JPH0631702B2 - Two-phase fluid loop - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a two-phase fluid loop for heat transfer by a thermodynamic cycle involving phase changes of evaporation and condensation.

[Technical background of the invention and its problems]

As a heat transport method for space stations and the like, a liquid loop is promising because of the requirement for its large heat transport capacity.

However, in the single-phase fluid loop, heat is transported by utilizing sensible heat, so a large amount of working fluid must be circulated in order to keep the temperature of the heating section within a narrow temperature range. However, it is not practical in terms of weight and pump power.

Therefore, when it is necessary to transport a large amount of heat with a small amount of power and to keep the temperature of the heating part within a narrow temperature range, such as a space station, heat is transported using latent heat due to the phase change of the working fluid. Two-phase fluid loops are considered advantageous.

In other words, since the two-phase fluid loop uses latent heat, it requires only a small amount of working fluid to be circulated, and therefore has the advantage that the pipes and pumps can be made smaller and lighter, and has a small circulation driving force, which is sufficiently practical. It is a method. In this two-phase liquid loop, the circulating fluid is sent in a liquid phase to a heat generating portion such as an electronic device, where it absorbs heat and changes into a vapor phase. This vapor phase is sent to the heat radiating portion, where it radiates heat and is returned to the liquid phase again. As a method of driving such a two-phase working fluid, for example, there is a method using a mechanical pump, a method using a capillary pump, or the like.

And, as a two-phase fluid loop using a conventional mechanical pump, there is one as shown in FIG. 5, for example. In other words, this two-phase fluid loop has a condenser part 1 as a heat dissipation part.
01, an evaporator 103 as a heat absorbing portion, a melical pump 105 for driving a working fluid, a regulating valve 107, and the like. Therefore, the evaporator 1 as the heat absorbing section
The vapor that has absorbed and evaporated from the electronic device or the like in 03 is transported to the condenser 101 as a heat radiating portion via the pipe, and releases heat to be condensed therein. The condensed liquid is driven by the mechanical pump 105 to be refluxed.

The two-phase fluid loop configured in this way has the ability to transport a large amount of heat to a long distance with a small pump, and it can be actively controlled by the number of rotations of the pump and the operation of a regulating valve. It has the feature that it can respond to fluctuations in heat quantity. However, in a flow in which gas-liquid two phases coexist, various flow instabilities or vibration phenomena are likely to occur. For example, in an evaporation tube, various flow instability phenomena are expected in addition to the runaway instability in which the flow rate becomes unstable in the region where the pressure loss with respect to the increase in flow rate is negative. Further, also in the condensing part, for example, in the part where the steam flows into the supercooled water, it is expected that vibration accompanying the submerged condensation of the steam will occur. Thus, it is extremely difficult to perform stable control on the basically unstable two-phase fluid loop. Furthermore, since the characteristics of the two-phase flow in a weightless field such as outer space are unknown, control of the two-phase fluid loop has become a difficult problem. There are also problems with cavitation of working fluid, lubrication of motors, and reliability.

Therefore, a capillary pump system, which is a two-phase fluid loop of a type that automatically compensates for the amount of vaporized liquid by a capillary force, similar to a heat pipe has been developed.

An example of this capillary pump system is shown in FIG. That is, in this system, a capillary 201a is provided in the evaporation section 201 as a heat absorption section, and the liquid of the condensation 203 as a heat dissipation section is drawn in by a capillary force.

The capillary pump configured as described above is characterized in that it requires no external pump power to drive the working fluid, and has a self-controllability that only the vaporized liquid is supplied. However, since the fluid driving force relies on the capillary force, the liquid transport capacity is small, and there is a problem that a large amount of heat or long-distance heat transport cannot be performed.

[Object of the Invention]

This invention was created in view of the above-mentioned conventional problems,
An object of the present invention is to provide a two-phase fluid loop capable of transporting a large amount of heat over a long distance and having stable control characteristics even in a weightless field such as outer space.

[Outline of Invention]

In order to achieve the above object, the present invention has a main loop that circulates a liquid-phase working fluid with a pump, and an evaporator having a capillary structure that is provided on the high-pressure side of the main loop and that is supplied with liquid from the main loop. A two-phase fluid loop was constituted by a condensing section provided on the low-pressure side of the main loop for returning liquid to the main loop and a bypass for transporting the vapor evaporated in the evaporating section to the condensing section.

〔The invention's effect〕

According to the configuration of the present invention, since the driving force of the working fluid of the main loop is given by the pump, a large amount of heat can be transported to a long distance, and the supply of the liquid evaporated in the evaporating unit can be performed by the capillary force of the evaporating unit. Since the control is performed by the self-control method, the control can be easily performed.

Further, since there is no portion where the vapor phase and the liquid phase are mixed and flowing, stable control can be performed without causing phenomena such as flow instability even in a weightless field such as outer space.

Example of Invention

An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows a schematic configuration diagram of a two-phase fluid loop. This two-phase fluid loop evaporates a working fluid in a liquid phase by absorbing heat from a condenser section 1 as a heat radiation section that radiates heat to outer space and electronic equipment. A vaporization section 3 as a heat absorption section, a main loop 5 for circulating a working fluid, and a pump 7 for providing a driving force for liquid circulation.
And a bypass 9.

The evaporation part 3 has a capillary 3a and has a capillary structure, is connected to the high pressure side 5a of the main loop 5, and the capillary 3a is in contact with the working fluid on the high pressure side 5a. The condensing unit 1 also has a capillary 1a and has a capillary structure, is connected to the low-pressure side 5b of the main loop 5, and the capillary 1a is in contact with the working fluid on the low-pressure side 5b. The evaporator 3 and the condenser 1 are connected by the bypass 9.

Next, the operation of the above embodiment will be described.

The liquid-phase working fluid in the main loop 5 is given a driving force by the pump 7 and circulates in the main loop 5.

Then, in the evaporator 3, the working fluid in the high pressure side 5a is introduced by the capillary force of the capillary 3a. The introduced working fluid as a liquid phase absorbs heat from the electronic device or the like in the evaporator 3 and evaporates. The vapor phase evaporated in the evaporator 3 is
It passes through the bypass 9 and reaches the low temperature condenser section 1. In this condenser 1, the vapor phase enters into the capillary 1a on the condenser 1 side due to the pressure difference between the bypass 9 and the low-pressure side 5a, radiatively condenses and becomes a liquid phase again, and returns from the low-pressure side 1a to the main loop 5.

In the evaporation section 3, the same amount of liquid as the evaporated liquid is taken in from the low pressure side 5a of the main loop 5 by the capillary force of the capillary 3a.

The pressure displacement of the main loop 5 and the bypass 9 at this time is
The state shown in FIG. 2 is obtained, and the above operation is confirmed.

As described above, since the driving fluid is applied to the working fluid in the main loop 5 by the pump 7, a large amount of heat can be transported to a long distance.

Further, the supply of the liquid evaporated in the evaporation unit 3 is performed in a self-controlled manner by the capillary force of the capillaries 3a.
Stable control can be easily performed.

Furthermore, since the liquid phase is circulated in the main loop 5 and the vapor phase is caused to flow through the bypass 9, there is no portion where the vapor phase and the liquid phase are mixed, so that the flow is unstable even in a weightless field such as outer space. It is possible to perform stable control without causing such phenomena.

The present invention relates to a two-phase fluid loop system, and the structures of the condenser 1 and the evaporator 3, the communication structure between the soin loop 5 and the bypass 9, and the like can be arbitrarily configured. For example, the monogroove heat pipe 11 having the cross-sectional structure shown in FIG. 3 may be used to form the structure shown in FIG. That is, the liquid flow path 13 of the mono-groove heat pipe 11 is connected to the main loop 5
It may be configured such that the vapor passage 15 having the axial group and the circumferential group forming a capillary structure is connected to the bypass 9 by connecting to the to form the condensing section 1 and the evaporating section 3.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a two-phase fluid loop according to an embodiment of the present invention, FIG. 2 is a schematic pressure distribution diagram of each portion of the fluid loop according to the configuration of FIG. 1, and FIG. 3 is a monogroove heat pipe. FIG. 4 is a schematic configuration diagram of a two-phase fluid loop using a mono-groove heat pipe, FIG. 5 is a schematic configuration diagram of a pump two-phase fluid loop according to a conventional example, and FIG. 6 is a capillary pump according to a conventional example. It is a schematic block diagram of a system. (Explanation of the symbols indicating the main parts of the drawing) 1 ... Condensing part, 3 ... Evaporating part 5 ... Main loop, 7 ... Pump 9 ... Bypass

Claims (1)

[Claims] 1. A main loop for circulating a liquid-phase working fluid by a pump, an evaporator having a capillary structure provided on the high pressure side of the main loop and supplied with liquid from the main loop, and provided on the low pressure side of the main loop. A two-phase fluid loop comprising a condensing part for returning liquid to the main loop and a bypass for transporting vapor evaporated in the evaporating part to the condensing part.