| 摘要 |
1,220,991. Refrigerating. BERTIN & CIE. 29 Feb., 1968 [1 March, 1967], No. 9860/68. Heading F4H. Refrigeration apparatus comprises a pure fluid switch in which gas passes alternately into the two outlet conduits, flow into the first outlet conduit producing compression and discharge of initially present gas, and flow into the other outlet conduit causing expansion and entrainment of fluid from the first conduit. As shown in Fig. 3, the first outlet conduit 44 includes a spring-loaded valve 48 controlling an outlet opening 47 and a check-valve 71 which opens to permit flow through an inlet opening 53 when the pressure in conduit 44 falls sufficiently. A pulsed gas supply is fed to the switch inlet 43 and each pulse is directed preferentially to conduit 44 causing compression and discharge of gas initially present. As the pressure increases flow switches to conduit 45 to produce a suction effect which results in expansion of the gas in conduit 44 and its entrainment by the driving gas. The relatively cool mixture then discharges through conduit 45 and valve 71 opens to charge conduit 44 for the next pulse. Two such switches may be fed by a multivibrator (Fig. 4, not shown) or the switch is modified as in Fig. 7 to operate with a constant gas supply. Switching is effected by providing a feedback path comprising restricted conduits 59, 61 and a capacitance 60. In this embodiment valve 48 is replaced by two fluid diodes 62, 63 and valve 71 by fluid diode 64. The devices may be staged (Fig. 8, not shown), each stage comprising a pair of switches and a multivibrator. The cool gas from each pair of switches is merged and used to pre-cool the gas fed to the multivibrator of the next stage and to supply the make-up gas for the first conduits of the switches of the next stage. From the third stage onwards, the relatively warm gas discharged from the switches may be used for pre-cooling in the previous stage. |
