1.0
INTRODUCTION
Usually industrial processes produce large quantities of heat which must be permanently removed in order to maintain standard operating parameters. Cooling towers filled with packing are widely used to dissipate large heat loads from these processes, such as power generation units, chemical and petrochemical plants and refrigeration and air-conditioning systems, to the atmosphere. Their principle is based on heat and mass transfer using direct contact between ambient air and hot water through some types of packing. Indeed, the type of packing used in cooling tower has an important role in the tower as it controls the heat and mass transfer processes between water and air. Several researchers have investigated this subject through experimental analysis of the heat and mass transfer processes in these equipments
Cooled water is needed for, for example, air conditioners, manufacturing processes or power generation. A cooling tower is equipment used to reduce the temperature of a water stream by extracting heat from water and emitting it to the atmosphere. Cooling towers make use of evaporation whereby some of the water is evaporated into a moving air stream and subsequently discharged into the atmosphere. As a result, the remainder of the water is cooled down significantly. Cooling towers are able to lower the water temperatures more than devices that use only air to reject heat, like the radiator in a car, and are therefore more cost-effective and energy efficient.
2.0
OBJECTIVE
1.
To know the function of o f the cooling tower and the app lication in a building
2.
To know the essential important arts that install in the cooling tower system and its function
3.
Can see the operational and performance of the cooling tower system
4.
To compare the differences between air conditioning system and cooling tower
5.
To know the definition of each term in the cooling tower system such as water inlet, water outlet, and so on
1
3.0
LITERATURE REVIEW
Cooled water is needed for, for example, air conditioners, manufacturing processes or power Generation. A cooling tower is a heat removal system used to remove heat from a production or manufacturing process. The process can be a simple heating and air condition system in a building or a complex industrial process such the cooling of water used in the oil refinery process, a chemical plant or a power plant. A cooling tower will vary in size according to the needs of the process it cools for. Some cooling towers are found on the roof tops of high rise office buildings and others are as tall as an office building or even larger. Cooling towers allow the water to be cooled and then returned for use in the industrial or air conditioning process. This saves enormous amounts of o f money, time and energy. Common applications for cooling towers are providing cooled water for air-conditioning, manufacturing and electric power generation. The smallest cooling towers are designed to handle water streams of only a few gallons of water per minute supplied in small pipes like those might see in a residence, while the largest cool hundreds of thousands of gallons per minute supplied in pipes as much as
15
feet (about 5 meters) in diameter on a large power plant.
2
COOLING TOWER COMPONENTS
3.1
The basic components of a cooling tower include the frame and casing, fill, cold-water basin, drift eliminators, air inlet, louvers, nozzles and fans. T hese are described below: Frame and casing
Most towers have structural frames that support the exterior enclosures (casings), motors, fans, and other components. With some smaller designs, such as some glass fiber units, the casing may essentially be the frame. Fill
Most towers employ fills (made of plastic or wood) to facilitate heat transfer by maximizing water and air contact. There T here are two types of fill: y
Splash fill: water falls over successive layers of horizontal splash bars, continuously breaking into smaller droplets, while also wetting the fill surface. Plastic splash fills promote better heat transfer than wood woo d splash fills. fills.
y
Film
fill: consists of thin, closely spaced plastic surfaces over which the water spreads,
forming a thin film in contact with the air. These surfaces may be flat, corrugated, honeycombed, or other patterns. The film type of fill is the more efficient and provides same heat transfer in a smaller volume vo lume than the splash fill.Cold-water basin The cold-water basin is located at or near the bottom of the tower, and it receives the cooled water that flows down through the tower and fill. The basin usually has a sump or low point for the cold-water discharge connection. In many tower designs, the coldwater basin is beneath the entire fill. In some forced draft counter flow design, however, the water at the bottom of the fill is channeled to a perimeter trough that functions as the coldwater basin. Propeller fans are mounted beneath the fill to blow the air up through the tower. With this design, the tower is mounted on legs, providing easy access to the fans and their motors. Drift eliminat ors
These capture water droplets entrapped in the air stream that otherwise would be lost to the atmosphere. Air inlet
This is the point of entry for the air entering a tower. The inlet may take up an entire side of a tower (cross-flow design) or be located low on the side or the bottom of the tower (counter-flow design). 3
Louvers
Generally, cross-flow towers have inlet louvers. The purpose of louvers is to equalize air flow into the fill and retain the water within the tower. Many counter flow tower designs do not require louvers. Nozzles
These spray water to wet the fill. Uniform water distribution at the top of the fill is essential to achieve proper wetting of the entire fill surface. Nozzles can either be fixed and spray in a round or square patterns, or they can be part of a rotating assembly as found in some circular crosssection towers. Fans
Both axial (propeller type) and centrifugal fans are used in towers. Generally, propeller fans are used in induced draft towers and both propeller and centrifugal fans are found in forced draft towers. Depending upon their size, the type of propeller fans used is either fixed or variable pitch. A fan with non-automatic adjustable pitch blades can be used over a wide kW range because the fan can be adjusted to deliver the desired air flow at the lowest power consumption. Automatic variable pitch blades can vary air flow in response to changing load conditions.
4
3.2
COOLING TOWER OPERATION
There are two ways in which cooling towers work to remove heat---evaporation or the use of air. Temperature measurements taken during each of these cooling processes are called the wet-bulb air temperature and the dry-bulb air temperature. The dry-bulb air temperature is used when heat is removed by exposing the water to air. The wet-bulb temperature is used when heat is removed by the process of evaporation. Cooling towers are often seen in pairs or cells. Each of these cells is independent of each other and provides the possibility of backup if one should fail.
Water needing to be cooled is pumped to the top of the tower and then directed to flow down a designated path where the water forms into droplets. These droplets are met by a current of air that is blowing upward and past the water. The water is cooled by the air as it passes. It then collects at the bottom of the cooling tower structure where it is returned to the production process. Some air-cooled towers use large fans at the top of the structure to draw the air up.
Cooling through the evaporative process is taking advantage of a physical phenomenon. The evaporation of water (molecules in a liquid state change and become a gas, rising into the air) causes the water to automatically cool. The determining factor of how well this phenomenon works depends on the contrast of temperatures between the air and the water. The greater the difference, the better the cooling effect. Humid climates are not places in which to use this cooling process. The evaporative process transfers the heat from the water to the air and can be compared to the process and purpose of perspiration in the human body. A production process with lots of heated water to cool and located in a dry climate will cool well with an evaporative process. Evaporative processes are either open circuits or closed circuits. Some systems use both types
of
circuits
and
are
referred
to
as
two-stage
evaporative
cooling.
5
Evaporation system 1.
The ³hot´ water enters the top of the tower (note T5 in system diagram on front of unit) and isfed into troughs, from which it flows via notches onto the packing material in the tower (packings). The troughs at the top of the tower are designed designed to distribute the water uniformly over the packing packing with minimum splashing. splashing. There are several packings that can be used in the tower; you will probably be be using the flat, flat, slat-like material. material. The packings have an easily wetted surface and the water spreads over this to expose a large surface to the air stream.
2. The cooled water falls from the lowest packing into the collection basin, and exits the cooling tower (note (note T6 in in system system diagram). Next, the water is pumped to heaters. The two amber switches on the front of the unit operate the heaters, and note that this allows for three combinations combinations of heating load. load. In cooling tower applications the heating load results from a process requiring cooling, such as the condenser coils of an air conditioner. For
the Bench Top Cooling Tower, this is a simulated load, and comes in the form of the
³load tank´. 3. Due to evaporation from the water, an accumulator or ³make-up tank´ must maintain the quantity of water in the cooling system. system. The volume of water added to the system can be measured by the lost of water in the make-up tank.
6
4. Droplets of water (resulting from splashing, etc) may become entrained in the air stream and then lost lost from the system. system. This loss does not contribute contribute to the cooling, but must replenish by the accumulator or make-up tank. To minimize this loss, a droplet droplet arrester, or eliminator is fitted fitted at the tower outlet. outlet. This component causes droplets to coalesce, forming drops which are too large to be entrained and these will fall back into the packings. 5. Water flow is controlled by the control valve on the float-type flow meter (rotameter) at the far right of the untit. untit. Note that a turbine flow flow meter has been installed (retrofitted) to the unit to measure the flow rate using the data acquisition system. Air System: 1.
Using a small centrifugal fan with damper to control flow rate, air is driven up through the wet packings. packings.
Air enters the bottom of the tower and flows flows past a dry bulb
temperature sensor (T1) and a wet-bulb temperature sensor (T2). (T2). At the exit of the cooling (at the top) the exit air dry bulb temperature (T3) and wet-bulb temperature (T4) are measured. Note that the wicks wicks on the wet bulb sensor are immersed immersed in reservoirs of water that may may require filling. filling.
It should should be observed observed that the change change of dry bulb
temperature is smaller smaller than the change of wet bulb temperatures. This indicates that the air leaving is almost saturated, ie, Relative Humidity approaches 100%. This increase in the moisture content of the air is due to the conversion of water into steam and the latent heat for this will account for most of o f the cooling effect. 2. If the cooling load was switched off and the unit allowed stabilizing, it should be found that the water will leave the basin close to the wet bulb temperature of the air entering. According to the local atmospheric conditions, this can be several degrees below the incoming air (dry bulb) temperature. 3. Without a simulated load, the cooling tower would be able to cool the water to a temperature that approaches the wet bulb temperature. This is an ³ideal´ parameter of this system.
7
3.3
DIFFERENCES BETWEEN AIR CONDITIONING AND COOLING TOWER
There are several differences between air a ir conditioning and cooling tower, which is:
Cooling tower
Air-conditioning unit
The cooling tower is where heat is exchanged
At the condenser where the heat is exchanged.
It's usually located outside: rooftop
Located inside and outside rooms.
Supersized for whole floor/building, use for large area: shopping mall, library. Uses water to transfer heat due to water`s ability of heat conductivity
Usually for small area: rooms, roo ms, houses.
Use refrigerant to transfer heat
Hot air in room refrigerant in AHU water Hot air in room evaporator compressor in heat exchanger cooling tower (dissipates the heat to surrounding) surrounding) = repeats. repeat s.
3.4
condenser
(heat
blow
off
to
surroundings) expansion valve.= repeats.
TERM USED IN COOLING TOWER
ACFM: The actual volumetric flow rate of air-vapor mixture, cubic feet of air moved per
minute.. Unit: cu ft per min. Air Horsepower: The power output developed by a fan in moving a given air rate against a
given resistance. Unit: hp. Symbol: ahp. Air lnlet: Opening in a cooling tower through which air enters. Sometimes referred to as the
louvered face on induced draft towers. Air R ate ate: Mass flow of dry air per square foot of cross - sectional area in the tower's heat
transfer region per hour. Unit: lb per sq ft per hr. Symbol: G'.(See Total Air Rate). Air Travel: Distance which air travels in its passage through the fill. Measured vertically on
counterflow towers and horizontally on crossfl cro ssflow ow towers. to wers. Unit: ft. Air Velocity: Velocity of air-vapor mixture through a specific region of the tower (i.e. the fan).
Unit: ft per min. Symbol: V. Ambient Wet-Bulb Temperature: The wet-bulb temperature of the air encompassing a cooling
tower not including any te mperature contribution by the tower itself. itself. Generally measured upwind 8
of a tower in a number of locations sufficient to account for all extraneous sources of heat. Unit: øF. Symbol: AWB. Approach: Difference between the cold water temperature and either the ambient or entering
wet-bulb temperature. (CW-EWB=A) Unit: øF. Atmospheric: Refers to the movement of air through a cooling tower purely by natural means,
or by the aspirating effect of o f water flow. Automatic Variable-Pitch Fan: A propeller type fan whose hub incorporates a mechanism
which enables the fan blades to be re-pitched simultaneously and automatically. They are used on cooling towers and air-cooled heat exchangers to trim capacity a nd/or conserve energy. Basin: See "Collection Basin" and "Distribution Basin". Basin Curb: Top level of the cold water basin retaining wall; usually the datum from which
pumping head and various elevations of the tower are measured. Bay: The area between adjacent transverse t ransverse and longitudinal framing bents. Bent: A transverse or longitudinal line o f structural framework composed of o f columns, girts, ties,
and diagonal bracing members. Bleed-Off : See "Blowdown". Blowdown: Water discharged from the system to control concentrations of salts or other
impurities in the circulating water. Units % of circulating water rate or gpm. Blower: A squirrel-cage (centrifugal) type fan; usually applied for operation at higher-than-
normal static pressures. Blowout - See "Windage". BTU (British Thermal Unit): The amount of heat gain (or loss) required to raise (or lower) the
temperature of one pound of water one degree (1ø)F. Capacity: The amount of water (gpm) that a cooling tower will cool through a specified range,
at a specified approach and wet-bulb temperature. Unit: gpm. Casing: Exterior enclosing wall of a tower exclusive of the louvers. Cell: Smallest tower subdivision which can function as an independent unit with regard to air
and water flow; it is bounded by either exterior walls or partition walls. Each cell may have one or more fans and one o r more distribution systems. CFM: The volumetric flow rate of air-vapor mixture, cubic feet of air moved per minute. Unit:
cu ft per min. 9
Chimney: See "Shell".
enter ing the cooling tower. Unit: gpm. Circulating Water R ate ate - Quantity of hot water entering Cold Water Temperat ure: Temperature of the water leaving the collection basin, exclusive of
any temperature effects incurred by the addition of make-up and/or the removal of blowdown. Unit: øF. Symbol: CW. Collection Basin: Vessel below and integral with the tower where water is transiently collected
and directed to the t he sump or pump suction line. flow direction d irection through the fill is countercurrent to that of the falling water. Counterflow: Air flow Crossflow: Air flow direction through the fill is essentially perpendicular to that of the falling
water. Distribution Basin: Shallow pan-type elevated basin used to distribute hot water over the tower
fill by means of orifices in the basin floor. Application is normally limited limited to crossflow crossflow towers. Distribution System: Those parts of a tower beginning with the inlet connection which
distribute the hot circulating water within the tower to the points where it contacts the air for effective cooling. May include headers, laterals branch arms, nozzles, distribution basins, and flow-regulating devices. Double-Flow: A crossflow cooling tower where two opposed fill banks are served by a common
air plenum. Drift: Circulating water lost from the tower as liquid droplets entrained in the exhaust air stream.
Units:
%
of circulating water rate or gpm. (For more precise work, an L/G parameter is used, and
drift becomes pounds of water per million million pounds po unds of exhaust air. Unit: ppm.) Drift Eliminators: An assembly of baffles or labyrinth passages through which the air passes
prior to its exit from the tower, for the purpose of removing entrained water droplets from the exhaust air. Driver: Primary drive for the fan drive assembly. Although electric motors predominate, it may
also be a gas engine, steam turbine, hydraulic motor or other power source. Dry-Bulb T emperat ure: The temperature of the entering or ambient air adjacent to the cooling
tower as measured with a dry-bulb thermometer. Unit: Unit: øF. Symbol: S ymbol: DB. Entering Wet-Bulb Temperat ure: The wet-bulb temperature of the air actually entering the
tower, including any effects of recirculation. In testing, the average of multiple readings taken at the air inlets to establish a true entering wet-bulb te mperature. Unit øF. Symbol: EWB. 10
Evaluation: A determination of the total cost of owning a cooling tower for a specific period of
time. Includes first cost of tower and attendant devices, cost of operation, cost of maintenance and/or repair, cost of land use, co st of financing, etc., all normalized to a specific point in time. Evaporation Loss: Water evaporated from the circulating water into the air stream in the
cooling process. Units: % of circulating water rate or o r gpm. Exhaust (Exit) Wet-Bulb Temperature: See "Leaving Wet-Bulb Temperature".
Fan Cylinder: Cylindrical or venturi-shaped structure in which a propeller fan operates.
Sometimes referred to as a fan "stack" on larger towers. Fan Deck : Surface enclosing the top structure of an induced draft cooling tower, exclusive of the
distribution basins on a crossflow tower. Fan Pitch: The angle which the blades of a propeller fan make with the plane of rotation,
measured at a prescribed point on each blade. Unit: degrees. Fan Scroll: Convolute housing in which a centrifugal (blower) fan operates. Fill: That portion of a cooling tower which constitutes its primary heat transfer surface.
Sometimes referred to as "packing". Fill Cube: (1) Counterflow: The amount of fill required in a volume one bay long by one bay
wide by an air a ir travel high. Unit: cu ft. (2) Crossflow: Crossflow: The T he amount of fill required in a vo lume one bay long by an air travel wide by one story sto ry high. Unit: cu ft. Fill Deck : One of a succession of horizontal layers of splash bars utilized in a splash-filled
cooling tower. The number of fill decks constituting overall fill height, as well as the number of splash bars incorporated within each fill deck, establishes the effective primary heat transfer surface. Fill Sheet: One of a succession of vertically-arranged, closely-spaced panels over which flowing
water spreads to offer maximum surface exposure to the air in a film-filled cooling tower. Sheets may be flat, requiring spacers for consistent separation; or they may be formed into corrugated, chevron, and other patterns whose protrusions provide proper spacing, and whose convolutions provide increased heat-transfer capability. Film-Filled : Descriptive of a cooling tower in which film-type fill is utilized for the primary
heat-transfer surface. Float Valve: A valve which is mechanically actuated by a float. Utilized on many cooling
towers to control make-up water supply. supp ly. 11
Flow-Control Valves: Manually controlled valves which are used to balance flow of incoming
water to all sections of the tower. to wer. Flume: A trough which may be either totally enclosed, or open at the top. Flumes are sometimes
used in cooling towers for primary supply of water to various sections of the distribution system. Fogging: A reference to the visibility and path of the effluent air stream after having exited the
cooling tower. If visible and close to the ground it is referred to as "fog". If elevated it is normally called the "plume". Forced Draft: Refers to the movement of air under pressure through a cooling tower. Fans of
forced draft towers are located at the t he air inlets to "force" air through the tower. to wer. Geareducer: See "Speed Reducer". (Geareducer is a Trademark of the Marley Cooling Tower
Co.) Heat Load: Total heat to be removed from the circulating water by the cooling tower per unit
time. Units: Btu per min. or Btu per hr. Height: On cooling towers erected over a concrete basin, height is measured from the elevation
of the basin curb. "Nominal" heights are usually measured to the fan deck elevation, not including the height of the fan cylinder. Heights for towers on which a wood, steel, or plastic basin, is included within the manufacturer's scope of supply are generally measured from the lowermost point of the basin, and are usually overall of the tower. Unit: ft. Horsepower: The power output of a motor, turbine, or engine (also see Brake Horsepower).
Unit: hp. Symbol: hp. Hot Water Temperat ure: Temperature of circulating water entering the cooling tower's
distribution system. Unit: F. Symbol: HW. Hydrogen Ion Concentrati on - See "pH".
lnduced Draft: Refers to the movement of air through a cooling tower by means of an induced
partial vacuum.
Fans
of induced draft towers are located at the air discharges to "draw" air
through the tower. Inlet Wet-Bulb Temperature: See "Entering Wet-Bulb Temperature". Interference - The thermal contamination of a tower's inlet air by an external heat source. (i.e.
the discharge plume of another cooling tower.) Leaving Wet-Bulb Temperature: Wet-bulb temperature of the air discharged from a cooling
tower. Unit: F. Symbol: LWB. 12
Length: For crossflow towers, length is always perpendicular to the direction of air flow through
the fill (air travel), or from casing to casing. For counterflow towers, length is always parallel to the long dimension of a multi-cell tower, and parallel to the intended direction of cellular extension on single-cell towers. Unit: ft. Liquid-to-Gas R ati atio: A ratio of the total mass flows of water and dry air in a cooling tower.
(See Total Air Rate & Total Water Rate) Unit: lb per lb. Symbol: L/G. Longitudinal: Pertaining to occurrances in the direction of to wer length. Louvers: Blade or passage type assemblies installed at the air inlet face of a cooling tower to
control water splashout and/or promote uniform air flow through the fill. In the case of film-type crossflow crossflow fill, they t hey may be integrally molded to t he fill sheets. Mak ee-Up: Water added to the circulating water system to replace water lost by evaporation,
drift, windage, blowdown, and leakage. Units: % of circulating water rate or gpm. Mechanical Draft: Refers to the movement of air through a cooling tower by means of a fan or
other mechanical device. Module: A preassembled portion or section of a cooling tower cell. On larger factory-assembled
towers two or more shipped modules may requ ire joining to make a cell. ce ll. Natural Draft: Refers to the movement of air through a cooling tower purely by natural means.
Typically, by the driving force of a density differential. Net Effective Volu me: That portion of the total structural volume within which the circulating
water is in intimate contact with the flowing air. Unit: cu ft. Nozzle: A device used for controlled distribution of water in a cooling tower. Nozzles are
designed to deliver water in a spray spra y pattern either by pressure or by gravity flow. Pack ing ing: See "Fill". Partition: An interior wall subdividing the tower into cells or into separate fan plenum
chambers. Partitions may also be selectively installed to r educe windage water loss. Perf ormance: See "Capacity".
pH: A scale for expressing acidity or alkalinity of the circulating or make-up water. A pH below
7.0 indicates acidity acidity and above 7.0 indicates alkalinity. alkalinity. A pH of 7.0 indicates neutral water. Pitot Tube: An instrument that operates on the principle of d ifferential pressures. Its primary use
on a cooling to wer is in the measurement of circulating water flow. 13
Plenum Chamber: The enclosed space between the drift eliminators and the fan in induced draft
towers, or the enclosed space between the fan and the fill in forced draft towers. Plume: The effluent mixture of heated air and water vapor (usually visible) discharged from a
cooling tower. Psychrometer: An instrument incorporating both a dry-bulb and a wet-bulb thermometer, by
which simultaneous dry-bulb and wet-bulb temperature te mperature readings can be taken. Pump Head: See "Tower Pumping Head". R ange ange: Difference between the hot water temperature and t he cold water temperature (HW - CW
= R) Unit: F. R ecirculation: Describes a condition in which a portion of the tower's discharge air re-enters the
air inlets along with the fresh air. Its effect is an elevation of the average entering wet-bulb temperature compared to the ambient. R iser iser: Piping which connects the circulating water supply line, from the level of the base of the
tower or the supply header, to the tower's distribution system. Shell - The chimney-like structure, usually hyperbolic in cross-section, utilized to induce air flow through a natural draft tower. Sometimes referred to as a "stack" or "veil". Speed R ed educer: A mechanical device incorporated between the driver and the fan of a
mechanical draft tower, designed to reduce the speed of the driver to an optimum speed for the fan. The use of geared reduction units predominates in the cooling tower industry, although smaller towers will utilize differential pulleys and V-belts for the transmission of relatively low power. (Geareducer is a Trademark of the Marley Cooling Tower Co.) Splash B ar: One of a succession of equally-spaced horizontal bars comprising the splash surface
of a fill deck in a splash-filled cooling tower. Splash bars may be flat, or may be formed into a shaped cross-section for improved structural rigidity and/or improved heat transfer capability. When flat, they are sometimes referred to as "slats" or "lath". Splash-Filled: Descriptive of a cooling tower in which splash-type fill is used for the primary
heat transfer surface. Spray-Filled : Descriptive of a cooling tower which has no fill, with water-to-air contact
depending entirely upon the t he water break-up and pattern patt ern afforded by pressure spray nozzles. Stack : An extended fan cylinder whose primary purpose is to achieve elevation of the discharge
plume. Also see "Fan Cylinder" and "Shell". 14
Stack Effect: Descriptive of the capability of a tower shell or extended fan cylinder to induce air
(or aid in its induction) through a cooling tower. Standard Air: Air having a density of 0.075 lb per cu ft. Essentially equivalent to 70 øF dry air
at 29.92 in Hg barometric pressure. Story: The vertical dimension between successive levels of horizontal framework ties, girts,
joists, or beams. Story dimensions vary depending upon the size and strength characteristics of the framework material used. Unit: ft. Sump: A depressed chamber either below or alongside (but contiguous to) the collection basin,
into which the water flows to facilitate pump suction. Sumps may also be designed as collection points for silt and sludge to aid in clea ning. Total Air R ate ate: Total mass flow of dry air per hour through the tower. Unit: lb per hr. Symbol:
G. Total Water R ate ate: Total mass flow of water per hour through the tower. Unit: lb per hr.
Symbol: L. Tower Pumping Head: The static lift from the elevation of the basin curb to the centerline
elevation of the distribution system inlet plus the total pressure (converted to ft of water) necessary at that point to effect proper distribution of the water to its point of contact with the air. Unit: ft of water. d irection of tower width. Transverse: Pertaining to occurrences in the direction Velocity R ecovery Fan Cylinder - A fan cylinder on which the discharge portion is extended in
height and outwardly flared. Its effect is to decrease the total head differential across the fan, resulting in either an increase in air rate at constant horsepower, or a decrease in horsepower at constant air rate. Water Inlet ± Where the water wat er insert the cooling tower Water Outlet ± Where the water out from the packed column. Water Loading: Circulating water rate per horizontal square foot of fill plan area of the cooling
tower. Unit: gpm per sq ft. Water R ate ate: Mass flow of water per square foot of fill plan area of the cooling tower per hour.
Unit: lb per sq ft per hr. Symbol: L. Wet-Bulb Temperature: The temperature of the entering or ambient air adjacent to the cooling
tower as measured with a wet-bulb thermometer. Unit: F. Symbol: WB. 15
Wet-Bulb Thermometer: A thermometer whose bulb is encased within a wet ted wick. Windage : Water lost from the tower because of the effects of wind. Sometimes called
"blowout". Wind Load: The load imposed upon a structure by a wind blowing against its surface. Unit:
lb/sq ft.
16
3.0
PROBLEMS RELATED
Cooling Water Temperat ure Increase PROBLEMS
Excessive or inadequate cooling water flow
SOLUTION
Adjust to the specified flow
Irregular flow of air
Improve ventilation
Re-circulation of air from tower outlet
Improve ventilation
Clogging of holes in Upper Water Basin
Remove dirt and scale
Improper flow flow of air from fan
Adjust the angle of fan blades
Damaged fill
Replace honeycomb fills
Cooling Water Volume Decrease PROBLEMS
Blocking of the sprinkler holes in Upper Water Basin Blocking of strainer mesh
SOLUTION
Remove dirt and scale Remove strainer
Water level decrease in the Lower Water Basin Adjust float float valve Improper selection of water circulating pump
Replace the pump with proper capacity
17
Noise and Vibration PROBLEMS
SOLUTION
Fan
Adjust the fan mounting
blade tips touching casing
Bending of fan shaft
Adjust bend at special shop
Loose bolts
Tighten loose bots
Motor damage
Replace motor
Damage in fan
Replace fan
Water Carry Over PROBLEMS
SOLUTION
Excessive circulating of water
Adjust the water flow flow with valve
Excessive air flow flow
Adjust fan blade angles
Excessive Current Flow PROBLEMS
Drop in voltage
SOLUTION
Check
supply
voltage
and
contact
company.
Irregularities in the angles
Make careful adjustment
Overload through excessive air flow flow
Adjust fan blade angles
18
5.0
CONCLUSION AND RECOMMENDATIONS From
the lab that we have done, we know that cooling tower and air conditioning units
work the same way. Instead of cooling just the small, insulated space inside a room or houses, a cooling tower cools a large area, whole buildings, a shopping complex or an entire business. Cooling tower use water as it main medium to transfer heat to surroundings while air conditioners use chemicals that easily convert from a gas to a liquid and back again. This chemical is used to transfer heat from from the air inside of a home to the outside outside air. We also have known each of the components that exist in an air cooling tower. Roughly cooling tower has no differences with air conditioning units except the sizes and the medium for heat transfer that use water rather than refrigerant in air conditioning unit s. In cooling tower, the condensed water wat er been transferred to condenser and through to expansion valve and continuing to evaporator. After that air handling units controlled the amount of cool temperature that entered and to be distributed. After the AHU, the fresh and cool temperature gets to the consumer and the heat are sucked by AHU and the processes pro cesses are repeated continuously.
19
5.1
For
RECOMMENDATION
recommendations, it is recommend that:
Choose the right capacity
For
a cooling tower it is obvious that it only suitable to cover large area such as shopping
complex, high raise offices, library and ot hers. While for air conditioning unit, it suitable for small users such as houses, rooms and others. It is because its capacity is smaller than coolin coo ling g tower .and
Install at suitable area
Cooling tower is large and usually been installed at roof top for heat dissimilation. While air conditioning units usually installed outside rooms or houses.
Minimize uses
Always turn off the units when it is not been used and use wisely according to surrounding and human capacity. As rainy seasons, minimize the power or when there are not many people in a building, adjust the temperature controller according the capac ity.
Design green building
In the future it is hopefully that there are more architect and engineer design green buildings that use more natural ventilation as it reduce the use of cooling tower and airconditioning unit as we know that this two are one of the reasons the increases of our earth temperature as the dissipate heat to surrounding. The larger cooling tower, the more heat that it release to environment.
20
6.0
REFERENCES
Bureau of Energy Efficiency, Ministry of Power, India. Cooling Towers. In: Energy Efficiency in Electrical Utilities. Chapter 7, pg 135 - 151. 2004
Australian Institute of Air Conditioning Refrigeration and Heating (AIRAH). Types of Cooling Towers. In: Selecting a Cooling Tower Level 1 ± Participant Guide Version 1.0
www.airah.org.au/downloads/CPD-samplepg.pdf.
http://www.ehow.com/how-does_4899957_cooling-tower-work.html
www.wea-inc.com/cooling-tower-calculators.htm
www.coolingtowerpricebook.com
www.en.wikipedia.org/wiki/Cooling_tower
www.cti.org/whatis/coolingtowerdetail.shtm
www.superpages.com.my/industrial/cooling-towers
http://www.perfectcoolingtowers.com/troubleshoot.html
W.M. Simpson, T.K. Sherwood, Performance of small mechanical draft cooling towers, American Society of Refrigerating Engineering 52 (1946) 535±543, and 574±576
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7.0
APPENDICES
Figure 1:
from side, cooling tower
Figure
3: Cooling Tower
Figure
2: from above, cooling tower fan
Figure
4: cooling tower
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