AUTOMOBILE AIM.

Auckland Star, Volume LXIX, Issue 68, 22 March 1938, Page 18

AUTOMOBILE AIM.

AIR-CONDITIONING. ADDRESS TO ENGINEERS. CAR'S SPECIAL PROBLKMS. (My EDWARD \V. MOKKISO>O DETROIT, .Tanuary 1.". "ft is certain that in the near future some form of sate, economical aiii'iniotivp n-frijrerat in;; «y#tem will appenr. and when it does we can £0 merrily on our way, laiifrhinp at the weather man and our notoriously variable climate." Thus did the Society of Automotive Engineers, at its annual moctinpr this week, hoar tlie answer to the oft-rai*i->l question of nir conditioning of the autoinobilo. 'J.'hr answer was furnished in an analysis of the problem by L. \V. Child, of Detroit. "The application of air conditioning principles to an automobile or bus calls for somewhat different considerations than the problem of conditioning a home or public building," Mr. Child asserted. "The space per person, especially in the bus, ia considerably smaller than that found in the most crowded of buildings. The air for conditioning must be delivered in close proximity to the passengers, giving little chance for mixing it with the surrounding air before coming in contact with the occupants. Unlike the building, the car is moving at widely varying speeds, causing correspondingly widely varying amounts of fresh air to leak into the car, and so upset any care-

fully figured conditions. There is also the eerious problem of available epace for equipment. «

Difficulties in Can. ' ■ "A cold draught will do more to ruin a conditioping job than almost any other factor. In a building, the supply outlets are carefully located to obviate this trouble, whether the eystem is used for heating or cooling, by placing them far enough - away to allow the air to slow down before coining in contact with the occupants. Aβ tliis is impossible in a car, it is necessary carefully to direct the air away from the occupants and supply it at the highest possible temperature and the lowest possible velocity, whether the system be for heating or cooling.

"The leakage of outside air into a car or bus would seem to be an uncontrollable factor. It varies with the epeed, the wind velocity and direction, the type of construction and the age of the vehicle. The most logical way to attempt to control leakage is to supply enough outside air, properly conditioned, to cause the air in the body to leak out.rather than in. Rough tests have ehownthat 00 to 80 cubic feet of. air per miniate delivered from outside into the'body will stop leaks on most of to-day^fbur-door cars at speed* up to 60 miles per hour.

"Considering the atmosphere inside the car, the most annoying phenomenon of winter driving is the formation of fog on the windows and. the odour of wet woollen clothes and stale tobacco emoke. If we supply sufficient fresh air to eliminate the possibility of fog, experience has shown we will also eliminate the odour and smoke, stale or otherwise.

"Considering the domestic market, it is safe to assume that a conditioning system will not be installed for summer conditions alone, but will be designed for year-round operation. In other word*, it will have a heating coil operated by hot water and a cooling coil operated by a separate refrigerating pyetem, either of which can be operated independently of the other. Such a system is designed to take take care of a maximum load.

System Too Expensive. "From a power standpoint this system fe too expensive to operate in buildings for comfort conditioning, but in a motor vehicle the heat ie available and the cost of operating a refrigerator system, necessarily designed for maximum conditions, will be substantially the same for full load as for any fraction of full load. Therefore, the operating cost of this system is not a deciding factor in motor vehicles. "In selecting a refrigerating system for a motor vehicle we will again encounter many problems not found in stationary systems. Space is at a premium; vibration may cause break* in lines; power is available, but at widely varying speeds; occupied space is small, giving rise to serious dangers from leaks; accidents may entrap passengers in a space open to refrigerant odours. "Wi.en gasoline is vaporised it absorbs heat in the same manner as. any other liquid. It has, therefore been proposed to utilise this principle for cooling motor vehicles. Assuming a car operating at 30 niiiles per hour nnd running at 10 miles per gallon, the beet eooling'effect possible would lie roughly one-third of a ton, or about one-thiifl the required rate for comfort. "The most logical system appears to be the use of a compressor, operated from the engine through a suitable variable si>pi»d drive. Such a eysteni will require n minimum space and not over two hors-'-powcr, a figure well below ths power required to operate the present radiator fan."—(Copyright: N.A.N. A.)