Patent GB-453827-A (GB)
Title: Improvements in or relating to intermittently acting absorption refrigerating apparatus
IPC: F25B17/00
Filed: 1935-02-12
Abstract: 453,827. Refrigerating. ELECTROLUX, Ltd., Luton, Bedfordshire.-(Assignees of Platen-Munters Refrigerating System Aktiebolag; 2, Norrmalmstorg, Stockholm) Feb. 12, 1935, No. 4546. Convention date, Feb. 13, 1934. [Class 29] Absorption systems.-In intermittent systems in which solution circulates during the generating period between an unheated storage vessel 11, Fig. 1 and a heated generator 10 of small capacity, and during an ensuing evaporating and absorbing period between the storage vessel and a separate absorber 14, preferably air cooled, the weak solution from the generator passes by conduit 25 through two separate heat exchangers 26, 27 on its way to the storage vessel. In the uppermost 26, it exchanges heat with solution flowing between an equalizing vessel 12 and a standpipe 73 connected to the generator, and in the second, 27, with rich solution flowing from the storage vessel by way of conduits 66, 67, 70, 62 to the generator. The generator comprises an upright tube 10 extending into an annular chamber 20, above which is another annular chamber 24, and coils 18, 75, 16, 22 connected to several parts of the generator as shown and heated by a flue 17. Refrigerant vapour evolved in the generator flows by conduit 30, an analyser 31, conduit 33 and the inner tube of a rectifier 34 to an air cooled condenser 13, from which condensate flows to the jacket of the rectifier to cool it and thence upwards through conduit 39 to a supplementary air-cooled cooler 40 above the evaporator 15. The evaporator preferably comprises two vessels 45, 47 communicating at one end by a conduit 46 for liquid and at the other by a conduit 48 leading into a vapour dome 44. The refrigerant collected in the lower vessel 47 may be cooled by a closed-cycle condensing system 50, 49, 54, and the vessel may serve to cool brine &c. in its jacket 103. Within conduit 46 is a drain and overflow device comprising a U-tube 56 and a closed-ended tube 55. At the end of the generating period any solvent collected in the lower vessel of the evaporator and some refrigerant is forced up through tube 55 and into the drain tube 56. This is vented at 57 into the gas space of the supplementary cooler 40, and leads into a downflow conduit 58 which is heated at a point 59 in contact with heat-exchanger 27 and then extends at 60 into a shunt circuit 61, 63 of the conduit 62 conveying rich liquor to the generator. As soon as liquefied refrigerant flows through the drain conduit past the heated point 59 vapour is formed in conduit 60 and produces a local circulation of liquor in the shunt circuit 63, 61, which includes a pocket 65 containing a thermostat 64. When circulation takes place the thermostat warms up and cuts off the supply of heat to the generator. Evaporation then commences in the lower evaporator element and a vapour plug forms in the drain device 55 and stops further outflow of liquid. During the generating period the coil 16 acts to circulate the solution through the generator only, the coil 22 pumps the solution from the lower annular space to the top of the upper annular space, the coil 18 acts as a " counter pressure " pump, and the coil 75 ensures a flow between the stand pipe 73 and the generator. On the cessation of the heat supply the vapour formed in the evaporator returns by way of conduit 39, separator 34 and a conduit 76 to the equalizing vessel, and thence by a conduit 78, a buffer vessel 79 and a conduit 80 to a gas-lift device 81, where weak solution is drawn from the lower part of the storage vessel and lifted through a pipe 83 into the absorber 14. The enriched solution flows into vessel 67 and down through conduit 66 back to the upper part of the storage vessel. The excess of liquid formed during the absorption process passes down the pipe 70 and through the heat-exchanger 27 and pipe 62 to the lower annular space 20 of the generator, and eventually back into the equalizing vessel. Should some of the vapour fail to be absorbed, it collects in vessel 67 and causes an overflow therefrom, which passes to the coil 75 of the generator and reduces the effective head forcing the vapour into the gas lift device 18, the system thus being self regulating. Vapours in the vessel 67 are rapidly absorbed by pools of liquid retained in the vessel by baffle plates 69. The equalizing vessel may be large enough to take the whole liquid content of the evaporator, absorber, and connecting conduits. In the modification shown in Fig. 2 the conduit 61 of the thermostat pocket connects with the lower annular space 20 of the generator, and the evaporator drain conduit 58 is formed into a cooling jacket 90 around the riser pipe of the pump coil 18 to reduce the tendency of the pump liquid to evolve vapour after the heat supply is cut off. This arrangement also serves to empty the lower annular space during absorption. The gas-lift device 81 has an enlarged chamber to reduce noise, and for the same object two chambers in series may be used. The tubes of the absorber may be fitted with wire coils to disperse the entering vapour and avoid formation of long vapour bubbles. The generator and evaporator may be provided with anti-priming plates or gauze screens, and the liquid vessels with vertically disposed partitions to lessen displacement of liquid during transport or when the apparatus is installed on a ship or other moving vessel. The pump coil 18 may include a vessel 102, Fig. 5, connected by a swan neck bend 101 with the annular space 20. The vessel 102 is normally filled with vapour, but when pressure pulsations arise, especially at the beginning of the absorption period, the vessel sucks liquid from the annular space and prevents the formation of a gas lock in the bend 101. Noise is thus diminished. The flow of vapour from the evaporator may be stopped automatically, on abnormally low temperature and pressure being attained in the evaporator, by a valve 98, Fig. 4, connected to a bellows member 96 loaded by an adjustable spring 99 in a closed housing, the valve being arranged in the buffer vessel 81 of the gas light device to the absorber 14. A modified form of evaporator comprises a condensate collector 105, Fig. 6 located outside the wall 110 of a cabinet, a main cabinet-cooling evaporator element 112, and an ice-making element 113 adapted to enclose ice drawers and to store cold during generating periods. Solvent accumulated in the lowest part of coil 113 is lifted therefrom by vapour forming in the element 112 and passing through a pipe 116 to the condensate collector. The upper element 12 is also provided with a U-tube drain 119, 58. At the conclusion of the absorption periods some refrigerant may be left in the ice-making element 113. The upper element continues to cool at a higher temperature, and a thermostat may be arranged thereon to start a new heating period when the temperature rises.