Patent GB-238223-A (GB)
Title: Improved process of and apparatus for the production of cold
IPC: F25B15/10
Filed: 1925-07-28
Abstract: 238,223. Platen-Munters Refrigerating System Aktiebolag. Aug. 8, 1924, [Convention date]. Refrigerating, absorption systems for. -A refrigerant is separated as a vapour from a solution at a. low temperature to produce cold and is reabsorbed without undergoing condensation, a n auxiliary medium being employed to mix with or absorb the solvent, and the resulting mixture or solution being heated in a boiler or generator to expel the solvent and concentrate the auxiliary medium. The circulations are con. tinuous and are effected entirely by thermal changes in a closedcycle apparatus, working under pressures lower than those normally required in systems where the refrigerant vapour undergoes condensation. Ammonia may be used as the refrigerant, with water as the solvent and an alkali lye such as a mixture of potassium hydrate and sodium hydrate as the auxiliary medium. Alternatively, carbonic acid may be used as refrigerant, sulphurous acid as absorbent, and carbon disulphide as auxiliary medium; brine also may be used as the auxiliary medium. A cooler 1, Fig. 1, contains a solution of ammonia in water, a generator 2 contains an alkali solution, and the ammonia separated in the cooler 1, with abstraction of heat from the substance to be refrigerated, is absorbed in a vessel 3 in which steam expelled from the generator is cooled and condensed by a cooling-jacket 7. The refrigerant vapour rises to the absorber through a pipe 4 terminating in a perforated pipe 6 underneath the liquid, and the solution overflows from the absorber through a pipe 5 depending into the liquid in the cooler. The solvent flows from the bottom of the cooler through a pipe 10 terminating in a coil 12 and riser pipe in the generator 2, and the concentrated auxiliary medium flows through a pipe 9 from the generator to the top of the cooler, the pipes 9, 10 forming a heat interchanger 11. The steam evolved in the generator passes through a pipe 8 to the absorber. The refrigerant selected should have a critical temperatures below the lowest temperature of the cooler, to prevent condensation in the cooler, and the solvent should have a critical temperature which is near the temperature of the generator. To eliminate dissolved refrigerant from the solvent flowing to the generator, the arrangement shown in Fig. 2 may be adopted, in which the refrigerant is expelled from the cooler 1 between particles of solvent rising through a pipe 15 into a gas separator 14. Refrigerant vapour is separated therein and flows through a pipe 18 into an auxiliary absorber 17 surrounding the separator, and is partly absorbed therein by solvent flowing through a trapped overflow pipe 5 from the main absorber 3, which may be a gilled vessel cooled by the atmosphere. Unabsorbed refrigerant rises through a pipe 20 into the main absorber, and the solution flows from the absorber 17 back to the cooler. The solvent flows from the separator 14 through an extended pipe 16, 9 to the generator 2, and exchanges heat with concentrated auxiliary medium flowing from the generator through a pipe 10. In a further modification, the solvent itself is evaporated with the refrigerant in the cooler, and is absorbed by the concentrated auxiliary medium in a vessel separate from the main absorber. The refrigerant vapour flows on to the main absorber, while the mixture of solvent and auxiliary medium flow to the generator for concentration of the medium and expulsion of the solvent vapour to the main absorber. The cooler and intermediate absorber in this arrangement are fitted with perforated trays.