Document zbpNeg5Zeg2Mj60ndB0GVzvJn

HEATING ventilating AIR CONDITIONING GUIDE 1944 preferably near the front of the vehicle so as not to contaminate this supply with exhaust fumes and road dust. Of the SO cfm circulated per person, about 8 to 10 cfm are outside air and the remainder is recirculated. Power for the motor driving the centrifugal fans is obtained from the bus battery. More recently a coach design has been brought out which provides for a number of return air outlets below the seats; these permit return air to enter a longitudinal duct below the floor. The filters and evaporator are located in this duct near the front of the vehicle. In this instance a central heating coil utilizing waste heat from the coach engine is also located in this duct. Conditioned air is delivered through a pair of vertical ducts to a package rack distribution scheme. Summer conditioning systems for these vehicles range in cooling capacity from 36,000 to 48,000 Btu per- hour. Mechanical compression systems using dichlorodifluoromethane are used, and are powered bywater cooled, gasoline engines of approximately 14 hp. Complete systems add from 800 to 1300 lb to the weight of a coach. Sometimes an auxiliary generator driven by the air conditioning engine is used which serves to help charge the bus battery and thus offsets the power drain imposed by the ventilating blower. Belted reciprocating compressors and direct driven V-type arid rotary compressors are used, with engine speeds up to about 1800 rpm. Air cooled condensers for this service require about 5000 cfm of .outdoor air, and this is provided by either centrifugal or propellor type fans belted or direct driven by the air conditioning engine. Preventing noise and vibration from affecting passengers is of vital importance. Installations must be made so that quick daily servicing of the engine is possible. In all cases fuel is obtained from the main bus tanks, and in some cases the main engine jacket water cooling system is used to cool the air conditioning engine. .. . . In the more deluxe equipment after the driver has started the air con ditioning engine by means of its own cranking motor, the engine speed is modulated automatically as the reffigeration demand is partially-met, and if this demand is then fully met, the engine is stopped thermostatically. Restarting when the cooling thermostat is no longer satisfied is accom plished either automatically or manually. The various protective and automatic devices on the refrigerant and engine systems make some of the bus air conditioning control systems quite complicated. AUTOMOBILE SUMMER AIR CONDITIONING Recently summer air conditioning has been applied to automobiles. The average present day automobile with little insulation, large, single glazed window areas, and high infiltration and exfiltration losses requires about 15,000 Btu per hour of cooling capacity. One system utilizes a reciprocating compressor belted from the main engine fan shaft thus operating at varying, speeds up to 3000 rpm. The resulting refrigeration capacity varies from about 6000 Btu per hour at idling speed to 24,000 Btu per hour at maximum car speed. A dry air condenser is placed in front of the engine radiator, and the liquid and suction refrigerant lines run back under the car floor to the 702 CHAPTER 38. TRANSPORTATION AIR CONDITIONING evaporator which is located in back of the rear seat. Conditioned air is delivered into the car just above the shelf near the back of the rear seat. A: return grille is provided under the rear seat, and the. recirculated air is filtered. Outdoor air is provided by infiltration. Power for the air circulating blowers is obtained from the car storage battery. Equipment of this nature increases the car weight approximately 200 lb. REFERENCES Railway Passenger Cars Summary Report on Air Conditioning of Railroad Passenger Cars, by Division of Equipment Research, Association of American Railroads, November 24, 1936. Engineering Report on Air Conditioning of Railroad Passenger Cars, by Division of Equipment Research, Association of American Railroads, April 15, 1937. Report on Performance and Cost of Operation of .1937 Internal Combustion Engine Mechanical Compression Equipment for Air Conditioning Railroad Passenger Cars, by Division of Equipment Research, Association of American Railroads, May 1, 1937. Report on Relative Performance of Air Filters, by Mechanical Division, Association of American Railroads, January 15, 1938. Air Conditioning of Railroad Passenger Cars, by L. W. Wallace and G. G. Early, Jr. {A.S.M.E. Transactions, November, 1937). Improved Methods of Railroad Air Conditioning, by A. E. Voigt (Refrigerating Engineering, July, 1940, p. 16). Buses and Automobiles Iso-Thermal Manifold and the Conditioned-Air Unit Used on Nash Cars, by . E. Monson (Society of Automotive Engineers Journal', January, 1938). Summer and Winter Air Conditioning of Automobiles and Buses, by L. W. Child (.Heating and Ventilating, March, 1938, p. 38). Air Conditioning Takes to the Highways (Heating, Piping and Air Conditioning, May, 1938, p. 314). Fleet of Air Conditioned Buses West Carries Demountable Units (Heating and Ventilating, May, 1938, p. 30). , Conditioned Air for Automobiles (Heating and Ventilating, May, 1938, p. 44). Air Conditioning of Automobiles and Buses, by L. W. Child (Society of Automotive Engineers Journal, June, 1938). Bus Air Conditioning, by Jerry Hicke (Heating, Piping and Air Conditioning,Gctober, 1938, p.639). Bus Air Conditioning, by A. J. Mallinckrodt and Lars Hanson (Refrigerating Engi neering, June, 1939, p. 388). Problems in Air Conditioning Automobiles, by F. J. Linsenmeyer (Society of Auto motive Engineers Journal, July, 1939). Packard Offers Automobile Air Conditioning System (Heating, Piping and Air Conditioning, December, 1939, p. 756). Airplanes Flight in the Sub-stratosphere, by J. C. Edgerton (Society of Automotive Engineers Journal, 39:484-6 December, 1936). Steam Heating for Modern Air Transports, by Jack McGuire (Herding and Ventilating, February, 1937, p. 37). Comfoft Aloft (Heating and Ventilating, October, 1937, p. 40). 703