FR2486210A1 - AIR CYCLE AIR CONDITIONING SYSTEM - Google Patents

Abstract

AIR CONDITIONING SYSTEM, ESPECIALLY FOR AIRCRAFT CABINS. SUPPLY AIR IS PROVIDED BY A COMPRESSOR 13 TO A EXPANSION TURBINE 12, WHERE IT IS COOLED, THEN TO A CABIN 19. THE WATER CONTAINED IN THE PRESSURIZED AIR BEFORE THE TURBINE 12 IS EXTRACTED BY AN EXTRACTOR 16 AND SPRAYED AT THE INLET OF A HEAT EXCHANGER 15 IN THE AIR FROM THE CABIN 19. THIS PROVISION INCREASES THE COOLING CAPACITY OF AIR CONDITIONING SYSTEMS FOR AIRCRAFT.

Description

Air conditioning system with air duct.

  The present invention relates to conditioning systems

Air cycle air.

  Air cycle air conditioning systems are used extensively on aircraft and they produce cooling of a suitable air supply,

  high temperature, by relaxing this air through

  to a turbine and through heat transfer to one or more heat exchangers. However, it is still sought to achieve air conditioning systems having a greater cooling capacity for unabated consumption of the supply air taken from aircraft engines. It is well known that when air is expanded through a turbine, its temperature is lowered and temperatures below 00C can be achieved. It is also well known that, as a result of variations in the moisture content of the supply air, which generally originates from the atmosphere, it may or may not form ice at the outlet of the turbine. function of atmospheric conditions

  ruling; consequently, so as to avoid a bad

  of the turbine system, because of the formation of ice, it is often expected that the temperature of the air supplied by the turbine is substantially at a temperature of 0C, or alternatively, the formation of ice is prevented by heating the output members of the turbine, to prevent ice accumulation on these bodies. It is also common practice, in these air conditioning systems,

  to provide an extraction of the water contained in the air of

  or in the air drawn from the engines, so as to establish conditions which are less favorable to the formation of ice. It is also known that by a water spray in

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  cooling air, at the inlet of a heat exchanger, a more efficient heat extraction of the air charge is achieved.This is why, in many air conditioning systems with a In the known air, the water that is extracted from the supply air is injected into the dynamic cooling air of the pre-coolers and the heat exchangers.

  primary to cool the supply air.

  Recent improvements have resulted in improved water extraction in such systems through the use of extraction means, referred to as high-pressure water separators, which condense water.

  upstream of the turbine inlet, at a location where the air

  The system is at the highest pressure in the system, which makes it possible to take advantage of the higher dew point temperature. In these separation means, an exchanger-condenser is arranged to receive the air which is conveyed to an expansion turbine as a fluid passing through the main channel of the exchanger and then to pass the same air as a fluid cooling after delivery by the turbine. Such an arrangement leads to a temperature substantially lower than 00C. at the outlet of the turbine, but because not all of the water is extracted, the temperatures at the condenser outlet are normally limited to about -10 ° C. If, after work, the air leaves the system

  at a temperature of, for example, 500C, the cooling gain

  from the use of air supplied at -100C is low when compared to conventional systems in which this

  air is kept just above 00C.

  However, in the systems known hitherto, water has never been used in the most efficient manner.

  extracted, because the latent heat of evaporation is not used.

to its full potential.

  The present invention makes it possible to provide an air cycle air conditioning system in which an additional cooling gain is achieved by efficient use of the water extracted from the high pressure supply air.

  The invention also aims to obtain a cooling effect

  additionally in an air cycle air conditioning system by substantially utilizing the total potential of the latent heat of evaporation of the water extracted from a feed

high pressure air.

  The subject of the invention is an air cycle air conditioning system I0, comprising an expansion turbine which provides a relaxed air flow for conditioning a load.

  characterized in that it comprises extraction means

  water supply of the high pressure supply air upstream of the expansion turbine, and means for injecting the extracted water I5 into the inlet of the cooling fluid of a heat exchanger which receives the flow. of supply air expanded from the turbine after this air has removed heat from said

thermal load.

  According to one embodiment of the invention, pre-cooled air passes through a compressor, mounted on the same shaft as the expansion turbine, and then arrives at the inlet of the turbine after being passed through the main airway. the heat exchanger in which this air is cooled by the flow of the supply air expanded by the turbine, after this air has extracted from the heat of a heat load the water extracted from the feed of high pressure air,

  upstream of the inlet of the turbine being injected into the feed

  air expelled by the turbine at the moment this air enters the coolant inlet of the heat exchanger.

heat.

  In this system, the latent heat of evaporation of the extracted water is used to condense the water contained in the high-pressure air supplied by the compressor to the turbine, 4.

  which makes it possible to obtain substantially equivalent performances

  slow to those obtained with dry air, in the range of

ambient humidities.

  According to another embodiment of the invention, the feed air stream expanded by the turbine, after extracting heat from a heat load such as a compartment or an aircraft cabin, passes through the heat exchanger so as to be in temperature exchange relationship with fluid flowing in a separate loop, to cool another heat load, according to this embodiment, the water extracted from the feed air under high pressure upstream of the inlet of the turbine is injected into the supply air expanded by the turbine when this air enters the inlet of the cooling fluid of

the heat exchanger.

  Known packaging systems comprise means for extracting water from the air under high pressure upstream of the inlet of the turbine, the extracted water being injected into the inlet of the cooling fluid of a heat exchanger.

  dynamic air heat, so that the efficiency of evaporation

  water is normally limited by the high ratio of

  flow rates of the coolant and the charge to be cooled.

  The present invention provides, on the contrary, a system in which the two mass flow rates, through the heat exchanger into which the extracted water is injected, are the same thanks to which the optimum characteristics of heat transfer by pulling are obtained. the best of heat

  latent evaporation of the extracted water.

  The invention will be better understood on reading the

  detailed description which will follow and on the examination of the drawings which show by way of nonlimiting examples several modes

embodiment of the invention.

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  Figure 1 is a schematic representation of an embodiment of an air conditioning system according to the invention. Figure 2 is a schematic representation of another embodiment of the invention. The air cycle air conditioning system 10,

  shown in FIG. 1, comprises a turbocompres-

  11 is a loop-mounted circuit comprising a cold air expansion turbine 12 operably coupled to a radial compressor 10 via fluid conduits 14 and a common shaft. The conduit line 14 conveys air from the compressor 13 to the turbine 12 via the main heat exchanger channel and a vortex water extractor 16. The extractor water pump I5 16 is connected with an injector device 17 which is arranged to spray water into the inlet of the cooling fluid path of the heat exchanger 15, this water coming from the separator cover 16. The compressor 13 receives a supply of pressurized air, through a pre-cooling exchanger 18, from an air source such as the high pressure stage or the intermediate stage of a turbo engine. The turbine outlet 12 is connected to the inlet of a compartment or a

  cabin 19, through the cooling fluid passageway

  a heat exchanger 20, or charge exchanger

  thermal, this passageway being part of a circuit 21.

  A pipe 22, intended for the evacuation from the compartment 19 of the supply air expanded by the turbine, is connected to the passageway of the cooling fluid of the loop heat exchanger 15, beyond which this air is evacuated outside. The main path of the heat exchanger 20 is part of a closed circulation circuit which comprises a heat load 23 such as a compartment for electronic equipment. The fluid in this circuit may be gaseous or liquid and is circulated by a fan or pump 24, as the case may be. The circuit 21, when connected to a cabin 19, preferably includes a flow inducing device 25 for recycling a portion of the cabin air. When the system 10 is in operation, pressurized air is supplied from the unrepresented air source, and is cooled through the precooler 18 before entering the loop-mounted turbo compressor assembly 11. , from which it is relaxed to reach temperatures below 0, for example -50 to -600C, before

  to enter the exchanger 20 of the heat load.

  This heat exchanger produces considerable heat transfer by dissipating the heat of the heat load 23, so that the temperature of the supply air expanded by the turbine can be of the order of 0 ° C to 100C, so that this air, when brought to a cabin 19, needs to see its temperature again raised to a

  level acceptable by passengers. This increase in temperature

  ture is achieved by recycling a portion of the cabin air that is driven by the flow inducing device

  disposed upstream of the entrance of the cabin.

  The supply air expanded by the turbine, after having been evacuated from the cabin 19, is conveyed via line 22 to the heat exchanger 15 in which it plays the role of cooling fluid vis-à- supply air screw

  at high pressure which is provided by the compressor 13. The efficiency

  cited heat transfer of this arrangement is increased

  by spraying in the relaxed air, at the inlet of the cooling fluid

  of the heat exchanger 15, all of the water which has been previously extracted from the high-pressure supply air by the water separator 16. Since substantially all of the water is extracted from the supply air, then returned to it, the most efficient use

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  latent heat for the evaporation of water is permitted, which leads to performance substantially equivalent to that which could be achieved with dry air, throughout the range of ambient humidity. This fact, together with the use of air at a temperature substantially lower than 0 as a cooling agent, reduces the need

  in air taken from the engines of the aircraft.

  The air conditioning system 30 which is shown

  Figure 2 is a variant of the one just described.

  It provides better self-regulation and has an inherent ability to adjust itself according to

  humidity conditions of the supply air under pressure.

  The system 30 includes a loop-mounted turbocharger / heat exchanger assembly 31. This assembly comprises an I5 air expansion turbine 32 and a radial compressor 33 which are mounted on a common shaft, the compressor outlet being connected to the inlet of the turbine via a circuit 34. This circuit 34 includes, downstream, the main routes of an aftercooler 35, a

  regenerating exchanger 36, a heater 37, a heat exchanger

  condenser 38 and includes the coolant path of the heater 37. A conduit 39 connects the compressor inlet to a source of pressurized air (not shown), such as an air sample from an aircraft engine. , through

a pre-cooler 40.

  The outlet of the turbine 32 is connected by a circuit 41 to the coolant condenser 38 and a heat exchanger 42 and then to a plurality of compartments which may comprise a cabin 43 and two equipment compartments 44, 45, after which the air is discharged to the outside after having passed through the passages for cooling fluids of a heat exchanger 46 and the heat exchanger

generator 36.

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  One of the equipment compartment 45 is connected to a branch line 4la connected in parallel with the cabin 43

and the compartment 44.

  A water extractor 47, preferably of the vortex fixed vane type, is included in the circuit 34, at the outlet of the condenser 38, and is connected by a pipe 48 to an injector device 49 which sprays water into the inlet of the cooling fluid passage of the heat exchanger 46. The main channels of the exchangers 42 and 46 are part of a closed recycle cooling circuit 50

  which comprises a heat load 51. The cooling fluid

  in the circuit 50 can be gaseous or liquid and is circulated by a fan or a pump 52,

  as the case may be. Pre-cooling coolant

  I5 40 and the intercooler 35 can be derived

  any appropriate source and, in the case of

  cations, this coolant is supplied

by dynamic air.

  We will now describe the functioning of the system

  shown in Figure 2 when applied to an aircraft.

  Pressurized supply air is supplied under a

  pressure, at the compressor inlet 33, through the

  intermediate 39 and precooler 40.

  In a manner that is conventional with loop circuit systems, the supply air temperature is high during compression, and then this air is cooled during its operation.

  passing through the circuit 34. In the intermediate cooler

  diaire 35, the cooling is advantageously provided by dynamic air; in the regenerator exchanger 3.6 cooling is provided by the supply air which is continuously discharged out of the system-30, while in the heat exchanger 37 is transferred from an air zone of supply located upstream of the condenser 38

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  to an area below the latter, thanks to which this air is

  warmed before entering the turbine or it is complete

  relaxed. Condensates are extracted from the air

  at the outlet of the condenser by the water extractor 47.

  In high humidity conditons, the temperature of the expanded supply air discharged from the condenser 38 will not be substantially below the freezing point, for example -100C, as a result of the condensation effect of the water in the air; while in low humidity conditions, this temperature will be substantially lower, for example - 40 C, due to the lower requirements of condensation. This exhaust air, expanded by the turbine, circulates, as a cooling fluid, through the heat exchanger 42 in which it collects heat from the cooling fluid of the closed circuit 50 before being transferred to the cabin 43, to the compartment 44 and, under the control of a temperature system control (not shown) to the compartment 45 through the branch line 41a. The expanded air of the turbine after evacuation from the cabin 43 and the compartments 44, 45 is brought, as a cooling fluid, to the heat exchanger 46 in the inlet of which the injector

  49 sprays the water extracted by the water extractor 47.

  The amount of this water increases when atmospheric humidity

  that increases and, consequently, the cooling effect on the charge to be treated, that is to say on the fluid flowing in the cooling circuit 50, increases, so that under conditions of high humidity, the totality of the injected water is not evaporated in the heat exchanger 46. The water, which is thus not evaporated, is entrained in the passage of the cooling fluid of the regenerative exchanger 36 of the turbo compressor assembly 31, where it is then evaporated before the expanded air leaves the conditioning system / 9.

24862 1 C

  The fluid in the closed cooling circuit 50 is circulated by the fan or the pump 52, whereby the heat that is generated in the heat load 51 is dissipated by transfer to the air expanded by the turbine under the effect heat exchangers 42 and 46. Thus, for a feed air having a high humidity, an appreciable proportion of the cooling capacity is produced by evaporation of water in the heat exchanger 46, while under conditions of low humidity an appreciable proportion of cooling is provided by

  dry cold air in the heat exchanger 42.

  Under conditions of high humidity, the evaporation is not complete in the exchanger 46 and final evaporation occurs in the regenerative exchanger 36, which gives it a greater cooling capacity and which consequently, a higher condensation rate in the condenser 38. Therefore, the supply air flow to the turbine 32 can be maintained in a sufficiently dry state to allow temperatures to be obtained.

  substantially less than 00C at the outlet of the turbine.

  Known temperature control means (not shown) are incorporated in the system so as to regulate the variable conditions, as well as the conditioning requests made to it during operation, so as to

  maintain the most efficient operating conditions.

  It appears from the above description that

  that the efficiency of the already known systems can be increased by a more efficient use of the latent heat of evaporation, by returning all the water extracted from the supply air in a zone of high pressure of the sytem towards the same air in an area where it provides a cooling function. It appears

  also that by allowing the use of air at a temperature of

  significantly lower than QOC as a cooling agent, the supply air requirements from a turbine engine can be reduced for

  given cooling of the system.

  Of course, the invention is not limited to the embodiments described and shown, it is susceptible to many variants accessible to those skilled in the art

  without departing from the scope of the invention.

  It is thus possible to include in the system various flow control means, such as variable nozzle turbines Io, as well as different arrangements of

  shunt circuits to balance the cooling capacity

  the system to various thermal loads.

12.

Claims (6)

  An air cycle air conduction system, comprising an expansion turbine (12) which provides a relaxed air flow for conditioning a thermal load (19-23), characterized in that it comprises means for extracting water (16) from the high pressure supply air upstream of the expansion turbine, and means (17) for injecting the extracted water into the cooling fluid inlet of a heat exchanger (15) which receives the flow of supply air I0 expanded from the turbine after this air has subtracted from the heat at said thermal load.   2. System according to claim 1, characterized in that the heat exchanger (15) is arranged to be in heat exchange relation with the high-pressure air supply flowing from a compressor (13). ) around the expansion turbine (12).   3. System according to claim 2, characterized in that the thermal load comprises a compartment (19) to which circulates the supply air expanded by the turbine (12) for conditioning purposes, through the channel of the cooling fluid in a heat-exchanger heat exchanger (20) which is arranged to be in heat exchange relation with a fluid circulating in a closed circuit which   has another heat load (23).   4. System according to claim 1, characterized in   the heat exchanger (15) is arranged to be in relation to   heat exchange with a fluid circulating in a circuit   in a loop to cool another heat load (23).   5. System according to claim 4, characterized in that the water extraction means (47) are arranged downstream of a heat exchanger-condenser (38) in a circuit connecting the output   a radial compressor (33) with the inlet of the expansion turbine. 13 2486210   6. System according to Claim 5, characterized   in that the aforementioned circuit comprises an exchanger-regenerator   (46) connected to the outlet of the cooling path of the heat exchanger (46) to receive the expanded supply air flow supplied by the turbine from the cooling channel of the heat exchanger. the exchanger (46) after injection of extracted water.