CA2313788A1 - Air-conditioning system for airplane cabins - Google Patents
Air-conditioning system for airplane cabins Download PDFInfo
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- CA2313788A1 CA2313788A1 CA002313788A CA2313788A CA2313788A1 CA 2313788 A1 CA2313788 A1 CA 2313788A1 CA 002313788 A CA002313788 A CA 002313788A CA 2313788 A CA2313788 A CA 2313788A CA 2313788 A1 CA2313788 A1 CA 2313788A1
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- conditioning system
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- 238000004378 air conditioning Methods 0.000 title claims abstract description 56
- 230000001143 conditioned effect Effects 0.000 claims abstract description 16
- 238000000034 method Methods 0.000 claims description 21
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 19
- 230000006835 compression Effects 0.000 claims description 16
- 238000007906 compression Methods 0.000 claims description 16
- 238000009833 condensation Methods 0.000 claims description 6
- 230000005494 condensation Effects 0.000 claims description 6
- 238000007791 dehumidification Methods 0.000 claims description 6
- 230000008569 process Effects 0.000 claims description 6
- 230000003750 conditioning effect Effects 0.000 claims description 3
- 238000010276 construction Methods 0.000 claims 1
- 238000003809 water extraction Methods 0.000 abstract description 20
- 239000003570 air Substances 0.000 description 78
- 238000001816 cooling Methods 0.000 description 11
- 230000002349 favourable effect Effects 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 101000807985 Homo sapiens Testis-specific basic protein Y 2 Proteins 0.000 description 3
- 102100039002 Testis-specific basic protein Y 2 Human genes 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 239000012080 ambient air Substances 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 230000001172 regenerating effect Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
- B64D13/00—Arrangements or adaptations of air-treatment apparatus for aircraft crew or passengers, or freight space, or structural parts of the aircraft
- B64D13/06—Arrangements or adaptations of air-treatment apparatus for aircraft crew or passengers, or freight space, or structural parts of the aircraft the air being conditioned
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T50/00—Aeronautics or air transport
- Y02T50/40—Weight reduction
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T50/00—Aeronautics or air transport
- Y02T50/50—On board measures aiming to increase energy efficiency
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- Health & Medical Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Pulmonology (AREA)
- Engineering & Computer Science (AREA)
- Aviation & Aerospace Engineering (AREA)
- Air-Conditioning For Vehicles (AREA)
- Drying Of Gases (AREA)
- Engine Equipment That Uses Special Cycles (AREA)
Abstract
An air-conditioning system in particular for aircraft is proposed wherein pressurized, moisture-containing air is conditioned for air-conditioning the cabin. The pressurized air is compressed further in two separate stages, dehumidified in a high-pressure water extraction cycle and subsequently expanded in one or two turbine stages. Depending on the design one can thereby achieve ice-free conditioned air or a high efficiency of the air-conditioning-system, in particular if two turbine stages are provided and the energy gained in the particular turbine stages is utilized regeneratively, distributed over the compressor stages.
Description
Air-conditioning system for airplane cabins This invention relates to an air-conditioning system for conditioning moisture-containing, pressurized air for air-conditioning a room, in particular for air-condi-tinning airplane cabins, and to a corresponding method.
Fresh air for air-conditioning airplane cabins is conditioned from the air (known as bleed) bled off the engine at high pressure and high temperature.
Air-conditioning systems draw the necessary cooling power out of the pressure and tem-perature potential of the engine air. In the course of the fresh-air conditioning proc-ess the bleed is cooled, dehumidified and expanded to the cabin pressure of 1 bar in ground operation or about 0.8 bars in flight operation. Special value is attached in fresh-air conditioning to dehumidification in order to prevent icing of individual components of the air-conditioning system and ice crystallization in the fresh air to be conditioned. The necessity of dehumidification exists mainly in ground operation, however, because in flight operation, i.e. at high altitudes, ambient air and thus the bled-off engine air is already extremely dry.
With reference to Fig. 4 an air-conditioning system will be described in the following as is used in present-day Airbus and Boeing passenger airplanes, for ex-ample the A330/340 and Boe 757/767.
Via flow control valve FCYthe amount of bleed required for supplying fresh air to the cabin is bled off an engine at about 2 bars and 200°C. In ground operation bleed is withdrawn from an auxiliary engine at about 3 bars. The bleed is first passed through primary heat exchanger PHX and cooled to about 100°C. Then the bleed is compressed further in compressor C to about 4.5 bars and 160°C and cooled again to about 45°C in main heat exchangerMHX. The high pressure of 4.5 bars is necessary to be able to realize a high degree of dehumidification in the following water extrac-tion cycle. This air cycle system is therefore also known as a "high-pressure water extraction cycle".
The high-pressure water extraction cycle comprises condenser CON, as pro-posed in EP 0 019 492 A3, and water extractor WE following condenser CON.
Compressed, cooled bleed is cooled in condenser CON by about dT = -15K, con-densed water is then extracted in water extractor WE, and the thus dehumidified air is subsequently expanded in turbine T to the cabin pressure of about 1 bar, the tem-perature at the turbine outlet being about -30°C. Thus conditioned bleed, before be-ing mixed as fresh air with recirculated cabin air in a mixing chamber, is passed through condenser CON of the high-pressure water extraction cycle in heat-exchang-ing fashion in order to cool the compressed, cooled bleed to the temperature neces-sary for water extraction in water extractor WE. Air expanded in turbine T and cooled is thereby accordingly heated again by dT = +15K to about -15°C.
The conditioned air is then mixed with recirculated cabin air in a mixing chamber (not shown). Temperature control valve TCYcan be used to increase the temperature at the turbine outlet to obtain an optimum mixing temperature with the admixed, recirculated cabin air. For this purpose part of the bleed precooled in pri-mary heat exchanger PHX is branched off and resupplied to the conditioned air stream after turbine T.
The high-pressure water extraction cycle has, in addition to condenser CON, heat exchanger REH (reheater) preceding condenser CON. Compressed, cooled bleed is first passed through heat exchanger REH before entering condenser CON, and subsequently the dehumidified air is passed through heat exchanger REH
before entering turbine T. Heat exchanger REH has substantially the function of heating the dehumidified air by about dT = SK and vaporizing residual moisture while simulta-neously recovering energy before air enters the turbine. Residual moisture in the form of fine droplets can destroy the turbine surfaces since air almost reaches the speed of sound in turbine T. A second function of heat exchanger REH is to relieve condenser CON by cooling compressed, cooled bleed before it enters condenser CON by dT = -SK.
It is typical of such an air-conditioning system that the energy gained in turbine T is used to drive compressor C, on the one hand, and fan F, on the other. All three wheels, that is turbine/compressor/fan, are disposed on a common shaft and form air cycle machine ACM, also known as a three-wheel machine Fan F conveys a cooling air stream branched off from ambient air through a cooling shaft in which primary and main heat exchangers PHX, MHX are disposed. Fan F must be driven actively by turbine T in particular in ground operation. In flight operation ram air suffices, it being optionally throttled by a valve at the cooling shaft inlet.
The overall system is designed for ground operation at an ambient temperature of 38°C. In order to optimize the effectiveness of the heat-exchange process in the cooling shaft, water gained in the high-pressure water extraction cycle is supplied at a temperature of about T = 20°C and a pressure of 3.5 bars in the cooling shaft inlet in fine droplets to be vaporized therein, thereby improving the effectiveness of the heat exchangers.
In case air cycle machine ACM fails completely, for example because the nec-essary mass flow rate of compressed air is not attainable for fulfilling the parameters necessary for the system to work, bypass valve BPV is provided for bypassing tur-bine T. In this case check valve CV opens automatically since an overpressure trig-gering check valve CV builds up before compressor C as turbine T is not driven. The opening of check valve CV causes compressor C to be bypassed or "short-circuited".
In this state, fresh air is supplied directly through primary and main heat exchangers PHX, MHX to the mixing chamber following the air-conditioning system to be mixed with recirculated cabin air.
As mentioned at the outset, icing in the conditioned fresh air is a problem.
In order to avoid icing, anti-icing valve AIV is provided for directly branching off part of the air bled off the engine and resupplying it to the conditioned air stream after turbine T. A further way of avoiding ice is to design the turbine such that no tem-peratures below 0°C occur at the turbine outlet. However, this latter variant requires much more energy if the same cooling power is to be reached. Therefore, it is pref erable to supply hot air at the turbine outlet.
An improved variant of this air-conditioning system provides that air cycle ma-chine ACM is extended by a second turbine. This makes the three-wheel machine, turbine/compressor/fan, into a four-wheel machine, turbine/turbine/compressor/fan (US 5,086,622). The second turbine is disposed on a common shaft with the other wheels in order to recycle the energy gained by the turbines into the air-conditioning system, as in the conventional three-wheel system. The second turbine supplements the first turbine such that air dehumidified in the high-pressure water extraction cy-cle is expanded in two stages, the condenser of the high-pressure water extraction cycle being disposed with the air pipe between the two turbines in heat-exchanging fashion. This is more favorable energetically than the conventional structure of the air-conditioning system because air exiting the first turbine is comparatively warm, preferably above 0°C to avoid ice, and this air is heated in condenser CON by for example dT = +15 Kelvin to a comparatively high energy level, so that the second turbine can utilize this high energy level to gain energy which gets lost in the con-ventional system. This system is known in expert circles as a "condensing cycle".
A development of the four-wheel machine is described in WO 99/24318 and generally designated a 2+2-wheel system. The two turbines are accordingly disposed on separate shafts, the first turbine with the compressor and the second turbine with the fan being on a common shaft in each case.
The problem of the present invention is to adapt the above-described air-condi-tioning system or method so that it can be designed more flexibly and the overall aff ciency optimized more easily, in particular to make it adaptable to the particular system requirements more flexibly and therefore better energetically through a greater number of freely selectable system parameters.
A further problem is to provide an air-conditioning system and method with which one can reduce icing during air conditioning.
A further problem is to improve overall eff ciency over known systems and methods.
Yet a further problem is to be seen in increasing overall efficiency in particular in flight operation.
These problems are solved by the air-conditioning system and method having the features stated in the independent patent claims and claims dependent thereon.
It is essential to the invention that compression of bleed is effected in two stages. One of the two compression stages procures the energy required for compres-sion in conventional fashion by regenerative utilization of energy gained during ex-pansion of dehumidified air. For this purpose one of the two compressor wheels is disposed on a common shaft with a turbine wheel, for example, so that compressor wheel and turbine wheel, optionally with a fan wheel in addition, form a (first) two-or three-wheel air cycle machine. The compressor wheel of the first compression stage is preferably disposed on a common shaft with the turbine wheel, but it can also be the compressor wheel of the second compressor stage. The other compressor wheel can be driven with energy external to the system for example. This makes it possible to design the (first) air cycle machine such that the compressor and turbine disposed on a common shaft have comparatively high efficiency. This initially re-sults in the compressor power of the air cycle machine being below the compressor power necessary for bringing the engine air to be conditioned to the pressure neces-sary for air dehumidification. The lacking compressor power is therefore provided by the additional compressor stage. This permits the air-conditioning system to be designed flexibly and the overall e~ciency optimized easily.
Due to the second compressor stage it is in particular possible to produce ice-free conditioned air. The invention exploits the fact that at a given temperature the amount of water condensing out of air increases with rising pressure. Since the tem-perature can only be influenced within limits due to the system, in particular because compressed engine air cooled in the main heat exchanger cannot be cooled below ambient temperature in the cooling shaft (designed for 38°C ambient temperature), a comparatively high compression pressure of >_ 4.6 bars can be produced with the additional compressor stage to reach the desired high degree of condensation in the high-pressure water extraction cycle. Freedom from ice is reached e.g. at -10°C and 1 bar with < 1.8 g of water per kilogram of dry air.
Instead of having a power source external to the system for the additional com-pressor, one can also operate the latter regeneratively by effecting not only compres-sion of bleed but also expansion of dehumidified air in two stages, for example in two separate turbines, and utilizing the energy delivered by the turbines for the first compressor stage, on the one hand, and for the second compressor stage, on the other. The air-conditioning system then comprises two machines each having at least a compressor wheel and a turbine wheel on a common shaft. Additionally the fan can be disposed on one shaft and a motor on the other shaft, whereby the motor can also be designed as a generator.
Disposing the compressor and turbine wheels on two separate shafts or in two separate machines permits much more flexible design of the overall system than conventional air-conditioning systems. One attains an optimum design in particular of compressor and turbine.
Freedom from ice can be obtained without any problem in particular when not only compression of bleed but also condensation of moisture contained in the air is effected in two stages in the high-pressure water extraction cycle. For this purpose a first condenser of the high-pressure water extraction cycle is disposed for heat ex-change with dehumidified air before the turbine inlet, in case of two-stage expansion before the second turbine inlet, and a second condenser of the high-pressure water extraction cycle for heat exchange with dehumidified and expanded air after the tur-bine outlet, compressed air being passed through said condensers in heat-exchanging fashion in order to condense water and then extract it. Effectiveness of dehumidifi-cation is increased substantially by two-stage condensation. This holds in particular when expansion is also effected in two turbine stages.
When small amounts of ice in the cooling air are no great problem and high ef ficiency of the overall system is important, it is advantageous to combine two-stage compression with two-stage expansion, compressed air being passed in heat-exchanging fashion through a condenser disposed between first and second turbines to extract moisture. Efficiency can be fiu~ther improved if dehumidified air is guided past compressed, not yet dehumidified air in heat-exchanging fashion in a reheater before entering the first turbine stage. This relieves the condenser, on the one hand, since compressed air is precooled before entering the condenser. On the other hand, any residual moisture contained in the dehumidified air is vaporized before the first turbine inlet so that the turbine surfaces are protected from being destroyed by water drops. In terms of efficiency this variant is to be ranked the most favorable.
The invention offers the further advantage that it is possible to switch off the additional compressor stage and optionally the turbine stage driving said compressor stage by means of suitable bypass circuits. This is useful in particular in flight op-eration, when air moisture and freedom from ice of the cooling air play no part so that high compression for the high-pressure water extraction cycle is unnecessary. In flight operation one can completely switch off one of the two machines by opening -and/or closing valves, thereby avoiding unnecessary losses and therefore increasing efficiency in flight operation.
Designing the air-conditioning system with two separate machines each com-prising compressor and turbine wheel on a common shaft, one of which can be switched off in flight operation, offers further advantages resulting from the fact that a greater pressure ratio is available in ground operation than in flight operation due to the system. This makes it energetically favorable to provide a relatively small tur-bine nozzle (baffle screen cross section) in ground operation. Said small nozzle is realized by connecting the two turbine stages in series, resulting in a "total nozzle"
smaller than each individual nozzle. In flight operation about the same volume flow is required for air-conditioning the airplane cabin despite a lower available pressure ratio, however, so that in flight operation a large nozzle would be necessary for about the same air flow. Since one machine and thus one turbine stage is turned off for the overall system in flight operation, a large nozzle results by reason of the sole remaining turbine of the second turbine stage for the overall system. One can thus increase efficiency in flight operation. This gain in efficiency is preferably utilized for designing the primary and main heat exchangers with minimal overall size and weight, under the constraint that the necessary volume flow rate is just met.
In the final effect one can thus achieve a smaller overall size and thus lower total weight of the air-conditioning system by the measure of providing two machines instead of only one machine.
A further advantage resulting when the air-conditioning system has two sepa-rate machines each with a coupled compressor and turbine is that if one machine fails at least the other machine still works and the air-conditioning system can be operated further without restriction. With the redundancy required for aircraft, this means that one fewer air conditioner or "pack" per aircraft is necessary, for example only two packs instead of three. As a consequence, the accordingly lower number of components decreases weight, increases the reliability of the installation and reduces expense for maintenance and repair.
Finally, it is to be ascertained that both in ground operation with two machines and in flight operation with one switched-off machine the energy gained during ex--g-pansion in the turbine or turbines is largely recovered via the two compressor stages (ground operation) or the sole remaining compressor stage (flight operation).
In the following the invention will be described by way of example with refer-ence to Figures 1 to 3, in which:
Figure 1 shows a diagram of an inventive air-conditioning system, Figure 2 shows a diagram of an improved embodiment of the system of Fig-ure 1, in particular for producing ice-free conditioned air, Figure 3 shows a diagram of an improved embodiment of the system of Fig-ure 1 with improved efficiency, and Figure 4 shows an air-conditioning system according to the prior art.
Figure 1 shows an air-conditioning system differing from the air-conditioning system described in Figure 4 with respect to the prior art substantially in that two compressors C1 and C2 are provided in order to bring bleed cooled in primary heat exchanger PHX to the pressure necessary for high-pressure water extraction.
Com-pressors C1 and C2 are to be designed depending on whether freedom from ice or high efficiency of the air-conditioning system is more important. In Figure 1, com-pressor C1 of the first compressor stage together with turbine T and fan F
form three-wheel machine ACM. That is, compressor C 1 and fan F are driven regenera-tively by energy gained in turbine T. Compressor C2 of the second compression stage is operated by separate motor M, i.e. by external energy. Check valve CYZ
opens automatically when compressor C2 is blocked or when motor M of compres-sor C2 is not switched off in flight operation for example. Check valve CVl opens automatically when air cycle machine ACM is blocked or bypass valve BPY2 is ac-tively opened.
The air-conditioning system schematically shown in Figure 1 otherwise corre-sponds fundamentally in structure and function to the system of Figure 4, whereby it should be taken into account that the reheater is not absolutely necessary but of great advantage in particular in case absolute freedom from ice is to be achieved.
Figure 2 shows a further development of the invention. In the air-conditioning system shown schematically therein, dehumidified air is expanded in two stages via turbines Tl and T2. Energy gained during expansion in turbine Tl is utilized regen-eratively to drive compressor C2, while energy delivered by turbine T2 is utilized regeneratively by compressor Cl, as before. In addition to condenser CONl in the high pressure dewatering cycle, through which condensed bleed is guided in heat-exchanging fashion past dehumidified air expanded in turbine Tl, second condenser CON2 is provided through which air precooled in condenser CONI is guided in heat-exchanging fashion past air expanded by turbine T2. Condensers CONI and CON2 are especially advantageous when conditioned air is to be free from ice.
Oth-erwise one can do without condenser CON2, which one does in particular when high efficiency of the overall system is to be achieved.
Before air expanded in the first turbine stage enters condenser CONl, water extractor WE2 is advantageously provided in addition to water extractor WEl pro-vided in the high-pressure water extraction cycle. Extracted water is supplied to ram-air heat exchangers MHXlPHX to be vaporized therein. Water extractor WE2 is ad-vantageous in particular when air cycle machine ACM is blocked, since the effec-tiveness of first water extractor WEl is greatly restricted here.
Further, one can open economy valve ECV to switch off the high-pressure wa-ter extraction cycle, which is useful in particular when air cycle machine ACM
fails and not enough pressure is available for energetically suitable utilization of the high-pressure water extraction cycle. Water extraction is then effected at low pressure by water extractor WE2. Condensers CONI and CONZ are inoperative in this case.
As in the air-conditioning system described above, one can switch off the ma-chine comprising turbine Tl and compressor C2 in particular for flight operation by opening bypass valve BPYI. By opening bypass valve BPY2 one can also bypass air cycle machine ACM, in particular if it fails.
Figure 2 shows optional motor M, with which the efficiency of the system can be optimized, by dotted lines on the shaft interconnecting turbine Tl and compressor C2. One can either make additional energy available to the system. Or, and in par-ticular, one can utilize the motor as a generator in order to supply surplus energy to the board wiring.
While the air-conditioning system shown in Figure 2 is in particular suitable for providing ice-free conditioned air, Figure 3 schematically shows an air-condi-tinning system having especially favorable e~ciency. As described with respect to Figure 4 (prior art), reheater REH is disposed before turbine Tl and condenser CON
after turbine Tl in heat-exchanging fashion for compressed air to flow through and for condensation of moisture contained therein. Reheater REH can fundamentally be omitted, but is advantageous for the reasons stated above. Moisture contained in compressed air is condensed in condenser CON at a comparatively high energy level, in contrast to the prior art described in Figure 4, whereby this energy can be utilized in turbine T2 as fundamentally proposed in US 5,086,622. However, in US
5,086,622 turbines Tl and T2 are disposed jointly with compressor C1 and fan F
on a common shaft in a single air cycle machine ACM. Since according to the invention compression is divided into two stages, and turbine Tl plus compressor C2 and tur-bine T2 plus compressor C1 each form separate machines, efficiency can be in-creased further because the design of the air-conditioning system is altogether more variable.
As described in Figure 2, economy valves ECVl and ECVZ serve optionally to bypass the high-pressure water extraction cycle. By opening bypass valve BPVl one bypasses the machine comprising turbine Tl and compressor C2 in flight operation.
Bypass valve BPY2 accordingly serves to bypass air cycle machine ACM if it fails.
Both bypass valves can also be used optionally as temperature control valves.
Tem-perature control valve TCV2 is likewise optional, while temperature control valve TCV4 should preferably be provided in the air-conditioning system. As mentioned above, one can actually omit reheater REH, but it is advantageous for the reasons stated at the outset.
Depending on the system requirement and/or to simplify the system, individual valves can be omitted, as mentioned above, or they can be partly combined. In par-ticular one can for example combine valves ECYI, BPVl and ECYZ into one line with only one valve, resulting in a less complex system altogether. The installation is then optimized for flight operation with a switched-off machine (turbine Tl/com-pressor C2).
Fresh air for air-conditioning airplane cabins is conditioned from the air (known as bleed) bled off the engine at high pressure and high temperature.
Air-conditioning systems draw the necessary cooling power out of the pressure and tem-perature potential of the engine air. In the course of the fresh-air conditioning proc-ess the bleed is cooled, dehumidified and expanded to the cabin pressure of 1 bar in ground operation or about 0.8 bars in flight operation. Special value is attached in fresh-air conditioning to dehumidification in order to prevent icing of individual components of the air-conditioning system and ice crystallization in the fresh air to be conditioned. The necessity of dehumidification exists mainly in ground operation, however, because in flight operation, i.e. at high altitudes, ambient air and thus the bled-off engine air is already extremely dry.
With reference to Fig. 4 an air-conditioning system will be described in the following as is used in present-day Airbus and Boeing passenger airplanes, for ex-ample the A330/340 and Boe 757/767.
Via flow control valve FCYthe amount of bleed required for supplying fresh air to the cabin is bled off an engine at about 2 bars and 200°C. In ground operation bleed is withdrawn from an auxiliary engine at about 3 bars. The bleed is first passed through primary heat exchanger PHX and cooled to about 100°C. Then the bleed is compressed further in compressor C to about 4.5 bars and 160°C and cooled again to about 45°C in main heat exchangerMHX. The high pressure of 4.5 bars is necessary to be able to realize a high degree of dehumidification in the following water extrac-tion cycle. This air cycle system is therefore also known as a "high-pressure water extraction cycle".
The high-pressure water extraction cycle comprises condenser CON, as pro-posed in EP 0 019 492 A3, and water extractor WE following condenser CON.
Compressed, cooled bleed is cooled in condenser CON by about dT = -15K, con-densed water is then extracted in water extractor WE, and the thus dehumidified air is subsequently expanded in turbine T to the cabin pressure of about 1 bar, the tem-perature at the turbine outlet being about -30°C. Thus conditioned bleed, before be-ing mixed as fresh air with recirculated cabin air in a mixing chamber, is passed through condenser CON of the high-pressure water extraction cycle in heat-exchang-ing fashion in order to cool the compressed, cooled bleed to the temperature neces-sary for water extraction in water extractor WE. Air expanded in turbine T and cooled is thereby accordingly heated again by dT = +15K to about -15°C.
The conditioned air is then mixed with recirculated cabin air in a mixing chamber (not shown). Temperature control valve TCYcan be used to increase the temperature at the turbine outlet to obtain an optimum mixing temperature with the admixed, recirculated cabin air. For this purpose part of the bleed precooled in pri-mary heat exchanger PHX is branched off and resupplied to the conditioned air stream after turbine T.
The high-pressure water extraction cycle has, in addition to condenser CON, heat exchanger REH (reheater) preceding condenser CON. Compressed, cooled bleed is first passed through heat exchanger REH before entering condenser CON, and subsequently the dehumidified air is passed through heat exchanger REH
before entering turbine T. Heat exchanger REH has substantially the function of heating the dehumidified air by about dT = SK and vaporizing residual moisture while simulta-neously recovering energy before air enters the turbine. Residual moisture in the form of fine droplets can destroy the turbine surfaces since air almost reaches the speed of sound in turbine T. A second function of heat exchanger REH is to relieve condenser CON by cooling compressed, cooled bleed before it enters condenser CON by dT = -SK.
It is typical of such an air-conditioning system that the energy gained in turbine T is used to drive compressor C, on the one hand, and fan F, on the other. All three wheels, that is turbine/compressor/fan, are disposed on a common shaft and form air cycle machine ACM, also known as a three-wheel machine Fan F conveys a cooling air stream branched off from ambient air through a cooling shaft in which primary and main heat exchangers PHX, MHX are disposed. Fan F must be driven actively by turbine T in particular in ground operation. In flight operation ram air suffices, it being optionally throttled by a valve at the cooling shaft inlet.
The overall system is designed for ground operation at an ambient temperature of 38°C. In order to optimize the effectiveness of the heat-exchange process in the cooling shaft, water gained in the high-pressure water extraction cycle is supplied at a temperature of about T = 20°C and a pressure of 3.5 bars in the cooling shaft inlet in fine droplets to be vaporized therein, thereby improving the effectiveness of the heat exchangers.
In case air cycle machine ACM fails completely, for example because the nec-essary mass flow rate of compressed air is not attainable for fulfilling the parameters necessary for the system to work, bypass valve BPV is provided for bypassing tur-bine T. In this case check valve CV opens automatically since an overpressure trig-gering check valve CV builds up before compressor C as turbine T is not driven. The opening of check valve CV causes compressor C to be bypassed or "short-circuited".
In this state, fresh air is supplied directly through primary and main heat exchangers PHX, MHX to the mixing chamber following the air-conditioning system to be mixed with recirculated cabin air.
As mentioned at the outset, icing in the conditioned fresh air is a problem.
In order to avoid icing, anti-icing valve AIV is provided for directly branching off part of the air bled off the engine and resupplying it to the conditioned air stream after turbine T. A further way of avoiding ice is to design the turbine such that no tem-peratures below 0°C occur at the turbine outlet. However, this latter variant requires much more energy if the same cooling power is to be reached. Therefore, it is pref erable to supply hot air at the turbine outlet.
An improved variant of this air-conditioning system provides that air cycle ma-chine ACM is extended by a second turbine. This makes the three-wheel machine, turbine/compressor/fan, into a four-wheel machine, turbine/turbine/compressor/fan (US 5,086,622). The second turbine is disposed on a common shaft with the other wheels in order to recycle the energy gained by the turbines into the air-conditioning system, as in the conventional three-wheel system. The second turbine supplements the first turbine such that air dehumidified in the high-pressure water extraction cy-cle is expanded in two stages, the condenser of the high-pressure water extraction cycle being disposed with the air pipe between the two turbines in heat-exchanging fashion. This is more favorable energetically than the conventional structure of the air-conditioning system because air exiting the first turbine is comparatively warm, preferably above 0°C to avoid ice, and this air is heated in condenser CON by for example dT = +15 Kelvin to a comparatively high energy level, so that the second turbine can utilize this high energy level to gain energy which gets lost in the con-ventional system. This system is known in expert circles as a "condensing cycle".
A development of the four-wheel machine is described in WO 99/24318 and generally designated a 2+2-wheel system. The two turbines are accordingly disposed on separate shafts, the first turbine with the compressor and the second turbine with the fan being on a common shaft in each case.
The problem of the present invention is to adapt the above-described air-condi-tioning system or method so that it can be designed more flexibly and the overall aff ciency optimized more easily, in particular to make it adaptable to the particular system requirements more flexibly and therefore better energetically through a greater number of freely selectable system parameters.
A further problem is to provide an air-conditioning system and method with which one can reduce icing during air conditioning.
A further problem is to improve overall eff ciency over known systems and methods.
Yet a further problem is to be seen in increasing overall efficiency in particular in flight operation.
These problems are solved by the air-conditioning system and method having the features stated in the independent patent claims and claims dependent thereon.
It is essential to the invention that compression of bleed is effected in two stages. One of the two compression stages procures the energy required for compres-sion in conventional fashion by regenerative utilization of energy gained during ex-pansion of dehumidified air. For this purpose one of the two compressor wheels is disposed on a common shaft with a turbine wheel, for example, so that compressor wheel and turbine wheel, optionally with a fan wheel in addition, form a (first) two-or three-wheel air cycle machine. The compressor wheel of the first compression stage is preferably disposed on a common shaft with the turbine wheel, but it can also be the compressor wheel of the second compressor stage. The other compressor wheel can be driven with energy external to the system for example. This makes it possible to design the (first) air cycle machine such that the compressor and turbine disposed on a common shaft have comparatively high efficiency. This initially re-sults in the compressor power of the air cycle machine being below the compressor power necessary for bringing the engine air to be conditioned to the pressure neces-sary for air dehumidification. The lacking compressor power is therefore provided by the additional compressor stage. This permits the air-conditioning system to be designed flexibly and the overall e~ciency optimized easily.
Due to the second compressor stage it is in particular possible to produce ice-free conditioned air. The invention exploits the fact that at a given temperature the amount of water condensing out of air increases with rising pressure. Since the tem-perature can only be influenced within limits due to the system, in particular because compressed engine air cooled in the main heat exchanger cannot be cooled below ambient temperature in the cooling shaft (designed for 38°C ambient temperature), a comparatively high compression pressure of >_ 4.6 bars can be produced with the additional compressor stage to reach the desired high degree of condensation in the high-pressure water extraction cycle. Freedom from ice is reached e.g. at -10°C and 1 bar with < 1.8 g of water per kilogram of dry air.
Instead of having a power source external to the system for the additional com-pressor, one can also operate the latter regeneratively by effecting not only compres-sion of bleed but also expansion of dehumidified air in two stages, for example in two separate turbines, and utilizing the energy delivered by the turbines for the first compressor stage, on the one hand, and for the second compressor stage, on the other. The air-conditioning system then comprises two machines each having at least a compressor wheel and a turbine wheel on a common shaft. Additionally the fan can be disposed on one shaft and a motor on the other shaft, whereby the motor can also be designed as a generator.
Disposing the compressor and turbine wheels on two separate shafts or in two separate machines permits much more flexible design of the overall system than conventional air-conditioning systems. One attains an optimum design in particular of compressor and turbine.
Freedom from ice can be obtained without any problem in particular when not only compression of bleed but also condensation of moisture contained in the air is effected in two stages in the high-pressure water extraction cycle. For this purpose a first condenser of the high-pressure water extraction cycle is disposed for heat ex-change with dehumidified air before the turbine inlet, in case of two-stage expansion before the second turbine inlet, and a second condenser of the high-pressure water extraction cycle for heat exchange with dehumidified and expanded air after the tur-bine outlet, compressed air being passed through said condensers in heat-exchanging fashion in order to condense water and then extract it. Effectiveness of dehumidifi-cation is increased substantially by two-stage condensation. This holds in particular when expansion is also effected in two turbine stages.
When small amounts of ice in the cooling air are no great problem and high ef ficiency of the overall system is important, it is advantageous to combine two-stage compression with two-stage expansion, compressed air being passed in heat-exchanging fashion through a condenser disposed between first and second turbines to extract moisture. Efficiency can be fiu~ther improved if dehumidified air is guided past compressed, not yet dehumidified air in heat-exchanging fashion in a reheater before entering the first turbine stage. This relieves the condenser, on the one hand, since compressed air is precooled before entering the condenser. On the other hand, any residual moisture contained in the dehumidified air is vaporized before the first turbine inlet so that the turbine surfaces are protected from being destroyed by water drops. In terms of efficiency this variant is to be ranked the most favorable.
The invention offers the further advantage that it is possible to switch off the additional compressor stage and optionally the turbine stage driving said compressor stage by means of suitable bypass circuits. This is useful in particular in flight op-eration, when air moisture and freedom from ice of the cooling air play no part so that high compression for the high-pressure water extraction cycle is unnecessary. In flight operation one can completely switch off one of the two machines by opening -and/or closing valves, thereby avoiding unnecessary losses and therefore increasing efficiency in flight operation.
Designing the air-conditioning system with two separate machines each com-prising compressor and turbine wheel on a common shaft, one of which can be switched off in flight operation, offers further advantages resulting from the fact that a greater pressure ratio is available in ground operation than in flight operation due to the system. This makes it energetically favorable to provide a relatively small tur-bine nozzle (baffle screen cross section) in ground operation. Said small nozzle is realized by connecting the two turbine stages in series, resulting in a "total nozzle"
smaller than each individual nozzle. In flight operation about the same volume flow is required for air-conditioning the airplane cabin despite a lower available pressure ratio, however, so that in flight operation a large nozzle would be necessary for about the same air flow. Since one machine and thus one turbine stage is turned off for the overall system in flight operation, a large nozzle results by reason of the sole remaining turbine of the second turbine stage for the overall system. One can thus increase efficiency in flight operation. This gain in efficiency is preferably utilized for designing the primary and main heat exchangers with minimal overall size and weight, under the constraint that the necessary volume flow rate is just met.
In the final effect one can thus achieve a smaller overall size and thus lower total weight of the air-conditioning system by the measure of providing two machines instead of only one machine.
A further advantage resulting when the air-conditioning system has two sepa-rate machines each with a coupled compressor and turbine is that if one machine fails at least the other machine still works and the air-conditioning system can be operated further without restriction. With the redundancy required for aircraft, this means that one fewer air conditioner or "pack" per aircraft is necessary, for example only two packs instead of three. As a consequence, the accordingly lower number of components decreases weight, increases the reliability of the installation and reduces expense for maintenance and repair.
Finally, it is to be ascertained that both in ground operation with two machines and in flight operation with one switched-off machine the energy gained during ex--g-pansion in the turbine or turbines is largely recovered via the two compressor stages (ground operation) or the sole remaining compressor stage (flight operation).
In the following the invention will be described by way of example with refer-ence to Figures 1 to 3, in which:
Figure 1 shows a diagram of an inventive air-conditioning system, Figure 2 shows a diagram of an improved embodiment of the system of Fig-ure 1, in particular for producing ice-free conditioned air, Figure 3 shows a diagram of an improved embodiment of the system of Fig-ure 1 with improved efficiency, and Figure 4 shows an air-conditioning system according to the prior art.
Figure 1 shows an air-conditioning system differing from the air-conditioning system described in Figure 4 with respect to the prior art substantially in that two compressors C1 and C2 are provided in order to bring bleed cooled in primary heat exchanger PHX to the pressure necessary for high-pressure water extraction.
Com-pressors C1 and C2 are to be designed depending on whether freedom from ice or high efficiency of the air-conditioning system is more important. In Figure 1, com-pressor C1 of the first compressor stage together with turbine T and fan F
form three-wheel machine ACM. That is, compressor C 1 and fan F are driven regenera-tively by energy gained in turbine T. Compressor C2 of the second compression stage is operated by separate motor M, i.e. by external energy. Check valve CYZ
opens automatically when compressor C2 is blocked or when motor M of compres-sor C2 is not switched off in flight operation for example. Check valve CVl opens automatically when air cycle machine ACM is blocked or bypass valve BPY2 is ac-tively opened.
The air-conditioning system schematically shown in Figure 1 otherwise corre-sponds fundamentally in structure and function to the system of Figure 4, whereby it should be taken into account that the reheater is not absolutely necessary but of great advantage in particular in case absolute freedom from ice is to be achieved.
Figure 2 shows a further development of the invention. In the air-conditioning system shown schematically therein, dehumidified air is expanded in two stages via turbines Tl and T2. Energy gained during expansion in turbine Tl is utilized regen-eratively to drive compressor C2, while energy delivered by turbine T2 is utilized regeneratively by compressor Cl, as before. In addition to condenser CONl in the high pressure dewatering cycle, through which condensed bleed is guided in heat-exchanging fashion past dehumidified air expanded in turbine Tl, second condenser CON2 is provided through which air precooled in condenser CONI is guided in heat-exchanging fashion past air expanded by turbine T2. Condensers CONI and CON2 are especially advantageous when conditioned air is to be free from ice.
Oth-erwise one can do without condenser CON2, which one does in particular when high efficiency of the overall system is to be achieved.
Before air expanded in the first turbine stage enters condenser CONl, water extractor WE2 is advantageously provided in addition to water extractor WEl pro-vided in the high-pressure water extraction cycle. Extracted water is supplied to ram-air heat exchangers MHXlPHX to be vaporized therein. Water extractor WE2 is ad-vantageous in particular when air cycle machine ACM is blocked, since the effec-tiveness of first water extractor WEl is greatly restricted here.
Further, one can open economy valve ECV to switch off the high-pressure wa-ter extraction cycle, which is useful in particular when air cycle machine ACM
fails and not enough pressure is available for energetically suitable utilization of the high-pressure water extraction cycle. Water extraction is then effected at low pressure by water extractor WE2. Condensers CONI and CONZ are inoperative in this case.
As in the air-conditioning system described above, one can switch off the ma-chine comprising turbine Tl and compressor C2 in particular for flight operation by opening bypass valve BPYI. By opening bypass valve BPY2 one can also bypass air cycle machine ACM, in particular if it fails.
Figure 2 shows optional motor M, with which the efficiency of the system can be optimized, by dotted lines on the shaft interconnecting turbine Tl and compressor C2. One can either make additional energy available to the system. Or, and in par-ticular, one can utilize the motor as a generator in order to supply surplus energy to the board wiring.
While the air-conditioning system shown in Figure 2 is in particular suitable for providing ice-free conditioned air, Figure 3 schematically shows an air-condi-tinning system having especially favorable e~ciency. As described with respect to Figure 4 (prior art), reheater REH is disposed before turbine Tl and condenser CON
after turbine Tl in heat-exchanging fashion for compressed air to flow through and for condensation of moisture contained therein. Reheater REH can fundamentally be omitted, but is advantageous for the reasons stated above. Moisture contained in compressed air is condensed in condenser CON at a comparatively high energy level, in contrast to the prior art described in Figure 4, whereby this energy can be utilized in turbine T2 as fundamentally proposed in US 5,086,622. However, in US
5,086,622 turbines Tl and T2 are disposed jointly with compressor C1 and fan F
on a common shaft in a single air cycle machine ACM. Since according to the invention compression is divided into two stages, and turbine Tl plus compressor C2 and tur-bine T2 plus compressor C1 each form separate machines, efficiency can be in-creased further because the design of the air-conditioning system is altogether more variable.
As described in Figure 2, economy valves ECVl and ECVZ serve optionally to bypass the high-pressure water extraction cycle. By opening bypass valve BPVl one bypasses the machine comprising turbine Tl and compressor C2 in flight operation.
Bypass valve BPY2 accordingly serves to bypass air cycle machine ACM if it fails.
Both bypass valves can also be used optionally as temperature control valves.
Tem-perature control valve TCV2 is likewise optional, while temperature control valve TCV4 should preferably be provided in the air-conditioning system. As mentioned above, one can actually omit reheater REH, but it is advantageous for the reasons stated at the outset.
Depending on the system requirement and/or to simplify the system, individual valves can be omitted, as mentioned above, or they can be partly combined. In par-ticular one can for example combine valves ECYI, BPVl and ECYZ into one line with only one valve, resulting in a less complex system altogether. The installation is then optimized for flight operation with a switched-off machine (turbine Tl/com-pressor C2).
Claims (22)
1. A method for conditioning moisture-containing, pressurized air for air-conditioning a passenger plane cabin comprising the following steps:
- compressing the pressurized air to a higher pressure, - dehumidifying the compressed air by condensing and extracting water from the compressed air, - expanding the dehumidified air to a lower pressure, thereby gaining process energy which is utilized regeneratively in the step of compressing the pressurized air to the higher pressure, and - passing on the conditioned air for air-conditioning the passenger plane cabin, characterized in that the step of compressing the pressurized air to a higher pressure is effected in separate first and second compression stages.
- compressing the pressurized air to a higher pressure, - dehumidifying the compressed air by condensing and extracting water from the compressed air, - expanding the dehumidified air to a lower pressure, thereby gaining process energy which is utilized regeneratively in the step of compressing the pressurized air to the higher pressure, and - passing on the conditioned air for air-conditioning the passenger plane cabin, characterized in that the step of compressing the pressurized air to a higher pressure is effected in separate first and second compression stages.
2. A method according to claim 1, wherein energy external to the process is supplied in the other of the two compression stages.
3. A method according to claim 1, wherein regenerated process energy is utilized in the other of the two compression stages.
4. A method according to claim 3, wherein expansion of the air is effected in two separate stages by means of first and second turbines, and the energy gained with the first turbine is utilized regeneratively at least partly in the second compression stage and the energy gained with the second turbine at least partly in the first compression stage, or vice versa.
5. A method according to claim 4, wherein water is extracted from the air after expansion of the air in the first turbine stage and before expansion of the air in the second turbine stage.
6. A method according to either of claims 4 and 5, wherein in the condensation step the compressed air is guided in heat-exchanging fashion past the air expanded by the first turbine stage, and cooled.
7. A method according to claim 6, wherein the condensation step is performed in two stages by the compressed air also being guided in heat-exchanging fashion past the air expanded by the second turbine stage, and cooled.
8. A method according to any of claims 1 to 7, wherein the air is guided in heat-exchanging fashion past the compressed, and heated, after dehumidification and before expansion.
9. A method according to any of claims 4 to 8, wherein at least part of the energy gained during expansion in one of the two turbine stages is converted into electric energy and removed.
10. A method according to any of claims 1 to 9, characterized in that at least part of the process energy gained during expansion of the dehumidified air is utilized to drive a fan (F).
11. An air-conditioning system for passenger plane cabins for conditioning moisture-containing, pressurized air for air-conditioning a passenger plane cabin comprising:
- a compressor device (C1, C2) for compressing the pressurized air to a higher pressure, - a condenser (CON; CON1, CON2) and following water extractor (WE;
WE1, WE2) for dehumidifying the compressed air, - an expansion device (T; T1, T2) for expanding the dehumidified air to a lower pressure, the expansion device comprising a first turbine (T; T1, T2) coupled with the compressor device (C1) for driving the same, and - an output line for passing on the conditioned air for air-conditioning the passenger plane cabin, characterized in that the compressor device (C1, C2) is of two-stage construction for further compressing the pressurized air and comprises first and second separately driven compressors (C1 and C2).
- a compressor device (C1, C2) for compressing the pressurized air to a higher pressure, - a condenser (CON; CON1, CON2) and following water extractor (WE;
WE1, WE2) for dehumidifying the compressed air, - an expansion device (T; T1, T2) for expanding the dehumidified air to a lower pressure, the expansion device comprising a first turbine (T; T1, T2) coupled with the compressor device (C1) for driving the same, and - an output line for passing on the conditioned air for air-conditioning the passenger plane cabin, characterized in that the compressor device (C1, C2) is of two-stage construction for further compressing the pressurized air and comprises first and second separately driven compressors (C1 and C2).
12. An air-conditioning system according to claim 11, wherein the other of the two compressors (C2) is driven with external energy (M).
13. An air-conditioning system according to claim 11, wherein the expansion device is of two-stage design and comprises a second turbine (T1) coupled with the other of the two compressors (C2) for driving the same.
14. An air-conditioning system according to claim 13, characterized in that a water extractor (WE2) is disposed between the two turbines (T1, T2).
15. An air-conditioning system according to either of claims 13 and 14, wherein a first heat exchanger (CON; CON1), through which the compressed air is passed in heat-exchanging fashion and cooled, is disposed between the two turbines (T1, T2).
16. An air-conditioning system according to claim 15, wherein a second heat exchanger (CON2), through which the compressed air is passed in heat-exchanging fashion and cooled, is disposed after the second turbine (T2).
17. An air-conditioning system according to any of claims 11 to 16, wherein a further heat exchanger (REH), through which the dehumidified air is passed and heated, is disposed before the first turbine.
18. An air-conditioning system according to any of claims 11 to 17, wherein a bypass device (CV2) is provided for bypassing the other of the two compressors (C2).
19. An air-conditioning system according to any of claims 13 to 18, wherein a bypass device (BPV1) is provided for bypassing the first turbine (T1).
20. An air-conditioning system according to any of claims 11 to 19, wherein a bypass device (CV1; BPV2) is provided for bypassing one of the two compressors (C1).
21. An air-conditioning system according to any of claims 11 to 20, wherein a generator (M) coupled with one of the two turbines (T1) and producing and removing energy is provided.
22. An air-conditioning system according to any of claims 11 to 21, wherein a fan (F) coupled with the other of the two turbines (T2) and driven thereby is provided.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19935918A DE19935918B4 (en) | 1999-07-30 | 1999-07-30 | Air conditioning system for aircraft cabins |
| DE19935918.0 | 1999-07-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2313788A1 true CA2313788A1 (en) | 2001-01-30 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002313788A Abandoned CA2313788A1 (en) | 1999-07-30 | 2000-07-12 | Air-conditioning system for airplane cabins |
Country Status (4)
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| CA (1) | CA2313788A1 (en) |
| DE (1) | DE19935918B4 (en) |
| FR (1) | FR2796918B1 (en) |
| GB (1) | GB2355520B (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10036443A1 (en) * | 2000-07-26 | 2002-04-04 | Liebherr Aerospace Gmbh | Air conditioning system for aircraft |
| US6257003B1 (en) * | 2000-08-04 | 2001-07-10 | Hamilton Sundstrand Corporation | Environmental control system utilizing two air cycle machines |
| DE10139483B4 (en) * | 2001-08-10 | 2005-06-23 | Liebherr-Aerospace Lindenberg Gmbh | Cooling system |
| US6526775B1 (en) * | 2001-09-14 | 2003-03-04 | The Boeing Company | Electric air conditioning system for an aircraft |
| DE10201426B8 (en) | 2002-01-16 | 2004-09-02 | Liebherr-Aerospace Lindenberg Gmbh | Cooling system |
| DE10201427A1 (en) * | 2002-01-16 | 2003-07-24 | Liebherr Aerospace Gmbh | Air dehumidification system in air conditioning systems |
| DE10247335B3 (en) | 2002-10-10 | 2004-04-08 | Liebherr-Aerospace Lindenberg Gmbh | Aircraft climate control system has a condenser unit with inlet and outlet for the recirculated air, inlet and outlet for the refrigerated air and a heat exchanger with a bypass |
| DE10301465B4 (en) * | 2003-01-16 | 2007-07-12 | Liebherr-Aerospace Lindenberg Gmbh | Cooling system |
| DE102005037285A1 (en) * | 2005-08-08 | 2007-02-15 | Liebherr-Aerospace Lindenberg Gmbh | Method for operating an aircraft air conditioning system |
| DE102006032979A1 (en) | 2006-07-17 | 2008-01-24 | Liebherr-Aerospace Lindenberg Gmbh | An aircraft air conditioning system and method for operating an aircraft air conditioning system |
| US10745136B2 (en) * | 2013-08-29 | 2020-08-18 | Hamilton Sunstrand Corporation | Environmental control system including a compressing device |
| CN103612760B (en) * | 2013-11-27 | 2016-08-17 | 中国航空工业集团公司西安飞机设计研究所 | A kind of closed air refrigerating circulatory device actively reclaiming cold |
| US11466904B2 (en) | 2014-11-25 | 2022-10-11 | Hamilton Sundstrand Corporation | Environmental control system utilizing cabin air to drive a power turbine of an air cycle machine and utilizing multiple mix points for recirculation air in accordance with pressure mode |
| US10549860B2 (en) * | 2014-11-25 | 2020-02-04 | Hamilton Sundstrand Corporation | Environmental control system utilizing cabin air to drive a power turbine of an air cycle machine |
| CN105526730B (en) * | 2016-01-14 | 2018-05-08 | 南京航空航天大学 | New two-wheeled high pressure water separation regenerative air cycle cooling system air circulation refrigeration system and refrigerating method |
| EP4019403B1 (en) | 2016-05-26 | 2024-07-03 | Hamilton Sundstrand Corporation | Mixing ram and bleed air in a dual entry turbine system |
| EP3825531B1 (en) | 2016-05-26 | 2023-05-03 | Hamilton Sundstrand Corporation | An energy flow of an advanced environmental control system |
| US11506121B2 (en) | 2016-05-26 | 2022-11-22 | Hamilton Sundstrand Corporation | Multiple nozzle configurations for a turbine of an environmental control system |
| US10604263B2 (en) * | 2016-05-26 | 2020-03-31 | Hamilton Sundstrand Corporation | Mixing bleed and ram air using a dual use turbine system |
| CN110816852B (en) * | 2019-11-27 | 2022-11-22 | 中国航空工业集团公司沈阳飞机设计研究所 | Differential pressure sensing type condenser anti-freezing and anti-blocking device and method |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB632678A (en) * | 1946-04-06 | 1949-11-28 | Garrett Corp | Cabin cooling system for aircraft |
| DE2834256C2 (en) * | 1978-08-04 | 1985-05-23 | Messerschmitt-Bölkow-Blohm GmbH, 8012 Ottobrunn | Arrangement for air conditioning of aircraft cabins |
| US4352273A (en) * | 1979-05-22 | 1982-10-05 | The Garrett Corporation | Fluid conditioning apparatus and system |
| US4550573A (en) * | 1983-12-12 | 1985-11-05 | United Technologies Corporation | Multiple load, high efficiency air cycle air conditioning system |
| GB2242261B (en) * | 1990-03-24 | 1993-11-24 | Aisin Seiki | Exhaust driven air cycle air conditioner |
| US5086622A (en) * | 1990-08-17 | 1992-02-11 | United Technologies Corporation | Environmental control system condensing cycle |
| JP3218688B2 (en) * | 1992-05-28 | 2001-10-15 | 株式会社島津製作所 | Air conditioner |
| US5442905A (en) * | 1994-04-08 | 1995-08-22 | Alliedsignal Inc. | Integrated power and cooling environmental control system |
| GB9407633D0 (en) * | 1994-04-18 | 1994-06-08 | Normalair Garrett Ltd | Air cycle cooling systems |
| US5967461A (en) * | 1997-07-02 | 1999-10-19 | Mcdonnell Douglas Corp. | High efficiency environmental control systems and methods |
| US5921093A (en) * | 1997-07-11 | 1999-07-13 | Alliedsignal Inc. | Air cycle environmental control system with energy regenerative high pressure water condensation and extraction |
| US5924293A (en) * | 1997-07-11 | 1999-07-20 | Alliedsignal Inc. | Air cycle environmental control system with fully energy regenerative high pressure water condensation and extraction |
| US5887445A (en) * | 1997-11-11 | 1999-03-30 | Alliedsignal Inc. | Two spool environmental control system |
| US6128909A (en) * | 1998-06-04 | 2000-10-10 | Alliedsignal Inc. | Air cycle environmental control systems with two stage compression and expansion and separate ambient air fan |
-
1999
- 1999-07-30 DE DE19935918A patent/DE19935918B4/en not_active Expired - Fee Related
-
2000
- 2000-07-10 GB GB0016940A patent/GB2355520B/en not_active Expired - Fee Related
- 2000-07-12 CA CA002313788A patent/CA2313788A1/en not_active Abandoned
- 2000-07-26 FR FR0009770A patent/FR2796918B1/en not_active Expired - Fee Related
Also Published As
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| DE19935918B4 (en) | 2006-08-31 |
| DE19935918A1 (en) | 2001-02-08 |
| GB2355520A (en) | 2001-04-25 |
| FR2796918B1 (en) | 2005-01-14 |
| GB0016940D0 (en) | 2000-08-30 |
| FR2796918A1 (en) | 2001-02-02 |
| GB2355520B (en) | 2003-09-03 |
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