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INTRODUCTIONForced draft cooling towers are very similar to induced draft cooling towers.

The primary difference is that the air is blown in at the bottom of the tower andexits at the top. Water distribution problems and recirculation difficultiesdiscourage the use of forced draft cooling tower.

This is a water evaporation water cooling device. The water is pumped to the topof structure and allowed to function or cascade down. Air is blown into the bottomof structure and blows out through the cooling of water.

Cooling towers

Cooling towers are heat removal devices used to transfer process waste heat tothe atmosphere. Cooling towers may either use the evaporation of water toremove process heat and cool the working fluid to near the wet-bulb airtemperature or in the case of closed circuit dry cooling for any purpose.

Common applications include cooling the circulating water used in oil refineriespetrochemical and other chemical plants thermal power stations and !"ACsystems for cooling buildings. Cooling towers vary in si#e from small roof-top unitsto very large hyperboloid structures $as in the ad%acent image& that can be up to'(( meters tall and )(( meters in diameter or rectangular structures $as in *mage+& that can be over ,( meters tall and ( meters long. The hyperboloid coolingtowers are often associated with nuclear power plants although they are also usedto some extent in some large chemical and other industrial plants. Although theselarge towers are very prominent the vast ma%ority of cooling towers are muchsmaller including many units installed on or near buildings to discharge heat fromair conditioning.

*n steam power plants boiler converts water into steam and this steam is used forrotating turbine .The steam exhausted from turbine is again converted into waterby the help of condenser. o we re/uire a secondary source of water that worksas a heat exchanger and converts exhaust steam into hot water. This water can betaken from river. *n case the re/uired amount of water is not available at steampower plant site then we have to face a problem. To overcome this problem ofwater we use cooling tower that cools hot water discharged from condenser andenables it for next operation.

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By the turn of the 20th century, several evaporative methods of recycling cooling water were in usein areas without a suitable water supply, such as urban locations relying on municipal water mains.In areas with available land, the systems took the form of cooling ponds; in areas with limited land,such as in cities, it took the form of cooling towers.

These early towers were positioned either on the rooftops of buildings or as free standing structures,supplied with air by fans or relying on natural airflow. !n !merican engineering te"tbook from#$## described one design as %a circular or rectangular shell of light plate & in effect, a chimneystack much shortened vertically '20 to (0 ft. high) and very much enlarged laterally. !t the top is aset of distributing troughs, to which the water from the condenser must be pumped; from these ittrickles down over %mats% made of wooden slats or woven wire screens, which fill the space withinthe tower.%

There is either open water cooling system where a cooling tower is involvedand therefore the water is open to the surroundings or so called closed cooling

system where the water is cooled by other meaning and all time circulated andreused. We will concentrate here on open cooling loops only. !ere you get anoverview about cooling water systems.

The principal how this cooling water is distributed is more or less the same in allinstallations. There is a cooling tower or a row of them from there a pipenetwork is supplying the cooling water to all the consumers connected to thesystem. uch consumers are heat exchangers of some sort either direct buildin a machine or a heat exchanger where on the one side cooling water isapplied and on the other side the li/uid or gas which has to be cooled down.*n a cooling tower some of the cooling water is evaporated this evaporation iscooling down the remaining cooling water using the effect of the evaporation

heat. "ery simple explained the water needs a certain amount of energy tochange from the li/uid phase $water& to the gas phase $vapor& this energy istaken from the environment $as well the water& and so water is getting colder.*n this pro%ect we want cooling of warm water in this process we use two fans1one motor is used for supply of warm water in cooling tower. Cooling towershave been designed to provide trouble-free service over an extended period oftime. To obtain the design performance it is necessary that the cooling towerbe installed operated and maintained as prescribed in these instructions.

*vaporative cooling towers are still considered the most efficient way of cooling process water atindustrial sites all over the world. +ith economic and ecological factors always an important

consideration, construction and operation of wet cooling towers necessitates the use of efficient fills anddrift eliminators. !s the pioneer of plastic components for cooling tower applications we help ourcustomers to meet their re uirements.

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Types of cooling system.

1. Open cooling system2. Closed cooling system

Open cooling system

In open cooling system, cooling water is open to the atmosphere, mostly in a cooling tower or a row ofcooling towers, where the evaporation is used for the cooling of the water, systems where seawater,river water or bore well water is used for the cooling.

But the problem which has to face in open cooling system is that it takes a large floor area to install itand it is also affected with surrounding and its performance varies with season because it depends uponthe temperature of surrounding air. There is a cooling tower or a row of them from there apipe network is supplying the cooling water to all the consumers connected to thesystem. uch consumers are heat exchangers of some sort either direct build in amachine or a heat exchanger where on the one side cooling water is applied and

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on the other side the li/uid or gas which has to be cooled down.*n a cooling tower some of the cooling water is evaporated this evaporation iscooling down the remaining cooling water using the effect of the evaporationheat. "ery simple explained the water needs a certain amount of energy to

change from the li/uid phase $water& to the gas phase $vapor& this energy is takenfrom the environment $as well the water& and so water is getting colder.

Closed cooling system

In closed cooling system cooling water will not come in contact with the atmosphere and all timemore or less the same water is used, and the cooling of the closed system is done indirect.

In most cooling water systems we are confronted with all the ma-or problems caused by water. Cooling water is needed as the name tells to cool down something or to get rid ofunwanted heat. Air has to be cooled mainly for air conditioning product has to be cooledafter certain heat processes and machines or processes has to be cooled down becausemost machines produce unwanted heat as a side effect which has to be brought down inorder to run the machine properly.

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Classification by use .

1.HVAC cooling tower 2.Industrial cooling tower

HVAC cooling tower .

!n /! 'heating, ventilating, and air conditioning) cooling tower is used to dispose of '%re-ect%)unwanted heat from a chiller. +ater cooled chillers are normally more energy efficient than aircooled chillers due to heat re-ection to tower water at or near wet bulb temperatures. !ir cooledchillers must re-ect heat at the higher dry bulb temperature, and thus have lower average reversearnot cycle effectiveness. 1arge office buildings, hospitals, and schools typically use one or morecooling towers as part of their air conditioning systems. enerally, industrial cooling towers are

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much larger than /! towers.

/! use of a cooling tower pairs the cooling tower with a water cooled chiller or watercooled condenser. ! ton of air conditioning is defined as the removal of #2,000 Btu3hour '4500+). The equivalent ton on the cooling tower side actually re-ects about #5,000 Btu3hour '((00+) due to the additional waste heat e uivalent of the energy needed to drive the chiller6scompressor. This equivalent ton is defined as the heat re-ection in cooling 478 gallons3minute'#,500 pound3hour) of water #0 9: ' 9 ), which amounts to #5,000 Btu3hour, assuming a chiller

coefficient of performance '


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Industrial cooling towers can be used to remove heat from various sources such as machinery orheated process material. The primary use of large, industrial cooling towers is to remove the heatabsorbed 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 coolingli uid in crystalli?ation, etc. The circulation rate of cooling water in a typical A00 + coal fired

power plant with a cooling tower amounts to about A#, 00 cubic meters an hour '4#5,000 7.8.gallons per minute) and the circulating water re uires a supply water make up rate of perhaps 5

percent 'i.e., 4, 00 cubic meters an hour). If that same plant had no cooling tower and used once-t roug cooling water, it would re uire

about #00,000 cubic meters an hour and that amount of water would have to be continuouslyreturned to the ocean, lake or river from which it was obtained and continuously re supplied tothe plant. :urthermore, discharging large amounts of hot water may raise the temperature of the>eceiving >iver or lake to an unacceptable level for the local ecosystem. *levated watertemperatures can kill fish and other a uatic organisms 'see thermal pollution ). ! cooling towerserves to dissipate the heat into the atmosphere instead and wind and air diffusion spreads theheat over a much larger area than hot water can distribute heat in a body of water. 8ome coalfired and nuclear power plants located in coastal areas do make use of once through ocean water.But even there, the offshore discharge water outlet re uires very careful design to avoidenvironmental problems.

=etroleum refineries also have very large cooling tower systems. ! typical large refinery processing (0,000 metric tons of crude oil per day '400,000 barrels '(C,000 m 4) per day)circulates about C0,000 cubic meters of water per hour through its cooling tower system.

The world6s tallest cooling tower is the 202 meters tall cooling tower of Dalichanda Thermal

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=ower =lant in Eacamar, >a-asthan, India. F

In steam power plants, boiler converts water into steam and this steam is used for rotatingturbine .The steam e"hausted from turbine is again converted into water by the help ofcondenser. 8o we re uire a secondary source of water that works as a heat e"changer andconverts e"haust steam into hot water. This water can be taken from river. In case the re uiredamount of water is not available at steam power plant site then we have to face a problem. Toovercome this problem of water we use cooling tower that cools hot water discharged fromcondenser and enables it for ne"t operation. If the power plant is ne"t to the sea, a big river, orlarge inland water body it may be done simply by running a large amount of water through thecondensers in a single pass and discharging it back into the sea, lake or river a few degreeswarmer and without much loss from the amount withdrawn. That is the simplest method. Thewater may be salt or fresh. 8ome small amount of evaporation will occur off site due to thewater being a few degrees warmer. If the power plant does not have access to abundant water,

cooling may be done by passing the steam through the condenser and then using a coolingwater.

AIM OF PROJ CT

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The pro%ect aims at making a cooling tower cheap more powerful with lowmaintenance.

2We use here misting head instead of 3shower head4.

25ue to shower head Water distribution problems and recirculation difficultiesdiscourage the use of forced draft cooling towers. o we use here 6isting head formaking effective water distribution 1 recirculation

*n this pro%ect we want cooling of warm water in this process we use two fans1one motor is used for supply of warm water in cooling tower. Cooling towers havebeen designed to provide trouble-free service over an extended period of time. Toobtain the design performance it is necessary that the cooling tower be installedoperated and maintained as prescribed in these instructions.

7nly persons possessing the skill and experience described herein should attemptto install this e/uipment. 0rior to installation these instructions should be readcarefully by the person who is to install the cooling tower to be certain that itsinstallation operation and maintenance are thoroughly understood. tep-by-stepinstructions contained in this brochure are based on normal installation conditionsonly. Abnormal or unusual combinations of field conditions should be brought tothe attention of 5elta Cooling Towers or its representative prior to installation ofthe e/uipment.. As only water is evaporated the concentration of solids or solved parts such assalts or minerals in the remaining water is increasing all the time during thisprocess. This leads over time as more and more water evaporates to a higherconcentration of solids $T5 & in the water. As higher the T5 in the cooling wateras more likely there will be technical problems in the system such as fouling andscaling .*n order to avoid these technical problems the common method to counter theseproblems is to replace some of the cooling water with fresh water. This is calledblow down or bleeding. *n most systems this happens automatic. There is set athreshold for T5 or conductivity once this limit is reached a blow down valve or ableeding valve is open and drains a certain amount of water which is thenreplaced by the feed water.As an example if the blow down happens at a concentration of '.8(( T5 and thefeed water holds only )(( T5 the overall concentration of the cooling water willbe lowered. What next to all users of a cooling water system are doing today theyare adding chemicals in the cooling water. There are chemicals against scaling orfouling there are chemicals against corrosion and in most cooling systems alsochemicals against bio activities in the water. *n most cases we see in the fieldthere is a cocktail out of all three ma%or used chemicals added to the cooling waterwhich gives significant cost and effort. There are the costs of the chemicals itselfthe dosing e/uipment with its sensors and control units as well there are the costs

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of logistic to get supplied with the chemicals to store them and bring them to allthe dosing points in the system.

#e$t tr$ns%er &et'o(s

With respect to the heat transfer mechanism employed the main typesare9

Dr) *ooling towers

5ry cooling towers operate by heat transfer through a surface that separatesthe working fluid from ambient air such as in a tube to air heat exchangerutili#ing convective heat transfer. They do not use evaporation.

+et *ooling towers or o,en *ir*-it *ooling towers

Wet cooling towers operate on the principle of evaporative cooling. The workingfluid and the evaporated fluid $usually water& are one and the same.

Fl-i( *oolers or *lose( *ir*-it *ooling towers

Closed circuit cooling towers are hybrids that pass the working fluid through atube 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 coolingtower with the advantage provided by a dry cooler of protecting the workingfluid from environmental exposure and contamination.

*n a wet cooling tower $or open circuit cooling tower& the warm water can becooled to a temperature lower than the ambient air dry-bulb temperature if the airis relatively dry $see dew point and psychometrics&. As ambient air is drawn past aflow of water a small portion of the water evaporates and the energy re/uired toevaporate that portion of the water is taken from the remaining mass of waterthus reducing its temperature. Approximately :;( vaporation results in saturated airconditions lowering the temperature of the water processed by the tower to avalue close to wet-bulb temperature which is lower than the ambient dry-bulbtemperature the difference determined by the initial humidity of the ambient air.

To achieve better performance $more cooling& a medium called fill is used toincrease 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 0"C& upon which the waterflows.


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Cooling +$ter Tre$t&ent /

Cooling water is needed as the name tells to cool down something or to get rid ofunwanted heat. Air has to be cooled mainly for air conditioning product has tobe cooled after certain heat processes and machines or processes has to becooled down because most machines produce unwanted heat as a side effectwhich has to be brought down in order to run the machine properly.

There is either open water cooling system where a cooling tower is involvedand therefore the water is open to the surroundings or so called closed coolingsystem where the water is cooled by other meaning and all time circulated andreused. We will concentrate here on open cooling loops only. !ere you get anoverview about cooling water systems.

The principal how this cooling water is distributed is more or less the same inall installations. There is a cooling tower or a row of them from there a pipenetwork is supplying the cooling water to all the consumers connected to thesystem. uch consumers are heat exchangers of some sort either direct buildin a machine or a heat exchanger where on the one side cooling water isapplied and on the other side the li/uid or gas which has to be cooled down.*n a cooling tower some of the cooling water is evaporated this evaporation iscooling down the remaining cooling water using the effect of the evaporationheat. "ery simple explained the water needs a certain amount of energy tochange from the li/uid phase $water& to the gas phase $vapor& this energy istaken from the environment $as well the water& and so water is getting colder.As only water is evaporated the concentration of solids or solved parts such assalts or minerals in the remaining water is increasing all the time during thisprocess. This leads over time as more and more water evaporates to a higherconcentration of solids $T5 & in the water. As higher the T5 in the coolingwater as more likely there will be technical problems in the system *n order toavoid these technical problems the common method to counter theseproblems is to replace some of the cooling water with fresh water. This is calledblow down or bleeding. *n most systems this happen automatic. There is set athreshold for T5 or conductivity once this limit is reached a blow down valveor a bleeding valve is open and drains a certain amount of water.As an example if the blow down happens at a concentration of '.8(( T5 andthe feed water holds only )(( T5 the overall concentration of the coolingwater will be lowered. What next to all users of a cooling water system aredoing today they are adding chemicals in the cooling water. There arechemicals against scaling or fouling there are chemicals against corrosion andin most cooling systems also chemicals against bio activities in the water. *nmost cases we see in the field there is a cocktail out of all three ma%or usedchemicals added to the cooling water which gives significant cost and effort.

There are the costs of the chemicals itself the dosing e/uipment with itssensors and control units as well there are the costs of logistic to get suppliedwith the chemicals to store them and bring them to all the dosing points in thesystem. +$ter tre$t&ent

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$%OC& !IA'#A(

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+OR IN8 OF PROJ CT/*n forced draft cooling tower warm water from the condenser are sprayed throughspray header in the form of fine droplet shower. hower spread the stream ofwater so that more water come in contact with air. A fan which is at the bottomside of tower forces the air inside the tower. When air comes in contact with waterit becomes saturated by releasing its latent heat. This saturated air flows frombottom to top and during this period it absorbs the sensible heat of water andwater is cooled till it reaches to bottom of tower.

Cooling towers have been designed to provide trouble-free service over anextended period of time. All Cooling Towers operate on the principle of removingheat from water by evaporating a small portion of the water that is re-circulatedthrough the unit.

The heat that is removed is called the latent heat of vapori#ation. >ach one poundof water that is evaporated removes approximately ) ((( stablishment of the approach fixes the operating temperature of the tower andis the most important parameter in determining both tower si#e and cost.

,. Dri%t - Water droplets that are carried out of the cooling tower with the exhaustair. 5rift loss does not include water lost by evaporation. 0roper tower designcan minimi#e drift loss. The drift rate is typically reduced by employing baffle-like devices called drift eliminators through which the air must travel afterleaving the fill and spray #ones of the tower.

8. #e$t o$( - The amount of heat to be removed from the circulating waterwithin the tower. !eat load is e/ual to water circulation rate $gem& times thecooling range times 8(( and is expressed in


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;. +et -l< Te&,er$t-re 9+ T: - The lowest temperature that watertheoretically can reach by evaporation. Wet-


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The intake louvers are an arrangement of hori#ontal blades at the air inlets thatprevent escape of falling water while allowing the entry of air.

All Cooling Towers operate on the principle of removing heat from water byevaporating a small portion of the water that is re-circulated through the unit.

The heat that is removed is called the l$tent 'e$t o% ?$,ori@$tion/>ach one pound of water that is evaporated removes approximately ) (((


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COMPON NT0 D 0CRIPTION

1. STRUCTURE SIZE.

0ro%ect structure si#e is ,,C6 B(C6 .


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An electric motor uses electrical energy to produce mechanical energy verytypically through the interaction of magnetic fields and current-carryingconductors. The reverse process producing electrical energy from mechanicalenergy is accomplished by a generator or dynamo. 6any types of electric motors

can be run as generators and vice versa. For example a starter generator for a gasturbine or Traction motors used on vehicles often performs both tasks.

>lectric motors are found in applications as diverse as industrial fans blowers andpumps machine tools household appliances power tools and disk drives. Theymay be powered by direct current $for example a battery powered portable deviceor motor vehicle& or by alternating current from a central electrical distributiongrid. The smallest motors may be found in electric wristwatches. 6edium-si#emotors of highly standardi#ed dimensions and characteristics provide convenientmechanical power for industrial uses. The very largest electric motors are used forpropulsion of large ships and for such compressors with ratings in the millions of

watts. >lectric motors may be classified by the source of electric power by theirinternal construction by their application or by the type of motion they give.

The physical principle of production of mechanical force by the interactions of anelectric current and a magnetic field was known as early as ) '). >lectric motorsof increasing efficiency were constructed throughout the ):th century butcommercial exploitation of electric motors on a large scale re/uired efficientelectrical generators and electrical distribution networks.

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ome devices such as magnetic solenoids and loudspeakers although theygenerate some mechanical power are not generally referred to as electric motorsand are usually termed actuators and transducers respectively.

DC Motors

A 5C motor is designed to run on 5C electric power. Two examples of pure 5Cdesigns are 6ichael Faraday ?s homopolar motor $which is uncommon& and the ballbearing motor which is $so far& a novelty.


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AC /MOTOR/

*n ) ' Gikola Tesla discovered the rotating magnetic field and pioneered the useof a rotary field of force to operate machines. !e exploited the principle to design auni/ue two-phase induction motor in ) +. *n ) 8 Lalileo Ferraris independentlyresearched the concept. *n ) Ferraris published his research in a paper to theDoyal Academy of ciences in Turin.

Tesla had suggested that the commutates from a machine could be removed andthe device could operate on a rotary field of force. 0rofessor 0aschal histeacher stated that would be akin to building a perpetual motion machine.

Tesla would later attain U.S. Patent 0,416,194 >lectric 6otor $5ecember

) :& which resembles the motor seen in many of Tesla?s photos. This classicalternating current electro-magnetic motor was an induction motor.

Stepper motors

Closely related in design to three-phase AC synchronous motors are steppermotors where an internal rotor containing permanent magnets or a magnetically-soft rotor with salient poles is controlled by a set of external magnets that areswitched electronically. A stepper motor may also be thought of as a crossbetween a 5C electric motor and a rotary solenoid. M !n electric motor uses electricalenergy to produce mechanical energy, very typically through the interaction of magnetic fields and

current carrying conductors. The reverse process, producing electrical energy from mechanical energy,is accomplished by a generator or dynamo. any types of electric motors can be run as generators, andvice versa. :or e"ample a starter3generator for a gas turbine or Traction motors used on vehicles often

performs both tasks.

*lectric motors are found in applications as diverse as industrial fans, blowers and pumps, machinetools, household appliances, power tools, and disk drives. They may be powered by direct current 'fore"ample a battery powered portable device or motor vehicle), or by alternating current from a centralelectrical distribution grid. The smallest motors may be found in electric wristwatches. edium si?emotors of highly standardi?ed dimensions and characteristics provide convenient mechanical power forindustrial uses. The very largest electric motors are used for propulsion of large ships, and for such

compressors, with ratings in the millions of watts. *lectric motors may be classified by the source ofelectric power, by their internal construction, by their application, or by the type of motion they give.

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Co&,onents o% &otor/

A typical AC motor consists of two parts9

An outside stationary stator having coils supplied with AC current to producea rotating magnetic field andN

An inside rotor attached to the output shaft that is given a tor/ue by therotating field.

Torque motors

A tor/ue motor $also known as a limited tor/ue motor& is a speciali#ed form ofinduction motor which is capable of operating indefinitely while stalled that iswith the rotor blocked from turning without incurring damage. *n this mode ofoperation the motor will apply a steady tor/ue to the load $hence the name&.

Slip ring

The slip ring is a component of the wound rotor motor as an induction machine$best evidenced by the construction of the common automotive alternator& wherethe rotor comprises a set of coils that are electrically terminated in slip rings .

These are metal rings rigidly mounted on the rotor and combined with brushes $asused with commutates& provide continuous unstitched connection to the rotorwindings.

$ lip rings are most-commonly used in automotive alternators as well as insynchronic angular data-transmission devices among other applications.&

The slip ring motor is used primarily to start a high inertia load or a load thatre/uires a very high starting tor/ue across the full speed range.


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When used with a load that has a tor/ue curve that increases with speed themotor will operate at the speed where the tor/ue developed by the motor is e/ualto the load tor/ue. Deducing the load will cause the motor to speed up andincreasing the load will cause the motor to slow down until the load and motortor/ue are e/ual. 7perated in this manner the slip losses are dissipated in the

secondary resistors and can be very significant. The speed regulation and netefficiency is also very poor.

To calculate a motor?s efficiency the mechanical output power is divided by theelectrical input power9

where O is energy conversion efficiency Pe is electrical input power and Pm ismechanical output power.

*n simplest case Pe K VI and Pm K T P where V is input voltage I is input current Tis output tor/ue and P is output angular velocity. *t is possible to deriveanalytically the point of maximum efficiency. *t is typically at less than ) ' the stalltor/ue. *mplications


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spaces and even in some indoor situations. This fan fill geometry is also known asblow-through . $ ee *mage ,&

Cooling fans and blowers provide cooling solutions to your system thermal

problems. The need for forced-air cooling by using an AC or 5C axial fan or blowershould be determined at an early stage in the system design. *t is important thatthe design plans for good airflow to heat-generating components and allowsade/uate space and power for the cooling fan or blower.

F$nsB Dri?es $n( Motors

Cooling tower components operate in a moisture laden air. Lenerally speaking theinterior temperature of cooling tower is )(( QF at )((R D!. =nder these conditionsthe drive components particularly the fan motors and gear drives must be totallyenclosed for trouble free operation.

). 0,ee( Re(-*ers - The speed reducer shall be rated in accordance withpractices of the American Lear 6anufacturer?s Association $AL6A& using acooling tower service factor of greater than '. The life span of intermediatebearings for input shafts shall be 8( ((( hours or more $I)( life2& and

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bearings for output shafts shall be )(( ((( hours or more $I)( life2&. 2 I)(life defines the basic rated life when :(R of a group of identical bearingswill exceed this life when rotated at the same speed and under the sameload and operating conditions. Datings shall also be in accordance with CT*T5-))). Lear reducers shall be of the spiral bevel single $or double&

reduction type. The gear reducer shall be bolted to a

'. tainless steel base plate which in turn is bolted to the cooling towerstructure. addle or bracket type mounting shall not be permitted.

'. F$n Asse&&. The fan hub shall be of !5L steel plateconstruction. A non-corrosive metal spacer sleeve should be provided toprevent the fan from dropping onto the gear reducer in the event of shaftbushing failure.

+. Dri?e Conne*tion - The motor shall be mounted outside the air stream. Thedrive shaft shall be all stainless steel full-floating type with non-lubricatedflexible couplings at both ends. >ach drive shaft coupling shall be provided witha stainless steel guard to prevent damage to the surrounding e/uipment in caseof shaft failure. Composite type drive shaft tubes are permitted.

,. F$n Motors E The motor shall be G>6A standard T>FC enclosure Class Finsulation suitable for corrosive duty. An 750 motor should never be installedfor cooling tower duty. The motor shall be suitable for across line starting. Themotor shall be mounted to a stainless steel base plate and bolted securely tothe fan deck. A cooling tower motor need not be =I listed as the smoke anddebris resulting out of the motor upset condition are not directed to theoccupied spaces. =I listing is therefore not critical.

8. F$n De*= E The fan deck shall be constructed of composite FD0 materialforming a rigid base for mounting the fan speed reducer drive shaft and motor.

B. '$-st F$n 0t$*=s E The exhaust fan stack shall be constructed of compositeFD0 panels by the cooling tower manufacturer. For fan stacks less than B highan easily removable aluminum fan screen shall be provided for safety as astandard.

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A(?$nt$ges o% t'e *o-nter %low (esign

pray water distribution makes the tower more free#e-resistant.


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Common aspects of both designs9

4. PU P!

Pump is used for recirculation the cooled water to spray pipe. For this purposea220 !" pump is used.

Centri%-g$l ,-&,/

A centrifugal pump converts the input power to kinetic energy in the li/uid byaccelerating the li/uid by a revolving device - an impeller. The most common typeis the volute pump. Fluid enters the pump through the eye of the impeller whichrotates at high speed. The fluid is accelerated radially outward from the pumpchasing. A vacuum is created at the impellers eye that continuously draws morefluid into the pump.

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The energy created by the pump is kinetic energy according the /uation. The energy transferred to the li/uid corresponds to the velocity at theedge or vane tip of the impeller. The faster the impeller revolves or the bigger theimpeller is the higher will the velocity of the li/uid energy transferred to the li/uidbe. This is described by the Affinity Iaws.

Press-re $n( 'e$(/

*f the discharge of a centrifugal pump is pointed straight up into the air the fluidwill pumped to a certain height - or head - called the s'-t o%% 'e$( . Thismaximum head is mainly determined by the outside diameter of the pump?simpeller and the speed of the rotating shaft. The head will change as the capacityof the pump is altered.

The kinetic energy of a li/uid coming out of an impeller is obstructed by creatinga resist$n*e in the flow. The first resistance is created by the pump casing whichcatches the li/uid and slows it down. When the li/uid slows down the kineticenergy is converted to pressure energy.

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*here

# efficiency $1&

P in # power input

Pout # power output

".S#ITC$

*n electronics a swit*' is an electrical component that can break an electricalcircuit interrupting the current or diverting it from one conductor to another. Themost familiar form of switch is a manually operated electromechanical device withone or more sets of electrical contacts. >ach set of contacts can be in one of twostates9 either ?closed? meaning the contacts are touching and electricity can flowbetween them or ?open? meaning the contacts are separated and no conducting.

A switch may be directly manipulated by a human as a control signal to a systemsuch as a computer keyboard button or to control power flow in a circuit such as alight switch. Automatically-operated switches can be used to control the motions ofmachines for example to indicate that a garage door has reached its full openposition or that a machine tool is in a position to accept another work piece.witches may be operated by process variables such as pressure temperatureflow current voltage and force acting as sensors in a process and used toautomatically control a system. For example a thermostat is an automatically-operated switch used to control a heating process. A switch that is operated byanother electrical circuit is called a relay. Iarge switches may be remotelyoperated by a motor drive mechanism. ome switches are used to isolate electricpower from a system providing a visible point of isolation that can be pad-locked ifnecessary to prevent accidental operation of a machine during maintenance or toprevent electric shock.

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CO /CTO#0

onnectors are basically used for interface between two. ere we use connectors for havinginterface between = B and C05# icroprocessor Dit.

There are two types of connectors they are male and female. The one, which is with pinsinside, is female and other is male.

These connectors are having bus wires with them for connection.

:or high fre uency operation the average circumference of a coa"ial cable must be limited toabout one wavelength, in order to reduce multimodal propagation and eliminate erratic reflectioncoefficients, power losses, and signal distortion. The standardi?ation of coa"ial connectorsduring +orld +ar II was mandatory for microwave operation to maintain a low reflectioncoefficient or a low voltage standing wave ratio. :or e"ample, a thermostat is an automaticallyoperated switch used to control a heating process. ! switch that is operated by another electricalcircuit is called a relay. 1arge switches may be remotely operated by a motor drive mechanism.8ome switches are used to isolate electric power from a system, providing a visible point ofisolation that can be pad locked if necessary to prevent accidental operation of a machine duringmaintenance, or to prevent electric shock.

In electronics, a connector is an electrical component that can break an electrical circuit,interrupting the current or diverting it from one conductor to another. The most familiar form ofswitch is a manually operated electromechanical device with one or more sets of electricalcontacts. *ach set of contacts can be in one of two states either 6closed6 meaning the contacts aretouching and electricity can flow between them, or 6open6, meaning the contacts are separated

and no conducting.

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$)o-t Consi(er$tions There are two key factors affecting cooling tower performance9 The first is airflowwhich is important as it propagates heat transfer $i.e. with more air available there

is greater potential for heat transfer to occur&. The second is entering wet bulbtemperature. Technically wet bulb temperature is important because any increasein entering air wet bulb temperature will increase the minimum temperature towhich a tower can performN and thus lower its cooling capacity.

Cooling tower layout where and how a tower is sited can significantly impact bothits airflow and entering air wet bulb temperature. 7bstructions to the airflow cancause two problems9

1/ Re*ir*-l$tion

Decirculation is the result of short-circuiting the air flow. Decirculationoccurs when the tower s moist discharge $exhaust plume& is somehowredirected back into the air intake. For example if a tower is located closeto the windward or even leeward side of a taller building wall or otherstructure the potential exists for plume travel downward causing moistair to be drawn to the tower air inlets. The moist air can effectivelyincrease the tower entering air wet bulb temperatureN thereby reducingthe tower capacity. A mere two degree Fahrenheit increase in enteringwet bulb temperature can decrease tower capacity )' to )BR. As anexample a cooling tower selected at ; QF wet bulb needs to be about,(R bigger than the one selected at ;'QF wet bulb Sat :8 in and 8 outM

for e/uivalent performance. For the optimum cooling tower performanceand enhanced safety (.8 to ' QF re-circulation allowance is loaded on thedesign wet bulb temperature. As a rule of thumb recirculation allowanceof (.8 QF for towers smaller than )( ((( L06 and ' QF for towersdesigned for more than )(( ((( L06 are added to the design wet bulbtemperature.

2/ 0t$r?ing

0t$r?ing the tower for air. Cooling tower installation with intake facingtoo close to the wall or any other obstruction will experience airflowrestrictions. This will inhibit the tower s ability to evaporate waterN thusthermal capacity suffers accordingly. For example a tower with an airintake too close to a solid wall would be starved of air. This would result inless evaporationN thereby resulting in reduced tower capacity.

Tower efficiency is also dependent upon the physical placement and orientation ofcooling tower cells at the facility. *f the e/uipment is next to a wall precipitationfrom the tower can cause building wall paint to peel gutters to rust or icicles to

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form. Cooling towers are physically the largest footprint of e/uipment in anindustrial facility or a commercial building. 5ue to the si#e impediments of coolingtowers most are stored outside with ample room for air flow. 0roper location of thecooling tower is essential to its satisfactory operation. Thus the followingrecommendations should be considered9

). elect an open site having an unobstructed air supply and free air motion.6inimum hori#ontal separation distance between cooling towers and outdoor airintakes and other areas where people may be exposed should be considered.

The draft revision of A !DA>-B' ): :D recommends a minimum separation of)8 feet between cooling towers and building intakes.

'. Cooling towers should be installed such that its discharge is at an elevatione/ual to or greater than that of ad%acent structures. This allows the exhaust tobe carried over the ad%acent structure thus minimi#ing the potential for re-entrainment. *t is easily accomplished by simply raising the tower whereby theinstalling contractor can provide supporting steel to elevate the tower to anydesired height. An alternate tactic is to incorporate a tower exhaust stack up toor beyond the level of ad%acent structures.

+. *nterference from other e/uipment especially other towers can raise the localwet bulb temperature from QF to as much as QF above the ambient wet bulbtemperature depending on the si#e $in terms of both dimension and capacity&of the tower. This is particularly true if these are low velocity exhausts. *n orderto maintain the separation of air streams and to avoid air restrictions andrecirculation as a general rule of thumb the well or enclosure should have agross plan area that is at least '.8 to +.( times that of the tower.

,.


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Components of a Cooling Tower

The average life of a cooling tower is estimated at approximately '( yearsand well-maintained towers often can operate well beyond that. 6ost towersare designed such that air moving components and heat transfer media canbe replaced when necessary often resulting in higher unit performance astechnological advances occur in the industry. The key to longevity is keepingthe base structure of the tower usable especially the cold water basin. Theimportant components of the cooling tower and their functions areaddressed below9

1 . P$*=ing M$teri$ls

0acking materials $splash bars fills etc.& are used to enhance performance ofcooling towers by providing increased surface area between air and water.

plash Fills - ome cooling towers have slats of wood or plastic that arehori#ontally and vertically separated in a staggered pattern. These slats areknown as splash fills. !ot water falls onto a cooling tower distribution deckand then splashes down onto the top slats before cascading down to thelower slats. The splashing causes the water to disperse into droplets therebyincreasing the contact of water and air. Treated wood splash bars is stillspecified for wood towers but plastic splash fill promotes better heattransfer and is now widely used where water /uality demands the use ofwider spaced splash fill.

Film Fills - 7ther cooling towers use film fill made of corrugated plasticsheets that have been %oined into blocks with a honeycombed appearance.!ot water falling onto the distribution deck forms a surface film as itchannels through the fill down to the cooling tower basin. 0lastics are widelyused for fill including 0"C polypropylene and other polymers. Film fill offershigher efficiency and is a preferred choice where the circulating water isgenerally free of debris. 5ebris could plug the fill passageways therebyre/uiring higher maintenance and cleaning.

2 . Cooling Tower #ot +$ter Distri


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3 . Cooling Tower Col( +$ter $sin

Cold Water


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5 . Air Inlet 0*reens An air inlet screen is the point of entry for the air into the tower. The inlet maytake up an entire side of a tower-cross-flow design or may be located low on

the side or the bottom of counter-flow designs. Coarse mesh screens should beinstalled over the air intake components of the cooling tower to reduce theingress of coarse debris.

6 . o-?ers Lenerally cross-flow towers have inlet louvers to e/uali#e airflow into the filland retain the water within the tower. 6any counter-flow tower designs do notre/uire louvers.

7 . Dri%t li&in$tors They are an assembly of baffles or labyrinth passages through which the air passesprior to its exit from the tower for the purpose of removing entrained waterdroplets from the exhaust air. The eliminator reduces the drift $to (.(('R or lessdown to (.(((8R& of the circulating water flow. Lenerally the drift eliminators are0"C type )(-mil minimum sheet thicknesses with '8-mil minimum 0"C stiffeners=" protected capable of supporting weight of maintenance workers withoutdamage to the top surface.

!/ $((ers #$n(r$ils Iadders and !andrails for tower access are necessary for large field erectedcooling towers and make sense on some factory assembled designs. A hot dipgalvani#ed steel access door and ladder are necessary in each cell for internalaccess to fill from the fan deck level. These are safety and maintenanceaccessories that are recommended per the guidelines of 7 !A standards. eismicbracing options exist in the in earth/uake prone areas.

"/ Cooling Tower ),$sses


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Cooling Tower M$teri$ls

Cooling tower structures are constructed using a variety of materials. Whilepackage cooling towers are generally constructed with fiberglass galvani#ed steel$or stainless steel in special situations& many possibilities exist for field-erectedstructures. Field-erected towers can be constructed of 5ouglas fir redwoodfiberglass steel or concrete. >ach material has advantages and disadvantages.

1/ +oo( >

*n early days towers were constructed primarily of Dedwood because of itsnatural tendency to inhibit decay. As the Dedwood resources diminished 5ouglas-Fir come into existence. 5ouglas-Fir however supports the growth and proliferationof micro-organisms causing rapid delignification $eating of wood&. "arious methods

of pressure treatment and incising are used to prevent micro-organisms attack towood which includes CCA and ACC treatment. Chromate Copper Arsenate $CCA&was initially used as a preservative but because of its arsenic content Acid CopperChromate $ACC& has replaced it. *rrespective of any treatment the leaching ofchemicals is still a concern to the environment and sometimes extensive additionalwater treatment of blow down and tower sediment is needed. ome drawbacks ofwooden towers are stated below9

U The wooden structure is less durable and its life expectancy is low.5elignification $eating of wood& is controlled by ad%usting the p! strictlybetween ; and ;.8

U The drift losses are over )R.

U The tower has a larger footprint and needs more space when compared toother alternatives.

U Algae formation is a continuous problem in this type of Cooling Tower.

U The wooden structure is less durable.

U The wooden tower usually re/uires a large concrete tank that involves morecost time and labor.

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5/Fi

Currently the fastest growing segment of the cooling tower market is structuresbuilt with pultruded FD0 sections. This inert inorganic material is stronglightweight chemically resistant and able to handle a range of p! values. Fire-

retardant FD0 can eliminate the cost of a fire protection system which can e/ual 8to )'R of the cost of a cooling tower.

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Gote that for the cooling towers erected over a concrete basin height is measuredfrom the elevation of the basin curb. JGominalJ heights are usually measured tothe fan deck elevation not including the height of the fan cylinder. !eights fortowers on which a wood steel or plastic basin is included within the

manufacturer?s scope of supply are generally measured from the lowermost pointof the basin. *n the plastics industry a chilling system cools the hot plastic that isin%ected blown extruded or stamped. A chilling system can also cool down thee/uipment that is used to create plastic products $hydraulics of the moldingmachine gear box and barrel of the extruder that saves on energy and on thewear and tear of the machine itself.


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CAPACIT OF COO IN8 TO+ R/

Capacity of cooling tower depends upon following factors.

). The amount of water surface exposed to air.

'. !eight of the tower.

+. The velocity of Air passing over the droplet of water.

,. Wet bulb temp of atmospheric air.

Therefore for high performance of cooling tower its height should be more 1high velocity air stream must pass over the droplet of water.wet bulb temp of airshould be less. >

Cooling Tower C$,$*it) Controls

7ne may think that lower water temperature from cooling tower dictates theeffectiveness of the cooling tower. Ves this is trueN however some processes canbe adversely affected if the cooling water supply gets too cold. Air-conditioningcentrifugal chillers for instance re/uire a specific minimum entering condenserwater temperature to prevent surging.

*t is very important to maintain close control on the cooling tower during winteroperation. *n order to provide a margin of safety a minimum leaving watertemperature of ,8 @F is recommended.

Degardless of what type of capacity control is utili#ed a full flow bypass may bere/uired. *f the cooling load is to be maintained below +(R of the full wintercapacity then a full flow bypass valve should be incorporated. This valve serves todivert water from the tower hot water distribution system to the cold basin.

Alternatively reducing tower airflow yields higher leaving water temperatures. Fewother control options are listed below9

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The other controls include the automatic ad%ustment of the chemical feed rate tomaintain water chemistry automatic blow-down and the controls for enhancingenergy conservation.

1/ i


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+et;


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Approach is the most important indicator of cooling tower performance. *t dictatesthe theoretical limit to the leaving cold-water temperature. Go matter the si#e ofthe cooling tower range or heat load it is not possible to cool the water below thewet bulb temperature of air.

*t should be noted that when the W


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determine the inlet and outlet water temperatures but not the difference betweenthem.

Summari%ing!Dange K !ot water inlet temperature $!WT& E Cold water outlet temperature $CWT&

Approach K Cold water outlet temperature $CWT& E W


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U 7n restart the sump shall run out of water before it can fill the empty piping.While the make-up valve may eventually add enough water for the system tooperate the pump may become air-bound causing cavitations.

ystem designer must ensure the ade/uate si#e of the basin yet not over si#ingit to minimi#e the drain-back of any water. An easier approach is to locate thecooling tower as the highest element in the system. The tower should beelevated until all other system components are below the overflow level of thecooling tower except for any vertical risers to the tower inlet$s&. When designinga system the designer must perform the hydraulic analysis and calculate theamount of water the basin must accept at pump shutdown. As a general rulethe tank should be si#ed to hold three times the rate of circulation in gallons perminute.

,. All supply and return piping must be independently supported. pacing forpiping and service access should be considered when positioning the coolingtower. Also to ensure an ade/uate positive suction head the pump should belocated below the bottom of the cooling tower sump.

8. The inlet and discharge ducting should be screened to prevent foreign ob%ectsfrom entering.

B. hould prevailing winds blow into a hori#ontal discharge it is recommended thata suitable windbreak be installed several feet away.

;. The tank should be provided with properly si#ed overflow makeup drain andsuction connections. When a sump tank is used the cooling tower should belocated high enough above it to allow free cold water gravity drain.

. When the cooling tower is located outdoors ade/uate measures including theuse of heat tracing tape and insulation should be considered to protect outdoorwater lines from free#ing.

:. 7n multiple tower installations pipe si#ing should balance pressure drops toprovide e/ual inlet pressures. >/uali#ing fittings can be provided in coolingtower sumps and are available as an option from the factory. >ach unit shouldbe valved separately to allow for flow balance or isolation from service.

)(. An inlet pressure gauge should be installed immediately before the coolingtower inlet connection.

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)). The makeup connection should be provided with a float valve and ballassembly for proper water level control.

)'. The overflow connection should include an elbow with an extension pipe that

drops below the water level in the tower sump. Gever block overflowconnections. Water should be allowed to flow freely without obstruction.

)+. The outlet connections for pump suction applications are provided with avortex breaker. Gote for gravity flow applications a vortex breaker is notre/uired or provided. A vent pipe or bleed valve should be installed at thehighest elbow of the piping system to prevent air locks and ensure free flow ofwater. Air locks can cause gravity flow restriction resulting in excessive wateraccumulation and eventual overflow of the cooling tower.

),. The outlet makeup and overflow connections are notched at the outer ridgeand should be held in position with the notch at )' o clock. This is to ensure

proper position of the vortex breaker float valve assembly and overflowextension which are internal and not visible from the exterior of the coolingtower.

)8. 0"C bulkhead connections must be held steady and in their factory-installedpositions when the connecting piping is being installed.

of composite FD0 material forming a rigid base for mounting the fan speedreducer drive shaft and motor.

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CONOMIC0/

When a pro%ect is originally designed the designer must decide whether a natural

draft or mechanical draft tower offers the best economic result. The designershould keep payback period in his mind and the life of the plant.6echanical draft towers are substantially less costly to purchase but have thedisadvantage of having a continuous auxiliary power draw. They are also physicallysmaller and shorter.

Gatural draft towers consume no auxiliary power but are very expensive topurchase and erect. They are very large and tall. 7ften times plants do not haveenough Jreal estateJ to fit such a large structure. 7ne must do an economic analysis to establish which option is the best choice

economically. They are also simplerN not having any moving parts and can /uickly install. They give their better result in geothermal power plant because the life andworking period of plant cannot be determined accurately. 0ayback period of forceddraft cooling tower is short but operation cost is high because it takes some power.7n the other hand payback period of natural draft cooling tower is more butoperation cost is less.

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Ot'er $(?$nt$ges o% %or*e( (r$%t *oolingtower $reEE

Cooling capacity can be controlled by controlling the amount of forced air. This can be installed at small area.

!igh performance can be achieved by increasing the air flow.

*t can be installed inside the building because they do not depend uponatmospheric air.

Iess water is waste because it is closed.

5rift loss is low.

*nstallation cost is less.

>fficiency will be increased.

*t is soundless device

APP ICATION0

A.C. 1 D>FD*L>DAT*7G C7I5 T7DAL> AG5 *C> 0IAGT

0IA T*C *G5= TD*>

0ower plants and other industries etc

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A/C Re%riger$tion/

The forced draft tower shown in the picture has the fan basin and piping locatedwithin the tower structure. *n this model the fan is located at the base. There areno louvered exterior walls. *nstead the structural steel or wood framing is coveredwith paneling made of aluminum galvani#ed steel or asbestos cement boards.

5uring operation the fan forces air at a low velocity hori#ontally through thepacking and then vertically against the downward flow of the water that occurs oneither side of the fan. The drift eliminators located at the top of the tower removewater entrained in the air. "ibration and noise are minimal since the rotatinge/uipment is built on a solid foundation. The fans handle mostly dry air greatlyreducing erosion and water condensation problems

Col( stor$ge

*ndustrial Cooling Tower that have found applications in *ce plant Cold storageall refrigeration system 5airy Chemical plant etc. made using latest techni/ues ofproducts our Water Cooling Towers are appreciated for their excellent

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performance and high precision. We are considered as one of the topmostWholesale Cooling Towers uppliers from *ndia.

Pl$sti* in(-stries/

*n the plastics industry a chilling system cools the hot plastic that is in%ected blownextruded or stamped. A chilling system can also cool down the e/uipment that is used tocreate plastic products $hydraulics of the molding machine gear box and barrel of theextruder that saves on energy and on the wear and tear of the machine itself.


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chlorofluorocarbon $!CFC& refrigerants there is a rapidly growing need to replace largecommercial air conditioning and refrigeration systems. To meet this demand we offer!"ACs air conditioning or modular chillers for large industrial and commercialapplications. 7ur systems are easy to replace or maintain and have a service life of )( to'( years giving you long term low cost energy efficiency.

MRI6agnetic resonance imaging $6D*& is a method of creating images of organs inside of thehuman body. *n the medical profession these devices are often used to distinguishpathological tissue i.e. a brain tumor from normal tissue. 6D* chillers are used to removethe heat from the 6D* scanner and transfer it to ether the surrounding ambient air or awater source such as a cooling tower.Ano(i@ingbecause anodi#ing process generates a lot of heat cooling is a must particularly for hardcoating processes. Chillers will do most of the work removing process heat using either anair or water cooled chiller. Air cooled units are generally installed outside and eliminatethe need for a tower. Water-cooled units are the most efficient method particularly inwarmer climates. They are installed inside a building with a cooling tower outside.

I*e ,l$nt/

*ndustrial cooling towers can be used to remove heat from various sources such asmachinery or heated process material. The primary use of large industrial coolingtowers is to remove the heat absorbed in the circulating cooling water systemsused in power plants petroleum refineries petrochemical plants natural gasprocessing plants food processing plants semi-conductor plants and otherindustrial facilities. The circulation rate of cooling water is usually high 1 re/uires asupply water make-up rate of around 8R.

Thermal provides with water treatment systems for cooling tower startup 1makeup. 7ver the last three decades Thorax has supplied these systems tohundreds of customers in *ndia.


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back to water the surplus $waste& heat which is removed from it needs to bedischarged by transfer to the air or to a body of water. This is a ma%orconsideration in sitting power plants and in the =[ sitting study in '((: fornuclear plants all recommendations were for sites within ' km of abundant water -

sea or estuary. This cooling function to condense the steam may be done in one of three ways9

Dire*t or Gon*e;t'ro-g'G cooling. *f the power plant is next to thesea a big river or large inland water body it may be done simply byrunning a large amount of water through the condensers in a single passand discharging it back into the sea lake or river a few degrees warmerand without much loss from the amount withdrawn. That is the simplestmethod. The water may be salt or fresh. ome small amount ofevaporation will occur off site due to the water being a few degreeswarmer.

Re*ir*-l$tion or in(ire*t *ooling/ *f the power plant does not haveaccess to abundant water cooling may be done by passing the steamthrough the condenser and then using a cooling tower where an updraught of air through water droplets cools the water. ometimes an on-site pond or canal may be sufficient for cooling the water. Gormally thecooling is chiefly through evaporation with simple heat transfer to the airbeing of less significance. The cooling tower evaporates up to 8R of theflow and the cooled water is then returned to the power plant?scondenser. The + to 8R or so is effectively consumed and must becontinually replaced. This is the main type of reticulating or indirectcooling.

Dr) *ooling/ A few power plants are cooled simply by air withoutrelying on the physics of evaporation. This may involve cooling towers witha closed circuit or high forced draft air flow through a finned assembly likea car radiator.

C&'C(USI&'

The problem which we have to face in natural draft cooling tower is that it takes alarge floor area to install it and it is also affected with surrounding and its

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cooling tower.doc