JP2000146357A - Cooling system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling system in which a plurality of heat transfer media, e.g. fuel and ram air, can be used as a heat sink for cooling a first heat transfer medium and fuel consumption of an aircraft can be reduced in operation. SOLUTION: In order to use a plurality of heat transfer media, e.g. fuel and ram air, as a heat sink for cooling a first heat transfer medium having high temperature and pressure through compression by means of a compressor 3 in a system for cooling an apparatus (heat load) having a high generation rate using a vapor cycle, a fourth heat transfer medium circulation passage 18 for cooling a first heat exchanger 1 is provided and a fourth heat transfer medium is circulated by means of a pump 19. A third heat exchanger 21 for cooling the fourth heat transfer medium with fuel and a fourth heat exchanger 22 for cooling the fourth heat transfer medium with ram air are arranged in that pipeline. Fuel is used as a heat sink when an aircraft is stopping on the ground or flying at a low speed whereas fuel and ram air are used as a heat sink when the aircraft is cruising thus realizing an operation where ram air intake causing drag on the fuselage is minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling system using a vapor cycle system for an aircraft, a ship, a vehicle or the like.

[0002]

2. Description of the Related Art Aircraft-mounted electronic devices are required to be reduced in size and weight, and are designed to be compact despite consuming a large amount of power, such as radar devices.
Heat generation part of these devices that becomes heat load (hereinafter referred to as heat load)
Cooling becomes a problem, and a cooling system is required. This type of cooling system includes adiabatic compression of refrigerant gas, cooling and liquefaction of high-temperature, high-pressure gas, adiabatic free expansion with an expansion valve to obtain a cold two-phase gas-liquid state, A vapor cycle using the latent heat of vaporization for cooling is generally used. FIG. 2 shows a configuration of a conventional cooling system.

[0003] The conventional cooling system shown in FIG. 2 is composed of three fluid flow paths of a first heat transfer medium circulation path 60, a second heat transfer medium flow path 50 and a third heat transfer medium circulation path 66. .
Heat is exchanged between the respective fluid flow paths via a heat exchanger. That is, the first heat transfer medium circulation path 60 and the second heat transfer medium flow path 50 are connected via the first heat exchanger 51 to the first heat transfer medium
The heat transfer medium circulation path 60 and the third heat transfer medium circulation path 66 exchange heat through the second heat exchanger 52. The main configuration of each of these heat transfer medium circulation paths is as follows. That is, the first heat transfer medium circulating path 60 is a circulating path of a first heat transfer medium, which is a refrigerant gas, for example, an alternative CFC gas.
A compressor 53, a control valve 56, a first heat exchanger (condenser) 51, an expansion valve 55, and a second heat exchanger (evaporator) 52, which are driven by A, are connected by a pipe constituting a circulation path. Further, a pipe line bypassing the compressor 53 is provided, and a control valve 54 is provided. In addition, a flow sensor 59 and a pressure sensor 64 are provided in an outlet pipe of the compressor 53, and a temperature sensor 57 and a pressure sensor 58 are provided in an outlet pipe of the evaporator 52. The third heat transfer medium circulation path 66 is a circulation path for a heat transfer medium, for example, an ethylene glycol mixed liquid (third heat transfer medium), and a pipe in which the pump 61, the second heat exchanger 52, and the heat load 62 form a circulation path. Connected by Further, a temperature sensor 65 is provided in a pipe at the inlet of the heat load.

Next, the operation of the conventional cooling system will be described. In the first heat transfer medium circulation path 60, the gas serving as the first heat transfer medium is adiabatically compressed by the compressor 53 driven by the motor 53A, and the high temperature and high pressure gas passes through the control valve 56 which is a three-way valve. A second heat transfer medium (for example, fuel in a fuel tank serving as a heat sink) which is guided by the condenser 51 and flows through a second heat transfer medium flow path 50 which is a flow path facing the first heat transfer medium circulation path 60 of the condenser 51; And heat is exchanged between them, and most of them are liquefied and expanded.
, And is insulated and freely expanded by the expansion valve 55, and the cold gas-liquid 2
It becomes a fluid in a phase state (gas-liquid two-phase fluid). This gas-liquid two-phase fluid is guided to the evaporator 52 and circulates through a third heat transfer medium circulation path 66 that is a flow path facing the first heat transfer medium in the evaporator 52 (for example, ethylene glycol). And the third heat transfer medium is cooled and vaporized by the latent heat of vaporization of the liquid phase. The vaporized first heat transfer medium is input to the inlet of the compressor 53, is compressed again, and circulates. In the third heat transfer medium circulation path 66, the pump 6
1, the third heat transfer medium is circulated, and the third heat transfer medium cooled by the evaporator 52 is guided to the heat load 62 to cool the heat load 62, and is returned to the inlet of the pump 61 again. Circulate.

When the temperature of the third heat transfer medium detected by the temperature sensor 65 becomes lower (higher) than the target value, the motor 5
The rotation speed of the 3A is lowered (increased) and the compressor 53
The flow rate of the first heat transfer medium in the evaporator 52 is reduced (increased) by increasing (lowering) the
Temperature control for increasing (decreasing) the temperature of the heat transfer medium is performed by the controller 63.

Further, in order to stably operate the system, the first heat transfer medium flowing into the compressor 53 in the first heat transfer medium circulation path 60 is supplied to the compressor 53 using signals from the temperature sensor 57 and the pressure sensor 58 at the compressor inlet. Complete gasification control for controlling the opening degree of the expansion valve 55 so as not to flow as it is is performed by the controller 63.

If the flow rate of the first heat transfer medium flowing into the compressor 53 falls below a certain value which depends on the ratio of the inlet pressure to the outlet pressure (compression ratio) of the compressor, surging occurs and the flow becomes unstable. Flow rate, compressor inlet pressure sensor 58, outlet pressure sensor 6
The control valve 5 is provided in a pipe that bypasses the compressor 53 so that the flow rate of the gas flowing into the compressor 53 does not become lower than a predetermined value.
The controller 63 performs compressor surging prevention control for controlling the opening degree of the compressor 4.

Further, the first compressed by the compressor 53
If the heat transfer medium is excessively cooled in the condenser 51 by the second heat transfer medium, the gas will be liquefied and the pressure will decrease too much, and the required cooling will not be obtained in the expansion valve 55. The pressure at the inlet of the valve 51 is detected by a pressure sensor 64, and the three-way valve 5 is controlled so that the pressure falls within a predetermined range.
The controller 63 also controls the maintenance of the condenser pressure for adjusting the amount of the first heat transfer medium that bypasses the condenser 51 by 6.

[0009]

The conventional cooling system is configured as described above. However, when only the fuel is circulated and used as the cooling source for the first heat transfer medium, the fuel temperature rises with time. As a result, the amount of liquefaction of the first heat transfer medium in the condenser decreases, and the cooling capacity decreases. On the other hand, if the airframe is provided with an opening to take in outside air (ram air) and use it as a cooling source for the first heat transfer medium, the ram air cannot be introduced sufficiently while the aircraft is stopped or flying at extremely low speed, so a separate fan It is necessary to provide forced air blowing means. In addition, if ram air is taken in during the cruise of the aircraft, a drag occurs that causes resistance in propulsion. Since the fuel consumption increases when a drag occurs, there is a demand for minimizing cooling by taking in outside air. The present invention has been made in view of such circumstances, and a plurality of heat transfer media such as fuel and ram air can be used as a heat sink for cooling the first heat transfer medium.
It is another object of the present invention to provide a cooling system that can operate with reduced fuel consumption of an aircraft.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a cooling system of the present invention adiabatically compresses a refrigerant gas serving as a first heat transfer medium with a compressor and converts the gas having a high temperature and a high pressure into a first gas. After conducting the heat to the heat exchanger and exchanging heat with the second heat transfer medium serving as a cooling source, the heat is guided to the expansion valve and adiabatically free-expanded to obtain a cold gas-liquid two-phase state and guided to the second heat exchanger. A cooling system comprising a first heat transfer medium circulating passage for cooling a fluid to be cooled by the latent heat of vaporization of the liquid phase portion, re-entering a gas as a gas, and circulating the first heat transfer medium. A fourth heat transfer medium circulation path that is a circulation path of a fourth heat transfer medium instead of the second heat transfer medium that serves as a cooling medium of the vessel; and the first heat exchanger is connected to the fourth heat transfer medium circulation path. Is provided with a plurality of separate heat exchangers, and separate cooling is performed in each of the plurality of heat exchangers. And adapted to heat exchange between the fluid and the fourth heat transfer medium as a source, and characterized by being configured the cooling system to solve the problem when using the cooling source alone.

FIG. 1 is a block diagram showing an embodiment of a cooling system provided by the present invention. The flow path relating to the cooling of the cooling system of the present invention shown in FIG. 1 includes a first heat transfer medium circulation path 10, a third heat transfer medium circulation path 17, a fourth heat transfer medium circulation path 18, and a second heat transfer medium flow path. Path 20, fifth heat transfer medium flow path 24
And five fluid flow paths. Heat is exchanged between the heat transfer media between the respective fluid flow paths via the heat exchanger. That is, the first heat transfer medium circulation path 10 and the fourth heat transfer medium circulation path 18 pass through the first heat exchanger 1, and the first heat transfer medium circulation path 10 and the third heat transfer medium circulation path 17 2 through the heat exchanger 2, the fourth heat transfer medium circulation path 18 and the second heat transfer medium flow path 20 through the third heat exchanger 21, and further the fourth heat transfer medium circulation path 18 and the fifth The heat transfer medium flow path 24 exchanges heat via the fourth heat exchanger.

The main structure of each heat transfer medium circulation path is as follows. That is, the first heat transfer medium circulating path 10 is a circulating path of a first heat transfer medium, which is a refrigerant gas, for example, an alternative chlorofluorocarbon gas, and the compressor 3 driven by the motor 3A, the control valve 16, the first heat exchanger (condenser) ) 1, expansion valve 5, second
A heat exchanger (evaporator) 2 is connected by a pipe constituting a circulation path. Further, a pipe line bypassing the compressor 3 is provided, and a control valve 4 is provided. In addition, a bypass line of the first heat exchanger that connects one port 16B of the control valve 16 and the outlet of the first heat exchanger 1 is provided. Further, a flow sensor 9 and a pressure sensor 15 are provided in a pipe at an outlet of the compressor 3, and a temperature sensor 7 and a pressure sensor 8 are provided in a pipe at an outlet of the evaporator 2.

The third heat transfer medium circulation path 17 is a circulation path for a heat transfer medium, for example, an ethylene glycol mixed liquid (third heat transfer medium), and the pump 11, the second heat exchanger 2, and the heat load 12 pass through the circulation path. They are connected by the constituent pipelines. Further, a temperature sensor 14 is provided in a pipe at the inlet of the heat load. The fourth heat transfer medium circulating path 18 is a circulating path of a fourth heat transfer medium, for example, an ethylene glycol mixed liquid, and the pump 19, the third heat exchanger 21, and the fourth heat exchanger 22 are connected by a pipe forming a circulating path. Have been. The second heat exchanger 21 has a second heat transfer medium facing the fourth heat transfer medium.
A heat transfer medium channel 20 is provided, and a control valve 23 and a temperature sensor 25 are provided at the outlet thereof. A fifth heat transfer medium flow path 24 is provided in the fourth heat exchanger 22 in a path facing the fourth heat transfer medium.
The control valve 26 is interposed at the outlet.

Next, the operation of the cooling system of FIG. 1 provided by the present invention will be described. The first heat transfer medium is a motor 3
A is adiabatically compressed by the compressor 3 driven by
It becomes a high-pressure gas and is led to the condenser 1. The opposed flow path of the first heat transfer medium circulation path 10 of the condenser 1 is a fourth heat transfer medium circulation path 18, and the high-temperature and high-pressure gas is cooled by the fourth heat transfer medium flowing through the fourth heat transfer medium circulation path 18. You. Most of the cooled gas is liquefied to become a gas-liquid two-phase fluid, which is guided to the expansion valve 5, and is adiabatically and freely expanded by the expansion valve 5.
It becomes a cold gas-liquid two-phase fluid and is input to the evaporator 2. The opposing flow path of the first heat transfer medium circulation path 10 of the evaporator 2 is a third heat transfer medium circulation path 25, and the cold gas-liquid two-phase fluid is circulated by the pump 11 to cool the heat load 12. The third heat transfer medium exchanges heat with the third heat transfer medium, and the third heat transfer medium is cooled and vaporized by the latent heat of vaporization and returns to the compressor inlet. The heat load 12 is cooled by the third heat transfer medium circulating in the third heat transfer medium circulation path 17.

The fourth heat transfer medium is connected to a fourth heat transfer medium circulation path 18.
Heat transfer medium circulation path 1 of third heat exchanger 21 interposed in
The heat exchange with the fluid (for example, fuel supplied to the engine) flowing through the second heat transfer medium flow path 20, which is the flow path opposite to the flow path 8, is cooled. Further, the fourth heat transfer medium includes a fifth heat transfer medium flow path 24 which is a flow path opposite to the fourth heat transfer medium circulation path 18 of the fourth heat exchanger 22 provided in the fourth heat transfer medium circulation path 18. Is also exchanged with a fluid flowing through the air (for example, ram air taken in from outside) to be cooled.

The output signal detected by the temperature sensor 14 is input to the controller 13, and when the temperature of the third heat transfer medium becomes lower (higher) than the target value, the rotation speed of the motor 3A is decreased (increased), and The temperature is controlled so that the flow rate of the first heat transfer medium in the evaporator 2 is decreased (increased) and the temperature of the third heat transfer medium is increased (decreased) by increasing (lowering) the inlet pressure of the third heat transfer medium.

Further, in order to operate the system stably, the signals of the temperature sensor 7 and the pressure sensor 8 are input to the controller 13 in the first heat transfer medium circulating path 10 so that the first heat transfer medium flowing into the compressor 3 is liquid. The complete gasification control for controlling the opening of the expansion valve 5 so as not to flow as it is is performed. In addition, the first
If the flow rate of the heat transfer medium decreases too much, surging occurs and becomes unstable. Therefore, the gas flow rate is detected by the flow rate sensor 9 and the pressure is detected by the pressure sensors 8 and 15, and the output signals thereof are also input to the controller 13, and the compressor 13 The compressor surging prevention control is performed in which the opening of a control valve 4 provided in a bypass pipe of the compressor 3 is controlled so that the flow rate of gas flowing into the compressor 3 does not become lower than a predetermined value. Further, the pressure sensor 15 detects the pressure of the first heat transfer medium at the inlet of the condenser 1 so that the first heat transfer medium compressed by the compressor 3 is not excessively cooled by the condenser 1 by the fourth heat transfer medium. The controller 13 also controls the condenser pressure to control the amount of the first heat transfer medium that bypasses the first heat exchanger 1 through one port 16A of the three-way valve 16 so that the pressure falls within a predetermined range. Have been done.

According to the cooling system of the present invention, the heat generated by the heat load 12 is cooled by the third heat transfer medium, and the third heat transfer medium whose temperature has risen is increased by the first heat transfer medium circulation path 10. The heat obtained by the first heat transfer medium is cooled by the evaporator 2 of the
At the fourth heat transfer medium circulating through the fourth heat transfer medium circulation path 18. Further, the fourth heat transfer medium flows through the second heat transfer medium passage 20 of the third heat exchanger 21 and is cooled by the second heat transfer medium which is a heat sink, for example, aircraft fuel. That is, the heat generated by the heat load 12 is transferred to the fuel as the heat sink and cooled by the fuel, and the transferred heat is accumulated in the form of a rise in the temperature of the fuel. However, if the fuel temperature rises too high,
There is a limit, for example, that the heat transfer medium becomes difficult to cool, the pressure of the first heat transfer medium increases, the load on the compressor increases, and the heat transfer medium becomes hard to cool. Therefore, the fifth heat transfer medium flow path 22 of the fourth heat exchanger 22 provided in the fourth heat transfer medium circulation path 18
The fifth heat transfer medium flowing through the air, for example, ram air taken in from outside the machine is also used for cooling, and the fourth heat transfer medium is cooled to release the heat to the outside air. However, while the aircraft is on the ground or flying at an extremely low speed, it is necessary to provide forced air blowing means such as a fan in the fifth heat transfer medium flow path 20 in order to take in outside air. In addition, when ram air is taken in during the cruise of the aircraft, drag occurs that is a resistance to the propulsion of the aircraft. Since the fuel consumption increases when a drag occurs, there is a need to reduce the cooling by taking in the outside air as much as possible. In the cooling system of the present invention, the system is configured so that both fuel and outside air can be used as a heat sink. While monitoring at 13, the fuel is used as a heat sink and the control valve 26 interposed at the ram air intake is closed. Then, when the fuel temperature approaches the limit, the control valve 26 is opened to take in the ram air and cool it. The operation control of such a system is also performed by the controller 13. In the illustrated example, the control valve 16 is provided in the first heat transfer medium circulation path in the pipe passing through the first heat exchanger 1 and in the bypass pipe. (1) It may be interposed in a pipe passing through the heat exchanger and its bypass pipe. Control valve 2
2 uses a three-way valve, but can be replaced with two control valves.

The cooling system according to the present invention is constructed as described above. By using a plurality of heat transfer media as a heat sink, for example, fuel and ram air together, each cooling medium can be used alone. The disadvantages can be compensated and the operation with the lowest fuel consumption is possible. Compared to systems that rely only on fuel for heat sinks, the operating range of the aircraft is expanded, and fuel consumption can be reduced compared to systems that rely solely on ram air, and operation with the least fuel consumption is possible by using multiple heat sinks together It is possible to provide a simple cooling system.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of a cooling system according to the present invention.

FIG. 2 is a diagram showing a configuration of a conventional cooling system.

[Explanation of symbols]

1. First heat exchanger (condenser) 2. Second heat exchanger (evaporator) 3. Compressor 3A. Motor 4.16,23,26..Control valve 5.Expansion valve 7,14. 25 ··· Temperature sensor 8, 15 ··· Pressure sensor 9 ··· Flow rate sensor 10 · · · First heat transfer medium circulation path 11 · · · Pump 12 · · · Heat load 13 · · · Controller 17 · · · Third heat transfer medium circulation path 18. Fourth heat transfer medium circulation path 19 Pump 20 Second heat transfer medium path 21 Third heat exchanger 22 Fourth heat exchanger 24 Fifth heat transfer medium flow path

Claims (1)

[Claims] 1. A refrigerant gas serving as a first heat transfer medium is adiabatically compressed by a compressor, and a high-temperature and high-pressure gas is led to a first heat exchanger to be interposed between the first heat exchanger and a second heat transfer medium serving as a cooling source. After the heat exchange, the liquid is guided to the expansion valve and adiabatically expanded freely, a cold gas-liquid two-phase state is obtained, the liquid is guided to the second heat exchanger, and the liquid to be cooled is cooled by the latent heat of vaporization of the liquid phase, and the gas is cooled. And a fourth heat transfer in place of the second heat transfer medium serving as a cooling medium for the first heat exchanger. A fourth heat transfer medium circulation path that is a medium circulation path; and a plurality of heat exchangers that are separate from the first heat exchanger provided in the fourth heat transfer medium circulation path. In which heat exchange can be performed between a fluid serving as a separate cooling source and the fourth heat transfer medium. Cooling system to be.