chế biến khí cooling towers

SECTION 11 Cooling Towers INTRODUCTION COOLING TOWER PSYCHROMETRICS The purpose of this section is to provide a basic understanding of the design and operation of a cooling tower A cooling tower allows water to be cooled by ambient air through evaporation Psychrometry is the study of cooling by evaporation Maximum evaporation takes place when water, in the form of tiny droplets, is exposed to the maximum air flow for the longest possible time The process of evaporation through removal of latent FIG 11-1 Nomenclature kgs kgw L L/G Q PF R V va vas vs Acfm = actual volumetric flow rate of air-vapor mixture, m3/h ahp = air power, kW AWB = ambient wet bulb temperature, °C B = combined water loss through blowdown and windage, % of circulating water or m3/h CWT = cold water temperature, °C DB = dry bulb temperature, °C E = water evaporated, % of circulating water or m3/h G = air rate, kg/(m2 • h) = specific enthalpy of dry air, kJ/kg has = hs – ha, kJ/kg hs = enthalpy of moist air at saturation per kg of dry air, kJ/kg HWT = hot water temperature, °C kilograms of dry air kilograms of water water rate, kg/(m2 • h) liquid to gas ratio, kg/kg m3/h performance factor, dimensionless cooling tower range, °C air velocity, m/h specific volume of dry air, m3/kg vs – va, m3/kg volume of moist air at saturation per kg of dry air, m3/kg Ws = kgw/kgaa, humidity ratio at saturation WB = wet bulb temperature, °C DEFINITIONS OF WORDS AND PHRASES USED IN COOLING TOWERS = = = = = = = = = = = Capacity: The amount of water that a cooling tower will cool through a specified range, at a specified approach and wetbulb temperature Air inlet: Opening in a cooling tower through which air enters Sometimes referred to as the louvered face on induced draft towers 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 or more distribution systems Air power: The power output developed by a fan in moving a given air rate against a given resistance Circulation rate: Actual water flow rate through a given tower Air rate: Mass flow of dry air per square foot of cross-sectional area in the tower’s heat transfer region per hour Cold water temperature: Temperature of the water leaving the collection basin, exclusive of any temperature effects incurred by the addition of makeup and/or the removal of blowdown Air velocity: Velocity of air-vapor mixture through a specific region of the tower (i.e the fan) Ambient wet-bulb temperature: The wet-bulb temperature of the air encompassing a cooling tower, not including any temperature contribution by the tower itself Generally measured upwind of a tower, in a number of locations sufficient to account for all extraneous sources of heat Collection basin: Chamber below and integral with the tower where water is transiently collected and directed to the sump or pump suction line Counterflow: Air flow direction through the fill is countercurrent to that of the falling water Approach: Difference between the cold water temperature and the entering wet-bulb temperature Crossflow: Air flow direction through the fill is essentially perpendicular to that of the falling water Blowdown: Water discharged from the system to control concentrations of salt or other impurities in the circulating 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 to crossflow towers 11-1 Double-flow: A crossflow cooling tower where two opposed fill banks are served by a common air plenum Drift: Circulating water loss from the tower as liquid droplets entrained in the exhaust air stream Units percent of circulating water rate or gpm [For more precise work, an L/G parameter is used, and drift becomes kilograms of water per million kilograms of exhaust air (ppmw).] 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 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 filmtype crossflow fill, they may be integrally molded to the fill sheets Makeup: Water added to the circulating water system to replace water lost by evaporation, drift, windage, blowdown, and leakage 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 Dry-bulb temperature: The temperature of the entering or ambient air adjacent to the cooling tower as measured with a dry-bulb thermometer Net effect volume: That portion of the total structural volume within which the circulating water is in intimate contact with the flowing air Evaporation loss: Water evaporated from the circulating water into the air stream in the cooling process Performance factor: Variable used in determining performance characteristics in cooling towers Fan cylinder: Cylindrical or venturi-shaped structure in which a propeller fan operates Sometimes referred to as a fan “stack” on larger towers Psychrometer: An instrument incorporating both a dry-bulb and a wet-bulb thermometer, by which simultaneous drybulb and wet-bulb temperature readings can be taken Fan deck: Surface enclosing the top of an induced draft cooling tower, exclusive of the distribution basins on a crossflow tower Range: Difference between the hot water temperature and the cold water temperature 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 Fill: That portion of a cooling tower which constitutes its primary heat transfer surface Sometimes referred to as “packing.” Forced draft: Refers to the movement of air under pressure through a cooling tower Fans of forced draft towers are located at the air inlets to “force” air through the tower Hot water temperature: Temperature of circulating water entering the cooling tower’s distribution system Induced 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 Recirculation: 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 temperatures compared to the ambient Water rate: Mass flow of water per square foot of fill plan area of the cooling tower per hour Wet-bulb temperature: the temperature of the entering or ambient air adjacent to the cooling tower as measured with a wet-bulb thermometer Wet-Bulb thermometer: A thermometer whose bulb is encased within a wetted wick Windage: Water lost from the tower because of the effects of wind Wind load: The load imposed upon a structure by a wind blowing against its surface Liquid-to-gas ratio: A ratio of the total mass flows of water and dry air in a cooling tower (See Air Rate and Water Rate) heat allows the water to be cooled below the ambient dry-bulb temperature The dry air enters the cooling tower and begins to gain moisture and enthalpy in an effort to reach equilibrium with the water The water may be cooled 8°C or more while the air mass dry-bulb temperature may increase only slightly A psychrometric chart (Fig 11-2) may be used to illustrate the relationships between wet- and dry-bulb temperatures All nomenclature is indicated in Fig 11-1 tower Water cannot be cooled below the wet-bulb temperature by evaporation The air entering the tower at a temperature of 24°C and 100% relative humidity has a 24°C “wet-bulb” temperature The wet-bulb temperature is usually measured using a sling psychrometer Wet bulb and dry bulb data for various locations around the world are shown in Figs 11-3a and 11-3b Wet-bulb Temperature Cooling water is circulated through equipment to absorb and carry away heat The basic cooling systems are shown in Fig 11-4 The open recirculating system is the most common for industrial plants The basis for thermal design of an evaporative type cooling tower is the wet-bulb temperature of the air entering the Types of Cooling Systems 11-2 FIG 11-2 Psychrometric Chart 11-3 FIG 11-3a Dry Bulb/Wet Bulb Temperature Data2 U.S State and Stations ALABAMA    Alexander City    Anniston    Auburn    Birmingham    Decatur    Dothan    Florence    Gadsden    Huntsville    Mobile AP    Mobile CO    Montgomery    Selma-Craig    Talladega    Tuscaloosa ALASKA    Anchorage    Barrow    Fairbanks    Juneau    Kodiak    Nome ARIZONA    Douglas    Flagstaff    Fort Huachuca    Kingman    Nogales    Phoenix    Prescott    Tucson    Winslow    Yuma ARKANSAS    Blytheville    Camden    El Dorado    Fayetteville    Fort Smith    Hot Springs    Jonesboro    Little Rock    Pine Bluff    Texarkana CALIFORNIA    Bakersfield    Barstow    Blythe    Burbank    Chico    Concord    Covina    Crescent City    Downey    El Cajon    El Centro    Escondido    Eureka/Arcata    Fairfield-Travis AFB    Fresno    Hamilton    Laguna Beach    Livermore    Lompoc,     Vandenburg AFB    Long Beach    Los Angeles AP    Los Angeles CO    Merced-Castle AFB    Modesto    Monterey    Napa    Needles    Oakland    Oceanside    Ontario    Oxnard    Palmdale    Palm Springs    Pasadena Design Design Dry-Bulb Wet-Bulb °C 5% °C 5% 33 33 33 33 33 33 33 33 33 33 33 34 34 33 34 26 26 26 24 24 26 24 24 24 26 26 26 26 26 25 19    24 19 17 15 14    16 14 13 13 34 27 32 36 34 41 33 38 34 42 20 15 19 21 21 24 18 22 18 25 33 34 34 33 35 34 33 34 35 34 26 26 26 24 26 26 26 26 27 26 37 39 42 31 37 34 33 17 30 26 42 28 17 33 36 27 25 34 21 21 23 21 20 20 21 15 21 20 26 21 15 19 21 19 20 20 19 25 25 30 36 35 20 33 42 24 25 36 25 37 42 33 16 20 20 21 21 21 16 20 23 17 20 22 19 19 23 21 Design Design Dry-Bulb Wet-Bulb °C 5% °C 5%    Petaluma 31 20    Pomona 35 22    Redding 38 20    Redlands 36 22    Richmond 24 17    Riverside-March AFB 35 21    Sacramento 34 21    Salinas 19 15    San Bernardino,     Norton AFB 36 22    San Diego 26 20    San Fernando 31 21    San Francisco AP 23 17    San Francisco CO 21 16    San Jose 25 18    San Luis Obispo 29 21    Santa Ana 28 21    Santa Barbara 24 19    Santa Cruz 20 16    Santa Maria 23 17    Santa Monica 25 20    Santa Paula 29 20    Santa Rosa 33 19    Stockton 34 20    Ukiah 33 19    Visalia 36 21    Yreka 32 18    Yuba City 37 20 COLORADO    Alamosa 27 16    Boulder 32 17    Colorado Springs 30 16    Denver 32 17    Durango 29 17    Fort Collins 32 17    Grand Junction 33 17    Greeley 33 17    La Junta 35 21    Leadville 26 12    Pueblo 33 18    Sterling 32 18    Trinidad 32 18 CONNECTICUT    Bridgeport 27 23    Hartford,     Brainard Field 29 23    New Haven 28 23    New London 28 23    Norwalk 27 23    Norwich 28 23    Waterbury 28 22    Windsor Locks,     Bradley Field 29 23 DELAWARE    Dover AFB 31 24    Wilmington 31 24 DISTRICT OF COLUMBIA    Andrews AFB 31 24    Washington National 32 24 FLORIDA    Belle Glade 32 26    Cape Kennedy 31 26    Daytona Beach 31 26    Fort Lauderdale 32 26    Fort Myers 33 26    Fort Pierce 32 26    Gainesville 33 26    Jacksonville 33 26    Key West 32 26    Lakeland 32 26    Miami 32 26    Miami Beach 31 26    Ocala 33 26    Orlando 33 26    Panama City,     Tyndall AFB 32 26    Pensacola 33 26    St Augustine 31 26    St Petersburg 32 26    Sanford 33 26 U.S State and Stations U.S State and Stations    Sarasota    Tallahassee    Tampa    West Palm Beach GEORGIA    Albany,     Turner AFB    Americus    Athens    Atlanta    Augusta    Brunswick    Columbus,     Lawson AFB    Dalton    Dublin    Gainesville    Griffin    La Grange    Macon    Marietta,     Dobbins AFB    Moultrie    Rome    Savannah-Travis    Valdosta-Moody AFB    Waycross HAWAII    Hilo    Honolulu    Kaneohe Bay    Wahiawa IDAHO    Boise    Burley    Coeur d’Alene    Idaho Falls    Lewiston    Moscow    Mountain Home AFB    Pocatello    Twin Falls ILLINOIS    Aurora    Belleville, Scott AFB    Bloomington    Carbondale    Champaign/Urbana    Chicago, Midway    Chicago, O’Hare    Chicago    Danville    Decatur    Dixon    Elgin    Freeport    Galesburg    Greenville    Joliet    Kankakee    La Salle/Peru    Macomb    Moline    Mt Vernon    Peoria    Quincy    Rantoul,     Chanute AFB    Rockford    Springfield    Waukegan INDIANA    Anderson    Bedford    Bloomington    Columbus,     Bakalar AFB    Crawfordsville    Evansville    Fort Wayne    Goshen 11-4 Design Design Dry-Bulb Wet-Bulb °C 5% °C 5% 32 26 32 26 32 26 32 26 34 33 32 32 34 31 26 25 24 24 26 26 33 33 33 32 31 32 33 25 25 25 24 24 24 25 32 33 33 33 33 33 24 26 25 26 26 26 28 29 28 29 23 23 24 23 33 33 28 29 32 29 34 32 33 18 16 16 16 18 17 17 16 16 31 32 31 32 32 31 30 31 31 31 31 30 31 31 32 31 31 31 32 31 32 31 32 24 24 24 25 24 23 23 24 24 24 24 24 23 24 24 24 24 24 24 24 24 24 25 32 31 32 31 24 23 24 24 32 32 32 24 24 24 32 31 33 31 30 24 24 25 23 23 U.S State and Stations    Hobart    Huntington    Indianapolis    Jeffersonville    Kokomo    Lafayette    La Porte    Marion    Muncie    Peru,     Bunker Hill AFB    Richmond    Shelbyville    South Bend    Terre Haute    Valparaiso    Vincennes IOWA    Ames    Burlington    Cedar Rapids    Clinton    Council Bluffs    Des Moines    Dubuque    Fort Dodge    Iowa City    Keokuk    Marshalltown    Mason City    Newton    Ottumwa    Sioux City    Waterloo KANSAS    Atchison    Chanute    Dodge City    El Dorado    Emporia    Garden City    Goodland    Great Bend    Hutchinson    Liberal    Manhattan,     Fort Riley    Parsons    Russell    Salina    Topeka    Wichita KENTUCKY    Ashland    Bowling Green    Corbin    Covington    Hopkinsville,     Campbell AFB    Lexington    Louisville    Madisonville    Owensboro    Paducah LOUISIANA    Alexandria    Baton Rouge    Bogalusa    Houma    Lafayette    Lake Charles    Minden    Monroe    Natchitoches    New Orleans    Shreveport MAINE    Augusta    Bangor, Dow AFB    Caribou    Lewiston Design Design Dry-Bulb Wet-Bulb °C 5% °C 5% 29 23 31 23 31 24 32 24 31 23 31 24 31 24 31 23 31 24 30 31 31 30 32 31 32 23 24 24 23 24 24 24 31 31 30 31 31 31 30 30 31 32 31 29 31 31 32 30 24 24 24 24 24 24 23 23 24 24 24 23 24 24 24 24 33 34 35 36 34 34 34 35 36 34 25 24 22 24 24 22 20 24 23 22 33 34 35 36 34 36 24 24 24 24 24 24 32 32 32 31 24 24 24 23 32 31 32 32 33 33 24 24 24 25 25 25 33 33 33 33 33 33 34 34 34 32 34 26 26 26 26 26 26 26 26 26 26 26 28 27 26 28 21 21 19 21 FIG 11-3a (Cont’d) Dry Bulb/Wet Bulb Temperature Data2 U.S State and Stations    Millinocket    Portland    Waterville MARYLAND    Baltimore AP    Baltimore CO    Cumberland    Frederick    Hagerstown    Salisbury MASSACHUSETTS    Boston    Clinton    Fall River    Framingham    Gloucester    Greenfield    Lawrence    Lowell    New Bedford    Pittsfield    Springfield,     Westover AFB    Taunton    Worcester MICHIGAN    Adrian    Alpena    Battle Creek    Benton Harbor    Detroit    Escanaba    Flint    Grand Rapids    Holland    Jackson    Kalamazoo    Lansing    Marquette    Mt Pleasant    Muskegon    Pontiac    Port Huron    Saginaw    Sault St Marie    Traverse City    Ypsilanti MINNESOTA    Albert Lea    Alexandria    Bemidji    Brainerd    Duluth    Fairbault    Fergus Falls    International Falls    Mankato    Minneapolis/St Paul    Rochester    St Cloud    Virginia    Willmar    Winona MISSISSIPPI    Biloxi, Keesler AFB    Clarksdale    Columbus AFB    Greenville AFB    Greenwood    Hattiesburg    Jackson    Laurel    McComb    Meridian    Natchez    Tupelo    Vicksburg MISSOURI    Cape Girardeau    Columbia Design Design Dry-Bulb Wet-Bulb °C 5% °C 5% 27 20 27 21 27 21 32 31 31 31 32 31 24 24 24 24 24 24 29 29 27 28 28 28 29 29 27 27 22 22 22 22 22 22 23 23 22 21 29 28 27 22 23 21 29 28 29 29 30 27 29 29 28 29 29 29 25 29 28 29 28 29 25 28 30 23 21 23 22 23 21 22 22 22 23 23 22 20 22 22 23 23 22 20 22 22 29 29 27 29 26 29 29 27 29 30 29 29 27 29 29 23 22 21 22 20 23 22 20 23 23 23 22 20 22 23 32 33 33 33 33 33 34 33 33 34 33 33 34 27 26 26 26 26 26 26 26 26 26 26 26 26 33 33 25 24 U.S State and Stations    Farmington    Hannibal    Jefferson City    Joplin    Kansas City    Kirksville    Mexico    Moberly    Poplar Bluff    Rolla    St Joseph    St Louis AP    St Louis CO    Sedalia,     Whiteman AFB    Sikeston    Springfield MONTANA    Billings    Bozeman    Butte    Cut Bank    Glasgow    Glendive    Great Falls    Havre    Helena    Kalispell    Lewiston    Livingston    Miles City    Missoula NEBRASKA    Beatrice    Chadron    Columbus    Fremont    Grand Island    Hastings    Kearney    Lincoln    McCook    Norfolk    North Platte    Omaha    Scottsbluff    Sidney NEVADA    Carson City    Elko    Ely    Las Vegas    Lovelock    Reno AP    Reno CO    Tonopah    Winnemucca NEW HAMPSHIRE    Berlin    Claremont    Concord    Keene    Laconia    Manchester,     Grenier AFB    Portsmouth,     Pease AFB NEW JERSEY    Atlantic City    Long Branch    Newark    New Brunswick    Paterson    Phillipsburg    Trenton    Vineland NEW MEXICO    Alamogordo,      Holloman AFB    Albuquerque Design Design Dry-Bulb Wet-Bulb °C 5% °C 5% 32 24 32 25 33 24 34 24 34 24 32 24 33 24 33 24 33 26 32 24 33 25 33 24 33 24 32 24 33 33 25 24 31 29 27 28 29 32 29 31 29 29 28 29 33 29 18 16 14 16 18 18 16 18 16 17 17 16 19 17 33 33 33 33 33 33 32 33 33 32 32 31 32 32 24 20 24 24 23 23 22 24 22 24 22 24 19 19 32 32 29 40 34 32 33 32 33 16 16 14 21 18 16 16 16 16 27 28 29 28 28 21 22 22 22 22 29 22 28 22 30 31 31 30 31 30 29 30 24 24 24 24 24 23 24 24 34 33 19 18 U.S State and Stations    Artesia    Carlsbad    Clovis    Farmington    Gallup    Grants    Hobbs    Las Cruces    Los Alamos    Raton    Roswell,     Walker AFB    Santa Fe    Silver City    Socorro    Tucumcari NEW YORK    Albany AP    Albany CO    Auburn    Batavia    Binghamton    Buffalo    Cortland    Dunkirk    Elmira    Geneva    Glen Falls    Gloversville    Hornell    Ithaca    Jamestown    Kingston    Lockport    Massena    Newburg     Stewart AFB    NYC-Central Park    NYC-Kennedy AP    NYC-LaGuardia AP    Niagara Falls    Olean    Oneonta    Oswego    Plattsburg AFB    Poughkeepsie    Rochester    Rome-Griffiss AFB    Schenectady    Suffolk County AFB    Syracuse    Utica    Watertown NORTH CAROLINA    Asheville    Charlotte    Durham    Elizabeth City    Fayetteville,     Pope AFB    Goldsboro, Seymour    Johnson AFB    Greensboro    Greenville    Henderson    Hickory    Jacksonville    Lumberton    New Bern    Raleigh/Durham    Rocky Mount    Wilmington    Winston-Salem NORTH DAKOTA    Bismark    Devil’s Lake    Dickinson    Fargo    Grand Forks    Jamestown 11-5 Design Design Dry-Bulb Wet-Bulb °C 5% °C 5% 36 21 36 21 33 19 33 18 30 16 29 16 36 21 34 19 29 16 31 17 36 21 30 33 34 35 16 17 18 20 29 29 29 29 27 28 28 28 28 29 28 28 28 28 28 29 29 27 22 22 22 22 21 22 22 22 22 22 22 22 22 22 22 23 23 21 29 31 29 31 29 27 27 27 27 30 29 28 29 27 29 28 27 23 23 23 23 23 22 21 22 21 23 22 22 22 23 22 22 22 29 33 32 32 32 22 24 24 26 25 32 25 32 32 32 31 31 32 31 32 32 32 32 24 25 25 23 26 25 26 24 25 26 23 31 29 31 29 29 31 21 21 20 22 21 22 U.S State and Stations    Minot    Williston OHIO    Akron-Canton    Ashtabula    Athens    Bowling Green    Cambridge    Chillicothe    Cincinnati    Cleveland    Columbus    Dayton    Defiance    Findlay    Fremont    Hamilton    Lancaster    Lima    Mansfield    Marion    Middletown    Newark    Norwalk    Portsmouth    Sandusky    Springfield    Steubenville    Toledo    Warren    Wooster    Youngstown    Zanesville OKLAHOMA    Ada    Altus AFB    Ardmore    Bartlesville    Chickasha    Enid-Vance AFB    Lawton    McAlester    Muskogee    Norman    Oklahoma City    Ponca City    Seminole    Stillwater    Tulsa    Woodward OREGON    Albany    Astoria    Baker    Bend    Corvallis    Eugene    Grants Pass    Klamath Falls    Medford    Pendleton    Portland AP    Portland CO    Roseburg    Salem    The Dalles PENNSYLVANIA    Allentown    Altoona    Butler    Chambersburg    Erie    Harrisburg    Johnstown    Lancaster    Meadville    New Castle    Philadelphia    Pittsburgh AP    Pittsburgh CO Design Design Dry-Bulb Wet-Bulb °C 5% °C 5% 30 20 29 20 29 28 32 30 31 32 31 30 31 30 31 31 29 31 31 31 29 31 31 32 29 32 31 31 29 29 29 29 29 31 22 22 23 23 24 23 23 23 23 23 23 23 23 23 23 23 23 23 23 23 23 24 23 23 22 23 22 22 22 24 35 37 35 35 35 36 36 34 35 34 35 34 34 34 35 34 24 24 24 24 24 24 24 24 25 24 24 24 24 24 25 24 30 20 30 29 30 30 34 29 33 32 27 28 31 29 29 19 17 16 16 19 19 20 16 19 17 19 19 19 19 19 30 29 29 31 28 31 27 31 28 30 31 29 30 23 22 23 24 22 24 21 24 22 23 24 22 22 FIG 11-3a (Cont’d) Dry Bulb/Wet Bulb Temperature Data2 Design Design Dry-Bulb Wet-Bulb °C 5% °C 5%    Reading 30 23    Scranton/Wilkes-Barre 29 22    State College 29 22    Sunbury 30 23    Uniontown 29 23    Warren 28 22    West Chester 30 24    Williamsport 30 23    York 31 24 RHODE ISLAND    Newport 28 23    Providence 28 23 SOUTH CAROLINA    Anderson 32 24    Charleston AFB 32 26    Charleston 32 26    Columbia 34 25    Florence 32 26    Georgetown 31 26    Greenville 32 24    Greenwood 33 24    Orangeburg 34 25    Rock Hill 33 24    Spartanburg 32 24    Sumter-Shaw AFB 32 25 SOUTH DAKOTA    Aberdeen 31 23    Brookings 32 23    Huron 32 23    Mitchel 32 23    Pierre 33 22    Rapid City 32 19    Sioux Falls 31 23    Watertown 31 23    Yankton 31 23 TENNESSEE    Athens 32 24    Bristol-Tri City 31 23    Chattanooga 33 24    Clarksville 32 24    Columbia 33 24    Dyersburg 33 26    Greenville 31 23    Jackson 33 25    Knoxville 32 24    Memphis 34 26    Murfreesboro 33 24    Nashville 33 24 U.S State and Stations U.S State and Stations    Tullahoma TEXAS    Abilene    Alice    Amarillo    Austin    Bay City    Beaumont    Beeville    Big Springs    Brownsville    Brownwood    Bryan    Corpus Christi    Corsicana    Dallas    Del Rio,      Laughlin AFB    Denton    Eagle Pass    El Paso    Fort Worth    Galveston    Greenville    Harlingen    Houston AP    Houston CO    Huntsville    Killeen-Gray AFB    Lamesa    Laredo    Longview    Lubbock    Lufkin    McAllen    Midland    Mineral Wells    Palestine    Pampa    Pecos    Plainview    Port Arthur    San Angelo,     Goodfellow AFB    San Antonio    Sherman Perrin AFB    Snyder    Temple Design Design Dry-Bulb Wet-Bulb °C 5% °C 5% 33 24 36 35 34 36 33 33 35 35 33 36 34 33 36 36 23 26 21 25 26 27 26 22 26 24 26 26 25 25 36 36 37 36 36 31 36 34 33 34 36 35 34 37 35 34 34 34 36 36 36 34 36 34 33 24 24 25 20 24 27 24 26 26 26 25 24 22 25 26 22 26 26 22 24 26 21 22 21 27 36 36 35 36 36 23 24 24 22 25 U.S State and Stations    Tyler    Vernon    Victoria    Waco    Wichita Falls UTAH    Cedar City    Logan    Moab    Ogden    Price    Provo    Richfield    St George    Salt Lake City    Vernal VERMONT    Barre    Burlington    Rutland VIRGINIA    Charlottesville    Danville    Fredericksburg    Harrisonburg    Lynchburg    Norfolk    Petersburg    Richmond    Roanoke    Staunton    Winchester WASHINGTON    Aberdeen    Bellingham    Bremerton    Ellensburg    Everett-Paine AFB    Kennewick    Longview    Moses Lake,     Larson AFB    Olympia    Port Angeles    Seattle-Boeing Fld    Seattle CO    Seattle-Tacoma AP    Spokane Design Design Dry-Bulb Wet-Bulb °C 5% °C 5% 35 26 36 24 34 26 36 25 37 24 32 31 36 31 32 34 32 37 33 30 17 17 17 18 17 18 17 19 18 17 26 28 27 21 22 22 31 32 32 31 31 32 32 32 31 31 31 24 24 24 23 24 25 25 25 23 23 24 23 23 24 31 23 33 27 32 17 17 17 17 17 19 19 18 26 19 25 26 24 31 18 16 18 18 17 17 U.S State and Stations    Tacoma     McChord AFB    Walla Walla    Wenatchee    Yakima WEST VIRGINIA    Beckley    Bluefield    Charleston    Clarksburg    Elkins    Huntington    Martinsburg    Morgantown    Parkersburg    Wheeling WISCONSIN    Appleton    Ashland    Beloit    Eau Claire    Fond du Lac    Green Bay    La Crosse    Madison    Manitowoc    Marinette    Milwaukee    Racine    Sheboygan    Stevens Point    Waukesha    Wausau WYOMING    Casper    Cheyenne    Cody    Evanston    Lander    Laramie    Newcastle    Rawlins    Rock Springs    Sheridan    Torrington Design Design Dry-Bulb Wet-Bulb °C 5% °C 5% 26 32 33 32 18 19 18 18 26 26 31 31 28 32 31 29 31 29 21 21 23 23 22 24 24 23 24 22 28 26 31 30 29 28 29 29 28 28 29 29 28 30 29 29 22 20 24 23 22 22 23 23 22 22 23 23 23 23 23 22 31 29 28 28 29 26 29 27 28 31 31 16 16 16 14 16 15 19 16 14 17 17 The dry bulb and wet bulb temperatures represent values which have been equalled or exceeded by 5% of the total hours during the months of June through September in the northern hemisphere and the months December through March in the southern hemisphere The data for Canadian stations are based on the month of July only AP = airport AFB = air force base CO = urban offices Adapted to SI with permission of the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Atlanta, Georgia, from the 1993 ASHRAE Handbook—Fundamentals 11-6 FIG 11-3b Dry Bulb/Wet Bulb Temperature Data2 Country and Station ADEN Aden AFGHANISTAN Kabul ALGERIA Algiers ARGENTINA Buenos Aires Córdoba Tucuman AUSTRALIA Adelaide Alice Springs Brisbane Darwin Melbourne Perth Sydney AUSTRIA Vienna AZORES Lajes (Terceira) BAHAMAS Nassau BELGIUM Brussels BELIZE Belize BERMUDA Kindley AFB BOLIVIA La Paz BRAZIL Belem Belo Horizonte Brazilia Curitiba Fortaleza Porto Alegre Recife Rio de Janeiro Salvador São Paulo BULGARIA Sofia BURMA Mandalay Rangoon CAMBODIA Phnom Penh CANADA (Alberta) Calgary Edmonton Grande Prairie Jasper Lethbridge McMurray Medicine Hat Red Deer CANADA (British Columbia) Dawson Creek Fort Nelson Kamloops Nanaimo New Westminster Penticton Prince George Prince Rupert Trail Design Design Dry-Bulb Wet-Bulb °C 5% °C 5% 37 28 34 18 32 24 30 34 36 24 23 23 33 38 30 33 30 34 27 20 22 24 27 20 23 22 28 19 25 22 31 26 25 19 32 27 29 26 20 13 31 28 30 28 32 32 30 32 30 28 26 24 24 23 26 24 25 26 26 23 29 21 38 35 34 27 28 28 26 26 26 25 29 26 31 26 17 18 17 17 18 18 19 18 24 26 31 25 26 31 25 16 30 17 18 18 18 19 19 17 14 18 Country and Station Vancouver Victoria CANADA (Manitoba) Brandon Churchill Dauphin Flin Flon Portage la Prairie The Pas Winnepeg CANADA (New Brunswick) Campbellton Chatham Edmundston Fredericton Moncton Saint John CANADA (Newfoundland) Corner Brook Gander Goose Bay St John’s Stephenville CANADA (Northwest Terr.) Fort Smith Frobisher Inuvik Resolute Yellowknife CANADA (Nova Scotia) Amherst Halifax Kentville New Glasgow Sydney Truro Yarmouth CANADA (Ontario) Belleville Chatham Cornwall Hamilton Kapuskasing Kenora Kingston Kitchener London North Bay Oshawa Ottawa Owen Sound Peterborough St Catharines Sarnia Sault Ste Marie Sudbury Thunder Bay Timmins Toronto Windsor CANADA (Prince Edward Island) Charlottetown Summerside Design Design Dry-Bulb Wet-Bulb °C 5% °C 5% 23 21 19 16 28 23 27 26 28 26 29 21 17 21 19 22 20 22 26 28 27 28 26 24 20 21 21 21 21 19 22 25 25 23 22 18 19 18 19 18 26 15 24 11 23 18 11 16  8 17 26 23 27 25 25 26 21 20 19 21 21 20 21 18 28 29 29 28 27 27 28 28 28 26 29 29 27 28 28 29 26 27 27 27 29 30 23 23 22 23 21 21 23 22 23 20 23 22 21 22 23 23 21 20 20 20 23 23 24 25 20 20 Country and Station CANADA (Quebec) Bagotville Chicoutimi Drummondville Granby Hull Mégantic Montréal Québec Rimouski St Jean St Jéirome Sept Iles Shawnigan Sherbrooke Thetford Mines Trois Riviéres Val d’Or Valleyfield CANADA (Saskatchewan) Estevan Moose Jaw North Battleford Prince Albert Regina Saskatoon Swift Current Yorkton CANADA (Yukon Territory) Whitehorse CEYLON Colombo CHILE Punta Arenas Santiago Valparaiso CHINA Chungking Shanghai COLOMBIA Baranquilla Bogotá Cali Medellin CONGO Brazzaville Kinshasa (Leopoldville) Stanleyville CUBA Guantanamo Bay Havana CZECHOSLOVAKIA Prague DENMARK Copenhagen DOMINICAN REPUBLIC Santo Domingo ECUADOR Guayacil Quito EL SALVADOR San Salvador ETHIOPIA Addis Ababa Asmara FINLAND Helsinki 11-7 Design Design Dry-Bulb Wet-Bulb °C 5% °C 5% 27 27 28 28 29 27 28 27 24 29 28 21 28 27 27 28 27 29 20 20 22 22 22 22 22 21 19 22 22 17 22 22 22 22 20 22 30 30 28 27 29 28 31 27 21 20 19 19 20 19 19 20 23 14 31 27 18 31 25 12 21 18 35 32 26 27 34 21 26 29 28 14 20 22 33 32 27 27 32 27 33 32 27 27 28 18 23 18 31 27 32 22 26 17 35 24 27 27 18 17 22 17 Country and Station FRANCE Lyon Marseilles Nantes Nice Paris Strasbourg FRENCH GUIANA Cayenne GERMANY Berlin Hamburg Hannover Mannheim Munich GHANA Accra GIBRALTER Gibralter GREECE Athens Thessaloniki GREENLAND Narssarssuaq GUATEMALA Guatemala City GUYANA Georgetown HAITI Port au Prince HONDURAS Tegucigalpa HONG KONG Hong Kong HUNGARY Budapest ICELAND Reykjavik INDIA Ahmenabad Bangalore Bombay Calcutta Madras Nagpur New Delhi INDONESIA Djakarta Kupang Makassar Medan Palembang Surabaya IRAN Abadan Meshed Tehran IRAQ Baghdad Mosul IRELAND Dublin Shannon ISRAEL Jerusalem Tel Aviv ITALY Milan Naples Rome IVORY COAST Abidjan Design Design Dry-Bulb Wet-Bulb °C 5% °C 5% 30 29 27 28 28 27 21 21 19 22 19 19 32 28 26 23 24 28 27 19 18 18 20 18 32 26 30 23 33 33 22 24 16 11 27 19 31 26 34 27 29 22 32 27 29 21 13 12 41 34 33 36 38 42 41 26 23 27 28 28 26 28 31 33 31 32 32 32 26 27 26 26 26 26 43 34 37 27 19 23 42 43 22 22 21 22 17 17 33 33 21 22 29 30 32 23 22 22 31 27 FIG 11-3b (Cont’d) Dry Bulb/Wet Bulb Temperature Data2 Country and Station JAPAN Fukuoka Sapporo Tokyo JORDAN Amman KENYA Nairobi KOREA Pyongyang Seoul LEBANON Beirut LIBERIA Monrovia LIBYA Bengasi MADAGASCAR Tananarive MALAYSIA Kuala Lumpur Penang Singapore MARTINIQUE Fort de France MEXICO Guadalajara Mérida Mexico City Monterrey Vera Cruz MOROCCO Casablanca NEPAL Katmandu NETHERLANDS Amsterdam NEW GUINEA Manokwari Point Moresby Design Design Dry-Bulb Wet-Bulb °C 5% °C 5% 32 27 31 26 22 26 33 20 26 18 29 31 24 26 32 24 31 27 33 24 28 22 33 33 32 27 27 27 31 27 32 34 26 34 31 19 25 15 25 28 30 21 30 24 23 17 31 32 27 26 Country and Station NEW ZEALAND Auckland Christ Church Wellington NICARAGUA Managua NIGERIA Lagos NORWAY Bergen Oslo PAKISTAN Chittagong Karachi Lahore Peshwar PANAMA & CANAL ZONE Panama City PARAGUAY Asunción PERU Lima PHILIPPINES Manila POLAND Kraków Warsaw PORTUGAL Lisbon PUERTO RICO San Juan RUMANIA Bucharest SAUDI ARABIA Dhahran Jedda Riyadh SENEGAL Dakar Design Design Dry-Bulb Wet-Bulb °C 5% °C 5% 24 24 22 18 19 18 33 26 32 27 23 23 18 18 32 35 41 39 27 27 27 26 33 27 36 27 29 23 33 27 26 26 19 20 28 19 31 26 32 21 42 38 41 29 28 24 33 27 Country and Station SOMALIA Mogadiscio SOUTH AFRICA Capetown Johannesburg Pretoria SOVIET UNION Alma Ata Archangel Kaliningrad Krasnoyarsk Kiev Kharkov Kuibyshev Leningrad Minsk Moscow Odessa Petropavlovsk Rostov on Don Sverdlovsk Tashkent Tblisi Vladivostok Volgograd SPAIN Barcelona Madrid Valencia SUDAN Khartoum SURINAM Paramaribo SWEDEN Stockholm SWITZERLAND Zurich SYRIA Damascus Design Design Dry-Bulb Wet-Bulb °C 5% °C 5% 32 27 30 27 29 21 21 20 28 20 25 24 27 28 27 22 23 26 28 18 29 22 32 28 23 30 19 14 18 16 19 19 19 17 18 18 20 13 20 16 21 19 20 21 29 32 31 23 19 23 40 24 32 27 22 16 26 19 37 21 Country and Station TAIWAN Tainan Taipei TANZANIA Dar es Salaam THAILAND Bangkok TRINIDAD Port of Spain TUNISIA Tunis TURKEY Adana Ankara Istanbul Izmir UNITED ARAB REPUBLIC Cairo UNITED KINGDOM Belfast Birmingham Cardiff Edinburgh Glasgow London URUGUAY Montevideo VENEZUELA Caracas Maracaibo VIET NAM Da Nang Hanoi Saigon YUGOSLAVIA Belgrade Design Design Dry-Bulb Wet-Bulb °C 5% °C 5% 32 32 28 27 31 27 34 27 32 26 36 23 35 32 30 34 25 19 23 23 37 23 21 23 23 20 20 24 17 17 17 16 16 18 29 22 27 35 21 28 34 35 32 29 29 28 30 22 The dry bulb and wet bulb temperatures represent values which have been equalled or exceeded by 5% of the total hours during the months of June through September in the northern hemisphere and the months December through March in the southern hemisphere The data for Canadian stations are based on the month of July only AP = airport AFB = air force base CO = urban offices Adapted to SI with permission of the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Atlanta, Georgia, from the 1993 ASHRAE Handbook—Fundamentals 11-8 Tower Location The open recirculating system routes cooled water through the heat-exchange equipment Effluent warm water then is cooled by contact with air in a cooling tower The cooling effect is produced by evaporation of a portion of the circulating water, and this evaporation causes the dissolved solids in the water to become concentrated Water lost by evaporation must be replaced by makeup water But water lost through entrainment of droplets in the circulating air (windage or drift) tends to limit the degree of concentration since the entrained droplets also contain dissolved solids Windage loss varies with the type of tower Local heat sources upwind of the cooling tower can elevate the wet-bulb temperature of the air entering the tower Interference occurs when a portion of the saturated air upwind of the tower contaminates the ambient air of a downwind tower Drift and condensed water can cause corrosion problems with downwind equipment PERFORMANCE CHARACTERISTICS The performance characteristics of various types of towers will vary with height, fill configuration, and flow arrangement — crossflow or counterflow; however, these factors have been taken into consideration in preparation of the Performance Characteristic Nomograph Fig. 11-5 When accurate characteristics of a specific tower are required, the cooling tower manufacturer should be consulted Typical windage losses, expressed as percentages of the total system water circulation rate, for different evaporative equipment are as follows: Spray ponds 1.0 to 5.0% Atmospheric-draft towers 0.3 to 1.0% Mechanical-draft towers 0.1 to 0.3% FIG 11-4 Cooling System Characteristics 11-9 Example 11-1 — Effect of Varying WB Temperature on Cold Water Temperature (CWT) What is new CWT when WB changes from 25° to 15° with m3/h and range remaining constant? Enter Nomograph at 30° CWT, go horizontally to 25° WB, then vertically down to 15° WB, read new CWT of 24° Example 11-2 — Effect of Varying Cooling Range on Cold Water Temperature What is new CWT when cooling range is changed from 10° to 15° (50% increase in heat load) with m3/h and WB held constant? Enter Nomograph at 30° CWT, go horizontally to 25° WB, vertically to 10° R, horizontally to 15° R, vertically downward to 25° WB, read new CWT 31.8° Example 11-3 — Effect of Varying Water Circulating Rate and Heat Load on Cold Water Temperature What is new CWT when water circulation is changed from 200 m3/h to 300 m3/h (50% change in heat load at constant Range) Varying water rate, particularly over wide ranges, may require modifications to the distribution system Enter Nomograph at 30° CWT, go horizontally to 25° WB, vertically to 10° R, horizontally to Performance Factor of 1.8 Obtain new PF by multiplying (1.8) (300/200) = 2.7, then enter Nomograph at PF of 2.7, go horizontally to 10° R, vertically down to 25° WB, read new CWT 33.2° 11-10 Example 11-4 — Effect of Varying WB Temperature, Range, and Water Circulating Rate on Cold Water Temperature What is new CWT when the WB changes from 25° to 15°, R changes from 10° to 12.5°, m3/h changes from 200 to 250 (25% change in heat load.) Enter Nomograph at 30° CWT, go horizontally to 25° WB, vertically to 10° R, horizontally read PF 1.8 then multiply (1.8) (250/200) = 2.25 (new PF) Enter Nomograph at PF = 2.25, go horizontally to 12.5° R, vertically down to 15° WB, read 27.5° new CWT Example 11-5 — Effect of Varying Fan HP Input on Cold Water Temperature What is new CWT if motor is changed from 30 kW to 35 kW in Example 11-4? The air flow rate varies as the cube root of the horsepower and performance varies almost directly with the ratio of water rate to air rate, therefore the change in air flow rate can be applied to the Performance Factor Increasing the air flow rate (by installing a larger motor) decreases the Performance Factor PF correction factor = (35/30)1/3 = 1.053 Divide PF by PF correction factor to get new PF Applying this to Example 11-4, we get 2.25/1.053 = 2.14 Enter Nomograph at 2.14 PF (instead of 2.25 PF) go horizontally to 12.5° R, vertically down to 15° WB, read 27.2° CWT Performance tests on a cooling tower should be done in accordance with the Cooling Tower Institute (CTI) Acceptance Test Code and the American Society of Mechanical Engineers (ASME) test code Examples ample 11-5), m3/h could be increased from 250 to (250) (1.053) = 263 m3/h Example 11-7 — Calculate the concentrations and blowdown rate for the following cooling tower: Circulation Rate = 2000 m3/h The use of the Nomograph is illustrated by the following examples covering typical changes in operating conditions Water Temperature Drop Through Tower = 10°C Type of Tower = Mechanical Induced Draft Assume a cooling tower is operating at known conditions of: Flow Blowdown Rate = 4.0 m3/h, or 0.2% of circulation rate = 200 m3/h Therefore: Hot Water = 40°C Evaporation Loss = 1.8% (1% for each 5.5°C temperature drop) Cold Water = 30°C Wet Bulb = 25°C This is commonly referred to as 40-30-25 or 10° Range (40° – 30°) and 5° Approach (30° – 25°) Example 11-6 — The correction factor shown in Example 11-5 could also be used to increase m3/h instead of decreasing CWT, as was done in Example 11-5 In Example 11-4, we developed a new CWT of 27.5° when circulating 250 m3/h at 12.5° R and 15° WB If motor kW is increased from 30 to 35 under these conditions with PF correction factor = 1.053 (as shown in Ex- (all rates are based on a percent of circulation rate) Windage Loss = 0.3% (maximum for mechanical draft tower, p. 11-2) 11-11 Number of E+B Concentrations (cycles) = B 1.8 + (0.2 + 0.3) = = 4.6 (0.2 + 0.3) FIG 11-5 Performance Characteristic Nomograph 11-12 If the resultant concentrations are excessive and a desired concentration of 4.0 is required, what must the blowdown rate be? E B = Cycles – 1.8 = = 0.6% 4.0 – The windage component of B is 0.3%, therefore the blowdown rate required would be 0.6 – 0.3 = 0.3% or (2000 m3/h) (0.003) = 6.0 m3/h CONCENTRATION CYCLES The concentration of compounds occurring in circulating water systems that can cause scaling or corrosion of equipment must be controlled at a desirable level This concentration level, developed on each system, is based on the quality of makeup water and the water treating chemicals used to control corrosion or scaling The concentration is usually reported as concentration cycles and refers to the number of times the compounds in the makeup water are concentrated in the blowdown water For example, if the concentration in the makeup water were 125 mg/kg and the concentration of the blowdown were 500, the concentration cycles would be 500/125 or cycles The compounds are concentrated by the loss of water through evaporation and windage The evaporation loss in a cooling tower is calculated from the ratio of specific heat to the heat of vaporation The specific heat of water is 4.186 kJ/(kg • °C) and the heat of vaporation is 2326 kJ/kg The ratio 4.186/2326 = 0.0018/°C indicates that 0.18% evaporation occurs for every degree of cooling taking place across the tower Mechanical Draft Towers Fans are used to move the air through the mechanical draft tower The performance of the tower has a greater stability because it is affected by fewer psychrometric variables The fans provide a means of regulating the air flow Mechanical draft towers are characterized as either forced draft or induced draft Forced draft towers (Fig. 11-6) — The fan is located on the air stream entering the tower This tower is characterized by high air entrance velocities and low exit velocities, therefore, the towers are susceptible to recirculation thus having a lower performance stability The fans can also be subject to icing under conditions of low ambient temperature and high humidity Induced draft towers (Fig. 11-7a and 11-7b) — The fan is located on the air stream leaving the tower This causes air exit velocities which are three to four times higher than their air entrance velocities This improves the heat dispersion and reduces the potential for recirculation Induced draft towers require about one kw of input for every 18 000 m3/h of air.3 FIG 11-7a Mechanical Induced Draft Counterflow Tower Air Out Fan TYPES OF COOLING TOWERS Water Inlet Cooling towers have two types of air flow: crossflow and counterflow In crossflow towers, the air moves horizontally across the downward flow of water In counterflow towers, the air moves vertically upward against the downward fall of the water There are many types and sizes of cooling towers: Watet Outlet FIG 11-6 FIG 11-7b Mechanical Forced Draft Counterflow Tower Water Sprays Air In Air In Mechanical Induced Draft Cross Flow Tower Air Out Air Out Fan Air In Water In Air In Fan Water Out Water Out 11-13 Air In Coil shed towers (Fig. 11-8) — This application exists in many older cooling towers The atmospheric coils or sections are located in the basin of the cooling tower The sections are cooled by flooding the surface of the coils with cold water Reasons for discontinued use were scaling problems, poor temperature control, and construction costs This type tower can exist both as mechanical or natural draft ENVIRONMENTAL Environmental factors should be considered when choosing whether or not to use a cooling tower Areas to consider would include: Leakage to the atmosphere (VOC, CO2) Particulate matter (mist eliminators) Natural Draft Towers Tower blowdown (disposal well, treatment, release to surface waters, evaporation ponds) Atmospheric spray towers (Fig. 11-9) — Cooling towers of this type are dependent upon atmospheric conditions No mechanical devices are used to move the air They are used when small sizes are required and when low performance can be tolerated Hyperbolic natural draft towers (Fig. 11-10) — These towers are extremely dependable and predictable in their thermal performance A chimney or stack is used to induce air movement through the tower These issues are discussed further in Section 18 — Utilities BASIN The cooling tower basin design should take into consideration the suction requirements for the water circulation pump This is discussed in more detail in the “Submergence” section under the title “Net Positive Suction Head” in Section 12 — Pumps and Hydraulic Turbines SALTWATER COOLING TOWERS4 FIG 11-8 Mechanical Draft Coil Shed Tower Air Outlet Gear Drive Air Inlet Fill Drift Eliminators Water Inlet Fan Air Inlet Fill In some parts of the world, where fresh water is not in sufficient supply for a cooling tower, salt water can be used in place of fresh water This would include sea water, brackish water and produced water Salt water has a 4-8% performance penalty compared to fresh water Salt water cooling towers cost 35-50% more than fresh water cooling towers This is due to the performance penalty (larger tower required) and materials of construction (corrosion avoidance) Concentration cycles are reduced to around 1.5 Corrosion of nearby equipment and structures due to drift is also a concern FIG 11-10 Coils Hyperbolic Natural Draft Tower Air Outlet Water Outlet FIG 11-9 Atmospheric Spray Tower Air Outlet Water Inlet Distribution System Air In Air Inlet Air In Hot Water Inlet Water Outlet Water Outlet Cold Water Collection Basin 11-14 FIG 11-11 Properties of Saturated Air1 °C Hum Ratio kgw/kga Ws –60 –59 –58 –57 –56 –55 –54 –53 –52 –51 –50 –49 –48 –47 –46 –45 –44 –43 –42 –41 –40 –39 –38 –37 –36 –35 –34 –33 –32 –31 –30 –29 –28 –27 –26 –25 –24 –23 –22 –21 –20 –19 –18 –17 –16 –15 –14 –13 –12 –11 –10 –9 –8 –7 –6 –5 –4 –3 –2 –1 10 11 12 13 14 15 16 0.0000067 0.0000076 0.0000087 0.0000100 0.0000114 0.0000129 0.0000147 0.0000167 0.0000190 0.0000215 0.0000243 0.0000275 0.0000311 0.0000350 0.0000395 0.0000445 0.0000500 0.0000562 0.0000631 0.0000708 0.0000793 0.0000887 0.0000992 0.0001108 0.0001237 0.0001379 0.0001536 0.0001710 0.0001902 0.0002113 0.0002346 0.0002602 0.0002883 0.0003193 0.0003533 0.0003905 0.0004314 0.0004762 0.0005251 0.0005787 0.0006373 0.0007013 0.0007711 0.0008473 0.0009303 0.0010207 0.0011191 0.0012262 0.0013425 0.0014690 0.0016062 0.0017551 0.0019166 0.0020916 0.0022811 0.0024862 0.0027081 0.0029480 0.0032074 0.0034874 0.003789 0.004076 0.004381 0.004707 0.005054 0.005424 0.005818 0.006237 0.006683 0.007157 0.007661 0.008197 0.008766 0.009370 0.010012 0.010692 0.011413 Temp va Volume m3/kg dry air vas vs 0.6027 0.6056 0.6084 0.6113 0.6141 0.6170 0.6198 0.6226 0.6255 0.6283 0.6312 0.6340 0.6369 0.6397 0.6426 0.6454 0.6483 0.6511 0.6540 0.6568 0.6597 0.6625 0.6653 0.6682 0.6710 0.6739 0.6767 0.6796 0.6824 0.6853 0.6881 0.6909 0.6938 0.6966 0.6995 0.7023 0.7052 0.7080 0.7109 0.7137 0.7165 0.7194 0.7222 0.7251 0.7279 0.7308 0.7336 0.7364 0.7393 0.7421 0.7450 0.7478 0.7507 0.7535 0.7563 0.7592 0.7620 0.7649 0.7677 0.7705 0.7734 0.7762 0.7791 0.7819 0.7848 0.7876 0.7904 0.7933 0.7961 0.7990 0.8018 0.8046 0.8075 0.8103 0.8132 0.8160 0.8188 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 0.0002 0.0002 0.0002 0.0002 0.0003 0.0003 0.0003 0.0004 0.0004 0.0004 0.0005 0.0005 0.0006 0.0007 0.0007 0.0008 0.0009 0.0010 0.0011 0.0012 0.0013 0.0014 0.0016 0.0017 0.0019 0.0021 0.0023 0.0025 0.0028 0.0030 0.0033 0.0036 0.0039 0.0043 0.0047 0.0051 0.0055 0.0059 0.0064 0.0068 0.0074 0.0079 0.0085 0.0092 0.0098 0.0106 0.0113 0.0122 0.0131 0.0140 0.0150 0.6027 0.6056 0.6084 0.6113 0.6141 0.6170 0.6198 0.6227 0.6255 0.6284 0.6312 0.6341 0.6369 0.6398 0.6426 0.6455 0.6483 0.6512 0.6540 0.6569 0.6597 0.6626 0.6654 0.6683 0.6712 0.6740 0.6769 0.6798 0.6826 0.6855 0.6884 0.6912 0.6941 0.6970 0.6999 0.7028 0.7057 0.7086 0.7115 0.7144 0.7173 0.7202 0.7231 0.7261 0.7290 0.7320 0.7349 0.7379 0.7409 0.7439 0.7469 0.7499 0.7530 0.7560 0.7591 0.7622 0.7653 0.7685 0.7717 0.7749 0.7781 0.7813 0.7845 0.7878 0.7911 0.7944 0.7978 0.8012 0.8046 0.8081 0.8116 0.8152 0.8188 0.8225 0.8262 0.8300 0.8338 Enthalpy kJ/kg dry air has hs –60.351 –59.344 –58.338 –57.332 –56.326 –55.319 –54.313 –53.307 –52.301 –51.295 –50.289 –49.283 –48.277 –47.271 –46.265 –45.259 –44.253 –43.247 –42.241 –41.235 –40.229 –39.224 –38.218 –37.212 –36.206 –35.200 –34.195 –33.189 –32.183 –31.178 –30.171 –29.166 –28.160 –27.154 –26.149 –25.143 –24.137 –23.132 –22.126 –21.120 –20.115 –19.109 –18.103 –17.098 –16.092 –15.086 –14.080 –13.075 –12.069 –11.063 –10.057 –9.052 –8.046 –7.040 –6.035 –5.029 –4.023 –3.017 –2.011 –1.006 –0.000 1.006 2.012 3.018 4.024 5.029 6.036 7.041 8.047 9.053 10.059 11.065 12.071 13.077 14.084 15.090 16.096 0.017 0.018 0.021 0.024 0.028 0.031 0.036 0.041 0.046 0.052 0.059 0.067 0.075 0.085 0.095 0.108 0.121 0.137 0.153 0.172 0.192 0.216 0.241 0.270 0.302 0.336 0.375 0.417 0.464 0.517 0.574 0.636 0.707 0.782 0.867 0.959 1.059 1.171 1.292 1.425 1.570 1.729 1.902 2.092 2.299 2.524 2.769 3.036 3.327 3.642 3.986 4.358 4.764 5.202 5.677 6.192 6.751 7.353 8.007 8.712 9.473 10.197 10.970 11.793 12.672 13.610 14.608 15.671 16.805 18.010 19.293 20.658 22.108 23.649 25.286 27.023 28.867 –60.334 –59.326 –58.317 –57.308 –56.298 –55.288 –54.278 –53.267 –52.255 –51.243 –50.230 –49.216 –48.202 –47.186 –46.170 –45.151 –44.132 –43.111 –42.088 –41.063 –40.037 –39.007 –37.976 –36.942 –35.905 –34.864 –33.820 –32.772 –31.718 –30.661 –29.597 –28.529 –27.454 –26.372 –25.282 –24.184 –23.078 –21.961 –20.834 –19.695 –18.545 –17.380 –16.201 –15.006 –13.793 –12.562 –11.311 –10.039 –8.742 –7.421 –6.072 –4.693 –3.283 –1.838 –0.357 1.164 2.728 4.336 5.995 7.706 9.473 11.203 12.982 14.811 16.696 18.639 20.644 22.713 24.852 27.064 29.352 31.724 34.179 36.726 39.370 42.113 44.963 Temp °C 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 Hum Ratio kgw/kga Ws 0.012178 0.012989 0.013848 0.014758 0.015721 0.016741 0.017821 0.018963 0.020170 0.021448 0.022798 0.024226 0.025735 0.027329 0.029014 0.030793 0.032674 0.034660 0.036756 0.038971 0.041309 0.043778 0.046386 0.049141 0.052049 0.055119 0.058365 0.061791 0.065411 0.069239 0.073282 0.077556 0.082077 0.086858 0.091918 0.097272 0.102948 0.108954 0.115321 0.122077 0.129243 0.136851 0.144942 0.15354 0.16269 0.17244 0.18284 0.19393 0.20579 0.21848 0.23207 0.24664 0.26231 0.27916 0.29734 0.31698 0.33824 0.36130 0.38641 0.41377 0.44372 0.47663 0.51284 0.55295 0.59751 0.64724 0.70311 0.76624 0.83812 0.92062 1.01611 1.12800 1.26064 1.42031 va Volume m3/kg dry air vas vs 0.8217 0.8245 0.8274 0.8302 0.8330 0.8359 0.8387 0.8416 0.8444 0.8472 0.8501 0.8529 0.8558 0.8586 0.8614 0.8643 0.8671 0.8700 0.8728 0.8756 0.8785 0.8813 0.8842 0.8870 0.8898 0.8927 0.8955 0.8983 0.9012 0.9040 0.9069 0.9097 0.9125 0.9154 0.9182 0.9211 0.9239 0.9267 0.9296 0.9234 0.9353 0.9381 0.9409 0.9438 0.9466 0.9494 0.9523 0.9551 0.9580 0.9608 0.9636 0.9665 0.9693 0.9721 0.9750 0.9778 0.9807 0.9835 0.9863 0.9892 0.9920 0.9948 0.9977 1.0005 1.0034 1.0062 1.0090 1.0119 1.0147 1.0175 1.0204 1.0232 1.0261 1.0289 0.0160 0.0172 0.0184 0.0196 0.0210 0.0224 0.0240 0.0256 0.0273 0.0291 0.0311 0.0331 0.0353 0.0376 0.0400 0.0426 0.0454 0.0483 0.0514 0.0546 0.0581 0.0618 0.0657 0.0698 0.0741 0.0788 0.0837 0.0888 0.0943 0.1002 0.1063 0.1129 0.1198 0.1272 0.1350 0.1433 0.1521 0.1614 0.1713 0.1819 0.1932 0.2051 0.2179 0.2315 0.2460 0.2614 0.2780 0.2957 0.3147 0.3350 0.3568 0.3803 0.4055 0.4328 0.4622 0.4941 0.5287 0.5662 0.6072 0.6519 0.7010 0.7550 0.8145 0.8805 0.9539 1.0360 1.1283 1.2328 1.3518 1.4887 1.6473 1.8333 2.0540 2.3199 0.8377 0.8417 0.8457 0.8498 0.8540 0.8583 0.8627 0.8671 0.8717 0.8764 0.8811 0.8860 0.8910 0.8962 0.9015 0.9069 0.9125 0.9183 0.9242 0.9303 0.9366 0.9431 0.9498 0.9568 0.9640 0.9714 0.9792 0.9872 0.9955 1.0042 1.0132 1.0226 1.0323 1.0425 1.0532 1.0643 1.0760 1.0882 1.1009 1.1143 1.1284 1.1432 1.1588 1.1752 1.1926 1.2109 1.2303 1.2508 1.2726 1.2958 1.3204 1.3467 1.3749 1.4049 1.4372 1.4719 1.5093 1.5497 1.5935 1.6411 1.6930 1.7498 1.8121 1.8810 1.9572 2.0422 2.1373 2.2446 2.3666 2.5062 2.6676 2.8565 3.0800 3.3488 Enthalpy kJ/kg dry air has hs 17.102 18.108 19.114 20.121 21.127 22.133 23.140 24.146 25.153 26.159 27.165 28.172 29.179 30.185 31.192 32.198 33.205 34.212 35.219 36.226 37.233 38.239 39.246 40.253 41.261 42.268 43.275 44.282 45.289 46.296 47.304 48.311 49.319 50.326 51.334 52.341 53.349 54.357 55.365 56.373 57.381 58.389 59.397 60.405 61.413 62.421 63.429 64.438 65.446 66.455 67.463 68.472 69.481 70.489 71.498 72.507 73.516 74.525 75.535 76.543 77.553 78.562 79.572 80.581 81.591 82.600 83.610 84.620 85.630 86.640 87.650 88.661 89.671 90.681 30.824 32.900 35.101 37.434 39.908 42.527 45.301 48.239 51.347 54.638 58.120 61.804 65.699 69.820 74.177 78.780 83.652 88.799 94.236 99.983 106.058 112.474 119.258 126.430 134.005 142.007 150.475 159.417 168.874 178.882 189.455 200.644 212.485 225.019 238.290 252.340 267.247 283.031 299.772 317.549 336.417 356.461 377.788 400.458 424.624 450.377 477.837 507.177 538.548 572.116 608.103 646.724 688.261 732.959 781.208 833.335 889.807 951.077 1017.841 1090.628 1170.328 1257.921 1354.347 1461.200 1579.961 1712.547 1861.548 2029.983 2221.806 2442.036 2697.016 2995.890 3350.254 3776.918 47.926 51.008 54.216 57.555 61.035 64.660 68.440 72.385 76.500 80.798 85.285 89.976 94.878 100.006 105.369 110.979 116.857 123.011 129.455 136.209 143.290 150.713 158.504 166.683 175.265 184.275 193.749 203.699 214.164 225.179 236.759 248.955 261.803 275.345 289.624 304.682 320.596 337.388 355.137 373.922 393.798 414.850 437.185 460.863 486.036 512.798 541.266 571.615 603.995 638.571 675.566 715.196 757.742 803.448 852.706 905.842 963.323 1025.603 1093.375 1167.172 1247.881 1336.483 1433.918 1541.781 1661.552 1795.148 1945.158 2114.603 2307.436 2528.677 2784.666 3084.551 3439.925 3867.599 Reprinted by permission of the American Society of Heating, Refrigerating and AirConditioning Engineers, Atlanta, GA, from the 1993 ASHRAE Handbook—Fundamentals 11-15 REFERENCES AND BIBLIOGRAPHY American Society of Heating, Refrigerating and Air-Conditioning Engineers, “ASHRAE Handbook—Fundamentals,” Table 1, Chapter 6, Atlanta, Georgia Evans, Frank L., Jr., “Equipment Design Handbook for Refineries and Chemical Plants,” 2nd ed., Gulf Publishing Company, Houston, Texas Maulbetsch, John S and DeFilippo, Michael N., “Performance, Cost and Environmental Effects of Saltwater Cooling Towers.” American Society of Heating, Refrigerating and Air-Conditioning Engineers, “ASHRAE Handbook—Fundamentals,” Tables 1, and 3, Chapter 24, Atlanta, Georgia 11-16 ... Induced draft towers require about one kw of input for every 18 000 m3/h of air.3 FIG 11-7a Mechanical Induced Draft Counterflow Tower Air Out Fan TYPES OF COOLING TOWERS Water Inlet Cooling towers. .. Out 11-13 Air In Coil shed towers (Fig. 11-8) — This application exists in many older cooling towers The atmospheric coils or sections are located in the basin of the cooling tower The sections... water has a 4-8% performance penalty compared to fresh water Salt water cooling towers cost 35-50% more than fresh water cooling towers This is due to the performance penalty (larger tower required)