JPH0133749B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an indirect cooling type low temperature constant temperature bath.

As shown in Fig. 1, the conventional constant temperature bath is equipped with a refrigerant tank c in a cold source tank a via a helium gas tank b, and cools the refrigerant (such as Freon 13) by indirect cooling with helium gas. In the figure, d indicates a gas bag that supplies the refrigerant to the refrigerant tank c through the supply path e, f indicates a vacuum pump, and g indicates a helium gas cylinder.

That is, the constant temperature bath having the above configuration includes radiation from the refrigerant tank c to the cold source tank a, free particle movement of helium gas,
Since heat exchange is performed by natural convection, there is a problem in that it takes a long time to liquefy the refrigerant.

If the refrigeration power is unnecessarily increased in an attempt to increase the liquefaction rate of the refrigerant, the temperature stability will deteriorate and the consumption of the cold heat source (liquid nitrogen, etc.) will increase.

Therefore, as a result of studies in view of the above-mentioned conventional circumstances, the present invention increases the refrigeration power only when the refrigerant is liquefied, and effectively recovers the cold heat during liquefaction, thereby reducing the consumption of the cold heat source compared to the conventional example. It is an object of the present invention to provide a new indirect cooling type low temperature constant temperature bath which can reduce the temperature and perform stable cooling.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A detailed explanation will be given below based on the drawings showing specific examples of implementation of the present invention.

As shown in FIG. 2, a refrigerant tank 3 is installed inside a heat-insulated cold source tank 1 via a helium gas tank 2, and a vacuum pump 4 and a helium gas cylinder 5 are installed in the helium gas tank 2. This makes it possible to supply helium gas.

In order to enable forced circulation of the helium gas in the helium gas tank 2 through the cold source tank 1, a forced circulation path 6 with end ports connected to the upper and lower parts of the helium gas tank 2 is provided. A circulation pump P is installed in the passage 6, and
Heat exchangers 10 and 11 are respectively disposed between a refrigerant supply path 8 that supplies refrigerant from the gas bag 7 to the refrigerant tank 3 and a cold source gas discharge path 9 from the cold source tank 1. Helium gas is transferred to heat exchanger 1.
0-Circulation pump P-Heat exchanger 11-Cold heat source tank 1-
A forced circulation path 6 is configured to circulate the helium gas tank 2 in this order.

Here, the helium gas that is forced to be circulated is pre-cooled more effectively by the cold heat source.
It is preferable to dispose a heat exchanger 12 in the cold heat source tank 1 of the forced circulation path 6, and further transfer the refrigerant to the refrigerant layer 3.
A pump is installed in the middle of the supply path 8 to forcibly supply the
P′ may also be provided.

Further, as the heat exchangers 10 and 11, as illustrated in FIG. 3, it is preferable to use a tube facing type in which tubes 13 and 14 of different diameters are inserted and arranged, and the length thereof is The temperatures of the refrigerant gas and helium gas in the heat exchanger 10 and the temperatures of the helium gas and the cold source gas in the heat exchanger 11 are set in advance so as to be equal to each other.

In the above configuration, when the circulation pump P is driven and rotated, the helium gas in the helium gas tank 2 is transferred from the heat exchanger 10 to the pump P to the heat exchanger 1 as described above.
1 - Cold heat source tank 1 - Helium gas tank 2 are circulated through the forced circulation path 6 in this order.

As a result, due to the circulation operation, the helium gas that has passed through the cold source tank 1 is introduced into the helium gas tank 2, so this cooled helium gas cools the refrigerant in the refrigerant tank 3, and then heat is generated. In the exchanger 10, the refrigerant being supplied to the refrigerant tank 3 can be pre-cooled, so that the helium gas returns to room temperature and is introduced into the pump P. By recovering the cold heat of the gas, the pump P is protected from freezing.

Further, the cold source gas generated by heat exchange with helium gas in the cold source tank 1 is discharged from the cold source exhaust path 9, but at this time, the helium gas is precooled in the heat exchanger 11, so the pump The helium gas temperature at the outlet side of P (about room temperature) is exhausted.

If the pump P is stopped at this point, it can be handled as if it were a conventional pump.

As explained above, according to the indirect cooling type low temperature constant temperature bath according to the present invention, the refrigerant supplied to the refrigerant tank 3 is precooled by forcibly circulating helium gas, and the helium gas is This type of helium gas is cooled by a cold source, and the helium gas is pre-cooled in the heat exchanger 11 by the cold source gas generated by the heat exchange at this time, and the cold heat is recovered. The cooling power during liquefaction of the refrigerant can be dramatically increased without impairing the characteristics of the thermostatic chamber. Not only can the liquefaction be carried out in a short time, but also the cold heat source gas consumption during liquefaction can be reduced by recovering the cold heat of the cold heat source gas. The amount can be significantly reduced compared to the conventional example, and the operation of the pump P will not be hindered.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a conventional indirect cooling type low-temperature constant temperature bath, FIG. 2 is a schematic cross-sectional view of an indirect cooling type low-temperature constant temperature bath according to the present invention, and FIG. 3 is a schematic cross-sectional view of a heat exchanger in the same temperature bath. It is a perspective view showing an example. 1...Cold heat source tank, 2...Helium gas tank, 3...
... Refrigerant layer, 6... Forced circulation path, 8... Refrigerant supply path, 9... Cold source gas discharge path, 10, 11... Heat exchanger, P... Pump.

Claims (1)

[Claims] 1 A forced circulation path in which a refrigerant tank is installed in a cold heat source tank via a helium gas tank, in which helium gas in the helium gas tank is circulated by a pump to the helium gas tank through the cold heat source in the cold heat source tank. In the circulation path, a heat exchanger for exchanging heat with the refrigerant supplied to the refrigerant tank is provided at the front stage of the pump, and a cold heat source in the cold heat source tank is provided at the rear stage of the pump, which is generated by heat exchange with the helium gas. An indirect cooling type low-temperature constant temperature bath characterized by being provided with a heat exchanger for exchanging heat with a cold heat source gas.