Refrigerated Railway Waggons. 



219 



Refrigeration Experiments with Railway Waggons. 



Experiments have been conducted in Denmark as to the 

 best system of maintaining railway cars at a low temperature. 



Two cars belonging to the State Railways were cooled by 

 means of ice upon a system analogous to that adopted in 

 France, while in a third car ammonia was used as the refriger- 

 ating agent. 



The latter was an ordinary car, provided with apparatus 

 which permitted the circulation of ammonia gas, set free into 

 pipes arranged in horizontal coils inside the car. At one end 

 of the car, outside, are fixed two iron cylindrical bottles, which 

 contain the necessary liquid ammonia, i.e. 80 kilogrammes 

 (about 176 lb.). These communicate at the bottom, by means 

 of a tube provided with a tap and automatic regulating valve, 

 with the coils inside. There are two of these, placed along 

 the end walls inside the car ; each consists of two ranges of 

 horizontal tubes occupying the whole upper half of the free 

 space between floor and roof. 



The ammonia set free in the first set of pipes is conducted 

 into the second by a tube in the roof; from there into a 

 cylinder placed transversely across the car underneath at the 

 end carrying the iron bottles. This cylinder is connected by 

 a tube with a second receptacle fixed at the outside end of the 

 car, above the cylinder, and provided with a graduated glass 

 tube forming a water level, and with a safety valve to let 

 the air out. Cylinder and receptacle are filled with water, 

 the latter, however, to a slight depth only, and serve to absorb 

 the ammonia gas as it is vapourised ; the quantity of gas 

 dissolved, and therefore utilised, is measured by the increase in 

 height of the liquid in the upper vessel. 



As the absorption of the ammonia liberates heat, the lower 

 cylinder has to be cooled. For this purpose there is placed 

 in the roof of the car a reservoir of water, which is connected 

 with a horizontal pipe, which runs parallel to and above the 

 cylinder, and is provided with four taps which allow the water 

 to flow drop by drop on the cylinder. This cooling was only 



