WO2003074933A2

WO2003074933A2 - Gas radiator

Info

Publication number: WO2003074933A2
Application number: PCT/IT2003/000127
Authority: WO
Inventors: Ilario Niboli
Original assignee: Fondital Fonderie Italiane Nuova Valsabbia S.P.A.
Priority date: 2002-03-04
Filing date: 2003-03-04
Publication date: 2003-09-12
Also published as: AU2003219519A1; WO2003074933A3; ITMI20020446A1; ITMI20020446A0; AU2003219519A8

Abstract

A gas radiator (1) is equipped with a gas burner (4); a combustion chamber (3) having a casing (16) extending about an axis (A); a heat exchanger (5) connected to the combustion chamber (3); and a fan (6) for directing a stream of air over the outside of the casing (16) and the heat exchanger (5), which has at least two pipes (18) supplied in parallel with the fumes from the combustion chamber (3).

Description

GAS RADIATOR

TECHNICAL FIELD The present invention relates to a gas radiator.

More specifically, the present invention relates to a gas radiator for direct room heating.

BACKGROUND ART

A gas radiator for direct room heating comprises a burner, a combustion chamber, a heat exchanger, and a fan for directing a stream of air over the combustion chamber and heat exchanger. In contact with the combustion chamber and heat exchanger, the air stream withdraws heat, which it distributes by convection to the surrounding environment .

The heat exchanger of a gas radiator is normally defined by a normally cylindrical pipe with external fins parallel to the air stream produced by the fan. To increase the exchange surface between the fumes and the air stream, a large-diameter heat exchanger pipe and an extensive finning surface area are called for, thus increasing the size of the exchanger and, consequently, of the gas radiator. DISCLOSURE OF INVENTION

It is an object of the present invention to provide a gas radiator enabling a reduction in size, and at the same time featuring a heat exchanger ensuring effective heat exchange .

According to the present invention, there is provided a gas radiator comprising a gas burner; a combustion chamber having a casing extending about an axis; and a fan for directing a stream of air over the outside of said casing and a heat exchanger; the gas radiator being characterized in that the heat exchanger comprises at least two pipes supplied in parallel with the fumes from the combustion chamber.

The gas radiator according to the invention is particularly advantageous by employing a number of small- diameter pipes, as opposed to one large-diameter pipe, and by enabling greater freedom in the arrangement of the pipes, to obtain a relatively compact gas radiator and good thermal exchange efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

A number of non-limiting embodiments of the present invention will be described by way of example with reference to the accompanying drawings, in which:

Figure 1 shows a side view, with parts removed for clarity, of a gas radiator in accordance with the present invention;

Figure 2 shows a view in perspective, with parts in section and parts removed for clarity, of the combustion chamber of the Figure 1 gas radiator;

Figure 3 shows a partly exploded view in perspective, with parts in section and parts removed for clarity, of the heat exchanger in Figure 1. BEST MODE FOR CARRYING OUT THE INVENTION

Number 1 in Figure 1 indicates as a whole a room- heating gas radiator.

Radiator 1 comprises a frame 2 defined by a supporting plate, to which are fitted a combustion chamber 3, a burner 4, a heat exchanger 5, a fan 6 for directing a stream of air over the outside of combustion chamber 3 and heat exchanger 5, a fan 7 for feeding combustion air into combustion chamber 3, and a control unit 8. A gas pipe 9 connects the gas mains (not shown) to burner 4.

Chamber 3 extends in a horizontal direction Dl along a substantially horizontal axis A, and is connected directly to burner 4, and via a header 10 to heat exchanger 5. Combustion chamber 3 and exchanger 5 have respective fins 11a and lib extending perpendicularly to axis A to direct the air stream from fan 6 in a substantially vertical direction D2 and increase heat exchange. Fins 11a and lib are equally spaced with a spacing P in direction Dl, and each fin 11a is aligned with a fin lib.

With reference to Figure 2, combustion chamber 3 comprises an inlet 12; an outlet 13; and a flow section S, which is perpendicular to axis A and substantially rectangular with the long sides parallel to direction D2. Inlet 12 and outlet 13 are surrounded by respective flanges 12a and 13a; and chamber 3 is defined by four flat walls 14 and 15, two of which (walls 14) are parallel, while the other two (walls 15) converge towards outlet 13 so that section S is minimum at outlet 13 and maximum at inlet 12. Flange 13a is connected to header 10; flange 12a is connected directly to burner 4; and walls 14 and 15 define a casing 16 extending about axis A.

With reference to Figure 3 , the heat exchanger comprises a one-piece body 17 made of metal and comprising fins lib, and two superimposed pipes 18 extending to a length L between two end flanges 19a, 19b connectable respectively to header 10 and to a fume exhaust pipe not shown. Each pipe 18 has an inner surface 20 which comes into contact with the hot fumes; and pipes 18 are connected to each other by fins lib and by a diaphragm 21 perpendicular to fins lib. Exchanger 5 comprises turbulizers, each of which comprises a helical spring 22 inside a relative pipe 18 and substantially contacting inner face 20 of pipe 18, and a stopper 23 inside spring 22. Spring 22 and stopper 23 are located along a portion of each pipe 18 at flange 19b connected to the fume exhaust pipe not shown.

Heat exchanger 5 also comprises a fitting 24 extending perpendicularly to axis A and located between the two pipes 18 of exchanger 5, at flange 19b. Fitting 24 is formed in one piece with one-piece body 17, has a threaded end, is normally closed by a cap 25 screwed to the threaded end, communicates directly with pipes 18, and is connectable to a combustion fume analysis apparatus (not shown) .

In actual use, burner 4 feeds gas and air to combustion chamber 3, where the gas is ignited in known manner; and the combustion fumes are conveyed through outlet 13 and along header 10 to the two pipes 18 of heat exchanger 5, and are brought into contact with inner faces 20 of pipes 18 along the compulsory path defined by springs 22 and stoppers 23.

Using two pipes 18, as opposed to one larger pipe, has advantages both in terms of heat exchange, and by allowing greater freedom in the design of gas radiators, given the importance in this respect of reducing the size, in particular the depth, of exchanger 5.

The above advantages can be seen by comparing the heat exchange of a one-pipe and a two-pipe exchanger, with reference to the following heat exchange equation:

Q = K. A. V where :

Q is the amount of heat exchanged; K is a constant; A is the exchange surface; and V is the fume flow speed.

The comparison is made between an exchanger with one cylindrical pipe of radius R. and length L, and an exchanger with two cylindrical pipes of radius R₂ and length L. Assuming both exchangers have the same fume flow section πR_x ², the two pipes must have a radius of

The exchange surface A,, of the two pipes therefore equals 4πR₂L which is roughly 30% more than the heat exchange surface A_x of the single pipe, which equals 2πR-L. Since the fume flow section is the same in both cases, fume speed V will also be the same; and since constant K is also the same in both cases, it therefore follows that using two pipes as opposed to one enables a roughly 30% reduction in pipe radius alongside a roughly 30% increase in heat exchange efficiency.

Using three or more pipes obviously gives similar results.

Conversely, assuming the two pipes have the same exchange efficiency as the single pipe, the reduction in depth may be even higher than 30%.

Using two or more pipes as opposed to one provides for optimizing the size of the gas radiator as required in each case. That is, superimposing the pipes reduces the depth, whereas arranging the two pipes side by side reduces the height, of exchanger 5.

Claims

1) A gas radiator comprising a gas burner (4) ; a combustion chamber (3) having a casing (16) extending about an axis (A) ; and a fan (6) for directing a stream of air over the outside of said casing (16) and a heat exchanger (5) ; the gas radiator being characterized in that the heat exchanger (5) comprises at least two pipes (18) supplied in parallel with the fumes from the combustion chamber (3) .

2) A gas radiator as claimed in Claim 1, characterized in that said pipes (18) are superimposed.

3) A gas radiator as claimed in Claim 1 or 2, characterized in that the combustion chamber (3) has a flow section (S) crosswise to said axis (A) ; said flow section (S) being rectangular.

4) A gas radiator as claimed in Claim 3, characterized in that said axis (A) is substantially parallel to a horizontal first direction (Dl) ; the rectangular said flow section (S) having the long sides parallel to a vertical second direction (D2) .

5) A gas radiator as claimed in Claim 3 or 4, characterized in that said pipes (18) are parallel to the first direction (Dl) and aligned with each other and with the combustion chamber (3) in the second direction (D2) .

6) A gas radiator as claimed in Claim 3, 4 or 5, characterized in that said flow section (S) varies along said axis (A) . 7) A gas radiator as claimed in Claim 6, characterized in that said combustion chamber (3) comprises an inlet (12) and an outlet (13) ; said flow section (S) being minimum at the outlet (13) and maximum at the inlet (12) .

8) A gas radiator as claimed in Claim 7, characterized in that said casing (16) comprises two first walls (14) parallel to each other, and two inclined flat second walls (15) converging towards the outlet (13) .

9) A gas radiator as claimed in any one of the foregoing Claims, characterized in that said heat exchanger (5) and said combustion chamber (3) are the same length (L) along said axis (A) . 10) A gas radiator as claimed in any one of the foregoing Claims, characterized by comprising a header (10) connected to the combustion chamber (3) and to the heat exchanger (5) to feed the combustion fumes from the combustion chamber (3) to said pipes (18) . 11) A gas radiator as claimed in any one of the foregoing Claims, characterized in that the combustion chamber (3) and the heat exchanger (5) have respective fins (11a, lib) crosswise to said axis (A) .

12) A gas radiator as claimed in Claim 11, characterized in that said fins (11a, lib) are equally spaced with a given spacing (P) along said axis (A) .

13) A gas radiator as. claimed in Claim 12, characterized in that each fin (lib) of the heat exchanger (5) is aligned with a respective fin (11a) of the combustion chamber (3) .

14) A gas radiator as claimed in any one of the foregoing Claims, characterized in that said heat exchanger (5) comprises a one-piece body (17) made of metal and in which said pipes (18) are formed.

15) A gas radiator as claimed in Claim 14, characterized in that said one-piece body (17) comprises two flanges (19a, 19b) at opposite ends of said pipes (18) .

16) A gas radiator as claimed in Claim 14 or 15, characterized in that said one-piece body (17) is adjacent to the combustion chamber (3) .

17) A gas radiator as claimed in one of Claims 14 to 16, characterized in that said pipes (18) are connected to each other by a diaphragm (21) .

18) A gas radiator as claimed in one of the foregoing Claims, characterized in that said heat exchanger (5) comprises turbulizers (22, 23) inside said pipes (18) .

19) A gas radiator as claimed in Claim 18, characterized in that each turbulizer (22, 23) comprises a helical spring (22) adjacent to the inner face (20) of a respective pipe (18) ; and a stopper (23) inside the helical spring (22) .

20) A gas radiator as claimed in any one of the foregoing Claims, characterized in that said heat exchanger (5) comprises a fitting (24) communicating direction with said pipes (18) ; and a cap (25) for closing said fitting (24) .