ES2293752B1 - GAS CONVECTOR FOR DOMESTIC APPLICATIONS AND THEIR USE. - Google Patents

Abstract

Gas convector for domestic applications and their use. The described invention consists of a new convector design for domestic applications. This mobile indoor domestic heating appliance is not connected to an evacuation duct. This equipment uses liquefied petroleum gases, a gas burner in its lower part, a draft system to be able to evacuate the hot gases by convection, outer casing, grilles and mounting structure of the different parts (see figure 1). Among the most novel aspects of this invention, two can be highlighted: the draft system designed to ingest the amount of air needed (see figure 2) and the geometry of the outlet grid of the device (see figure 5). The innovative product obtained has better benefits than those existing in the market, being a good solution for homes that do not have heating infrastructure, with the additional advantage of their independence from gas or electricity installations.

Description

Gas convector for domestic applications and its use.

Technical sector

Domestic sector in both cities and areas rural where heating is required, especially in those places where the necessary infrastructure does not exist. Convector gas uses a bottle of liquefied gas and allows to maintain a room at comfortable temperature, without the need to gas or electricity supply facilities.

State of the art

The heating of the houses can be done by different routes, among which we can mention: boilers for water heating, heat pumps and systems that They use electrical resistance.

The traditional "butane stoves" (with infrared burners) have been a good solution for homes that do not have infrastructure of heating, constituting a relatively low cost equipment and with the additional advantage of its independence from supply facilities (gas or electricity). The design of the existing equipment of this type has not been optimized neither from the aesthetic point of view nor in terms of its operation, as seen in the available models [1, 2].

Gas convectors have been developed thanks to the contributions of many companies and researchers. In 1957 Oatley [3] patented a device that allows the air to be heated with combustion gases by exchanging heat without mixing. The described apparatus has a metal outer box and a series of tubes that allow thermal exchange and also allow the room to be heated by direct radiation from the front wall.
rior.

David Grieg from United Gas Industries LTD in 1966 [4] proposes a series of improvements to the gas convector. Like the previous device, the idea is to transfer heat of combustion gases into the air, in this case through a much more elaborate exchanger.

A year later Arnold and Watts de la Radiation LTD protect a radiant gas convector [5]. In this device, flue gases give up heat by radiation before mix with a certain amount of air and pass to the exchanger of heat This design makes it possible to improve the flow control of air that is required in the room to be heated.

Oatley with your company Oatley Technical Developments [6] in 1968 propose a series of improvements to the gas convector, incorporating radiation screens before heat exchanger that allows to heat the air with the gases of combustion

Also in 1968 Ryder de la Stoves LTD publishes a patent [7] related to gas convectors, specifically to achieve better heat transfer between the combustion gases and the air to be heated.

In 1973, United Gas Industries LTD patented a apparatus [8] for heating the air in gas convectors. He operating principle is to exchange heat between gases and the air without mixing them. A fan can be used to increase Air flow and gases can be obtained from a boiler.

In 1985 a patent was published that proposes substantial modifications to gas convectors existing. Tung and Niknejad of the British Gas corporation [9] patented a device that heats the room by convection and radiation passing the flue gases inside the tubes and The air outside. They have a condensate extraction system and They achieve high thermal efficiencies.

Chesworth of the company Willey Robinson LTD [10] patents a gas convector with very small dimensions for its caravan employment in 1986.

Jean and Jean Calude Carra in 1988 register a patent [11] on a transportable gas convector to heat kitchens, basements, greenhouses, etc. Owns a bottle of gas with a burner and an iron mesh outlet and achieves Distribute heat without blowers.

Goff and Goodey de la Beaumont John L LTD [12] propose improvements to avoid possible obstructions in the gas convectors

In 1997 Hacohen de la Combustion Products Developmen [13] propose a gas convector that allows heating a greater amount of air with combustion gases.

Most of the devices described in the preceding paragraphs transfer the heat of the gases from air combustion, that is, employment as a fluid is not valued air mixing heater with the products of the combustion, except the work of the French Carra. These equipment usually has low thermal efficiencies and some of them require blowing devices to move the air by heat exchangers.

The apparatus described in the present invention achieves high efficiencies by mixing the combustion products with the air in adequate proportions to achieve comfortable temperatures and minimum levels of environmental pollution, as was verified in the experiments performed. On the other hand, the draft system implemented allows the circulation and dispersion of the air-gas mixture in the room to be heated without the need for devices
auxiliary

Bibliography

1. Portable gas convector ( 2003 ), \ underline {http://www.rinnai.co.nz/convector\_heaters.htm}

2. Convection heater ( 2003 ), \ underline {http://www.altocity.com/browse/line\_3486.asp}

3. Oatley , AF ( 1957 ), Improvements relating to space heaters. Patent number GB779454

4. Grieg , D. ( 1966 ), Improvements in gas convector fires and the like. Patent number GB1028701

5. Arnold , JF and Watts , H. ( 1967 ), Radiant / convector gas fire. Patent number GB1065011

6. Oatley , AF ( 1968 ), Improvements relating to gas fires. Patent number GB1097232

7. Ryder , SEA ( 1968 ), Improvements in and relating to convector gas fires. Patent number GB1126957

8. United Gas Industries LTD ( 1973 ), Space heating appliance. Patent number GB1317566

9. Tung M. and Niknejad , J. ( 1985 ), Gas-fired convector or convector / radiant room heating appliance. Patent number US4531508

10. Chesworth , A. ( 1986 ), Gas-fired heating appliance. Patent number GB2165940

11. Carra , JC and Carra , J. ( 1988 ), Convector having several uses. Patent number FR2610393

12. Goff , PF and Goodey , CJ ( 1989 ), Convection space heating arrangement for a flame effect gas fire. Patent number GB2213577

13. Hacohen , J. ( 1997 ), Convector box gas fires. Patent number GB1342439 .

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Description of the invention Brief Description of the Invention

The patent convector is a mobile indoor domestic heating apparatus that is not connected to an evacuation duct. This equipment uses the energy produced by the combustion of liquefied petroleum gases ( LPG ) so it has a built-in gas bottle, a burner in its lower part and a draft system to evacuate hot gases by convection.

The gas bottle and the burner that make up the convector are commercial equipment that does not require a detailed description in this section. The changes object of patent has been made in the draft system and in the grid of team exit.

The shooting system is composed of two pieces independent called stages, located one inside the other. The first stage is located vertically above of the burner The second stage involves the first and has a greater height to favor the shot.

The entry of stages 1 and 2 in its part close to the burner must have an aerodynamic configuration to pass from a larger cross section at the entrance itself to a minor in a higher area.

The burner outlet and the entrance of the first stage must have a certain separation just like between the first and the second stage in order to favor the air intake

The highest possible height was sought in the design between the burner outlet and the stage 2 outlet, attending to the general design of the convector, to increase the available shot and air suction. Stage 2 has several front slots that Increase air intake and improve its operation.

The other important aspect of this invention is the grid, whose shape, material and location in the window of output have a considerable impact on its temperature.

With a grid thickness between 2 and 6 mm, width between 15 and 20 mm and number of plates between 5 and 12, located from parallel to the smaller dimension of the exit window (that is transversal to the exit window) the highest values are achieved suitable in its surface temperature.

Grids with two sections, one inside with thinner plates located at a certain separation from the Stage 2 and another exterior with thicker plates and with "V" shaped baffles have reduced the maximum temperature of the outer grid at perfectly admissible for domestic uses.

The grilles must be manufactured with a material of high thermal conductivity to promote exchange thermal.

Brief description of the content of the figures

Figure 1.- General plan of the convector , where the housing (1), structure (2), gas bottle (3), grilles (4), burner (5), Stage 1 (6) and Stage 2 (7).

Figure 2.- Shot system as a whole showing the solidarity location of the burner (1) and the two Stages (2 and 3).

Figure 3.- Side and isometric view of Stage 1 showing the aerodynamic geometry and the dimensions of the E1PZ3 variant.

Figure 4.- Side and isometric view of Stage 2 showing the geometry, dimensions and front grooves of the variant called E2PZ7.

Figure 5.- Plan of the grids showing the dimensions of the variant called Grid 3.

Detailed description of the invention

The present invention is based on the fact that inventors have observed that the efficiency of gas convectors, while decreasing gas, grid and housing outlet temperatures of the convector, through an improved design presented in this patent.

The object of the present invention constitutes it The improved gas convector. It is characterized by being constituted by a gas burner, a firing system formed by the solidarity set of two pieces called Stage 1 and Stage 2 that allow to ingest the necessary air, a grid located in the exit window, a gas bottle, a burner, a housing exterior and mounting structure of the different parts of the convector (see Figure 1).

The shooting system consists of the supportive adjustment of three elements consisting of the burner, one piece called Stage 1 and another called Stage 2 (see Figure 2). With this type of assembly improves air intake in the installation because:

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both of them elements are located in such a way that the losses of system pressure be minimal,

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 the Stage 2 has at least one front slot where it can enter certain amount of additional air to the system (see Figure 4),

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the Stage 2 has an aerodynamic geometry in the form of a nozzle convergent - divergent or only divergent, with the area of greater flow in the discharge than in the suction (see Figure 4),

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the Stage 1 has a larger flow area at the entrance than at the exit and the change of section from the entrance to the exit follows the streamline of streamlines (see Figure 3),

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the Stage 1 has a height lower than Stage 2 (see Figure 2),

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he burner, Stage 1 and 2 are located in that order according to the vertical direction conforming with its height a system of natural shot (see Figure 1).

The novel geometric configuration of the system shooting achieves a pressure reduction capable of ingesting a greater amount of air, allowing to cool the walls and equipment rack, as well as keeping the hot air in comfortable temperatures.

During the design and assembly, the firing system It is located at the top of the burner and its discharge is protected with a metal grid (see Figures 1).

The metal grid receives the heat of the gases Exhaust from the convector, so it heats up. The reduction of temperature is achieved through the release of heat to the medium environment, whereby the geometry, material and location of the grid in the exit window is of the utmost importance.

The grilles subject to protection here Patent for use in improved gas convectors are simple or doubles, they are manufactured with high thermal conductivity materials and are located transversely to the length of the section of exit and with its greatest thickness in the direction of movement of gases, all this to favor its cooling.

The operation of the entire system is simple, Liquefied gas from the bottle is taken to the burner where it is ignited by means of an ignitor, using as oxidant the atmospheric air, combustion products because of their high temperature rise through the system of shots formed by the stages 1 and 2, creating a vacuum that is occupied by outside air ingested that binds with the hot gases forming a mixture to lower temperature and with minimum carbon dioxide contents. These gases leave the convector through the exit window which is covered with a protection grid.

Stage 1 (see Figure 3) has a length equal to that of the burner plus 20 mm. The dimensions of this piece They are as follows: their height can range from 100 mm to the height of Stage 2 minus 100 mm, the width of the bottom It is located in a range of 80 - 100 mm, and at the top between 40 and 60 mm To reduce the flow area an angle of inclination in relation to the vertical that can go from 20º to 50th.

Stage 2 (see Figure 4) has a length equal to that of Stage 1 plus 35 mm and a height equal to that of the outer casing of the convector minus 40 mm. The other dimensions of  This piece are as follows: the width of the bottom is located in a range of 95 - 150 mm, and in the upper part between 120 and 200 mm. To reduce the flow area at the bottom you employs an angle of inclination relative to the vertical that can go from 0º to 50º, on one or both sides. On top the diffuser can be formed with an angle of inclination in the front wall and another on the back wall that may be the same or not and oscillate in the range of 2º to 10º.

Another aspect to highlight in Stage 2 are the longitudinal grooves on the front wall and on the walls lateral. The number of slots can range from 0 to 8 with dimensions 10 mm high and a length equal to the width of the wall less 30 mm Its location goes from the top to the bottom and it They are separated by a distance of 20 mm.

The vertical separation between the burner and the Stage 1 goes from -50 to 70 mm, indicating with the negative values the positions in which the burner is introduced within the stage and the positive values to the separation between both. The separation between Stage 1 and 2 ranges from -20 to 100 mm, with a meaning similar to explained in the preceding paragraph.

Another particular object of this patent is constitutes the exit grid with double section of plates and interleaved flow baffles.

The two sections of the grid are located in crosswise to the gas flow and the length of the gas itself window and each of them can be made up of 5 to 20 plates

The plates should be placed with their smallest thickness (between 1 and 5 mm) in the direction of the gas flow. Thicker in the direction parallel to the current is between 5 and 40 millimeters

Between both sets of plates are located "V" shaped diffusers to force the lines of gas flow stream to pass between the grid plates higher. A diffuser must be placed under each plate of the upper grid and the angle of the "V" can go from 2º until 10º.

The separation between Stage 2 and the first game of plates, between these and the diffusers and finally between diffusers and the upper plates is in all cases between 0 and 20 mm

Finally, it should be noted that the construction characteristics of the convector of the present invention allow a remarkably simple manufacturing process to be adopted, which affects the reduction of its construction costs.
tion.

Example of embodiment of the object of the invention Example 1 Gas convector for domestic use

The example described below does not It should be understood only as a limitation of the convector range of the present invention. On the contrary, the present invention try to cover all alternatives, variants, modifications and equivalences that can be included within the spirit and scope of the object of the invention.

The requirement of departure for the design of the convector is to achieve adequate equipment efficiency with comfortable air temperatures at the outlet and with temperatures in the housing and outlet grid below the values permissible for security.

The fuel used in the experiments was commercial butane, although propane can also be used. The reason stoichiometric air-fuel for butane is 15.5 kg_ {air} / kg_ {butane}. This gaseous fuel has a specific heat of combustion or calorific value exceeding 49 511 kJ / kg (118 738 kJ / nm 3), while its calorific value lower (with water vapor in gaseous state) is 45 771 kJ / kg (109 694 kJ / nm 3).

The study and characterization of the prototype initial of the convector, as well as its variants and modifications it is achieved by making measurements in each of the sets designed. Two types of main experiments are executed. In the called meshing experiments determine the parameters in each point of a very fine imaginary mesh in the section Transverse output of each stage analyzed. The experiments denominated global quantify the average parameters in the zone after homogenization, using an installation specifically built to achieve atmospheric pressure at team exit.

In the meshing experiments samples are taken of gas at the exit of each stage of the convector (burner, stage 1 and 2) in a very fine mesh, which is related with the area of each of the cross sections investigated At each sampling point the temperature is recorded and the volumetric composition of the gas (CO, CO2 and O2), using these components to quantify excess air existing in the gases. CO is also used to verify that its value is below the maximum limits allowed by the normative. In these experiments you can also measure the surface temperature of various types of plates and grilles with various forms of location on the output section of the gases

In global experiments they are added to measures mentioned in the previous paragraph two systems of instrumentation to measure the velocity or flow of the gas mixture air at the outlet of the convector. In these experiments the excess of air is determined by four ways; with CO measurements, O 2 and CO 2 in the gas-air mixture and with the determined flow through a pitot tube and a plate orifice. The final value is obtained by averaging the four values obtained and determining its standard deviation. The cases in which the differences obtained between the four methods are Significant scorn, repeating the essay.

One of the combinations tested was the called E1PZ3 + E2PZ7 + Slots (not shown in the figures) + Grid 3. The symbology used is the following E refers to stage and can be 1 or 2, PZ is the piece tested according to its geometry The word slots refers to the number of slots existing in stage 2 and finally the grid number is refers to different geometries analyzed.

Figures 3, 4 and 5 show the main dimensions of Stage 1, 2 and grid 3 respectively.

The results obtained in the experiments are the following: an excess of air of 36.65, with a temperature average of the gas of 82ºC and in the grid of 91ºC.

Claims (20)

1. High efficiency gas convector for domestic heating characterized by being constituted by a bottle of liquefied gas, a burner, a draft system formed by the two-piece solidarity assembly called Stage 1 and Stage 2 that allow the necessary air to be ingested , a grid located in the exit window, an outer shell and the mounting structure of the different parts. 2. Gas convector for domestic applications according to claim 1, characterized by a draft system is constituted by the integral adjustment of three elements consisting of a gas burner, an interior part called Stage 1 and an exterior called Stage 2 (see Figure 2), which enable the aerodynamic circulation of combustion gases and produce the necessary draft to ingest the amount of air needed in the system. 3. Convector gas for domestic applications a shooting system according to claim 2, characterized by Step 2 having an aerodynamic shaped geometry convergent-divergent nozzle or only divergent with larger flow area in the discharge in suction (see Figure 4). 4. Gas convector for domestic applications with a draft system according to claim 2, characterized by Stage 2 having a length equal to that of Stage 1 plus 35 mm and a height equal to that of the outer casing of the convector less 40 mm The other dimensions of this piece are the following: the width or depth of the lower part is located in a range of 95 - 150 mm, and in the upper part between 120 and 200 mm. To reduce the flow area at the bottom of this stage, an inclination angle is used in relation to the vertical which can range from 0º to 50º, on one or both sides of the piece. In the upper part, the diffuser can be formed with an angle of inclination in the front wall and another in the rear wall that can be the same or not and oscillate in the range of
2nd to 10th. 5. Gas convector for domestic applications with a draft system according to claim 2, characterized by Stage 2 having longitudinal grooves in the front wall and in the side walls. The number of slots can range from 0 to 8 with dimensions of 10 mm in height and a length equal to the width of the wall minus 30 mm. Their location goes from the top to the bottom and they are separated by a distance of 20 mm. 6. Gas convector for domestic applications with a draft system according to claim 2, characterized by Stage 1 which has a greater flow area at the entrance than at the exit and the change of section from the entrance to the exit follows the Streamline streamlines (see Figure 3). 7. Gas convector for domestic applications with a draft system according to claim 2, characterized by Stage 1 having a length equal to that of the burner plus 20 mm. The dimensions of this piece are as follows: its height can range from 100 mm to the height of Stage 2 minus 100 mm, the width of the lower part is in a range of 80 - 100 mm, and in the upper part between 40 and 60 mm To reduce the flow area, an inclination angle is used in relation to the vertical which can range from 20º to 50º. 8. Gas convector for domestic applications with a firing system according to claim 2, wherein Stage 1 and the 2 are located in that order according to the address vertical and according to the assembly from the inside to the outside (see Fig. 2). 9. Gas convector for domestic applications with a draft system according to claim 2, characterized by a vertical separation between the burner and Stage 1 between -50 and 70 mm, with the negative values indicating the positions in which the burner It is introduced within the stage and the positive values to the separation between both. The separation between Stage 1 and 2 ranges from -20 to 100 mm, with a meaning for negative values similar to that explained in the preceding paragraph. 10. Gas convector for domestic applications with draft system according to claim 2, with a geometric configuration that achieves a pressure reduction such that the amount of air ingested is increased, which allows cooling the walls and the grid of the equipment, as well how to keep hot air in temperatures
comfortable. 11. Gas convector for domestic applications according to claim 1, with a design and assembly such that the firing system is located at the top of the burner and its discharge is protected with a metal grid (see Figure 1). 12. Gas convector for domestic applications according to claim 1, characterized by placing in the outlet window a grid with single or double section of plates and with or without intercalated flow deflectors. 13. Gas convector for domestic applications according to claim 12, characterized by the grilles, which can be single or double and are manufactured with materials of high thermal conductivity being located transversely to the length of the outlet section and with its greater thickness in the sense of circulation of the gases, all this to favor its cooling. 14. Gas convector for domestic applications according to claim 12, characterized by the grilles that are located transversely to the gas flow and the length of the window itself and each of them can be formed from 5 to 20 plates. 15. Gas convector for domestic applications according to claim 14, characterized by the grid plates that must be placed with their smallest thickness (between 1 and 5 mm) in the direction of the gas flow. The greatest thickness in the direction parallel to the current is between 5 and 40 millimeters. 16. Gas convector for domestic applications according to claim 12, characterized in that the grid is formed by one or two plate systems to which or not V-shaped flow diffusers are placed. 17. Gas convector for domestic applications according to claim 16, characterized by the "V" shaped diffusers located under each plate of the upper grid and the "V" angle can range from 2 ° to 10 °. 18. Gas convector for domestic applications according to claim 1, characterized in that the separation between Stage 2 and the first set of plates, between these and the diffusers and finally between the diffusers and the upper plates is in all cases between 0 and 20 mm. 19. Use of a gas convector according to a any of claims 1 to 18 for heating of premises belonging, among others, to the following groups: a) Domestic facilities b) Social facilities c) Agricultural facilities. 20. Gas convector according to claim 1 whose parts can be constructed of stainless steel, brass, cast iron, any type of plastic, etc., which, depending of the applications cited in claim 19, resist the abrasion, corrosion and gas temperature.