Document KJN5dvbyxRXEJNZe0p1pDaXXw

744 CHAPTER 34 1952 Guide Table 1. Average Maximum Water Main Temperatures* | T emp. F T emp. F State . City fa cu S State a H City State City Ala. Birmingham........... 84 Mobile...................... 80 Ark. little Rock 83 '-Aria. Phoenix.................... 82 Tucson--... !......... 80 Calif. Anaheim ............. 60 Berkeley.; .......... 69 Fresno...................... 80 Fullerton.............. 76 Glendale......... ...... 68 Loe Angeles............. 80 Oakland...:............. 69 Ontario.................... 70 Pasadena.................. 82 Pomona.................... 76 Riverside....... ........ 78 Sacramento............. 72 San Bernardino___ 66 ' San Diego................ 84 San Francisco......... 71 Whittier.................. '. 75 Colo. Denver........ ........ 75 Conn.- Bridgeport............... 66 Hartford.. ....... 73 New Haven............. 76 Waterburv; ........ 72 D. C. Washington..-; . 84- Del. Wilmington............. 83 . Fla. . Jacksonville............. 86 Miami ............... Tampa......... 8727. Ga. Atlanta..................... 85 Macon.!.... :.\___ 80 Idaho. Boise....................,.. 60 111. .Chicago.................... 78 Cicero...........1...... 76 Evanston :............. .73 Moline........ 83 Peoria......... 67 ' Rockford.................. 59 Springfield............... 82 Ind. Evansville............... 88 Gary.......................... 75 Indianapolis............ 84 South Bend............. 61 Terre Haute............ 82 Iowa Cedar Rapids......... 78 Des Moines............. 77 Sioux City............... 62 Hans. Concordia................ 57 Kansas City........... 86 Topeka..................... 88 Wichita........... ...... 72 Ky. Louisville................ 85 La. Baton Rouge.-......... 85 New Orleans........... 90 Shreveport............... 88 Me. Augusta.................... 60 Md. Baltimore....... ...... 75 Maas. Mich. Minn. Mo. Nebr. Nev. N. H. N. J. n. y. N. C. N. M. Ohio Okla. 80 Cambridge............... Fall River........ Lowell....................... Lynn......................... New Bedford.......... Salem...................... Worcester................. Detroit..................... 70 76 50 Pa. 68 70 . 68- 76 77 70 5 Eugene....... -Portland.................. Altoona........... i____ Johnstown*. McKeesport.'.,.. Philadelphia Pittsburgh___ 60 65 74 75 74. 82 85< 86' 84 S. C. 77 Jackson.................... 56 Spartanburg........... 78 Kalamazoo......... 53 S: D. Rapid City 64 .Tenn., 65 82 Duluth...*................ 55. Memphis..-. ........... 85 Minneapolis............. 85 Nashville................. 90 St. Paul........ ...... 80 Amarillo .. ....... 70 Jefferson City___ 82 Austin...................... 90 Kansas City....... 84 -Beaumont................ 86 Springfield............... 82 Dallas....... . x......... 86 St. Joseph................ 84 El Paso................... 85 St. Louis...'..!........ 85 Fort Worth1 :-- 85 Springfield............... 74- Galveston........... 90 Lincoln..................... 70 Omaha...................... H5 Houston........... Port Arthur:.... 83 83' Reno......................... 70 San Antonio........... 78 76 85 63 Utah- 44 75 65 78 Va. 75 79 73 68 80 Buffalo...................... 78 Richmond............... 85 56 Wash. 58- 74 62 New Rochelle......... 75 Spokane..*:......... 51 72 57 70 W. Va. 85 60 78 69 70 74 85 92 Winston-Salem....... 82 Albuquerque........... 65 PnovAkron........................ 76 1NCE Canton..................... 50 Cincinnati............... 84 77 84. B. C. 60 82 72 P.E.I. 83 Que. Oklahoma City___ 82 54 58 75 68 Quebec...................... 64 60 50 63 48 78 68 * These averages taken from various city water main locations, with some actual values slightly higher and some lower than values shown. Some values were supplied by H. E. Degler, Marley Company. Some were obtained from City Water Department records. The highest values given by the various authorities are usually those listed. bulb temperature, but the same humidity ratio, more water can be ab sorbed per pound of dry air in passing through the washer, assuming that the humidifying effectiveness of the washer is not adversely affected by operation at the higher wet-bulb temperature. The analysis of the process occurring in the washer itself is the same as that explained under Method 1. The final desired conditions are secured by adjusting the amount of preheating to give the required wet-bulb temperature at en trance to the washer. Method 3. Even if heat is added to the spray water, the mixing occur ring in the washer itself may still be regarded as adiabatic. The state Spray Apparatus 745 point of the mixture'should move'in a direction determined by4he specific j enthalpy? of the heated spray as explained in Chapter 3. /Tf ~is possible,; by: elevating the water ^temperature, to /raise the air temperature; both< dry-bulb and wet-bulb, above the dry-bull) temperature, of'the enterihg aif.i Jii each of the methods, "1, 2/or 3, the airfeaving the ;air_ washer may i require reheating to produce iq the . conditioned spacej thqirequise& 4ry-; bulb temperature and relative humidity! `'7''/'' DEHUMIDIFICATION AND COOLING WITH AIR WASHERS : V. Cooling of the wef-bulb temperature of an air vapor'mixture, ca'n be: -accomplished by an air washer if the temperature of the spray water is ; lower than, the wet-bulb temperature' of the air. ' Moisture removal is .; obtained when the spray- water , temperature-is lower than the dew-point- of the entering air. In these cases the final dry-bulb temperature and? relative humidity of the leaving air are dependent upon the design'factors ; of the air washer. - -- .. r tj--: ,\i Both sensible and latent heat are removed in the process of 'dehumidi fication by cold spray water. Abstraction of sensible heat occurs during J the entire time that the air is iri contact with the spray medium. Latent;, heat removal takes-place as condensation occurs. Therefore, .the lower the spray temperature, the greater the amount of moisture removal per" pound of dry air, all other, conditions.remaining the same.. .. Washers with two or. more banks of spray are usually selected for de- .humidifying installations, whether for comfort or industrial installations. - Generally spch air washers cool the air, to within one or two degrees (Fahren- ? heit) of the leaying spray water temperature; this differential will increase ! somewhat when the difference between the entering wet-bulb and.leaving; dew-point is relatively large. - ; Where a limited supply of cold .water is available, multiple stageiwashers: may be used to great advantage'. In such-washers the cool water is pumped through the multiple-spray systems in series and counterflow to?the air ; flow. Such an arrangement brings the delivery air-in contact with the ` coldest water, securing a ipaximum amount of cooling and saving water. ; . When using cold well water or water from city water mains, care should be used to secure accurate data on the water temperatures. Table 1 lists, some-approximate wafer.main averages which may be used as a guide, but? -they should be Verified from! local records. This is particularly true with -; city,water main temperatures. In the case of well water temperatures, Fig.-3 shows the apprpximate temperatures of water to be expected from wells at depths of 30 to 6() ft. . ---... ' :. Air washers for dehuinidifying and cooling usually have separate recircu lating pumps. These pumps deliver a mixture of cold and recirculated:; water under the control of a three-way valve. The valve may be actuated either by a thermostat in the-washer outlet, or by a humidity or other com trailer in the space being conditioned.' Air washers for dehumidifying are very often furnished with direct expansion or water cooling coils within the washer space, in which case water for the washer sprays is entirely recirculated. APPARATUS FOR DIRECT HUMIDIFICATION Humidifiers may be divided into two general types which are, according to the method of, operation: (1) indirect, such as the air washer, which