IES930452A2 - Additional improvements in or relating to environmental¹safety - Google Patents

Abstract

In a low surface temperature heat exchanger (1) such as a low surface temperature radiator or a radiant panel, substantially flat tubes (3) 10 define a front panel (2) of the radiator, eachflat tube (3) being closed at its axial ends to define an air space. D-shaped ducts (4) for the heating medium extend between headers (7) and (8), and the flat face (5) of each D-shaped duct (4) is in conductive contact with a rear flat face (6) of a respective air-space-defining flat tube 15 (3). Alternatively, the ducts may be profiled for conductive contact with the air space members (3) where adjoining members (3) abut one another. A fin structure (9) for augmenting convective heat transfer may also be attached to the rear of the low temperature or radiant panel (2), the fin structure being profiled (11) to fit over the 20 ducts (4) while yet also being in heat conductive relationship with the panel flat tubes (3)

Description

ADDITIONAL IMPROVEMENTS IH OR RELATING TO ENVIRONMENTAL SAFETY This invention relates to heat exchangers. In particular the invention relates to heat exchangers of the radiator type for use in space heating. The invention is especially directed to low surface temperature space heating units and to radiant panels, in which the same technical requirements apply as are necessary in a low surface temperature unit.

Low surface temperature radiators are provided in situations where unrestricted access to a high temperature radiator or heat exchanger is unacceptable. It is known to cover heat emitters or pipes in such cases using steel mesh, steel sheet or wooden panels. In a specific prior arrangement, there is provided a thermal security arrangement for restricting access to a heat emitting means such as a radiator, in which panel means are mounted at a spacing from the heat emitting means so that a first face of the panel means is directed towards the heat emitting means and a second face of the panel means is directed towards a region to be heated, the panel means having at least one enclosed internal air space located between said faces so that a temperature gradient is established across the panel means between said faces when the heat emitting means is at an elevated temperature relative to the ambient temperature in the region to be heated.

The present invention is especially directed to improvements in IE 930452 - 2 units of this general kind.

According to the present invention, there is provided a low 5 surface temperature heat exchanger comprising at least one duct for carrying a heat exchange medium and panel means having a first face directed towards said at least one duct and a second face directed towards a region to be heated, said at least one duct having a peripheral surface portion in conductive contact with at least a part of said first face of said panel means, and said panel means having at least one enclosed internal air space located between said faces so that a temperature gradient is established across the panel means between said faces when a heat exchange medium at an elevated temperature relative to the ambient temperature in the region to be heated is conveyed through said at least one duct.

Preferably said panel means has a plurality of said air spaces.

In a particular embodiment, said panel means may consist of a plurality of elongate tubular members, each of which is closed at its axial ends, for example by one or more plate portions. Each said tubular member may be non-circular in cross-section, each said member having a first wall portion defining a region of said first face of the panel means and a second wall portion defining a region of said second face of the panel means, said wall portions suitably being substantially planar and parallel. Each said air space is then defined by the interior of a said tubular member. In an especially favoured construction, each said tubular member is formed by rolling a substantially circular tube to achieve the required non-circular cross-section, in which opposed wall portions are substantially planar and parallel.

Suitably a plurality of said ducts are provided, each of said plurality of ducts being in conductive contact with a respective one of said plurality of elongate tubular members of said panel means. Alternatively, two or more of said plurality of ducts may be in conductive contact with a respective one of said plurality of tubular members. The ducts may be substantially D-shaped in cross-section, the flat face of the D being in said conductive contact with the tubular member in each case.

IE 930452 - 3 Alternatively, the ducts may be profiled for conductive contact with the tubular members in notch-shaped regions defined where shorter side wall regions of the tubular members are positioned endwise adjacent to one another to provide an array defining said panel means. Suitably both the ducts and the tubular members are appropriately profiled to substantially optimise said conductive contact.

Thus in a favoured embodiment of the invention in which the tubular members are arranged in parallel juxtaposition to one another to provide a substantially planar or flat array defining said panel means, the ducts suitably extend longitudinally, substantially parallel to the tubular members of the panel means, between spaced apart substantially vertically-extending header tubes. A fin structure for augmenting convective heat transfer from the heat exchanger of the invention may also be attached to the rear of the panel means, the fin structure being profiled to fit over the or each duct while yet being in substantially maximum heat conductive relationship with the panel means.

The number of ducts and/or the dimensions of the duct structure relative to the panel means may be varied within very wide limits, to enable the thermal capacity of the heat exchanger of the invention to be matched to substantially any requirement. Thus the number of ducts may be varied and their conductive relationship with the tubular members of the panel means suited to the particular requirements. The length of the ducts between the header tubes may also be varied, and in particular, their length dimension may be significantly less than the overall longitudinal dimension of the panel means, while also, the unit of the invention may be provided with or without the additional convective fins, depending on the particular installation situation.

According to the invention therefore, there is provided a versatile heat exchanger unit capable of application either as a low surface temperature radiator or as a radiant panel for roof or ceiling mounting. The invention further embraces a heat exchanger, such as a low surface temperature radiator or a radiant panel, substantially as described herein with reference to and as shown in any one or more of the accompanying drawings.

IE 930452 - 4 Embodiments of the invention will now be described by way of example having regard to the accompanying drawings, in which: Figure 1 is a pictorial representation of a unit according to the invention, Figure 2 is a end sectional representational view of a first 10 embodiment of unit according to the invention, Figure 3 shows a variant on the unit of Figure 2, in which rear convective fins are applied to the panel structure, Figure 4 is an enlargement of the manner in which the fin structure is applied to the radiator, Figure 5 shows a modification of the structure in Figure 2, in which two ducts are applied in each case to the rear of each tubular member of the panel means, Figure 6 shows yet a further variant in the invention, in which the ducts are in heat conductive relationship with the tubular members of the panel means, where these are edgewise contiguous in the panel assembly, Figure 7 shows a radiant panel application of the invention comparable to the low surface temperature radiator of Figure 2, Figure 8 shows a radiant panel structure for roof or ceiling mounting comparable with the radiator of Figure 5, and Figure 9 is a radiant panel structure showing the relationship of the ducts and tubular members in an arrangement in which these are engaged where the tubular members meet one another in an edgewise manner.

As shown in Figures 1, 2 and 3, a radiator unit 1 according to the invention consists of a fronting panel unit 2 defined by a plurality of IE 930452 - 5 longitudinally extending flat tubular member 3, each of which is sealed at its ends and defines an internal air space 13, Figure 3. To the rear of each longitudinal tubular member 3, there is located a longitudinally extending duct 4 for a heat exchange medium such as hot water. This longitudinal tubular duct 4 is suitably of D-profile in cross-section, and the flat face 5 of the D is in heat conductive contact, such as by welding, with the rear or inner or inwardly-directed face 6 of a respective tubular member 3 of the panel 10 structure 2. At each end of the array of D-tubes or ducts 4, vertical headers 7 and 8 are provided for bringing the hot water to the ducts 4 and for conveying it away again following its passage through the ducts. Finally, a convective fin structure 9, suitably profiled as indicated at reference 11 to sit neatly in position over the D-tubes or ducts 3, is spot welded 12 (Figure 3) to the panel means 2 and ducts 4, to the rear of the tubular members 3 defining the panel 2.

This unit functions in the following manner. Suitably, the radiator 1 is set into a recess 21 in a wall 22 extending upwardly from a floor 23, such as is indicated in Figure 2, to which reference may now also be directed. Alternatively, the unit 1 may be closed-off at its upper end, against any possibility of access in that region to the heating ducts 4 and fin structure 9. The heat exchange medium flows through the D-shaped ducts 4, and heat is transferred conductively from the ducts 4, to the inner wall 6 of the air spaces 13 (Figure 3) defined by the tubular members 3 of the panel 2. A significant temperature gradient then prevails between the inner 6 and outer 14 (Figure 3) surfaces of these air-filled tubular members, so that the front or exterior face 14 of the unit 1 is at an acceptable temperature from the point of view of the user. Efficiency in transfer of heat to the region in which the radiator 1 is located while yet retaining a low surface temperature on the front face 14 of the unit is enhanced by providing fins 9, such as shown in Figure 1, at the rear of the structure, further heat being conductively transmitted to these fins 9 by the ducts 4, from where it passes by convection into the space to be heated.

Figure 3 shows in particular detail of the manner in which the fins 9 are shaped 11 around the distribution tubes or ducts 4 and are IE 930452 - 6 then spot-welded to the rear faces 6 of the tubular members 3 defining the panel structure 2 and also to the rear or curved faces 15 of the D-shaped tubular heat conveying ducts 4.

Figure 4 shows a modified version of the arrangement of Figures 1, 2 and 3, in which a lesser front to rear dimension of the unit 1 is achieved by dispensing with the rear fins. The unit may therefore be accommodated in a shallower recess 21 of lesser depth than the corresponding or equivalent recess of Figure 2.

Figure 5 shows a further variant, in which each air-containing tubular member 3 has two D-tubes 4 affixed to its rear face 6. A unit of this kind may be constructed to provide a higher thermal output than that of a unit in which just one heating tube 4 is in place for each tubular member 3.

Figure 6 shows a further variant, which may be provided with or without heat distributing fins, in which the heat exchange medium conveying ducts 34 are in this instance not affixed longitudinally to the central regions of the rear faces 6 of the tubular members 3, but rather are interposed in the notch regions 35 where the shorter dimension side wall portions 36 of the flat tubes 3 are disposed contiguous to one another in an edge to edge or edgewise manner. The notches 35 are formed where the curved shorter walls of contiguous or juxtapos ed tubes 3 defining the flat panel array 2 of the unit curve inwardly and towards one another to the line of longitudinal edgewise abutment of adjacent flat tubes. Suitably the heat transfer medium distribution ducts 4 are in this instance modified to provide a pear-shaped cross-section, so that the tapering faces of the narrower end of the pear-shaped cross-section of duct 4 may engage in a heat conductive manner within the notch 35 defined by the converging contiguous side wall portions 36 of the endwise adjacent flat tubular members 3. In a further variant of this embodiment of the invention, both the heat conveying ducts 34 and the notch region 35 side wall portions 36 of the tubular members 3 may be further profiled or shaped so as to match or conform to one another to an even greater extent, and thereby provide an enhanced degree of conductive contact, thus achieving even more effective thermal performance from the unit.

IE 930452 - 7 The system of the invention may also be applied to ceiling radiant panels 41, the embodiments shown in Figures 7, 8 and 9 corresponding to the wall radiator embodiments of Figures 4, 5 and 6 respectively.

The unit-related reference numerals pertinent to the arrangements of Figures 7, 8 and 9 correspond to those of Figures 4, 5 and 6 with the addition of 40. Other features of Figures 7, 8 and 9 are that the unit 41 is in each case accommodatedn arecess or set-back region 61 of the ceiling 62 so that the heat-emitting face 54 of the panel 42 of the unit 41 is substantially alligned with the ceiling level 62, so that a substantially flush^surface appearance is presented to the space to be heated over the entire expanse of the ceiling.

The invention offers certain advantages over previous low surface temperature radiators, in which in certain instances the effectiveness of the low surface temperature arrangements was excessive, to such an extent that the radiators were perceived as insufficiently warm. The improved units according to the invention provide for a more acceptable front surface temperature, while yet meeting all the safety requirements essential in a low surface temperature unit. The invention similarly meets the requirements for a radiant panel, in which the unit is required to provide a relatively low temperature over a large area of heat output. In particular, by matching the profiles of the heat-conveying ducts to the surface profiles of the tubular members, the degree of heat transfer can be controlled to a significant extent. In addition, the size of the rear or heat medium-conveying portion of the structure may be varied within wide limits relative to the front or air-containing panel. In particular, the rear or heat-generating portion of the structure may be significantly smaller in size than the front or air-containing panel.

The vertical height of the rear structure may be varied, as defined by the vertical height of the end headers, while the spacing between the headers may also be varied, this substantially corresponding to the length of the heat exchange elements or tubes. Thus the front panel may be significantly longer than the heat-generating portion at the rear. The convective heat output of the unit may also be significantly varied by changing or modifying the fin profile, where fins are affixed IE 930452 - 8 to the rear of the panel tubes. Further variation in output may be achieved by dispensing with fins completely, as well as which, such an arrangement facilitates an especially compact unit structure.^ In summary therefore, the system of the invention provides in advantageous manner, low surface temperature wall radiators and radiant panels which are particularly effective in performance, in an economical manner, the system involving the use of a relatively small number of substantially standardised components capable of assembly in a multiplicity of manners, depending on the technical requirements.

Claims (5)

1. A low surface temperature heat exchanger comprising at least one duct for carrying a heat exchange medium and panel means having a first face directed towards said at least one duct and a second face directed towards a region to be heated, said at least one duct having a 10 peripheral surface porttun Ίπ conductivecontact with at least a part of said first face of said panel means, and said panel means having at least one enclosed internal air space located between said faces so that a temperature gradient is established across the panel means between said faces when a heat exchange medium at an elevated 15 temperature relative to the ambient temperature in the region to be heated is conveyed through said at least one duct.

2. A heat exchanger according to Claim 1, wherein said panel means comprises a plurality of elongate tubular members and a plurality of 20 said ducts, each said tubular member being closed at its axial ends and non-circular in cross-section, and having a first wall portion defining a region of said first face of the panel means and a second wall portion defining a region of said second face of the panel means, said wall portions being substantially planar and parallel, and each of said 25 plurality of ducts being in conductive contact with a respective one of said plurality of elongate tubular members.

3. A heat exchanger according to Claim 2, wherein the ducts are profiled for conductive contact with the tubular members in 30 notched-shaped regions defined where the shorter side wall regions of the tubular members are positioned endwise adjacent to one another in an array defining said panel means.

4. A heat exchanger according to any of Claims 1 to 3, comprising a 35 fin structure for augmenting convective heat transfer, wherein said fin structure is attached to the rear of the panel means and is profiled to fit over the or each duct while yet being in heat conductive relationship with the panel means. IE 930452 - 10

5. A heat exchanger such as a low temperature radiator or a radiant panel, substantially as described herein with reference to and as shown in any one or more of the accompanying drawings.