JP3677551B2

JP3677551B2 - Regenerative heat exchanger

Info

Publication number: JP3677551B2
Application number: JP2002366362A
Authority: JP
Inventors: 澄香川; 英一瀧澤
Original assignee: 防衛庁技術研究本部長
Priority date: 2002-12-18
Filing date: 2002-12-18
Publication date: 2005-08-03
Anticipated expiration: 2022-12-18
Also published as: JP2004198020A

Description

【０００１】
【発明の属する技術分野】
本発明は、スターリングエンジンやスターリング冷凍機、ビィルミエサイクル機器、パルスチューブ冷凍機、熱音響機器を始めとする熱再生機構を有する機関、並びに再生式ガスタービンの蓄熱式熱交換器に関する。
【０００２】
【従来の技術】
図９乃至図１１は従来の蓄熱式熱交換器を概略的に示した図であって、金網、発泡金属、マット状金属繊維、スプリングメッシュによる積層形（図１０参照）、細管、ハニカム、ヘリパック、ねじり線による配列形（図１１参照）、綿状金属繊維、ペブル（粒子）によるパック形（図１２参照）がある。積層形は比表面積が大きく、作動ガスとの間の熱伝達率も高く、かつ、流動損失もそれほど大きくなく、配列形は流動損失をかなり低減できるが、比表面積が小さく、熱伝達率も低く、パック形は比表面積が大きく流動損失の調整も可能であるが、２つの性能を両立させる事は難しく、取扱い性が悪い。したがって、性能的には積層形が優れており、スターリングエンジンおよびスターリング冷凍機の実機試験において積層金網の優位性が実証され、多くの機関に使用されている。
【０００３】
【発明が解決しようとする課題】
前記のような積層金網を蓄熱式熱交換器に利用する場合に、金網を成形する際に生じる金網の歪み、端部のほつれ、低い加工精度により、積層する際の取扱い性は非常に悪く、価格が高くなる欠点があり、金網の歪み、端部のほつれ、低い加工精度により、機関性能を低下させる。また、価格を考慮すると金網は既製品を利用する事になり、線径や線のピッチ、線の素材が決まってしまう。
【０００４】
それは、金網が細い金属線で織込まれているので、既製の広い金網のシートから小さな径（通常５〜９cm）にプレス加工等で打ち抜いて成型すると、金網が平にならず歪んでしまう。これをケーシングに収まるように積層（通常３００〜５００枚程度）する際に非常に手間がかかり、さらには金網間に隙間が生じて、無効容積が増加して圧縮比が低下して機関性能を低下させる。また、加工された端部はほつれやすく、ほつれた金属線は組み立て性を著しく低下させるばかりではなく、ほつれの部分でケーシングと積層金網の間に隙間が生じて、その隙間を作動ガスの一部が漏れ通って熱交換器を通過しない事で、機関効率を低下させる。また、プレス加工等で打ち抜き成型する場合は、細い金属線を種々の方向から切断する事になり、加工精度が悪くなって、組み立て性が悪く、かつ、ケーシングと積層金網の間に隙間が生じて、その隙間を作動ガスの一部が漏れ通って積層金網内を通過しない事で、機関効率を低下させる。また、実際に使用される金網は既製品が多く、その線径、ピッチ、素材が決まっており、機関に最適な熱伝達、摩擦損失特性を得るように最適設計値の適用や調整ができない。
【０００５】
本発明は、前記従来の問題を解決するためになされたもので、その目的は、積層部材の歪み、端部のほつれを無くし、高い加工精度をもって、積層する際の取扱い性を良くし、価格を安くする事を可能とし、数値計算等による結果に基づいた最適設計にしたがって形状を決定する事で機関性能を向上させることが可能な蓄熱式熱交換器を提供する事にある。
【０００６】
【課題を解決するための手段】
前記の目的を達成するために本発明は、厚さ0.1 〜0.2 mm程度の金属薄板にエッチング（腐食液による侵食作用により金属を加工する方法）あるいは電鋳方式（電極により金属をベースパターン上に析出する方法）により多数の細孔を開け、この薄板の片面あるいは両面に細孔を結ぶ溝を設け、薄板の外周部には細孔をなくして高い寸法精度を得るようにした事を特徴とする。
また、機器に合わせて径方向あるいは長手方向の作動ガスの流れや熱交換量を調節できるように、細孔の径は場所によって異なるものとし、溝の位置、形状を変える事を特徴とする。
さらに、薄板の表面の材質を熱伝導率の低いものとして、蓄熱式再生器の高温側から低温側へ熱伝導による損失を低減する事を特徴とする。また金属薄板の外周部の厚さを、その内側よりも外周方向に連続して薄く形成して、金属薄板を積層した場合の接触による積層方向への熱伝導損失を低減したことを特徴としている。
【０００７】
【発明の実施の形態】
以下、発明の一実施例を図１及至図８に従い具体的に説明する。
蓄熱式熱交換器を構成する１枚の金属薄板は、図１に示すように、薄板１に細孔２を密に多く設けた構造となっている。なお、図２に示す細孔２は方形、千鳥配列（60度）になっているが、その他の円形など細孔の形、およびその他の細孔の配列（碁盤目配列）でも可能である。
細孔２の径およびピッチ等の寸法は、その蓄熱式熱交換器を適用する機器によって最適値を決めるが、３kW級スターリングエンジンの場合には穴の寸法は0.24×0.24mmから0.30×0.30mm、ピッチ0.44mm程度、板厚み0.1mm のもの500 枚程度積層したものを採用して、従来のメッシュシートを採用した構造に比較し、軸出力が約７〜15％、熱効率が約10〜20％向上（図９参照）した。
【０００８】
さらに、作動ガスが流れる際の流動損失を低減する目的で、図３に示すように、細孔２と細孔２を溝３で結ぶ事も可能である。この溝３は薄板１の両側に設ける事ができる。なお、溝３の配置、数、寸法は、その熱再生式熱交換器を適用する機器によって特有の最適値を有するが、上述の３kW級スターリングエンジンの場合には図のような配置として溝幅約0.12mm、深さ約0.06mmとした。
【０００９】
図４に示したように、蓄熱式熱交換器４内の流れ（スターリング機器の場合は往復流、ガスタービンの場合には一方向流あるいは対向流）がその構造上不均一の場合にはその流れを均一にする目的で、薄板５、６における細孔の大きさ及び配置は、薄板上の場所によって自由に設計、設置する事ができる。また、その細孔の大きさ及び配置が異なる薄板をそれぞれ積層することが可能である。
【００１０】
また、図５に示したように、蓄熱式熱交換器４内の流れがその構造上不均一の場合にはその流れを均一にする目的で、薄板７、８における細孔を結ぶ溝の寸法、配置は薄板上の場所によって変える事ができる。また、その溝の寸法、配置が異なる薄板をそれぞれ積層することが可能である。
【００１１】
また、図６に示したように薄板１の外周部９に、外周縁方向に連続して、細孔を有しない平滑面領域を設けて、薄板の加工精度を向上させ、作動ガスの漏れ損失を低減させる。一般に、金網の場合には７cmの外径に対して＋・− 0.1mmの寸法公差となるが、この発明の方式ではさらに精度をあげる事ができ、＋・− 0.029〜＋・−0.010 mmとすることができる。なお、図７の横断面図のように外周部９の厚みを外周縁方向に連続して一段薄くすることで、積層した場合の接触による積層方向への熱伝導損失を低減している。さらに、外周部９の縁に窪み10をつける事により、積層した時の薄板の回転方向が外観からの目視により容易に判断でき、位置合わせをすることができる。
【００１２】
なお、図８に示したように、薄板の表面を異なる性質を有する金属で形成して、熱伝導損失を低下したり、腐食を防ぐ事を可能とする。例えば、熱伝導率のよく、熱容量が大きい銅やニッケルなどの母材１２の表面に、熱伝導率の悪く耐食性の強いステンレス等の材料からなる表面材１３を複合させる事が可能である。また、薄板表面の荒さを数ミクロンから数百ミクロン程度に荒くしたり、溝のついていない面に数ミクロンから数百ミクロンの深さのスクラッチ（平行溝）加工やヘアライン（細い溝）加工を設けることで、薄板間の熱接触抵抗を増加させ、熱伝導損失を低下させることもできる。図８中のメッキ方法は母材のみで作成した薄板をメッキ処理したものである。
【００１３】
また、図６に示した薄板１の中央にある穴１１は積層する際に通し棒を通す穴であり、組み立て性を考慮したものである。この部分に穴をあけずに、圧着や接合用のつけしろとして使用する事ができる。また、この部分にも細孔を設けて、外周部を圧着や接合用のつけしろとして使用する事ができる。
【００１４】
薄板の片面のみに細孔を結ぶ溝を設けた場合には、その溝のある面を低温の作動ガスが流れる方向（または、一方向のみ作動ガスが流れる場合にはその方向）に向ける事で、作動ガスが流れる際に発生する摩擦を低減する事が可能である。３kW級スターリングエンジンでは低温側に溝付き面を向けて積層することで、作動ガスがこの熱交換器を流れる際に発生する摩擦による損失を５０W 低下する事ができた。また、積層する際に発生する熱伝導損失を低減する目的で、溝の付いた面を交互に（裏表に）組み合わせる事が可能である。
【００１５】
【発明の効果】
本発明の蓄熱式熱交換器によれば、積層部材の歪み、端部のほつれを無くし、高い加工精度をもって、積層する際の取扱い性を良くし、価格を安くする事を可能とし、数値計算等の結果により得られた最適設計値にしたがって細孔、溝の形状寸法を決定する事で機関性能を向上させることが達成される。
試作した本発明の蓄熱式熱交換器においては、従来品の積層金網と比較して伝熱特性を表すヌッセルト数が約２倍になり、伝熱特性が向上することを確認した。因に、本発明の蓄熱式熱交換器を用いる事で、３kW級スターリングエンジンの場合にはその軸出力が約７〜15％、熱効率が10〜20％向上（図９参照）したことを確認している。
【図面の簡単な説明】
【図１】本発明の一実施例による蓄熱式熱交換器の金属薄板を示した概略平面図である。
【図２】同金属薄板の細孔を示した概略拡大図である。
【図３】同金属薄板の細孔と細孔を結ぶ溝を示した概略拡大図である。
【図４】同金属薄板の細孔が部分的に異なる寸法、形状をもつ薄板を示した蓄熱式熱交換器の概略図である。
【図５】同金属薄板の細孔を結ぶ溝が部分的に異なる寸法、形状をもつ薄板を示した蓄熱式熱交換器の概略図である。
【図６】本発明の他の実施例による蓄熱式熱交換器の金属薄板を示した概略平面図である。
【図７】同一部の拡大断面図である。
【図８】本発明のさらに他の実施例による蓄熱式熱交換器の金属薄板を示した横断面図である。
【図９】本発明の一実施例による蓄熱式熱交換器の性能試験のデータを示すグラフ図である。
【図１０】従来の蓄熱式熱交換器の構成材料を示す要部の拡大図である。
【図１１】従来の蓄熱式熱交換器の他の構成材料を示す要部の拡大図である。
【図１２】従来の蓄熱式熱交換器の他の構成材料を示す要部の拡大図である。
【符号の説明】
１…薄板、２…細孔、３…薄板上の溝、４…蓄熱式熱交換器（ケース）、５…部分的に細孔の寸法、配置を変えた薄板、６…全体に細孔の寸法、配置を揃えた薄板、７…部分的に細孔を結ぶ溝の寸法、配置を変えた薄板、８…全体に細孔を結ぶ溝の寸法、配置を揃えた薄板、９…外周部、１０…外周部の窪み、１１…穴、１２…母材、１３…表面材[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine having a heat regeneration mechanism such as a Stirling engine, a Stirling refrigerator, a Virmier cycle device, a pulse tube refrigerator, a thermoacoustic device, and a regenerative gas turbine heat storage heat exchanger.
[0002]
[Prior art]
FIGS. 9 to 11 are diagrams schematically showing a conventional heat storage type heat exchanger, in which a metal net, a foam metal, a mat-like metal fiber, a spring mesh laminated type (see FIG. 10), a thin tube, a honeycomb, and a helipack. There are an array form by twist lines (see FIG. 11), a pack form by cotton metal fibers and pebble (particles) (see FIG. 12). The laminated type has a large specific surface area, a high heat transfer rate with the working gas, and the flow loss is not so large, and the arrangement type can significantly reduce the flow loss, but the specific surface area is small and the heat transfer rate is low. The pack type has a large specific surface area and the flow loss can be adjusted, but it is difficult to achieve both performances and the handling property is poor. Therefore, the laminated type is excellent in terms of performance, and the superiority of the laminated wire mesh has been demonstrated in actual machine tests of Stirling engines and Stirling refrigerators, and is used in many engines.
[0003]
[Problems to be solved by the invention]
When using a laminated wire mesh as described above for a heat storage type heat exchanger, due to distortion of the wire mesh that occurs when forming the wire mesh, fraying of the end, and low processing accuracy, the handleability when laminating is very poor, There is a disadvantage that the price is high, and the distortion of the wire mesh, fraying of the end, and low processing accuracy reduce the engine performance. Also, considering the price, the wire mesh uses ready-made products, and the wire diameter, wire pitch, and wire material are determined.
[0004]
That is, since the wire mesh is woven with a thin metal wire, if the sheet is punched into a small diameter (usually 5 to 9 cm) from a ready-made sheet of wide wire mesh by press working or the like, the wire mesh is not flat and is distorted. It takes a lot of labor when stacking the sheets so that they fit in the casing (usually about 300 to 500 sheets). Furthermore, gaps are formed between the wire meshes, the ineffective volume increases, the compression ratio decreases, and the engine performance decreases. Reduce. In addition, the processed end portion is easily frayed, and the frayed metal wire not only significantly reduces the assemblability, but also a gap is formed between the casing and the laminated wire mesh at the frayed portion, and this gap is part of the working gas. The engine efficiency is reduced by leaking through the heat exchanger. Also, when punching and forming by pressing, etc., thin metal wires will be cut from various directions, processing accuracy will deteriorate, assembly will be poor, and a gap will occur between the casing and the laminated wire mesh. Thus, part of the working gas leaks through the gap and does not pass through the laminated wire mesh, thereby reducing the engine efficiency. In addition, there are many ready-made wire meshes that are actually used, and their wire diameter, pitch, and material are determined, and optimum design values cannot be applied or adjusted to obtain optimum heat transfer and friction loss characteristics for the engine.
[0005]
The present invention has been made to solve the above-mentioned conventional problems, and its purpose is to eliminate the distortion of the laminated member and the fraying of the end portion, to improve the handleability at the time of lamination with high processing accuracy, and the price. It is possible to provide a regenerative heat exchanger that can improve engine performance by determining the shape according to an optimal design based on the result of numerical calculation or the like.
[0006]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present invention is to etch a thin metal plate having a thickness of about 0.1 to 0.2 mm (a method of processing a metal by an erosion action with a corrosive liquid) or an electroforming method (a metal is formed on a base pattern by an electrode). It is characterized in that a large number of pores are opened by a method of deposition), grooves are formed on one or both sides of this thin plate, and the outer periphery of the thin plate is free of pores to obtain high dimensional accuracy. To do.
Further, the diameter of the pores is different depending on the location, and the position and shape of the groove are changed so that the flow of the working gas in the radial direction or the longitudinal direction and the heat exchange amount can be adjusted according to the equipment.
Furthermore, the material of the surface of a thin plate is made into a thing with low heat conductivity, The loss by heat conduction is reduced from the high temperature side of a thermal storage type regenerator to the low temperature side, It is characterized by the above-mentioned. In addition, the thickness of the outer peripheral portion of the metal thin plate is formed continuously thinner than the inner side in the outer peripheral direction, and the heat conduction loss in the stacking direction due to contact when the metal thin plates are stacked is reduced. .
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS.
As shown in FIG. 1, one metal thin plate constituting the heat storage type heat exchanger has a structure in which many thin pores 2 are provided in the thin plate 1. The pores 2 shown in FIG. 2 have a square shape and a staggered arrangement (60 degrees), but other shapes such as other circular shapes and other pore arrangements (a grid arrangement) are also possible.
The diameters and pitches of the pores 2 are determined optimally depending on the equipment to which the heat storage type heat exchanger is applied. In the case of a 3kW class Stirling engine, the hole size is 0.24 x 0.24mm to 0.30 x 0.30mm. Compared to the conventional structure using a mesh sheet of about 500 sheets with a pitch of about 0.44mm and a plate thickness of 0.1mm, the shaft output is about 7-15% and the thermal efficiency is about 10-20. % Improvement (see FIG. 9).
[0008]
Furthermore, for the purpose of reducing the flow loss when the working gas flows, it is also possible to connect the pores 2 and 2 with grooves 3 as shown in FIG. The groove 3 can be provided on both sides of the thin plate 1. The arrangement, number, and dimensions of the grooves 3 have specific optimum values depending on the equipment to which the heat regenerative heat exchanger is applied. In the case of the above-described 3 kW class Stirling engine, the groove width is arranged as shown in the figure. The depth was about 0.12 mm and the depth was about 0.06 mm.
[0009]
As shown in FIG. 4, when the flow in the regenerative heat exchanger 4 (reciprocating flow in the case of a Stirling device, unidirectional flow or counterflow in the case of a gas turbine) is not structurally uniform, In order to make the flow uniform, the size and arrangement of the pores in the thin plates 5 and 6 can be freely designed and installed depending on the location on the thin plate. Moreover, it is possible to laminate | stack each thin plate from which the magnitude | size and arrangement | positioning of the pore differ.
[0010]
In addition, as shown in FIG. 5, when the flow in the regenerative heat exchanger 4 is non-uniform in structure, the dimension of the groove connecting the pores in the thin plates 7 and 8 is intended to make the flow uniform. The arrangement can be changed depending on the location on the sheet. Moreover, it is possible to laminate | stack the thin plate from which the dimension and arrangement | positioning of the groove | channel differ, respectively.
[0011]
Further, as shown in FIG. 6, a smooth surface region having no pores is provided continuously on the outer peripheral portion 9 of the thin plate 1 so as to improve the processing accuracy of the thin plate, and the working gas leakage loss Reduce. In general, in the case of a wire mesh, a dimensional tolerance of +/− 0.1 mm is obtained with respect to an outer diameter of 7 cm. However, the accuracy of the method of the present invention can be further increased to +/− 0.029 to +/− 0.010 mm. can do. As shown in the cross-sectional view of FIG. 7, the thickness of the outer peripheral portion 9 is continuously reduced in the direction of the outer peripheral edge, thereby reducing the heat conduction loss in the stacking direction due to contact when stacked. Furthermore, by providing the dent 10 at the edge of the outer peripheral portion 9, the rotation direction of the thin plate when laminated can be easily determined by visual observation from the appearance and can be aligned.
[0012]
As shown in FIG. 8, the surface of the thin plate is made of a metal having different properties, so that heat conduction loss can be reduced or corrosion can be prevented. For example, a surface material 13 made of a material such as stainless steel having a low thermal conductivity and strong corrosion resistance can be combined with the surface of a base material 12 such as copper or nickel having a high thermal conductivity and a large heat capacity. In addition, the surface roughness of the thin plate is roughened from several microns to several hundred microns, and scratches (parallel grooves) and hairlines (thin grooves) with a depth of several microns to several hundred microns are provided on the non-grooved surface. Thus, the thermal contact resistance between the thin plates can be increased, and the heat conduction loss can be reduced. The plating method in FIG. 8 is obtained by plating a thin plate made only of a base material.
[0013]
Moreover, the hole 11 in the center of the thin plate 1 shown in FIG. 6 is a hole through which a through rod is passed when laminating, and considers assemblability. Without making a hole in this part, it can be used as a margin for crimping or joining. Also, pores can be provided in this portion, and the outer peripheral portion can be used as a margin for crimping or joining.
[0014]
When a groove connecting pores is provided only on one side of the thin plate, the surface with the groove should be directed in the direction in which the low-temperature working gas flows (or in the direction in which working gas flows in only one direction). It is possible to reduce the friction generated when the working gas flows. In a 3kW class Stirling engine, by laminating with the grooved surface facing the low temperature side, the loss due to friction generated when the working gas flows through this heat exchanger could be reduced by 50W. In addition, for the purpose of reducing the heat conduction loss that occurs when laminating, it is possible to combine the grooved surfaces alternately (front and back).
[0015]
【The invention's effect】
According to the heat storage type heat exchanger of the present invention, it is possible to eliminate the distortion of the laminated member and fraying of the end, improve the handleability when laminating with high processing accuracy, reduce the price, and perform numerical calculation. The engine performance can be improved by determining the shape dimensions of the pores and grooves according to the optimum design values obtained from the above results.
In the heat storage type heat exchanger according to the present invention, the Nusselt number representing the heat transfer characteristics is approximately doubled as compared with the conventional laminated wire mesh, and it has been confirmed that the heat transfer characteristics are improved. By the way, by using the regenerative heat exchanger of the present invention, in the case of a 3kW class Stirling engine, it was confirmed that the shaft output was improved by about 7-15% and the thermal efficiency was improved by 10-20% (see Fig. 9). doing.
[Brief description of the drawings]
FIG. 1 is a schematic plan view showing a thin metal plate of a heat storage type heat exchanger according to an embodiment of the present invention.
FIG. 2 is a schematic enlarged view showing pores of the same metal thin plate.
FIG. 3 is a schematic enlarged view showing a groove connecting the pores of the same metal thin plate.
FIG. 4 is a schematic view of a regenerative heat exchanger showing a thin plate in which the pores of the metal thin plate have partially different sizes and shapes.
FIG. 5 is a schematic view of a heat storage heat exchanger showing a thin plate in which grooves connecting pores of the metal thin plate have partially different sizes and shapes.
FIG. 6 is a schematic plan view showing a thin metal plate of a regenerative heat exchanger according to another embodiment of the present invention.
FIG. 7 is an enlarged cross-sectional view of the same part.
FIG. 8 is a cross-sectional view showing a thin metal plate of a regenerative heat exchanger according to still another embodiment of the present invention.
FIG. 9 is a graph showing performance test data of a regenerative heat exchanger according to an embodiment of the present invention.
FIG. 10 is an enlarged view of a main part showing constituent materials of a conventional heat storage heat exchanger.
FIG. 11 is an enlarged view of a main part showing another constituent material of a conventional heat storage heat exchanger.
FIG. 12 is an enlarged view of a main part showing another constituent material of a conventional heat storage heat exchanger.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Thin plate, 2 ... Fine hole, 3 ... Groove on thin plate, 4 ... Regenerative heat exchanger (case), 5 ... Thin plate partially changing the size and arrangement of pores, 6 ... Whole pores Thin plate with the same dimensions and arrangement, 7... The dimension of the groove partially connecting the pores, the thin plate with a different arrangement, 8... The dimension of the groove connecting the pores with the whole, the thin plate with the same arrangement, 9. DESCRIPTION OF SYMBOLS 10 ... Depression of outer peripheral part, 11 ... Hole, 12 ... Base material, 13 ... Surface material

Claims

Heat storage heat exchange characterized by opening a large number of pores in a metal thin plate, laminating the metal thin plate, and forming the outer peripheral portion of the metal thin plate continuously thinner in the outer peripheral direction than the inner side. vessel.

The regenerative heat exchanger according to claim 1, wherein a groove is provided on one or both surfaces of the thin metal plate so as to connect the pores adjacent to each other in the surface direction .

The regenerative heat exchanger according to claim 1 or 2, wherein the shape and size of the pores opened in the thin metal plate are varied depending on the location on the thin metal plate.

The regenerative heat exchanger according to claim 2 or 3, wherein the shape and size of the groove provided in the metal thin plate are varied depending on the location on the metal thin plate.

The smooth surface which does not have a pore and a groove | channel was continuously provided in the outer peripheral direction in the outer peripheral part of the said metal thin plate in order to improve the processing precision of the said metal thin plate, The any one of Claim 1 thru | or 4 characterized by the above-mentioned. The regenerative heat exchanger according to claim 1.

The regenerative heat exchanger according to any one of claims 1 to 5 , wherein a hollow penetrating in a thickness direction of the metal thin plate is provided in a part of an outer peripheral edge of the metal thin plate .

Regenerative heat exchanger according to any one of claims 1 to 6, characterized by being configured by combining different materials of the metal sheet.