JPS5969677A - Low-temperature tank for cooling - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a low temperature chamber for cooling, for example, a tensile test piece.

Conventionally, this type of low temperature chamber, for example, as shown in Fig. 1,
A corrugated pipe 3 is immersed in a refrigerant 2 housed in a container 1 having an insulated structure, and a cooling liquefied gas such as liquid nitrogen is supplied into the corrugated tube 3 to vaporize it, and at the same time, the refrigerant 2 is stirred by a stirring blade 4. Accordingly, a low-temperature bath is known in which the temperature of the refrigerant 2 is lowered to an extremely low temperature using the heat of vaporization of the cooling liquefied gas.

However, in the conventional cryogenic chamber shown in FIG.
Because of the configuration, it takes time for the temperature of the refrigerant 2 to reach a temperature corresponding to the flow rate after changing the flow rate of the cooling liquefied gas. There were problems such as difficulty in delicate temperature control.

Conventionally, the liquefied gas contained in the inner and outer multi-tanks is equipped with an inner tank with a sealed space formed on the outer periphery that can supply and exhaust helium as a heat exchange medium, and an outer tank with the inner tank inside. A low-temperature device configured to adjust heat exchange between each other by adjusting the amount of helium supplied to the space and the concentration of helium in the space, and as a result, the temperature of the liquefied gas stored in the inner tank is set and maintained at a target temperature. Tanks are known (Japanese Patent Publication No. 5
4-91850). However, the above-mentioned cryogenic chamber uses expensive helium gas as a heat exchange medium, and actively exhausts helium gas from the space in order to lower the thermal conductivity between the liquefied gases contained in the internal and external phases. Since exhaust equipment such as a vacuum pump is required, there is a problem that not only the cryostat as a whole becomes complicated and expensive, but also the running cost increases. Furthermore, in the above-mentioned conventional apparatus using a heat exchange medium, after the temperature of the helium gas supplied to the space has decreased, the liquefied gas contained in the inner tank is cooled by the liquefied gas contained in the outer tank. There was a problem with poor response when cooling the liquefied gas in the tank.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a low temperature bath that can efficiently cool a refrigerant and accurately control the refrigerant temperature.

Embodiments of the present invention will be described below with reference to FIGS. 2 and 3.

FIG. 2 is a schematic diagram showing one embodiment of the present invention, and FIG.
The figure is a detailed view corresponding to the cross section taken along the line ■-■ in FIG.
The refrigerant container 10 is Freon-12 or Freon-1.
3 (trade name, respectively) or methyl alcohol, etc., and is configured to immerse an object to be cooled, such as a tensile test piece, in the refrigerant 11, and a guide plate 12 is provided near the bottom of the refrigerant container 10. is arranged horizontally, and a stirring blade 14 rotated by a motor 3 is arranged on one end side of the guide plate 12, and the stirring blade 14 and the guide plate 12 circulate and flow the refrigerant 11 in the vertical direction to stir it. A cooling nitrogen gas circulation path 15 is formed on the entire outer circumferential side of the refrigerant container 10, and a cooling liquid nitrogen storage section 16 is further formed on the outer circumferential side of the circulation path 15. The passage 15 and the storage section 16 are communicated through a vent hole 19 formed in the upper part of the partition wall 17 separating the two, more precisely, in the partition wall 17 slightly above the liquid level of the liquid nitrogen 18 stored in the storage section 16, In addition, an exhaust hole 21 for naturally discharging nitrogen gas is formed at a predetermined location of the top plate 20 adjacent to the circulation path 15.Furthermore, a fan 22 is installed inside the circulation path 15 as a blower. is provided, and its fan 22 is connected to a motor 23 disposed outside the circulation path 15, and further inside the circulation path 15,
A plurality of guide plates 24 that guide the nitrogen gas in the horizontal direction, that is, in the circumferential direction along the outer peripheral surface of the refrigerant container 10, are provided with so-called guide plates 24 in the vertical direction to prevent the nitrogen gas from flowing in the vertical direction as much as possible. It is set up to have a labyrinth structure.

Therefore, as the liquid nitrogen in the storage section 16 evaporates, the liquid nitrogen itself becomes extremely low temperature, and at the same time, extremely low temperature nitrogen gas is generated, and the nitrogen gas flows into the circulation path 15 through the ventilation hole 19. By flowing in the circulation path 15, heat exchange occurs through the nitrogen gas at the gate between the refrigerant 11 and liquid nitrogen, and as a result, the refrigerant 11 is cooled, and the temperature between the refrigerant 11 and the liquid nitrogen 18 is Since the substantial heat transfer coefficient changes depending on the convection state of the nitrogen gas in the circulation path 15, the convection state of the nitrogen gas in the circulation path 15, that is, the flow rate in the circumferential direction of the refrigerant container 10 is changed once. This allows the cooling rate of the refrigerant 11 to be adjusted.

Furthermore, a temperature sensor 2 is placed inside the coolant container 10.
The temperature sensor 25 and the heater 26 are electrically connected to the controller 27, and the temperature of the refrigerant 11 detected by the temperature sensor 25 is equal to or higher than the preset temperature. In this case, the fan 22 is rotated by the motor 23 to forcefully flow the nitrogen gas in the circulation path 15, and conversely, when the temperature of the refrigerant 11 is below the preset temperature, the fan 22 is rotated by the motor 23.
or the fan 22 is stopped and the heater 26 is energized to generate heat.

Furthermore, a liquid nitrogen supply pipe 29 through which a flow rate adjustment valve 28 is inserted is connected to the housing part 16, and a liquid level detector 30 is inserted into the housing part 16, and these &1
The EiJ adjustment valve 28 and the liquid level detector 30 are connected to the controller 2.
7, and by opening the flow rate regulating valve 28 based on the output signal of the liquid level detector 30 when the liquid level in the storage part 16 falls below a certain level, It is configured to keep the amount of liquid nitrogen 18 in the storage portion 16 substantially constant.

Incidentally, the reference numeral 31 in FIGS. 2 and 3 is a heat retention unit.

As is clear from the above-described configuration, in the above-mentioned cryostat, nitrogen gas generated by evaporation of liquid nitrogen 18 enters the circulation path 15 through the ventilation hole 19 and fills the circulation path 15, and as a result, the circulation path 15 is filled. Heat exchange occurs between the cold liquid 11 and the liquid nitrogen 18 using the nitrogen scum in the passage 15 as a heat transfer medium, and the refrigerant 11 is cooled. In that case, the heat transfer coefficient between the refrigerant 11 and the liquid nitrogen 18, or more precisely between the nitrogen gas in the circulation path 15 and the wall surface of the circulation path 15, is determined by the temperature boundary that occurs on the nitrogen gas side. In relation to the layer, the forced convection of the nitrogen gas increases the size, so if the temperature of the refrigerant 11 is considerably higher than the desired target temperature, the fan 22 rotates at high speed to circulate and flow the nitrogen gas at a high speed. When the temperature of the refrigerant 11 is close to the desired target temperature, the fan 22 rotates at a low speed or stops, thereby suppressing the flow of nitrogen gas. As a result, the refrigerant 11 is rapidly cooled when the temperature is high, and slowly cooled or simply kept cool when the temperature is low.
By controlling the rotation of the refrigerant 11, the temperature of the refrigerant 11 can be easily set and maintained at the target temperature. In addition, refrigerant 1
1 becomes supercooled, the heater 26 is energized to generate heat, and the stirring blade 1 is turned on to equalize the temperature of the refrigerant 11.
Of course, the refrigerant 11 is constantly stirred by the refrigerant 4.

As is clear from the above description, according to the cryostat of the present invention, a cooling nitrogen gas circulation path and a liquid nitrogen storage section are sequentially formed on the outer circumferential side of the refrigerant container, and the liquid nitrogen generated by evaporation and vaporization is Filling the circulation path with nitrogen gas and using the nitrogen gas as a heat transfer medium between the refrigerant and liquid nitrogen, and forcing the nitrogen gas to flow in the circumferential direction of the refrigerant container by a blowing means. Since the heat transfer coefficient is changed by adjusting the flow rate according to the temperature of the refrigerant 7-, the cooling rate of the refrigerant by liquid nitrogen can be easily and accurately controlled, and as a result, the temperature of the refrigerant can be adjusted to any desired target. The temperature can be maintained accurately. Further, the cryogenic chamber of the present invention uses nitrogen gas produced by evaporation of liquid nitrogen for cooling as a heat transfer medium between the refrigerant and the liquid nitrogen, and uses the nitrogen gas to change the cooling rate. Since it is configured to change the flow rate, the overall configuration can be significantly changed compared to a conventional cryogenic chamber that uses helium gas as a heat exchange medium and controls the cooling rate by changing the amount and concentration of helium gas. can be simplified,
Furthermore, in combination with the use of relatively inexpensive liquid nitrogen, effects such as reduced running costs can be obtained.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing an example of a conventional cryogenic chamber, Fig. 2 is a schematic diagram showing an embodiment of the present invention, and Fig. 3 is a schematic diagram showing an example of the conventional cryostat.
■It is a detailed sectional view along the line. 9- 8- 10... Refrigerant container, 11... Refrigerant, 15...
Cooling nitrogen gas circulation path, 16... Cooling liquid nitrogen storage section, 17... Partition wall, 18... Liquid nitrogen, 19
...Vent, 22...Fan. Applicant Hiroshi Hoshino Agent Patent Attorney Yutaka 1) Hisashi Take (and 1 other person) -10-

Claims (1)

[Claims] A circulation path for circulating cooling nitrogen gas is formed around the entire outer circumferential side of the refrigerant container containing the refrigerant, and
Further, a cooling liquid nitrogen storage section is formed on the outer circumferential side of the circulation path, and these circulation paths and the cooling liquid nitrogen storage section are communicated with each other, and cooling nitrogen gas is supplied to the refrigerant container in the circulation path. A cooling cryogenic tank characterized by being provided with an air blower which causes the refrigerant to flow in the circumferential direction and whose flow rate can be adjusted according to the temperature of the refrigerant.