FR2891615A1 - HEAT EXCHANGER WITH ALTERNATE FLAT TUBES. - Google Patents

Abstract

The heat exchanger, comprising a series of alternating flat tube panels (11, 12) for circulating first and second fluids, linked to collector spaces formed by cavities (25) in manifold blocks that are offset relative to one another so the remain separate. The cavities are linked by connectors (34, 35, 36, 37) at opposite ends of the tube panels to feed and return pipes.

Description

RFR0245

  The invention relates to a heat exchanger for exchanging heat between a first fluid and a second fluid, comprising a bundle of flat tubes formed by the alternating stack of first tubes for the circulation of the first fluid. fluid and second tubes for the circulation of the second fluid, all the tubes of the beam opening into fluid collection spaces at least on a first face of the beam.

  The object of the invention is to provide the fluid collecting spaces 15 simply and economically with a small footprint.

  The invention aims in particular at a heat exchanger of the type defined in the introduction, and provides that said collection spaces are formed by recesses formed in a first collector block and at least one of which is associated with each tube, the ends of the second tubes and the corresponding recesses being offset in the longitudinal direction of the tubes, relative to the ends of the first tubes and the corresponding recesses, so that the recess or recesses associated with a first tube are limited in the stacking direction by faces of the first block and that the recess or recesses associated with a second tube are limited in the stacking direction by the faces of the two first adjacent tubes.

  Optional features of the invention, complementary or substitution, are set out below: - Each first tube and / or each second tube is associated with a single recess for circulation in a single pass in each of these tubes.

  - All the tubes of the beam open, on a second face of the beam opposite the first, in fluid collecting spaces formed by recesses formed in a second collector block and at least one of which is associated with each tube, the recesses located opposite the second face of the beam and the corresponding ends of the tubes being also offset in the longitudinal direction of the tubes so that the or each of these recesses is limited in the stacking direction by the faces of the two plates adjacent or adjacent tubes.

  - The offset on the second side of the beam is such that each recess associated with a first tube is limited by the faces of two second tubes and each recess associated with a second tube is limited by the faces of the second block.

  The first tubes and the second tubes are of substantially the same length.

  - The second block is formed of one or more components separate from the component or components forming the first block.

  - Said first collector block consists of mutually stacked plates, each of which is associated with a tube, the faces of each plate of the first collector block being located substantially in the same plane as the faces of the associated tube.

  Said second collector block consists of mutually stacked plates each of which is associated with a tube, the faces of each plate of the second collector block being located substantially in the same plane as the faces of the associated tube.

  - An orifice of a plate opens into an edge thereof which is applied along a longitudinal edge of the associated tube.

  The invention also relates to a fluid circuit containing a heat exchanger as defined above as an internal exchanger, the first fluid and the second fluid being constituted by the fluid circulating in the circuit, in two locations of this one where it presents different temperatures.

  In particular, the circuit according to the invention may be an air conditioning loop in which circulates a refrigerant fluid working at high pressures such as CO2, the first fluid and the second fluid being constituted by the high-pressure refrigerant fluid and the other by the refrigerant fluid at low pressure.

  The features and advantages of the invention are set forth in more detail in the description below, with reference to the accompanying drawings.

  Figure 1 is a diagram of a vehicle air conditioning loop containing an internal heat exchanger according to the invention.

  Figure 2 is a perspective view of a heat exchanger according to the invention.

  Figure 3 is a corresponding exploded perspective view.

  FIG. 4 is a partial view of the heat exchanger illustrated in FIGS. 2 and 3, in section along the line IV - IV of FIG. 5.

  FIGS. 5 and 6 are sectional views of this heat exchanger, respectively along lines V-V and VI-VI of FIG. 4.

  The air conditioning loop shown in Figure 1 is known in itself in its general design. It comprises a compressor 1 which brings to a high pressure a cooling fluid consisting of CO2, followed by a gas cooler 2 which makes it possible to transfer to a stream of air, not represented, a portion of the heat stored by the refrigerant during its compression by the compressor 1. Downstream of the gas cooler 2 is disposed a 3H path of an internal heat exchanger 3 for further cooling of the fluid. The track 3H is followed by a pressure reducer 4, then an evaporator 5 which is swept by an unrepresented air flow intended to be sent into the passenger compartment of the vehicle. At the outlet of the evaporator, the fluid passes into a reservoir 6. The fluid in the relaxed gas state leaving the reservoir 6 passes into the second path 3B of the internal heat exchanger 3, against the flow of the circulation in lane 3H, to be heated by the high pressure gas flowing in the latter, before returning to the compressor 4.

  According to the invention, the internal exchanger 3 has the structure illustrated in FIGS. 2 to 6. It comprises an alternating stack of first flat tubes 11 and second flat tubes 12. In the illustrated example, the exchanger comprises first three tubes 11 and three second tubes 12, each tube having a multiplicity of parallel channels 13, 14 for the circulation of fluid, extending parallel to the longitudinal direction, here vertical, of the tube and opening at both ends thereof . Each tube 11 is associated with an upper plate 15 and a lower plate 17 and each tube 12 is associated with an upper plate 16 and a lower plate 18. The plates 15 and 17 associated with a tube 11 have main faces located in the same planes that the two main faces of this tube, and therefore have the same thickness as this one. Similarly, the plates 16 and 18 associated with a tube 12 have major faces located in the same planes as the two main faces of this tube, and therefore have the same thickness as this one. In the example shown, this thickness is the same for the tubes 11 and for the tubes 12.

  Each of the plates 15-18 comprises a main part 20 extending facing the end of the tube over the entire width thereof, and two lateral flanges 21, 22 coming into sealing contact, after soldering, respectively with the two opposite longitudinal edges 23 and 24 of the tube, near its end. Between the main portion 20 of each plate and the corresponding tube end is a fluid collecting space 25 into which all channels 13 or 14 of the tube open.

  As can be seen more particularly in FIG. 2, the assembly formed by a first tube 11 and its associated plates 15 and 17 and the assembly consisting of a second tube 12 and its associated plates 16 and 18 have the same outline, and these sets are mutually stacked to produce a cylindrical block. On the other hand, although the tubes 11 and 12 have the same length, their upper and lower ends are not located in the same planes.

  As can be seen in FIG. 4, the lower ends of the first tubes 11 and those of the second tubes 12 are located in respective horizontal planes P1 and P2, the plane Pl being shifted upwards by a distance D with respect to the plane P2. The length of the tubes being the same as indicated above, the upper ends of the tubes 11 and those of the tubes 12 are located in respective horizontal planes mutually offset by the distance D. The fluid collecting spaces 25, adjacent to the ends of the tubes also have a mutual vertical offset, this offset being such that: - the recess of an upper plate 15 associated with a first tube 11 is delimited in the stacking direction by the two upper plates 16 adjacent, associated with second respective tubes 12; - The recess of a lower plate 17 associated with a first tube 11 is defined in the stacking direction by the flat faces of the two second tubes 12 adjacent; the recess of an upper plate 16 associated with a second tube 12 is delimited in the stacking direction by the plane faces of the two first adjacent tubes 11; - The recess of a lower plate 18 associated with a second tube 12 is defined in the stacking direction by the two adjacent lower plates 17 associated with respective first tubes 11.

  The above applies to the recesses associated with the four intermediate tubes of the stack. With regard to the two end tubes, that is to say the tube 11 on the right and the tube 12 on the left in FIG. 4, each recess is delimited, towards the inside of the bundle formed by the stacking tubes 11 and 12 and plates 15 to 18, by one of these tubes or one of these plates as indicated above, and towards the outside of the beam by a solid outer plate which will be described later, having the same outer contour as the plates 15 to 18 but without recess.

  A notch 30 is formed in the rim 22, located on the right of Figure 5, of each upper plate 15, so as to be adjacent to the side edge 24 of the corresponding tube 11. The notch 30 thus forms an orifice passing through the plate 15, surrounded by the rim 22 and the edge 24, and separated from the recess 25. The orifices 30 of the different plates are mutually aligned and each communicates with the recesses 25 of the plates 16. adjacent, so that the recesses 25 and the orifices 30 of all the plates 15 and 16 of the heat exchanger are interconnected to form an inlet manifold for the refrigerant fluid at low pressure.

  In each lower plate 17 is drilled a through hole 32 separated from the recess 25 of the same plate. The holes 32 of the different plates are mutually aligned and each communicates with the recesses 25 of the two adjacent plates 18, the recesses and the holes 32 of the set of plates 18 thereby forming an outlet manifold for the low pressure fluid. The low pressure fluid flows in parallel, from top to bottom, in all the channels 14 of the tubes 12, between the inlet chamber and the outlet chamber.

  The upper plate 16-tube 12-lower plate assembly 18 shown in FIG. 6 is identical to the lower plate 17-tube 11 upper plate assembly 15 of FIG. 5, and is derived therefrom by a rotation of a turn around the central longitudinal axis of the beam and by a translation along this axis of the thickness of a tube. As a result, notches 31 in the left flange 21 of the plates 18 cooperate with the recesses 25 of the plates 17 to form an inlet chamber for the high pressure fluid, and holes 33 passing through the plates 16 cooperate with the recesses 25. plates 15 for forming an outlet chamber for the high pressure fluid, the high pressure fluid flowing in parallel in all the channels 13 of the tubes 11, from bottom to top, that is to say against the current relative to the low pressure fluid, between the inlet chamber and the outlet chamber.

  The inlet and the outlet of the fluids of the exchanger are made by pipes carried by the outer plates located at one end of the beam. The upper outer plate 26 located at this end, aligned with the upper plates 15 and 16, is crossed by two not shown openings respectively aligned with the openings 30 and the openings 33 and respectively communicating with an inlet pipe 34 for the fluid to low pressure and with an outlet pipe 37 for the high pressure fluid. Similarly, the lower outer plate 28, aligned with the plates 17 and 18, located at the same end of the bundle as the plate 26 has unshown through openings aligned with the openings 31 and 32 and communicating respectively with an inlet manifold. 35 for the high pressure fluid and with an outlet pipe 36 for the low pressure fluid. The upper and lower outer plates 27, 29 at the opposite end of the bundle are devoid of openings and nozzles.

  In the illustrated example, the dimension of each recess 25 in the longitudinal direction of the tubes is not uniform, but varies gradually in the direction of the width of the tubes. This dimension is maximum at the point where the recess communicates with the openings of the adjacent plates, in the vicinity of one of the lateral edges of the tube, and gradually decreases to the right of the opposite edge of the tube, to take account of the decrease in fluid flow. This variation is advantageous but not necessary.

  Other modifications may be made to the embodiment described and shown without departing from the invention, some of which are discussed below.

  Both fluids can flow in the same direction and not in counterflow.

  At least one of the two fluids can flow in the exchanger in two passes or more. For example, this fluid can flow in one direction in one part of the channels of each tube, and in the opposite direction in the other channels.

  The plate associated with the end of the tube through which the fluid enters and exits then has two separate recesses, cooperating with respective orifices formed in the adjacent plates to contribute to the formation of the inlet and outlet chambers. The channels of the tube can then communicate with each other, at the opposite end thereof, by a recess formed in a plate similar to the plates 15 to 18 but not communicating with any opening of neighboring plates, or by any other known means. A circulation in two passes or more can also be obtained by removing, in at least one plate, the orifice 30 or 31 or 32 or 33, thus separating one of the inlet and outlet chambers described above in one or several chambers aligned in the stacking direction of the beam. Depending on the arrangement of the inlet and outlet chambers for the two fluids, it may be advantageous or necessary to distribute the inlet and outlet pipes between the two ends of the bundle. Such a distribution is also possible with the arrangement of the described chambers.

  The two plates 15 and 17, or 16 and 18, associated with the same tube can be replaced by a single plate by extending and joining on the one hand the two flanges 21, on the other hand the two flanges 22, to form a frame completely surrounding the periphery of the tube. This results in a reduction in the number of parts to manufacture, store and handle during the assembly of the exchanger.

  Finally, the plate stacks 15-16 and 17-18 can be replaced by solid blocks in which the recesses 25 and the openings 30-33 are machined, or by other structures.

Claims (12)

claims   A heat exchanger (3) for exchanging heat between a first fluid and a second fluid, comprising a bundle of flat tubes formed by alternately stacking first tubes (11) for the circulation of the first fluid and second tubes (12) for the circulation of the second fluid, all the tubes of the bundle opening into fluid collection spaces at least on a first face of the bundle, characterized in that said collection spaces are formed by recesses (25) arranged in a first collector block (15, 16) and at least one of which is associated with each tube, the ends of the second tubes and the corresponding recesses being offset in the longitudinal direction of the tubes, relative to the ends of the first tubes and to the corresponding recesses, such that the recess or recesses associated with a first tube are limited in the stacking direction by faces of the first block and the recess or recesses associated with a second tube are limited in the stacking direction by the faces of the two first adjacent tubes.   2. Heat exchanger according to claim 1, wherein at each first tube and / or each second tube is associated a single recess for a single pass in each of these tubes.   3. Heat exchanger according to one of claims 1 and 2, wherein all the tubes of the beam open on a second face of the beam opposite the first in fluid collection spaces formed by recesses (25) formed in a second collector block (17, 18) and at least one of which is associated with each tube, the recesses situated facing the second face of the bundle and the corresponding ends of the tubes being also offset in the longitudinal direction of the tubes of such that the or each of these recesses is limited in the stacking direction by the faces of the two adjacent plates or the two adjacent tubes.   4. Heat exchanger according to the preceding claim, wherein the offset on the second side of the beam is such that each recess (25) associated with a first tube (11) is limited by the faces of two second tubes (12) and that each recess (25) associated with a second tube (12) is bounded by faces of the second block (17).   5. Heat exchanger according to the preceding claim, wherein the first tubes and the second tubes have substantially the same length.   6. Heat exchanger according to one of claims 1 to 5, wherein the second block (17, 18) is formed of one or more components separate from the component or components forming the first block (15, 16).   7. Heat exchanger according to one of the preceding claims, wherein said first collector block consists of mutually stacked plates (15, 16) each of which is associated with a tube (11, 12), the faces of each plate of the first collector block being located substantially in the same plane as the faces of the associated tube.   8. Heat exchanger according to one of the preceding claims, wherein said second collector block consists of mutually stacked plates (17, 18) each of which is associated with a tube (11, 12), the faces of each plate of the second collector block being located substantially in the same plane as the faces of the associated tube.   9. Heat exchanger according to one of claims 7 or 8, wherein a plurality of recesses (25) for one of the first and second fluids, formed in different plates (15, 16) of the same block, communicate with each other. through orifices (33) of the intermediate plates (16, 15) of this block 2891615 12 to form a chamber for said first or second fluid, separated from the recesses (25) for the other fluid.   10. Heat exchanger according to the preceding claim, wherein an orifice (30) of a plate (15) opens into an edge thereof which is applied along a longitudinal edge (24) of the associated tube ( 11).   11. A fluid circuit containing a heat exchanger (3) according to one of the preceding claims as an internal exchanger, the first fluid and the second fluid being constituted by the fluid flowing in the circuit, in two places (3H, 3B) thereof where it has different temperatures.   12. An air conditioning loop according to claim 11, wherein circulates a refrigerant working at high pressures such as CO2, the first fluid and the second fluid being constituted by the high-pressure refrigerant and the other by the refrigerant fluid at low pressure.