Patent GB-301941-A (GB)
Title: Improvements in absorption refrigerating machines
IPC: F25B15/10
Filed: 1927-08-02
Abstract: 301,941. Munters, A. J. E. Aug. 2, 1927. Refrigerating, absorption machines for.-In a machine of the type in which a mechanical circulating device driven by forces generated in the machine is provided, and in which the pressures in the evaporator and absorber are equalized by an inert gas, the circulating device is driven by excess pressures produced in a heated pressure generator, and the circulation is controlled by sliding valves. The system shown in Fig. 1 comprises a heated pressure-generator 1, condenser 2, evaporator 3, absorber 4, and an auxiliary pressure-generator or pressure vessel 8, of smaller size than the generator 1 and heated either by the same or by independent means. The circulation of the absorption liquid is produced by a pump 5, 6, operated intermittently by excess pressure produced in the generator 8, under control of a sliding valve 10. In the position of the parts shown the generator 8 is shut off from the condenser 2 by the valve 10, and from the absorber 1 by a ball valve 21. The pressure in it therefore rises until the vapour moves the piston 6 upwards against a spring 7 and forces absorption liquid from the upper chamber of the cylinder to the absorber 4. When the piston reaches its upper position the slide valve 10 is quickly reversed, connecting the pressure-vessel 8 to the generator 1 through the pipes 23, 24 and also to the condenser 2. The pressure in the pressurevessel 8 falls to that of the generator 1, and the piston 6 is forced down by the spring 7, drawing a fresh charge of poor absorption liquid from the generator 1 and the pressure-vessel 2 into the cylinder 5. When the piston 6 reaches the lower end of its stroke, the valve 10 is again reversed to the position shown in Fig. 1, and, on the pressure in the generator 8 again rising, the cycle of operations is repeated. Absorption liquid passes by gravity from the chamber 4 through pipes 25, 20 back to the generators 1, 8. The pressure in the generator 1 remains substantially constant, the circulation of the refrigerant from it to the condenser 2, evaporator 3, and absorber 4 occurring in the normal manner. The mixture of inert gas and refrigerant vapour passes from the evaporator 3 to the absorber 4 by a pipe 19, the inert gas passing back to the evaporator by a pipe 18. In a modification of the apparatus two generators of the same size are employed, in conjunction with a double-acting pump and a slide valve which causes each generator alternately to be shut off from the condenser, the excess pressures thus produced acting alternately on opposite sides of the pump piston. In a further modification, the single-acting circulating pump is operated by excess pressures produced in the usual generator, no separate pressure vessel being employed. In this embodiment also the inert gas is positively circulated between the absorber and evaporator by means of a diaphragm pump, the diaphragm being connects to, and operated by, the piston of the absorption-fluid circulating pump. In both the above modification means, such as a flow resistance or an enlarged gas space, are provided in connection with the condenser, to prevent appreciable rise in pressure in the concenser at the moment when the excess pressure in the generator is released. Figs. 4 and 5 show an apparatus similar to that shown in Fig. 1, in which the pressure vessel 8 is contained in the generator 1, both being heated by an electrical heater 145, and the pressure vessel being of small size to obtain rapid rises in pressure and consequent speed of operation of the circulating device 146. The latter consists of connected pistons 147, 148, a slide-valve 149, and a shifting-mechanism 150 which is substantially the same as that described in Specification 255,035. The piston 147 is pressed downwardly by a spring 151, and is connected by a rod 152 to the piston 148, which forms the pump plunger. The slide valve 149 consists of a cylindrical bar with circumferential grooves co-operating with channels in the casing. The pipes connected to the circulating device are welded to a cover plate 176 screwed to the piston casing and provided with channels connected to the channels in the latter by tubes 178; the piston casing, with the slide valve, may thus be removed without disconnecting the pipes. The generator is connected through a water separator 179 to a condenser 180, from which the refrigerant passes to the evaporator 3, the latter, as well as the absorber 4, having distributing plates 181. The inert pressure equalizing gas is circulated between the evaporator and absorber by a pump 184 connected to the pressure vessel 8, the piston 185 being driven forwardly during the pressure increase period and returned by a spring 188 during the pressure decrease period. Automatic valves in a casing 189 establish the connection between the pump plunger and the chamber 3, 4. Absorp. tion liquid passes from the absorber 4 to the generator 1 by gravity, a heat-exchanger 191 being provided in the flow and return pipes 165, 190 between the absorber and generator. The pipes 162, 167, 168, 170 may also be combined with the pipes 165, 190 to form a single heat exchanger. In the position shown of the parts the generator 8 is shut off, and the consequent rise of pressure, conveyed through the pipe 170 to the underside of the piston 147, causes the piston 147, 148 to rise, the liquid contained in the piston chamber 164 being discharged through the pipe 166 to the absorber 4, whilst liquid is drawn from the absorber through the pipe 190 to the piston chamber 161. When the pistons reach their uppermost position the shifting mechanism 150 is released, moving the slide valve 149 upwards. The pressure vessel 8 is thus connected to the generator 1 through the pipes 167, J68, Fig. 5, causing an equalization of pressure, the pistons 147, 148 then moving down under the action of the spring 151. During the downward movement, liquid is drawn from the boiler into the piston chamber 164 through the piston 165, and the liquid in the piston chamber 161 passes to the pressure vessel 8 through the pipe 162. Excess liquid in the vessel 8 passes to the boiler through the pipes 167, 168. When the pistons reach their lowest position the slide valve 149 is moved downwardly and the cycle is repeated.