ABSORPTION PROCESS. The absorption process of refrigeration was invented by Ferdinand Cane about the year 1850. It is founded upon the fact of the great capacity possessed by water for ab sorbing a number of vapors having no boiling points, and of their being readily separable there from again by heating the combined liquid, hence it is commonly known as the absorption process. The process involves the continuous distillation of ammoniacal liquor and requires the use of three distinct sets of apparatus: (1) A set for distilling, condensing, and liquefying the am monia; (2) a set for producing cold by means of a refrigerator and absorber, a condenser, a con centrator, and a rectifier; and (3) a pumping plant for forcing the liquor from the condenser into the generator for redistillation. The three operations are each distinct from the other, but when the plant is actually working they must be continuous and are dependent upon one another, forming separate stages of a closed cycle of opera tions. An advantage of the absorption process is that the bulk of the heat required for perform ing the work is applied direct without being transformed into mechanical power. The first machines constructed on this principle were, how ever, very imperfect in operation, by reason of the impossibility of securing an anhydrous product of distillation. This was owing to the distilla tion, which is the most important operation and has of necessity to be executed in a rapid man ner, being, in the first machines, very imperfectly effected, and the liquor resulting therefrom being naturally much diluted with water. Another serious result of the above defect was the accumu lation of weak liquor in the refrigerator and the consequent necessity for constant additions of ammonia. By subsequent improvements, how ever, made by Reece in 1867-70, by Nlort in 1870, by Stanley in 1875, and by E. Carr6 in 1876, by Beck in 1886. and by !Mackay and Christiansen, Tomkins, and Pontifax in 1887, the distillate has been rendered nearly anhydrous and the absorp tion machines have been brought to a very consid erable degree of efficiency. The number of absorp tion machines which have been invented is large, and they can be described in detail only in special but the same general process is followed by all machines.
Corm-Ant Pnoci:ss. The cold-air process of re frigeration is based on the principle that the com pression of air or other gas generates heat and the subsequent expansion thereof generates cold, and cold-air machines operate by first com pressing air in a cylinder, passing it under pres sure through cooler, and finally allowing it to expand again in an expansion cylinder. The ad
vantage of cold-air machines :n•e that no chem icals of any description are required, that very low temperatures can be obtained rapidly by their use, that their construction is comparatively sim ple and their application is easy, and that the en treatises. For a general explanation of the ab sorption process the installation shown by Fig. 4 has been selected. Following first the course of the ammonia gas, we start with the generator and analyzer, which are filled with aqua-ammonia. This liquor is treated by the steam coil in the generator and the ammonia evaporates, the gas passing through the pipe A to the condenser, which is a cylindrical vessel containing a coil of pipe and filled with water. The upper coils of the con denser pipe are provided with drips, a a, in which the water vapor which is mingled with the am monia gas is condensed and led hack to the gen erator by the pipe B. The ammonia gas is cooled while passing down the condenser coil and finally liquefies at the bottom and runs through the pipe C into the receiver. From the receiver the liquid ammonia is led into the cooler, where it changes into gas and abstracts heat from the coil of brine pipe. The gas then passes to the absorber, where it meets the weak ammonia solution from the generator and is reabsorbed. The liquor is then pumped from the absorber back into the generator, where it is again heated. When the liquor in the generator is released of its ammonia it passes by the pipe D into the heater, and thence by the pipe E into the absorber, where it meets the ammonia gas from the cooler and reabsorbs it. The cooling or refrigerating, is done by the brine which circu lates through the cooler. The foregoing descrip tion applies in detail only to one make of machine, tire machine is situated externally to the chamber or store being cooled and is consequently accessi ble at all times. The of the machine is ascribed to Gorrie, who is said to have designed the first machine of this class in 1849, and improvements were made by Alexander Kirk in 1863, by Gitl•:ad in 1873, and by Windhausen, Bell-Coleman, and several others. By these suc cessive improvements the trouble from moisture and freezing had with the early machines has been largely overcome, and the present eobbair machine is a valuable and efficient device. particu larly for small installations.