IES922745A2 - Further improvements in or relating to environmental safety - Google Patents

Abstract

In a heat exchanger (21) having an upper header (22) and a lower header (23), a number of generally vertical tubes or elements 5 (24) extend between the headers and communicate with the headers for flow of a heat exchange medium between the headers through the tubes. A front panel (33) extends between the upper and lower headers. Each header (22) and (23) is close to the front panel. Heat transfer elements (25) in the form of finned plates are 10 associated with the vertical elements (24). According to the invention, each of the upwardly extending tubes (24) has a first portion (24a) which extends divergingly away from the front panel (33) in an upwards direction from the lower header (23). A second portion (24c) of the element (24) continues from lower portion (24a) 15 upwardly and convergingly outwards towards the front panel (33) to the upper header (22). A bent structure of tube (24) is thus provided, and at least the bend portion (24b) of the tube (24) connecting the lower (24a) and upper (24c) tube portions is at a greater spacing from the front plate (33) then the inclined sections 20 (24a) and (24c).

Description

lower header (23), a number of generally vertical tubes or elements (24) extend between the headers and communicate with the headers for flow of a heat exchange medium between the headers through the tubes. A front panel (33) extends between the upper and lower headers. Each header (22) and (23) is close to the front panel. Heat transfer elements (25) in the form of finned plates are associated with the vertical elements (24). According to the invention, each of the upwardly extending tubes (24) has a first portion (24a) which extends divergingly away from the front panel (33) in an upwards direction from the lower header (23). A second portion (24c) of the element (24) continues from lower portion (24a) upwardly and convergingly outwards towards the front panel (33) to the upper header (22). A bent structure of tube (24) is thus provided, and at least the bend portion (24b) of the tube (24) connecting the lower (24a) and upper (24c) tube portions is at a greater spacing from the front plate (33) then the inclined sections (24a) and (24c).

Figure 3. 25 1012S ΖΓ i 28b IE 922745 ^’aUC4TIOw§ 2 2 7 4 j OPEN TO PUBLIC INSPECTION Ί UNDER ί SECTION 28 AND RULE 23 j JNL. No....Z./..^.^. . 5 /j Further improvements in or relating to environmental safety This invention relates to tubular heat exchangers, in particular for use as radiators in heating systems. The invention is especially directed to a radiation/convection heating unit having a box-like casing containing a generally vertical pipe assembly defined by two horizontal headers interconnected by upwardly directed risers or heating elements.

British Patent Specification No. 946,650 discloses a heat exchanger of this kind in which an upper and lower pipe are interconnected by tubes, each of which has a central rising portion. Heat transfer elements are secured to the tubes and comprise fins for directing the airflow for maximum convective heat transfer. Preferably the heat transfer elements consist of plates, provided with fins, attached one to each side of each upwardly directed tube. The fins are bent out from the plates in such a manner as to form louvre openings appropriately directed for the required convective airflow.

IE 922745 - 2 British Patent Specification No. 2,044,910A provides further variations in heat exchangers of the foregoing kind. This patent specification provides an improved external appearance for a unit of the kind identified above by replacing the louvred front panel arrangement of the earlier design with an apertured or slotted front panel behind which the heat exchange structure itself is disposed.

In a particular construction described in this patent specification, referred to as an extra-deep unit, the heat exchange structure of the radiator includes a diagonally arranged pipe assembly within the casing of the unit by virtue of which enhanced heat exchange is established.

It is an object of the present invention to effect further improvements in units of the foregoing kind by virtue of which a still more favourable external appearance is achieved while yet retaining substantially undiminished the advantageous heat exchange capabilities of units of this kind. It is a specific object of the invention to provide a unit of the foregoing kind in which a substantially planar front panel may be provided, free from apertures, louvres or substantially any opening whatever.

According to the invention, there is provided a heat exchanger comprising, (a) an upper header, (b) a lower header, (c) a plurality of tubes extending between the headers and communicating with each header for fluid flow between the headers by way of said tubes, (d) a front panel extending between the upper and lower headers, each header being in substantial proximity to the said front panel, (e) at least one heat transfer element associated with each of said plurality of tubes, said heat transfer element comprising fins, and IE 922745 - 3 (f) each of said plurality of tubes having a first portion extending divergingly away from said front panel and upwardly from said lower header, said first portion communicating with a second portion of said tube, and said second portion extending in a direction away from said first portion convergingly towards said front panel and upwardly towards the upper header, a bent tube structure being thereby provided, at least a section of said bent tube structure being at a greater spacing from said front panel than those sections of said tube structure connected to said upper and lower headers.

In a favoured embodiment, each of said plurality of tubes may be connected to said upper and lower headers in a portion of the header directed away from said front panel. Suitably, the heat transfer elements consist of plates attached to opposite sides of each tube, the fins being bent out from the plate or plates to define louvre openings therein.

Preferably, the fins of a heat transfer plate located on the inner side of the tube remote from the front panel are downwardly directed and those of a heat transfer plate located on the opposite side of the tube are upwardly directed, these plates being attached to said first portion of the tube. Preferably also, the fins of a further heat transfer plate located on the inner side of the tube remote from the front panel are upwardly directed and those of yet another heat transfer plate located on the opposite side of the tube are downwardly directed, said further and yet another plates being attached to said second portion of the tube.

A known construction of beat exchanger will now be described having regard to certain of the accompanying drawings, together with an embodiment of the improved heat exchanger according to the invention and certain features and variants thereof, again with reference to others of the following drawings.

IE 922745 - 4 In the drawings, Figure 1 is a pictorial representation of a known construction of tubular heat exchanger or radiator, Figure 2 is a cross-sectional end view of the radiator of Figure 1, Figure 3 is a part cutaway view of the improved heat exchanger or radiator according to the present invention, Figure 4 is a cross-sectional end view of the radiator of Figure 3, Figure 5 is a top view in cross-section of one form of front panel for incorporation in the radiator of Figures 3 and 4, and Figure 6 is a schematic representation in cross-sectional end view of an adaptation or modification of the radiator of Figures 3 and 4.

Referring first of all to the known construction of Figures 1 and 2, the heat exchanger 1 includes an upper horizontal or header pipe 2 located substantially vertically above a lower horizontal or header pipe 3. Pipe 2 is a supply pipe and pipe 1 is a discharge pipe. The headers 2 and 3 are interconnected by vertical tubes or elements 4, each of which is welded at the top and bottom respectively to the upper header 2 and the lower header 3. Two heat-conducting plates 5a, 5b are welded onto the opposite sides of the vertical elements or tubes 4. Each plate 5a, 5b is provided with respective outwardly bent fins 6 and 7. The fins 5 of the front plate 5a are downwardly directed, while the fins 7 of the rear or inward plate 5b are arranged to open upwardly. Each plate has two rows of fins between each pair of vertical elements or tubes 4.

The vertical elements 4 are welded to the fronts of the headers 2 and IE 922745 - 5 3, and the array of heat-conducting plates 5a welded to the sides of the vertical elements 4 directed away from the headers define the front face of the radiator or heat exchanger unit 1.

The headers and heating elements are accommodated within a frame structure defined by suitable framework members, and the upper side of this structure is covered over by a grid 8, while the ends are closed in by plates 9, which may optionally also be apertured or louvred. The lower side of the structure may also be enclosed as required.

Referring now in particular to Figure 2, the manner of operation of this heating unit is shown. Radiant heat is directed outwardly from the vertical elements and their attached heat-conducting plates in the direction of arrows 11. Significant convective heat distribution also takes place by virtue of air, heated by contact with the vertical elements and their heat-conducting plates, rising along the front of the unit, where it is engaged by the downwardly directed outer lips of the fins or louvres 6 to be thereby conducted inwardly to pass between the vertical tubes 4 and to then emerge through the upwardly directed fins or louvres of the inner heat-conducting plate 5b. The direction of this airflow is shown by arrows 12. It continues upwardly through the interior of the unit to the top grid 12, where the heated air emerges into the space to be warmed. In engineering terms, this arrangement is highly effective and of substantially greater efficiency than a flat panel radiator. The downwardly directed fins or louvres on the front panel of the radiator break up any boundary layer of air inclined to develop along this front face. In addition, there is less diminution in the thermal gradient or temperature difference between the radiator and the air immediately adjacent to it as between the bottom and top of the radiator than is the case for a panel construction of heat exchanger. The arrangement and disposition of the louvres is highly effective in generating effective convective heat transfer.

IE 922745 - 6 In visual terms however the finned front panel of this radiator has proved to be less attractive to the consumer than the clean and neat lines of a panel or like type construction. A number of options have been exercised to provide a unit having substantially similar efficiency to that of Figures 1 and 2, while yet having a better quality of appearance. One such alternative is described in British Patent Specification No. 2,044,910A, where the louvred heat exchange elements are enclosed behind a slotted vertical front panel. In a particular arrangement described in this specification and shown in Figure 10, under the designation of an extra-deep unit, a dual pipe assembly is used, in which an inner or rearwardly located diagonally disposed pipe assembly, provided with a single louvred heat exchange panel, operates in conjunction with a vertically disposed similar such structure, located immediately behind the slotted front panel. Inward airflow takes place through the slotted front panel and the front vertical louvred heat exchange elements somewhat similarly to the arrangement of Figures 1 and 2 above, while a chimney-type airflow takes place upwardly through the base of the unit, which is open for airflow, through the diagonally located rear heat exchange elements, and out through the top of the unit.

While meeting to a certain degree aesthetic considerations in combination with engineering efficiency, a significant disadvantage of this construction is the relatively substantial depth resulting from the use of two heat exchange structures or registers, each consisting of a pair of header pipes and interconnecting heat exchange elements with attached apertured plates.

The present invention aims to overcome disadvantages of this known construction, while retaining the technical efficiency of the register structure in which upwardly extending heat exchange elements function in conjunction with attached louvred plates for enhanced convective heat transfer.

IE 922745 - 7 Referring now to Figures 3 and 4, which show the improved heat exchanger according to the present invention, the unit 21 again comprises upper and lower headers 22 and 23 respectively, again linked by generally upwardly directed elements 24, welded at the top and bottom to the upper and lower headers 22 and 23. However, as distinct from the construction of Figures 1 and 2, the elements 24 are in this instances welded to the rear or inner sides of the headers 2 and 3. Each element 24 also has a kinked or bent construction, in which it has a lower or first portion 24a, which extends upwardly and inwardly or rearwardly from the lower header 23, to a bend or curved portion 24b, approximately half way along the element 24 between the upper and lower headers 22 and 23, and is then continued from bend 24b by virtue of an outwardly and forwardly extending upper portion 24c to its upper end, where it is welded to the upper header 22. Each pair of elements 24 is again provided with heat-conducting plates 25, welded onto the front and rear. The plates 25 are now however not continuous from the top of the structure to the bottom, but separate plate portions are affixed to the upper and lower straight runs of the elements 24, the bend region 24b not having plates 25 attached to it. The plates 25 are again provided with fins 26 and 27, as in the case of the previous construction.

The front of the unit is however closed off by a separate front plate 33, further details of which will subsequently be described. The top and bottom of the unit are closed off by upper and lower grids 28a and 28b respectively. Thus within the unit, behind the front plate 33, a chimney-like structure is established for upward airflow through grid 28a into the interior of the unit, past the heat-conducting structure 25, 26, 27, and out through the upper grid 28b.

The airflow arrangement is shown in Figure 4. In order to maximise heat transfer by convection, the finned structure in this improved unit differs from that of the arrangement of Figure 1. The IE 922745 - 8 lower inner heat-conducting plate 25a, on the portion of the pipe which extends inwardly and upwardly from lower header 23, has downwardly directed fins 26a, these catching rising air and diverting it forwardly between the elements 24 to front lower plate 25b, which is provided with upwardly opening fins 27a. Air emerging from these fins flows upwardly through a space generally of triangular cross-section between the plates 25 attached to the elements 24 and the front plate or panel 33. Fins 26b on the front plate 25c of the upper outwardly extending runs 24c of elements 24 are directed downwardly, so that the air rising within the triangular space is again taken in through the fins 26b, between the upper runs 24c of the elements 24, and then outwardly directed again by fins 27b of upper inner or rear plates 25d, these fins opening in an upward manner. Discharge of air then takes place through upper grid 28b.

A chimney effect thus prevails between panel 33 and the wall 37 to which the radiator is attached. Approximately 85% of the efficiency of the unit of Figures 1 and 2 may be achieved, but within a relatively shallow unit which may be as narrow as 70 mm between front panel and wall, and also within a structure having enhanced visual appeal and conforming in external appearance closely to established panel radiator designs.

Figure 5 shows a top view of a front panel structure, suitable for use in the radiator of Figures 3 and 4. The panel 33 has a flat plate portion 34, backed by channel or tubular sections 35 and 36 respectively, to provide it with stiffness. Suitably, these sections extend vertically from the top to the bottom of the plate or panel 33. The tubular section 36, where provided, may be closed at each end, to provide an enclosed air space.

Figure 6 shows a structural variant of the invention in a view similar to that of Figure 4, but in diagrammatic terms only.

As shown in Figure 4, the bend in the upward elements 24 occurs approximately halfway between the upper and lower headers. While IE 922745 - 9 such a placement of the bend may be advantageous in manufacturing terms and relatively convenient for standardisation, the invention is not limited to such a bend location. In the arrangement 41 shown in Figure 6, the bend in the element 44 is located closer to the lower header pipe 43 than it is to the upper header 42, as indicated by the dimension identified by reference letter A. The placement of this bend may be varied to substantially optimise the efficiency of convective heat transfer. As shown in Figure 6, the bend is approximately one-third the height of the unit, but other positions may be chosen.

IE 922745

Claims (6)

1. A heat exchanger comprising, (a) an upper header, 5 (b) a lower header, (c) a plurality of tubes extending between the headers and communicating with each header for fluid flow between the headers by way of said tubes, (d) a front panel extending between the upper and lower headers, 10 each header being in substantial proximity to the said front panel, (e) at least one heat transfer element associated with each of said plurality of tubes, said heat transfer element comprising fins, and 15 (f) each of said plurality of tubes having a first portion extending divergingly away from said front panel and upwardly from said lower header, said first portion communicating with a second portion of said tube, and said second portion extending in a direction away 20 from said first portion convergingly towards said front panel and upwardly towards the upper header, a bent tube structure being thereby provided, at least a section of said bent tube structure being at a greater spacing from said front panel than those sections of said tube structure 25 connected to said upper and lower headers.

2. A heat exchanger according to Claim 1, wherein the heat transfer elements consist of plates attached to opposite sides of each tube, the fins being bent out from the plate or plates to define 30 louvre openings therein.

3. A heat exchanger according to Claim 2, wherein the fins of a heat transfer plate located on the inner side of the tube remote from the front panel are downwardly directed and those of a heat transfer 35 plate located on the opposite side of the tube are upwardly directed. !E 922745 - 11

4. A heat exchanger according to Claim 2 or Claim 3, wherein the fins of a heat transfer plate located on the inner side of the tube remote from the front panel are upwardly directed and those of a heat transfer plate located on the opposite side of the tube are 5. Downwardly directed.

5. A heat exchanger substantially as hereinbefore described with reference to Figures 3 and 4 of the accompanying drawings, or these Figures taken together with Figure 5, or these Figures as

6. 10 modified by Figure 6.