HEAT EXCHANGER ASSEMBLY WITH AN INSULATING AIR GAP AND ASSOCIATED AIR CONDITIONING SYSTEM

Description

Technical field of the invention

[0001] The invention relates to an assembly of heat exchangers. In particular, the invention relates to an assembly of heat exchangers that can be used in an aircraft air conditioning system. Technological background

[0002] Air conditioning systems or other systems based on a plurality of heat exchanges between different fluids include a plurality of heat exchangers enabling these heat exchanges.

[0003] In particular, in an aircraft air conditioning system, several heat exchangers can be used to cool fluids such as oil, air, etc., using ram air, often called "RAM air," which is typically ambient air drawn from outside the aircraft and set in motion by a fan. The fan is driven, for example, by a motor or by the shaft of a turbomachine, specifically by the shaft of a turbomachine in the air conditioning system.

[0004] This dynamic air source allows for efficient cooling of the fluids to be cooled.

[0005] In current air conditioning system architectures, one encounters either independent exchangers or exchangers grouped together in sets of exchangers.

[0006] The heat exchanger assemblies allow for a reduction in footprint and simplified maintenance, as the heat exchangers are all arranged in a close location.

[0007] However, this proximity of exchangers leads to disadvantages, particularly thermal ones: the close proximity of the exchangers can lead to the formation of thermal bridges, i.e. the transmission of heat from one exchanger to another.

[0008] These thermal bridges must be avoided at all costs because they can cause malfunctions in heat exchange, especially if one heat exchanger is dealing with a fluid at a much higher temperature than the other heat exchanger.

[0009] The document GB 2 015 723 A describes an air conditioning system for an aircraft. Objectives of the invention

[0010] The invention aims to provide an air conditioning system for an aircraft.

[0011] The invention also aims to provide an aircraft air conditioning system in which the heat exchangers have a close location or near environment.

[0012] The invention aims in particular to provide an aircraft air conditioning system avoiding thermal bridges between heat exchangers. Description of the invention

[0013] To achieve this, the invention proposes an air conditioning system for an aircraft according to claim 1.

[0014] An air conditioning system according to the invention thus makes it possible to group at least two heat exchangers together by using dynamic air as a common cold pass for the heat exchangers, while avoiding thermal bridges between the heat exchangers.

[0015] In particular, the arrangement of the exchangers in the longitudinal direction, which is the direction of dynamic air circulation in the channel, allows the heat exchangers to be supplied by a cold pass composed of dynamic air.

[0016] The air passage provides thermal insulation between the different heat exchangers. Since the dynamic airflow occurs along the longitudinal direction, the air circulating in this insulating air passage does not come into contact with the heat exchangers but simply forms the insulating air gap within the space created by the separation between them. Thus, no heat is transferred from one heat exchanger to another, and in particular, no dynamic air that would have been heated by passing through one heat exchanger then circulates through another.

[0017] Dynamic air thus provides a dual function: cooling via the cold pass in each exchanger, and insulation between the heat exchangers.

[0018] Advantageously and according to the invention, at least two heat exchangers among the exchangers in the assembly are manufactured in the same matrix.

[0019] According to this variant, manufacturing the entire set of exchangers in the same die allows for a simplification of the manufacturing process and a reduction in costs.

[0020] Furthermore, it allows the air passage to be created directly during the manufacturing of the heat exchangers. Thus, the air passage is pre-formed between the heat exchangers during manufacturing, and this avoids the need to form it during the installation of the exchangers as a whole, for example in an aircraft air conditioning system.

[0021] The fluid forming the hot pass of each exchanger is air.

[0022] The heat exchangers are therefore of the air / air type and are particularly suitable for cooling and air conditioning in an aircraft air conditioning system.

[0023] Advantageously and according to the invention the distance between the two exchangers, in the transverse direction, is between 1 mm and 10 mm, preferably between 3 mm and 6 mm.

[0024] These distances allow both to guarantee a minimum spacing between the heat exchangers to allow thermal insulation between the two heat exchangers, and to have a space small enough for a limited footprint of all the exchangers in the dynamic air circulation channel.

[0025] The invention also relates to an air conditioning system characterized in that it comprises a set of heat exchangers according to the invention.

[0026] An air conditioning system according to the invention makes it possible to bring together two exchangers in a close location without however causing thermal bridges which would be detrimental to their efficiency.

[0027] According to the invention, a first exchanger of the assembly forms a primary exchanger of the air conditioning system, cooling taken air and transmitting the cooled air to an inlet of a compressor of the air conditioning system, and a second exchanger of the assembly forms a main exchanger of the air conditioning system, cooling the air exiting said compressor.

[0028] According to the invention, the primary heat exchanger and the main heat exchanger can operate without thermal bridging. In particular, the heat released during passage through one of the exchangers is never transferred to the other exchanger by the dynamic air, the operation of the two exchangers being independent.

[0029] Advantageously, and according to the invention, the air conditioning system comprises a turbomachine including a drive shaft, said drive shaft being rotated by the turbomachine and driving a fan configured to supply dynamic air passing through the dynamic air circulation duct. The dynamic air is thus formed from the " RAM air "(in English), which is set in motion by the turbomachine's fan.

[0030] The invention also relates to an aircraft comprising an air conditioning system according to the invention. List of figures

[0031] Other objects, features and advantages of the invention will become apparent from the following description, given by way of non-limiting example only, and which refers to the accompanying figures in which: [ Fig. 1[ ] is a schematic view of a heat exchanger assembly according to an embodiment of the invention. ] Fig. 2 ] is a simplified schematic view of an air conditioning system according to an embodiment of the invention. Detailed description of an embodiment of the invention

[0032] In the figures, the scales and proportions are not strictly respected for the purposes of illustration and clarity.

[0033] In addition, identical, similar or analogous elements are designated by the same references in all figures.

[0034] There figure 1 illustrates a set of 10 heat exchangers according to an embodiment of the invention.

[0035] The heat exchanger comprises at least two adjacent heat exchangers, here a first heat exchanger 12a and a second heat exchanger 12b, arranged in a dynamic air circulation channel 14. The exchangers are advantageously manufactured from the same matrix.

[0036] The dynamic air circulation channel 14 extends along a longitudinal direction, which corresponds to the direction of dynamic air circulation through said channel 14, as schematically represented by arrows 16a to 16f and arrow 18 representing the dynamic air circulation through channel 14.

[0037] The heat exchangers 12a, 12b are thus adjacent along a transverse direction (not shown) perpendicular to the longitudinal direction.

[0038] The dynamic air forms a cold pass in each of the heat exchangers. In schematic form figure 1, a first part of the dynamic air represented by arrows 16a, 16b, 16c forms the cold pass of the first heat exchanger 12a and a second part of the dynamic air represented by arrows 16d, 16e, 16f forms the cold pass of the second heat exchanger 12b.

[0039] This dynamic air forming the cold pass of the heat exchangers 12a, 12b allows the cooling of a fluid forming a hot pass of each exchanger: the first heat exchanger 12a includes a first circuit 20a allowing the circulation of a first fluid forming a hot pass of said first heat exchanger 12a, and the second heat exchanger 12b includes a second circuit 20b allowing the circulation of a second fluid forming a hot pass of said second heat exchanger 12b.

[0040] The spacing between heat exchangers 12a and 12b allows for the formation of an air passage between them, creating, as the dynamic air passes through, a thermally insulating air layer 18 between said exchangers. The arrow representing the dynamic air layer 18 is thicker than arrows 16a to 16f only for clarity, and the thickness of said arrow does not imply any particular characteristic of the dynamic air forming the air layer 18 compared to the dynamic air forming a cold pass of heat exchangers 12a and 12b.

[0041] The presence of the air gap 18 prevents thermal bridging between heat exchangers 12a and 12b, that is, the transfer of heat from one heat exchanger to the other. When the two fluids forming the hot pass of either exchanger have very different temperatures, thermal bridging could cause malfunctions in the exchangers; in particular, the colder fluid could be heated by the dynamic air cooling the hotter fluid. Thus, the thermally insulating air gap 18 ensures the proper functioning of both heat exchangers 12a and 12b.

[0042] The set of 10 heat exchangers is particularly suitable for use in an aircraft air conditioning system, one embodiment of which is shown with reference to the figure 2 .

[0043] The heat exchanger assembly 10 comprises, as before, two heat exchangers 12a and 12b arranged in the dynamic air circulation channel 14. The dynamic air forms a first cold pass 16ac of the first heat exchanger 12a (corresponding to arrows 16a to 16c of the figure 1 ), a second cold pass 16df of the second heat exchanger 12b (corresponding to arrows 16d to 16f of the figure 1 ). The insulating blade 18 crosses the channel 14 between the two heat exchangers 12a, 12b, in the longitudinal direction.

[0044] The first exchanger 12a is a primary heat exchanger, often called PHX for Primary Heat Exchanger In English. The first heat exchanger 12a receives air 22 drawn, for example, from the aircraft engines or from outside the aircraft and then compressed. This drawn air 22 forms the hot pass of the first heat exchanger 12a.

[0045] The air 24 cooled in the first heat exchanger is transmitted to the compressor 26 of a turbomachine 28, where it is compressed. The turbomachine 28 further comprises a turbine 30 and a fan 32, both connected to each other and to the compressor by a drive shaft 34. The turbomachine 28 may also include an electric motor, not shown, to form a powered turbomachine.

[0046] The air 36 compressed by the compressor 26 forms the hot pass of the second heat exchanger 12b. The second heat exchanger 12b thus forms a main heat exchanger, often called MHX for Main Heat Exchanger in English.

[0047] The air 38 cooled by the second heat exchanger 12b is passed to the air conditioning unit 40, which processes this air for conditioning before it is supplied to a cabin 100 of the aircraft. In particular, this processing by the air conditioning unit 40 may include passing through the turbine 30 for expansion and cooling of the air, thereby supplying energy to the turbomachine 28 for its rotation.

[0048] The rotation of the turbomachine's transmission shaft 34, due to energy recovery by the turbine 30, an electric motor, or any other means, drives the operation of the fan 32, which generates the dynamic air that forms both the cold passes 16ac, 16df of the heat exchangers 12a, 12b, and the thermally insulating air blade 18. This dynamic air generated by the air conditioning system is generally called RAM air in English.

Claims

1. Air conditioning system for an aircraft comprising a heat exchanger assembly (10) comprising a ram air flow channel (14) extending in a longitudinal direction, comprising moreover: - at least two separate heat exchangers (12a, 12b) that are adjacent in a transverse direction perpendicular to the longitudinal direction, are arranged in the ram air flow channel (14), and are configured such that the ram air passing through said channel (14) forms a cold pass (16ac, 16df) of each heat exchanger (12a, 12b) by passing through said heat exchanger (12a, 12b) in said longitudinal direction, each heat exchanger (12a, 12b) also being configured for the passage therethrough of a fluid that is intended to be cooled and that forms a hot pass (20a, 20b); and - an air passage which is provided between the heat exchangers and forms a thermally insulating air gap (18) between said exchangers (12a, 12b), and through which the ram air flows, said air passage extending in said longitudinal direction of said ram air flow channel (14), in that a first exchanger (12a) of the assembly forms a primary exchanger of the air conditioning system, cooling the intake air and transmitting the air thus cooled to an inlet of a compressor (26) of the air conditioning system, and in that a second exchanger (12b) of the assembly forms a main exchanger of the air conditioning system, cooling the air leaving said compressor (26).

2. Air conditioning system for an aircraft according to claim 1, characterized in that at least two heat exchangers (12a, 12b) of the exchangers of the assembly are produced in the same mold.

3. Assembly according to any of claims 1 to 2, characterized in that the distance between the two exchangers (12a, 12b), in the transverse direction, is between 1 mm and 10 mm, preferably between 3 mm and 6 mm.

4. Air conditioning system for an aircraft according to any of claims 1 to 3, characterized in that said system comprises a turbine engine (28) comprising a transmission shaft (34), said transmission shaft being rotated by the turbine engine (28) and driving a fan (32) configured to supply the ram air passing through the ram air flow channel (14).

5. Aircraft, characterized in that said aircraft comprises an air conditioning system according to any of claims 1 to 4.