Patent Publication Number: US-2022235973-A1

Title: Air conditioning system with integrated water extraction loop

Description:
TECHNICAL FIELD OF THE INVENTION 
     The invention relates to an air conditioning system for an aircraft. In particular, the invention relates to an air conditioning system comprising an optimized water extraction loop. 
     Technological Background 
     In an aircraft, an air conditioning system makes it possible to treat the air that is intended in particular for supplying the cabin of the aircraft. Throughout the text, the term “cabin” denotes any interior space of an aircraft in which the pressure and/or temperature of the air needs to be controlled. This may be a cabin for passengers, the pilot&#39;s cockpit, a hold, and in general any area of the aircraft that requires air at a controlled pressure and/or temperature. 
     Air treatment consists in particular in adjusting the temperature, pressure, humidity, etc., of air from an air source of the aircraft, for example by bleeding air from the propulsion engines of the aircraft, this air usually being referred to as bleed air. This air source can also be external ram air which is treated by various devices to bring it to a temperature and pressure compatible with the requirements of the cabin. 
     Conventional air conditioning systems comprise a pneumatic turbine engine that comprises at least one compressor and at least one turbine and is interconnected by a mechanical shaft such that the compressor and the turbine are driven together. 
     The turbine of the turbine engine is generally associated with an assembly referred to using the term “water extraction loop,” which comprises at least two heat exchangers—a first heat exchanger referred to using the term “heater” and a second heat exchanger referred to using the term “condenser”—and a water extractor, which is also referred to using the term “water separator.” 
     The extraction loop is intended for drying the air before it is injected into the turbine of the air cycle turbine engine in order to be expanded and distributed to a mixing chamber connected to the cabin of the aircraft. 
     The thermodynamic performance of an air conditioning system (also referred to using the term air conditioning pack) is linked to the water extraction performance of the water extraction loop. In addition, a high-performance water extraction loop makes it possible to increase the reliability of the conditioning pack by preventing erosion of the turbine. 
       FIG. 1  schematically shows a water extraction loop and a turbine of an air cycle turbine engine according to an embodiment commonly used on aircraft. 
     The water extraction loop comprises a heater  10 , a condenser  12 , and a water separator  14 . Air  16  supplied by the air conditioning system successively passes through the heater  10  and condenser  12  as a hot pass. The air  18  leaving the condenser passes through the water separator  14 , which recovers the water  20  that can be used in the air conditioning system (for example that can be injected into a cooling ram air channel). 
     The dried air  22  leaving the water separator  14  passes through the heater  10  as a cold pass. 
     The air  24  leaving the heater is led to the inlet of the turbine  26  of the air conditioning system. At the outlet of the turbine  26 , the air  28  passes through the condenser  12  as a cold pass and the air  30  leaving the condenser is conveyed to the cabin of the aircraft (after possibly passing through a mixing chamber). 
     The turbine  26  generally forms part of an air cycle turbine engine comprising a turbine engine shaft  31  on which the turbine  26  and a compressor  34  are secured. The turbine  26  allows energy recovery to drive the compressor  34 , which compresses air from the air conditioning system upstream of turbine  26 . The shaft  31 , the turbine  26  and the compressor  34  are configured to rotate about an axis  32  of the turbine engine. The air  16  comes from the compressor  34  and may have been subjected to various treatments, for example passing through a main-exchanger-type exchanger in order to be cooled by ram air. 
     A water extraction loop is therefore an essential but bulky element of current air conditioning systems. In particular, it is necessary to have a particular number of pipes in order to fluidically connect the heater, the condenser, the water separator, and the turbine of the air cycle turbine engine. 
     Insofar as the space available on board aircraft that is reserved for air conditioning systems is increasingly reduced, inventors have sought to provide a new water extraction loop design that makes it possible to reduce its impact in terms of overall size while maximizing its performance. 
     Aims of the Invention 
     The invention aims to provide a more compact air conditioning system. 
     The invention aims in particular to provide an air conditioning system having a water extraction loop that has a limited overall size compared with known solutions. 
     The invention also aims to provide, in at least one embodiment, an air conditioning system comprising a more compact, more integrated, and more efficient water extraction loop than in the known systems. 
     The invention also aims to provide, in at least one embodiment, an air conditioning system comprising a water extraction loop that can be manufactured by additive manufacturing. 
     The invention also aims to provide an air conditioning system compatible with aeronautical, rail, and automobile applications. 
     Finally, the invention aims to provide a transport vehicle such as an aircraft that is equipped with an air conditioning system according to the invention. 
     DISCLOSURE OF THE INVENTION 
     To this end, the invention relates to an air conditioning system for a cabin of an air or rail transport vehicle, comprising:
         a pneumatic turbine engine that comprises at least one compressor and at least one turbine and is connected by a mechanical shaft extending along an axis, referred to as the turbine engine axis, said turbine comprising an air inlet and an air outlet; and   a water extraction loop that comprises a heater, a condenser and a water separator, is fluidically arranged between an air outlet of the compressor and the air inlet of said turbine, and is configured to be able to dry the air supplied to said turbine.       

     An air conditioning system according to the invention is characterized in that:
         said heater, said condenser and said water separator are arranged in series, forming the air inlet of said turbine;   said heater is arranged on the turbine engine axis or around said axis;   said condenser is arranged on the turbine engine axis or around said axis; and   said water separator is arranged on the turbine engine axis or around said axis.       

     An air conditioning system according to the invention therefore makes it possible to significantly reduce the overall size of the water extraction loop by arranging the heater, the condenser and the water separator on or around the turbine engine axis. 
     The arrangement in series of the elements of the heater, the condenser and the water separator is understood from a fluidic point of view, the fluid leaving the compressor passing, in sequence, first through the heater, then the condenser, and finally the water separator. 
     In addition, the performance of the water extraction loop is improved by the proximity of the elements to each other, and the proximity to the turbine, in particular due to the reduction in pressure drops. 
     The invention makes it possible to integrate the functions of the heater, the condenser and the water separator on the turbine engine axis or in an annular manner around said axis. 
     Preferably, the various components of the water extraction loop are each annular or cylindrical in order to be able to be integrated around the axis of the turbine engine and/or have rotational symmetry along the axis of the turbine engine. 
     Advantageously and according to the invention, the heater is selected from the following alternatives:
         a cross-flow heat exchanger, in which a first flow formed by a cold air pass and a second flow formed by a hot air pass cross;   a co-current flow heat exchanger, in which a first flow formed by a cold air pass and a second flow formed by a hot air pass are parallel and in the same direction; and   a counter-current flow heat exchanger, in which a first flow formed by a cold air pass and a second flow formed by a hot air pass are parallel and in opposite directions.       

     According to this aspect of the invention, the heater can take different forms depending on the desired performance, the tolerated pressure drops, the configuration of the air conditioning system, the devices adjoining the air conditioning system when said system is integrated into a vehicle, etc. 
     Advantageously and according to the invention, the condenser is selected from the following alternatives:
         a cross-flow heat exchanger, in which a first flow formed by a cold air pass and a second flow formed by a hot air pass cross;   a co-current flow heat exchanger, in which a first flow formed by a cold air pass and a second flow formed by a hot air pass are parallel and in the same direction; and   a counter-current flow heat exchanger, in which a first flow formed by a cold air pass and a second flow formed by a hot air pass are parallel and in opposite directions.       

     According to this aspect of the invention, the condenser can take different forms depending on the desired performance, the tolerated pressure drops, the configuration of the air conditioning system, the devices adjoining the air conditioning system when said system is integrated into a vehicle, etc. 
     Advantageously and according to the invention, the condenser is arranged such that an inlet of a cold air pass of the condenser is in the axis of the turbine engine, opposite the air outlet of the turbine. 
     According to this aspect of the invention, the condenser directly receives the air leaving the turbine to form the cold air pass. The cold air pass makes it possible to cool the hot air pass of the condenser, after passing through the heater and before passing through the water separator. 
     Advantageously and according to the invention, the water separator is formed of at least two water sub-separators, each water sub-separator being directly integrated into the condenser at an outlet of a hot air pass of said condenser. 
     According to this aspect of the invention, the water separator is directly integrated into the outlet of the condenser, allowing an improvement in compactness and a reduction in pressure drops. 
     The invention also relates to an air or rail transport vehicle, comprising a cabin configured to be supplied with conditioned air, characterized in that said vehicle comprises an air conditioning system according to the invention which is configured to supply conditioned air to the cabin. 
     The invention also relates to an air conditioning system and a transport vehicle that are characterized in combination by all or some of the features mentioned above or below. 
    
    
     
       LIST OF FIGURES 
       Further aims, features and advantages of the invention can be found in the following description, which is provided solely as a non-limiting example, and which refers to the accompanying figures, in which: 
         FIG. 1  is a schematic view of a water extraction loop according to the prior art, which loop has already been described; 
         FIG. 2  is a sectional schematic view of an air conditioning system according to a first embodiment of the invention; 
         FIG. 3  is a sectional schematic view of an air conditioning system according to a second embodiment of the invention; 
         FIG. 4  is a sectional schematic view of an air conditioning system according to a third embodiment of the invention; and 
         FIG. 5  is a sectional schematic view of an air conditioning system according to a fourth embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION 
     For the sake of illustration and clarity, the drawings do not strictly adhere to scales and proportions. 
     Moreover, identical, similar, or analogous elements are denoted by the same reference signs throughout the figures. 
       FIG. 1  (already described) illustrates the general operating principle of a water extraction loop. The various embodiments described below follow this operating principle with regard to the elements making up the water extraction loop, the air flow of the air conditioning circuit, and the various stages of the passage of this air flow through the various elements of the water extraction loop. 
       FIGS. 2 to 5  show four embodiments of the invention in which the heater, the condenser and the water separator of the water extraction loop are arranged in series on the axis, or around said axis, of a turbine engine that comprises a compressor and a turbine, forming the air inlet of said turbine. 
     The figures show the turbine and the water extraction loop in section along a plane including the axis of the turbine engine. 
     The invention therefore makes it possible, in all these embodiments, to provide a compact and well-integrated water extraction loop around the turbine. 
     The air extraction loop is supplied, in all the embodiments, by a source  50  of air which circulates in the air conditioning system and in particular comes from an outlet of a main heat exchanger of a conventional air conditioning system. 
       FIG. 2  shows a first embodiment of the invention, in which:
         the heater  110  is what is referred to as a cross-flow heat exchanger, that is to say that the air flow  116  forming the hot pass of the heater and the air flow  122  forming the cold pass of the heater cross, for example are substantially perpendicular or at another angle, preferably between 45° and 90°;   the heater  110  is cylindrical and surrounds the axis  132  of the turbine engine and the turbine  126  such that the outlet of the cold pass of the heater leads directly into the air inlet of the turbine  126 ;   the condenser  112  is what is referred to as a cross-flow heat exchanger, that is to say that the air flow  116  forming the hot pass of the condenser and the air flow  128  forming the cold pass of the condenser cross, for example are substantially perpendicular or at another angle, preferably between 45° and 90°;   the condenser  112  is cylindrical, surrounds the turbine engine axis  132 , and leads directly into the separator  114 ; and   the water separator  114 , supplied directly by the condenser  112  (that is to say without piping between the condenser and the water separator), also surrounds the axis  132  of the turbine engine.       

       FIG. 3  shows a second embodiment of the invention, in which:
         the heater  210  is what is referred to as a cross-flow heat exchanger, that is to say that the air flow  216  forming the hot pass of the heater and the air flow  228  forming the cold pass of the heater cross, for example are substantially perpendicular or at another angle, preferably between 45° and 90°;   the heater  210  is cylindrical and surrounds the axis  232  of the turbine engine and the turbine  226  such that the outlet of the cold pass of the heater leads directly into the air inlet of the turbine;   the condenser  212  is what is referred to as a co-current flow heat exchanger, that is to say that the air flow  216  forming the hot pass of the condenser and the air flow  222  forming the cold pass of the condenser are substantially parallel and flow in the same direction;   the condenser  212  is cylindrical and surrounds the axis  232  of the turbine engine; the outlet of the turbine leads directly into the inlet of the cold pass of the condenser  212 , which inlet is arranged in the axis of the turbine engine, and the outlet of the condenser  212  leads directly into the water separator  214 ; and   the water separator  214 , supplied directly by the condenser  212  (that is to say without piping between the condenser and the water separator), surrounds the axis  232  of the turbine engine.       

       FIG. 4  shows a third embodiment of the invention, in which:
         the heater  310  is what is referred to as a counter-current flow heat exchanger, that is to say that the air flow  316  forming the hot pass of the heater and the air flow  328  forming the cold pass of the heater are substantially parallel and flow in opposite directions;   the heater  310  is cylindrical and surrounds the axis  332  of the turbine engine and the turbine  326  such that the outlet of the cold pass of the heater leads directly into the air inlet of the turbine;   the condenser  312  is what is referred to as a cross-flow heat exchanger, that is to say that the air flow  316  forming the hot pass of the condenser and the air flow  328  forming the cold pass of the condenser cross, for example are substantially perpendicular or at another angle, preferably between 45° and  90 ′;   the condenser  312  surrounds the turbine engine axis; the inlet to the cold pass of the condenser  212  is supplied directly by the outlet of the turbine (that is to say without piping between the outlet of the turbine and the inlet of the cold pass of the condenser) and is arranged in the axis  332  of the turbine engine;   the condenser  312  is a dual condenser, that is to say that each hot pass passes through the entire condenser  312  in a direction perpendicular to the axis of the turbine engine; and   the water separator  314  surrounds the axis  332  of the turbine engine.       

       FIG. 5  shows a fourth embodiment of the invention, in which:
         the heater  410  is what is referred to as a counter-current flow heat exchanger, that is to say that the air flow  416  forming the hot pass of the heater and the air flow  428  forming the cold pass of the heater are substantially parallel and flow in opposite directions;   the heater  410  is cylindrical and surrounds the axis  432  of the turbine engine and the turbine  426  such that the outlet of the cold pass of the heater leads directly into the air inlet of the turbine;   the condenser  412  is what is referred to as a U-flow heat exchanger, that is to say that the air flow  416  forming the hot pass of the condenser and the air flow  428  forming the cold pass of the condenser are substantially parallel, and the air flow  416  forming the hot pass flows successively in the same direction as and then in a direction opposite to the air flow  428  forming the cold pass of the condenser;   the condenser  412  surrounds the axis  432  of the turbine engine; the inlet of the cold pass of the condenser  412  is supplied directly by the outlet of the turbine (that is to say without piping between the outlet of the turbine and the inlet of the condenser) and is arranged in the axis of the turbine engine; and   the water separator consists of a plurality of water sub-separators  414   a ,  414   b , each being integrated into a hot pass outlet of the condenser  412 , the sub-separators  414   a ,  414   b  being arranged all around the axis  432  of the turbine engine.       

     The invention is not limited to the embodiments shown; different types of heater, condenser and water separator can be used in different configurations that are not shown but are compatible with the desired operation. In general, the invention can be implemented by any design which makes it possible to integrate the functions of the heater, the condenser and the water separator on the turbine engine axis or in an annular manner around said axis, so as to limit the overall size of the air conditioning pack and improve performance of the water extraction loop by limiting pressure drops.