JPH0428256A - Boiling-cooling device provided with air leak detection device - Google Patents

Abstract

PURPOSE:To enable a cooling device to execute a cooling operation high in safety by a method wherein a mixed coolant composed of at least two or more main components is used to cool down a large current element, and the rise of pressure inside the hermetically closed circuit is detected. CONSTITUTION:A cooling device is charged with mixed coolant 3 of 35% by weight of ethylene glycol aqueous solution composed of water and ethylene glycol which are different from each other in boiling point. A large current element releases heat when it is excited, and the coolant 3 evaporated by boiling in a cooling fin 1 is made to move up to a condenser 6 passing through a vapor phase tube 5 via a heat transfer tube 9 and a liquid reservoir 4. The coolant 3 liquidized in the condenser 6 is made to return to the liquid reservoir 4 passing through a liquid phase tube 6 and then sent to the cooling fin 1. When air penetrates into a hermetically closed circuit, air bubbles are generated making dissolved vapor serve as nucleuses, the grown bubbles reach the interface of the coolant 3 and burst making a sound. The sound made at the burst of bubbles is detected by a sound pressure detector 8 provided with a microphone. By this setup, even if air leaks, air leak can be detected at an easily stage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a boiling cooling device with an airtight leak detection device used for cooling a large current element.

[Prior art] The boiling cooling method has been gaining popularity in recent years because it is easier to cool large current devices than the convection cooling method and allows for natural circulation. The evaporative cooling device used in this study has come into use.

This evaporative cooling device has an airtight structure with a closed circuit, in which a fluorocarbon gas such as fluorocarbon R-113 is sealed as a refrigerant. This coolant cools large current devices, such as thyristor devices. In this way, since the evaporative cooling system has a structure in which a refrigerant, such as Freon R-113, is sealed in a closed circuit, airtight leaks caused by corrosion etc. can be detected and dealt with at an early stage during maintenance of the evaporative cooling system. This is an important measure to prevent accidents. For this reason, conventional evaporative cooling devices use temperature detectors to detect airtight leaks in closed circuits. When an airtight leak occurs in a closed container, this temperature detector detects an increase in the fluorocarbon temperature due to a decrease in the cooling capacity of the condenser, thereby detecting the occurrence of an airtight leak.

[Problem to be solved by the invention] As mentioned above, conventional boiling cooling devices use fluorocarbon gas as a refrigerant, which has become a problem in recent years as it destroys the ozone layer. High quality refrigerants are required.

SUMMARY OF THE INVENTION An object of the present invention is to provide an evaporative cooling device with an airtight leak detection device that uses a highly safe refrigerant and can detect airtight leakage at an early stage even if it occurs.

[Means for Solving the Problems] A boiling cooling device with an airtight leak detection device according to the present invention includes a liquid reservoir containing a refrigerant made of at least two or more components;
a condenser that communicates with the liquid reservoir through a liquid phase pipe and a gas phase pipe and forms a circulation circuit with the liquid reservoir; a cooling fin that communicates with the liquid reservoir and is equipped with a large current element that is a medium to be cooled; and internal pressure detection means provided on the outer wall surface of the liquid reservoir.

[Function] The evaporative cooling device with an airtight leak detection device according to the present invention cools a large current element using a refrigerant having at least two or more main components, for example, a mixed refrigerant of water and ethylene glycol.
When an airtight leak occurs, the airtight leak is detected by an internal pressure detection means that detects an increase in pressure inside the sealed circuit, such as a detection means using a sound pressure detector or a strain amount detector.

[Example] Hereinafter, the first embodiment of the evaporative cooling device with an airtight leak detection device of the present invention will be described.
An example of this will be described with reference to the drawings. FIG. 1 is a schematic diagram of a boiling cooling device with an airtight leak detection device according to a first embodiment of the present invention. In the figure, the boiling cooling device of the first embodiment includes a liquid reservoir 4, a condenser 6, a plurality of cooling fins 1, and a gas phase pipe 5 that connects the liquid reservoir 4 and the condenser 6 to form a circulation circuit. It is equipped with a phase pipe 7. Further, the plurality of cooling fins 1 and the liquid reservoir 4 are communicated with each other through heat transport pipes 9 provided in a number corresponding to the plurality of cooling fins 1. Therefore, this boiling cooling device consists of a first circulation system composed of a liquid reservoir 4, a gas phase pipe 5, a condenser 6, and a liquid phase pipe 7, and a liquid reservoir 4, a heat transport pipe 9, and a cooling fin 1. It has a second circulatory system. Inside the first and second circulation systems described above, a 35 wt% ethylene glycol aqueous solution, which is a mixture of water and ethylene glycol (65:35) having different boiling points, is sealed as the refrigerant 3, for example.

As shown in FIG. 1, the boiling cooling device configured as described above is provided with a sound pressure detector 8 on the outer wall surface of the container of the liquid reservoir 4. The sound pressure detector 8 detects the sound generated inside the container, and is, for example, a sound pressure needle using a microphone. This sound pressure needle preferably has a frequency measurement range of several tens to several hundred Ilz. The sound pressure level signal detected by the sound pressure needle is transmitted to a monitoring device (not shown) provided outside the device via a signal line 8a.

The operation of the evaporative cooling device with an airtight leakage detection device according to the first embodiment configured as described above will be described next.

Between the plurality of cooling fins 1, a plurality of large current elements 2, such as silice devices, which are the medium to be cooled, are installed. When the large current element 2 is excited and generates heat, the refrigerant 3 boiled and vaporized inside the cooling fin 1 passes through the heat transport pipe 9 and the liquid retainer 4, passes through the gas phase pipe 5, and moves upward to the condensing pipe 6. The refrigerant 3 liquefied in the condenser 6 passes through the liquid phase pipe 6, returns to the reservoir 4, and is sent to the cooling fins 1 via the return pipe 9a inside the heat transport pipe 9.

In this embodiment, the ethylene glycol aqueous solution that is the refrigerant 3 is sufficiently degassed, so that bubbles are unlikely to be generated under normal cooling operating conditions. This is because there is no dissolved gas such as 02 or N2 in the degassed refrigerant, so that bubbles with this dissolved gas as a nucleus are not generated.

Next, a case will be described in which an airtight leak occurs inside the sealed circulation circuit in the above-mentioned evaporative cooling device with an airtight leak detection device in a normal cooling operation state. For example, the saturated vapor pressure of a 35 wt % aqueous solution of ethylene glycol used as the refrigerant 3 is sufficiently lower than atmospheric pressure. Therefore, the internal pressure of the closed circuit containing the degassed ethylene glycol aqueous solution is lower than atmospheric pressure under normal operating conditions. Therefore, if an airtight leak occurs in a sealed circuit due to corrosion or the like, air outside the sealed circuit will enter the sealed circuit, increasing the internal pressure. If air gets mixed into the sealed circuit in this way, the air will be dissolved in the ethylene glycol aqueous solution, creating a state where bubbles are likely to be generated. When heat is applied to the refrigerant in this state, bubbles are generated in the liquid using the dissolved gas as nuclei.

The generated bubbles grow and reach the interface of the refrigerant 3, deform the interface, emit a sound, and disappear. This sound when the bubble disappears is detected by the sound pressure detector 8 using the aforementioned microphone. This detected sound when bubbles disappear is transmitted as an electrical signal to a known monitoring device (not shown) via the signal line 8a.
A leak in the sealed circuit is detected. The monitoring device detects the magnitude of the sound pressure level when bubbles disappear and the frequency of occurrence, and calculates the internal pressure in the sealed circuit based on pre-measured data to detect the magnitude of airtight leakage.

Note that by detecting airtight leakage using the sound pressure detector 8 during a time period when there is less noise before and after the cooling operation, it becomes possible to detect the sound when a small bubble disappears due to a slow airtight leakage.

Next, the second part of the evaporative cooling device with an airtight leak detection device of the present invention will be described.
An example of this will be described with reference to the drawings. FIG. 2 is a schematic diagram of a boiling cooling device with an airtight leak detection device according to a second embodiment of the present invention. In the figures, the same components as those in the first embodiment described above are given the same reference numerals, and the explanation of the duplicated components will be omitted. In the figure, a strain amount detector 18 is provided on the outer wall surface of the upper part of the container of the liquid retainer 4. This strain amount detector 18 detects the shape displacement of the wall surface due to a change in the internal pressure of the container. This strain amount detector 18 uses, for example, a strain gauge and converts the shape displacement into an electric signal to
8a to a monitoring device (not shown) provided outside the device.

The boiling cooling device with an airtight leak detection device of the second embodiment configured as described above operates in the same manner as the first embodiment described above in a normal cooling operation state.

Next, a case will be described in which an airtight leak occurs inside the closed circuit in the apparatus of the second embodiment in this normal cooling operation state. The saturated vapor pressure of, for example, a 35 wt % aqueous ethylene glycol solution used as the refrigerant 3 is sufficiently lower than atmospheric pressure. Therefore, the internal pressure of the closed circuit in which the degassed ethylene glycol aqueous solution is enclosed is lower than atmospheric pressure under normal cooling operating conditions. Therefore, the wall shape of the container of the liquid retainer 4 is curved inward. Therefore, if an airtight leak occurs in a sealed circuit due to corrosion or the like, air from outside the sealed circuit will enter the sealed circuit, increasing the internal pressure. As a result, the shape of the container wall surface of the liquid reservoir 4 is displaced outward. In this way, when air gets mixed into the sealed circuit, the shape of the container wall of the liquid retainer 4 changes, and this shape change is converted into an electrical signal by the strain amount detector 18, and sent to the monitoring device via the signal line 18a. (not shown). The monitoring device calculates the internal pressure in the sealed circuit based on this electrical signal and detects this airtight leak. Note that the degree of airtight leakage is detected from the amount of displacement of the internal pressure per unit time.

[Effects of the Invention] As described above, according to the present invention, a mixture of at least two or more substances as main components, such as an aqueous ethylene glycol solution, is used as a refrigerant as a substitute for fluorocarbon gas, and
Providing the internal pressure detection means has the effect of providing a device that is highly safe and can detect airtight leaks at an early stage even if they occur.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a boiling cooling device with an airtight leak detection device according to a first embodiment of the present invention, and FIG.
is a cooling fin, 3 is a refrigerant, 4 is a liquid retainer, 5 is a gas phase pipe, 6
is a condenser, 7 is a liquid phase pipe, and 8 and 18 are internal pressure detection means. In addition, the same symbols in the figures indicate the same or equivalent parts.

Claims (3)

[Claims] (1) A liquid reservoir containing a refrigerant consisting of at least two or more components; a condenser communicating with the liquid reservoir through a liquid phase pipe and a gas phase pipe and forming a circulation circuit with the liquid reservoir; communicating with the liquid reservoir; 1. A boiling cooling device with an airtight leak detection device, comprising: a cooling fin on which a large current element, which is a medium to be cooled, is attached; and an internal pressure detection means provided on the outer wall surface of the liquid reservoir. (2) The boiling cooling device with an airtight leak detection device according to claim (1), wherein the internal pressure detection means is a sound pressure detector. (3) The boiling cooling device with an airtight leak detection device according to claim (1), wherein the internal pressure detection means is a strain amount detector.