FR3057650A1 - FLUID MASS STOVE - Google Patents

Abstract

- Heating device called "fluid mass stove", bringing together the advantages of the different types of existing stoves, but without their respective disadvantages. It heats up faster than conventional storage stoves because it allows convection and non-conduction accumulation and transport of calories. - It is characterized by a sealed box (6) connected to a fireplace (5) and containing a material with a high heat capacity suitable for convection (a fluid). A flue gas duct (7) pierces the box (6) from bottom to top and allows the gas to heat the assembly before their final evacuation. - The device presented in steel is particularly intended for heating homes, because in addition to its energy efficiency and comfort, it is transportable and inexpensive.

Description

DESCRIPTION

The present invention applies to the field of domestic heating without excluding the areas of collective and industrial heating. It relates to a device which combines the advantages of conventional heating principles (stoves, radiators) with those of storage stoves (commonly called "mass stoves").

Central heating was a great success from the sixties. The principle, - to heat and circulate a heat transfer fluid in a circuit of closed heating elements -, is simple, but, at the high cost of its installation and its maintenance is added today the dearness of fuels.

Today, the traditional wood stove is again arousing the interest of the French. The constructive and conductive material of traditional stoves is a ferrous metal (iron, cast iron, steel ...) and the thermal conductivity of these materials is excellent. However, these devices raise two problems:

- Traditional stoves require continuous fire and permanent care. Their fuel consumption (wood or wood derivatives) is substantial and makes the firewood industry flourish. However, it is obvious that the price of firewood will increase considerably in the coming years, which will make this type of heating much more expensive.

- The traditional wood heating methods (stoves, inserts, hot air recovery chimneys, pellet stoves, etc.) work mainly by convection: the air around the appliance heats, rises and disperses in the piece in a circular fashion. This causes the air to dry out and the dust circulation, which is said to be bad for the respiratory tract.

Mass stoves do not have these drawbacks. Their benefits are known: gentle and healthy heat, little air drying and limited dust circulation. Added to this is reduced consumption and good combustion. Their operating principles have been patented in America (US 4 406 276 A, Haas Théo, 27 Sept 1983) and in France (FR 641 642 A 7 August 1928, FR 2 522 784 Al, Bekas Frédéric, 9 September 1983).

- However, these mass stoves have drawbacks: their weight, their volume and their high price. These prices are due to the materials: the stone with high calorific capacity (soapstone, basalt etc ...) is heavy, difficult to transport and work.

The installation turns the home into a building site and once installed, these bulky devices become unmovable. Other disadvantages: the often limited dimensions of the hearth and the considerable time taken by the stove to begin to diffuse the heat.

However, the main storage material of the “fluid mass stove” is water. The stove can therefore be transported "empty", after which it is sufficient to fill it with ordinary water for the appliance to be operational. Besides being available and inexpensive,

-2 water has a volume thermal capacity which is at least 40% higher than that of refractory stone.

The principle of the fluid mass stove is simple: a hearth is connected to a conductive body which contains a fluid or other material with high calorific capacity.

This material will absorb the calories from the hot gases in the duct and transport them to the outer walls of the container where they will be diffused into the room by radiation. The container, we will call it "box". This box constitutes in itself a happy combination of 4 modes of heat transmission: transmission by conduction (first by the wall of the pipe and second by the wall of the box), transmission by accumulation, transmission by convection and radiation transmission. This specificity allows it to simultaneously fulfill 5 functions:

1) Transport the burnt gases to the exhaust pipe.

2) Contain a large quantity of materials with high calorific capacity.

3) Absorb the calories from the burnt gases it carries.

4) Transport these calories to the outside walls.

5) Diffuse (by radiation) these calories in the atmosphere.

These functions are also found in storage stoves (also called mass stoves), but they all have in common that the transport of calories is considerably hampered by the inertia of the materials of which they are made (stone, concrete, brick, etc. ...).

The difference is that here the inertia happens through a fluid. This has the consequence that the accumulation and transport of calories are optimized, since they are done by convection and no longer by conduction.

If it is desired to heat other rooms, it is possible to connect to the box a circuit of radiant elements, equipped with a circulator in order to propel the heat transfer fluid. This addition will transform the device into a “mass fluid boiler”.

The accompanying drawings illustrate the invention:

- Figure 1 shows an example of a powerful model.

- Figure 2 shows an example of a lower power model.

- Figure 3 shows a front section of the box with indication of the movement of the liquid.

- Figure 4 shows a side section of the device with number of elements.

- Figure 5 shows a variant with "straight flap or fin duct" (a straight variant is easier to produce) with indication of the convective movement of the fluid and image of the duct in perspective.

- Figure 6 shows a variant with "conduit straight to the Archimedes screw".

- Figure 7 shows a variant with "straight pipe with washers" with image of the pipe in perspective. Referring to drawings 1, 3 and 4, the heater presented highlights the remarkable capacities of two materials:

- for ferrous metal conductivity, rigidity and ability to radiation,

- for water, the volume thermal capacity and the capacity for convection.

By simultaneously exploiting the accumulation and heat exchange processes, this device provides comfort with exceptional energy efficiency. It reduces the heating work and the amount of the fuel bill.

We will call this model “fluid mass stove”.

It has a large closed, semi-closed or open hearth. Its mantle, like most parts of the device, is made of steel or stainless steel. This covering is part of the "box" (7) The interior of the hearth is made of cast iron dressed with vermiculite plates (20) to increase the temperature in the hearth. The hearth is connected to a spiral tube also made of steel or stainless steel (6) which will conduct the combustion gases coming from the hearth and allow them to mount in an oblique and circular fashion in an extended circuit. This spiral is built by an assembly of welded elbows. For consolidation, it is connected by steel rods (5) to the walls of the box. The spiral is an integral part of the box. It “pierces” it in order to prolong the time of circulation of the gases in the mass and can be equipped with a closing device.

Welded to the box from the bottom, it comes out freely at the top, coated with a fiberglass felt seal.

The box is superimposed or not on the hearth (which it partially wraps so that the whole takes on the appearance of a mass stove). It comprises a container, a cylinder, or any container and is connected to a gas evacuation pipe.

It can function as an independent heat source, but can also be connected:

- or to other heating elements provided that its material with a high calorific capacity is a fluid which directly feeds the heating elements or which transports its calories to a heat exchanger.

- or to thermal solar panels.

- either to a geothermal, aquathermic or aerothermal heat pump, which allows the box to also access the function of cooling or air conditioning element.

The box is waterproof (except at the top) and its walls are smooth or ribbed or worked so as to enlarge its exchange surface in order to increase the diffusion of heat in the atmosphere. It houses a vacuum (2) which serves as an expansion vessel for the liquid when the latter increases in temperature. The volume of this vacuum is determined by the location of an overflow valve or valve.

The box is equipped with filling and emptying openings allowing the tank to be filled with fluid as soon as the stove is put in place, and to be emptied again if it is necessary to transport it

-4The air enters through a mouth connected to the outside air and is preheated behind the hearth (15). The hot gases follow in the form of a spiral which allows the combustion gas to heat the mass it pierces as well as possible, consisting of steel and especially water. As of the first heat, a movement of convection of the fluid (figure 2) will contribute to the speed of heating of the mass and therefore of the part. The radiation, healthy and pleasant heat specific to mass stoves, is for the most part deferred but for a small direct part: thanks to the panoramic glass hearth, the user will benefit from a direct and immediate distribution of calories: that of the radiation of the fire and embers. By comparing the activity of the fireplace with the indication of the front thermometer, integrated into the box (17), we can deduce the fuel requirements: dry wood (branches, logs, reclaimed wood, pine cones, wood derivatives, etc.). ...).

The hearth can be adapted for natural gas, coal, waste derivatives, fuel oil or mixed combustion.

It is possible to connect the box to a heat pump for additional calorific contributions. It is also possible to connect the box to a heat exchanger or to a hydraulic network of heating elements (radiators, integrated circuits) and thus heat additional rooms.

Due to the simultaneity of the different heat transfer processes, the stove will heat up faster than conventional mass stoves. At the same time, it will stay hot for a very long time thanks to the exceptional heat storage coefficient of water.

Once the water exceeds a certain temperature (for example 70 ° C), a draft regulator will begin to reduce the air supply using a valve (14), to close it completely at, for example 95 ° C, this to avoid boiling of the fluid.

The valve (or other device located at the connection to the outside air of the hearth) is connected by a chain or rod (9) to a mechanical (or electric) draft regulator (8) whose thermal (or electronic) probe is located inside the box.

It can reopen automatically as soon as the fluid temperature drops.

This closing device of the air supply channel therefore makes it possible to regulate the temperature of the box by thermostatic means, electronically or else manually. A safety valve on the drain circuit (10) excludes the risk of overpressure in the event that, by mistake, the gasket or the valve at the top of the body becomes clogged.

The efficiency of this stove is such that 2 combustion sessions of about 1 hour are enough to heat a room of 100 cubic meters.

It may be desirable to slow the rate of calorie accumulation when the size of the chimney or room to be heated is reduced. In this case it is advised that the sealed conduit is in the form of a straight tube.

It can be equipped:

- either "strips" (FIG. 5), so as to increase the conductivity coefficient of this conduit while keeping a rather high rate of accumulation,

-5- either of an “Archimedes screw” (FIG. 6), so as to obtain a limited accumulation speed,

- or "washers" (Figure 7), so as to further reduce the rate of calorie accumulation.

In order to reduce production costs, we can opt for a tight conduit in bare straight tube. In this case, the drop in energy efficiency can be offset by a slight increase in the volume of the box.

SOME FIGURES IN COMPARISON:

- Volumetric thermal capacity (in kilojoule per cubic meter in Kelvin degree) massive volcanic stone: 2500 kJ / m ^3. ° K concrete dry earth steel air water

2250

1350

4130

1.25

4200

- Thermal conductivity (in Watt per meter in Kelvin degree) concrete water steel

1.20 w / m. ° K 0.60

- The increase in water temperature can cause a maximum volume expansion of 4%.

NUMBERING CONCERNING FIGURE 4 (in italics: optional accessories)

1 gas outlet 12 Drain pipe 2 expansion vacuum with tap 13 filling valve 3 manual draft shutter 14 air inlet valve 4 circulator outdoor circuit 15 vortex gas circuit 5 reinforcing rods 16 ash pan drawer 6 welded pipe (here in a spiral) 17 thermometer and logo 7 box (containing a fluid) 18 foyer door 8 draft regulators 19 access door 9 chain to valve 20 refractory panels 10 safety valve 21 return to external circuit 11 drain valve 22 artificial draw

Claims (7)

1) Conductive body, also acting as a heating body, called a "box" comprising a container, a cylinder or any container which may contain a fluid with caloric capacity above 4000 KJ /m3.°K. The box (FIG. 4, reference 7) is characterized in that it is pierced by a sealed duct (6) intended for the transport of combustion gases coming from a hearth. The filled box (7) is used simultaneously: - first to accumulate the calories contained in the combustion gases, - then, to transport these calories to the external walls, - and finally, to diffuse them into the air ambient by soft radiation. These three functions are found in conventional storage stoves (also called mass stoves), but these all have in common that the transport of calories is considerably hampered by the inertia of the materials from which they are made. The difference is that here the inertia happens through a fluid. This has the consequence that the accumulation and transport of calories are optimized, since they are done by convection and no longer by conduction. The duct can be extended to increase the heat exchange surface (Figure 3) or fitted with metal extensions to increase the transport of calories by conduction (Figures 5, 6 and 7). The duct can be fitted with an artificial draft (Figure 4, reference 22) and a closing device (3). The walls of the box can be worked in order to enlarge its exchange surface in order to increase the diffusion of heat in the atmosphere. 2) In order to increase its services, the box can be connected: - or to other heating elements for direct supply of the elements. - either by transporting its calories to a heat exchanger. In order to preheat the fluid from its contents, the box can also be connected: - or to thermal solar panels. - either to an electric heat source, - either to a geothermal, aquathermic or aerothermal heat pump, which allows the box to also access the function of cooling and air conditioning element. 3) Accumulation stove, according to one of the preceding claims, characterized by a closed, semi-closed or open hearth. This stove is paired with a conductive body (box) having a vertical tight duct in the form of a spiral. The burnt gases rise obliquely and circularly in an extended circuit enveloped by a fluid. This fluid is contained in a box which: - fully envelops a perforated cavity located above which serves as an expansion vessel, and can contain the excess volume of the heated fluid, -7- partially surrounds the hearth so that the whole takes on the appearance of a conventional mass stove (Figure 3). 4) Accumulation stove, according to the preceding claim, characterized in that the material of the box and the envelope of the hearth is a metal, so that its empty weight (therefore without fluid with high caloric capacity) allows its transportability. The box is equipped with filling and emptying openings allowing the tank to be filled with fluid as soon as the stove is put in place, and to be emptied again if it needs to be transported (figure 4). 5) Accumulation stove according to the preceding claim characterized in that the sealed conduit is in the form of a straight tube in order to slow the speed of the accumulation of calories. This may be desirable when the size of the chimney or room to be heated is reduced. The straight tube duct can be fitted with: - either "strips" (FIG. 5), so as to increase the conductivity coefficient of this conduit while keeping a rather high rate of accumulation, - either with an "Archimedes screw" (Figure 6), so as to obtain a limited accumulation speed, - or "washers" (Figure 7), so as to further reduce the rate of calorie accumulation. In order to reduce production costs, we can opt for a tight conduit in bare straight tube. In this case, the drop in energy efficiency can be offset by a slight increase in the volume of the box. 6) Stove or heating element according to one of the preceding claims, the heat source of which is supplied by wood, wood derivatives, natural gas, coal, electricity or waste derivatives. 7) Accumulation stove (Figure 4) according to one of the preceding claims, characterized in that the box containing the material with high heat capacity contains a front thermometer (17) and / or a thermal or electronic probe. This probe is part of a regulating device (8) guiding a valve (14) or other device located at the connection to the outside air of the hearth. The valve gradually closes until it is completely closed when the mass heat fluid reaches the desired temperature and reopens automatically as soon as the temperature drops significantly. This closing device of the air supply channel makes it possible to regulate the temperature of the box by thermostatic means, or else electronically. 1/7