| 摘要 |
1468745 Refrigerating PHILIPS GLOEILAMPENFABBIEKEN NV 5 April 1974 [9 April 1973] 15128/74 Heading F4H A cooling system for cooling a closed space, e.g. a dewar vessel 1, comprises a cooling coil 3 located in the closed space, a heat exchanger 11 for exchanging heat between the inlet and outlet paths of the cooling coil 3, a heat exchanger 6 in contact with the cold head 7 of a cold gas refrigerator 8, a pump 9, and a flow restriction device 10 situated between the heat exchanger 11 and the cooling coil 3. The device 10 is preferably situated inside the vessel 1, and may either be a laminar-flow or a turbulent-flow restriction. The cooling system may also be modified (see Fig. 2) for use with a plurality of dewar vessels 20-22. In this case, the system includes low and high pressure compressors 51, 52, cooling heat exchangers 54, 60, 61, a throttle valve 57, and a heat exchanger 58 wherein the cooling medium in the circuit, e.g. helium, is fully liquefied before entering the inlet pipes of the heat exchangers 23-25. In normal operation of the cooling system, for example the system shown in Fig. 1, heat leakage into the space 2 will be negligible and no heat exchange will take place in the heat exchanger 11. However, under abnormal conditions, for instance the vessel 1 being damaged, heat exchange will take place in the heat exchanger 11, causing the flow resistance in the flow restriction device 10 to increase, thereby reducing the rate at which cooling fluid is supplied to the cooling element 3. |
