EP0718566A1

EP0718566A1 - Heat exchanger with removable cover and heating apparatus comprising such heat exchanger

Info

Publication number: EP0718566A1
Application number: EP95203447A
Authority: EP
Inventors: Jan Hubertus Deckers
Original assignee: Dejatech Bv
Current assignee: HOLDING J.H. DECKERS N.V.
Priority date: 1994-12-19
Filing date: 1995-12-12
Publication date: 1996-06-26
Also published as: NL9402157A

Abstract

A heat exchanger (1), comprising a burner (5), a flue duct, a heating chamber (2) with heat exchanging elements and a duct for feeding therethrough a medium to be heated, abutting at least partly against the heating chamber (2), wherein the heating chamber (2) is bounded by at least a base plate (3) and a cover (6), with the base plate (3) carrying at least a part of the heat exchanging elements (7) and being in contact with the medium-conveying duct (14), and the cover (6) being simply removable so as to clear at least the heat exchanging elements (7), the arrangement being such that after removal of the cover (6), in particular the base plate (3) and the heat exchanging elements (7) are clear for inspection and maintenance.

Description

This invention relates to a heat exchanger, comprising a burner, a flue duct, a heating chamber with heat exchanging elements and a duct for feeding therethrough a medium to be heated, abutting at least partly against the heating chamber. Such a heat exchanger is known from Dutch patent application 91,02096.
The known heat exchanger consists of a combustion chamber which is bounded on two sides by water ducts for sanitary or space heating water, and at the top by a burner. Extending in the combustion chamber, from both sides, from the water ducts, are finger-shaped projections together defining a labyrinthine passage for flue gases heated by the burner. Connecting adjacent the underside of the combustion chamber is an external flue tube. The projections provide for a good heat exchange between the flue gases and the water being fed through the water ducts.
In the known heat exchanger, the combustion chamber, together with the burner, is composed of two intimately bonded parts, manufactured by casting, each comprising a part of the water duct and a part of the fingers. As a result, the heat exchanger is simple in construction, reliable and has a good efficiency.
During the use of the heat exchanger, by means of the burner heated flue gases are blown between the fingers, whereby heat exchange occurs between the flue gases and the water in the ducts. In particular when the heat exchanger is used at low temperatures, this process will result in relatively much condensate in the combustion chamber. This condensate is to be removed from the combustion chamber and causes undesired fouling in the apparatus. In the known heat exchanger, this means that the combustion chamber must be equipped with condensation discharge means and that, moreover, cleaning the combustion chamber and the burner is difficult to implement.
The object of the invention is to provide a heat exchanger of a type described in the opening paragraph hereof, whereby the disadvantages mentioned are avoided, while the advantages thereof are maintained, and which heat exchanger is suitable over a large temperature range, in particular also at relatively low temperatures. To that end, the heat exchanger according to the invention is characterized by the features according to claim 1.
Because in the heat exchanger according to the invention the cover, which co-defines the heating chamber, is simply removable, the heating chamber, at least the side of the base plate and the heat exchanging elements facing the combustion chamber, and the burner are readily accessible for inspection and maintenance. If during the use of the heat exchanger condensation and/or pollution occurs, the cover can be removed periodically and the different parts can be cleaned. Moreover, when damaged, parts can be simply repaired or replaced. Condensate can be simply collected, for instance in the cover, and be removed after removal of the cover. A further surprising advantage of the heat exchanger according to the invention is that it can be made of relatively shallow design, since a medium-conveying duct is arranged only on one side of the heating chamber. As a result, a compact heat exchanger can be obtained with sufficient capacity and a low convenience time, that is, bringing the water to the desired temperature by means of the heat exchanger takes only little time.
In an advantageous embodiment, the heat exchanger according to the invention is characterized by the features according to claim 2.
In the first (lower) part of a flue duct connecting to a heat exchanger, the flue gases have the highest temperature and moreover most condensate, and hence pollution, will concentrate there. Since in this embodiment of the heat exchanger this first part of the flue duct still extends within the heat exchanger and is covered by the removable cover, the residual heat of the flue gases can still be utilized and this part of the flue duct can moreover be simply inspected and cleaned, while the condensate can be simply removed. In this connection, it is advantageous when the first part of the flue duct is at least partly provided with heat exchanging elements, which preferably allow easier passage to the flue gases than do the heat exchanging elements in the heating chamber. Thus the residual heat of flue gases is utilized in optimum manner.
Further advantageous embodiments of a heat exchanger according to the invention are characterized by the features according to claims 3-7.
The invention further relates to a heating apparatus, comprising a heat exchanger according to the invention, characterized by the features according to claim 8. This heating apparatus has the advantage that it is particularly compact owing to the compact heat exchanger, and moreover has a short convenience time, while yet a relatively large storage vessel for sanitary water or CH water is present. Moreover, this heating apparatus is simple to use and to maintain and relatively inexpensive.
To clarify the invention, an exemplary embodiment of a heat exchanger and a heating apparatus will be described with reference to the drawings.

Fig. 1 shows a front view of a heating apparatus with heat exchanger according to the invention, with the cover removed;
Fig. 2 shows a side view of the heating apparatus with heat exchanger, partly sectioned along the line II-II in Fig. 1, with fitted cover; and
Fig. 3 shows a sectional view taken on the line III-III in Fig. 2 of a heating apparatus according to the invention.

Fig. 1 shows a front view of a heating apparatus with heat exchanger 1 according to the invention, with open heating chamber 2. The heating chamber 2 is bounded at the back by a base plate 3, at the bottom and the two sides by an upright wall 4 and 4' respectively, and at the top by a burner 5. The burner 5 is preferably of the pre-mix type. During normal use, the heating chamber 2 is bounded at the front by a cover 6, removed in Fig. 1, but visible in Fig. 2.
A large number of finger-shaped heat exchanging elements, designated fingers 7, extend from the base plate 3 into the heating chamber 2, as far as a point close to, and preferably substantially against, the cover 6 (when fitted; see Fig. 2). The fingers 7 are, for instance, arranged in rows, such that the fingers 7 in adjacent rows are mutually staggered. Thus the fingers 7 define a labyrinthine path through the heating chamber 2.
Arranged in the heating chamber 2 is a partition 8 which extends in vertical direction from the top, next to the burner 5, in the direction of the bottom wall 4, parallel to the sidewall 4'. The partition 8 terminates at a distance from the bottom wall 4, thereby defining a passage 9. The partition 8, the adjacent sidewall 4', the base plate 3 and the cover 6 define a flue duct 10 which at one end is in open communication with the rest of the heating chamber 2 via the passage 9 and, at the other end, can be joined to a chimney (not shown) via a chimney opening 11. In at least a part of the flue duct 10, as in the rest of the heating chamber 2, fingers 7 can be arranged, preferably at greater intervals.
Extending at the back of the base plate is a water duct 12 having a zigzag course (Fig. 3). This water duct 12 has an inlet side 13 adjacent the underside of the heat exchanger, at the lower end of the flue duct 10, and an outlet side 14 basically located adjacent the top of the heat exchanger 1, diametrically opposite the inlet side 13. A connecting tube 14' extends from the outlet side 14 along the sidewall 4' to a point adjacent the underside of the heat exchanger, such that the heat exchanger, at the underside thereof, is connectable to both the supply and the return pipe of a heating circuit (not shown). Viewed in the direction of flow, the water duct has, for instance, first a vertical loop at the back of the base plate adjacent (a part of) the flue duct 10 and then a number of horizontal loops arranged above each other on the back of the base plate adjacent the rest of the heating chamber 2 (Fig. 3).
The cover 6 is adapted to be clamped against the base plate 3 by means of four clamps 15, the cover 6 engaging the base plate and/or the walls 4, 4' in sealing gastight manner, optionally with interposition of a packing suitable therefor. The clamps 15 are designed as so-called quick acting clamps or comparable clamps. In a first position the cover 6 is pressed down against the base plate 3 by means of the clamps 15, in a second position the cover 6 can be removed. For instance by means of a lever, the clamps are simply movable between the first and the second position. It is noted that all kinds of other relatively simply detachable fastening means can be used, such as clamping springs, (wing) screws, sliding means and the like.
Included on the side of the water duct 12 remote from the base plate 3 is a storage vessel 16 which can contain an amount of water and which, by means of a supply 17 and a discharge 18, is connectable to, for instance, a sanitary water facility or a space heating circuit.
The heat exchanger 1 according to the invention can function as follows, assuming it is included in a suitable heating circuit and connected to a suitable fuel supply.
By means of the burner 5 heated flue gases are forced along the fingers 7 via the labyrinthine path in the direction of the passage 9 and thereafter via the passage 9 and the flue duct 10, along the fingers 7 arranged therein towards the chimney. The flow of the flue gases is indicated schematically by the arrows G. While flowing through the heating chamber 2, including the flue duct 10, the heated flue gases give off their heat substantially to the fingers 7 and the base plate 3. Because the fingers 7, if any, in the flue duct 10 are further spaced apart and occupy only a part of the flue duct, the flue duct ensures an optimal exchange of heat between the relatively cold water and the strongly cooled flue gases. The base plate 3 thereupon gives off the absorbed heat to water which flows through the water duct 12 and can be used, for instance, as sanitary water or for space heating. Moreover, a part of the heat of the flue gases - or all of it, in given cases - can be given off to water in the storage vessel 16.
After a certain lapse of time, the burner 5 can be switched off and the cover be removed upon release of the clamps 15. When the cover 6 has been removed, inter alia the heating chamber 2, the first part of the flue duct 10 and the burner 5 can be inspected and cleaned. Thus, water of condensation, if any, can be removed and so can other kinds of pollution. In addition, the operation of the burner 5 can be checked, for instance by checking the heat exchanger 1 for discolorations, since more strongly heated parts will discolor differently from less heated parts. After inspection and maintenance, the cover 6 can be simply re-placed, whereafter the heating apparatus can directly be set into operation again. The removal of the cover does not require that water be drained or otherwise precautions be taken other than switching off the burner.
In an advantageous embodiment, the base plate 3 is manufactured by die-casting, preferably integrally with the sidewalls 4, 4', the fingers 7, the partition 8, the water duct 12 and/or the burner 5. In addition, the storage vessel 16 may partly or wholly be integrally cast. The cover 6, too, may be manufactured by casting. The parts referred to are preferably manufactured from aluminium or an aluminium alloy or like light metal. These have a favourable weight and favourable manufacturing and heat-technical characteristics.
By way of illustration, a number of dimensions of possible embodiments of a heating apparatus are given, which are not to be construed as limitative. The heat exchanger has, for instance, a width of between 200 and 450 mm and a height of between 300 and 600 mm. The depth of the heating chamber is, for instance, approximately 55 mm, the maximum depth of the cover approximately 100 mm, adjacent the connection for the chimney. The flue duct extends into the heating chamber over a length of, for instance, approximately 500 mm. Given the conventionally adopted depth gauge for a heating apparatus for CH and/or sanitary water heating of 400 mm, then a storage vessel of approximately 50 liters can be incorporated. The heating apparatus according to the invention is suitable in particular for use in low-temperature heating circuits, for instance at water temperatures of less than 50°C, such as floor heating.
The invention is not limited in any way to the embodiments represented in the specification and drawings. For instance, different heat exchanging elements can be used and different arrangements thereof. Moreover, they can be omitted in the flue duct. Also, the flue duct may extend entirely outside the heating chamber or be incorporated therein for a larger part, for instance by arranging one or more further partitions. The cover may be designed differently, optionally in several parts, and may render the heating chamber accessible from a different side. The cover can be secured with a different number of clamps and can otherwise be detachably mounted in any suitable manner. Further, the water duct may be designed differently, for instance traverse a different course, or be arranged at least partly on other sides of the heat exchanger, and the storage vessel can be omitted or be in direct contact with the base plate. Although the heating apparatus is suitable in particular for use at low temperatures, the use thereof is naturally not limited thereto. These and many other modifications are understood to fall within the scope of the invention.

Claims

A heat exchanger, comprising a burner, a flue duct, a heating chamber with heat exchanging elements and a duct for feeding therethrough a medium to be heated, abutting at least partly against the heating chamber, characterized in that the heating chamber is bounded by at least a base plate and a cover, with the base plate carrying at least a part of the heat exchanging elements and being in contact with the medium-conveying duct, and the cover being simply removable so as to clear at least the heat exchanging elements, the arrangement being such that after removal of the cover, in particular the base plate and the heat exchanging elements are clear for inspection and maintenance.
A heat exchanger according to claim 1, characterized in that at least a part of the flue duct extends through the heating chamber, which part is covered and clearable by the removable cover.
A heat exchanger according to claim 1 or 2, characterized in that the base plate, at least during normal use, includes an angle with the horizontal and extends preferably in substantially vertical direction, with the burner connecting to the heating chamber adjacent the upper end of the base plate, and the flue duct connecting thereto adjacent the lower end of the base plate.
A heat exchanger according to any one of the preceding claims, characterized in that substantially all heat exchanging elements extend from the base plate into the heating chamber as far as close to the cover.
A heat exchanger according to any one of the preceding claims, characterized in that the base plate and the cover are manufactured from aluminium or an aluminium alloy, preferably by casting, with the heat exchanging elements being formed integrally with the base plate.
A heat exchanger according to any one of the preceding claims, characterized in that clamping means are provided for clamping the cover against the base plate.
A heat exchanger according to any one of the preceding claims, characterized in that a part of the heat exchanging elements extend in the flue duct.
A heating apparatus comprising a heat exchanger according to any one of the preceding claims, characterized in that it comprises on the side of the medium-conveying duct remote from the base plate a storage vessel in which water heated by the heat exchanger can be collected, the storage vessel and/or the medium-conveying duct being incorporable in a sanitary water circuit and/or a space heating circuit.