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(11) | EP 0 889 292 B1 |
| (12) | EUROPEAN PATENT SPECIFICATION |
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| (54) |
Heat exchanger and central heating boiler comprising such heat exchanger Wärmetauscher und Zentralheizungskessel mit so einem Wärmetauscher Echangeur de chaleur et chaudière pour chauffage central avec un tel échangeur de chaleur |
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| Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). |
[0001] The invention relates to a heat exchanger intended for a central heating boiler, which heat exchanger is manufactured as a monocasting from substantially aluminum, the heat exchanger comprising a number of walls which bound on one side a water-carrying channel and on the other a burner space.
[0002] A central heating boiler comprising such heat exchanger is known from practice and is for instance marketed by applicant under the type indications W21c ECO and W28c ECO. The principle of the W21c ECO is shown in a brochure of applicant dated February 1996. The maximal output of the known boiler is 21 kW and 28 kW respectively. A particular advantage of the known boiler is that it is particularly compact. The built-in depth of the known boiler is for instance 350 mm. Another advantage of the heat exchanger of the known boiler is that it is designed as a monoblock casting, as a result of which the manufacture thereof is relatively simple.
[0003] The output of a central heating boiler is inter alia determined by the size of the burner that is used. In the known boiler, the burner, which is substantially of cylindrical design, is cantilevered at one end face thereof. When a greater output is required, the length of the burner could be increased. However, this leads to problems with regard to the one-sided suspension of the burner. Moreover, as a consequence hereof, the built-in depth of the central heating boiler becomes too great.
[0004] Another possibility for increasing the output of the known boiler is enlarging the diameter of the burner. Although this is in itself possible, the amount of flue gas to be discharged will then form a problem. The known boiler comprises a single flue gas draft. In this single flue gas draft the temperature of the flue gases must be reduced as far as possible, so that as much heat as possible is transferred from the flue gases to the water to be heated. In order to arrive at a proper heat transfer, pins increasing the heat-transferring surface extend in the flue gas draft. To enable the larger amount of flue gas to be discharged, the section of the flue gas draft would have to be enlarged. This means that for a proper heat transfer to be maintained, the pins increasing the heat-transferring surface would have to be of a longer design. However, this is not possible, because during the casting of the heat exchanger, the molten aluminum flowing into the cavities for forming the pins has already solidified before the end of the cavity is reached. Consequently, the further elongation of the pins is not possible due to problems in terms of casting technique. Due to the above-described problems, it is not possible to merely increase the diameter of the burner for increasing the output of the central heating boiler.
[0005] The object of the invention is to provide a heat exchanger intended for a central heating boiler having a greater output than the known central heating boiler, the intended heat exchanger being particularly compact and hence suitable for a central heating boiler which, like the known boiler, has a slight built-in depth.
[0006] To this end the heat exchanger according to the invention is manufactured as a monocasting from substantially aluminum, the heat exchanger comprising the features of claim 1.
[0007] The heat exchanger being manufactured as a monocasting, it can be manufactured in a relatively quick and efficient manner. The presence of more than one flue gas draft enables discharging a greater amount of flue gas, while the section of the flue gas drafts can remain small, so that relative to the flow-through section, a relatively large heat-transferring surface is nevertheless obtained. Due to the greater amount of flue gas that can be discharged, a larger burner having a greater output can be used. Outputs up to about 30 kW per flue gas draft are possible in the heat exchanger according to the invention. Because the heat exchanger according to the invention now involves parallel flue gas drafts, preferably located side by side, the slight built-in depth of the known central heating boiler can be maintained. Hence, with the heat exchanger according to the invention, a central heating boiler can be provided having a greater output than the known central heating boiler while the same degree of compactness is achieved, in particular with regard to the built-in depth. As the walls which bound the burner space and the flue gas drafts are water-cooled, an optimal heat-transfer to the water to be heated is obtained, while, moreover, the heat exchanger is cooled in an efficient manner, so that it nowhere becomes overheated. The one-piece core renders the manufacture of the core and the positioning of the core in the mold relatively simple, so that the manufacture of the heat exchanger is relatively simple as well and, accordingly, can take place in an economically favorable manner.
[0008] According to a further elaboration of the invention, intended for increasing the efficiency of a central heating boiler, comprising a heat exchanger according to the invention, each flue gas draft of the heat exchanger may comprise two opposite walls having pins extending substantially perpendicularly thereto, which pins enlarge the heat-transferring surface and extend into the relevant flue gas draft.
[0009] The invention also relates to a central heating boiler comprising a heat exchanger according to the invention. It is a matter of course that such central heating boiler has the advantages mentioned hereinabove in respect of the heat exchanger.
[0010] It should be noted that DE-A-34 27 957 discloses a central heating boiler comprising a heat exchanger, which heat exchanger seems to be designed as two castings which are manufactured separately and subsequently connected to each other. The known heat exchanger comprises a single flue gas draft. The problems of such a single flue gas draft are described above in relation to the W21c ECO and W28 c ECO devices. The walls of the known heat exchanger bound on one side a water-carrying channel and on the other a burner space and the said single flue gas draft.
[0011] Further elaborations of the invention are described in the subclaims and will hereinafter be specified on the basis of an exemplary embodiment, with reference to the accompanying drawings.
Fig. 1 is a perspective view of an exemplary embodiment of a heat exchanger according to the invention;
Fig. 2 is a sectional view taken on the plane II-II of Fig. 1; and
Fig. 3 is a perspective view of the principle of the water-side core intended for forming the water-carrying channel of the heat exchanger according to the invention.
[0012] Fig. 1 shows an exemplary embodiment of the heat exchanger 1 according to the invention. As is clearly visible, the heat exchanger 1 is manufactured as a monocasting substantially from aluminum. The heat exchanger comprises a number of walls 2, 3, 4, which walls bound on one side a water-carrying channel 5 and on the other a burner space 6 and two parallel flue gas drafts 7, 8. The flue gas drafts 7, 8 extend from the burner space 6. The burner space 6 is intended for accommodating a burner. The walls 2, 3, 4 bounding the burner space 6 and the flue gas drafts 7, 8 are water-cooled in that the water-carrying channel 5 extends therealong. The water-carrying channel 5 is of such design that it is formed with a single, one-piece core 9, shown in Fig. 3. Each flue gas draft 7, 8 comprises two opposite walls 2, 3 having pins 10 extending substantially perpendicularly thereto, which pins enlarge the heat-exchanging surface and extend into the relevant flue gas draft 7, 8. The flow system of the water-carrying channel can be considered to be a series connection of a number of parallel channel parts. In explanation thereof, I refer to Fig. 3, which, it is true, shows the core by means of which the water-carrying channel is formed, but which can also be considered to be a representation of the water-carrying channel itself. Water coming from a central heating pipe system enters the heat exchanger adjacent its bottom side at the location of arrow R. From there, it continues its path in a feed-in part 5a of the water-carrying channel 5. Adjacent the rear of the heat exchanger 1, the channel 5a divides into two separate channel parts 5b, 5c. Such division is clearly shown in Fig. 2. Located in channel 5b is a partition 11 which forces the hot water to flow forwards again to subsequently rise again and flow back towards the rear again. From the rear, the water then flows in a common channel part 5d which separates the two flue gas drafts 7, 8 from each other. In the channel 5d, too, a partition 12 is located, which provides that the water first flows forwards and then upwards, to subsequently flow to the rear again, enabling the water to divide again from there and flow to two following separate subchannels 5b' and 5c'. This process repeats itself again, after which the water flows, via 5b''' and 5c''', into a common channel 5E, whence the water flows to the inlet A of the central heating pipe system. With such embodiment of the water-carrying channel 5, it is effected that all walls of the flue gas drafts and the burner space are water-cooled, so that an optimal efficiency is obtained and all parts of the heat exchanger remain sufficiently cooled. To effect an easy cleaning of the flue gas drafts and a proper accessibility of the burner space 6, this burner space 6 and the flue gas drafts 7, 8 are accessible from at least one side S. The side S is clearly indicated in Fig. 2. Fig. 2 also clearly shows that the water-carrying channel 5 has a substantially m-shaped section, viewed in a direction perpendicular to a horizontal cross-sectional plane II-II located at the level of the flue gas drafts 7, 8.
1. A heat exchanger intended for a central heating boiler, said heat exchanger (1) being
manufactured as a monocasting from substantially aluminum, the heat exchanger comprising
a number of walls (2, 3, 4), said walls bounding on one side a water-carrying channel
(5) and on the other side a burner space (6), characterized in that the heat exchanger comprises at least two parallel flue gas drafts (7, 8), extending
from the burner space (6), the burner space (6) being intended for accommodating a
burner, and the walls (2, 3, 4) which bound the burner space (6) and the flue gas
drafts (7, 8) being water-cooled in that the water-carrying channel (5) extends therealong, and the water-carrying channel
(5) being formed from a single, one-piece core (9).
2. A heat exchanger according to claim 1, characterized in that each flue gas draft (7, 8) comprises two opposite walls (2, 3) having pins (10) extending
substantially perpendicularly thereto, which pins enlarge the heat-exchanging surface
and extend into the relevant flue gas draft (7, 8).
3. A heat exchanger according to claim 1 or 2, characterized in that the flow system of the water-carrying channel (5) is a series connection of a number
of parallel channel parts.
4. A heat exchanger according to claim 3, characterized in that the water-carrying channel (5) comprises a single feed-in part (5a) dividing into
two first, separate channel parts (5b, 5c), said first separate channel parts (5b,
5c) meeting in a first common channel part (5d), said first common channel part (5d)
dividing into two following separate channel parts (5b', 5c'), said following channel
parts (5b', 5c') meeting in a following common channel part (5d'), the pattern of
a common channel part (5d) and two separate channel parts (5b, 5c) connecting thereto
repeating itself a number of times, a final common channel part (5e) terminating in
a discharge opening.
5. A heat exchanger according to claim 4, characterized in that the heat exchanger (1) comprises two parallel flue gas drafts (7, 8), separated from
each other by two walls (3) which also bound the common channel parts (5d, 5d'), except
for the final common channel part.
6. A heat exchanger according to any one of the preceding claims, characterized in that the burner space (6) and the flue gas drafts (7, 8) are accessible from at least
one side (S).
7. A heat exchanger according to claims 5 and 6, characterized in that the water-carrying channel (5) has a substantially m-shaped section, viewed in a
direction perpendicular to a horizontal cross-sectional plane (II-II) located at the
level of the flue gas drafts (7, 8).
8. A central heating boiler comprising a heat exchanger (1) according to any one of claims
1-7.
1. Wärmetauscher für einen Zentralheizungskessel, wobei der Wärmetauscher (1) als einteiliges
Gußteil aus im wesentlichen Aluminium hergestellt ist und eine Anzahl von Wänden (2,
3, 4,) aufweist, die auf der einen Seite einen wasserführenden Kanal (5) und auf der
anderen Seite einen Brennerraum (6) begrenzen, dadurch gekennzeichnet, daß der Wärmetauscher wenigstens zwei parallele Abgaszüge (7, 8) aufweist, die sich vom
Brennerraum (6) aus erstrecken, wobei der Brennerraum (6) zum Aufnehmen eines Brenners
vorgesehen ist, und die Wände (2, 3, 4), welche den Brennerraum (6) und die Abgaszüge
(7, 8) begrenzen, dadurch wassergekühlt sind, daß sich der wasserführende Kanal (5)
entlang derselben erstreckt, und der wasserführende Kanal (5) aus einem einzelnen
einteiligen Kern (9) gebildet ist.
2. Wärmetauscher nach Anspruch 1, dadurch gekennzeichnet, daß jeder Abgaszug (7, 8) zwei gegenüberliegende Wände (2, 3) aufweist, die sich im wesentlichen
senkrecht zu diesen erstreckende Stifte (10) aufweisen, welche die Wärmeaustauschoberfläche
vergrößern und sich in den betreffenden Abgaszug (7, 8) erstrecken.
3. Wärmetauscher nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß das Strömungssystem des wasserführenden Kanals (5) eine Reihenschaltung mehrerer
paralleler Kanalteile ist.
4. Wärmetauscher nach Anspruch 3, dadurch gekennzeichnet, daß der wasserführende Kanal (5) einen einzelnen Einlaßteil (5a) aufweist, der sich in
zwei erste, separate Kanalteile (5b, 5c) teilt, wobei sich die ersten, separaten Kanalteile
(5b, 5c) in einem ersten, gemeinsamen Kanalteil (5d) treffen, wobei sich der erste,
gemeinsame Kanalteil (5d) in zwei nachfolgende zweite separate Kanalteile (5b', 5c')
teilt, wobei sich die nachfolgenden zweiten separaten Kanalteile (5b', 5c') in einem
nachfolgenden gemeinsamen Kanalteil (d') treffen, wobei sich das Muster des gemeinsamen
Kanalteils (5d) und der daran anschließenden zwei separaten Kanalteile (5b, 5c) sich
mehrmals wiederholt, wobei ein letzter gemeinsamer Kanalteil (5e) in einer Auslaßöffnung
endet.
5. Wärmetauscher nach Anspruch 4, dadurch gekennzeichnet, daß der Wärmetauscher (1) zwei parallele Abgaszüge (7, 8) aufweist, die voneinander durch
zwei Wände (3) getrennt sind, welche ferner die gemeinsamen Kanalteile (5d, 5d') mit
Ausnahme des letzten gemeinsamen Kanalteils begrenzen.
6. Wärmetauscher nach einem de vorhergehenden Ansprüche, dadurch gekennzeichnet, daß der Brennerraum (6) und die Abgaszüge (7, 8) von wenigstens einer Seite (S) her zugängig
sind.
7. Wärmetauscher nach Anspruch 5 und 6, dadurch gekennzeichnet, daß der wasserführende Kanal (5), senkrecht zu einer auf der Höhe der Abgaszüge (7, 8)
angeordneten horizontalen Querschnittsebene (II-II) gesehen, einen im wesentlichen
m-förmigen Querschnitt hat.
8. Zentralheizungskessel mit einem Wärmetauscher (1) nach einem der Ansprüche 1-7.
1. Echangeur de chaleur destiné à une chaudière de chauffage central, l'échangeur de
chaleur (1) étant réalisé par moulage monobloc d'aluminium pratiquement, l'échangeur
de chaleur comprenant un certain nombre de parois (2, 3, 4), les parois délimitant
d'un premier côté un canal (5) de transmission d'eau et de l'autre côté un espace
(6) de brûleur, caractérisé en ce que l'échangeur de chaleur comprend au moins deux cheminées parallèles (7, 8) qui s'étendent
depuis l'espace (6) de brûleur, l'espace (6) de brûleur étant destiné à loger un brûleur,
et les parois (2, 3, 4) qui délimitent l'espace (6) de brûleur et les cheminées (7,
8) de gaz brûlés étant refroidies par de l'eau car le canal (5) de transmission d'eau
s'étend sur leur longueur, et le canal de transmission d'eau (5) est formé à partir
d'un noyau unique en une seule pièce (9).
2. Echangeur de chaleur selon la revendication 1, caractérisé en ce que chaque cheminée (7, 8) de gaz brûlés comporte deux parois opposées (2, 3) ayant des
broches (10) qui s'étendent en direction pratiquement perpendiculaire, ces broches
augmentant la surface d'échange de chaleur et s'étendant dans la cheminée correspondante
(7, 8) de gaz brûlés.
3. Echangeur de chaleur selon la revendication 1 ou 2, caractérisé en ce que le système de circulation du canal (5) de transmission d'eau est raccordé en série
avec un certain nombre de parties parallèles de canal.
4. Echangeur de chaleur selon la revendication 3, caractérisé en ce que le canal de transmission d'eau (5) comporte une seule partie d'alimentation (5a)
qui se divise en deux premières parties séparées de canal (5b, 5c), les premières
parties séparées de canal (5b, 5c) se rejoignant dans une première partie commune
de canal (5d), la première partie commune de canal (5d) se divisant en deux parties
séparées suivantes de canal (5b', 5c'), les parties suivantes de canal (5b', 5c')
se rejoignant dama une partie commune suivante de canal (5d'), le motif d'une partie
commune de canal (5d) et de deux parties séparées de canal (5b, 5c) qui se raccordent
se répétant de lui-même un certain nombre de foie, une partie commune finale de canal
(5e) aboutissant à une ouverture d'évacuation.
5. Echangeur de chaleur selon la revendication 4, caractérisé en ce que l'échangeur de chaleur (1) comporte deux cheminées parallèles (7, 8) de gaz brûlés,
séparées l'une de l'autre par deux parois (3) qui délimitent aussi les parties communes
de canal (5d, 5d'), sauf la partie commune finale de canal.
6. Echangeur de chaleur selon l'une quedconque des revendications précédentes, caractérisé en ce que l'espace (6) de brûleur et les cheminées (7, 8) de gaz brûlés sont accessibles depuis
un côté au moins (S).
7. Echangeur de chaleur selon les revendications 5 et 6, caractérisé en ce que le canal de transmission d'eau (5) a une section pratiquement en m, en direction
perpendiculaire à un plan horizontal de coupe (II-II) qui se trouve, au niveau des
cheminées (7, 8) de gas brûlés.
8. Chaudière de chauffage central comprenant un échangeur de chaleur (1) selon l'une
quelconque des revendications 1 à 7.