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Dokumentenidentifikation EP1588042 21.09.2006
EP-Veröffentlichungsnummer 0001588042
Titel STIRLING-MOTORANORDNUNG
Anmelder Microgen Energy Ltd., Reading, Berkshire, GB
Erfinder CLARK, Anthony, David, Leicestershire LE67 2BU, GB;
COOPER, Edward, James, Leicestershire LE11 2RD, GB;
HASKO, Michael, Stephen, Huntingdon, GB;
SPENCELEY, John, Christopher, Berkshire RG18 0UT, GB
Vertreter derzeit kein Vertreter bestellt
DE-Aktenzeichen 602004001858
Vertragsstaaten AT, BE, BG, CH, CY, CZ, DE, DK, EE, ES, FI, FR, GB, GR, HU, IE, IT, LI, LU, MC, NL, PT, RO, SE, SI, SK, TR
Sprache des Dokument EN
EP-Anmeldetag 23.01.2004
EP-Aktenzeichen 047046511
WO-Anmeldetag 23.01.2004
PCT-Aktenzeichen PCT/GB2004/000299
WO-Veröffentlichungsnummer 2004065778
WO-Veröffentlichungsdatum 05.08.2004
EP-Offenlegungsdatum 26.10.2005
EP date of grant 09.08.2006
Veröffentlichungstag im Patentblatt 21.09.2006
IPC-Hauptklasse F02G 1/055(2006.01)A, F, I, 20051017, B, H, EP
IPC-Nebenklasse F02G 1/043(2006.01)A, L, I, 20051017, B, H, EP   

Beschreibung[en]

The present invention relates to a Stirling engine assembly.

Stirling engine assemblies are known in the art, for example, WO 99/40309 and WO 02/070887 having a recuperator at the Stirling engine head to heat the air supplied to the burner with combustion gases from the burner. The exterior surface of the recuperator is exposed to the air within the interior of an appliance and hence any heat dissipated from the surface of the recuperator is dissipated into the appliance.

The principal purpose of the burner/recuperator assembly is to maintain the temperature of the engine head with the minimum amount of energy. This minimisation of energy is achieved with the use of the recuperator which recovers heat from the burner exhaust gas and uses it to preheat air/gas mixture supplied to the burner. The degree of recuperation and thermal efficiency can be maintained with the use of insulation around the outside of the appliance. However, two factors must be taken into consideration.

Firstly, the temperature of the incoming air/gas mixture must remain below a critical upper limit. If this limit is exceeded, auto-ignition of the mixture can occur resulting in further over heating and potential damage to the appliance.

Secondly, the appliance may house thermally sensitive electrical components which have a nominal maximum temperature. Therefore, the amount of heat dissipated from the burner/recuperator assembly must be maintained at a level to prevent any damage to the electrical components.

According to the present invention the Stirling engine assembly comprises a Stirling engine having a head; a burner surrounding the head and comprising a burner element on which a flame is sustained, the burner being fed with a combustible gas stream; and a recuperator to preheat the gas stream with combustion products from the burner; characterised by a coolant circuit positioned to absorb heat, which is radiated from the back of the burner element away from the head, into a coolant stream separate from the gas stream.

The present invention uses a burner which surrounds the Stirling engine head to provide particularly effective heat transfer to the head. However, a significant amount of heat radiates away from the burner element which, in turn, can radiate to the recuperator walls and subsequently into the appliance. By removing some of this heat into a separate coolant stream, the temperature of both the incoming gas and the interior of the appliance can be controlled.

The coolant stream for the burner element may be a dedicated stream. However, preferably, the coolant stream is a stream which has cooled the cool end of the Stirling engine. Such a stream is conveniently available and therefore has cost and space benefits.

Preferably, the coolant stream is arranged to subsequently receive heat from the exhaust gas from the burner. In domestic combined heat and power applications, the coolant stream which is heated in this way can be used to supply a domestic heating requirement such as the central heating or water heating. With such an arrangement, a supplementary burner is preferably also provided to supply further heat to the coolant stream to ensure that the domestic heat demand can be met at all times.

A flexible seal may be provided between the burner and the Stirling engine head in order to prevent the escape of gases from the burner into the appliance. In this case, the seal may also be cooled by the coolant stream which is used to cool the burner element. The cooled flexible seal arrangement is the subject of a separate co-pending application GB 0211121.9. The burner element and seal may be positioned such that a common duct for the coolant stream can cool both the burner element and seal on a single pass around the head.

An example of a burner assembly in accordance with the present invention will now be described with reference to the accompanying drawings, in which:

  • Fig. 1 is a schematic representation of a combined heat and power system incorporating a Stirling engine assembly of the present invention;
  • Fig. 2 is a cross-section through a Stirling engine assembly of the present invention; and
  • Fig. 3 shows, in cross-section, part of a Stirling engine assembly according to the present invention with a modified cooling arrangement.

The domestic combined heat and power system shown in Fig. 1 comprises a Stirling engine assembly 1 together with a supplementary burner 2 and a heat exchanger 3 in which water from a domestic central heating or hot water system is heated by exhaust gas from the Stirling engine assembly and by the supplementary burner.

The Stirling engine assembly 1 comprises a Stirling engine 4 supported on a resilient support 5. A fan 6 provides a supply of combustible gas to a burner 7 surrounding the head 8 of the Stirling engine. The gas is supplied along the gas supply duct 9 and combustion gases which have heated the head 8 subsequently flow along exhaust gas duct 10 which is surrounded by the gas supply duct 9. Exhaust gas is subsequently fed to the heat exchanger 3 where it combines with combustion products from the supplementary burner 2 (which is also fed with combustible gases by fan 6). The combined stream is then exhausted through a concentric flue 11.

The nature of the Stirling engine assembly is shown in more detail in Fig. 2.

In addition to the engine head 8, the Stirling engine comprises an engine cooler 12 and an alternator 13. The internal structure of a Stirling engine is well known in the art and will not be described in greater detail here. An annular absorber mass 14 surrounds the Stirling engine 4 and is resiliently mounted thereto to counteract vibrations of the Stirling engine.

A recuperator 20 is positioned above and around the head 8 of the Stirling engine. The recuperator comprises an outer casing 21 in which a block of insulation 22 is mounted. The gas supply duct 9 is defined between the casing 21 and insulation 22, while the bottom surface of the block of insulation 22 is profiled to define the exhaust gas duct 10 between itself and the Stirling engine head 8. This extends out through top of the casing 21 as shown at 10' in Fig. 2, although this duct is out of the plane of the cross-section of Fig. 2.

The burner 7 has a flame distribution strip 23 which distributes the gas more evenly to the annular burner 7. The majority of the heat from the burner 7 is transmitted by forced convection and radiation to the heater head 8, with the absorption being aided by a system of annular fins 24. Some heat is radiated into the recuperator or radially outwardly of the burner as described in greater detail below.

The Stirling engine 4 will vibrate to a limited degree with respect to the burner 7 and recuperator 20. A flexible seal 25 is therefore provided between the Stirling engine 4 and the burner housing. As shown in Fig. 2, this seal is positioned away from the burner 7 and separated from the burner by a block of insulation 26 in order to limit the temperature that the seal 25 has to withstand.

The cooling arrangement for the Stirling engine is as follows. Cool water which, in a domestic combined heat and power system, has given up its heat to satisfy the domestic heat requirement is initially passed around engine cooler 30 to maintain the cold end 12 of the Stirling engine at the lowest possible temperature. The water is then fed around a seal cooler path 31 surrounding the insulation 26 to absorb heat at this point thereby limiting further the temperature that the seal 25 has to withstand.

The water is then fed to an annular burner cooler path 32 surrounding the burner 7 which absorbs the heat which is radiated outwardly from the flame distribution strip 23. As shown in Fig. 1, the water is then fed to heat exchanger 3 where it is further heated by the exhaust gas from the Stirling engine and by the supplementary burner 2 as described above.

Although the various water paths have been described above as being in series, it is possible for certain of the paths to be arranged in parallel. In particular, the seal cooler path 31 and burner cooler path 32 may be in parallel, with manually adjusted flow control valves located in the parallel flow paths, to enable the flows to be balanced.

As the burner cooler path 32 extracts heat from the burner, the effect of using this is that, in order to maintain the nominal head operating temperature of approximately 550□C, more heat is required from the burner. However, this is offset by an increase in thermal efficiency due to the recovery of heat from the burner that would otherwise have been dissipated into the appliance.

An alternative configuration for cooling the recuperator is shown in Fig. 3. This figure shows only a top left hand portion of the Stirling engine assembly as the remainder of the engine is as shown in Fig. 2.

In the example of Fig. 3, the seal cooler path 31 and burner cooler path 32 have been replaced by a single cooling channel 40. A thermal bridge 41, which is an annular disk of material of high thermal conductivity, provides a heat path from the burner 7 to the cooling channel 40, while the seal 25 is positioned adjacent to the cooling channel 40. This allows the integration of the cooling arrangement for the burner 7 and seal 25 into a single assembly thereby reducing manufacturing costs and materials.


Anspruch[de]
Stirlingmotor-Anordnung, umfassend einen Stirlingmotor (4) mit einem Kopf (8), einen den Kopf umgebenden Brenner (7), welcher ein Brennerelement umfasst, an dem eine Flamme aufrechterhalten wird, wobei dem Brenner ein brennbarer Gasstrom zugeführt wird; und einen Rekuperator (20) zum Vorheizen des Gasstroms mit Verbrennungsprodukten des Brenners; gekennzeichnet durch einen Kühlmittelkreislauf (32), der dazu positioniert ist, Hitze, welche von der Rückseite des Brennerelements von dem Kopf weg abgestrahlt wird, in einen Kühlmittelstrom, getrennt von dem Gasstrom, aufzunehmen. Anordnung nach Anspruch 1, wobei der Kühlmittelstrom (30) dazu konfiguriert ist, vor dem Herumfließen um das Brennerelement um ein Kühlende (12) des Sterlingmotors herum zu fließen. Anordnung nach Anspruch 1, wobei der Kühlmittelstrom dazu konfiguriert ist, Hitze von dem Abgas des Brenners (7) aufzunehmen, nachdem er um das Brennerelement herum geflossen ist. Anordnung nach Anspruch 3, wobei der Kühlmittelstrom dazu konfiguriert ist, Hitze von einem zusätzlichen Brenner (2) aufzunehmen, nachdem er um das Brennerelement herum geflossen ist. Anordnung nach einem der vorangehenden Ansprüche, wobei eine flexible Dichtung (25) zwischen dem Brenner (7) und dem Sterlingmotorkopf (8) dazu vorgesehen ist, das Entweichen von Gasen aus dem Brenner zu verhindem, und wobei der Kühlmittelstrom dazu konfiguriert ist, die flexible Dichtung zu kühlen. Vorrichtung nach Anspruch 5, wobei der Kühlmittelstrom derart konfiguriert ist, dass eine gemeinsame Leitung (40) sowohl das Brennerelement (1) als auch die Dichtung (25) in einem einzigen Umlauf um den Kopf herum kühlt.
Anspruch[en]
A Stirling engine assembly comprising a Stirling engine (4) having a head (8) a burner (7) surrounding the head and comprising a burner element on which a flame is sustained, the burner being fed with a combustible gas stream; and a recuperator (20) to preheat the gas stream with combustion products from the burner; characterised by a coolant circuit (32) positioned to absorb heat, which is radiated from the back of the burner element away from the head, into a coolant stream separate from the gas stream. An assembly according to claim i, wherein the coolant stream is configured to pass around a cool end (12) of the Stirling engine prior to passing around the burner element. An assembly according to claim 1, wherein the coolant stream is configured to receive heat from the exhaust gas from the burner (7) cafter it has passed around the burner element. An assembly according to claim 3, wherein the coolant stream is configured to receive heat from a supplementary burner (2) after it has passed around the burner element. An assembly according to any one of the preceding claims, wherein a flexible seal (25) is provided between the burner (7) and the Stirling engine head (8) in order to prevent the escape of gases from the burner, and the coolant stream is configured to cool the flexible seal. An assembly according to claim 5, wherein the coolant stream is configured such that a common duct (40) cools both the burner element (7) and seal (25) on a single pass around the head.
Anspruch[fr]
Ensemble de moteur Stirling comprenant un moteur Stirling (4) comportant une tête (8), un brûleur (7) entourant la tête et comprenant un élément de brûleur sur lequel une flamme est entretenue, le brûleur étant alimenté par un flux de gaz combustible ; et un récupérateur (20) destiné à préchauffer le flux de gaz à l'aide de produits de combustion provenant du brûleur ; caractérisé par un circuit (32) de refroidissement positionné pour absorber de la chaleur, qui rayonne depuis l'arrière de l'élément de brûleur en s'écartant de la tête, dans un flux d'agent de refroidissement séparé du flux de gaz. Ensemble selon la revendication 1, dans lequel le flux d'agent de refroidissement est configuré pour passer autour d'une extrémité froide (12) du moteur Stirling avant de passer autour de l'élément de brûleur. Ensemble selon la revendication 1, dans lequel le flux d'agent de refroidissement est configuré pour recevoir de la chaleur du gaz d'échappement provenant du brûleur (7) après son passage autour de l'élément de brûleur. Ensemble selon la revendication 3, dans lequel le flux d'agent de refroidissement est configuré pour recevoir de la chaleur provenant d'un brûleur supplémentaire (2) après son passage autour de l'élément de brûleur. Ensemble selon l'une quelconque des revendications précédentes, dans lequel un joint d'étanchéité souple (25) est disposé entre le brûleur (7) et la tête (8) de moteur Stirling afin d'empêcher que le gaz ne s'échappe du brûleur, et le flux d'agent de refroidissement est configuré pour refroidir le joint d'étanchéité souple. Ensemble selon la revendication 5, dans lequel le flux d'agent de refroidissement est configuré de sorte qu'un conduit commun (40) refroidit à la fois l'élément (7) de brûleur et le joint d'étanchéité (25) en un seul passage autour de la tête.






IPC
A Täglicher Lebensbedarf
B Arbeitsverfahren; Transportieren
C Chemie; Hüttenwesen
D Textilien; Papier
E Bauwesen; Erdbohren; Bergbau
F Maschinenbau; Beleuchtung; Heizung; Waffen; Sprengen
G Physik
H Elektrotechnik

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