Heat exchanger comprising a stack of cells

Abstract

A heat exchanger suitable to be used as a recuperator in a micro gas turbine including a stack of cells. Each of the cells includes a pair of mutually spaced-apart plates and layers including heat exchange elements arranged at the outer surfaces of the plates and between the plates. Each of the layers including heat exchange elements can include at least one discrete spatial component incorporating a number of elements. Both a supply header and a discharge header of the heat exchanger can be made of only two components at the position of the stack of cells. Compensating for heat expansion effects can be via a bellows-shaped pipe portion of a supply conduit.

Claims

1. A heat exchanger comprising: a stack of cells, each cell comprising: a pair of mutually spaced-apart plates configured and arranged to define: an internal fluid flow path of the cell; and an external fluid flow path of the cell; heat exchange elements arranged in each of the fluid flow paths; and a supply conduit; wherein the mutually spaced-apart plates are connected to each other along the periphery thereof, except at positions where an inlet to and an outlet from the internal fluid flow path of the cell are located; and wherein the supply conduit: extends a length from the inlet to the internal fluid flow path of the cell; has a substantially straight longitudinal axis along the length; and has a flexible portion that is compressible and expandable in a direction along the substantially straight longitudinal axis in which the supply conduit extends; a housing enclosing the stack of cells; and a supply header having a substantially straight longitudinal axis extending generally perpendicular to the substantially straight longitudinal axis of the supply conduit of the respective cells, the supply header configured for supplying fluid to the internal fluid flow path of the respective cells; wherein the inlet to the internal fluid flow path of the respective cells is connected to the supply header through the supply conduit of the respective cells.

2. The heat exchanger according to claim 1, wherein for each cell: the supply conduit has a substantially straight longitudinal axis along the entire length of the supply conduit; and the flexible portion of the supply conduit includes a bellows-shaped pipe portion.

3. The heat exchanger according to claim 1, wherein for each cell, the supply conduit comprises a nozzle pipe portion that diverges in the direction of the inlet to the internal fluid flow path.

4. The heat exchanger according to claim 1, wherein for each cell, the heat exchange elements of at least one of the fluid flow paths is defined by at least one discrete spatial component incorporating at least a portion of the heat exchange elements and is at least connected to an adjacent one of the mutually spaced-apart plates.

5. The heat exchanger according to claim 1, wherein for each cell, the heat exchange elements of the internal fluid flow path is defined by at least one discrete spatial component incorporating at least a portion of the heat exchange elements and is connected to both mutually spaced-apart plates.

6. The heat exchanger according to claim 4, wherein at least one discrete spatial component is selected from the group consisting of a wire wound to a coil, a wire mesh, a foil, a louvre, an elongated rib, and a metal foam.

7. The heat exchanger according to claim 4, wherein the heat exchange elements of at least one of the fluid flow paths is defined by a plurality of discrete spatial components that includes a wire wound to a coil; and wherein the spatial components extend alongside each other in a substantially parallel arrangement.

8. The heat exchanger according to claim 1 further comprising a discharge header having a substantially straight longitudinal axis extending generally perpendicular to the substantially straight longitudinal axis of the supply conduit of the respective cells, the discharge header configured for discharging fluid from the internal fluid flow path of the respective cells; wherein the discharge header comprises a connection plate provided with slotted discharge openings; wherein the connection plate is arranged against the cells; and wherein each of the slotted discharge openings is aligned with the outlet of the internal fluid flow path of the respective cells.

9. The heat exchanger according to claim 1 further comprising a discharge header for discharging fluid from the internal fluid flow path of the respective cells; wherein the discharge header comprises a connection plate provided with slotted discharge openings; wherein the connection plate is arranged against the cells; wherein each of the slotted discharge openings is aligned with the outlet of the internal fluid flow path of the respective cells; wherein the discharge header is composed of only the connection plate and a closure component at the position of the stack of cells; and wherein the connection plate and the closure component jointly form a pipe-like entirety.

10. The heat exchanger according to claim 1, wherein the supply header comprises a connection plate having supply openings; and wherein the supply conduit of the respective cells is connected to the connection plate at the position of a respective supply opening of the supply openings.

11. The heat exchanger according to claim 10, wherein the supply header is composed of only the connection plate and a closure component at the position of the stack of cells; and wherein the connection plate and the closure component jointly form a pipe-like entirety.

12. The heat exchanger according to claim 1 further comprising a holder component for supporting the cells on the supply header.

13. The heat exchanger according to claim 12, wherein the holder component is shaped like a rack or a plurality of adjacent racks; and wherein the holder component is configured to receive and hold a portion of the respective cells.

14. A micro gas turbine comprising: a compressor; a turbine; a combustor; and a heat exchanger according to claim 1; wherein the compressor is configured to take in and pressurize gas; wherein the combustor is configured to take in pressurized gas from the compressor and to generate hot gas on the basis of fuel combustion; wherein the turbine is configured to take in and expand hot gas generated by the combustor; and wherein the heat exchanger is configured and arranged to pre-heat pressurized gas before being supplied to the combustor by allowing the pressurized gas to exchange heat with expanded gas obtained from the turbine.

15. The micro gas turbine according to claim 14, wherein the internal fluid flow path of each of the cells of the heat exchanger is in communication with the compressor for taking in pressurized gas from the compressor; and wherein the external fluid flow path of each of the cells of the heat exchanger is in communication with the turbine for taking in expanded gas from the turbine.

16. The heat exchanger according to claim 1, wherein for each cell: the internal fluid flow path of the cell is configured between two inner surfaces of the mutually spaced-apart plates facing each other; and the external fluid flow path of the cell is configured at two outer surfaces of the mutually spaced-apart plates facing away from each other.

17. The heat exchanger according to claim 10, wherein the supply openings are arranged in the connection plate in two columns extending alongside each other; and wherein supply openings in one of the columns are at an intermediate position relative to supply openings in the other of the columns.

18. A heat exchanger comprising: a stack of cells; and a housing enclosing the stack of cells; wherein each cell comprises: a pair of mutually spaced-apart plates; heat exchange elements; and a supply conduit; wherein the pair of mutually spaced-apart plates of each cell are configured and arranged to define an internal fluid flow path of the cell and an external fluid flow path of the cell; wherein the mutually spaced-apart plates of each cell are connected to each other along the periphery thereof, except at positions where an inlet to and an outlet from the internal fluid flow path are located; wherein the heat exchange elements of each cell are arranged in each of the fluid flow paths of the cell; wherein the supply conduit of each cell extends a length from the inlet to the internal fluid flow path, the supply conduit having a substantially straight longitudinal axis along the length; wherein the supply conduit of each cell has a flexible portion that is compressible and expandable in a direction along the substantially straight longitudinal axis in which the supply conduit extends; and wherein the heat exchanger further comprises one or both of: a discharge header having a substantially straight longitudinal axis extending generally perpendicular to the longitudinal axis of the supply conduit, the discharge header configured for discharging fluid from the internal fluid flow path of the respective cells, wherein the discharge header comprises a connection plate provided with slotted discharge openings, wherein the connection plate is arranged against the cells, and wherein each of the slotted discharge openings is aligned with an outlet of an internal fluid flow path of a cell; and a supply header having a substantially straight longitudinal axis extending generally perpendicular to the longitudinal axis of the supply conduit, the supply header configured for supplying fluid to the internal fluid flow path of the respective cells, wherein the inlet to the internal fluid flow path of the respective cells is connected to the supply header through the supply conduit of the cells.

19. The heat exchanger according to claim 18, wherein one or more of: the supply header comprises a connection plate having supply openings, wherein the supply conduit of the respective cells is connected to the connection plate at the position of a respective supply opening of the supply openings; the supply header is composed of only a connection plate having supply openings and a closure component at the position of the stack of cells, wherein the supply conduit of the respective cells is connected to the connection plate at the position of a respective supply opening of the supply openings, and wherein the connection plate and the closure component jointly form a pipe-like entirety; the heat exchanger further comprises a holder component for supporting the cells on the supply header; for each cell, the internal fluid flow path of the cell is configured between two inner surfaces of the mutually spaced-apart plates facing each other, wherein the external fluid flow path of the cell is configured at two outer surfaces of the mutually spaced-apart plates facing away from each other; for each cell, the supply conduit has a substantially straight longitudinal axis along the entire length of the supply conduit, wherein the flexible portion of the supply conduit includes a bellows-shaped pipe portion; for each cell, the supply conduit comprises a nozzle pipe portion that diverges in the direction of the inlet to the internal fluid flow path; for each cell, the heat exchange elements of at least one of the fluid flow paths is defined by at least one discrete spatial component incorporating at least a portion of the heat exchange elements and is at least connected to an adjacent one of the mutually spaced-apart plates; for each cell, the heat exchange elements of the internal fluid flow path is defined by at least one discrete spatial component incorporating at least a portion of the heat exchange elements and is connected to both mutually spaced-apart plates; the discharge header has a substantially straight longitudinal axis extending generally perpendicular to the longitudinal axis of the supply conduit of the respective cells; and the discharge header is composed of only the connection plate and a closure component at the position of the stack of cells, wherein the connection plate and the closure component jointly form a pipe-like entirety.

20. The heat exchanger according to claim 19, wherein one or more of: the supply openings are arranged in the connection plate in two columns extending alongside each other, wherein supply openings in the one column are at an intermediate position relative to supply openings in the other column; the holder component is shaped like a rack or a plurality of adjacent racks, wherein the holder component is configured to receive and hold a portion of the respective cells; the at least one discrete spatial component is selected from the group consisting of a wire wound to a coil, a wire mesh, a foil, a louvre, an elongated rib, and a metal foam; and the heat exchange elements of at least one of the fluid flow paths is defined by a plurality of discrete spatial components that includes a wire wound to a coil, wherein the spatial components extend alongside each other in a substantially parallel arrangement.

Description

(1) The invention will be further elucidated on the basis of the following description of an example of a recuperator and various components thereof.

(2) Reference will be made to the drawing, in which equal reference numerals indicate equal or similar components, and in which:

(3) FIG. 1 diagrammatically shows a perspective view of a recuperator according to the invention;

(4) FIG. 2 diagrammatically shows a first perspective view of a stack of cells, a supply header and a discharge header as present in the recuperator;

(5) FIG. 3 diagrammatically shows a second perspective view of a stack of cells, a supply header and a discharge header as present in the recuperator, with a component of the supply header removed so that a connection plate of the supply header can be seen;

(6) FIG. 4 diagrammatically shows a perspective view of a single cell from the stack of cells of the recuperator;

(7) FIG. 5 diagrammatically shows a sectional view of a portion of a cell;

(8) FIG. 6 diagrammatically shows a planar view of a portion of an arrangement of wire coils as present in the cell;

(9) FIG. 7 diagrammatically shows a perspective view of a connection plate which is part of the supply header;

(10) FIG. 8 diagrammatically shows a perspective view of a connection plate which is part of the discharge header; and

(11) FIG. 9 illustrates application of the recuperator in a micro gas turbine.

(12) The figures relate to a recuperator 101 having features according to the invention, as will now be explained. The recuperator 101 as shown and described represents only one example of many possibilities existing within the framework of the invention.

(13) In the shown example, the recuperator 101 is intended to be used as a gas-to-gas heat exchanger and is particularly suitable for application in the context of a micro gas turbine, which does not alter the fact that application of the recuperator 101 in other contexts is feasible as well.

(14) FIG. 1 provides a view of the exterior of the recuperator 101, showing a housing 10 of the recuperator 101 that serves as an outer shell enclosing various components of the recuperator 101. FIG. 2 shows interior components of the recuperator 101, particularly an assembly of a stack 11 of cells 20, a supply header 30 and a discharge header 40. The stack 11 of cells 20 and the discharge header 40 are also shown in FIG. 3, wherein further the supply header 30 is partially shown as well. FIG. 4 shows a single cell 20 from the stack 11 of cells 20 of the recuperator 101.

(15) Each of the cells 20 used in the shown recuperator 101 comprises a pair 21 of mutually spaced-apart plates 22, 23 having a substantially rectangular periphery and being generally planar, i.e. free from curves. This particular design of the plates 22, 23 is not essential within the framework of the invention, and the present disclosure of various special features of the invention is not limited to this particular design. The plates 22, 23 are connected to each other along the periphery thereof so as to delimit an internal space, except at positions where an inlet 24 to and an outlet 25 from the internal space are located. In particular, the plates 22, 23 may be provided with edges of a special design which can be welded and/or brazed together during the manufacturing process of the cell 20, without a need for using an additional frame or the like. Preferably, the connection is made along a line that is practically in the middle of the two plates 22, 23, so that it is ensured that local thermal stresses during the welding process will not cause deformation of the cell 20, particularly one of the plates 22, 23. During operation of the recuperator 101, the internal space of the cells 20 serves as an internal fluid flow path. Further, a plurality of heat exchange elements 50 is arranged in the internal fluid flow path, and also on the two outer surfaces 22a, 23a of the plates 22, 23 facing away from each other, i.e. in an external fluid flow path of the cell 20.

(16) As can be seen in FIG. 5, the cell 20 has a layered structure, comprising successively a first outer layer 1 of heat exchange elements 50, a first plate 22, an intermediate layer 2 of heat exchange elements 50, a second plate 23, and a second outer layer 3 of heat exchange elements 50. In respect of the intermediate layer 2 of heat exchange elements 50, it is noted that this layer 2 may comprise heat exchange elements 50 which are connected to both plates 22, 23, but it is also possible for this layer to comprise heat exchange elements 50 which are connected to only one of the plates 22, 23, wherein it may be so that a number of heat exchange elements 50 is connected to the first plate 22 and that the rest of the heat exchange elements 50 is connected to the second plate 23. However, in view of having optimal mechanical strength of the cell 20, the first option is preferred, as in that case, the plates 22, 23 are not only connected to each other along the periphery thereof, but also through the plurality of heat exchange elements 50. Thus, the cell 20 can be very well made suitable for applications involving relatively high pressures.

(17) According to an advantageous option, the heat exchange elements 50 are not provided as individual components, but are arranged on the respective plates 22, 23 as part of a discrete spatial component comprising a plurality of heat exchange elements 50. In the example as shown in the figures, each layer 1, 2, 3 of heat exchange elements 50 comprises a number of discrete spatial components 51 in the form of elongated wire coils. As illustrated in FIG. 6, the wire coils 51 of each layer 1, 2, 3 are arranged so as to extend substantially parallel to each other.

(18) The cell 20 according to the shown example is made by providing the two plates 22, 23 and a plurality of wire coils 51, and making a stack 12 of a first number of wire coils 51 in the substantially parallel arrangement as mentioned, the first plate 22, a second number of wire coils 51 in the substantially parallel arrangement as mentioned, the second plate 23, and a third number of wire coils 51 in the substantially parallel arrangement as mentioned. The stack 12 may be prepared for vacuum brazing, i.e. provided with a suitable filler agent at appropriate places before putting the stack 12 together and exerting pressure on the stack 12 once it has been put together, and heated in an oven so that the various layers 1, 2, 3 of heat exchange elements 50 and the plates 22, 23 get interconnected. Interconnecting the plates 22, 23 along the periphery thereof is then performed after the vacuum brazing has taken place, or this is done by vacuum brazing as well. The high temperature vacuum brazing process may be carried out in any useful way, wherein it is possible to use foil, powder or paste for making the necessary interconnections. In order to avoid high costs of the brazing process, it may be practical to make use of disposable ceramic strips and metal clips for holding the ceramic strips at edge positions on the stack 12.

(19) During operation of the recuperator 101, one fluid is made to flow through the internal fluid flow path of the cell 20, while another fluid is made to flow through the external fluid flow path of the cell 20. The heat exchange elements 50 have a function in enhancing heat exchange between the two fluids. In the first place, the heat exchange elements 50 constitute an enlargement of the surface at which heat exchange can take place. In the second place, the heat exchange elements 50 assist in spreading the fluids across the plates 22, 23. In the third place, the presence of the heat exchange elements 50 in the cell 20 contributes to the mechanical integrity of the cell 20, as the plates 22, 23 are not only interconnected along the periphery thereof, but may also be interconnected through the heat exchange elements 50. This aspect of the use of heat exchange elements 50 in the cell 20 is especially advantageous in view of the fact that this enables the cell 20 to withstand relatively high pressures at the position of the internal space thereof. The various wire coils 51 used in the cell 20 may be adjusted to specific operational circumstances, especially as far as the choice of material is concerned. Wire coils 51 which are arranged at a side of the cell 20 that may be expected to get very hot may be made of another material than wire coils 51 which are arranged at a colder side of the cell 20.

(20) The discrete spatial components used in the cell 20 for defining the heat exchange elements 50 do not necessarily need to comprise the wire coils 51 as shown. Alternative embodiments of the spatial components are feasible within the framework of the invention. For example, wire meshes may be used in the cell 20, wherein it may be so that dimensions of the wire meshes are chosen such that a layer 1, 2, 3 of heat exchange elements 50 can be realized by means of only one wire mesh. In general, the spatial components are designed so as to provide heat exchange elements 50 in a fluid flow path for interacting with a flow of fluid, wherein it is advantageous if the heat exchange elements 50 are shaped so as to realize an as large as possible heat exchange surface at minimal pressure loss across the cell 20.

(21) Besides the pair 21 of plates 22, 23 and the layers 1, 2, 3 of heat exchange elements 50, the cell 20 comprises a supply conduit 26 extending/projecting from the inlet 24. In the recuperator 101, the cell 20 is connected to the supply header 30 through the supply conduit 26, as can be seen in FIGS. 2 and 3. In the shown example, the supply conduit 26 comprises two distinctive portions, namely a bellows-shaped pipe portion 27 which is designed to compensate for heat expansion effects and to thereby avoid distortion effects, and a nozzle pipe portion 28 which diverges in the direction of the inlet 24. In the recuperator 101, the supply conduit 26 is connected to the supply header 30 through the bellows-shaped pipe portion 27 at the one side thereof, and to the plates 22, 23 at the position of the inlet 24 through the nozzle pipe portion 28 at the other side thereof. Both the bellows-shaped pipe portion 27 and the nozzle pipe portion 28 are of a basic, simple design so that the manufacturing process of the supply conduit 26 of the cell 20 can be fast and efficient. In a general sense, when the supply conduit 26 comprises something like at least one flexible portion 27 that is compressible and expandable in a direction in which the supply conduit 26 extends, which direction may also be referred to as a longitudinal direction of the supply conduit 26, the supply conduit 26 is suitable to compensate for heat expansion effects, wherein there is no need for complex measures involving high costs, a bulky/spacious design etc.

(22) At the position of the stack 11 of cells 20, the supply header 30 comprises a connection plate 31 having supply openings 32, as can be seen in FIG. 3. The connection plate 31 is shown separately in FIG. 7. The supply conduit 26 of each of the cells 20 is connected to the supply header 30 at a position of one of the supply openings 32 of the connection plate 31. At the position of the stack 11 of cells 20, a pipe-like appearance of the supply header 30 is obtained by means of a curved closure component 33 which is designed to be joined to the connection plate 31 along longitudinal edges thereof. A suitable connecting technique such as welding may be used for assembling the supply header 30. For the purpose of avoiding a situation in which the cells 20 are supported on the supply header 30 only through the supply conduit 26, which would put construction requirements on the supply conduit 26, a rack-like holder component 34 is arranged so as to extend from the connection plate 31 of the supply header 30 and to engage with edge portions of the stack 12 of plates 22, 23 and layers 1, 2, 3 of heat exchange elements 50.

(23) There is no need for compensating for heat expansion effects at both sides of the stack 11 of cells 20, and therefore, it is sufficient for the cells 20 to comprise a conduit 26 having a flexible portion 27 at only one side thereof, provided that the flexible portion 27 is designed to cover a complete possible displacement range of components. Hence, the stack 12 of plates 22, 23 and layers 1, 2, 3 of heat exchange elements 50 can be connected directly to the discharge header 40. In view thereof, the discharge header 40 comprises a connection plate 41 provided with slotted discharge openings 42. The connection plate 41 is shown separately in FIG. 8. Each of the cells 20 is received in the connection plate 41 at a position in which a discharge opening 42 is open to the outlet 25 of the cell 20. At the position of the stack 11 of cells 20, a pipe-like appearance of the discharge header 40 is obtained by means of a curved closure component 43 which is designed to be joined to the connection plate 41 along longitudinal edges thereof. A suitable connecting technique such as welding may be used for assembling the discharge header 40. In the shown example, both the connection plate 41 and the closure component 43 are designed as half pipes so that a complete pipe is obtained when the connection plate 41 and the closure component 43 are put together.

(24) As mentioned earlier, the recuperator 101 is intended to be used as a gas-to-gas heat exchanger and is particularly suitable for application in the context of a micro gas turbine. FIG. 9 shows a scheme of various components of a micro gas turbine 100, wherein fluid flows are indicated by means of large arrows. The micro gas turbine 1 may be dimensioned to generate up to 30 kW electric power, for example. Besides the recuperator 101, the micro gas turbine 100 comprises a compressor 102, a turbine 103, a combustor 104, a high speed generator 105, a heat exchanger 106 and an exhaust 107. The high speed generator 105 is arranged on a common shaft 108 of the compressor 102 and the turbine 103. When the micro gas turbine 100 is operated, air is input to the compressor 102 and fuel is input to the combustor 104. The compressor 102 acts to compress the air and to thereby pressurize the air to about 3 bar. The compressed air is supplied to the recuperator 101 where it is pre-heated under the influence of heat exchange with exhaust gas from the turbine 103. The compressed air is supplied to the combustor 104 which is configured and arranged to output hot gas under the influence of heat generated by fuel combustion. The hot pressurized gas is expanded in the turbine 103, on the basis of which mechanical power is obtained that is used for powering both the compressor 102 and the high speed generator 105. In the process, the common shaft 108 performs a rotary movement as indicated by means of a small bent arrow.

(25) Exhaust gas from the turbine 103 is supplied to the recuperator 101 for heating compressed air from the compressor 102, as mentioned. After having passed the recuperator 101, the gas from the turbine 103 is made to flow through the heat exchanger 106 and finally through the exhaust 107. The heat exchanger 106 serves to heat a suitable medium such as water. Thus, output of the micro gas turbine 100 is realized at the heat exchanger 106, as mentioned, and the high speed generator 105, wherein it is noted that the latter is designed to be used to convert mechanical power to electric power.

(26) In the recuperator 101, the low pressure hot gas from the turbine 103 is made to flow through the external fluid flow path of the various cells 20, whereas the high pressure cold air from the compressor 102 is made to flow through the internal fluid flow path of the various cells 20. In this respect, it is noted that the relatively hot side of the recuperator 101 is at the discharge header 40, whereas the relatively cold side of the recuperator 101 is at the supply header 30. In view thereof, it is advantageous to have the means for compensating for heat expansion at the side of the supply header 30, as is the case in the shown example where a bellows-shaped pipe portion 27 is incorporated in a supply conduit 26 of the cells 20. The same is applicable to the nozzle pipe portion 28 of the supply conduit 26 of the cells 20.

(27) Thus, the recuperator 101 serves to heat up the air from the compressor 102, that is to be supplied to the turbine 103 after having passed the combustor 104, and to cool down the gas from the turbine 103, wherein the air from the compressor 102 is transported to the cells 20 of the recuperator 101 through the supply header 30 and transported away from the cells 20 through the discharge header 40. In the context of the micro gas turbine 100, a temperature at the turbine side of the recuperator 101 may be as high as 750°, or even 800° C. or higher, and both the temperature differential and the pressure differential across the recuperator 101 are relatively high as well, in view of the fact that a temperatures at the compressor side of the recuperator 101 may be about 250° C., and the fact that the pressure of the air from the compressor 102 may be about 3 bar whereas the pressure of the gas from the turbine 103 is at ambient pressure. It appears in practice that the recuperator 101 of the design as shown in the figures and described in the foregoing maintains its functionality under the extreme circumstances, while realizing an efficient heat exchange process. Thus, the invention provides a recuperator 101 of a relatively uncomplicated design which is still capable of performing the heat exchange process as desired and meeting the various requirements as applicable to the process, and which has a lifetime that is at least comparable to that of a recuperator of a conventional design, such as the recuperator known from WO 2006/072789 A1. Compared to a recuperator of conventional design, a reduction of costs of more than 50% can be realized.

(28) It will be clear to a person skilled in the art that the scope of the invention is not limited to the examples discussed in the foregoing, but that several amendments and modifications thereof are possible without deviating from the scope of the invention as defined in the attached claims.

(29) Also, it will be clear to a person skilled in the art that various aspects of the invention are independently applicable. In this respect, it is noted that the following items are feasible: a cell 20 for use in a heat exchanger 101, including a pair 21 of mutually spaced-apart plates 22, 23 which is configured and arranged to define an internal fluid flow path of the cell 20, particularly between two inner surfaces of the plates 22, 23 facing each other, and an external fluid flow path of the cell 20, particularly at two outer surfaces 22a, 23a of the plates 22, 23 facing away from each other, wherein the plates 22, 23 are connected to each other along the periphery thereof, except at positions where at least one inlet 24 to and at least one outlet 25 from the internal fluid flow path are located, and wherein a plurality of heat exchange elements 50 is arranged in each of the fluid flow paths, the plurality of heat exchange elements 50 of a fluid flow path being defined by at least one discrete spatial component 51 incorporating at least a portion of the plurality of heat exchange elements 50 and being at least connected to an adjacent one of the plates 22, 23; a heat exchanger 101 comprising a stack 11 of cells 20 and a housing 10 enclosing the stack 11 of cells 20, each of the cells 20 including a pair 21 of mutually spaced-apart plates 22, 23 which is configured and arranged to define an internal fluid flow path of the cell 20, particularly between two inner surfaces of the plates 22, 23 facing each other, and an external fluid flow path of the cell 20, particularly at two outer surfaces 22a, 23a of the plates 22, 23 facing away from each other, wherein the plates 22, 23 are connected to each other along the periphery thereof, except at positions where at least one inlet 24 to and at least one outlet 25 from the internal fluid flow path are located, and wherein a plurality of heat exchange elements 50 is arranged in each of the fluid flow paths, the heat exchanger 101 comprising a discharge header 40 for discharging fluid from the internal fluid flow path of the respective cells 20, the discharge header 40 comprising a connection plate 41 provided with slotted discharge openings 42, the connection plate 41 being arranged against the cells 20, and each of the slotted discharge openings 42 being aligned with an outlet 25 of an internal fluid flow path of a cell 20; a heat exchanger 101 comprising a stack 11 of cells 20 and a housing 10 enclosing the stack 11 of cells 20, each of the cells 20 including a pair 21 of mutually spaced-apart plates 22, 23 which is configured and arranged to define an internal fluid flow path of the cell 20, particularly between two inner surfaces of the plates 22, 23 facing each other, and an external fluid flow path of the cell 20, particularly at two outer surfaces 22a, 23a of the plates 22, 23 facing away from each other, wherein the plates 22, 23 are connected to each other along the periphery thereof, except at positions where at least one inlet 24 to and at least one outlet 25 from the internal fluid flow path are located, wherein a plurality of heat exchange elements 50 is arranged in each of the fluid flow paths, and wherein, in each of the cells 20, the plurality of heat exchange elements 50 of a fluid flow path is defined by at least one discrete spatial component 51 incorporating at least a portion of the plurality of heat exchange elements 50 and being at least connected to an adjacent one of the plates 22, 23. a heat exchanger 101 comprising a stack 11 of cells 20 and a housing 10 enclosing the stack 11 of cells 20, each of the cells 20 including a pair 21 of mutually spaced-apart plates 22, 23 which is configured and arranged to define an internal fluid flow path of the cell 20, particularly between two inner surfaces of the plates 22, 23 facing each other, and an external fluid flow path of the cell 20, particularly at two outer surfaces 22a, 23a of the plates 22, 23 facing away from each other, wherein the plates 22, 23 are connected to each other along the periphery thereof, except at positions where at least one inlet 24 to and at least one outlet 25 from the internal fluid flow path are located, wherein a plurality of heat exchange elements 50 is arranged in each of the fluid flow paths, and wherein each of the cells 20 comprises at least one supply conduit 26 extending from the at least one inlet 24 to the internal fluid flow path, the heat exchanger 101 comprising a supply header 30 for supplying fluid to the internal fluid flow path of the respective cells 20, the at least one inlet 24 to the internal fluid flow path of the respective cells 20 being connected to the supply header 30 through the at least one supply conduit 26 of the cells 20, the supply header 30 comprising a connection plate 31 having supply openings 32, and the at least one supply conduit 26 of the cells 20 being connected to the connection plate 31 at the position of a supply opening 32; a method of manufacturing a cell 20 for use in a heat exchanger 101, wherein two plates 22, 23 and a plurality of heat exchange elements 50 configured to extend from at least one surface 22a, 23a of the plates 22, 23 are provided and stacked so as to obtain a stack 12 including successively a first outer layer 1 including heat exchange elements 50, a first plate 22, at least one intermediate layer 2 including heat exchange elements 50, a second plate 23, and a second outer layer 3 including heat exchange elements 50, wherein connections between the plates 22, 23 and the heat exchange elements 50 are made so as to obtain a stacked entirety 12, wherein the plates 22, 23 are connected to each other along the periphery thereof, except at positions for having at least one inlet 24 to and at least one outlet 25 from an internal fluid flow path as defined between the plates 22, 23, wherein the stacked entirety 12 of two plates 22, 23 and layers 1, 2, 3 including heat exchange elements 50 is provided with at least one supply conduit 26 having at least one flexible portion 27, preferably a flexible portion 27 that is compressible and expandable in a direction in which the at least one supply conduit 26 extends, and wherein the at least one supply conduit 26 is connected to the stacked entirety 12 at the position of the at least one inlet 24 to the internal fluid flow path; a method of manufacturing a heat exchanger 101, wherein cells 20 are manufactured by providing two plates 22, 23 and a plurality of heat exchange elements 50 configured to extend from at least one surface 22a, 23a of the plates 22, 23, stacking the plates 22, 23 and the heat exchange elements 50 so as to obtain a stack 12 including successively a first outer layer 1 including heat exchange elements 50, a first plate 22, at least one intermediate layer 2 including heat exchange elements 50, a second plate 23, and a second outer layer 3 including heat exchange elements 50, making connections between the plates 22, 23 and the heat exchange elements 50 so as to obtain a stacked entirety 12, and connecting the plates 22, 23 to each other along the periphery thereof, wherein the cells 20 are arranged in a stack 11, wherein the stack 11 of cells 20 is enclosed in a housing 10, and wherein a discharge header 40 for discharging fluid from an internal fluid flow path as defined between the plates 22, 23 of the respective cells 20 is made by providing a connection plate 41 having slotted discharge openings 42, arranging the connection plate 41 against the cells 20 and aligning each of the slotted discharge openings 42 with an outlet 25 of an internal fluid flow path of a cell 20, providing a closure component 43, and interconnecting the connection plate 41 and the closure component 43 so as to form a pipe-like entirety; and a method of manufacturing a heat exchanger 101, wherein cells 20 are manufactured by providing two plates 22, 23 and a plurality of heat exchange elements 50 configured to extend from at least one surface 22a, 23a of the plates 22, 23, stacking the plates 22, 23 and the heat exchange elements 50 so as to obtain a stack 12 including successively a first outer layer 1 including heat exchange elements 50, a first plate 22, at least one intermediate layer 2 including heat exchange elements 50, a second plate 23, and a second outer layer 3 including heat exchange elements 50, making connections between the plates 22, 23 and the heat exchange elements 50 so as to obtain a stacked entirety 12, connecting the plates 22, 23 to each other along the periphery thereof, providing the stacked entirety 12 of two plates 22, 23 and at least three discrete spatial components 51 with at least one supply conduit 26, and connecting the at least one supply conduit 26 to the stacked entirety 12 at the position of the at least one inlet 24 to the internal fluid flow path, wherein the cells 20 are arranged in a stack 11, wherein the stack 11 of cells 20 is enclosed in a housing 10, and wherein a supply header 30 for supplying fluid to an internal fluid flow path as defined between the plates 22, 23 of the respective cells 20 is made by providing a connection plate 31 having supply openings 32, connecting the at least one supply conduit 26 of the cells 20 to the connection plate 31 at the position of a supply opening 32, providing a closure component 33, and interconnecting the connection plate 31 and the closure component 33 so as to form a pipe-like entirety.

(30) A possible summary of the invention reads follows. A heat exchanger 101 that is suitable to be used as a recuperator in a micro gas turbine 100 comprises a stack 11 of cells 20. Each of the cells 20 includes a pair 21 of mutually spaced-apart plates 22, 23 and layers 1, 2, 3 of heat exchange elements 50 arranged at the outer surfaces 22a, 23a of the plates 22, 23 and between the plates 22, 23. Each of the layers 1, 2, 3 of heat exchange elements 50 preferably comprises at least one discrete spatial component 51 incorporating a plurality of heat exchange elements 50. For example, each of the layers 1, 2, 3 of heat exchange elements 50 may comprise a number of wire coils 51 or a wire mesh. Further, both a supply header 30 and a discharge header 40 of the heat exchanger 101 are preferably composed of only two components 31, 33; 41, 43 at the position of the stack 11 of cells 20. Means for compensating for heat expansion effects are of uncomplicated design as well and may comprise a bellows-shaped pipe portion 27 of a supply conduit 26.

(31) In a general sense, the invention provides a heat exchanger 101 that is suitable to be used as a recuperator in a micro gas turbine 100, while still being of relatively uncomplicated design. As an advantageous consequence, a method of manufacturing the heat exchanger 101 is relatively uncomplicated as well and does not involve expensive tooling. Further, the invention allows for building a high temperature recuperator from materials being lower grade materials in comparison to materials commonly applied in view of the temperatures to be expected during the recuperator's lifetime, as the invention provides a recuperator of a design with improved internal strength and heat resistance. In practice, it may even be so that stainless steel may be used at areas where normally a high grade material such as Inconel would be required. The invention provides measures on the basis of which it is possible to have structural features intended to compensate for thermal expansion effects and to create stress relief only at the relatively cold side of the heat exchanger 101, thereby providing more design freedom in respect of choice of material, and also more possibilities of using standard components and/or manufacturing components from readily available sheets, while a need for complex shapes from special heat resistant material is avoided/minimized.