EP0093141B1

EP0093141B1 - Heat exchanger of convector type

Info

Publication number: EP0093141B1
Application number: EP82903348A
Authority: EP
Inventors: Jan Hiselius
Original assignee: Nya Enacon Energi AB
Current assignee: Nya Enacon Energi AB
Priority date: 1981-10-30
Filing date: 1982-10-29
Publication date: 1985-10-09
Also published as: ATE16046T1; JPS58501837A; SE8106427L; EP0093141A1; WO1983001678A1; DE3266862D1

Abstract

A space heater of convector type comprises at least one disc package and a tube system, which carries the disc package and through which hot water is arranged to flow, each disc package having a plurality of vertical convection channels for heated air. A convector cover (1) forms a continuous unit and surrounds and essentially conceals the tube system (3) and the disc package (2) carried thereby. The tube system (3) is loosely suspended in the cover (1) in a manner such that thermal stress caused by temperature variations in the tube system and the disc package is not transferred to the cover, and that the disc package or packages (2) are spaced apart from the cover (1).

Description

The present invention relates to a space heater of convector type, i.e. a space heater wherein the heating to the major part takes place by convection, this in contrast to traditional radiation heaters, wherein the heating mainly takes place by radiation.
Convection heaters have many advantages compared to radiation heaters, and various types of convection heaters have been developed. However, these known convection heaters have several drawbacks, and the invention aims at eliminating or reducing the drawbacks of known convection heaters.
The known convection heaters, which are closest to the invention, are based on a so-called disc package essentially consisting of a number of tubes, wherein the heating water flows, and a series of adjacent discs which are attached to the tubes in heat transfering contact with the same and form vertical convection channels between adjacent discs. In one known such convection heater, which is available on the market, the very disc package serves as the cover of the convector. Therefore, the disc package has to be optimized with regard to mechanical strength. As examples of drawbacks of this construction can be mentioned that it is expensive per unit of power and complex to produce, not the least since one has to- avoid, to the greatest possible extent, heat distortion of the disc package, which as mentioned forms the very "cover" and accordingly should have an aesthetically attractive appearance.
In another known, commercially available convection heater of the indicated type a wall bracket is used, and the disc package is attached directly to this bracket, a loose front also being used for hiding the disc package. Apart from requiring many separate parts to be screwed together, this construction also has the drawback of having a large volume per unit of power.
DE-A-2509191 discloses a heater/cooler which basically is a heat radiator rather than a heat convector, and wherein the heat exchanger unit is in contact with the cover and with firm attachment to the cover such as by welding.
A major problem of the prior art space heaters of the convector type, comprising a convection heating unit (disc package) and a cover for the same, is that there is no distinct separation between the heating and covering functions. This i.a. means that it has been necessary to consider not only the heating aspects, but also the visual or aesthetical aspects when designing the heating .unit. In particular, it has not been possible to maximize the heating properties of the prior art heaters due to transfer of thermal stress from the heating unit to the cover.
The present invention solves these and related problems by providing a convector cover, which forms a continuous unit surrounding and essentially concealing the heating unit, the latter being loosely suspended in the cover with the disc package or packages being spaced apart from the cover, so that the thermal stress caused by temperature variations in the heating unit is not transfered to the cover.
Secondary objects of the invention are i.a. to provide a convection heater having high heating effect per unit of volume, resulting in a small overall size, which generally is desirable. This property is especially interesting since the development in the heating technology is towards increased use of low temperature systems (surface ground heat, solar heat, etc.), and the invention makes it possible to maintain a small size of the convection heater even at a low temperature of the heating medium. Another object of the invention is to obtain the greatest possible effect of a given amount of material for the disc system which - in combination with manufacturing simplicity - makes the product less expensive and of lighter weight. In another aspect the invention aims at providing a convection heater which can easily be mounted at the place of use. A further, and related, object is to provide a convection heater which is built up from a small number of multifunctional parts, which e.g. can be turned so that the same disc package can be used for right hand and left hand mounting in one and the same cover, make it possible to mount both a single and a double disc package in one and the same cover, provide for convenient exchange of the cover and the disc package when damaged, etc., which - in addition to the simplicity of mounting - offers advantages as to stock- keeping. In a further aspect the invention aims at providing a convection heater which because of its low heat contents (a small amount of material, a small volume of circulating water) is energy saving and permits rapid and adaptive temperature control, this in contrast to closed systems having high heat contents. In summary, the invention thus aims at providing an overall solution of the problem of providing a convection heater which is cheap, efficient and simple from many aspects.
These and other objects of the invention are achieved by giving a convection heater the characteristic features which are indicated in the subsequent claims and are explained further below with reference to the enclosed drawings, wherein

Figure 1 is a pespective view of one embodiment of a convection heater according to the invention arranged for wall-mounting,
Figure 2 is schematic view in longitudinal section of the convection heater of Fig. 1 (with the midportion left out),
Figure 3 is a schematic bottom view of a wall- mounted convection heater according to the invention,
Figure 4 is a perspective view of two adjacent discs for the convection heater according to the invention,
Figure 5 is a perspective view showing two convection heaters according to the invention interconnected for floor-mounting, and
Figure 6 is a bottom view of an alternative embodiment of the convection heater according to the invention, provided with double disc packages.

The convection heater according to the invention shown in Figures 1 to 3 comprises a convector cover 1 in which there is a disc package 2 comprising a plurality of adjacent convector discs 2a, 2b ....... 2n. The specific design of the discs will be explained further below in connection with Fig. 4. The disc package 2 is carried by a tube system 3 for circulation of the hot water forming the heat source. In the embodiment shown in Figs. 1-3 the tube system 3 comprises two substantially parallel tube parts 3a and 3b extending through the disc package 2 in close contact therewith. The tubes 3a and 3b are series connected by means of a coupling part 4, and they open into two couplings 5a and 5b respectively for connection to conventional fed water conduits. At the interconnection between the tube branches 3a and 3b a thermostate is inserted into the tube system in a manner which is per se conventional, for adjusting the flow in the system in relation to the adjustment of a thermostate setting knob 7. At the thermostate end of the tube system the same is provided with a screw receiving piece 8 for simple attachment thereof to the cover 1 by means of a screw 9. The tube system 3 is further in per se conventional manner provided with a de-airator 10, which in the illustrated embodiment is interconnected between the tube part 3a and the coupling 5a, i.e. at the opposite end compared to the thermostate 6, 7. The de-airator 10 has a valve body 11 passing through a corresponding opening in the cover 1. The valve body 11 serves as a second suspension point for the tube system 3 (with the attached disc package 2) in the cover 1.. Because the valve body 11 can slide freely in the longitudinal direction in a corresponding opening in the cover, no thermal stress is transferred from the tube system 3/the disc package 2 to the cover 1, which otherwise would suffer the risk of being distorted. Of course, the mobile suspension of the tubes/disc package does not have to be by means of the de-airator valve body 11 - although this has proven to be especially advantageous - but one can as an alternative make use of any separate suspension body on the tube system, which can move freely in the longitudinal direction in a corresponding opening in the cover.
In order to ensure correct orientation of the tube system 3/the disc package 2 within the cover it is preferred to provide suitable guide means at a further point. As is best seen from Fig. 3 the tube system is, in the shown embodiment, close to the connection end 5a provided with a guide tongue 12 projecting in the longitudinal direction of the convector and being arranged in a corresponding slot 13 in the cover 1. Correspondingly as for the valve body 11, the guide tongue 12 is arranged to move freely in the slot 13 in order not to transfer thermal stress to the cover.
The cover 1, which forms part of the convection heater according to the invention, is formed as an integral unit and thus does not require mounting of separate parts, as is the case in some known convection heaters. The cover 1 essentially consists of a front plate 1a, two side plates 1b and 1c respectively, a top grid 1d having a large opening area for discharging heated air, and inwardly folded edge portions 1e at the bottom side. The disc package 2 (and the tube system 3) in this manner become substantially invisible from the outside. This means i.a. that the disc package 2 does not have to be designed and dimensioned with regard to visual aspects, but can be designed in a manner maximizing the heating aspects.
As mentioned above one of the advantages of the convection heater according to the invention is that the tube system 3/the disc package 2 can be mounted in a reversed position in one and the same convector cover 1. To this end the side plate 1b is not only provided with holes for receiving the thermostate 6, 7 and the attachment screw 9, but also with a hole for receiving the suspension valve body 11 (or any alternative separate suspension body), suitably covered by a discreet cover plate 14. In analogous manner the side plate 1c is provided with holes for receiving the thermostate 6, 7 and the screw 9, which holes are suitably covered with corresponding discreet cover plates 15 and 16 respectively. For the analogous purpose the bottom edge 1 e at the side plate 1 is provided with a slot 13a (corresponding to the slot 13) for receiving the guide tongue 12 when reversing the tube system 3/disc package 2. Of course, these through-holes do not have to be made in advance, but they can be provided in connection with the mounting, the need for cover plates then being eliminated.
The cover 1 is finally provided with wall brackets 17 which preferably have a special design for facilitating the mounting of the convection heater. According to this preferred embodiment the brackets 7 have the form of profile lists, in which holes for screws or analogous fastening means 18 are provided. The screw holes in the attachment lists 17 are inclined inwards, so that the screws etc. are easily accessible for attachment to a wall V without being hindered by the cover 1, in spite of the fact that the attachment lists 17 are essentially inside the plane of the side plates 1b and 1c respectively (see Fig. 3). In this manner there is obtained a very simple and rapid mounting of the convector, while at the same time the attachment lists 17 to a great extent are concealed behind the convector. The inclined nailing also means that the fastening becomes very stable, and there is no need for any mid- support.
The convection heater according to the invention can be connected to a single-tube feed water system (i.e. the couplings 5a and 5b are connected. to one and the same water feed tube) as well as to a double-tube feed water system (i.e. the couplings 5a and 5b are connected to one feed tube each). The most essential difference between these two types of feed water systems is that, in the former case, a comparatively great part of the supplied hot water has to by-pass the tube system 3. In order to facilitate the shifting between these feed systems, the convection heater according to the invention is preferably provided with a by-pass conduit 19 at the couplings 5a and 5b. The conduit 19 is provided with a valve which can easily be adjusted from the exterior by means of a set screw 20. In known convection heaters one has to exchange a corresponding valve for changing between the single-tube and the double-tube systems, but in this case it is sufficient to turn the screw between two marked positions, e.g. by turning the screw 20 by 90°.
An essential part of the convection heater according to the invention is the design of the discs and the disc package 2, and this aspect will be explained further in connection with Fig. 4. This Figure shows two adjacent convector discs 2a and 2b. Each disc substantially consists of a thin metal plate of e.g. aluminum, which has been folded and provided with two substantially trapezoidal corrugations 21 and 27 and substantially perpendicular side portions 23 and 24 respectively. Each side portion 23 and 24 terminates in a short, inwardly extending abutment portion 25 and 26 respectively. In the planar mid- portions 27 of the discs there are punched-out through-holes for the tubes 3a and 3b. These through-holes are provided with contact collars 28a and 28b respectively, formed during the punching operation.
As mentioned above it is according to the invention essential that the discs 2a, 2b, etc. are thin and have comparatively large surface areas, and that adjacent discs between themselves form a channel 28, which is closed at the sides and through which the air to be heated passes by self- draft ("chimney effect"). In the shown, especially preferred embodiment the discs have a thickness in the range of about 0.2 to 0.35 mm, which has proven to be optimal saving of material and a good efficiency. The convection channels 28 are formed in that the abutment edge 25 of one disc abuts a second abutment edge 29 of an adjacent disc. For optimal convection flow it is essential that the corrugations or folds 21 and 22 extend in the longitudinal direction of the channel 28. Another essential factor for the efficiency of the convection heater according to the invention is the graduation d, i.e. the distance between two adjacent discs. The graduation optimum i.a. depends on the disc width b, the disc height h and the design of the grooves 21, 22. According to the invention the graduation d should preferably be 10-30% of the disc width b and preferably 3-12% of the height h in the shown embodiment comprising two grooves. Especially advantageous values of the discs is a graduation d of about 10 mm for disc width of about 50 mm. The optimal height h is then about 200 mm, but very good results are, for example, also achieved with heights down to about 100 mm and up to about 300 mm.
Another essential condition for achieving high efficiency in the convection heater according to the invention is that the discs are firmly secured to the tubes 3a, 3b, in which the heat carrying water circulates, so as to provide good heat transfer between the tubes and the discs. This is suitably achieved in that a desired number of discs are threaded onto the tubes 3a, 3b and kept in contact with each other, the tubes then being expanded, e.g. mechanically, in a manner known per se. In doing so one does not only achieve good contact between the tubes and the discs, but also that the discs are secured relative to each other while forming the convection channels 28.
Fig. 5 illustrates a further example of the flexibility of the convector system according to the invention, viz. how two convection heaters in simple manner can be combined for floor-mounting (in contrast to wall-mounting according to Fig. 3) using the same cover as earlier described. Two covers 1 (with the tube system 3 and disc package 2 suspended therein) are arranged with the backs facing each other, so that the planar attachment surfaces 17a of the attachment lists 17 contact each other. A floor support 30 comprises a hollow vertical holder body 31, which at the bottom is secured to a floor attachment plate 32 and at the top has a cover plate 33. The cavity formed in the body 31 is adapted to receive the attachment lists 17 of the two covers 1, with the surfaces 17a thereof contacting each other for stability of the joint. The attachment lists 17 are secured relative to each other and to the holder body 31 in suitable manner, e.g. by means of bolted joints (not shown). Although both convectors in Fig. 5 can be connected separately to feed water conduits, it is preferred to interconnect the two convectors, e.g. by means of the connections 5a, 5b, so that the connection to the feed water conduits is similar to that of a separate convector. The interconnection of the two convectors can be designed in analogy with that which will be described in connection with Fig. 6.
Fig. 6 further illustrates the flexibility of the convector system according to the invention. In this embodiment two disc packages 2' and 2" are mounted side-by-side in a common cover 1, which can be identical with the cover used in the preceding embodiments. The convector shown in Fig. 6 is designed fully in analogy with the convector according to Figs. 2 and 3, which only has one disc package 2. The differences are that in this case dual upper conduits 3'a and 3"a and dual lower conduits 3'b and 3"b are utilized. Further, the lower tubes 3'b and 3"b are interconnected via a tube bend 3c, the lower tube 3'b is connected to the upper tube 3"a via a tube bend 3d, and the upper tube 3'a is connected to the upper tube 3"a via a tube bend 3e, to which also the thermostate 7 is connected. It should in particular be noted that the "dual convector" according to Fig. 6 utilizes the same cover having the same through-openings for thermostate, attachment screw and de-airation valve or the like, and also the same guide slots (it should, however, be noted that Fig. 6 shows a somewhat modified location of these through-holes as an alternative). Also the dual convector according to Fig. 6 can thus be reversed for right hand or left hand mounting.

Claims

1. A space heater of convector type comprising at least one disc package, a tube system which carries the disc package and through which hot water is arranged to flow, each disc package comprising a plurality of parallel discs (2a .... n), which are attached to the tube or tubes in heat transferring contact therewith, adjacent discs contacting each other and forming vertical convection channels for heated air therebetween, characterized by a convector cover (1), which forms a continuous unit and surrounds and essentially conceals the tube sysem (3) and the disc package or packages (2) carried thereby, and in that the tube system (3) with the disc package or packages (2) carried thereby is loosely suspended in the cover (1), with the disc package or packages (2) spaced apart from the cover (1), in a manner such that thermal stress caused by temperature variations in the tube system and the disc package or packages is not transferred to the cover.

2. A space heater according to claim 1, characterized in that the tube system (3) with the disc package or packages (2) carried thereby is suspended in the convector cover (1) in one suspension point at each end.

3. A space heater according to claim 1 or 2, characterized in that one end of the tube system (3) with the disc package or packages (2) carried thereby is provided with a suspension body (11) which is freely suspended in a corresponding opening in the cover.

4. A space heater according to claim 1, 2 or 3, characterized in that the cover comprises a front plate (1 a) and two opposite side plates (1 b, 1c), in which the tube system (3) and disc package or packages (2) are suspended, and in that an attachment list (17) for fastening the cover to a wall (V) or the like is provided at each side end of the cover, substantially parallel with the corresponding side plate (1b and 1c respectively).

5. A space heater according to claim 4, characterized in that the outer edge of each attachment list (17) is located substantially in the extension of the plane of the corresponding side plate (1 b and 1c respectively) and is provided with at least one inwardly inclined hole for fastening means (18) of the screw type or the like, so that the fastening means can be inserted through the hole by inclined fastening without being hindered by the side plates (1b, 1c).

6. A space heater according to claim 4 or 5, characterized in that each side plate (1b, 1c) is provided with through-openings both for said stationary and said loose suspension of the tube system/disc package or packages, and with through-openings for optional further devices such as a thermostate (7), and in that the unit formed by tube system (3) and disc package or packages (2) is symmetrical in relation to the suspension points (9 and 11 respectively), whereby said unit can be right hand or left hand suspended in the cover (1).

7. A space heater according to any one of the preceding claims, characterized in that each disc contained in said disc package or packages is provided with at least two longitudinal area- increasing depressions (21, 22) and two end portions (23, 24), which extend substantially in parallel with the corresponding tubes (3a, 3b) and which contact corresponding portions of an adjacent disc, and in that each disc has a thickness in the range of about 0.2-0.35 mm, a distance between adjacent discs of about 10-30% of the disc width, and preferably about 3-12% of the disc height.

8. A space heater according to any one of the preceding claims, characterized in that the tube system comprises two series connected, substantially parallel tube sections (3a, 3b), each disc (2a, 2b ....) being arranged on both of said tube sections, and in that the free ends of the tube sections are arranged to be connected to a feed water conduit.

9. A space heater according to claim 8, characterized in that a second tube section (3'a, 3'b), having a second disc package (2') is series connected with the first tube system (3).

10. A space heater according to any one of the preceding claims, characterized in that the tube system (3) is provided with a de-airation valve, the valve body (11) of which serves as said suspension body for free suspension of the tube system (3) i_l1 the cover (1).

11. A space heater according to any one of the preceding claims, characterized in that it comprises a by-pass conduit (19) for by-passing hot feed water directly from the inlet end (5a) of the tube system (3) to its outlet end (5b), and in that the by-pass conduit is provided with a valve, which from the outside of the system can be adjusted between two positions, viz. one position corresponding to connection of the space heater to a dual-tube feed system, and a second position corresponding to connection of the heater to a single-tube feed water system.