantage provided by a dry cooler

of protecting the working fluid from environmental exposure and contamination.

In a wet cooling tower (or Open Circuit Cooling Tower), the warm water can be cooled to a temperature lower

than the ambient air dry-bulb temperature, if the air is relatively dry. (see: dew point and psychrometrics). As

ambient air is drawn past a flow of water, an small portion of the water evaporate, the energy required by that

portion of the water to evaporate is taken from the remaining mass of water reducing his temperature

(aproximately by 970 BTU for each pound of evaporated water). Evaporation results in saturated air conditions,

lowering the temperature of the water process by the tower to a value close to wet bulb air temperature, which

is lower than the ambient dry bulb air temperature, the difference determined by the humidity of the ambient air.

To achieve better performance (more cooling), a medium called fill is used to increase the surface area and the

time of contact between the air and water flows. Splash fill consists of material placed to interrupt the water

flow causing splashing. Film fill is composed of thin sheets of material (usually PVC) upon which the water

flows. Both methods create increased surface area and time of contact between the fluid (water) and the gas

(air).

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A forced draft cooling tower

With respect to drawing air through the tower, there are three types of

cooling towers:

Natural draft, which utilizes buoyancy via a tall chimney. Warm,

moist air naturally rises due to the density differential to the dry,

cooler outside air. Warm moist air is less dense than drier air at the

same pressure. This moist air buoyancy produces a current of air

through the tower.

Mechanical draft, which uses power driven fan motors to force or

draw air through the tower.

Induced draft: A mechanical draft tower with a fan at the

discharge which pulls air through tower. The fan induces

hot moist air out the discharge. This produces low entering

and high exiting air velocities, reducing the possibility of recirculation in which discharged air

flows back into the air intake. This fan/fin arrangement is also known as draw-through. (see

Image 2, 3)

Forced draft: A mechanical draft tower with a blower type fan at the intake. The fan forces air

into the tower, creating high entering and low exiting air velocities. The low exiting velocity is

much more susceptible to recirculation. With the fan on the air intake, the fan is more susceptible

to complications due to freezing conditions. Another disadvantage is that a forced draft design

typically requires more motor horsepower than an equivalent induced draft design. The forced

draft benefit is its ability to work with high static pressure. They can be installed in more

confined spaces and even in some indoor situations. This fan/fill geometry is also known as

blow-through. (see Image 4)

Fan assisted natural draft. A hybrid type that appears like a natural draft though airflow is assisted by a

fan.

Hyperboloid (a.k.a. hyperbolic) cooling towers (Image 1) have become the design standard for all natural-draft

cooling towers because of their structural strength and minimum usage of material. The hyperboloid shape also

aids in accelerating the upward convective air flow, improving cooling efficiency. They are popularly associated

with nuclear power plants. However, this association is misleading, as the same kind of cooling towers are often

used at large coal-fired power plants as well. Similarly, not all nuclear power plants have cooling towers, instead

cooling their heat exchangers with lake, river or ocean water.

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Crossflow is a design in which the air flow is directed perpendicular to the water flow (see diagram below). Air

flow enters one or more vertical faces of the cooling tower to meet the fill material. Water flows (perpendicular

to the air) through the fill by gravity. The air continues through the fill and thus past the water flow into an open

plenum area. A distribution or hot water basin consisting of a deep pan with holes or nozzles in the bottom is

utilized in a crossflow tower. Gravity distributes the water through the nozzles uniformly across the fill material.

In a counterflow design the air flow is directly opposite to the water flow (see diagram below). Air flow first

enters an open area beneath the fill media and is then drawn up vertically. The water is sprayed through

pressurized nozzles and flows downward through the fill, opposite to the air flow.

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Common to both designs:

The interaction of the air and water flow allow a partial equalization and evaporation of water.

The air, now saturated with water vapor, is discharged from the cooling tower.

A collection or cold water basin is used to contain the water after its interaction with the air flow.

Both crossflow and counterflow designs can be used in natural draft and mechanical draft cooling towers.

At some modern power stations, equipped with flue gas purification like the Power Station Staudinger

Grosskrotzenburg and the Power Station Rostock, the cooling tower is also used as a flue gas stack (industrial

chimney). At plants without flue gas purification, problems with corrosion may occur.

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Base of a cooling tower with falling

water

Quantitatively, the material balance around a wet, evaporative cooling

tower system is governed by the operational variables of makeup flow

rate, evaporation and windage losses, draw-off rate, and the

concentration cycles:[5]

M= Make-up water in m3/h

C= Circulating water in m3/h

D= Draw-off water in m3/h

E= Evaporated water in m3/h

W= Windage loss of water in m3/h

X= Concentration in ppmw (of any completely soluble salts ... usually chlorides)

XM= Concentration of chlorides in make-up water (M), in ppmw

XC= Concentration of chlorides in circulating water (C), in ppmw

Cycles= Cycles of concentration = XC / XM (dimensionless)

ppmw= parts per million by weight

In the above sketch, water pumped from the tower basin is the cooling water routed through the process coolers

and condensers in an industrial facility. The cool water absorbs heat from the hot process streams which need to

be cooled or condensed, and the absorbed heat warms the circulating water (C). The warm water returns to the

top of the cooling tower and trickles downward over the fill material inside the tower. As it trickles down, it

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contacts ambient air rising up through the tower either by natural draft or by forced draft using large fans in the

tower. That contact causes a small amount of the water to be lost as windage (W) and some of the water (E) to

evaporate. The heat required to evaporate the water is derived from the water itself, which cools the water back

to the original basin water temperature and the water is then ready to recirculate. The evaporated water leaves

its dissolved salts behind in the bulk of the water which has not been evaporated, thus raising the salt

concentration in the circulating cooling water. To prevent the salt concentration of the water from becoming too

high, a portion of the water is drawn off (D) for disposal. Fresh water makeup (M) is supplied to the tower basin

to compensate for the loss of evaporated water, the windage loss water and the draw-off water.

A water balance around the entire system is:

M = E + D + W

Since the evaporated water (E) has no salts, a chloride balance around the system is:

M (XM) = D (XC) + W (XC) = XC (D + W)

and, therefore:

XC / XM = Cycles of concentration = M ÷ (D + W) = M ÷ (M – E) = 1 + [E ÷ (D + W)]

From a simplified heat balance around the cooling tower:

E = C · ΔT · cp ÷ HV

where: 

HV= latent heat of vaporization of water = ca. 2260 kJ / kg

ΔT= water temperature difference from tower top to tower bottom, in °C

cp= specific heat of water = ca. 4.184 kJ / (kg °C)

Windage (or drift) losses (W) from large-scale industrial cooling towers, in the absence of manufacturer's data,

may be assumed to be:

W = 0.3 to 1.0 percent of C for a natural draft cooling tower without windage drift eliminators

W = 0.1 to 0.3 percent of C for an induced draft cooling tower without windage drift eliminators

W = about 0.005 percent of C (or less) if the cooling tower has windage drift eliminators

Cycles of concentration represents the accumulation of dissolved minerals in the recirculating cooling water.

Draw-off (or blowdown) is used principally to control the buildup of these minerals.

The chemistry of the makeup water including the amount of dissolved minerals can vary widely. Makeup waters

low in dissolved minerals such as those from surface water supplies (lakes, rivers etc.) tend to be aggressive to

metals (corrosive). Makeup waters from ground water supplies (wells) are usually higher in minerals and tend to

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Cooling tower and water discharge of

a nuclear power plant

be scaling (deposit minerals). Increasing the amount of minerals present in the water by cycling can make water

less aggressive to piping however excessive levels of minerals can cause scaling problems.

As the cycles of concentration increase the water may not be able to hold the minerals in solution. When the

solubility of these minerals have been exceeded they can precipitate out as mineral solids and cause fouling and

heat exchange problems in the cooling tower or the heat exchangers. The temperatures of the recirculating

water, piping and heat exchange surfaces determine if and where minerals will precipitate from the recirculating

water. Often a professional water treatment consultant will evaluate the makeup water and the operating

conditions of the cooling tower and recommend an appropriate range for the cycles of concentration. The use of

water treatment chemicals, pretreatment such as water softening, pH adjustment, and other techniques can

affect the acceptable range of cycles of concentration.

Concentration cycles in the majority of cooling towers usually range from 3 to 7. In the United States the

majority of water supplies are well waters and have significant levels of dissolved solids. On the other hand one

of the largest water supplies, New York City, has a surface supply quite low in minerals and cooling towers in

that city are often allowed to concentrate to 7 or more cycles of concentration.

Besides treating the circulating cooling water in large industrial cooling tower systems to minimize scaling and

fouling, the water should be filtered and also be dosed with biocides and algaecides to prevent growths that

could interfere with the continuous flow of the water.[5] For closed loop evaporative towers, corrosion inhibitors

may be used, but caution should be taken to meet local environmental regulations as some inhibitors use

chromates.

Ambient conditions dictate the efficiency of any given tower due to the amount of water vapor the air is able to

absorb and hold, as can be determined on a psychrometric chart.

Further information: Legionellosis and Legionella

Another very important reason for using biocides in cooling towers is

to prevent the growth of Legionella, including species that cause

legionellosis or Legionnaires' disease, most notably L.

pneumophila.

[6] The various Legionella species are the cause of

Legionnaires' disease in humans and transmission is via exposure to

aerosols—the inhalation of mist droplets containing the bacteria.

Common sources of Legionella include cooling towers used in open

recirculating evaporative cooling water systems, domestic hot water

systems, fountains, and similar disseminators that tap into a public

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water supply. Natural sources include freshwater ponds and creeks.

French researchers found that Legionella spread through the air up to 6 kilometres from a large contaminated

cooling tower at a petrochemical plant in Pas-de-Calais, France. That outbreak killed 21 of the 86 people that

had a laboratory-confirmed infection.[7]

Drift (or windage) is the term for water droplets of the process flow allowed to escape in the cooling tower

discharge. Drift eliminators are used in order to hold drift rates typically to 0.001%-0.005% of the circulating

flow rate. A typical drift eliminator provides multiple directional changes of airflow while preventing the escape

of water droplets. A well-designed and well-fitted drift eliminator can greatly reduce water loss and potential for

Legionella or other chemical exposure.

Many governmental agencies, cooling tower manufacturers and industrial trade organizations have developed

design and maintenance guidelines for preventing or controlling (by using Neosens FS sensor for example, the

growth of Legionella in cooling towers. Below is a list of sources for such guidelines:

Centers for Disease Control and PreventionPDF (1.35 MB) - Procedure for Cleaning Cooling Towers and

Related Equipment (pages 239 and 240 of 249)

Cooling Technology InstitutePDF (240 KB) - Best Practices for Control of Legionella, July, 2006

Association of Water TechnologiesPDF (964 KB) - Legionella 2003

California Energy CommissionPDF (194 KB) - Cooling Water Management Program Guidelines For Wet

and Hybrid Cooling Towers at Power Plants

SPX Cooling TechnologiesPDF (119 KB) - Cooling Towers Maintenance Procedures

SPX Cooling TechnologiesPDF (789 KB) - ASHRAE Guideline 12-2000 - Minimizing the Risk of

Legionellosis

SPX Cooling TechnologiesPDF (83.1 KB) - Cooling Tower Inspection Tips {especially page 3 of 7}

PERFECT Cooling Towers|109 KB}} - Legionella Control

Tower Tech Modular Cooling TowersPDF (109 KB) - Legionella Control

GE Infrastructure Water & Process Technologies Betz DearbornPDF (195 KB) - Chemical Water

Treatment Recommendations For Reduction of Risks Associated with Legionella in Open Recirculating

Cooling Water Systems

Under certain ambient conditions, plumes of water vapor (fog) can be seen rising out of the discharge from a

cooling tower (see Image 1), and can be mistaken as smoke from a fire. If the outdoor air is at or near saturation,

and the tower adds more water to the air, saturated air with liquid water droplets can be discharged—what is

seen as fog. This phenomenon typically occurs on cool, humid days, but is rare in many climates.

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Cooling towers with malfunctions can freeze during very cold weather. Typically, freezing starts at the corners

of a cooling tower with a reduced or absent heat load. Increased freezing conditions can create growing volumes

of ice, resulting in increased structural loads. During the winter, some sites continuously operate cooling towers

with 40 °F (4 °C) water leaving the tower. Basin heaters, tower draindown, and other freeze protection methods

are often employed in cold climates.

Do not operate the tower unattended.

Do not operate the tower without a heat load. This can include basin heaters and heat trace. Basin

heaters maintain the temperature of the water in the tower pan at an acceptable level. Heat trace is a

resistive element that runs along water pipes located in cold climates to prevent freezing.

Maintain design water flow rate over the fill.

Manipulate airflow to maintain water temperature above freezing point.[8]

Drift - Water droplets that are carried out of the cooling tower with the exhaust air. Drift droplets have

the same concentration of impurities as the water entering the tower. The drift rate is typically reduced

by employing baffle-like devices, called drift eliminators, through which the air must travel after leaving

the fill and spray zones of the tower. Drift can also be reduced by using warmer entering cooling tower

temperatures.

Blow-out - Water droplets blown out of the cooling tower by wind, generally at the air inlet openings.

Water may also be lost, in the absence of wind, through splashing or misting. Devices such as wind

screens, louvers, splash deflectors and water diverters are used to limit these losses.

Plume - The stream of saturated exhaust air leaving the cooling tower. The plume is visible when water

vapor it contains condenses in contact with cooler ambient air, like the saturated air in one's breath fogs

on a cold day. Under certain conditions, a cooling tower plume may present fogging or icing hazards to

its surroundings. Note that the water evaporated in the cooling process is "pure" water, in contrast to the

very small percentage of drift droplets or water blown out of the air inlets.

Blow-down - The portion of the circulating water flow that is removed in order to maintain the amount

of dissolved solids and other impurities at an acceptable level. It may be noted that higher TDS (total

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dissolved solids) concentration in solution results in greater potential cooling tower efficiency. However

the higher the TDS concentration, the greater the risk of scale, biological growth and corrosion.

Leaching - The loss of wood preservative chemicals by the washing action of the water flowing through

a wood structure cooling tower.

Noise - Sound energy emitted by a cooling tower and heard (recorded) at a given distance and direction.

The sound is generated by the impact of falling water, by the movement of air by fans, the fan blades

moving in the structure, and the motors, gearboxes or drive belts.

Approach - The approach is the difference in temperature between the cooled-water temperature and

the entering-air wet bulb temperature (twb). Since the cooling towers are based on the principles of

evaporative cooling, the maximum cooling tower efficiency depends on the wet bulb temperature of the

air. The wet-bulb temperature is a type of temperature measurement that reflects the physical properties

of a system with a mixture of a gas and a vapor, usually air and water vapor

Range - The range is the temperature difference between the water inlet and water exit.

Fill - Inside the tower, fills are added to increase contact surface as well as contact time between air and

water. Thus they provide better heat transfer. The efficiency of the tower also depends on them. There

are two types of fills that may be used:

Film type fill (causes water to spread into a thin film)

Splash type fill (breaks up water and interrupts its vertical progress)

Full-Flow Filtration- Full-flow filtration continuously strains the entire system flow. For example, in a

100-ton system, the flow rate would be roughly 300 gal/min. A filter would be selected to accommodate

the entire 300 gal/min flow rate. In this case, the filter typically is installed after the cooling tower on the

discharge side of the pump. While this is the preferred method of filtration, for higher flow systems, it

may be cost prohibitive.

Side-Stream Filtration- Side-stream filtration, although popular, does not provide complete protection,

but it can be effective. With side-stream filtration, a portion of the water is filtered continuously. This

method works on the principle that continuous particle removal will keep the system clean.

Manufacturers typically package side-stream filters on a skid, complete with a pump and controls. For

high flow systems, this method is cost-effective.

Properly sizing a side-stream filtration system is critical to obtain satisfactory filter performance. There is some

debate over how to properly size the side-stream system. Many engineers size the system to continuously filter

the cooling tower basin water at a rate equivalent to 10% of the total circulation flow rate. For example, if the

total flow of a system is 1,200 gal/min (a 400-ton system), a 120 gal/min side-stream system is specified.

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Ferrybridge power station

Two hyperboloid cooling towers on

Kharkov Power Station #5

Cooling towers which are constructed in whole or in part of combustible materials can support propagating

internal fires. The resulting damage can be sufficiently severe to require the replacement of the entire cell or

tower structure. For this reason, some codes and standards[9] recommend combustible cooling towers be

provided with an automatic fire sprinkler system. Fires can propagate internally within the tower structure

during maintenance when the cell is not in operation (such as for maintenance or construction), and even when

the tower is in operation, especially those of the induced-draft type because of the existence of relatively dry

areas within the towers.[10]

Being very large structures, they are susceptible to wind damage, and

several spectacular failures have occurred in the past. At Ferrybridge

power station on 1 November 1965, the station was the site of a major

structural failure, when three of the cooling towers collapsed due to

vibrations in 85 mph (137 km/h) winds. Although the structures had

been built to withstand higher wind speeds, the shape of the cooling

towers meant that westerly winds were funnelled into the towers

themselves, creating a vortex. Three out of the original eight cooling

towers were destroyed and the remaining five were severely damaged.

The towers were rebuilt and all eight cooling towers were strengthened

to tolerate adverse weather conditions. Building codes were changed to

include improved structural support, and wind tunnel tests introduced

to check tower structures and configuration.

Architectural engineering

Cooling water

Deep lake water cooling

Evaporative cooler

Fossil fuel power plant

HVAC (Heating, ventilating and air conditioning)

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Hyperboloid structure

Mechanical engineering

Power station

Willow Island disaster

1. ^ UK Patent No. 108,863

^ U.S. Environmental Protection Agency (EPA). (1997) Profile of the Fossil Fuel Electric Power

Generation Industry. Washington, D.C. (Report). Document No. EPA/310-R-97-007. p. 79.

2.

^ Cooling System Retrofit Costs EPA Workshop on Cooling Water Intake Technologies, John Maulbetsch,

Maulbetsch Consulting, May 2003

3.

^ Thomas J. Feeley, III, Lindsay Green, James T. Murphy, Jeffrey Hoffmann, and Barbara A. Carney

(2005). "Department of Energy/Office of Fossil Energy’s Power Plant Water Management R&D

Program." U.S. Department of Energy, July 2005.

4.

^ a b Beychok, Milton R. (1967). Aqueous Wastes from Petroleum and Petrochemical Plants (1st Edition

ed.). John Wiley and Sons. LCCN 67019834. (available in many university libraries)

5.

^ Ryan K.J.; Ray C.G. (editors) (2004). Sherris Medical Microbiology (4th Edition ed.). McGraw Hill.

ISBN 0-8385-8529-9.

6.

7. ^ Airborne Legionella May Travel Several Kilometers (access requires free registration)

8. ^ SPX Cooling Technologies: Operating Cooling Towers in Freezing WeatherPDF (1.45 MB)

9. ^ National Fire Protection Association (NFPA). NFPA 214, Standard on Water-Cooling Towers.

10. ^ NFPA 214, Standard on Water-Cooling Towers. Section A1.1

"Perfect Cooling Towers" - includes diagrams - Troubleshooting Cooling Towers

Cooling Towers: Design and Operation Considerations

What is a cooling tower? - Cooling Technology Institute

"Cooling Towers" - includes diagrams - Virtual Nuclear Tourist

"Perfect Cooling Towers" - includes diagrams - Troubleshooting Cooling Towers

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