FR3131773A1 - Monobody heat exchanger - Google Patents

Abstract

Heat exchanger (1) comprising at least two helicoid-shaped fluid passages (2), of which at least a portion (3) of the passages are arranged in close proximity to each other, the passages (2) being arranged in a single body (4). FIGURE 5

Description

Single-body heat exchanger

The present invention relates to a heat exchanger comprising at least two fluid passages of which at least a portion of the passages are arranged in close proximity to each other in order to allow thermal exchanges between the two fluids.

Heat exchangers are particularly common devices used in countless applications and devices, especially devices involving heat engines and refrigeration elements. Conventionally, heat exchangers include a long tube in which a fluid circulates. The tubing often forms a circuit in which the tubing alternates back and forth, arranged side by side. When two or more fluids are used, the exchangers are classically serpentine-shaped, with a double winding allowing neighboring tubing to be in thermal contact which can promote heat exchange. These arrangements are generally quite large, with complex architectures and yields that can be improved. To improve these devices, several attempts have been made with arrangements aimed at abandoning the use of long serpentine-shaped tubes.

For example, document US20090101321 describes a heat exchanger comprising a main body into which a plurality of cells aligned next to each other are inserted. This type of device is advantageously compact and efficient, but complex to produce. The rectilinear paths of the cells, however, limit the heat exchange lengths.

Document WO2016074048 describes a heat exchanger consisting of a plurality of superimposed plates in which fluid circulation channels are arranged. This architecture makes it possible to adapt the exchanger according to needs. However, this type of construction with multiple constituent elements is relatively complex and expensive.

These two types of architectures are complex to implement, expensive, with performance levels that can be improved.

To overcome the various drawbacks previously mentioned, the invention provides different technical means.

First of all, a first objective of the invention consists of providing a heat exchanger with improved efficiency.

Another objective of the invention consists of providing a heat exchanger with optimal exchange surface.

Another objective of the invention consists of providing a compact, resistant and durable heat exchanger.

Yet another objective of the invention consists of making a simple connection between the exchanger and the fluid network of the system using this exchanger.

To do this, the invention provides a heat exchanger comprising at least two fluid passages forming a helical-shaped winding, at least a portion of the passages of which are arranged in close proximity to each other, the passages being arranged in a single body and the winding(s) associated with the different fluids having an angular offset in the direction of the winding of at least one degree.

This architecture makes it possible to create a simple, compact, particularly efficient exchanger. The one-piece arrangement of the multiple channels avoids having to use the classic serpentine-shaped windings, which are complex to produce and fragile to use. The exchangers are advantageously produced using additive manufacturing, for example with a 3D printer. This embodiment makes it possible to implement an infinite number of monobloc arrangements, for two, three, four fluids or even more. The heat exchange rates between the different fluids are easily adaptable by modulating parameters such as the lengths of the paths with heat exchanges, the surfaces of the passages, the pitch of the helical spirals, the dimensions of the one-piece body, in particular the length of the body monobloc (in the direction of the longitudinal axis AL described below), the materials of the monobloc body, etc.

According to an advantageous embodiment, the angular offset between the windings is equal to 360 degrees divided by the number of fluid circulating in the exchanger.

The angular offset between the passages of the different fluids makes it possible to provide separate entry and/or exit points for each of the fluids.

For the same fluid, several parallel passages, aligned angularly, are advantageously provided. This makes it possible to increase the exchange surfaces between the fluids.

Advantageously, the passages for each of the fluids are of identical pitch.

The identical pitch of the different passages makes it possible to maintain identical spacing over the entire length of the body, with uniform thermal exchanges. This arrangement also makes it possible to avoid any crossing or intersection between different passages.

Advantageously, the passages allow heat exchanges between at least two separate fluids.

Alternatively, the passages allow heat exchanges between at least three separate fluids.

According to an advantageous embodiment, the single body is elongated along a longitudinal axis AL, the winding being arranged around this axis

According to yet another advantageous embodiment, the exchanger comprises at least one connection chamber, serving as a single entry or exit point for all of the passages of the same fluid.

Such an arrangement facilitates connections between the exchanger and the rest of the fluid circuit.

The connection chambers are advantageously arranged at the end of the single body.

Also advantageously, the single body is metallic, such as copper, steel, or aluminum.

These metals and alloys make it possible to produce highly efficient exchangers.

Advantageously, the heat exchanger comprises a plurality of passages ensuring the path through the exchanger of a first fluid, interposed between a plurality of passages ensuring the path through the exchanger of a second fluid.

This embodiment makes it possible to multiply the heat exchange circuits without requiring an increase in the volume of the exchanger. The monobloc exchanger makes it possible to provide a large number of exchange circuits, which are difficult to achieve using conventional coils.

All the details of production are given in the description which follows, supplemented by Figures 1 to 10, presented solely for the purposes of non-limiting examples, and in which:

Fig.1

there is a schematic representation illustrating an example of a flow path of fluidic passages with two fluids and one passage per fluid, the figure illustrating hollow portions in a solid unitary body not shown in this schematic representation;

Fig.2

there is a schematic representation illustrating an example of a flow path of fluid passages with two fluids and a passage for the first fluid surrounded by two passages for the second fluid;

Fig.3

there is a schematic representation illustrating an example of a flow path of fluid passages with three passages for the first fluid and three passages for the second fluid, arranged alternately;

Fig.4

there is a schematic representation illustrating the example of routing of fluidic passages of the with a representation of connection chambers arranged at the ends of the passages;

Fig.5

there illustrates an example of a single-body exchanger shown in longitudinal section, in which helicoid-shaped passages are arranged;

Fig.6

there illustrates an alternative embodiment of the heat exchanger of the with double winding stage;

Fig.7

there illustrates the interchange of the in top view;

Fig.8

there is a schematic representation illustrating the path of the fluidic passages of the example heat exchanger of the ;

Fig.9

there is a schematic representation of an example of integration of a heat exchanger for an application with a heat engine;

Fig.10

there is a schematic representation of an example of integration of a heat exchanger for an application with a Stirling cycle engine.

DEFINITIONS

By “fluid” we mean a substance (pure or mixture) enabling thermal energy to be transported in a pipe intended for this purpose. A fluid can be in a liquid or gaseous state. Typically, fluids such as water, air, helium, nitrogen, hydrogen, etc. are used.

By “separated fluids” we mean fluids circulating in distant fluidic circuits, without fluidic communication between them. The fluids may be different or the same.

There is a schematic representation of an example of the path of two fluid passages 2 such as these are likely to be arranged in a heat exchanger 1 according to the invention. The unitary body 4 or monobloc (see ) in which these passages are practiced is not illustrated in this figure. We observe each of the fluid passages 2 which forms a helicoid-shaped winding. As illustrated, the winding is carried out around a longitudinal axis AL of the heat exchanger. Also as illustrated, the passages 2 are arranged in close proximity to each other on at least a portion 3 of their helical path, in order to promote thermal exchanges between the fluids of these passages. As illustrated, the different passages are planned with an identical pitch, which makes it possible to plan paths with maximum exchange surfaces. In the examples illustrated the pitch is constant throughout the path, but alternatively, the pitch can be variable along the AL axis.

The unitary or one-piece body 4 in which the passages are arranged allows heat exchanges. For this purpose, a material with high thermal conductivity is provided, preferably metallic, such as aluminum, copper, steel, or other material of this type. In this example, the two windings are angularly offset at the top (input) by 120° and at the bottom (output) by 90°. This offset is evaluated in the direction of the winding from the start of the first winding.

There is a schematic representation of a variant of the example of the , in which a passage 2 for a first fluid (in light in the diagram) is surrounded by two passages 2 provided for a second fluid (in dark in the diagram). As in the example of , each of the fluid passages 2 forms a helical-shaped winding, and the passages are arranged in close proximity to each other on at least one portion 3 of their helical path. In this example, the arrangement favors thermal exchanges between the first fluid (in light) and the second fluid (in dark). In this example, the dark windings are angularly offset from the light winding at the top (input) by 120° and 70° and at the bottom (output) by 20° and 90°.

There is a schematic representation of another variation of the example of the , in which three passages 2 provided for a first fluid (in light on the diagram) are arranged alternating with three passages 2 provided for a second fluid (in dark on the diagram). As in the example of , each of the fluid passages 2 forms a helical-shaped winding, and all the passages 2 are arranged in close proximity to each other on at least one portion 3 of their helical path. In this example, the arrangement favors thermal exchanges between the first fluid (in light) and the second fluid (in dark). The angular offset between the three passages 2 devoted to the first fluid (clearly on the ) and the three passages 2 devoted to the second fluid (in dark on the ) is here 180°. We therefore observe that the passages 2 provided for one and the same fluid are angularly aligned and have angularly identical starting and stopping points. To achieve this type of configuration with multiple windings, the windings provided for the same fluid are arranged parallel to each other, with helicoids increasingly tight from the outer winding towards the inner windings. The pitch is identical for all windings.

There allows us to understand the considerable advantage of these angular alignments for the passages of the same fluid. Indeed, as illustrated in , connection chambers 5 are advantageously arranged opposite each of the starting and stopping points of the passages 2 of the same fluid. A connection chamber 5 makes it possible to provide a single connection for the inlet and a single connection for the outlet of the same fluid. The helicoid-shaped passages 2 are connected to the connection chambers by connecting passages 6. As illustrated, the connecting passages 6 are advantageously arranged parallel to the longitudinal axis AL of the heat exchanger 1. Each connecting passage makes it possible to connect a connection chamber 5 to one or more passages 2 intended for the same fluid. This avoids having to provide multiple connection points for each passage 2 of the same fluid.

Figures 5, 6 and 7 show examples of implementation of connection chambers 5 for examples of heat exchangers 1. The illustrates particularly well the single inputs and outputs easily connectable to the circuits using the fluids of the heat exchanger 1. The connection chambers 5 make it possible to obtain a junction between the fluidic channels and a simple collector located spatially at the same location.

There illustrates an example of a single-body heat exchanger 1 shown in longitudinal section. A one-piece body 4 has the passages 2 in the shape of a helicoid. In this example, the one-piece body 4 is of elongated shape, extending along a longitudinal axis AL, around which the passages 2 are wound in the form of helicoids. The example of realization of the uses a configuration such as that illustrated for the example of Figures 3 and 4. To manufacture such a heat exchanger, a process with addition of material is advantageously used, such as for example a 3D printer. This makes it possible to easily implement practically any arrangement with multiple helicoid-shaped passages, with connection chambers at the end of the passages.

Figures 6 and 8 together illustrate an alternative embodiment with several stages of winding the same fluid, i.e. two stages in this example. There , schematically illustrating the path of the fluidic passages in the form of helicoids, makes it possible to clearly visualize the successive stages of connection with a connection chamber 5 via connecting passages 6 of different lengths, in this example two short passages and two longer passages allowing a new connection to be made at the same angular position, below the first winding turn. To carry out this implementation, the pitch of each of the turns is increased in order to free up the space required to position the second winding stage.

As mentioned previously, this type of exchanger is advantageously manufactured by additive manufacturing, in particular by 3D printing.

APPLICATION EXAMPLES

There illustrates an example of application of a heat exchanger 1 as previously described. In this example, the heat exchanger 1 is connected to a heat engine 7, such as for example a vehicle engine, to allow its cooling in conjunction with an air flow. Exchanger 1 is thus used as a counter-current exchanger. The coolant circulates in a closed circuit and allows the extraction of the thermal energy emitted by combustion. The hot cooling fluid coming from the engine enters an exchanger connector at the hot fluid inlet 8. After heat exchange, the cooled cooling fluid leaves the exchanger via the fluid outlet 9 and returns to the heat engine 7 for a new heat absorption cycle.

The air is used in a forced or non-forced open circuit and makes it possible to recover the heat supplied to the exchanger by the hot cooling fluid.

The fresh air inlet 10 is connected to a connection chamber of the exchanger. After heat exchange, the heated air leaves the exchanger via hot air outlet 11. This hot air is released into the ambient environment.

This architecture has the advantage of compactness and weight savings compared to conventional radiators, for comparable or even greater efficiency.

There illustrates another example of application of a heat exchanger 1, this time for use as a regenerator for a Stirling cycle engine. Such an engine is described in application FR2009877. Such an engine can be with four double-acting pistons or a multiple of four double-acting pistons. There shows only the two opposing gas volumes, one of which is in the heating phase (represented by waves, on the right side of the figure), and the other in the cooling phase (represented by hatching, on the left side of the figure). the figure). The volume of gas in the cooling phase passes through the heat exchanger 1, transfers its thermal energy to the gas in the heating phase, and allows maximum energy to be recycled, thus increasing the efficiency of the system. The figure schematically shows the working volume X in hot zone 12, the working volume

This architecture has several advantages including an improvement in performance. The helical architecture allows an exchange between opposing fluids without crossing with other volumes and with perfect symmetry for all the fluidic paths of the working gases of the Stirling engine in relation to the winding axis. This makes it possible to obtain a perfect operating balance due to the volume equivalence between each of the working gases.

Claims (9)

Heat exchanger (1) comprising at least two fluid passages (2) forming a helical-shaped winding, of which at least one portion (3) of the passages are arranged in immediate proximity to each other, characterized in that the passages (2) are arranged in a single body (4) and in that the winding(s) associated with the different fluids have an angular offset in the direction of the winding of at least one degree. Heat exchanger according to claim 1, in which the angular offset between the windings is equal to 360 degrees divided by the number of fluid circulating in the exchanger. Heat exchanger according to any one of claims 1 or 2, in which the passages (2) for each of the fluids are of identical pitch. Heat exchanger according to any one of claims 1 to 3, in which the passages allow heat exchanges between at least two separate fluids. Heat exchanger according to any one of claims 1 to 4, in which the single body (4) is elongated along a longitudinal axis AL, the winding being arranged around this axis. Heat exchanger according to any one of claims 1 to 5, comprising at least one connection chamber (5), serving as a single entry or exit point for all of the passages (2) of the same fluid. Heat exchanger according to claim 6, in which the connection chambers (5) are arranged at the end of the single body (4). Heat exchanger according to any one of the preceding claims, in which the single body (4) is metallic. Heat exchanger according to claim 8, in which the body is made of copper, or steel, or aluminum.