The University of Texas Publication No. 4811: June 1, 1948 ICE AIR CONDITIONING FOR INTERMITTENT SERVICE By WILLIS R. WOOLRICH Dean of the College of Engineering Director, Bureau of Engineering Research and FRANCIS G. WINTERS Engineering Research Assistant and JAMES D. McFARLAND Project Supervisor Bureau of Engineering Research Engineering Research Series No. 42 Bureau of Engineering Research PUBLISHED BY THE UNIVERSITY OF TEXAS AUSTIN Publications of The University of Texaa PUBLICATIONS COMMITTEE E. J. MATHEWS A. MOFFIT C. F. ARROWOOD E. S. REDFORD C. D.LEAKE W. P. WEBB A. C. WRIGHT Administrative Publications E. J. MATHEWS F. L. Cox R. C. ANDERSON J. A. FOCHT L. L. CLICK B. GONZALES The University publishes bulletins twice a month, so numbered that the first two digits of the number show the year of issue and the last two the position in the yearly series. (For example, No. 4801 is the first publication of the year 1948.) These bulletins comprise the official publica­tions of the University, publications on humanistic and scientific subjects, and bulletins issued from time to time by various divisions of the University. The following bureaus and divisions distribute publications issued by them; communications concerning publications in these fields should be addressed to The University of Texas, Austin, Texas, care of the bureau or division issuing the publication: Bureau of Business Research, Bureau of Economic Geology, Bureau of Engineering Research, Bu­reau of Industrial Chemistry, Bureau of Public School Service, and Division of Extension. Communications con­cerning all other publications of the University should be addressed to Univeri:iity Publications, The University of Texas, Austin. Additional copies of this publication may be procured from the Bureau of Engineering Research, The University of Texas Austin 12, Texas THE UNIVERSITY OF TEXAS PRESS ~ The University of Texas Publication No. 4811: June 1, 1948 ICE AIR CONDITIONING FOR INTERMITTENT SERVICE By WILLIS R. WOOLRICH Dean ol the College of Engineering Director, Bureau of Engineering Research and FRANCIS G. WINTERS Engineering Research Assistant and JAMES D. McFARLAND Project Supervisor Bureau of Engineering Research Engineering Research Series No. 42 Bureau of Engineering Research PUBLISHED BY THE UNIVERSITY TWICE A MONTH. ENTERED AS SECOND· CLASS MATTER ON MARCH 12, 1913, AT THE POST OFFICE AT AUSTIN, TEXAS, UNDER THE ACT OF AUGUST 24, 1912 The benefits of education and oj useful knowledge, generally diffused through a community, are essential to the preservation of a free govern­ment. Sam Houston Cu~tivated mind is the guardian genius of Democracy, and while guided and controlled by virtue, the noblest attribute of man. It is the only dictator that freemen acknowledge, and the only security which freemen desire. Mirabeau B. Lamar C OPY RIGHT, 1948 BY THE SOARD OF REGENTS OF THE UNIV"ERSITY OF TEX AS THE UNIVERSITY OF TEXAS BUREAU OF ENGINEERING RESEARCH STAFF T. S. Painter_____________________________________ ___________________________________________________________ President W. R. Woolrich *_ _____________ ______ Director and Dean of the College of Engineering Raymond F. Dawson_________________ _______ ___ ______________ __ _________ ____ ___ ___ ______ __Acting Director B. E. Short________________ ____ __ __ __________________ Acting Dean of the College of Engineering V. L. Doughtie_________________ _____ ______________________________ ______________ Mechanical Engineering G. H. Fancher______ __ ______________________________________ ___ ________ ___ __ __ __Petroleum Engineering A. W. Straiton......----------------------------------------------------------------Electrical Engineeirng Hugo Leipziger-Pierce___________________________________________________ ______________________Architecture Kenneth A. Kobe____________________________ ___ ______ _________ __ _____ ____ ________ Chemical Engineering M. J. Thompson_____________________________________________________ ,________ Aeronautical Engineering Leland L. Antes·------·------------------------------------------------------------Microscopy Specialist J. Pollard____________ ___ ____________ __ _______ _ ______________________ _ ___ ______ Architectural Engineering J. D. McFarland................ __________________________________________________________Project Supervisor H. E. Staph.___________ ___ _________ ______________ ________ _____________ Mechanical Research Engineer •on leave to April 15, 1949. Contents PAGE I. Preface and Introduction General -------------------------------------------·--····---·----··--·-----------·-----------------------------------------------------7 Object of Investigation -------------------------------------------------------------------------------------------------------7 II. Commercial Examples of Successful Ice Air Conditioning for Intermittent Service Highland Park Presbyterian Church of Dallas, Texas and First Presbyterian Church of New Orleans, Louisiana ___ --------------------------------------------------------------------------7 III. Considerations in the Design of Ice Air Conditioning Systems General _____ _ --9 Economy -------------·----------·-----------------·-----·--------·--·----------------------------------------------------------9 Adaptability -------------------------·------------------------------------------11 Flexibility __ .___________. ________________________------------------------___--------_____________ .___----------------11 Simplicity ----------------------------------------------------------------------------------------------------------------------------11 Ice Bunkers -------------------------------------------------------------------------------------------------------------·--------------11 (Types, Location, Design, Size and Capacity) IV. Computing the Cooling Load Estimating Data -------------------------------------------------------------------------------· -------------16 Composition of Cooling Load ---------------------------------------------------------------------------------------·---16 Body Sensible and Latent Heat ------------------------------------------------------------------------------------18 Heat of Motors, Lighting Appliances, Cooking Devices, Refrigerator Con­densers, Hot Water pipes, Etc. --------------------------------------------------------------------------------18 Heat Conducted Through the Walls ----------------------·-----------------------------------------------------19 Example of Calculating the Cooling Load ------------------------------·--------------------------------------19 V. Estimating the Cost of an Ice Cooling System General -----------------------------------------------------------------------------------------------------------------------__ ____ 22 Ice Bunkers -----------------------------------------------·--------------·----------------------------------------------------------22 Spray Chambers or Air Washers __----------------·------------------------------------------------------------------22 Fans -------------------------------------------------------------------·--------------------------------------------------------------------22 Motors ---------------··----· --·----------------------------------------------------------------------------------------------------------22 Pumps ---------------------------------------------------------------------------------------:·---------·---------------------------------25 Spray Nozzles ------------------------------------------------------------------------------------------------------------------·-----25 Ducts _____ ___ ---------------------------------------------------------------------------------------------------------------26 VI. Experimental Data on Ice Melting Ice Melting in "Still" Room Air ---------------------------------------------------------·----------------·----------27 Ice Melting in Moving Air at Different Relative Humidities ------------------------------------28 VII. Experimental Data on Ice Air Conditioning at The University of Texas Installation --------·----------------------------------------------------------·---------·--------------------------29 Performance ----------------------------------------------------------------------------------------------------------------32 VIII. Bibliography Summary of Trends Revealed in the Bibliography.. -----------------------------------------------------37 Flexibility, Simplicity of Design, Reliability of Operation, Low Installation Cost, Cost of Operation as Compared with other Methods Bibliography and Abstracts of Articles Containing Information on the Subject "The Use of Ice in Air Conditioning" ---------------------------·------------------------------39 Other Sources of Information. ---------------------------·-----------------------------·----·---------56 Illustrations FIGURE PAGE 1. Highland Park Presbyterian Church, Dallas, Texas and First Presbyterian Church. New Orleans, La. ................................................................................................................ 8 2. Cooling system using ice and water cooling tower combined .......................................... 10 3. Details of an ice bunker recommended by the American Ice Company ........................ 12 4. Arrangement of piping for ice bunker ................................................................................ 13 5. Drawings and data on Standard 'Williamson ice vaults for ice refrigeration systems .... 17 6. Graph showing approximate cost of spray chambers .............. ......................................... 23 7. Graph showing approximate cost of fans ............................................................................. 23 8. Graph showing approximate cost of induction motors ............. ................ 24 9. Graph showing approximate size of motors for driving fans .............. . 24 · ··············· 10. Graph showing approximate cost of centrifugal pumps with motors. ················ ·· 25 11. Curves showing heat transfer rate for ice melting in "still" air .... .. 26 12. Curves showing Btu per Hr. per Sq. Ft. per ° F. difference in temperature, under various degrees of humidity.............................................................................................. 27 13. Curves showing air velocity and ice meltage ...................................................................... 28 14. Plan and elevation of Room 138, Engineering Building, The University of Texas ...... 2'.J 15. Design details of ice bunker at The University of Texas.................................................. 30 16. Ice bunker at The University of Texas............................................................................... 31 17. Piping and control methods for ice air conditioning installation at The University of Texas ······························································'································································· 32 18. Dry bulb temperatures for The University of Texas installation.................................... 33 19. Dry bulb temperatures of spray chamber. The University of Texas installation ........ 3i 20. How the ice melts in the ice bunker when using sprays. The University of Texas installation . . . .. . . . . ... . . ..... .... .. . . ... ........ . ... .. . . . . . . . .. ... . . . . ... . . . .............. ... . . . . . .... ............. ............... . . .. 34 21. Specific humidities in test room and duct. The University of Texas installation ........ 35 22. Percentage humidities. The University of Texas installation............. ............................ 35 23. Average ice consumption for the test runs. The University of Texas installation ........ 36 24. Average values for The University of Texas test.................... ........................................... 37 Ice Air Conditioning for Intermittent Service I. PREFACE AND INTRODUCTION General The postwar demand for air conditioning has mushroomed into a market greatly in excess of present manufacturing capacity and supply, and far exceeds even the most optimistic estimates made prior to the war's end. This demand has opened a lucrative field in the small home and business market. Everyone, especially those in southern climates, desires the relaxing com­ fort of cool air whether at home or at work. People in times past have employed every conceivable means of keeping themselves cool, including cooling air by the evaporation of water, refrigerating air by mechanical, absorption, steam jet and gas systems, and by chilling air by one of the systems of ice air conditioning. Although ice systems were one of the first to be used successfully, there are very few installations using ice today as compared to other methods of comfort cooling. Object of Investigation The scarcity of literature on ice air conditioning seems to indicate that less studied thought has been given to air cooling by ice than by most of the competitive methods. This lack of information has prompted the Southwestern Ice Manufacturers' Association to sponsor a program of research at The Uni­versity of Texas under the direction of the Department of Mechanical Engi­neering and the Bureau of Engineering Research for the purpose of determining the characteristics, suitability, and economy of employing ice as a refrigerant in air conditioning installations, especially in intermittently occupied rooms such as auditoriums, churches, and lecture halls. The progress and current results of this investigation are the subject of this bulletin. II. COMMERCIAL EXAMPLES OF SUCCESSFUL ICE AIR CONDITION­ING FOR INTERMITTENT SERVICE Two examples of successfully operating ice air conditioners are those in­stalled in the Highland Park Presbyterian Church in Dallas, and the First Presbyterian Church in New Orleans. See Figure 1. The Highland Park sys­tem was installed in 1939 at a total cost for heating and cooling of $17 ,158, of which approximately $9,000 was chargeable to cooling. The ·church has a seating capacity of 1,200 and a calculated cooling load of approximately .90 tons at maximum peak conditions. It consists of an ice tank of the sub­merged type, an open air washer, a pump circulating water between the tank and washer, and an air distribution system with inlets through the ceiling to the occupied area. Temperature regulation is obtained through operation of a dew point thermostat in the air leaving the washer and con­trolling a three-way valve on the suction side of the pump. A room thermo­stat controls the face and bypass dampers at the washer. The maximum ice Highland Park Presbyterian Church, Dallas, Texas. First Presbyterian Church, Ne\\ Orleans, La. FIG. 1. lee Air Conditioning for Intermittent Service consumption in any one day was 14.4 tons on July 15, 1944, and the maxi­mum season consumption was 182 tons in 1944. Ice was delivered to the system at $4 per ton. The New Orleans church seats approximately 450 people and the cooling load has been estimated at 43 tons. The system consumes about 5 tons of ice per week at a cost of $5 per ton. The connected power load aggregates 8 HP and the monthly power cost has been estimated at $4.50, making the total operating cost about $104.50 per month. The system consists of a spray type ice bunker, cooling coils, pump, and the necessary fans and ducts. The installed cost has been estimated at less than one-third the investment in a mechanical refrigeration system. At present, there are several churches in Texas considering the use of ice for their cooling requirements. III. CONSIDERATIONS IN THE DESIGN OF ICE AIR CONDITIONING General The same engineering skill is required in the design of an ice air condition­ing system as is required in the design of other cooling systems. The same quantity and distribution of air are necessary, and similar air washers or cooling coils are required. The difference in design appears in the selection of the refrigerating plant itself, i.e., the method by which the spray water or cooling coil liquid is chilled. Primary considerations in the design of the plant should be economy, adaptability to existing conditions, flexibility, and simplicity of mechanism. Economy Some sections of the Southwest have an abundant supply of cool spring or well water available at a relatively low cost. In many cases this water would give satisfactory cooling results when circulated through the cooling coils or spray chamber of an air conditioning system. For unusual cooling loads this type of installation could be supplemented by further cooling of the water by ice. Where such a supply of low cost cool \Vater is not available, it may be possible to use a cooling tower to advantage. For sections of the country where there is a fairly large spread between wet and dry bulb temperatures, a properly designed cooling tower will lower the water temperature to within two or three degrees of the wet bulb temperature. In a considerable area of the Southwest this temperature difference is large enough over a major por­ tion of the summer season to justify the use of the cooling tower, and its use in such areas would result in an appreciable saving when compared with many other cooling systems. The cooling tower principle can be used in conjunction with ice for providing colder water for periods of heavy cooling load or when the humidity is high. Such an installation is shown in Figure 2. Air cooling systems installed in the immediate Gulf Coast region would need the use of ice for a greater portion of the summer .because of the higher humidity conditions which make cooling towers less effective. -0 ., = :.a s 0 u .,... ~ .s bll .s Cl 0 u '"O = al ., -~ bll ·;;= ::s t; :>-, -1 ("') (!) (!) >-1 (f) :=:i (!) s: ~ 0 ("') ~ (!) Pl 0 ..+ ~ Pl Pl (f) °"' ....... Cj <':To.. s· s (!) ("') Pl ::r" >-1 So So ~ (!) (!) (!) 0 Pl ....... :i:.. "d 0 (!) Pl ~ °"' ~·· Pl s., >-1 0... .-.. .-.. (!) ( ) (j 0 0... >1 0 ("')C"',_..g. ~ ..... § <-< o s· ...... (f) o,..C"'OQ o· q"t;(!)C"' ;::i s:s("')<-< ~· ~ "d g ..... Pl s· t:D' /6 'O' ~ aq °"' ..... ..... °"' ,...+ • (f) ...... s· g-~ s ;::i ~ ..... ::r" (!) ~ e?.. /6 ~ s ....... (!) "d ..... ..., s· < s ~ :::::: ::r" Pl '-' Pl ...... ..+ ""-. Cj >-1 (f) ,...+ ~ 0 .... Pl ::r" ~ s >-1 (!) (!) ....... Pl (!) s: ~ er ,... (f) <:::: (!) °"' 0 ~ (!) g· °"' < s: 0 ~ ~ ~ ~ (!) ....... Pl ~~"-< < ,...+ ::r" ("') Pl pi(!)O..+ ~ ~ ..... ?;" 8 ~ ~ (f) ~ >-1 ~ ..:;: q g ::r" i'.:j. (t) t"'+ ~· ...... Er-ct~& OJ The University of Texas Publication insulation.2 The walls of the vat should have a minimum thickness of 8 inches, and the bottom a minimum thickness of 12 inches. The top should be covered with 4 inches of cork or the equivalent. The concrete should be reinforced with steel, and the interior should be lined with some type of waterproof. mortar grout. As the ice in the vat melts, its cooling surface decreases. It is suggested that the ice be broken up to present a greater cooling surface. This is impor­tant, for at times of sudden increase of cooling load, greater amounts of water must be circulated through the tank, and sufficient ice surface must be present to cool the water adequately to absorb the load change. Turbulence other than that supplied by natural circulation might even be necessary. Location of Bunker Regardless of whether the spray or submerged type of bunker is used, the bunker must be of rigid construction and easily accessible for cleaning and loading. The ease with which the ice is loaded is important, as a poorly located or designed bunker can increase the cost of delivered ice to a pro­hibitive amount. Design of Bunker The design of the bunker should be such that it is adaptable to all com­mercial forms of ice, i.e., crushed, broken, block and special processed. The tanks should have adjustable overflow and sewer pipe connections to retain proper water level and to insure good pump operation. Size and Capacity of Bunkers The size and capacity of the ice bunker is determined by the amount of ice consumed between loading periods. The usual loading period for daily operation is 24 hours. For small installations, the bunker capacity could be made sufficiently large to hold enough ice for two or more days' operation without recharging; depending, of course, on the space available. Most ice systems, however, are operated only a few times a week and the ice bunker is made to hold a week's supply of ice. In calculating the amount of ice that will be consumed between loadings, any one of several methods may be used. Some authorities state that the usual hourly ice consumption can be expected to average between 50 and 60 per cent of the estimated maximum ice meltage, and gives 162 Btu per lb. as the cooling capacity of one pound of ice as a basis for determining the ice consumption for a given load.3 Considering The University of Texas installation with its estimated maximum peak cooling load of 11 tons as an 2"The Construction and Operation of Air Conditioning Systems Using Ice," by R. C. Stubbs. Ice and Refrigeration: Vol. 101 , No. 2, Aug.• 1941 , pp. 167-168. ~"Display Installation of Comfort Cooling Systems." by Judson Neff. Ice and Refrigeration: Vol. 85, No. 2, Aug., 1933; pp. 49-53. "Comfort Cooling with Use of Ice." Ice and Refrigera­ tion: Vol. 91, No. 6, Dec., 1936; pp. 437-438. Ice Air Conditioning for Intermittent Service example, and assuming that the average ice meltage will run 55 % of this figure, then the required bunker capacity using 300 lb. bars of ice is: 11 x 12,000 x 0.55 x 12 X or 17 .9, say eighteen 300-pound cakes of ice, where 300 162 twelve hours of operation per day is· to be expected. Another method expresses the required bunker capacity in terms of the Btu absorbed per degree F. temperature difference between the conditioned space and the outside as 1.33 lbs. per Btu absorbed per degree F. temperature difference; or 3Yz tons per season per 100 Btu absorbed per degree F. tempera­ ture difference.4 A third method gives the required bunker capacity as 0.165 lbs. per cu. ft. of air moved during the cooling period between loadings.5This method • gives for The University of Texas system a required bunker capacity of 2,200 X 12 X 0.165 = 4,400 pounds, or fifteen 300-pound cakes of ice where the average air circulation was 2,200 cfm. A fourth method proposed gives the required bunker capacity in 300-pound cakes by means of two formulas expressing the necessary capacity to provide adequate cooling surface, and the necessary capacity to accomplish the cool­ ing.6 The capacity in 300-pound cakes to provide sufficient cooling surface . . Btu/ Hr. (max) . . is given by , and the number of cakes to accomplish the coolmg 5 8, 00 . . b Btu/Hr. (ave) X h h h . h h f . Th is given y X w ere is t e ours o operation. e 1arger 300 162 number is the required bunker capacity. The necessary bunker capacity can also be determined by the slightly dif­ ferent method of assuming a system efficiency that can be expected. If an efficiency of, say, 88 % were assumed, then the hourly ice meltage would be 200X60 84 d h ff" . 0 2 X0.S= poun s per our per ton o re ngerabon, or .04 tons per 162 8hr. per ton. On a 24-hour basis, this would mean that a bunker capacity of 1.01 tons of ice per ton of refrigeration would be required. That is, if the · average load for the 24 hour period were 10 tons, then the ice bunker should have a capacity of 10.1 tons of ice. As to the actual physical size of the bunker necessary to contain the required amount of ice, one engineer recommends 14 square feet of bunker area for 7 each ton of ice capacity. On this basis, by the assumed efficiency method the bunker should have an area of 14 X 1.01 = 14.14 sq. ft. per ton of refrigeration 4"Space Cooling with Ice," by C. D. Robison. lee and Refrigeration: Vol. 77, No. 5, Nov., 1929, pp. 305-308. 5"1ncreasing the Ice Business by Developing Space Cooling," by M. D. Leslie and J. W. Ankenman. lee and Refrigeration: Vol. 81, No. 3, Sept., 1931, pp. 133-136. 6"Comfort Cooling with Use of Ice." lee and Refrigeration, Vol. 91, No. 6, Dec., 1936, pp. 437-438. 7"Construction of Ice Bunkers for Comfort Cooling." Power Plant Engineering: Vol. 38, No. 10, Oct., 1934, p. 478. The University of Texas Publication per 24-hour period. The minimum depth which has been employed or recom­mended from time to time has usually been 7% feet, which, in round figures, would mean a bunker volume of 8 X 14.14 or 113 cubic feet per ton of refrigera­tion per 24-hour period. It is apparent that the above methods as outlined will give divergent results for the same set of cooling conditions and requirements. Only one source has been found which gives recommended bunker dimensions together with the capacity obtained.8 This is presented in Figure 5. Perhaps the most convenient method of determining the actual bunker size would be to obtain the required ice capacity by means of the two formulas expressing the number of 300-pound cakes required for sufficient cooling surface and sufficient cooling capacity, and then to refer to Figure 5 for the corresponding bunker dimensions. Little information on the actual physical size necessary for the concrete vat type of ice bunker is available or has been published in the literature. How­ever, the ice vats in most of the installations are built 8 feet deep and a 6-foot maximum water depth is maintained. On this basis, the volume per ton of ice capacity determined above for the spray type bunker should also apply here. IV. COMPUTING THE COOLING LOAD Estimating Data Some estimating data for computing the cooling load are: (a) For most church buildings the approximate refrigeration tonnage can be estimated by dividing the total seating capacity of the space to be cooled by 16. (b) Approximately one-half of the tonnage will be the heat load of people, one quarter of the load will be the heat load of necessary replacement fresh air, and the other quarter will be due to radiation and appliances requirements. ( c) One ton of ice can be expected to give 1.2 tons of refrigeration. Composition of Cooling Load The cooling load of a room is made up of: (a) Body sensible and latent heat of the animal and human occupants within the room to be cooled. (b) Heat of the motors, lighting appliances, cooking devices, refrigerator condenser, hot water pipes. and similar equipment from which the heat is discharged into the room. ( c) Heat conducted through the ·walls from the outside air caused by the lower temperature on the inside. (d) Heat of the sun's rays and radiation through exposed windows, sky­lights, and walls. ( e) Heat of tlw ''make-up" and the infiltration .air entering the room. '"Comfort Coolinµ with Ust> of ke." lee and Refrigeration: Vol. 91 , No. 5, Nov., 1936, pp. 359-361. 0-Q;' 8 g, '--~ "d ~ ::;.­ (!) ~­ ,..._ ::l 0 (!) o"' @ (!) CJ> CJ> (") Q.l 0 ,, ~~ ~ 0 .§~ Oro ;J ,, ~s­ Q.l (!) ;:;_ ,... ..... (!) ::l !:"1 l)q P "Oro s::,, "OQ.l ,... 8' ::r" '"'! ro ro B I I A =----1 ~,,.. ,,,,:· T "·''.:.-...~....;....;·::-::; E o-­ J I 0 :;: u. ':~ METAL LINING + l ;·. ·. ­ ;': NOT INCLUDED ·:; '. . .. .,' ... .··' .T.; '. ; '.· = ·• ';~J '.; :'. ;!'~;] LONGITUDINAL SECTION TRANSVERSE SECTION ' PLAN ELEVATION VAULTS 1, ,2, 3. I ~­ be selected. Also, before the motor can be selected the duct layout should be checked to see that the static pressure does not exceed the static pressure shown in the curve. Pumps The spray water, both for the ice sprays and the air washer, should be handled by motor driven centrifugal pumps. Units in which the pump and motor are connected are preferred for this type of work. The average cost for such pump units is indicated in Figure 10. 240 --i..--~ 220 200 i..---­ i.--­ ISO v....­ __,,.. ~ 160 ~ /'/"' '.J · 140 v ~ 120 ~ COST OF PUMPS ~ 100 WITH MOTORS ..... 1948 -­ E ao v 60 40 20 00 10 20 .30 ·40 50 60 70 80 /00 CAPACITY /N GALLONS PeR M/Nt/TE A6A/N.ST 25 FT· HEAO FIG. 10. Graph showing approximate cost of centrifugal pumps with motors. Spray Nozzles For estimating purposes the cost of the sprays may be taken as approximately $1.50 each. Spray nozzles manufactured by one supplier are priced currently from $1 to $11.25 and have capacities ranging from 0.141 GPM to 175 GPM. The nozzles most commonly used in air conditioning work cost less than $1.50. Atomizing nozzles are available in capacities from 2.3 GPH to 5.8 GPH at a cost of $1.20 each. The spray nozzles used in the spray chamber and the ice bunker of The University of Texas installation, cost approximately $0.40 each. For many installations ordinary lawn sprays can be used. These have given satisfactory results and are easily obtainable at a cost of about $0. 75 each. Ducts Factors to be considered in estimating the cost of duct work are: Volume and velocity of air to be handled. Whether ducts are round or rectangular. Whether ducts are exposed or unexposed. Number of branches, transitions, and elbows involved. Availability of materials. Cost of labor. Duct work is sold by the fabricator by weight. The average cost varies from $0.84 per pound for installations up to 1,500 pounds, to $0.62 per pound for those 1,500-25,000 pounds. In estimating the weight the following U. S. Standard gauges of galvanized iron pipe must be considered: 4.5~~-,....-~..----r'---r-~--.-~-.-~.------.-~~~~ . 50 60 70 . 80 !JO KJO WET BVLB TEMPERATURE -J;,8 (~/i) ' Round ducts less than 20 inches in diameter are usually 26 gauge; from 20-29 inches, 24 gauge; from 30-39 inches, 22 gauge; from 40-49 inches, 20 gauge; above 49 inches, 18 gauge. Rectangular ducts less than 18 inches wide are usually 26 gauge; from 19-30 inches, 24 gauge; from 31-60 inches, 22 gauge; from 61-118 inches, 20 gauge; above 118 inches wide, 18 gauge. VI. EXPERIMENTAL DATA ON ICE MELTING Ice Melting in "Still" Room Air Numerous inquiries have been received requesting information on the effectiveness of cooling a room by placing a cake of ice in the space to be cooled. During 1938 and 1939, the Mechanical Engineering Department and the Bureau of Engineering Research at The University of Texas conducted tests on the melting rate of ice in normal "still" air.9 In the typical room this presents a space convection air velocity of 15 to 25 feet per minute. The results of these research studies expressed in the heat transfer rate per hour per square foot per °F. is given in Figure 11 . AIR VELOCITY//'( reET PER MINOT/: FIG. 12. Curves showing Btu per Hr. per Sq. Ft. per ° F. difference in temperature, under various degrees of humidity. 9"Jce Melting and Freezing Rates," by A. H. Willis, B. E. Short, and W. R. Woolrich, Refrigerating Engineering: Vol. 39, May, 1940, pp. 307-310. As an example in interpreting these curves a room that had a wet bulb temperature of 80° F. and a dry bulb of 90° F. would have a heat transfer rate per square foot of exposed ice block surface per hour per Fahrenheit degree temperature difference of 2.8 Btu. This is not a very effective cooling procedure. Ice Melting in Moving Air at Different Relative Humidities P. W. Scates10 made a study of the rate of ice melting in moving air at different velocities and at different humidities at the Engineering Experiment Station at the University of Tennessee. Figures 12 and 13 show some of the results graphically expressed that were obtained in that study. Ice melts much more rapidly under conditions of high humidity and high air velocity and thus under these conditions does a more effective cooling job. 0 Fm. 13. 20 40 60 80 PER C&:NT HUMIDITY Curves showing air velocity and ice meltage. 100 10"The Rate of Ice Melting," by Paul "VV. Scates, Refrigerating Engineering: Vol. 22, .July, 1931, pp. 15-17. VII. EXPERIMENTAL DATA ON ICE AIR CONDITIONING AT THE UNIVERSITY OF TEXAS Installation In order to obtain data and a working knowledge of the present-day costs of ice air conditioning, the design, construction, and installation of an ice system at the University was undertaken. An ice system was installed to cool Room 138 in the Eigineering Building, the plan and elevation of which are shown in Figure 14. This is a small auditorium room seating approximately 125 people, and with a volume of 14,100 cubic feet. A mechanical air condi­tioning system was already installed and, consequently, use was made of the spray chamber, fan and duct work previously installed. NORTH WALL: FRAME -l"X a• SHIPLAP ON 2• X 4• STUDDING WEST WALL EAST WALL: e• SAME AS HOLLOW TILE NORTH WAL L PLASTERED BOTH SIDES FIG. 14. Plan and elevation of Room 138, Engineering Building, The University of Texas. A spray type of bunker was used in preference to the vat type of ice tank because of the superior ease with which a spray bunker could be erected in space adjacent to the room and convenient to the air washer. In addition, the literature had from time to time recommended the spray type bunker over the ice tank. r "' '-..., ,t -'b ' I ~ ,.,.._ ~1 0 .,!, ;., :Tl:i! I .L I io 0 I t I­ -.'..~ t z ~I "' ;., ..__ WCI> I:::! WO.. --:r t~ a: ­ 0 ::c 01 ;., C/) 0 b :cw ;jl J: C/) 0 .., w- i:;I 2 .:l_~ ::c . -'I 1: ... u ;~­ a: .... +-I "'':'::;: i~ l::l ==,;:I ,.6·,• i? ..."'1 b f~ C/) 0 ;., z 0 ­ -.!.. i~ ti "' ........ :; C/) t> ..... iii "'o ':'~ 0 N z-. J .., o::c '• 2i l x =>1­ I'"' 1-­ N 'Cl))i: !~ ~l lH l:;" Ht "il I x I > 0 0 ..J m io x ;,. x .... ~...., a:<> o"' o..a: 0.. ijl~ ..o•-.9 J .., "' z .... "' C/) Ci "., a: a: 0 ... x ... :::> ..0.. .... .... C/) 0.. z" z "'o en=.:,. ·-"" .., .. al ,_ x a: .... "' z (I) Cl : ;, 1.f(/)a: "' .. "' :;: ;: ;., ... .. .., ...-~ ::c ..J zu C/) o­:::>Oo "'C/) ........ 0 ~~ 0 w.., z 0 :; 3: 5~ :co.. C/) ... ..J . C1I '., x ii 2 _, The installed ice bunker occupies a space approximately 4' x 8' x 6' high and has a capacity of 4,800 pounds of ice. It is an adaptation of a design published in the literature and presented in Figure 15. It is constructed of wood and the interior is water-proofed by means of galvanized iron sheathing. In­sulation is obtained by filling the sides and top with granulated cork deposited between the 2 x 4 studding. Insulating paper is employed under the outside wood siding as an air seal. The exterior appearance can be seen in Figure 16. FIG. 16. Ire bunker at The U niwrsity ofTexas. The water is distributed over the ice by means of 24 type 1x431 nozzles spaced on 9 x 15-inch centers. This arrangement provides 6 rows of nozzles with 4 nozzles to the row. Figure 17 shows the arrangement of the system. EQUALIZING LINE BETWEEN ICE . BUNKER AND AIR WASHER ICE BUNKER AIR WASHER FIG. 17. Piping and control methods for ice air conditioning installation at The University of Texas. Performance The performance of the system is presented as a series of graphs and tables which give the temperatures, humidities, and other values, compiled in the form of a mean run. This so-called "mean run" is the performance that can be expected on an average day under average conditions. The results are actually a compilation of the data obtained from 8 different runs which were made during the period from July 25 to August 21, 1947. These runs were made under very divergent conditions. Some were made on very hot and dry days, others on rainy days. In some, no human load was present, in others the human load varied considerably. In general, weather conditions were milder than average, and the summer classes were small, such that peak load conditions were not encountered. Figures 18 to 24 present the air and water temperatures involved, and other data obtained on the operation of the system. Figure 18 presents the dry bulb temperatures that could be expected during the operation of the system, and Figure 19 presents the performance of the spray chamber. As the air passes through the air washer, a temperature drop of approximately 13° F. is obtained. The spray water temperature drops for the first 2 or 3 hours of operation, then slowly rises. This is due to the melting of the ice in such a manner that as time goes by, an increasing amount of water sprayed over the ice fails to hit ice surface and falls to the bottom of the bunker without being cooled. Figure 20 is an illustration of how the ice melts down to stalagmitic formations. This erosion effect could be reduced by partially atomizing the spray water. Results of experiments reported in the literature support this contention.1 1 110 60 8:00 /():()() /2:0tJ 2:00 4:oo 6:00 A.M. p. M. TIME OF .OAY Fw. 18. Dry bulb temperatures for The University of Texas installation. Figure 21 shows the variation of the specific humidity in the duct and in the room, and Figure 22 presents the percentage humidities present in the sys­tem. The seemingly high humidity in the room is not due to the fact that ice was used as the refrigerant, but rather is due to poor spray chamber per­formance. The supply air was not cooled sufficiently before being sent to the room. ''"Research Data and Applications of Ice to Air Conditioning." hy B. S. Williams. Ice and Refrigeration: Vol. 83, No. 2, Aug., 1932, pp. 49-53. e:oo 10:00 /2:00 2:00 4:00 6:00 A.M. P.M. TIME OF DAY .­ FIG. 19. Dry bulb temperatures of spray chamber. The University of Texas mstallation. FIG. ZO. How the ice melts in the ice bunker when using sprays. The University of Texas installation. .O/G .oo 4:00 6:00 8:00 P.M. FIG. 21. Specific humidities in test room and duct. The University of Texas installation. 100 I ' Duct Humid/I>:; - Roon? .Hurnla'lly) _ ­-..... ....... - "'\.. ' ...... - -/our..slde llum/dlly ......... tJ . _,,,,.. ............. MEAN RUN HUMIDITIES I I I I I 0 B:oo /P:oo 12:00 2:00 4:00 6:00 A.M. P.M. TIME OF OAY F1G. 22. Percentage humidities. ThP University of Texas installation. Figure 23 shows the average ice consumption for the various runs and Figure 24 presents averages of the various data obtained such as load, ice consumption, and volume of air circulated. The efficiency seems rather low, but if the overflow were dumped to the sewer at 60° F. and pipe insulation employed. the efficiency would approach 88 % . ICE CONSUMPTION, TONS PER 24HR.S. Pel? TON OF REFR/6ERAT/t:JN LOAO - I I I I I I I ·I TONS ICE MELTED PER HOOR ;;; PER TON OF REFRIGERATIONUlllD l'-'> . '.>.> ~ ~ ~ ~ I it > < ct> .., l1Q"' '"' ' ;:;· ct> B = s: "' s ~ ~ 5· = );) -. 0 .., ;. ~ '"' ... ct> ~ ::! :; ~ ~ "' ~ ~ ct> =­ Cl'I e t"1 \rw = <" ~· ct> .., q ~. S, 0\ ~ ;.: "' 0: "' ..."' = ~ "' E" §" Q) Ice Air Conditioning for Intermittent Service AVERAGE VALUES OBTAINED 1. Load in tons of refrigeration.................................. 3.17 tons 2. Ice consumption in pounds per hour.___________________ 323#/hr 3. Ice consumption in pounds per hour per ton of refrigeration ---------------·--·-·····--······················--··· 102#/hr/ton 4. Ice consumption in tons per hour per ton of refrigeration ················-··--·-·------··---·-··-----·---------0.051 tons/ hr/ ton 5. Efficiency* -------·--···---··---------····---··-·----·················-·· 68.5% 6. Relative humidity in room.......... ______________________ ___ _ I 65% 7. Temperature differential obtained....................... Max. 17.5° F. Min. 10° F. 8. Cubic feet of air circulated per minute................ 2,200 cfm !1 I Ii 9. Gallons of water circulated per minute______________ 4.5 gpm 10. Ice box pump discharge pressure_ _________________ ____ ____ 42 psig 11. Spray chamber pump discharge pressure............ 35 psig 12. Barometric pressure·---------------·-·-----··--·-·-··-······-----·-29.43" Hg. *It is assumed that the ice melts to water at 60° F. Therefore, one pound of ice absorbs 144 Btu (heat of fusion at 32° F.), plus· 28 Btu (heating from 32° F. to 60° F.) zoo . or 172 Btu/lb. An efficiency of 100% would be melting -= 1.163 lbs/min/ton of 172 refrigeration = 69.8 lbs/ hr/ ton. An ice consumption of 102 lbs/ hr/ ton would repre­ 69.8 sent an efficiency of --= 68.5%. 102 Fm. 24. Average values for The University of Texas test. At present, the system consumes its load of ice in two days' operation, which represents a daily ice cost of $4.80 on the basis of $4 per ton delivered. The only other operating expenses involved are the power charges for operating the % HP fan, and the 11/,i. HP total of the two pumps, a total of 2 HP connected. VIII. BIBLIOGRAPHY Summary of Trends Revealed in the Bibliography The completed bibliography consists of abstracts and sources of articles which have been published in American technical literature over the past two decades and indexed in The Engineering Index or the Industrial Arts Index. The Uni/Jersity of Texas Publication In reading and preparing this bibliography, it has been interesting to note that the idea of using ice for air conditioning and space cooling has developed from the beginning of the time when attention was turned to the subject of air conditioning. If the amount of published material on the subject is used as a guide, then it can safely be said that the greatest number of ice installa­tions and thinking on the use of ice took place in the ten-year period prior to 1937, and especially before 1934. Little thinking and few installations were made after 1937. The second world war definitely reduced the installation of new air conditioning systems of the ice cooling type. The increased demand for ice for both domestic and army use, together with the difficulties expe­rienced in securing repairs and equipment, were largely responsible for this sudden interruption of commercial interest in the expansion of ice cooling. Ice systems have been employed in a wide variety of installations and with wide divergence of loads and cooling conditions. They have been installed in banks, restaurants, railroad cars, theaters, homes, office buildings, club rooms, lodges, churches, and a wide variety of other places. This divergence. of applications has demonstrated and emphasized the several advantages and disadvantages of using ice. The ice cooling advantage frequently given first mention is the extreme flexibility of the systems to meet variable cooling loads. The design of most air conditioning systems involves the installation of a refrigerating plant having a capacity sufficient to handle the maximum peak cooling requirement. In the case of a mechanical system, this results in excess capacity at low loads. In the case of ice, the temperature remains constant, and the amount of re­frigeration is varied by melting more or less ice with no loss in efficiency. This feature shows up markedly in jobs such as restaurants, where the load between meals is only a fraction of that at meal times, and in churches, or other meeting places used only a few times per week. A second consideration that receives favorable recognition is that ice air conditioning enjoys a great advantage in the simplicity of its design. While the same amount of engineering skill and thought are required in calculating the cooling loads and in designing the equipment as for other types of air conditioners, the operation of the ice system is such that anyone possessing the ability to obtain the ice and push a button is capable of using it. The absence of expensive machinery and equipment such as compressors, con­densers, evaporators, and cooling towers, precludes the necessity of hiring a highly trained engineer to operate and maintain the plant. This simplicity of design is further reflected in the reliability of operation of the ice system. Breakdowns are quickly and easily repaired, and at small expense. Parts and materials shortages do not seriously affect an ice cooling system, and the scarcity of skilled mechanics does not preclude securing good service from an installed system. The absence of expensive machinery and equipment gives to ice cooling the distinct economic advantage of being one of the cheapest air conditioning systems to install. As was pointed out above, the initial cost of an ice system has been only a fraction of that of installing an equivalent mechanical unit. Ice Air Conditioning for Intermittent Service From the operating standpoint of view, the cost of operation will depend on the individual job. Ice air conditioners will, in most cases, cost more to operate than an equivalent mechanical system if investment charges are ignored. The principal reason for this has been the high cost of delivered ice. The determining factor as to which method will be cheaper is the hours of operation per year and the cost of ice. A high load factor favors the mechanical system, and becomes increasingly so in localities having a long cooling season. On the other hand, a low load factor and a short cooling season favor the ice system. The effect of these conditions becomes more apparent for a long cooling season of, say, 7 or 8 months' duration, where the high rates of depreciation, insurance, etc., of the mechanical system are charged off over a large number of operating hours, whereas in a short cooling season, these fixed charges become very large on a monthly basis. The results of research investigations by the Association of American Rail­roads12 and the University of Illinois Engineering Experiment Station13 have shown to some extent the relation between the operating cost of ice systems and other types of cooling. The relatively high cost of delivered ice in each case made the cost of ice air conditioning on a day to day basis higher than for other methods. For short cooling seasons of, say, not over five months' duration, the higher depreciation rate of the mechanical system exceeded the higher operating cost of the ice system, but for longer cooling seasons, the mechanical system was depreciated over a longer period and its operating cost generally became less than that for ice .. This limitation indicates that ice is most suitably adapted to installations which have a low load factor and varying cooling requirements. Ice is most economical for rooms requiring intermittent cooling service generally not in excess of 1 to 3 days per week. BIBLIOGRAPHY AND ABSTRACTS OF ARTICLES CONTAINING INFORMATION ON THE SUBJECT "THE USE OF ICE IN AIR CONDITIONING" This bibliography is based on articles· indexed in the Engineering Index and Industrial Arts Index. The publications include: Automatic Heating and Air Conditioning; Domestic Engineering; Elec­trical West; Electrical World; Heating, Piping and Air Conditioning; Ice and Refrigeration; Power; Power Plant Engineering; Iron Age; Railway Age; and Refrigerating Engineering. This bibliography is arranged alphabetically as to the name of the periodical, and then historically as to volume number and date of publication. "Ice in Air Conditioning,"by 0. W . Kothe. Automatic Heating and Air Conditioning: Vol. 11, No. 2, Aug., 1939, pp. 1617, 41-43. 12"Air Conditioning by the Railroads." Ice and Refrigeration: Vol. 92, No. 3, March, 1937, pp. 189-190; No. 6, June, 1937, pp. 421-422. 13Bulletin No. 290, Vol. 36, Jan. 1, 1937, University of Illinois Engineering Experiment Station. The University of Texas Publication Discussion on use of ice as cooling medium in air conditioning work. Discus'Ses: 1. Application to offices-adaptable to cooling by portable unit coolers holding 25-300# ice. Data to determine amount of heat absorbed by ice. 2. Insulated piping-recommends all piping be insulated by 1" cork or equivalent. ( 1" hair felt, strips 4" wide x 6' long wound around pipe, secured by copper wire. V\'rap with water proof canvas ducking. 3. Drain pans-supply to catch condensation under cooling coils. Spray nozzles on 10-12" centers, velocit~-of air less than 500 fpm in washer; rnpacity of sprays usually 2 gpm at 20#/ sq. in. "Ice-Design, Installation and Operation of Home Cooling Job," hy G. B. Heimrich. Domestic Engineering: Vol. 140, No. 3, Aug., 1932, pp. 43-47. Complete data and calculations on home air conditioning by the use of ice. Gives cost, sun effect, calculated load, arrangement and type of equipment, and other data. "Control Methods for Ice Melting." by R. T. Brizzolara. Domestic Engineering: Vol. 138. No. 2, Jan. 23, 1932, pp. 26-27, 107. Describes various methods to control the rate and uniformity of ice melting: 1. Use tall, narrow ice chambers: 26" x 32" x 10" using broken ice. 2. Spray system giws greater coefficient of heat transfer. Approximately 500 Btu per sq. ft. per °F. Discusses the proper insulation of ice melting tank: Interior sealed from insulation; exterior air excluded from insulation surface; exterior should be sealed against high vapor pressure infiltration, and ventilation of inside insulation to cold low vapor pressure interior will reduce condensation. Hermetical seal not best. 4" cork in 2 layers recommended. Hot asphaltum over studding. Plaster courses 1h" thick at least. "How Ice Is Used for Space Cooling," by Terry Mitchell. Domestic Engineering: Vol. 138, No. 2, Jan. 23, 1932, pp. 24-26. Lists various ice installations. Says: 1. 300# ice will cool room 12' square for 6-8 hours. 2. 215 cu. ft. per hr. per person, give off 290 units of heat. Three methods· of cooling air with ice: 1. Water piped through coils or fin type cooler. 2. Ice sits on top of plates and water runs down the plates. 3. Spray washer. "Ice Used for Cooling," by G. J. Grieshaber. Domestic Engineering: Vol. 137, No. 2, Oct. 17, 1931, pp. 40-41, 128-129. Description of two typical ice installations, one in a residence, one in an assembly room. Describes capacities of the systems. temperatures obtained, photographs. "Comfort Cooling and Air Conditioning with Ice," by A. G. Riddell. Electrical West: Vol. 70, No. 6, June, 1933, p. 243. Irregular cooling season fayors ice due to its cheapness and flexibility of delivery. Discusse~ installation and costs for Pullman cars ($2,250 new, $3,450 after car built) , and unit conditioners ($50-$250. 50-LOOO# ice per day). Discusses Detroit Edison ice installation: 57,000 cu. ft. cooled, 119.2 tons consumed July, 1932. Most cons'Uilled per day was 5 tons; cost was $6,100. "Ice for Air Conditioning," by E. C. Soares. Electrical World: Vol. 100, Oct. 29, 1932, pp. 596-597. Best for short time loads or rapidly fluctuating loads. Utility sales to ice manufacturers offers splendid load. Suggestions as to energy required. If cheap ice used in air conditioning, made for less than 50 KW-HR; melted with about 5 KW-HR. First cost of ice 25-30% of mechanical system. Ice Air Conditioning for Intermittent Service Six advantages of ice: 1. Readily available. 2. Can yield any reasonable refrigerating rate. 3. Melting rate independent of its production rate. 4. Represents the storage of transformed energy readily available at all times. 5. Constant temperature. 6. Power sold at very high load and power factor. Problem today to reduce distribution costs. "Power Sales Grow with Iced Comfort Cooling," by E. A. Brandt. Electrical World: Vol. 100, July 9, 1932, pp. 54-57. Discussion of expected growth in power consumption by ice industry due to expected in­crease in use of ice in air conditioning. Photographs of commercial portable unit coolers and central systems. "Ice Cools New Apartment Building," by E. 0. Young. Heating, Piping and Air Conditioning: Vol. 9, No. 8, Aug., 1937, pp. 484-491. Cooler installed in each apartment of an apartment house. Ice tank placed under kitchen sink. Uses 3" cube ice, approximately 200# ice per day. Installations cost approximately $150 per apartment. "Air Conditioning with Ice," by C. F. Holske. Heating, Piping and Air Conditioning: Vol. 7, No. 8, Aug., 1935, pp. 387-388. Presents consumption of ice and load factor for several installations. Wide variations in ice consumptions from year to year. Believes ice consumption varies quite regularly with volume of business. "Choosing the Right Air Conditioning System," by A. vV. Chaney. Heating, Piping and Air Conditioning: Vol. 6, No. 11, Nov.. 1934, pp. 455-459; No. 12, Dec., 1934, p. 508. No. 11. What is the proper viewpoint? Considerations to be considered in using air con­ditioning. Distinctive features of air conditioning. Difference between industrial and comfort air conditioning; how to compare systems. No. 12. Air conditioning methods, equipment, and problems presented. Discussed the objec­tives of an air conditioning system under: use of system; owner's requirements; functional and technical requirements: method of operation: mechanical considerations; physical require­ments; quietness neeystem employed to cool P. R. R. diners. Advantages of the use of ice; results of experiments on the diner; regulation of the temperature. Use of York portable air cooler with comfort conditions obtained with noise and dirt. Photos and diagrams included. "City Ice and Fuel Company Reports lncreused Use of Ice for Air Cooling." Ice and Re­frigeration: Vol. 81 , No. 4, Oct., 1931, p. 214. A look at the market for ice in air conditioning in which a larger demand for ice seen. The University of Texas Publication "American Ice Company Reports Sales of Ice Air Cooling." Ice and Refrigeration: Vol. 81, No. 4, Oct., 1931, p. 214. Statement of the sales of ice m ice air cooling. Says 1,250,000 pounds of ice used in July for ice air cooling. "Boston and Maine Railroad Uses New Method of Cooling Cars." Ice and Refrigeration: Vol. 81, No. 4, Oct., 1931, pp. 202-214. Illustrated description of refrigeration obtained from circulating water sprayed over ice carried in bunkers beneath the car. Gives method of cooling, dehumidifying, and circulating cool air. Automatic installation. See also: Refrigerating Engineering: Vol. 22, No. 4, Oct., 1931, pp. 240-244. Railway Age: Vol. 91, No. 6, Oct. 17, 1931, pp. 588-590. "Air Cooling with Ice." Ice and Refrigeration: Vol. 81, No. 4, Oct., 1931, pp. 207-211. Problems to be met in designing a system for cooling air by ice. Proper interior and effective temperatures. Methods of cooling air with ice, with figures and illustrations of each. Describes Dricool and Unicool unit air conditioners. Also lcecool unit with description. "Telling the Story About Ice Cooled Air," an editorial. Ice and Refrigeration: Vol. 81, No. 3, Sept., 1931, p. 190. An editorial stressing the need for telling the public about the use of ice for air conditioning. "The Story of Ice-Cooled Air Needs Telling," by H. F. Relig. Ice and Refrigeration: Vol. 81 , No. 3, Sept., 1931, p. 164. Article stresses the need for informing restaurant owners about successful ice installations in other restaurants, telling banks about other banks that are ice cooled, telling beauty shops about other beauty shops, etc. "York Sleeping Car Cooler," news article. Ice and Refrigeration: Vol. 81, No. 3, Sept., 1931, p. 139. Illustrated description of apparatus mounted on baggage truck. Designed to precool Pullman cars in railway station. Suggestions as to other uses for the apparatus. Can cool cars down to 75° F. with outside temperatures of 95° F. Diagram included. "Air Cooling with Ice," by F. A. Kitchen. Ice and Refrigeration: Vol. 81, No. 3, Sept., 1931, pp. 137-138. Discussion of factors to consider in the application of ice to air conditioning such as calcu­lating capacities needed, proper temperatures, and proper relative humidity to maintain. "Pennsylvania Railroad Diners to Be Cooled with Ice," news article. Ice and Refrigeration: Vol. 81, No. 3, Sept., 1931, p. 136. Very short news article describing new ice cooling system to be installed on P. R. R. diners. Consists of an ice chamber under the car. Ice water flows to radiators over which blowers force air into the car. "Increasing the Ice Business by Developing Space Cooling," hy M . C. Leslie and J. V\7. Ankenman. Ice and Refrigeration: Vol. 81, No. 3, Sept., 1931, pp. 133-136. Article discusses two installations: one which cools an office of 54,000 cubic feet volume and uses 8,000# ice daily; and second, an installation consisting of four separate units. Tables of performance data and diagrams give installation costs, ice consumed, cooling effected, and other data. "Comfort Air Conditioning with Ice," an editorial. Ice and Refrigeration: Vol. 81 , No. 2, Aug., 1931. p. 116. Article says when ice cnn be obtained at a reasonable price, it can compete with machines in small and medium purposes. Reduction in initial cost decided advantage. "Recent Developments in Comfort Cooling with Ice," hy F. I. McCandlish. Ice and Re­frigeration: Vol. 81, No. 2. Aug., 193L pp. 97-98. A discussion of the progress made in the use of ice for air conditioning in various applica­tions such as railroad passenger cars, restaurants, etc. "Comfort Cooling with Ice," by A. J. Authenreith. Ice and Refrigeration: Vol. 81, No. 2, Aug., 1931, pp. 75-76. Discusses ice air conditioning system. in Forum Cafeteria, Kansas City, Mo. System gave perfect comfort during hottest weather. Ice was only cooling medium used. Intake air blown through sprays of water kept at the proper temperature by flowing over ice; sprays remove odors, impurities, and some moisture from the air. Efficiency and reliability of the system not only recommending features. Extreme sim­plicity made possible great saving in initial investment over any oth~r system. In general, the system maintains a dry hulb temperature of 10-15 degrees F. below out­side air, and a relative humidity of 55%. "Comfort Cooling." by F. I. ?11cCandlish. Ice and Refrigeration: Vol. 81. No. 1, July, 1931, p. 24. Divides comfort cooling into two fields: domestic and commercial. Discusses a unit type cooler operated at a slow speed: tests indicate than one air change every 10-12 minutes is sufficient. This slow speed operation allows the air to be cooled over a greater range in passing through the unit. Air may therefore be cooled to dew point and excess moisture taken out and relative humidity reduced. Cooling large \·olume of air over small range tends to increase relative humidity. "Ice Air Cooling Device." Ice and Refrigeration: Vol. 81 , No. 1, July, 193L p. 16. Discussion and description of a device patented by R. H. Hardin. "Automatic House Cooling," by J. E. Bullard. Ice and Refrigeration: Vol. 81, No. 1, July. 1931, p. 1. Discussion of possibilities in providing cooling systems for small residences; various methods possible. Installation for cooling with ice ran he made on economical basis. Stresses fact that research in this field is important. "Cooling for Comfort by Melting lee," by F. I. J\1cCandlish. Ice and Refrigeration: Vol. 80, No. 6, June, 1931, p. 487. For the larger installations such as theaters, stores, etc., where people are congregated, controlled humidity is the predominating consideration. Carrier-York Corporation has designed unit for cooling effect and some humidity control in small spaces. Short description. "Cooling Theaters with Ice," by E. \'V. Schadek. Ice and Refrigeration· Vol. 80, No. 5, May, 1931, pp. 377-379. Discussion of factors bearing upon the practical refrigeration and air conditioning of theaters, with data relative to air circulation requirements, temperatures, humidity, and Btu load. Table of water flow through pipes with various size holes in cap (for sprayers). Comparative estimates of machine and ice melting. Example work. Under, "Technical Department Starts Activities." he and Refrigeration: Vol. 80, No. 3, Mar., 1931. Use of ice as cooling medium not general as ice men nave not thought it sufficiently important. TcP rooling is a satisfactory refrigerant for theater; a" it will produce prnper tcmperatun• ;rnd humidity; investment cost low; practically noiseless; operation adjustable to atmospheric conditions; overall cost is less; safety assured; no highly skilled employees needed. "Air Conditioning with Ice in Motion Picture Theaters," by J. F. Daily. lee and Refrigera­tion: Vol. 80, No. 3, March, 1931 , pp. 212-214. Modern ice cooling plant uses water at 45° to 60° F. to accomplish the final cooling of the air. With proper means of controlling the rate of melting. the means for producing the same results as compression system is obtained. Ice cooled water sprays reduce the temperature of the air and remove moisture from it so that a low relative hu.midity is obtained. Mere copying of existing practice and substitution of media will not produce maximum efficiency. Instead of going on assumption that one condition of atmosphere only is produc· tive of human comfort, must be prepared to take advantage of all different conditions of outs'de atmosphere and from these conditions produce comfort conditions in the building in the most efficient manner. Example of comparison of costs lwtween ice and mechanical cooling: Ire-Si124 per da~-. Mechanical-$158 per day. Based on 100 days' cooling. RiYoli Theater in Baltimore. Sketch of theater aud system as installed. "Developing New Markets for Ice." hy R. T. Brizzolara. Ice and Refrigeration· Vol. 79, No. 5. Nov.. 1930, p. 346. The use of ice for air conditioning aud cooling. Investigation has shown that ice for air conditioninl! is entirely feasihle and possesses sound and special merits as a refrigerant. Some of the present burden of distribution must be removed if the new market is to examine the advantages of ice and give it due consideration. Article states that ire is priced too high to suuessfully compete in the air conditioning field. While cost of ice manufacture has gont> do"·n. little if any improwment in the distri­lrnt!on has been made. "Ice for Air Conditioning and Cooling," by R. T. Brizzolara. lee and Refrigeration: Vol. 79. No. 4, Oct., 1930, pp. 252-254. Gives markets for bulk ice cooling such as theaters, restaurants, grill rooms, homes, office suites, hotels, office buildings, hospitals, schools, food products rooms. ·Pullman car cooling. Discusses problems and disadvantages of using ice. "Space Cooling with Ice," hy C. D. Robinson. Ice and Refri~eratiun: Vol. 77. No. :'i. Nov.. 1929, pp. 305-307. Discussion of results of cooling small office building, with heating and cooling loads used. System is combination of f'orCf•d ci rculation warm air heating and ice cooling system using ducts of the heating system. Statistics: calculated cooling load: 40,000 Btu/hr for 20° F. diff. Size of office: 75' x 17' 6" x 11' 4". Ice consumption: 33 T / mo. for 24 hr. day. 21 T Imo. for 14 hr. day. Ave. temp. diff.: 6.6° F. for July; 10.7° F. for last 10 days. Conclusions from test: 1. Building with 1,800 Btu/hr per degree F. can be kept at 75° F. until the outside temperature rises above 85° F., then at least 10' F. temperature difference main· tained and require maximum of 2,400# ice daily. 2. Installation cost: $200 if part of the existing warm air system (forced circulation) ; $300 for gravity warm air system; complete, $400. 3. Cooling cost: $200-$250 per year. +. Below 1h full of ice relative humidity inside too high; cooler more than 1h full, relative humidity about right. Article contains diagrams of the system as installed. "Ice Cooling of Air---A New Steel Ontlpt." Iron Age: Vol. 129, No. 1, June, 23, 1923, p. 1343. Discusses possible efffo'ct on increasing steel