WO2016092316A1 - Appareil de combustion à rendement amélioré - Google Patents

Appareil de combustion à rendement amélioré Download PDF

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Publication number
WO2016092316A1
WO2016092316A1 PCT/GB2015/053788 GB2015053788W WO2016092316A1 WO 2016092316 A1 WO2016092316 A1 WO 2016092316A1 GB 2015053788 W GB2015053788 W GB 2015053788W WO 2016092316 A1 WO2016092316 A1 WO 2016092316A1
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WO
WIPO (PCT)
Prior art keywords
cavity
stove
flue
firebox
combustion
Prior art date
Application number
PCT/GB2015/053788
Other languages
English (en)
Inventor
Howard James PYM
Original Assignee
Xtralec Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Xtralec Ltd filed Critical Xtralec Ltd
Publication of WO2016092316A1 publication Critical patent/WO2016092316A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24B—DOMESTIC STOVES OR RANGES FOR SOLID FUELS; IMPLEMENTS FOR USE IN CONNECTION WITH STOVES OR RANGES
    • F24B5/00—Combustion-air or flue-gas circulation in or around stoves or ranges
    • F24B5/02—Combustion-air or flue-gas circulation in or around stoves or ranges in or around stoves
    • F24B5/021—Combustion-air or flue-gas circulation in or around stoves or ranges in or around stoves combustion-air circulation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24B—DOMESTIC STOVES OR RANGES FOR SOLID FUELS; IMPLEMENTS FOR USE IN CONNECTION WITH STOVES OR RANGES
    • F24B1/00—Stoves or ranges
    • F24B1/02—Closed stoves
    • F24B1/026—Closed stoves with several combustion zones
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23L—SUPPLYING AIR OR NON-COMBUSTIBLE LIQUIDS OR GASES TO COMBUSTION APPARATUS IN GENERAL ; VALVES OR DAMPERS SPECIALLY ADAPTED FOR CONTROLLING AIR SUPPLY OR DRAUGHT IN COMBUSTION APPARATUS; INDUCING DRAUGHT IN COMBUSTION APPARATUS; TOPS FOR CHIMNEYS OR VENTILATING SHAFTS; TERMINALS FOR FLUES
    • F23L11/00—Arrangements of valves or dampers after the fire
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24B—DOMESTIC STOVES OR RANGES FOR SOLID FUELS; IMPLEMENTS FOR USE IN CONNECTION WITH STOVES OR RANGES
    • F24B7/00—Stoves, ranges or flue-gas ducts, with additional provisions for convection heating 
    • F24B7/02—Stoves, ranges or flue-gas ducts, with additional provisions for convection heating  with external air ducts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24B—DOMESTIC STOVES OR RANGES FOR SOLID FUELS; IMPLEMENTS FOR USE IN CONNECTION WITH STOVES OR RANGES
    • F24B7/00—Stoves, ranges or flue-gas ducts, with additional provisions for convection heating 
    • F24B7/04—Stoves, ranges or flue-gas ducts, with additional provisions for convection heating  with internal air ducts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24B—DOMESTIC STOVES OR RANGES FOR SOLID FUELS; IMPLEMENTS FOR USE IN CONNECTION WITH STOVES OR RANGES
    • F24B9/00—Stoves, ranges or flue-gas ducts, with additional provisions for heating water 
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24B—DOMESTIC STOVES OR RANGES FOR SOLID FUELS; IMPLEMENTS FOR USE IN CONNECTION WITH STOVES OR RANGES
    • F24B9/00—Stoves, ranges or flue-gas ducts, with additional provisions for heating water 
    • F24B9/006—Stoves, ranges or flue-gas ducts, with additional provisions for heating water  flue-gas ducts
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24C—DOMESTIC STOVES OR RANGES ; DETAILS OF DOMESTIC STOVES OR RANGES, OF GENERAL APPLICATION
    • F24C13/00—Stoves or ranges with additional provisions for heating water
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
    • H10N10/10—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects operating with only the Peltier or Seebeck effects
    • H10N10/13—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects operating with only the Peltier or Seebeck effects characterised by the heat-exchanging means at the junction
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24B—DOMESTIC STOVES OR RANGES FOR SOLID FUELS; IMPLEMENTS FOR USE IN CONNECTION WITH STOVES OR RANGES
    • F24B5/00—Combustion-air or flue-gas circulation in or around stoves or ranges
    • F24B5/02—Combustion-air or flue-gas circulation in or around stoves or ranges in or around stoves
    • F24B5/021—Combustion-air or flue-gas circulation in or around stoves or ranges in or around stoves combustion-air circulation
    • F24B5/025—Supply of secondary air for completing combustion of fuel

Definitions

  • This invention relates to combustion apparatus with improved efficiency.
  • the present invention relates to combustion apparatus in which combustible materials are burned, and thereby provide heat as a primary source of energy, and which are further adapted so as to extract a greater amount of energy from the combustion and the combustion gases arising from it than merely the heat radiated from the combustion and from the combustion apparatus itself.
  • the invention relates to a combustion apparatus adapted to provide a source of electrical power by utilising thermoelectric generators (hereinafter "TEGs"), and in certain other embodiments, the present invention relates to combustion apparatus provided with so-called back- boilers which utilise the heat energy of the combustion apparatus and combustion occurring therein as a means of heating water, for use either in a closed radiator or central heating system, or more simply in a hot water supply system.
  • TOGs thermoelectric generators
  • the term “stoves” shall be used to cover all manner of combustion apparatus, including incinerators, boilers, ovens, wood or other solid-fuel burning stoves, and indeed any combustion apparatus within which combustion occurs and which thus typically generate large amounts of heat energy.
  • thermal energy extraction means shall be used to cover both TEGs and back-boilers, as both are, in currently available stoves, mounted to or form part of either one of the stove walls or the flue to which the stove is connected and through which hot combustion gases therefrom are exhausted.
  • both TEGs and back-boilers (which are, in essence, heat exchangers) have a fundamental requirement for source of heat if either is to function at all.
  • a TEG is a device comprising a thermocouple junction that generates a voltage when the dissimilar metals of the junction are maintained at different temperatures.
  • a TEG comprises a main body portion having a "hot side", which is placed in contact with a heat source, and a "cold side", which is placed in contact with a heat sink. Exposure of the TEG to an elevated temperature on its hot side and a relatively lower temperature on its cold side results in the generation of an electrical voltage, which can be harnessed as a useful source of electrical power.
  • TEGs have been used for decades in a wide variety of applications ranging from satellites for generating power from solar energy, to more mundane applications, such as in barbeques: to provide a source of electrical power for grill fans and motors, for example, as described in US7198383, US2005034716 and US2002148458.
  • the basic principle of operation of the TEGs themselves is the same: namely the provision of a temperature difference across which the TEG is placed to produce an electrical power output.
  • This invention is particularly concerned with power generation in domestic or commercial environments, or in "off-grid” applications where access to mains electricity and gas supplies are not readily available.
  • a stove with a back boiler to provide both local heating and hot water and/or hot water for a central heating system.
  • Known back boilers comprise a fire box within which a combustible fuel is burned, and a water tank adjacent the fire box.
  • the tank and fire box share one or more sidewalls, e.g. the back wall of the fire box forms a front wall of the tank, such that, in use, heat within the fire box is conducted from the fire box, through the shared wall (which is typically made of a high conductivity, corrosion-resistant material, such as stainless steel) to heat water within the tank.
  • Back boiler systems of this type have been in existence for a long time, and they have been developed over the years to improve their efficiency and to provide a source of hot water for a central heating system.
  • a long-felt problem with known back boilers of the type comprising a tank comprising part of a heat exchanger for a set of central heating radiators is that, over time, the radiators' temperatures begins to fall.
  • the radiators are designed to dissipate heat efficiently, and so it is possible for the heat dissipation of the radiators to relatively quickly exceed the heat input into the hot water system via the back boiler.
  • the rate of heat dissipation from the radiators is a function of the radiator temperature and the temperature of the air surrounding the radiator, as the radiator temperatures increases relative to their surrounding air temperature (e.g. when the radiators are first used to heat a cold room), the rate of heat dissipation by the radiators is relatively high.
  • the nett effect is that the back boiler can draw excessive amounts of heat from the fire box.
  • the effect is further exacerbated by the fact that a relatively cool fire box is inefficient because combustion of the fuel is more efficient at higher temperatures.
  • the combustion efficiency drops, resulting in less heat input, greater cooling and so the cycle continues until an inefficient equilibrium has been reached, which is usually one with cooler than desirable radiators, and sub-optimal combustion conditions within the fire box.
  • a stove comprising a combustion vessel and a flue through which combustion gases are exhausted, said combustion vessel having one or more external walls, and a first internal dividing wall to an interior side of which is provided a firebox, and to an exterior side of which is provided a cavity defined between said dividing wall and at least one of said external walls, said firebox having a flue outlet in fluid communication with the flue and a valve for selectively opening and closing the flue outlet, and a supplementary vent aperture provided in said first dividing wall in fluid communication with the cavity which in turn is also provided with a flue outlet, characterised in that the supplementary vent aperture and the cavity flue outlet are provided towards first and second ends of the cavity respectively such that combustion gases are constrained to flow within the cavity from said first end toward said second end and are reheated to some degree as they do so by virtue of the adjacency of the cavity and the firebox, and further characterised in that thermal energy extraction means is secured to at least one wall of the cavity adjacent which there is some flow
  • the supplementary vent aperture and the cavity flue outlet are disposed at substantially opposite ends of the cavity, being the first end and second end thereof respectively.
  • the thermal energy extraction means is one of: a plurality of TEGs, and a back-boiler, or a heat exchanger portion thereof.
  • the cavity flue outlet is downstream of one or both of: the firebox flue outlet, and the firebox valve.
  • one or more further dividing walls disposed within the cavity which further constrain the flow of combustion gases within the cavity immediately after they enter through the supplementary vent aperture.
  • the combustion vessel may include a single further dividing wall extending from the top of the cavity to a point above the base of the cavity, the flue outlet of which may then be located at or towards the top of the cavity on an opposite side of the further dividing wall to the vent aperture.
  • the fire box suitably comprises a hollow receptacle for receiving the fuel, which may be a solid fuel, such as wood, coal, charcoal or briquettes.
  • the fire box is suitably manufactured of a durable, temperature-resistant material, such as steel or cast iron and may comprise an access aperture, such as a door, through which the fuel can be placed inside the fire box.
  • the fire box suitably comprises an air inlet aperture, which is suitably arranged to provide a curtain or "wash" of air as it enters the fire box to aid combustion of the fuel.
  • the air inlet aperture suitably comprises control means, such as a damper, flap closure, or a hit-and-miss valve arrangement that permits the volume and/or speed of the incoming air to be controlled. This suitably enables a user to control the burn rate of the fuel within the fire box.
  • the control means may be manually or computer-controlled, for example using an actuator operatively connected to a control system or circuit.
  • the flue outlets are in fluid communication with a flue stack, which creates a "draw" to facilitate burning the fuel within the fire box.
  • the valve is adapted, in use, to enable the firebox flue outlet to be selectively opened or closed.
  • the valve may comprise an on/off valve, whereby the firebox flue outlet is either fully-open or fully-closed, or it may permit partial opening of the firebox flue outlet.
  • a control system such as a manually-operated lever, or an actuator and a control circuit, may be used to control the actuation of the valve.
  • One or more temperature sensors may usefully be provided within the fire box to enable the opening and closing of the valve, and, where provided, the air inlet aperture control means, to be computer-controlled to optimise, in use, the combustion of fuel within the fire box.
  • the fire box suitably comprises a supplementary vent aperture located at, or towards, the top of the fire box.
  • a supplementary vent aperture located at, or towards, the top of the fire box.
  • flue gasses may be vented from the fire box via either the firebox flue outlet and/or via the supplementary vent aperture depending on the state of the valve, but that in the vast majority of cases, the flue gasses will follow "the path of least resistance" and will preferentially vent via the firebox flue outlet when the valve is open. In other situations, for example, where the valve is part-closed, the flue gasses may vent via various routes. This particular configuration enables the fire box to be used in a wholly conventional manner, i.e.
  • the adjacency of the firebox and the cavity result in those flue gases flowing through the cavity and being reheated to some extent by both radiation from the combustion occurring within the firebox, and radiative and conductive effects of the hot walls which define or are provided within the cavity.
  • the degree of reheat of course depends on the configuration of the cavity and firebox, but in any event the reheating effect will always represent an improvement in the overall efficiency of the stove as compared with any conventional stove in which all the flue gases from the combustion are vented practically immediately and upwardly from their source through the flue, and ultimately to air.
  • Such a configuration can afford the user a great many options and permits the user-selection of various modes of operation. Such a configuration also usefully enables a user to smoothly transition between various modes of operation, thereby reducing the likelihood of inadvertently snuffing the fire out, or causing undesirable flare-ups.
  • the cavity acts as a heat store because the flue gas enters the cavity, and can be kept warm by radiated heat from, or conducted heat through, the sidewall of the fire box.
  • the temperature of the flue gas within the cavity is regulated, that is to say, it reaches a certain temperature, which is substantially maintained.
  • the hot side of the thermal energy recovery means which are in contact with an exterior sidewall of the cavity are maintained at a substantially constant temperature.
  • the hot sides of the thermal heat energy recovery means are in contact with one of: an exterior wall of the combustion vessel, the exterior (that is, being most proximate the exterior wall of the combustion vessel) side of the internal dividing wall, an interior or exterior side of any further dividing wall which may be provided, or within the further dividing wall if said further dividing wall is hollow.
  • thermal energy extraction means comprise one or more of: a plurality of TEGs, and a back-boiler, or a heat-exchange portion thereof.
  • one or more catalytic converters may are provided in the cavity, suitably disposed between a pair of walls, said cavity walls being at least one of defining and dividing the cavity, and extending over substantially the entire width of the cavity such that most or all of the flue gases flowing through the cavity between said pair of walls is constrained to flow through the catalytic converter.
  • the stove may be provided with a secondary burning system wherein one or more additional air passageways is defined within the stove having one end which is open to the surrounding atmosphere, and which terminate at a blind end disposed in the upper reaches of the firebox, at least a portion of said one or more passageways being adjacent a vertical defining wall of the firebox such that ambient air drawn into the passageway is heated, and preferably superheated, by heat emanating from the combustion occurring in the firebox and the vertical defining wall thereof, a subsequent portion of said one or more passageways being substantially horizontal and terminating at said blind end, said passageway subsequent portion being provided with a series of exit ports which allow heated or superheated air to escape into the upper reaches of the firebox where a secondary combustion with flue gases can be caused to occur.
  • one or more additional air passageways is defined within the stove having one end which is open to the surrounding atmosphere, and which terminate at a blind end disposed in the upper reaches of the firebox, at least a portion of said one or more passageways being adjacent a vertical defining wall
  • the subsequent portion of said one or more passageways is disposed adjacent the supplementary vent aperture.
  • the aforementioned aspect of the invention is thus distinguished over known stoves by the provision of any one or more of the group comprising: the supplementary vent aperture; the cavity; the internal dividing wall; the one or more further dividing walls; the disposition of the supplementary vent aperture and cavity flue outlet as regards the length of the cavity; the cavity flue outlet being in fluid communication with the flue at a point downstream of the firebox flue outlet and/or valve therein; and the disposition of the thermal energy extraction means wherein their hot sides are in contact with either or both of the combustion vessel exterior wall and the one of the walls defining or provided within the cavity.
  • the in-rush of ambient air into the fire box effectively overcomes the draw of the flue, and so flue gas flow is temporarily halted.
  • the ambient air immediately cools the firebox side walls to which the thermal energy extraction means are affixed, thus stopping, or reducing, power generation until the fire box reaches its operating temperature again.
  • the stalling of the flue gasses merely serves to retain already pre-heated flue gasses within the cavity, thus permitting the thermal energy extraction means to continue generating useful output power, in spite of the fire box door being opened temporarily.
  • a further benefit of the provision of a cavity is a more even heating of the cavity's side walls with which the thermal energy extraction means' hot sides are in contact.
  • the cavity serves to more evenly distribute the heating of the wall to which the thermal energy extraction means are affixed, which means that a vertical and horizontal array of thermal energy extraction means can be used and in which, in the case of TEGs, all, or the vast majority of them generate substantially the same amount of electrical power.
  • the one or more further dividing walls within the cavity serve to constrain the flue gasses entering the cavity via the supplementary vent aperture into a downward direction of flow.
  • the flue gasses in the cavity between the internal dividing wall (one either side of which lie the fire box and cavity respectively) and the further dividing wall are kept hot by radiated and/or conducted heat through the internal dividing wall which separates the firebox and cavity such that the temperature of the flue gases is substantially maintained as they flow within that part of the cavity, and when they pass by the lower edge of the further dividing. Having passed-by the lower edge of the further dividing wall, the flue gasses then rise up through the cavity in the space between the further dividing wall and the plate to which the thermal energy extraction means are mounted.
  • the thermal energy extraction means each conduct some heat out of the flue gasses, but it will be noted that the flue gasses reach the lowermost thermal energy extraction means at their hottest and cool as they rise up through the cavity and heat the hot side of successive rows of the thermal energy extraction means. Contrast this with an arrangement omitting the further dividing wall, in which the hottest thermal energy extraction means would be at the top of the cavity and the coolest thermal energy extraction means at the bottom. In other words, the provision of the further dividing wall can serve to more evenly distribute the heat to all of the thermal energy extraction means in the array, thus avoiding "hot spots" and resulting in more even heat energy extraction.
  • the thermal energy extraction means are suitably arranged in an array of rows and columns.
  • the array of thermal energy extraction means is suitably provided on a heat exchange plate which may either form, or be attached to an exterior side wall of the combustion vessel.
  • the cool side of the thermal energy extraction means are suitably in contact with a cooling means.
  • the cooling means may comprise a water jacket in fluid communication with one or more radiators.
  • the "waste heat" is put to good use, say heating a building using the one or more radiators.
  • a fire box providing a primary heating source (cf. a wood stove, wood-burning oven, incinerator or the like), the thermal energy extraction means, which produce useful amounts of electrical power, and a secondary heating source, i.e. the radiator(s) all three of which are powered by a single fuel source, namely the fuel in the fire box.
  • a primary heating source cf. a wood stove, wood-burning oven, incinerator or the like
  • the thermal energy extraction means which produce useful amounts of electrical power
  • a secondary heating source i.e. the radiator(s) all three of which are powered by a single fuel source, namely the fuel in the fire box.
  • the duty cycle of TEGs at least can be greatly reduced if the temperature differential is too high, and that above a certain temperature differential, the TEGs power output rises no further (meaning that its efficiency tails off) and that its duty cycle drops off.
  • Figure 1 is a schematic cross-sectional view of a first known TEG-stove
  • Figure 2 is a schematic cross-sectional view of a second known TEG-stove
  • Figures 3 and 4 are schematic cross-sectional views of a first embodiment of a TEG-stove in accordance with the invention in a first and second mode of operation, respectively;
  • FIG. 5 is a schematic cross-section a second embodiment of a TEG-stove in accordance with the invention.
  • Figure 5A is shows the stove of Figure 5 in which one hollow dividing wall is water tank;
  • Figure 6 is a schematic perspective view of a third embodiment of a TEG-stove in accordance with the invention.
  • FIG. 7 is a schematic perspective view of a fourth embodiment of a TEG-stove in accordance with the invention.
  • Figure 8 is a schematic cross-section of a fifth embodiment of the invention.
  • Figure 9 is a schematic cross-section of an embodiment of a stove or oven in accordance with the invention.
  • Figure 10 is a schematic cross-section of the stove of Figure 3 including catalytic converters, and
  • Figure 11 is a schematic perspective illustration of one side of a firebox of a stove having a secondary burning system in accordance with the invention.
  • a first type of known TEG-stove 10 comprises a cast iron fire box 12 into which a solid fuel 14, such as wood, charcoal, coal or briquettes is placed, via an access hatch 15 in the form of a hinged door that opens directly into the fire box 12.
  • a solid fuel 14 such as wood, charcoal, coal or briquettes
  • the fuel 14 burns, and flue gasses 16 exit the fire box 12, via a flue outlet aperture 18 into a flue stack 20 in direct fluid communication with the fire box 12.
  • the flue gasses 16 are hot, and so the sidewalls of the flue stack 20 become hot, in use.
  • a set of TEGs 22 are bonded with their hot sides 24 in contact with the outside of the side walls of the flue stack 20 and with their cool sides 26 being cooled by passive (e.g. using a heat sink), or forced air cooling (e.g. using a fan).
  • passive e.g. using a heat sink
  • forced air cooling e.g. using a fan
  • the flue stack 20 is hottest where it meets the fire box 12 and cools progressively with distance from the fire box 12. This is indicated schematically in the graph accompanying Figure 1, which shows temperature T as a function of distance d from the fire box 12: the temperature profile being indicated by the solid line 28.
  • the power output P of the TEGs 22 is dependent on the relative temperatures of the TEGs' hot and cold sides, and the power output P is also plotted in the graph accompanying Figure 1 as a function of distance d from the fire box 12 by the chain-link line 30.
  • FIG 2 is a schematic of another known TEG-stove, and identical reference signs have been used to identify identical features to avoid repetition and for ease of understanding.
  • the known TEG- stove 10 of Figure 2 also has a fire box 12 in which fuel 14 is burned, with flue gasses 16 exiting the fire box 12 via a flue outlet aperture 18 into a flue 20.
  • the TEGs 22 are not affixed to the flue 20, but rather to the exterior of the side walls of the fire box 12.
  • a known stove with back-boiler is largely identical in configuration to the stove shown in Figure 2, excepting that the TEGs 22 are replaced with a heat exchanger with a heat exchange plate which forms a shared wall between the heat exchanger and the fire box 12.
  • the heat exchanger is filled with water, which is heated by radiated and conducted heat from the fire box 12 which may then be used to heat a set of radiators.
  • the upper portion 36 of the fire box 12 is relatively hot, and this is shown on the temperature profile graph accompanying Figure 2.
  • the TEGs 22 located towards the top of the fire box 12 are overheated, thus not producing any more power than their maximum, but suffering from overheating and thus a reduction in duty cycle.
  • the TEGs located lower down the side walls of the fire box 12 are under-heated, and thus do not produce maximum power.
  • this known system suffers from reduced duty cycle of the overheated TEGs 22 and reduced power output of the under-heated TEGs. This arrangement is also inherently inefficient.
  • a TEG-stove 100 in accordance with the invention comprises a fire box 102 inside which a quantity of fuel 14 is burned, in use.
  • the fire box 102 comprises a flue outlet aperture 104 through which flue gasses 106 escape into a flue 108.
  • the flue outlet aperture 104 is selectively openable and closable by a valve assembly 110, which is shown schematically as a flap valve.
  • the flap valve 110 is open so that flue gasses 106 leave the fire box 102 in a conventional manner.
  • the invention is characterised by the addition of a cavity 112 located externally of, but adjacent to and in fluid communication with, the fire box 102, and at least partially defined on its interior side by an internal dividing wall 113.
  • the fire box 102 has a supplementary vent aperture 114, in the form of a slotted aperture, at, or near to the upper edge of its sidewalls, which provides fluid communication between the fire box 102 and the interior of the cavity 112.
  • the cavity 112 in various embodiments, comprises a further dividing wall 116, which extends from the top of the cavity 112 to a point just above the base of the cavity 112, leaving a gap 118 (in this case a slotted aperture) such that flue gasses 106 (as shall be described below) can pass around the lower edge of the dividing wall 116 and rise up again on the opposite side of the dividing wall 116.
  • a gap 118 in this case a slotted aperture
  • the cavity 112 comprises an outlet aperture 120 (also a slotted aperture in this example), which communicates with the flue 108 at a point 122 above the valve 110.
  • TEGs 126 Mounted to an external side wall 124 of the cavity 112 is an array of TEGs 126 whose hot sides are in contact with the side wall 124 of the cavity 112, and whose cold sides are thermally coupled to a radiator system 128.
  • the array of TEGs 126 could equally be replaced with the heat exchanger of a back-boiler arrangement having a heat exchange plate which is secured to, or forms an integral part of, wall 124. In this and other corresponding arrangements, the cold side of the heat exchanger would be thermally coupled to a radiator system.
  • valve 110 In the configuration shown in Figure 3, with the valve 110 open, flue gasses 106 exit the fire box 102 directly via the outlet aperture 104 into the flue 108, and the TEGs 126 are relatively inactive. Once a fire within the fire box 103 has been established, the valve 110 can be closed to shut off the exit path of the flue gasses 106 directly into the flue 108, which is now heated and "drawing".
  • the flue gasses 106 now exit the fire box 102 via the supplementary vent aperture 114 and enter the cavity 112, where they are initially drawn downwards by the draw from the flue 108. Radiating heat 130 from the fire box 102 serves to maintain the temperature of the flue gasses 106 as they descend in the cavity 112, before they pass around the lower edge of the dividing wall 116 and are vented into the flue 108 via the outlet aperture 120 at a point 122 above the valve 110.
  • the temperature difference between the lower edge 124a of the side wall 124 and its upper edge 124b has been found to be as little as 5 degrees centigrade, which means that all of the TEGs' 126 hot sides are maintained at substantially the same temperature.
  • all of the TEGs generate substantially equal amounts of electrical power, as indicated by the chain-link line 134 in the graph accompanying Figure 4.
  • all of the TEGs 126 operate at maximum power generation, but without overheating or under-heating, as is the case with the known TEG-stoves 10 described above in relation to Figures 1 and 2.
  • the rate of cooling is not too aggressive, and by thermostatic control, the temperature of the radiators can be maintained at around 55 degrees centigrade, thus optimising the power output 134 of the TEGs 126.
  • the invention as shown in Figures 3 and 4 provides primary heating from burning the fuel 14, secondary heating from the radiator system 128 and a substantially constant electrical power output from the TEGs 126.
  • the temperature profile 132 of the cavity side wall 124 is substantially uniform across its entire area, the number of TEGs 126 can be readily increased, say by providing an array of TEGs 125 all of which will be operating at, or about, their maximum power outputs. This represents a substantial increase in the efficiency of a TEGs-stove 100 compared with known TEG-stoves 10.
  • the cavity 112 acts as a heat store, and traps heat in the flue gasses 106, even if the door (not shown) of the fire box 102 is temporarily opened, the temperature profile 132 of the cavity's side wall 124 is maintained for a sufficient period of time to avoid the power generation 134 of the TEGs 126 dropping off significantly, if at all.
  • an adaptation 200 of a TEG-stove 100 in accordance with the invention previously described comprises a hollow dividing wall 116.
  • Such a configuration enables further, additional TEGs 202 to be fitted to the TEG-stove, within the hollow interior 204 of the dividing wall.
  • the principle of operation of the TEG-stove shown schematically in Figure 5 of the drawings is the same as that described above in relation to the embodiment shown in Figures 3 and 4, so the operation of this embodiment need not be repeated herein for brevity and to avoid repetition. Nevertheless, it may be noted that some of the additional TEGs 202 are heated on the downward leg of the flue gas' route.
  • FIG 5A it can be seen that it is possible to use the hollow interior of dividing wall 116 as a water tank (the interior being shown hatched in Figure 5A to represent this), and this is particularly useful in embodiments of the invention incorporated back-boiler arrangements. It is to be noted in Figure 5A how combustion gases flow around both sides of the hollow dividing wall, and thus serve to heat the water therein on both sides - a much more efficient arrangement than simply providing a tank of hot water to one or other side of the stove.
  • an embodiment of a TEG-stove 400 in accordance with the invention comprises a fire box 102 having an internal dividing wall 402 whose upper edge comprises a slotted supplementary vent aperture 114 leading to a cavity 112 located externally of the fire box 102.
  • the flue gasses 106 first pass over the top of hollow dividing wall 116 before being drawn downwardly into the cavity by the draw of the flue 108.
  • the flue gasses then pass around the lower edge of the hollow dividing wall 116 before rising back up the cavity 112 to exit via the outlet 120 and to enter the flue at a point above the valve 110 as previously described.
  • the hollow dividing wall 116 contains two arrays of supplementary TEGs 404 whose hot sides are in contact with the interior side walls of the hollow diving wall 116, and are thus heated indirectly by the flue gasses.
  • the 120 comprises a set of elliptical cross-sectioned tubes 406 which are arranged so as not to significantly impede the in-flow of flue gasses 106 into the cavity 122 as the pass around the outsides of the tubes 406, and which have sufficiently large cross-sectional areas so as not to impede the flow of flue gasses 106 as they exit the cavity 112.
  • the tubes 406, in certain embodiments, are interconnected downstream by a manifold, before re-entering the flue 108 at a point downstream of the valve 110.
  • the configuration is significant for the reasons that shall be described below with reference to the graph accompanying Figure 6 of the drawings.
  • the flue gasses 106 enter the cavity via the supplementary vent aperture 114 at a temperature 410.
  • the temperature drops slightly, by a few degrees centigrade, as the flue gasses 106 descend in the cavity 112 to point 412.
  • the flue gasses 106 pass underneath the hollow dividing wall 116, they are re-heated now by radiating heat 130 from the side wall 402 of the fire box 102.
  • the temperature of the fire box's side wall 402 is higher at its upper edge than at its lower edge, so the amount of radiant heating within the cavity will be greater towards the top of the fire box 102 that towards the bottom of the fire box 102.
  • the relative amounts of radiant heat 130 is indicated by the size of arrows 130a, 130b and 130c.
  • the amount of radiant re-heating 130c is greatest where one would expect the flue gasses to have cooled the most, thus the radiant re-heating effect serves to maintain the temperature 132 of the flue gasses 106 within the cavity at a substantially constant temperature, and thus the power output 134 of the TEGs 126, 404 is substantially constant. This also leads to a great increase in efficiency compared with known TEG-stoves, such as those described in relation to Figures 1 and 2 above.
  • the cavity 122 can be extended down below the level of the base of the fire box 102, in certain embodiments, and this may be a useful way of increasing the number of TEGs 126, 404 used in the system.
  • the cavity extends down into a base or the legs of a TEG-stove in accordance with the invention.
  • a heat exchanger may be employed to heat a tank of water, for example, which could be located nearby or provided within the stove as illustrated in Figure 5A (see above). Such a configuration enables excess heat to be stored, rather than wasted.
  • FIG. 7 of the drawings A yet further embodiment of the invention 500 is shown in Figure 7 of the drawings in which the cavity 112 is formed as a shell 502 surrounding, and spaced-apart from, the fire box 102.
  • the dividing wall 116 previously described is formed by the exterior of the firebox 102, which serves to direct the flue gasses 106 downwardly from the supplementary vent aperture 114, around the base of the fire box, before rising again through the outlet 120 into the flue (not shown) at the back of the TEG-stove 500 at a point downstream of the valve (also not shown for clarity).
  • the embodiment shown in Figure 7 usefully enables the base 504, side walls 506 and rear wall 508 of the shell 500 to be provided with arrays of TEGs 126, thus maximising the electrical power output of the system. Further, because the dividing wall is the fire box itself, radiant re-heating of the flue gasses 106 occurs continuously, thus avoiding or reducing the hot side temperature drop of known TEG- stoves, which leads to under-performance of the TEGs.
  • the embodiment of the invention 600 shown in Figure 8 of the drawings comprises a fire box 102 as previously described, but this time, the cavity 122 is located above the fire box 102.
  • the cavity is defined by a series of staggered, hollow dividing walls 116 arranged above one another, but nevertheless being similar to the arrangement described above in relation to the embodiment shown in Figure 5.
  • each of the hollow dividing walls 116 comprising a hollow interior cavity 204 to whose inner side walls, arrays of supplementary TEGs 602 are affixed.
  • flue 106 gasses can exit the fire box 102 via the supplementary outlet aperture 144 and enter a serpentine pathway within the cavity 112 defined by the hollow dividing walls 116 before exiting via an outlet slotted aperture and into the flue at a point downstream of the valve 110.
  • This particular embodiment of the invention could be fitted to commercial and/or industrial boiler systems, such as those found in factories, commercial premises and the like to provide a locally-generated source of electrical power.
  • the embodiment of the invention shown in Figure 9 of the drawings is a stove/oven 700 comprising a fire box 102, a cavity etc. as previously described.
  • the cavity is located to one side of, and below the fire box 102 and when the valve 110 is closed, flue gasses are directed over the top of the fire box 102 before being drawn downwardly into the cavity where the hot sides of the TEGs and supplementary TEGs 202 are heated.
  • Identical features have been identified using identical reference signs, to avoid unnecessary repetition.
  • the oven 702 additionally comprises a supplementary heating chamber 702 heated by radiated heat 130 from the fire box 102.
  • flue 108 of any of the systems in accordance with the invention described herein could additionally be provided with TEGs 22 affixed to the flue 108, such as that described above in relation to the known TEG-stove 100 of Figure 1.
  • a pair of catalytic converters 119 may be provided in the cavity 112 in such a manner that any flue gases flowing through the cavity also pass through the catalytic converters. As such they may ideally extend across substantially the entire width of the cavity, from front to back in the arrangement shown in Figure 10, and thus provide an active filter for those flue gases.
  • FIG 11 a schematic perspective view of the interior of a stove 100 is illustrated and in which is provided a secondary burning system is provided which consists essentially of a secondary air passageway 800, said passageway 800 being secondary as distinct from the primary air passageway (not shown) which provides air for the combustion of the fuel 14 disposed on the firebox grate 801.
  • passageway 800 is provided with an opening 802 disposed towards the front of the stove through which ambient air may be drawn and which subsequently flows through passageway towards the rear of the firebox alongside the combusting fuel 14.
  • passageway 800 is disposed directly adjacent the firebox so that heat energy from the ongoing combustion and from the walls defining the firebox (and passageway) serve to heat the air having been ingested and flowing through said passageway. Once the superheated air is exhausted through ports 808 into the firebox, it provides an additional source of hot oxygen to fuel a secondary combustion in the upper reaches of the firebox, as distinct from the primary combustion of the fuel 14 occurring in the lower reaches of said firebox.
  • the upper horizontal portion 806 of passageway 800 is disposed adjacent the supplementary vent aperture 114 through which combustion gases (from both primary and secondary combustions) pass into the cavity 112 adjacent the firebox.
  • the invention relates to a combustion apparatus, in particular a stove comprising a combustion vessel and a flue through which combustion gases are exhausted.
  • the combustion vessel has one or more external walls and a first internal dividing wall to an interior side of which is provided a firebox, and to an exterior side of which is provided a cavity defined between said internal dividing wall and at least one of said external walls.
  • the firebox has a flue outlet in fluid communication with the flue and a valve for selectively opening and closing the flue outlet.
  • a supplementary vent aperture Within or at one end of the internal dividing wall is provided a supplementary vent aperture so that combustion gases can flow into the cavity, which is in turn also provided with a flue outlet, particularly when the firebox valve is partially or fully closed.
  • the invention is characterised by providing the supplementary vent aperture and the cavity flue outlet towards first and second ends of the cavity respectively such that combustion gases are constrained to flow through the cavity from said first end toward said second end when the firebox valve is partially or fully closed and in so doing are reheated to some degree by virtue of the adjacency of the cavity and the firebox.
  • thermal energy extraction means is secured to at least one wall of the cavity adjacent which there is some flow of the combustion gases.
  • the thermal energy extraction means is either a plurality of thermoelectric generators (TEGs) or one or more conventional heat exchangers of a back-boiler arrangement.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Solid-Fuel Combustion (AREA)

Abstract

L'invention concerne un appareil de combustion, en particulier un poêle (100) comprenant une cuve de combustion et un conduit de fumée (108) à travers lequel s'échappent des gaz de combustion. La cuve de combustion comporte une ou plusieurs parois externes (124) et une première paroi de séparation interne (113) par rapport à un côté intérieur duquel se trouve un foyer (102), et par rapport à un côté extérieur duquel se trouve une cavité (112) définie entre ladite paroi de séparation interne (113) et au moins l'une desdites parois externes. Le foyer comporte une sortie (104) de conduit de fumée en communication fluidique avec le conduit de fumée et une soupape (110) servant à ouvrir et fermer sélectivement la sortie de conduit de fumée. Une ouverture d'évent supplémentaire (114) est placée à l'intérieur ou au niveau d'une extrémité de la paroi de séparation interne (113) de sorte que les gaz de combustion puissent s'écouler dans la cavité qui est, à son tour, également pourvue d'une sortie de conduit de fumée, en particulier lorsque la soupape (110) de foyer est partiellement ou entièrement fermée. L'invention est caractérisée par la présence de l'ouverture d'évent supplémentaire (114) et de la sortie de conduit de fumée de cavité vers, respectivement, les première et seconde extrémités de la cavité (112), de sorte que les gaz de combustion sont contraints de s'écouler à travers la cavité de ladite première extrémité vers ladite seconde extrémité lorsque la soupape (110) de foyer est partiellement ou entièrement fermée et sont ainsi réchauffés à un certain degré en vertu de la proximité de la cavité et du foyer. Afin d'extraire davantage d'énergie des gaz de combustion réchauffés et de rendre ainsi l'appareil de combustion plus efficace, un moyen d'extraction d'énergie thermique est fixé à au moins une paroi de la cavité adjacente à l'endroit où se produit un certain écoulement des gaz de combustion. Idéalement, le moyen d'extraction d'énergie thermique est constitué soit d'une pluralité de générateurs thermoélectriques (TEG) soit d'un ou de plusieurs échangeurs de chaleur classiques d'un agencement de chaudière arrière.
PCT/GB2015/053788 2014-12-12 2015-12-10 Appareil de combustion à rendement amélioré WO2016092316A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB1422185.7 2014-12-12
GB201422185 2014-12-12
GB201422733 2014-12-18
GB1422733.4 2014-12-18

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WO2016092316A1 true WO2016092316A1 (fr) 2016-06-16

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RU2172448C1 (ru) 2000-03-24 2001-08-20 Заддэ Виталий Викторович Отопительно-варочная печь
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EP2629007A2 (fr) 2012-02-14 2013-08-21 Northern Light Stoves Co. Ltd. Appareil de combustion
DE102013004087A1 (de) 2013-03-11 2014-09-11 Spartherm Feuerungstechnik Gmbh Vorrichtung zum Verbrennen fester Brennstoffe

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Publication number Priority date Publication date Assignee Title
GB2100854A (en) * 1981-06-24 1983-01-06 Merchants Warehousing Company Solid fuel combustion appliances
GB2160643A (en) * 1984-06-05 1985-12-24 Couchman W J R Solid fuel combustion apparatus
GB2187276A (en) * 1986-02-28 1987-09-03 Couchman W J R Solid fuel combustion appliance
DE4435748A1 (de) * 1994-10-06 1996-04-11 Heribert Posch Heizvorrichtung
DE19806428A1 (de) * 1997-02-18 1998-08-20 Patram Patent And Trademark Ad Heizeinrichtung mit verbessertem Wirkungsgrad
US20020148458A1 (en) 1999-06-15 2002-10-17 Andress Alphonso G. Vertical hearth barbecue grill
RU2172448C1 (ru) 2000-03-24 2001-08-20 Заддэ Виталий Викторович Отопительно-варочная печь
US20050034716A1 (en) 2002-12-02 2005-02-17 Lawrence Harbin Portable compact cooking appliance
DE102004034688A1 (de) 2004-07-17 2006-02-16 Öko-Insel Energietechnik GmbH Einrichtung zur Erzeugung von elektrischer Energie aus thermischer Energie, insbesondere Luftheiz- und Konvektionsofen
US7198383B2 (en) 2004-07-17 2007-04-03 Marc Gregory Martino Light emitting art portrayal
EP1734303A2 (fr) * 2005-06-17 2006-12-20 Famaritl (Innovation Technology Lab) S.R.L. Chaudière à combustible granulé à haute récupération d'énergie
US20070204850A1 (en) 2006-02-14 2007-09-06 Pickard Donald W Self powered electric generating food heater
US20080173297A1 (en) * 2007-01-24 2008-07-24 Ardisam High efficiency biomass stove
US20090165772A1 (en) 2007-12-27 2009-07-02 Larry Hunt High efficiency combustion stove
US20100083946A1 (en) 2008-10-07 2010-04-08 Cedar Jonathan M Portable combustion device utilizing thermoelectrical generation
KR20120133452A (ko) 2011-05-31 2012-12-11 한국기계연구원 가정용 보일러의 연통에 설치되는 열전발전장치
WO2013060096A1 (fr) 2011-10-27 2013-05-02 宁波丽辰电器有限公司 Cheminee avec generateur d'energie electrique
EP2629007A2 (fr) 2012-02-14 2013-08-21 Northern Light Stoves Co. Ltd. Appareil de combustion
DE102013004087A1 (de) 2013-03-11 2014-09-11 Spartherm Feuerungstechnik Gmbh Vorrichtung zum Verbrennen fester Brennstoffe

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GB2533222A (en) 2016-06-15

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