JP4453795B2 - Air conditioning system for aircraft - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an air conditioning system for an aircraft including a fixed wing aircraft and a rotary wing aircraft.
[0002]
[Prior art]
There are two types of methods for removing moisture contained in air in an air conditioning system of an aircraft: a low pressure dehumidification method and a high pressure dehumidification method. The conventional low-pressure dehumidification type air conditioning system shown in FIG. 2 cools the extracted air of the engine 102 compressed by the compressor 101 by heat exchange with the ram air in the heat exchanger 103, and expands the cooled extracted air in the expansion turbine 105. The water is then removed from the low-temperature air by the water separator 106 and supplied to the cabin of an aircraft cabin or the like. In the water separator 106, the water that has become mist due to the decompression of air by the expansion turbine 105 is condensed using a cloth-like member called coalescer and separated using centrifugal force. . Further, by allowing the engine bleed air to be introduced between the expansion turbine 105 and the water separator 106 via the valve 107, moisture icing in the water separator 106 is eliminated.
[0003]
The conventional high pressure dehumidification type air conditioning system shown in FIG. 3 cools the bleed air of the engine 202 compressed by the compressor 201 by heat exchange with the ram air in the heat exchanger 203, and the cooled bleed air is regenerated by the regenerative heat exchanger 205. Is further cooled by heat exchange with the low-temperature air in the condenser 206, thereby cooling the moisture in the extracted air below the dew point, and using the centrifugal force in the water separator 207 It is separated. The extracted air from which the moisture has been separated is used for cooling the extracted air before the moisture separation in the regenerative heat exchanger 205 and then expanded in the expansion turbine 208 to form low-temperature air. The low-temperature air is used for cooling the extraction air in the condenser 206 and then sent out into the aircraft cabin. Further, by allowing the engine bleed air to be introduced between the expansion turbine 208 and the condenser 206 via the valve 209, moisture icing in the bleed passage of the condenser 206 is eliminated.
[0004]
According to the high pressure dehumidification method, by performing dehumidification of the extraction air upstream of the expansion turbine 208, the expansion turbine outlet temperature can be lowered as compared with the low pressure dehumidification method, and the air supplied to the cabin or the like can be made low temperature. By reducing the air temperature at the outlet temperature of the expansion turbine 208, it is possible to reduce the amount of bleed air required to achieve the same cooling capacity, so that it is possible to reduce the amount of fuel required to operate the air conditioning system. Further, according to the high-pressure dehumidification method, the coalescer required in the low-pressure dehumidification method is not required, so that maintenance of the airframe is facilitated.
[0005]
However, in the high-pressure dehumidification type air conditioning system, moisture contained in the bleed air freezes in the condenser 206 to block the bleed air flow path, and there is a possibility that sufficient low-temperature air cannot be supplied to the cabin or the like. Therefore, a high-temperature engine bleed air is introduced downstream of the expansion turbine 208 through the valve 209 and mixed with low-temperature air, and a bypass flow path 206a that connects the inlet and outlet of the low-temperature air flow path in the condenser 206 is provided. This prevents the icing state from continuing in the capacitor 206.
[0006]
[Problems to be solved by the invention]
In the conventional high-pressure dehumidification type air conditioning system, even if the bypass channel 206a that connects the inlet and the outlet of the low-temperature air channel in the capacitor 206 is provided, the channel area of the low-temperature air in the bypass channel 206a is constant. For this reason, when the icing state in the capacitor 206 progresses, it has been unavoidable to introduce hot engine bleed air downstream of the expansion turbine. Therefore, the extraction flow rate cannot be sufficiently reduced, and the air temperature at the expansion turbine outlet cannot be sufficiently reduced.
[0007]
[Means for Solving the Problems]
The present invention provides engine bleed air compression means, compressed bleed air cooling means, water separation means from the cooled bleed air, and expansion of the water from which the water has been separated into low temperature air. Expansion means, and as cooling means, between extraction air flowing through an extraction flow path between the compression means and expansion means, and low-temperature air flowing through a low-temperature air flow path connected to the outlet of the expansion means In an air conditioning system for an aircraft having a heat exchanging section for performing heat exchange, a bypass flow path for bypassing the heat exchanging section with low temperature air flowing out from an outlet of the expansion means is connected to the low temperature air flow path, The low-temperature air flow rate in the bypass flow path is provided with a flow rate adjusting means for changing according to the pressure difference between the inlet and the outlet of the extraction flow path in the heat exchange section. The flow rate adjusting means can be constituted by a valve whose opening degree changes according to the pressure difference.
[0008]
According to this configuration, part of the low-temperature air from the expansion means to the heat exchange unit flows through the bypass flow path, so that the low-temperature air flow rate in the heat exchange unit is reduced, and the extraction air and the low-temperature air in the heat exchange unit are reduced. Heat exchange efficiency decreases. In addition, when the extraction flow path of the heat exchange section is frozen by water contained in the extraction, the pressure difference between the inlet and the outlet of the extraction flow path in the condenser increases as the extraction flow path becomes narrower, The opening degree of the bypass valve is increased, the low-temperature air flow rate in the heat exchange part is decreased, and the low-temperature air flow rate in the bypass flow path is increased. As a result, the heat exchange efficiency can be changed by adjusting the low-temperature air flow rate in the heat exchange unit according to the degree of freezing, and the low-temperature air temperature can be lowered as much as possible while eliminating the freezing. . That is, the freezing can be eliminated without mixing the hot bleed air with the low temperature air as in the prior art, and the low temperature air finally supplied to the cabin or the like can be lowered to a temperature that cannot be achieved by the prior art. In addition, since high-temperature extraction is not used to eliminate the icing, the required amount of extraction flow can be reduced, and the amount of fuel consumed to operate the air conditioning system can be reduced.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
A high-pressure dehumidification aircraft air-conditioning system 1 shown in FIG. 1 obtains low-temperature air by an air refrigeration cycle. The air extracted from the engine 2 is heated by the first heat exchanger 3 with the ram air introduced from outside the airframe. After cooling by exchange, it is compressed by the centrifugal compressor 4, cooled again by heat exchange with the ram air in the second heat exchanger 5, and further cooled by heat exchange in the regenerative heat exchanger 6, and then the condenser (heat exchange Part) 7 is cooled. Water in the extracted air is condensed by cooling in the regenerative heat exchanger 6 and the condenser 7. The condensed water is separated and removed by centrifugal force in the water separator 8. The extracted air from which the moisture has been separated is used for cooling the extracted air before the moisture separation in the regenerative heat exchanger 6, and then introduced into the expansion turbine 9, where it is expanded in the expansion turbine 9 to produce low-temperature air. After this low temperature air is used for cooling the bleed air in the condenser 7, it is supplied as conditioned air into the cabin of an aircraft cabin or the like. The compressor 4 is started by a motor 4a at the time of starting, and is driven by power taken out from the expansion turbine 9 after starting.
[0010]
In the condenser 7, heat exchange is performed between the bleed air flowing through the bleed air passage between the compressor 4 and the expansion turbine 9 and the low-temperature air flowing through the low-temperature air passage 15 connected to the outlet of the expansion turbine 9. To cool the engine bleed air.
[0011]
The low-temperature air flow path 15 is connected to a bypass flow path 10 for low-temperature air flowing out from the outlet of the expansion turbine 9 to bypass the condenser 7. In the present embodiment, the bypass flow path 10 is connected to the upstream and downstream portions of the capacitor 7 in the low-temperature air flow path 15. As a result, part of the low-temperature air flowing out from the outlet of the expansion turbine 9 bypasses the condenser 7 and reaches the supply port to the low-temperature air supply space such as the cabin. A bypass valve 11 is provided in the bypass flow path 10 as flow rate adjusting means for changing the low-temperature air flow rate in the bypass flow path 10 according to the pressure difference between the inlet and outlet of the extraction flow path in the condenser 7. The opening of the bypass valve 11 increases when the pressure difference between the inlet 7a and the outlet 7b of the extraction flow path in the condenser 7 increases, and the opening decreases when the pressure difference decreases. For example, a differential pressure detection sensor that detects a pressure difference between the inlet 7a and the outlet 7b is connected to a control device mounted on an aircraft, and an electromagnetic valve controlled by the control device is bypassed according to the detected differential pressure. The bypass valve 11 can be a valve 11 or a pressure control valve having a spool that is displaced by the direct action of the pressure difference between the inlet 7a and the outlet 7b.
[0012]
According to the above configuration, part of the low-temperature air from the expansion turbine 9 toward the condenser 7 flows through the bypass flow path 10, so that the low-temperature air flow rate in the condenser 7 decreases, and the heat exchange efficiency between the extracted air and the low-temperature air in the condenser 7 is increased. descend. In addition, when moisture contained in the bleed air in the condenser 7 freezes and blocks the bleed air passage, the pressure difference between the inlet 7a and the outlet 7b of the bleed air passage in the condenser 7 increases as the bleed air passage becomes narrower. The opening degree of the bypass valve 11 increases, the low-temperature air flow rate in the condenser 7 decreases, and the low-temperature air flow rate in the bypass flow path 10 increases. Thereby, the heat exchange efficiency can be changed by adjusting the low-temperature air flow rate in the condenser 7 according to the degree of freezing, and the low-temperature air temperature can be lowered as much as possible while eliminating freezing. That is, the freezing can be eliminated without mixing the hot bleed air with the low temperature air as in the prior art, and the low temperature air finally supplied to the cabin or the like can be lowered. In addition, since high-temperature extraction is not used to eliminate the icing, the required amount of extraction flow can be reduced, and the amount of fuel consumed to operate the air conditioning system can be reduced. Thereby, the low-temperature air finally supplied to the cabin or the like can be lowered to a temperature that cannot be achieved by the prior art. For example, conventionally, the lower limit temperature of conditioned air, which is about -10 deg FDAR (dry bulb temperature), can be reduced to -20 deg FDAR or less.
[0013]
【The invention's effect】
According to the present invention, it is possible to provide an aircraft air conditioning system that can reduce the required amount of engine bleed, lower the obtained low-temperature air temperature, save energy, reduce the size and weight of the system, and reduce the cost.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a configuration of an aircraft air conditioning system according to an embodiment of the present invention. FIG. 2 is an explanatory diagram of a configuration of a conventional aircraft air conditioning system. FIG. 3 is an explanatory diagram of a configuration of a conventional aircraft air conditioning system. ]
1 Air-conditioning system for aircraft 4 Compressor 7 Condenser (Heat exchange part)
8 Water separator 9 Expansion turbine 10 Bypass passage 11 Bypass valve 15 Low temperature air passage

Claims (1)

Compression means for engine bleed,
Means for cooling the compressed bleed air;
Means for separating moisture from the cooled bleed air;
An expansion means for expanding the extracted air from which the moisture has been separated into low temperature air;
As the cooling means, heat for exchanging heat between the bleed air flowing through the bleed air flow path between the compression means and the expansion means and the low temperature air flowing through the low temperature air flow path connected to the outlet of the expansion means. In an air conditioning system for aircraft having an exchange part,
The low-temperature air flow path is connected to a bypass flow path for the low-temperature air flowing out from the outlet of the expansion means to bypass the heat exchange unit,
An air conditioning system for an aircraft, comprising a flow rate adjusting means for changing a low-temperature air flow rate in the bypass flow path according to a pressure difference between an inlet and an outlet of the extraction flow path in the heat exchange section.

Images