JP2004132696A - Regenerator for stirling engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a regenerator for a Stirling engine having high heat storage performance capable of reducing manufacturing costs. <P>SOLUTION: Screen printing is applied to a surface of a resin film 2 by using photo-curing ink to form a plurality of protruding ribs 3. Three mutually independent regenerator cores 1a, 1b, and 1c with equal sizes are manufactured by cylindrically winding the resin film 2. The regenerator cores 1a, 1b and 1c are joined in an axial direction of a cylinder. The ribs 3 of the resin film 2 surface are provided in parallel with the axial direction of the cylinder at equal intervals. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a regenerator for a Stirling engine, and more particularly, to a regenerator for a Stirling engine capable of reducing production cost and improving engine efficiency by improving a method and a structure of the regenerator.

As a conventional regenerator for a Stirling engine, for example, as shown in FIG. 9 (b), an ultrafine spacer 4 is adhered to the surface of a resin film 2 at regular intervals, and irregularities are provided on the surface of the resin film 2. As shown in FIG. 9 (a), there is one that is wound into a cylindrical shape so that a cavity having a ring-shaped cross section is formed therein. FIG. 8 is a side sectional view of an example of a free piston type Stirling refrigerator incorporating the regenerator 1. First, the operation of the Stirling refrigerator will be described.

As shown in FIG. 8, the free-piston Stirling refrigerator includes a cylinder 8 in which a working gas such as helium is sealed, a displacer 7 and a piston 5 that partition the inside of the cylinder 8 into an expansion space 10 and a compression space 9. A linear motor 6 for reciprocating the piston 5, a heat absorber 14 provided on the expansion space 10 side for removing heat from the outside, and a radiator 13 provided on the compression space 9 side for releasing heat to the outside. are doing. In FIG. 8, reference numerals 11 and 12 denote plate springs that support the displacer 7 and the piston 5 and reciprocate the displacer 7 and the piston 5 by elastic force. 15 is a heat exchanger for heat dissipation, and 16 is a heat exchanger for heat absorption. These serve to promote the exchange of heat with the outside of the refrigerator. The regenerator 1 is provided between the heat exchanger for heat radiation 15 and the heat exchanger 16 for heat absorption.

With the above configuration, when the linear motor 6 is driven, the piston 5 moves upward in the cylinder 8 accordingly, and the working gas in the compression space 9 is compressed. Although the temperature of the working gas rises due to the compression, it is cooled by being exchanged with the outside air from the radiator 13 through the heat radiating heat exchanger 15, so that this process is an isothermal compression change. The working gas compressed by the piston 5 in the compression space 9 flows into the regenerator 1 by pressure and is sent into the expansion space 10. At that time, the amount of heat of the working gas is stored in the resin film 2 constituting the regenerator 1, and the temperature of the working gas drops.

(4) The high-pressure working gas that has flowed into the expansion space 10 expands when the displacer 7 that reciprocates with the piston 5 maintaining a predetermined phase difference moves downward. At this time, although the temperature of the working gas falls, the heat is absorbed by absorbing the heat of the outside air from the heat absorber 14 via the heat exchanger 16 for heat absorption, so that this process is an isothermal expansion change. Eventually, the displacer 7 starts to rise, and the working gas in the expansion space 10 passes through the regenerator 1 and returns to the compression space 9 again. At that time, the amount of heat stored in the regenerator 1 is given to the working gas, and the working gas rises in temperature. This series of Stirling cycles is repeated by the reciprocating motion of the driving unit, so that the heat absorber 14 absorbs heat from the outside air, so that the temperature gradually decreases.

As described above, in the Stirling refrigerator in which the working gas is reciprocated between the compression space 9 and the expansion space 10 through the regenerator 1 to extract the cold heat from the heat absorber 14, the high-temperature working gas compressed by the regenerator 1 The amount of heat stored in the regenerator 1 is increased, and the amount of heat is given to the expanded low-temperature working gas to recover the cold heat. Leads to improvement.

However, in the above-described configuration of the conventional regenerator for a Stirling engine, since the spacers 4 are attached one by one to the surface of the resin film 2 at regular intervals, a great amount of time and labor are required for manufacturing, and the cost is extremely high. There was a problem of becoming expensive. When the working gas passes through the inside of the regenerator 1, as shown in FIG. 10, the working gas separates from the surface of the wound resin film 2 and is substantially in the center as it goes from the entrance of the regenerator to the inside. Due to the bias (the boundary layer develops), there has been a problem that the heat transfer efficiency between the working gas and the regenerator 1 is reduced.

An object of the present invention is to provide a regenerator for a Stirling engine that overcomes the above-mentioned conventional disadvantages, has high heat storage performance, and can reduce the cost by simplifying the manufacturing method.

In order to achieve the above object, the Stirling engine regenerator of the present invention is disposed between the compression space and the expansion space of the Stirling engine, and serves as a flow path of a working gas that reciprocates between the compression space and the expansion space. In a regenerator for a Stirling engine that recovers heat from the working gas, at least two or more cores obtained by winding a resin film having a plurality of ribs formed on its surface in a cylindrical shape, the ribs are formed in the axial direction of the cylinder. They are stitched together.

リ ブ The ribs are provided at equal intervals in parallel with the axial direction of the cylinder.

Further, another regenerator for a Stirling engine of the present invention is disposed between the compression space and the expansion space of the Stirling engine, and serves as a flow path of a working gas reciprocating between the compression space and the expansion space. A regenerator for a Stirling engine that recovers heat, wherein a resin film on which a plurality of ribs are formed is wound in a cylindrical shape, wherein the ribs have a certain angle of inclination with respect to the axial direction of the cylinder. Is what it is.

Since the present invention has the above configuration, at least two or more cores wound with a resin film having a plurality of ribs, by joining the ribs so that the ribs are shifted, when the working gas passes through the regenerator, The boundary layer that develops from the regenerator entrance is interrupted at the seam between the cores. As a result, the heat transfer efficiency between the working gas and the regenerator can be improved, and the heat storage performance of the regenerator can be improved.

Also, since the ribs are provided at equal intervals in the axial direction of the cylinder, even if a large amount of resin film is produced, variations in performance among the regenerator cores can be extremely reduced.

In addition, a resin film having a plurality of ribs is wound in a cylindrical shape, and the ribs have a certain angle of inclination with respect to the axial direction of the cylinder. It is formed. Then, the gas passing through the gap collides with the oblique rib protruding from the resin film, whereby the flow is disturbed. Therefore, since the boundary layer developed from the entrance of the regenerator is interrupted by the rib, the efficiency of heat transfer between the working gas and the resin film is improved. As a result, a significant improvement in the heat storage performance of the regenerator can be expected in combination with an increase in the heat transfer area due to the protruding ribs. Therefore, for example, by providing the ribs by screen printing or thermoforming, a regenerator for a Stirling engine having stable heat storage performance can be obtained at low cost.

第 A first embodiment of the present invention will be described with reference to the drawings. FIG. 1A is a perspective view showing a configuration of a regenerator for a Stirling engine used in the present embodiment, and FIG. 1B is an enlarged view of a main part thereof. The regenerator for a Stirling engine according to the present invention is different from the above-described conventional regenerator only in the manufacturing method and the structure. Therefore, in the following embodiments, members common to the conventional products are denoted by the same reference numerals, Detailed description is omitted.

(1) As shown in FIG. 1 (b), ribs 3 are provided on the surface of the resin film 2 at regular intervals and parallel to each other. Then, the resin film 2 is wound into a cylindrical shape as shown in FIG. 1A, whereby the regenerator 1 for a Stirling engine is manufactured. In the regenerator 1 according to the present embodiment, the ribs 3 are provided in parallel with the axial direction of the regenerator 1 having a substantially cylindrical shape as shown in the drawing. Therefore, the regenerator 1 used in the present embodiment has a local structure similar to that of the regenerator described in the related art shown in FIG. 9, and thus has little difference in heat storage performance from the conventional regenerator.

However, in the present invention, since the unevenness is provided on the surface of the resin film 2 by the ribs 3, the regenerator 1 can be manufactured inexpensively and easily as compared with the conventional method of attaching the spacer. The material of the resin film 2 is preferably polyethylene terephthalate (PET) or polyimide in consideration of various conditions such as high specific heat, low thermal conductivity, high heat resistance, and low moisture absorption. Can be used. The ribs 3 may be formed on the surface of the resin film 2 by applying a photocurable ink to the surface of the resin film 2 and then performing screen printing or pressing a heated metal mold against the surface of the resin film 2. There is a thermoforming method and the like.

A second embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a perspective view showing a configuration of a regenerator for a Stirling engine used in the present embodiment. As shown in FIG. 2, the regenerator 1 according to the present embodiment is configured by joining three independent substantially cylindrical regenerator cores 1a, 1b, and 1c having the same size in the axial direction of the cylinder. Each of the regenerator cores is formed by winding a resin film 2 provided with ribs 3 at equal intervals and parallel to the axial direction of the cylinder in a cylindrical shape. Are set equal.

Meanwhile, in the regenerator not divided into the cores described in the conventional and first embodiments, when the working gas passes through the inside of the regenerator along the flow path indicated by the arrow in the figure, the boundary layer (FIG. 10) ), Which has led to a decrease in the efficiency of heat transfer between the working gas and the regenerator.

However, in the regenerator 1 for a Stirling engine having a configuration in which the cylindrical short regenerator cores 1a, 1b, and 1c are joined in the axial direction of the cylinder as in the present embodiment, the joint between the cores is not shown. As described above, the position of the rib 3 is shifted. Accordingly, the working gas flowing into the regenerator 1 from the direction of the arrow in FIG. 2 flows between the ribs 3 and 3 of the regenerator core 1a and flows into the next regenerator core 1b. At this time, since the gas collides with the rib 3 of the regenerator core 1b and the flow is disturbed, the development of the boundary layer is interrupted at this portion. The same occurs when the working gas moves from the regenerator core 1b to the regenerator core 1c.

As described above, when the working gas passes through the inside of the regenerator 1, it moves from one core to the other core, so that the development of the boundary layer is suppressed at the seam between the cores. And the heat storage performance of the regenerator 1 itself is considerably improved as compared with the case where the regenerator 1 is not divided into cores as in the first embodiment. Although FIG. 2 shows a case where there are three regenerator cores, the number of regenerator cores may be further increased. In this case, a further improvement in the heat storage performance of the regenerator 1 can be expected.

３A third embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a perspective view illustrating a configuration of a Stirling engine regenerator used in the present embodiment. As shown in FIG. 3, the regenerator 1 for a Stirling engine according to the present embodiment comprises three independent substantially cylindrical regenerator cores 1a, 1b, and 1c having the same size as in the second embodiment. The expansion space and the compression space (not shown) are connected to the opening sides of the regenerator cores 1a and 1c at both ends, respectively.

In addition, each regenerator core is formed by winding a resin film 2 provided with ribs 3 at regular intervals and parallel to the axial direction of the cylinder in a cylindrical shape. The interval is set so as to gradually increase as it approaches the expansion space as shown in the figure. That is, the interval between the ribs formed on each core is increased in the order of 1c, 1b, and 1a.

Now, when the working gas flows from the compression space side into the regenerator 1 as shown by the arrow in FIG. 3, the working gas passes through the inside of the regenerator 1 due to the heat storage action of the regenerator 1. As the regenerator 1 loses heat and approaches the expansion space, the temperature gradually decreases. As the temperature of the gas decreases, the density increases and the fluidity decreases. Therefore, the working gas in the regenerator 1 becomes more difficult to flow smoothly as it approaches the expansion space. Therefore, as in the present embodiment, by gradually increasing the interval between the ribs 3 of the regenerator 1 as the space approaches the expansion space, the gas flow resistance becomes substantially uniform over the entire regenerator 1 and the gas flow Smoothness and uniform gas flow distribution. As a result, the heat storage performance of the regenerator 1 is further improved in combination with the effect of suppressing the boundary layer by joining the regenerator cores.

４A fourth embodiment of the present invention will be described with reference to the drawings. FIG. 4 is a perspective view showing a configuration of a regenerator for a Stirling engine used in the present embodiment. As shown in FIG. 4, a front rib 3a and a rear rib 3b having a certain inclination are provided on both the front and back surfaces of the resin film 2, and the resin film 2 is wound into a cylindrical shape to form a regenerator 1. Is formed. Here, the inclination directions of the front rib 3a and the back rib 3b provided on both surfaces of the resin film 2 are set to be opposite to each other with respect to the axial direction of the cylinder. Therefore, when this resin film 2 is wound, a contact point where the front rib 3a and the back rib 3b cross each other is formed, and a gap serving as a gas flow path is secured between the films 2 and 2.

A compression space and an expansion space (not shown) are connected to both ends of the regenerator 1, respectively. The working gas filled in the cylinder of the Stirling refrigerator is supplied to the compression space and the expansion space via the regenerator 1. To and fro. At this time, the gas flowing in the regenerator 1 collides with ribs 3a and 3b protruding from the front and back of the resin film 2 as shown in FIG. Therefore, since the boundary layer developed from the entrance of the regenerator 1 is interrupted by the ribs 3a and 3b, the heat transfer efficiency between the working gas and the resin film 2 is improved. As a result, a significant improvement in the heat storage performance of the regenerator 1 can be expected in combination with an increase in the heat transfer area due to the protruding ribs 3a and 3b.

Table 1 shows the specifications of a ribbed resin film that was prototyped to produce a Stirling engine regenerator suitably used in the present embodiment. As shown in Table 1, polyethylene terephthalate was used as a material for the resin film. The ribs were formed on both surfaces of the resin film by applying a UV ink to the surface of the resin film and then performing screen printing. Thereby, a rib having a height of 35 μm, a width of 100 μm, and an inclination of 15 ° with respect to the winding direction was formed on the resin film.

By the way, as an index for evaluating the heat storage performance of a regenerator for a Stirling engine, a regenerator efficiency η represented by the following equation is usually used.
η = (Thin-Thout) / (Thin-Tcin)
= (Tcout-Tcin) / (Thin-Tcin) (1)
Here, Thin and Thout are the temperature immediately before the working gas compressed in the compression space flows into the regenerator and the temperature of the working gas immediately after flowing out of the regenerator into the expansion space. Further, Tcin and Tcout are the temperature of the working gas immediately before flowing into the regenerator from the expansion space and the temperature of the working gas immediately after flowing into the compression space from the regenerator, respectively.

In a Stirling engine, Thin> Thout, Tcout> Tcin, and Thin> Tcin hold, and the denominator of the above equation (1) does not become smaller than the numerator. Therefore, the regenerator efficiency η is in the range of 0 <η ≦ 1. Is the value included in. The greater the regenerator efficiency η (approaching 1), the more efficiently heat transfer with the working gas is performed in the regenerator, and it is closer to an ideal Stirling cycle with less heat loss.

Therefore, a prototype of a regenerator for a Stirling engine was manufactured by winding a resin film having the specifications shown in Table 1 into a cylindrical shape, and this regenerator was disposed in a cylinder of a Stirling refrigerator to vary the working gas. The regenerator efficiency η when reciprocating between the compression space and the expansion space at the reciprocating flow rate G (L / m) was measured. For comparison, a regenerator according to the related art (see FIG. 9) made of a resin film with a spacer attached was similarly evaluated. FIG. 6 shows the results. As can be seen from FIG. 6, the regenerator according to the present embodiment has higher regenerator efficiency than the conventional regenerator at any reciprocating flow rate, and has better heat storage performance than the conventional regenerator. Was done.

５A fifth embodiment of the present invention will be described with reference to the drawings. FIG. 7 is a perspective view showing a configuration of a regenerator for a Stirling engine used in the present embodiment. As shown in FIG. 7, in the present embodiment, the inclination angles of the front and rear ribs 3 a, 3 b provided on the resin film 2 constituting the regenerator 1 with respect to the axial direction of the cylinder gradually increase in proportion to the expansion space. It has been changed to be smaller.

作 動 As described above, the closer to the expansion space, the lower the temperature of the working gas and the higher the density. By decreasing the inclination of the ribs stepwise in accordance with the increase in the density of the working gas, the flow resistance to the gas passing through the regenerator 1 is reduced, the gas flow is smoothed, and the gas flow rate distribution is reduced. Can be easily realized. Although FIG. 7 shows a case where the rib angle is changed in three stages, the number of stages in which the angle is changed may be further increased. In this case, the effect described above becomes more remarkable.

FIG. 1A is a perspective view illustrating a configuration of a regenerator for a Stirling engine according to a first embodiment of the present invention. FIG. 2B is an enlarged view of a main part in FIG. It is a perspective view showing composition of a regenerator for a Stirling engine which is a 2nd embodiment of the present invention. It is a perspective view showing composition of a regenerator for a Stirling engine which is a 3rd embodiment of the present invention. It is a perspective view showing composition of a regenerator for a Stirling engine which is a 4th embodiment of the present invention. It is explanatory drawing which shows the flow state of the gas which passes inside the regenerator for Stirling engines which is 4th Embodiment of this invention. It is a figure showing a result of a performance test of a regenerator for a Stirling engine which is a 4th embodiment of the present invention. It is a perspective view showing the composition of the regenerator for Stirling engines which is a 5th embodiment of the present invention. It is a side sectional view showing the composition of the Stirling refrigerator provided with the Stirling regenerator concerning the present invention. (A) It is a perspective view which shows the structure of the conventional regenerator for Stirling engines. (B) It is a principal part enlarged view in FIG.9 (a). It is explanatory drawing which shows the flow state of the gas which passes through the inside of the conventional regenerator for Stirling engines.

Explanation of reference numerals

1 Regenerator 1a, 1b, 1c for Stirling engine Regenerator core 2 Resin film 3 Rib 3a Front rib 3b Back rib 4 Spacer 5 Piston 6 Linear motor 7 Displacer 8 Cylinder 9 Compression space 10 Expansion space 11, 12 Leaf spring 13 Radiator 14 Heat absorber 15 Heat exchanger for heat radiation 16 Heat exchanger for heat absorption

Claims (3)

A Stirling engine regenerator that is disposed between the compression space and the expansion space of the Stirling engine and serves as a working gas flow path that reciprocates between the compression space and the expansion space, and that recovers heat from the working gas. A regenerator for a Stirling engine, characterized in that at least two or more cores formed by winding a resin film having a plurality of ribs into a cylindrical shape are joined so that the ribs are displaced in the axial direction of the cylinder. 2. The regenerator for a Stirling engine according to claim 1, wherein the ribs are provided at equal intervals in parallel with the axial direction of the cylinder. A Stirling engine regenerator disposed between the compression space and the expansion space of the Stirling engine and serving as a flow path of a working gas reciprocating between the compression space and the expansion space, and recovering heat from the working gas. A regenerator for a Stirling engine, wherein a resin film on which a rib is formed is wound into a cylindrical shape, wherein the rib has a certain angle of inclination with respect to the axial direction of the cylinder.

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