GB2098312A - Heating apparatus - Google Patents

Abstract

A heating unit is provided for a calorifier (especially a water heater), the unit including a series of concentric tube-pairs (4, 7) which are vertically arranged, the outer tubes (4) fluidly communicating with supply and discharge manifolds (5, 6) for heating fluid. In operation water (or other fluid) of the calorifier passes upwardly in the inner tube (7) and is heated by heating fluid (e.g. hot air) in the annular space between the tubes, and additionally this heating fluid heats the water surrounding the outer tubes. Both the tubes (4, 7) can carry fins to improve heat transfer, and the tubes can be of copper or other material of good heat transfer property. The arrangement provides improved heat transfer performance. <IMAGE>

Description

SPECIFICATION Improved heating apparatus The present invention relates to heating apparatus for use in heating liquid in heating vessels such as calorifiers.

Calorifiers serve for the heating of liquid e.g.

water and generally utilise a heat exchange coil within the calorifier vessel through which passes heating fluid, e.g. hot gas. Efficiency of heat exchange depends on a suitable heat exchange surface area, and this is particularly the case where there is a low temperature differential between the heating and heated fluids. It is the main object of the present invention to provide heat exchange apparatus for a calorifier or the like providing effective heat exchange even when there is a low temperature differential between the fluids.

According to the present invention heating apparatus comprises a first heat exchange conduit for throughflow of a first fluid and serving to provide heat exchange between said first fluid and a second fluid external of the conduit, and a second heat exchange conduit within said first conduit for throughflow of said second fluid or another fluid whereby heat exchange occurs between the first fluid and the fluid within said second conduit.

Preferably heat transfer elements are provided on the conduits to encourage heat transfer, and in particular these elements are preferably provided between the second conduit and an internal wall of the first conduit.

Preferably the heat transfer elements comprise fins.

The present invention is also a calorifier provided with the above heating apparatus.

An embodiment of the present invention will now be described by way of example with.

reference to the accompanying drawings wherein Figs. 1 to 3 show views of heat exchange apparatus and Fig. 4 shows the heating apparatus located in a calorifier. The heat exchange apparatus comprises heating units 1 joined by pipe 2, 3, each unit 1 including a series of vertical tubes 4 connecting inlet manifold 5 and outlet manifold 6, and a series of second heat exchange tubes 7 extend within the tubes 4 and intake and discharge externally of the manifolds 5, 6 at 8, 9 respectively, the tubes 7 being fluidly sealed from the interior of the unit 1. The units 1 carry heat exchange fins 10, specifically in the tubes 4, while fins 11 are located on the tubes 7 so as to be located in the annular space 12 between the tubes 4, 7.The tubes 4, 7 can comprise Integron (TM) high fin tubes: fins 11, 10 may have diam. of 22 mm (outer) and 28 mm (inside) respectively.

Heating gas e.g. hot air is supplied to the units 1 via inlet 12 and discharges at 13.

The calorifier 14 shown in Fig. 4 utilises the above heating apparatus and the heated liquid e.g.

water in addition to surrounding the units 1 flows in tubes 7.

The above heating apparatus provides a large surface area heat exchanger which is particularly beneficial for a low air/water temperature differential. The arrangement gives excellent heat transfer to the water from the hot air that flows between the tubes 4, 7 and essentially doubles the effective heat transfer surface between the air/water in comparison with a similarly sized previous heat exchanger, so that the size of the heat exchanger may be considerably reduced for a given heat transfer rate.

The fins 11 of the inner tube 7 cause the air passing in space 1 2 to become turbulent and consequently reduces the rate of air flow, thus providing for more efficient heat transfer to the water within tube 7 and at the same time to the water external of the unit 1.

Modifications are of course possible. Thus more than two units could be used and the units could be arranged in series rather than in parallel. The conduit/manifold arrangement of the unit could be substantially modified.

1. Heating apparatus comprising a first heat exchange conduit for throughflow of a first fluid and serving to provide heat exchange between said first fluid and a second fluid external of the conduit, and a second heat exchange conduit within said first conduit for throughflow of said second fluid or another fluid whereby heat exchange occurs between the first fluid and the fluid within said second conduit.

2. Heating apparatus as claimed in Claim 1, wherein heat transfer elements are provided on the conduits to encourage heat transfer.

3. Heating apparatus as claimed in Claim 2, wherein the heat transfer elements are provided between the second conduit and an internal wall of the first conduit.

4. Heating apparatus as claimed in Claim 2 or 3, wherein the heat transfer elements comprise fins.

5. Heating apparatus as claimed in any one of the preceding claims, including a heating unit comprising a plurality of said first heat exchange conduits arranged in parallel and fluidly connected to a common supply manifold.

6. Heating apparatus as claimed in Claim 5, wherein said first heat exchange conduits discharge into a common discharge manifold.

7. Heating apparatus as claimed in Claim 5 or 6, wherein second heat exchange conduits associated with respective first conduits discharge externally of the manifold or manifolds.

8. Heating apparatus as claimed in any one of Claims 5 to 7, wherein a plurality of said heating units are provided, the respective manifolds of which are connected by linking conduit means.

9. Heating apparatus as claimed in any one of the preceding claims, wherein heat transfer fins are provided on the external surface of the first conduits.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (11)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Improved heating apparatus The present invention relates to heating apparatus for use in heating liquid in heating vessels such as calorifiers. Calorifiers serve for the heating of liquid e.g. water and generally utilise a heat exchange coil within the calorifier vessel through which passes heating fluid, e.g. hot gas. Efficiency of heat exchange depends on a suitable heat exchange surface area, and this is particularly the case where there is a low temperature differential between the heating and heated fluids. It is the main object of the present invention to provide heat exchange apparatus for a calorifier or the like providing effective heat exchange even when there is a low temperature differential between the fluids. According to the present invention heating apparatus comprises a first heat exchange conduit for throughflow of a first fluid and serving to provide heat exchange between said first fluid and a second fluid external of the conduit, and a second heat exchange conduit within said first conduit for throughflow of said second fluid or another fluid whereby heat exchange occurs between the first fluid and the fluid within said second conduit. Preferably heat transfer elements are provided on the conduits to encourage heat transfer, and in particular these elements are preferably provided between the second conduit and an internal wall of the first conduit. Preferably the heat transfer elements comprise fins. The present invention is also a calorifier provided with the above heating apparatus. An embodiment of the present invention will now be described by way of example with. reference to the accompanying drawings wherein Figs. 1 to 3 show views of heat exchange apparatus and Fig. 4 shows the heating apparatus located in a calorifier. The heat exchange apparatus comprises heating units 1 joined by pipe 2, 3, each unit 1 including a series of vertical tubes 4 connecting inlet manifold 5 and outlet manifold 6, and a series of second heat exchange tubes 7 extend within the tubes 4 and intake and discharge externally of the manifolds 5, 6 at 8, 9 respectively, the tubes 7 being fluidly sealed from the interior of the unit 1. The units 1 carry heat exchange fins 10, specifically in the tubes 4, while fins 11 are located on the tubes 7 so as to be located in the annular space 12 between the tubes 4, 7.The tubes 4, 7 can comprise Integron (TM) high fin tubes: fins 11, 10 may have diam. of 22 mm (outer) and 28 mm (inside) respectively. Heating gas e.g. hot air is supplied to the units 1 via inlet 12 and discharges at 13. The calorifier 14 shown in Fig. 4 utilises the above heating apparatus and the heated liquid e.g. water in addition to surrounding the units 1 flows in tubes 7. The above heating apparatus provides a large surface area heat exchanger which is particularly beneficial for a low air/water temperature differential. The arrangement gives excellent heat transfer to the water from the hot air that flows between the tubes 4, 7 and essentially doubles the effective heat transfer surface between the air/water in comparison with a similarly sized previous heat exchanger, so that the size of the heat exchanger may be considerably reduced for a given heat transfer rate. The fins 11 of the inner tube 7 cause the air passing in space 1 2 to become turbulent and consequently reduces the rate of air flow, thus providing for more efficient heat transfer to the water within tube 7 and at the same time to the water external of the unit 1. Modifications are of course possible. Thus more than two units could be used and the units could be arranged in series rather than in parallel. The conduit/manifold arrangement of the unit could be substantially modified. CLAIMS

1. Heating apparatus comprising a first heat exchange conduit for throughflow of a first fluid and serving to provide heat exchange between said first fluid and a second fluid external of the conduit, and a second heat exchange conduit within said first conduit for throughflow of said second fluid or another fluid whereby heat exchange occurs between the first fluid and the fluid within said second conduit.

2. Heating apparatus as claimed in Claim 1, wherein heat transfer elements are provided on the conduits to encourage heat transfer.

3. Heating apparatus as claimed in Claim 2, wherein the heat transfer elements are provided between the second conduit and an internal wall of the first conduit.

4. Heating apparatus as claimed in Claim 2 or 3, wherein the heat transfer elements comprise fins.

5. Heating apparatus as claimed in any one of the preceding claims, including a heating unit comprising a plurality of said first heat exchange conduits arranged in parallel and fluidly connected to a common supply manifold.

6. Heating apparatus as claimed in Claim 5, wherein said first heat exchange conduits discharge into a common discharge manifold.

7. Heating apparatus as claimed in Claim 5 or 6, wherein second heat exchange conduits associated with respective first conduits discharge externally of the manifold or manifolds.

8. Heating apparatus as claimed in any one of Claims 5 to 7, wherein a plurality of said heating units are provided, the respective manifolds of which are connected by linking conduit means.

9. Heating apparatus as claimed in any one of the preceding claims, wherein heat transfer fins are provided on the external surface of the first conduits.

10. A calorifier including heating apparatus as claimed in any one of the preceding claims.

11. A heat exchanger substantially as hereinbefore described with reference to and as illustrated in any one of the accompanying drawings.