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530 CHAPTER 27 1.965 Guide And. Data Book. Harry Bucbberg: Cooling load from thermal, network solu tions (ASHAETransactions, Vol. 64,1958, p! 111)."'' u Harry Buchberg: Cooling load from pretabulated impedances (ASHAETransactions, Vol 64,1958, p. 503). ~ * u W. B. Drake, Harry Buchberg' and D. Lebell:-Load calcu lations using pretabulated admittance functions (ASHAE-Trans- ACTtONS, VoL 65,1959, p. 515). u W. B. Drake, Harry Buchberg, and D. Isbell: Transfer admittance functions for typical composite wall sections (ASHAE Transactions, Vol. 66, 1959, p.523)." ' * * Walter Koch, B. H. Jennings, and- C. Mi Humphreys: ASHRAE Research Report No. 1715^-Environmental Study II--Sensation, responses to temperature aod humidity under still air conditions' in the comfort range (ASHRAE Transac tions, Vol. 66, 1960, p. 264). 1T Evaluated Weather Datajar Cooling Equipment Design (Fluor Products Co., Santa Rosa, Calif., 1st edition, 1958). i 11 Engineering Weather- Data (Army, 'Navy, and Air Force Manual TM5-7SS, 1963). u L. W. Crow: Study of'Weather Design Conditions (.Bulletin, ASHRAE Research Project No. 23,1964). ** C. C. Boughner: Canadian MSerological Memoirs No. 6 (Meterokwical Branch, Department* of Transport, Ottawa, Ontario, Canada, 1960). n W: V. Consdario and L. J: Pecora: Minimal replenish ment air required for living spaces (ASHVE- Transactions, Vol. 53, 1947, p. 127). B Recommended Safe Practice of. the NBFU for. Hospital Operating Rooms (National Board of'Fire Underwriters Pam phlet No. 56). * P. Moon: Proposed standard solar- radiation curves for engineering use (Journal of the Franklin Institute, Vol. 230, November 1940, p. 583). ** C. O. Mackey: ASHVE Research Report No. 1268-- Summer weather data and sol-air temperature--Study of'data for Lincoln, Nebr. (ASHVE Transactions, Vol. 51, 1945, p. 93). ** C. O. Mackey and E. B. Watson: Summer weather data and sol-air temperature-^Study of data for New York City (ASHVE Transactions, Vol. 51, 1945, p. 75). * G. A. Heodrikson and J. H. Walker: Summer cooling for comfort as.affected by solar radiation (Heating and-Ventilating, Vol. 29, November 1932, p. 14)." n Tobies of Computed Altitude and Azimuth (U. 8. Navy Dept. Hydrographic Office Bulletin No. 214, Vol. 1-9; 1940). * The, American Nautical Almanac (U. S. Naval:Observatory, annual). * F. C. Houghten, J. L, Blackshaw, E. M. Pugh, and-Paul McDermott: ASHVE Research Repost No. 923--Heat trans mission as influenced by beat capacity and solar radiation (ASHVE Transactions, Vol. 38, 1932, p. 231). J: S. Alfonl, J. E.Ryan, aod F. O. Urban: Effect of heat storage and varia tion in outdoor temperature and solar intensity on beat trans fer through walls (ASHVE Transactions, Vol. 45, 1939, p. 369). Victor Paschkia: Periodic beat flow in building wails determined, by electrical- analogy method: (ASHVE. TransactionSj VoL 48, 1942, p. 75). G. O. Mackey and-L. T: Wright,- Jr.: Periodic heat flow--Homogeneous walls, or. roofs (ASHVE-* Transactions, VoL 50, 1944, p. 293). C. O.-Mackey and L. T. Wright, Jr.: Periodic'heat flow^--Composite walls or roofs. (ASHVE Transactions, Vol. 52, 1946, p. 283). H. A. Johnson: Periodic heat transfer at the inner surface of a homogeneous: wall (ASHVE Transactions, Vol. 54, 1948. p. 143). W.F. C. Houghten,-Carl- Gutberlet, and. A. A.. Rosenburg: The effect of solar radiation.on the heat transmission .through walls (American Society, of. Testing Materials. Symposium oh. Thermal Insulating Materials, 1939). " F. C. Houghten. H-..T-. Olson, and Carl-Gutberlet: ASHVE Research Repost.No. 1>157--Summer cooling load as affected/ by heat gain through dry, sprinkled and water covered-, roofs (ASHVE TRansactions,.Vo1; 46; 1940, p. 231). ** F.,C. Houghten, Carl Gutberlet, and A. J: Wahl: ASHVE' Research Report, No. lOOl-Cooling requirements of: single rooms in s modem office, building. (ASHVE Transactions,' Vol. 41, 1935, p. 53). ~ ** J. N. Livermore: Study of actual.vrf- predicted: cooling,load on an air conditioning ByBtem. (ASHVEtTransacnoNS, Vnl:-49, ' 1943, p. 287). . 1 * F. C. Houghten, E; C. Had), S- ll. Taimuty, aiid ;.Cari Gutberlet: ASHVE- Research. Report^No'. 1195t-Heat.j^un, through walls aod roofs as.affected by,solar.radiation, (ASHVE. Transactions, Voh 48, 1942,- p. 91). ' (... o > .*. . ** J. P. Stewart: Solar heat'-min; through.-walla and -roofS) for cooling load calculations (AoHVE Transactions, Voh. 54, 1948, p. 361). * G. V; Parroelee aod W. W. Aqbele: ASHVE, Research, Report No. 1442^-Radiant energy ` emission of atmosphere and ground (ASHVE Transactions, Vol. 58,1952,"p. 85). " 77 D. Brunt: Radiation in the atmosphere '(Supplerrient to the Quarterly Journal of the Royal Meteorological Society, VoL 66, 1940). u N. Oririk aod L. F. Schutrum: Solar, heat gains through slat- type between-glass shading devices (ASHRAE Transactions* Voh 60, 1960, p. 359). *** '' **G. V. Parmelee and D. J. Vild:-ASHVE RgsimnrTff re port, No. 1485--Design data for slat-type sun shades for. use in load estimating (ASHVE.Transactions, VoL 59, 1,953, p. 403)7 " Personal communication from C. W. Pennington related to work in progress on ASHRAE Research Project RP-30, for which papers will; be published. " C. W. Pennington and W: A. Smith: Shading coeffidents for glass block panels (ASHRAE Transactions, Vol. 70, 1964)'.. N. Osiaik and L. F. Schutrum: Heat gain through windows shaded by canvas awnings (ASHRAE- Transactions, Vol. 64, 1958, p. 463). N: Osiaik and L>. F. Schutrum: Heat gain through windows shaded by metal awnings (ASHRAE Transactions. Vol. 65, 1959, p. 311)......................................... " ** C. 8. Leopold: The mechanism, of heat transfer, panel cooling, heat storage (Refrigerating Engineering, July 1947;' p. 33). C. S. Leopold: Hydraulic analogue, for the solution of problems of. thermal storage, radiation, convection and con duction'(ASHVE Transactions, Vol. 54, 1948, p. 389). * C. O. Mackey and N. R. Gay: Heat* gains, are not coolinz loads (ASHVE Transactions, VoL-55, 1949, p. 413).............. * C. O. Mackey and N; EL Gay:. Cooling load from sunlit glass (ASHVE Transactions, Vol; 58, 1952, p. 321). * Application. Engineering Standards, for Air Conditioning for Comfort (Air Conditioning and Refrigerating Machinery Association, Inc., 1947, p. 8). '47 C. M. Ashley: Psychrdmetric factors in the air conditioning estimate (ASHVE Transactions, YoL 56, 1949, p. 91). ** W. G. Darley:-Cooler-footcandles for. air conditioning (ASHVE Transactions, VoL 46, 1940, d. 367). IES-ASHVE Joint Committee oh Ughting and Air Conditioning: lighting and.air conditioning design factors (ASHVEJoobnac Section; Heating, Piping and Air Conditioning, September 1941, p. 605). H. M. Sharp: lighting and air conditioning (Heating and Ventilating, November 1942, p. 35). *' W. L. Mam: Commercial Gas Kitchen Ventilation Studies (AmericahGas Association Laboratories, Research Bulletin. No' 90, March 1962). " Gas arid Electric. Consumption in Two College.- Cafeterias (American Gas.'Association, October 1950). " A Comparison of Gas and Electric Usagefor Commercial Cook ing (American Gas Association, 1949). ** E. A. Jahn: Commercial Kitchen Ventilation (Americao Gas Association, April 1960, p. 24) and other sources. Compiled' by. J,. P.* Stewart and; K. A. Jahn from, various sources. M H. T. Gilkey, D. R, Bahnfleth.and R. W. Roose: Cooling a small residence, with a two-horsepower, mechanical condensing unit (ASHVE Transactions,'VoL 59,1953, p. 283). D. R. Bahnfleth, C. F. Chen and H. T. Gilkey: Coolings small residence using a perimeter-loop duct system (ASHVE' Tbansactions, Vol. 60, 1954, p. 271). W. S. Harria 'and P. J: Waibler: Cooling studies in a research home (ASHVE Transactions, Vol. 60, 1954, p. 487). H. T. Gilkey, W. S. Stoecker, and S. Konzo: Effects of weather conditions on cooling unit' operation in a residence (ASHAE Transactions, VoI.61; 1955, p. 255). H Load Calculation for Residential Winter and-' Summer Air Conditioning (National Warm Air.Heating.ahd.Air Conditioning Association, Manual J). Standard for Application of. Y>tar-Rovna Residential Air .Conditioning (Air..Conditioning and Refrigeration Institute, Stondord 230-62). Coding Load Calculation Grade (The Institute of- Boiler and- Radiator Manufacturers, Guide CS0, 3rd edition). * The AU-Industry Procedure for Heat Gam Calculation and Equipment Selection (Technical Information Feature, The Bulle tin, National Warm Air Heating and Air, Conditioning Associ ation, May 1961). 17 Standard 210-62: Standard. for Unitary Air-Conditioning Equipment; Standard tifi: Standard for Unitary Heat Pump Equipment; Standard.250-62: Standard far, Unitary.Beat-Operated Atr-Oonditioning Equipment (Air Conditioning and Refrigeration Institute}-. American Standard ASA Z21.40.1-. Approval Require ments for Gas-Fired Absorption Air Conditioning Appliances; American Standard ASA Z21.40.2: Approval Requirementsfor Gas Engine-Powered Air. Conditioning. Appltcances (American Gas Association, Inc.). CHAPTER 28 REFRIGERATION LOAD Heat Gains from Walls, Roofs, and Floors; Air'Change load; Product food; Heat Gains from People, lights and Other - Sources; Short Method Calculations TO SELECT refrigeration equipment which will result in ; a balanced system it is first necessary .to calculate the., heat load of the refrigerated space. There are four general where x\, xt, xt, etc., are the thicknesses and ki, it, i, etc., are the conductivities of the several materials used. After establishing the coefficient of transmittance U the sources of heat: (1) wall heat gain; (2) air changes, (3) product heat gain is given by the basic equation: load, and (4) miscellaneous loads, such as the heat gain,from . 9.- UA&t (3) men working in the room, lights,, electric motors and other, where heat producing equipment.' For & complete calculation, each of the four sources should be'evaluated separately to deter .. Q *= heat leakage, Btu per hour. ... mine the totaL A ~ outside area of section, square feet. At = difference between average outride temperature and " WALL HEAT GAIN ' ~ average refrigerated space temperature, Fahrenheit - degrees. The heat gain through walls, floor, and ceiling -will .vary with the following factors: type of. insulation, thickness of insulation, construction, outside wall area, and temperature' difference between'refrigerated space and ambient air. The heat transfer factors at various temperature differences, are listed in Table 1. The thickness of cork referred to.in this table is' actual cork or equivalent insulation thickness, not the overall wall thickness. The comparative values'of various insulation materials can be found in Chapter 24, Table .4. ' ' . The overall coefficient of heat transmission.;U, of the .wall'' can be found by the following equation: The refrigeration industry has tended to standardire the minimum insulation of a refrigerator.'Table 2 is a list'of recommended minimum insulation thicknesses.' Installations have been made with no insulation in the floor, but this type of installation will not be discussed due to the lack of 'au thentic data. ) The outdoor design temperatures for the major cities in the United States can be found in Table 1, Chapter 27.. . If the refrigerator is exposed to the sun, additional heat will be added to the heat load. For practical purposes, the tem perature difference can be adjusted to compensate for the sun effect. The values given in Table 3 are applicable throughout the 24 hr period and are added to the ambient temperature in calculating wall heat gain. where U coefficient of heat transmission, Btu per (hour) (square foot) (Fahrenheit degree)... ' x -- thickness of the wall, ,. . k " conductivity of material in wall, Btu per (hour) (square foot) (Fahrenheit degree per inch thickness). /.s inside film or surface conductance, Btu per (hour) .(square foot)(Fahrenhat degree). -7 U " outside film orsurface conductance, Btu per (hour) (square foot) (Fahrenheit degree). fi and ft are frequently used as 1.65 for still air:-If the outer curface is exposed to weather, /, is increased to 6. ' With thick walls and low conductivity, the resistance x/k ~Jes If 90 small that 1//,- and iff, have little effect and can be omitted from the calculation. As walls are seldom made of one material, the value x/k represents the composite resistance ^ulue of the several materials used in series to the heat flow, aud for a wall with flat parallel surfaces of materials I, 2, 3, etc., AIR CHANGES Each time the door is opened some outside air enters the storage room. The temperature of this warm outside air must be reduced to the storage temperature, thus adding to the re frigeration load. It is difficult to determine the load with any degree of accuracy. The traffic in a refrigerator usually varies with its size or volume. The number of times doors are opened is dependent upon the volume rather, than the number of doors. The air changes listed in Table 4 are based'on practical experience.- *;'.*. The heat removed to reduce one cubic foot of air from out side conditions to the refrigerator temperature is listed in Table 5. Inlet air temperature listed in Table-5 refers to the air which enters the refrigerator when the doors open. Table 4 does not apply, if outdoor air is provided. The ventilating load under these conditions will replace .the door opening load, if greater. To calculate the load due to ventila tion, change the ventilating cubic feet per minute to cubic feet per 24 hours (cfmX60X24) and use Table 5 for the heat load per cubic foot of air. PRODUCT LOAD A product placed in a refrigerator at a temperature higher than the storage temperature will lose heat .until ii reaches the storage temperature. The quantity of heat to be removed for TC 2.1, Lc*d may be calculated from a knowledge of the product, including its state upon entering the refrigerator, its final state, its 531