JPS63220048A - Cryogenic refrigerator - 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 (Field of Industrial Application) The present invention relates to measures for improving the operability of temperature control in cryogenic refrigeration equipment using helium or the like.

(Prior Art) Conventionally, cryogenic refrigeration equipment has been developed, for example, as disclosed in U.S. Pat.
As disclosed in Japanese Patent No. 223540, a refrigerant gas such as helium is Joule-Thomson expanded using a J-T valve and supplied to a cooler, and the cooler generates extremely low temperatures by exchanging heat. well known.

(Problem to be Solved by the Invention) However, in the above-mentioned conventional system, when the cooler cools down to the target temperature, a heating heater is used in conjunction with the heater to raise the temperature for the purpose of temperature adjustment, etc. When trying to raise the temperature, it is necessary to adjust both the calorific value of the temperature raising heater and the opening degree of the J-T valve. Since it is necessary to quickly adjust the refrigerant flow rate to changes in the temperature of the cooler due to heating by the warming heater, it is necessary to adjust the input of the heating heater and the J-■ valve at the same time. It lacks operability.

To solve this problem, the first object of the present invention is to automatically adjust the refrigerant flow rate so that the refrigerant flow rate to the cooler decreases as the temperature of the cooler increases, thereby opening the J-T valve. To easily adjust temperature by eliminating the need for temperature adjustment.

On the other hand, if the refrigerant flow rate to the cooler is low during cool-down of the cooler or during temperature control,
A problem arises in that the cooling time increases. From this, the second object of the present invention, in addition to the first object, is to prevent an increase in the cooling time by taking measures to prevent a decrease in the flow rate of refrigerant to the cooler when the temperature of the cooler decreases. The purpose is to prevent it.

(Means for Solving the Problems) In order to achieve the above-mentioned first object, the solving means of the first invention is as shown in FIG. (10), a cooler (11) that generates an extremely low temperature in the controlled object (17) using Joule-Thomson expanded refrigerant in the cough J-T valve (10), and a heating means (11) that heats the controlled object (17). A cryogenic refrigeration system equipped with H) is assumed.

A cooler (11) is connected upstream and downstream of the cooler (11).
The structure is such that a bypass pipe (13) is provided to bypass and communicate with each other.

Further, in order to achieve the object of the second invention, the solution means of the second invention includes a J-T valve (10) for Joule-Thomson expansion of a gas refrigerant such as helium, as shown in FIG. - A cooler (11) that generates a cryogenic temperature in the controlled object (17) using the Joule-Thomson expanded refrigerant in the T valve (10).
), and heating means (H) for heating the controlled object (17).
This assumes a cryogenic refrigeration system equipped with

A cooler (11) is connected upstream and downstream of the cooler (11).
A bypass pipe (13) is provided to bypass and communicate with the refrigerant, and the bypass pipe (13) is provided with a flow control valve (14) for adjusting the bypass amount of the refrigerant.

(Function) With the above configuration, in the first invention, the helium gas refrigerant is supplied to the J-T valve (10
), the controlled object (17) becomes a cryogenic state due to heat exchange in the cooler (11). And this controlled object (
17) to keep the temperature constant, the heating means (H)
When the temperature of the controlled object (17) is raised by adjusting the output of the cooler (11), the refrigerant temperature of the cooler (11) increases accordingly, and the refrigerating capacity per unit weight of the cooler (11) increases rapidly. At that time, the fluid resistance of the refrigerant increases on the cooler (11) side due to the rise in refrigerant temperature, so the refrigerant flow m toward the bypass pipe (13) increases, and the refrigerant flow rate toward the cooler (11) increases. This reduces the effect of increasing the refrigerating capacity per unit weight, thereby adjusting the refrigerating capacity of the cooler (11) to an appropriate range. That is, J-T valve (10
), the overall refrigerant flow rate and refrigerant temperature are kept almost constant, so there is no need to change the opening degree of the J-T valve (10), and therefore only the heating output of the heating means (1) can be adjusted. Accordingly, the temperature of the controlled object can be controlled to be constant, and the operation can be simplified.

Further, in the second invention of the present application, the operation when performing constant temperature control of the controlled object (17) is the same as that of the first invention. In addition, during cool-down of the refrigeration system, the flow rate of refrigerant on the bypass pipe (13) side is adjusted to decrease by operating the flow control valve (14).
A sufficiently large flow rate of refrigerant on the side is ensured. Therefore, the refrigerating capacity of the cooler (11) can be maintained at a sufficiently high level, and an increase in the time required to lower the temperature of the controlled object (17) can be effectively prevented.

(Embodiments of the first invention) Hereinafter, embodiments of the first invention will be described based on FIGS. 1 and 2.

Fig. 1 shows the refrigerant system of the main part of the helium refrigeration system according to the embodiment of the first invention, and (1) is for holding the inside in a vacuum state and attaching test pieces etc. to perform various cryogenic tests. (2) is a J-T circuit unit whose main part is incorporated in the vacuum chamber (1), (3) is the vacuum chamber (
1) is a pre-cooling refrigerator installed.

(5) in the main part incorporated in the vacuum chamber (1) of the J-T circuit unit (2).

(6) and (7) are the first, second and third stages, respectively, which sequentially perform heat exchange between the high-pressure gas of the helium gas refrigerant compressed by compression l1l (not shown) and the low-pressure gas returning to the compression chamber. Third
J-T heat exchangers, <8) and (9) are respectively No. 1. a second precooler, the first and second precoolers (8), (9);
is cooled by the pre-cooling refrigerator (3). Heat exchange is performed between the second heat stage tanks (15) and (16) and the gas refrigerant on the outward path. Further, (10) is a J-T valve that causes Joule-Thomson expansion of the helium gas refrigerant from the third J-T heat exchanger (7), and (11) is a J-T valve that expands the helium gas refrigerant from the third J-T heat exchanger (7).
The cooler (11) performs a cooling effect using the Joule-Thompson expanded refrigerant using the valve (10), and the cooler (11) performs heat exchange between the Joule-Thompson expanded refrigerant and the third heat station (17) as a controlled object. This is what we do. Each of the above-mentioned devices (5) to (11) is connected to the refrigerant pipe (1
2) are connected so that refrigerant can flow, thereby forming a refrigerant circuit.

Furthermore, a supply pipe (12a>) that supplies refrigerant from the J-T valve (10) to the cooler (11), and a return pipe that returns refrigerant from the cooler (11) to the third J-T heat exchanger (7). (12b
) is connected to the cooler (11
) is bypassed and a part of the refrigerant supplied to the cooler (11
) so that it flows downstream.

Further, the third heat station (17) is connected in a thermally conductive manner to a sample mounting part (not shown) for mounting a test piece etc. for performing a cryogenic test, and a cooler (11) is installed below the third heat station (17). The third heat station (
3rd heat station (17) when controlling the temperature of
A temperature increasing heater (1) is arranged as a heating means for heating the (controlled object).

In FIG. 1, (18) is a heat conductive rod that connects the second and third heat stations (16) and (17) in a heat conductive manner, and (19) is the second heat station. 3rd J-T heat exchanger (6), (7), 2nd precooler (9), 2nd. Third
Heat station (16), (17), J-T valve (1
0), a heat shield that radiation-seals the entire cooler (11), heater (H), and bypass pipe (13), (2)
0) is a handle for manually opening and closing the J-T valve (10).

Next, to explain the operation of the above embodiment, when the refrigeration system is operated, the helium gas refrigerant sent from the pressure aa is
It is cooled by heat exchange with the return refrigerant in the heat exchanger (5), and then precooled in the first precooler (8), and then the second J-T heat exchanger (6) and the second precooler ( 9), 3rd J-
In the T heat exchanger (7), the heat exchanger (7) receives a similar cooling effect and is sequentially cooled down to near cryogenic temperatures. And J-T valve (
At 1o), the third heat station (17) is brought to a cryogenic temperature due to the Joule-Thomson expansion action and is cooled to a cryogenic temperature by heat exchange in the cooler (11). After the third heat station (17) is cooled down, the output of the heater (1-1) is adjusted and the cooling capacity of the cooler (11) is automatically adjusted accordingly. 17) temperature is maintained at a predetermined value. The principle of adjustment will be explained below with reference to FIGS. 2 to 4.

Figure 2 shows the J-T valve (1) of the above J-T circuit unit (2).
0) Details of the nearby refrigerant circuit, (a) is a point between the second heat station (9) and the third J-T heat exchanger (7), and (b) is the point between the third J-T heat exchanger (7). Vessel (7) and J-
One point between the T valve (10), (c) is the J-T valve (10)
(d) is a point between the junction of the cooler (11) and the bypass pipe (13), and (e) is the junction of the bypass pipe (13). Point and 3rd J-
One point between the T heat exchanger (7), (f) is the point between the third J-T heat exchanger (7) and the second J-T heat exchanger (6) on the return trip
It is a point between.

Then, if the refrigerant flow rate to the cooler (11) (in terms of weight, the same applies hereinafter) and the refrigerant flow rate to the G1 bypass pipe (13) are G', the total refrigerant flow rate Go (see Figure 2) is as follows (
1) Expression % Expression % (11) When the third heat station (17) is heated by the heater (H), the cooler (11) cools the refrigerant to increase the refrigerant temperature. The pressure loss increases and the refrigerant flow rate G decreases.

Therefore, the refrigerant flow rate G (point (
d)) and the third heat station (17
When the temperature of Point (d
) decreases as the refrigerant temperature Td increases.

Further, the relationship between enthalpy and pressure at each point (a) to (f) of the refrigerant circuit is as shown at each point (a) to (1') on the Mollier diagram in FIG. The refrigerating capacity per unit weight of the refrigerant in the cooler (11) in the standard state is the enthalpy hO at point (e).
and the enthalpy hc at point (C) (enthalpy change) expressed as ΔhA. In other words, the following equation (2), Δ
hA=h8-hc (2) holds true.Similarly, by heating the heater (H>), the above point (d)
When the cooling tlIc temperature Td increases, the refrigerating capacity (enthalpy change) Δh per unit of refrigerant of the cooler (11) is expressed by the following formula (3), Δh=hd −hc
[3], and the above ΔhA
(see FIG. 3), the enthalpy change ratio Δh/ΔhA between Δh and ΔhA increases very rapidly as the refrigerant temperature Td increases (see FIG. 4).

The refrigerating capacity of the cooler (11) is determined by the product of the refrigerant flow IG and the refrigerating capacity Δh per unit weight.
Then, the refrigerating capacity ratio Q / Q A of both increases as the temperature rises, but the rate of increase is moderated by the decrease in the flow rate of refrigerant to the cooler (11), and the refrigerating capacity ratio per unit weight (enthalpy) increases. (change ratio) is much slower than the rate of increase of Δh/Δh^ (see Fig. 4).

As derived from the above relationship between the refrigerant flow rate, each enthal, and the refrigerating capacity, the third
In order to control the temperature of the heat station (17) to a certain constant value Td, find the refrigerating capacity ratio Q / Q A corresponding to the refrigerant temperature Td from the characteristic diagram in FIG. The ratio between the refrigerant flow rate GA of 11) and the refrigerant flow ff1GA' of the bypass pipe (13) is determined as follows (
4) Formula, GA/GA' = 1/((Q/QA)-1)
(41). In other words, when the above equation (4) is satisfied, the enthalpy he and the refrigerant temperature at the point (e) after the convergence of the cooler (11) side and the bypass pipe (13) side Since Te remains unchanged, J-
The refrigerant temperature in the cooler (11) can be raised to Td while the opening degree of the T-valve (10) remains constant.

In other words, the temperature of the third heat station (17) can be controlled to a certain level at the target temperature Td simply by adjusting the heating output of the heater (H).

In the conventional system, since there is no ability to automatically adjust the flow rate of refrigerant to the cooler (11) through the bypass pipe (13), as shown in the characteristic diagram of Fig. 3, the amount per unit weight when the temperature rises is Since the refrigerating capacity ratio Q/QA between the refrigerating capacity Q and the refrigerating capacity QA per unit time in the standard state increases rapidly as the refrigerant temperature Td increases, in reality, the J-T valve (10) It is very difficult to maintain a constant temperature by controlling the opening of the valve. In contrast, in the example of the present invention, since the bypass pipe (13) is provided between the supply pipe (12a) and the return pipe (12b), even when the temperature rises due to heating by the heater (H>), the J-T valve (1
There is no need to change the opening degree of the third heat station (17), and the temperature of the third heat station (17) can be maintained at a constant temperature with a simple operation.

In addition, in this embodiment, since the refrigerant flow rate of the cooler (11) is bypassed by the bypass pipe (13), the cooling down time of the third heat station (17) may increase when cooling down the third heat station (17). . However, the cryogenic refrigeration system of this embodiment is suitable for tests that require constant temperature control over a long period of time in a cryogenic state, such as measuring the characteristics of a superconductor material near its transition temperature. It is highly effective in various tests.

(Example of the second invention) Next, an embodiment of the second invention will be explained based on FIG.

FIG. 5 shows a refrigerant system of a helium refrigeration system according to an embodiment of the second invention, and most of its configuration is the same as that of the embodiment of the first invention shown in FIG. The same parts as in FIG. 1 will be given the same reference numerals and the explanation will be omitted, and only the different parts will be explained.

In FIG. 5, the supply pipe (12a) and return pipe <12b) of the cooler (11) are connected by a bypass pipe (13) so that the refrigerant can flow therebetween. Furthermore, the bypass pipe (13) is opened and closed by an electric shintan to cause the refrigerant flow f.
Electromagnetic on-off valve (14) as a flow control valve to adjust aG'
) is provided.

Therefore, in this case, it is possible to control the temperature of the third heat station (17) to be constant only by adjusting the heating by the heater (H), and when cooling down the third heat station (17), the electromagnetic on-off valve ( 14
), the temperature can be lowered quickly.

That is, in the embodiment of the first invention, the third heat station (17) is also bypassed during cool-down. ! Since there is a bypass flow of refrigerant to the cooler (13), the refrigerating capacity of the cooler (11) may be reduced and it may take a longer time to lower the temperature, but in this example, the electromagnetic By closing the on-off valve (14), the refrigerating capacity of the cooler (11) can be maintained sufficiently large, and therefore, an increase in temperature drop time can be effectively prevented.

Therefore, the example of the present invention is particularly effective for characteristic tests in a wide temperature range of about 4 to 300 degrees, for example, measurement of temperature characteristics of cryogenic temperature sensors.

In the embodiment of the second invention, an electromagnetic on-off valve (14) was used as the flow control valve, but the flow control valve of the present invention is not limited to the above embodiment, and a proportional control valve or the like may be used. May be used.

Furthermore, in the embodiments of the first and second inventions described above, cooling,
Although an example using helium gas as the medium has been described, the refrigerant used in the present invention is not limited to helium, and it goes without saying that other refrigerants such as hydrogen gas can be used, for example.

(Effects of the Invention) As explained above, according to the cryogenic refrigeration system of the present invention, as an effect of the first invention, a bypass bypassing the cooler is provided between the refrigerant supply pipe and the return pipe of the cooler. Since the tube is installed, when controlling the temperature of the controlled object using the cooler,
The refrigerating capacity of the cooler is automatically adjusted to an appropriate range according to the temperature rise caused by the heating means, and the temperature of the controlled object can be controlled to a constant level simply by adjusting the heating output of the heating means, simplifying operation. can.

Furthermore, as an effect of the second invention, since a flow control valve for controlling the refrigerant flow rate is provided in the bypass pipe, similar to the first invention, the control operation can be simplified when controlling the temperature of the controlled object to be constant. In addition, during cool-down of the controlled object, the refrigerant flow rate in the bypass pipe can be reduced to fully utilize the refrigerating capacity of the cooler, and an increase in temperature drop time can be effectively prevented.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the first invention of the present application,
Figure 1 is the refrigerant system diagram, Figure 2 is an enlarged view of the refrigerant system near the J-■ valve, Figure 3 is the Morinil diagram, and Figure 4 is the refrigerant flow rate as the refrigerant temperature rises, and the refrigeration capacity per unit weight. and a characteristic diagram showing changes in the overall refrigerating capacity of the cooler. Moreover, FIG. 5 is a refrigerant system diagram of a refrigeration system according to an embodiment of the second invention. (10)...J-T valve, (11)...Cooler, (1
3)...Bypass pipe, (14)...Solenoid on-off valve (flow control valve) (17)...Third heat station (controlled object), (H)...Heater (heating means). Patent applicant Daikin Industries, Ltd. --- Agent Patent attorney 1)
HiroFigure 5Figure 2Figure 1

Claims (2)

[Claims] (1) A J-T valve (10) that Joule-Thomson-expands a refrigerant gas such as helium, and a cooler that generates a cryogenic temperature in a controlled object (17) using the Joule-Thomson-expanded refrigerant in the J-T valve (10). (11) and the above controlled object (17
) in a cryogenic refrigeration system equipped with a heating means (H) for heating the cooler (11), upstream and downstream of the cooler (11).
) is provided with a bypass pipe (13) that bypasses and communicates with the cryogenic refrigerator. (2) A J-T valve (10) that Joule-Thomson-expands a gas refrigerant such as helium, and a cooler (17) that generates a cryogenic temperature in a controlled object (17) using the Joule-Thomson-expanded refrigerant in the J-T valve (10). 11) and the above controlled object (17)
In a cryogenic refrigeration system equipped with a heating means (H) for heating a cooler (11), upstream and downstream of the cooler (11)
A cryogenic refrigeration apparatus characterized in that a bypass pipe (13) is provided to bypass and communicate with the refrigerant, and the bypass pipe (13) is provided with a flow control valve (14) for adjusting the bypass amount of refrigerant.