Heat recovery reducer

Abstract

The present invention provides a heat recovery reducer for combustion heating of a room comprising an active flue, a passive flue, surrounding at least a portion of the active flue wherein the upper end of the passive flue narrows to a sealing join with the active flue at a location on the active flue spaced apart from the active flue upper and lower ends, the sealing join thereby delineating upper and lower portions of the active flue and an insulation layer enveloping the passive flue and the upper portion of the active flue. The invention further provides a heating system comprising the heat recovery reducer, a method of heating a room, a method of reducing particulate emissions from a combustion heater and a method of manufacturing a heat recovery reducer.

Description

[0001] Heat Recovery Reducer

[0002] Field of the invention

[0003]

[0001] The present invention relates to a combustion heat system and heat recovery reducer assembly for combustion heaters in homes and other buildings to be heated.

[0004] Background of the invention

[0005]

[0002] It is common for homes and other buildings to be heated by the burning or combustion of fuels such as wood, charcoal or gas. The fire may be in an open fireplace or contained in an enclosed firebox. The firebox or other combustion chamber may be further set in a cabinet for additional architectural aesthetics.

[0006]

[0003] Combustion of fuels gives rise to heat and smoke, the smoke and exhaust from the combustion is provided an exit through a flue or chimney to the external environment.

[0007]

[0004] There is significant interest in the efficiency with which buildings can be heated in order to reduce the costs involved and to increase the amount of heating from a fixed amount of fuel. Additionally important are the average power, fuel consumption rate, burn time and the particulate emission factors

[0008]

[0005] As with any method of heating, the efficiency and power output of a combustion fire is important both in terms of the economics of providing heating and the environmental requirements for fuel. Heating output may be measured in terms of kW produced from the mass of fuel with a certain calorific value over a measured period of time.

[0009]

[0006] Combustion fires are known to produce emissions including particulate matter (PM), carbon monoxide, carbon dioxide, nitrogen oxides, organic compounds such as formaldehyde, benzene, volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons.

[0010]

[0007] Contemporary combustion space heating such as for burning wood, charcoal or gas for domestic heating suffer from a number of disadvantages. These include a low rate of conversion of the fuel to heat and thereby a low power output per unit of fuel. Being mindful of environmental effects of combustion, existing heating units additionally cause a high level of emissions to be released into the atmosphere. Accordingly, it is desirable to provide improvements in heating efficiency and reduction of emissions. Summary of the Invention

[0011]

[0008] Combustion heating systems must find the optimal balance between competing requirements such as the need for the fuel to be burned at a sufficiently high combustion temperature to provide heat and the need to avoid heat damage to surrounding structures in the building.

[0012]

[0009] Additionally, there is an inherent need to burn fuels for heat while limiting the amount of unbumed products such as carbon monoxide, hydrogen, carbon, nitrogen oxides and particulate emissions to the environment.

[0013]

[0010] The present invention is predicated in part on the surprising observation that, contrary to expectation, that significant improvements in heating efficiency and reduction in particulate emissions can be made.

[0014]

[0011] Accordingly in one aspect of the present invention, there is provided a heat recovery reducer for combustion heating a space comprising: an active flue having upper and lower ends, an inner surface and an outer surface, forming a continuous active flue passage, a passive flue, having upper and lower ends, surrounding at least a portion of the active flue wherein;

[0015]

[0012] the upper end of the passive flue narrows to a sealing join with the outer surface of the active flue at a location on the active flue spaced apart from the active flue upper and lower ends,

[0016]

[0013] the sealing join thereby delineating upper and lower portions of the active flue and

[0014] an insulation layer providing insulation to the passive flue and the upper portion of the active flue,

[0017]

[0015] characterised in that a heat recovery chamber is formed between the passive flue and the lower portion of the active flue.

[0018]

[0016] In an embodiment of the heat recovery reducer the passive flue is essentially concentric with the active flue, the diameter of the passive flue being larger than the active flue.

[0019]

[0017] Advantageously the insulation layer provides insulation for the entire outer circumference of the heat recovery reducer.

[0020]

[0018] Preferably the continuous active flue passage is essentially vertical in use to convey the flue gases upward.

[0021]

[0019] In an embodiment of the heat recovery reducer the insulated portion of the passive flue and the upper portion of the active flue are additionally comprised of twin walls and the void between the twin walls is essentially filled with insulation material. Preferably the twin walls are constructed of 1mm stainless steel for durability.

[0020] Importantly, the heat recovery reducer is sealed which prohibits escape of warm aire from the heated space out to the external environment.

[0022]

[0021] Preferably the upper end of the passive flue narrows frusto-conically to a sealing join with the outer surface of the active flue.

[0023]

[0022] More preferably the insulation layer has a thermal resistance of 1200 degrees Celsius and the insulation material is ceramic, approximately 1 inch thick and insulates the circumference of the passive flue and the upper portion of the active flue. Even more preferably the ceramic insulation comprises ceramic fibre blanket or ceramic wool within the twin walls.

[0024]

[0023] In an embodiment of the heat recovery reducer the outer passive flue twin walls are 10 inches and 12 inches in diameter. Preferably the inner active flue is not insulated and is single walled, 6 inches in diameter stainless steel to allow maximum transfer of heat from the heated smoke through to the heat recovery chamber.

[0025]

[0024] In a further embodiment of the invention, there is provided the heat recovery reducer, further comprising an air exchange region of the heat recovery chamber wherein the air exchange region essentially comprises an opening in the outer passive flue thereby allowing heated air from the heat recovery chamber to exchange with air within the space to be heated.

[0025] Preferably the air exchange region extends around the circumference of the outer passive flue and is covered by a mesh or grille. More preferably the air exchange region is located near the lower end of the passive flue.

[0026]

[0026] In a further embodiment of the invention the heat recovery reducer further comprises a cowl located at the upper end of the active flue. Preferably the cowl has insulated walls.

[0027]

[0027] In a further aspect is provided a heating system comprising the heat recovery reducer wherein the lower end of the active flue is sealingly attached to the outlet spigot of a heating appliance thereby enabling the direct egress of combustion smoke from the heating appliance into the active flue.

[0028]

[0028] A further aspect of the invention provides a method of combustion heating a space with a combustion heating unit, the method comprising providing a fire in a heating appliance sealingly attached to a heat recovery reducer of the invention.

[0029]

[0029] In yet a further aspect of the invention there is provided a method of reducing particulate emissions from a combustion fire, the method comprising providing a fire in a heating appliance sealingly attached to a heat recovery reducer as herein described.

[0030]

[0030] In yet another aspect there is provided a method of providing a temperature in a heat recovery chamber that is greater than about 280C the method comprising providing a fire in a heating appliance sealingly attached to a heat recovery reducer as herein described. It is a surprising feature disclosed by the inventors that the transmission of the smoke heat through the single-walled active flue from the active flue passage to the heat recovery chamber, generates raised temperatures in the heat recovery chamber and that this thermal effect raises the temperature in the heat recovery chamber significantly higher than conventional flue systems. The inventors observed temperatures exceeding about 280C. Advantageously this elevated temperature results in the destruction of emissions such as particles and consequent reductions of emissions from the heating unit into the environment.

[0031]

[0031] In a further aspect of the invention there is provided a method of manufacturing a heat recovery reducer, the method comprising the steps of:

[0032]

[0032] providing an active flue having upper and lower ends, forming a continuous active flue passage

[0033]

[0033] providing a passive flue having upper and lower ends, surrounding at least a portion of the active flue, joining the upper end of the narrowed passive flue in a sealing join with the outer surface of the active flue at a location on the active flue spaced apart from the active flue upper and lower ends, thereby delineating upper and lower portions of the active flue, so that a heat recovery chamber is formed between the passive flue and the lower portion of the active flue and enveloping the passive flue and the upper portion of the active flue in an insulation layer.

[0034]

[0034] A heat recovery reducer for combustion heating of a space comprising: an active flue having upper and lower ends, an inner surface and an outer surface, forming an active flue passage a passive flue, having upper and lower ends, surrounding at least a portion of the active flue wherein; the upper end of the passive flue narrows to a sealing join with the outer surface of the active flue at a location on the active flue spaced apart from the active flue upper and lower ends, the sealing join thereby delineating upper and lower portions of the active flue and an insulation layer providing insulation to the passive flue and the upper portion of the active flue, characterised in that a heat recovery chamber is formed between the passive flue and the lower portion of the active flue.

[0035]

[0035] The heat recovery reducer wherein the active flue is straight.

[0036]

[0036] The heat recovery reducer wherein the passive flue is essentially concentric with the active flue, the diameter of the passive flue being larger than the active flue.

[0037]

[0037] The heat recovery reducer wherein the active flue passage is essentially vertical.

[0038]

[0038] The heat recovery reducer wherein the insulation layer of the passive flue and upper portion of the active flue is twin-walled and the void between the twin walls is essentially filled with insulation.

[0039]

[0039] The heat recovery reducer wherein the twin walls are constructed of 1mm stainless steel.

[0040] The heat recovery reducer wherein the insulation layer has a thermal resistance of 1200 degrees Celsius.

[0041] The heat recovery reducer wherein the insulation is ceramic fibre blanket.

[0040]

[0042] The heat recovery reducer wherein the insulation is approximately 1 inch thick.

[0041]

[0043] The heat recovery reducer wherein the insulation layer provides insulation for the entire circumference of the heat recovery reducer including the passive flue and the upper portion of the active flue.

[0042]

[0044] The heat recovery reducer wherein the passive flue twin walls are 10 inches and 12 inches in diameter.

[0043]

[0045] The heat recovery reducer wherein the lower portion of the active flue is not insulated.

[0046] The heat recovery reducer wherein the lower portion of the active flue is single walled.

[0047] The heat recovery reducer wherein the sealing join extends around the entire circumference of the active flue.

[0044]

[0048] The heat recovery reducer wherein the active flue and passive flue are concentrically aligned.

[0045]

[0049] The heat recovery reducer wherein the active flue is 6 inches in diameter stainless steel.

[0050] The heat recovery reducer further comprising an air exchange of the heat recovery chamber wherein the air exchange essentially comprises an opening in the passive flue thereby allowing heated air from the heat recovery chamber to exchange with air in the space to be heated.

[0046]

[0051] The heat recovery wherein the air exchange opening extends around the circumference of the passive flue.

[0047]

[0052] The heat recovery reducer wherein the air exchange opening is covered by a mesh or grille.

[0048]

[0053] The heat recovery reducer wherein the air exchange opening is located near the lower end of the passive flue.

[0049]

[0054] The heat recovery reducer further comprising a cowl located at the upper end of the active flue.

[0050]

[0055] The heat recovery wherein the cowl has insulated walls.

[0051]

[0056] A heating system comprising the heat recovery reducer wherein the lower end of the active flue is sealingly attached to the outlet spigot of a heating appliance thereby enabling the direct egress of combustion smoke from the heating appliance into the active flue.

[0052]

[0057] A method of combustion heating a room, the method comprising providing a fire in a heating appliance of the disclosure.

[0053]

[0058] A method of reducing particulate emissions from a combustion fire, the method comprising providing a fire in a heating appliance of the disclosure.

[0059] The method of reducing particulate emissions from a combustion fire in that the temperature in the active flue at about 1.8m above the heating appliance outlet spigot is at least about 280C.

[0054]

[0060] A method of manufacturing a heat recovery reducer, the method comprising the steps of:

[0061] providing an active flue having upper and lower ends, forming a continuous active flue passage providing a passive flue having upper and lower ends, surrounding at least a portion of the active flue joining the upper end of the narrowed passive flue in a sealing join with the active flue at a location on the active flue spaced apart from the active flue upper and lower ends, thereby delineating upper and lower portions of the active flue, so that a heat recovery chamber is formed between the passive flue and the lower portion of the active flue and enveloping the passive flue and the upper portion of the active flue in an insulation layer.

[0055] Description of the figures

[0056] Figure 1 A is a cut-away sectional view of an embodiment of the heat recovery reducer of the present invention.

[0057] Figure IB is a complete external view of a heat recovery reducer.

[0058] Figure 2A illustrates a cut-away of a typical installed heating system with a heat recovery reducer.

[0059] Figure 2B illustrates an external view of a typical installed heating system with a heat recovery reducer.

[0060] Figure 3 A shows a sectional cut-away illustration of the air exchange section of the passive flue.

[0061] Figure 3B shows the external view of the air exchange section of the passive flue.

[0062] Figure 4 is a cut-away illustration of the cowl that provides a shaped covering to the top of the active flue when installed.

[0063] Detailed description of the invention

[0064] Heat Recovery Reducer

[0065]

[0062] The present invention has been developed with the aim of providing an improved solution to the heating efficiency and environmental emissions of combustion heaters. The inventors have disclosed a new and advantageous heat recovery reducer for recovery of heat from the flue gases and smoke released by combustion heating. This heat is advantageously returned to the room that is to be heated.

[0063] The heat recovery reducer is placed in an essentially vertical orientation in order to conduct rising hot smoke from a combustion heating unit.

[0066]

[0064] As shown in Figure 1 A, the heat recovery reducer (10) comprises an active flue (12), a passive flue (14), and an insulation layer (16). The insulation layer (16) is twin-walled with an outer wall (18) and inner wall (20). The inner cylindrical active flue pipe is a continuous cylinder of approximately 6 inches (15.25cm) diameter, defining an active flue passage (30) in the central bore, open at each end.

[0067]

[0065] The gap between the inner wall and outer wall of the twin wall is filled with a 25 mm thick ceramic fibre blanket insulation layer (22). The active flue is constructed of 6 inch diameter 1mm stainless steel for strength and durability.

[0068]

[0066] The passive flue of the heat recovery reducer narrows in a frusto-conical shape from 10- 12 inches diameter twin-wall to the active flue. The sealing join is formed by welding to ensure a robust airtight seal. The outer conical twin-wall, has a 25mm thick ceramic fibre blanket insulation layer. The heat recovery reducer is responsible for reducing the heat recovery reducer’s size from a diameter of 10"-12" down to 6"-8". This reduction functions to improve the efficiency of the heating process and reducing emissions.

[0069]

[0067] The internal wall of the outer twin-wall is a 10-inch (25.4cm) diameter heavy-duty stainless steel construction and the outer wall is a 12 inch (30.5cm) heavy duty stainless steel. The insulation layer (22) defined between the internal and external walls is filled with a ceramic fibre blanket insulation layer of approximately 1 inch (25mm) thickness with a thermal resistance of at least 1200 degrees Celsius sufficient to withstand the considerable heat of a combustion fire. This serves to protect the external surrounding structures in the room or building from thermal damage.

[0070] Heat Recovery Chamber

[0071]

[0068] The passive flue (14) is a larger diameter than the active flue (12), thereby forming a heat recovery chamber between them. The narrowed top of the passive flue is welded to the active flue to provide an airtight seal at the top of the heat recovery chamber (26).

[0072]

[0069] One of the key functions of the heat recovery chamber (26) that is formed between the passive flue and the active flue is to prevent the heat from escaping through the active flue, creating a thermal "hot air blanket" of extremely hot air around the active flue. This not only increases the overall efficiency of the heating appliance but also contributes to a cleaner burn, reducing emissions. Smoke of the fire that is burning in the appliance rises through the active flue, heating the wall of the active flue, with the resultant heat transfer from the smoke in the active flue (30) to the air in the heat recovery chamber (26). Heating System

[0073]

[0070] The heating system shown in Figure 2, (40) is an assembly of a fire box (42), air exchange section (44), active flue pipe (46), twin walled passive flue (48), heat recovery reducer (10), straight twin-wall insulated active flue (50) and twin-wall insulated cowl (80).

[0074]

[0071] As will become evident, the heating unit has an integrated active flue, designed to work seamlessly together. When connected, these individual elements create a unified and robust piece that attaches to the outlet spigot on top of a combustion heating appliance. To connect the components of the heating system, twist lock attachments are used, providing a secure and reliable connection. To ensure a tight and secure connection, 6" easy-seal flat clamps are utilised between sections. This clamp prevents any smoke or gas leakage, maintaining the safety and effectiveness of the combustion heater and heating system.

[0075]

[0072] All steel components are constructed from 1mm thick stainless steel. This material ensures appropriate heat transfer, durability and longevity.

[0076] Insulation

[0077]

[0073] The twin-wall insulated passive flue and the active flue effectively retains heat within the heat recovery chamber and also acts as a protective barrier, preventing exposure of nearby combustible materials to high temperatures.

[0078] Active Flue

[0079]

[0074] The active flue extends continuously rising up from the heating appliance, through the room and ceiling continuously through the heat recovery reducer and the twin-walled insulated flue to terminate at its top, being topped by the twin-wall insulated cowl.

[0080]

[0075] The active flue extends from the heating appliance fire box and is fixed to the firebox so that the hot combustion smoke exits through the central bore of the active flue. The active flue thereby forms a continuous conduit from the fire box at its lower end up through the heat recovery reducer to its apex at the twin-wall insulated cowl.

[0081]

[0076] The heat recovery reducer is placed above a standard commercially available heating appliance, where at the lower end there are two essentially concentric flues. The concentric flues consist of an internal active flue and an outer insulated passive flue. Notably the inventors have provided a heating unit which avoids the common disadvantage of permitting a gap surrounding the active flue through which air can escape to the external environment. Air Exchange

[0082]

[0077] Within the dwelling room or building that is being heated is also located the lower end of the insulated passive flue. The insulated passive flue includes an air temperature exchange (60) depicted in figure 3. The air temperature exchange has cylindrical steel mesh or grille (62) for a vertical region of the insulated passive flue and extends around the circumference of the insulated passive flue. The steel mesh is constructed of high-grade stainless steel with mesh openings sufficiently sized to accommodate natural or assisted air exchange between the room and the heat recovery chamber (26). The mesh or grille may be constructed of openings that are a range of common shapes such as squares, diamonds, rectangles or circles for visual appeal. It will be apparent that the exchange region facilitates the enhanced heating of the room, or other space, with the heated air in the heat recovery chamber. This exchange may be further facilitated with a fan. The combination effect is that the heat recovery chamber achieves higher temperatures with the concomitant benefit of reducing the particle emissions in the smoke as well as increasing the heat output to the room. The enhanced heating efficiency to the room is achieved by the combination of airtight seals which prevent any egress of air from the room to the environment in addition to the air exchange between the heat recovery chamber and the room.

[0083] Connecting twin-wall insulated active flue

[0084]

[0078] At the top of the upper portion of the active flue of the heat recovery reducer are connected additional lengths of twin-wall insulated active flue (50). In a similar fashion to the passive flue, this has inner (six inch) and outer (eight inch) diameter walls defining a 1-inch ceramic fibre blanket insulation layer between. The connecting twin-wall insulated active flue functions to extend upwardly through the ceiling space and roof line into the surrounding external environment in order to exhaust the flue smoke and gases. This connection allows for the proper exhaust of smoke generated during the combustion process.

[0085] Thin-wall insulated cowl

[0086]

[0079] The top of the twin wall insulated active flue is a twin-wall insulated cowl (80) shown in figure 4. The cowl section narrows from an internal diameter of 6 inches, maintaining the insulated twin-wall, terminating at the apex with three or more cowl support posts (84). The cowl walls are insulated in order to maintain the elevated temperature of the flue gasses through to evacuation into the environment. The cowl support posts are fixed to the apex and extend upwardly. The cowl top-piece (86) is a domed or hat-shaped high grade steel structure that functions to limit the ingress of environmental contaminants such as rain, hail, and snow while allowing unimpeded egress of combustion smoke. The cowl top-piece (86) is fixed to the top of the cowl support posts (84).

[0087] Reducing emissions

[0088]

[0080] The disclosure of the current invention provides significant and unexpected benefits in reducing emission from the combustion fire into the external environment. This is particularly important to reduce the damaging environment effects and meet increasingly stringent environmental emission standards. This surprising benefit is attained by the elevated temperatures at which the active flue reaches during use. When measurements are taken in the active flue, at a height of 1.8 metres above the discharge spigot of the combustion heating appliance, a temperature of at least about 280C was reached. This surprisingly elevated temperature in the active flue causes the thermal destruction of particulate emissions in the smoke.

[0089] Installation Details

[0090]

[0081] Each section is securely connected and sealed to the adjoining sections through male to female connections. Twist lock attachments are also used for connecting components.

[0091]

[0082] These are secured by drilling holes and pop riveting using stainless steel pop rivets. Additional sealing is carried out using 6” flat band clamps to clamp around the join of each pair of sections to be joined. The nuts on the 6” flat band clamp are tightened using a ratchet gun and a 14mm spanner.

[0092]

[0083] Comprises / comprising and grammatical variations thereof when used in this specification are to be taken to specify the presence of stated features, integers, steps or components or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0093] Experimental Results

[0094]

[0084] Experiment 1 : Comparison testing of commercially available Appliance #1 with and without the heat recovery reducer was performed according to the requirements of the joint Australian / New Zealand Standard AS / NZS 4012 / 4013 (2014). The appliance was tested using hardwood as the test fuel. This test fuel was used after conforming to the requirements of the joint AS / NZS 4014.1.

[0095] Installation of the appliance

[0096]

[0085] The commercially available heating appliance firebox was measured according to the method described in the joint standard AS / NZS 4012. The appliance fuel load, fuel length and number of wood pieces were then calculated as per section 5 of AS / NZS4012.

[0097]

[0086] Prior to testing, the appliance was burnt for a minimum of 16 hours (two x 8 hours) as per section 6.1.2 of AS / NZS4012:2014.

[0098]

[0087] Testing was conducted according to the manufacturer’s verbal or written instructions (joint AS / NZS 4013 Paragraph 8.20[c]).

[0099] Procedure

[0100]

[0088] The test fuel was loaded according to the manufacturer’s instructions.

[0101]

[0089] Power Output and Thermal Efficiency (AS / NZS4012)

[0102]

[0090] Testing used a calorimetry room which is an insulated room (75 mm thick polystyrene lined on walls, floor and ceiling) of internal dimensions 3.0 m * 3.0 m * 2.4 m high.

[0103]

[0091] Air flow into the room is via a 300 mm diameter duct from a manually controlled variable speed fan. Air flow out of the room is via a 300 mm diameter duct also connected to a variable speed fan. The outlet duct air pressure is kept at 57Pa (recorded on Dywer digital 607D- 11 manometer) while the inlet air fan speed is adjusted via the variable speed drive to keep the calorimeter room at atmospheric pressure, (by use of a Dwyer digital DP 607D-02 manometer)

[0092] Air flow temperatures are measured by three type K thermocouples (batch calibrated by ECE Fast report 14705) in both the inlet and outlet ducts. The appliance being tested sits on a 0 - 600 kg digital platform scales (Ohaus VE1500RA). The flue system consists of an insulated silicone oil bath that isolates the weight of the appliance from the remainder of the flue. The flue, where it exits from the room, passes into an insulated flue casing. Total flue length above the top of the scales is set at 4.6 ±0.1 m.

[0104]

[0093] Temperatures and transducer signals are fed to a National Instruments DAQMX that is connected to a computer. A digital signal from the scales is also sent to the computer. The ASFT Labview / SQL designed computer program records all data and displays real-time results as they are collected.

[0105]

[0094] The calorimeter room heat losses through the walls have been measured and accounted for by calibration from an electrical resistance heater of known output (NATA certified kWhr meter).

[0106] Particulate Emissions (AS / NZS4013)

[0107]

[0095] The emissions equipment consists of a dilution tunnel, collection hood, pitot tube and NATA certified digital manometer (Dwyer digital DP 607D-02) for air flow measurement and sampling train / probe.

[0108]

[0096] The sampling train / probe consists of a sample probe, double filter assembly, including thermocouple, a gas drier, vacuum pump and NATA certified gas meter (Landis & Gyr).

[0109]

[0097] Grade 333, forty-seven millimetre glass fibre filters are pre-weighed (by way of Ohaus PA114C balance) and are mounted in the filter assembly.

[0110]

[0098] Data from thermocouples, manometer and dry gas meter is fed to a National Instruments DAQMX and ASFT’s labview / SQL designed computer program. The particulate emissions information is collected at the same time as data from the calorimeter room.

[0111]

[0099] At the completion of a burn cycle, the filters are removed from the filter holders and placed in a desiccator for drying. Condensed and entrapped emissions from the sample probe are washed with acetone into a glass beaker. A rifle cleaning rod is used to clean the inside of the sampling probe. The cleaning rod is then washed with acetone (into the glass beaker). The acetone washing is allowed to vaporise to dryness and the residue weight determined. The two dried filters are re-weighed.

[0112]

[0100] Emission weight is then determined by totalling the filter weight increases from the two filters and the residue from acetone washings. Test Fuel

[0113]

[0101] The appliance was fired using the fuel type specified in the table below;

[0114] Fuel Type Hardwood

[0115] Common Name Redgum

[0116] Scientific name Eucalyptus carnal dulensis

[0117] Average Fuel load 9.4kg

[0118] Average moisture content 15.4%

[0119] Dry density 0.86kg / L

[0120] Fuel length 288mm

[0121] No. of pieces 6

[0122] Method of loading (fuel Front to Rear, 2 on 4 placement)

[0123] Calorific Value (Gross Dry) 20.5MJ / kg Ash Content 0.1% db

[0124]

[0102] The Appliance #1 with the heat recovery reducer on the high bum rate produced a 28% increase in power output, a 32% increase in the maximum power output, 14% increase in efficiency and a 70% reduction in particulate emissions.

[0125]

[0103] On the medium burn rate setting, the Appliance #1 with the heat recovery reducer produced a 13% increase in power output, 7% increase in efficiency and a 70% reduction in particulate emissions.

[0126]

[0104] On the low burn rate setting, the Appliance #1 with the heat recovery reducer produced the same power output, 3% increase in efficiency and a 20% increase in particulate emissions.

[0127]

[0105] Overall, the Appliance #1 with the heat recovery reducer produced a 15% increase in power output, 8% increase in efficiency and a 54% reduction in particulate emissions. The heat recovery reducer uses the excess heat from the active flue pipe to distribute hot air to the room. This is why a much higher increase in power output and efficiency on the high bum settings is observed, when the flue temperature is much higher.

[0128]

[0106] Experiment 2: Comparison testing of the four solid fuel commercial heating appliances with and without the heat recovery reducer was performed according to the requirements of the joint Australian / New Zealand Standard AS / NZS 4012 / 4013 (2014).

[0129]

[0107] The four solid fuel appliances fitted with the heat recovery reducer on the high bum rate produced a 90% increase in power output, a 72% increase in the maximum power output, 29% increase in efficiency and a 68% reduction in particulate emissions. On the low burn rate setting, the four solid fuel appliances fitted with the heat recovery reducer produced similar power output, 50% increase in efficiency and a similar particulate emissions factor. Overall, the four solid fuel appliances fitted with the heat recovery reducer produced a 36% increase in power output, 17% increase in efficiency and 34% reduction in particulate emissions.

Claims

Claims1. A heat recovery reducer for combustion heating of a space comprising: an active flue having upper and lower ends, an inner surface and an outer surface, forming an active flue passage a passive flue, having upper and lower ends, surrounding at least a portion of the active flue wherein; the upper end of the passive flue narrows to a sealing join with the outer surface of the active flue at a location on the active flue spaced apart from the active flue upper and lower ends, the sealing join thereby delineating upper and lower portions of the active flue and an insulation layer providing insulation to the passive flue and the upper portion of the active flue, characterised in that a heat recovery chamber is formed between the passive flue and the lower portion of the active flue.

2. The heat recovery reducer according to claim 1 wherein the active flue is straight.

3. The heat recovery reducer according to claim 1 or 2 wherein the passive flue is essentially concentric with the active flue, the diameter of the passive flue being larger than the active flue.

4. The heat recovery reducer according to any one of claims 1 to 3 wherein the active flue passage is essentially vertical.

5. The heat recovery reducer according to any one of claims 1 to 4 wherein the insulation layer of the passive flue and upper portion of the active flue is twin-walled and the void between the twin walls is essentially filled with insulation.

6. The heat recovery reducer according to claim 5 wherein the twin walls are constructed of 1mm stainless steel.

7. The heat recovery reducer according to any one of claims 1 to 6 wherein the insulation layer has a thermal resistance of 1200 degrees Celsius.

8. The heat recovery reducer according to claim 1 to 7 wherein the insulation is ceramic fibre blanket.

9. The heat recovery reducer according to any one of claims 1 to 8 wherein the insulation is approximately 1 inch thick.

10. The heat recovery reducer according to any one of claims 1 to 9 wherein the insulation layer provides insulation for the entire circumference of the heat recovery reducer including the passive flue and the upper portion of the active flue.

11. The heat recovery reducer according to any one of claims 5 to 10 wherein the passive flue twin walls are 10 inches and 12 inches in diameter.

12. The heat recovery reducer according to any one of claims 1 to 11 wherein the lower portion of the active flue is not insulated.

13. The heat recovery reducer according to any one of claims 1 to 12 wherein the lower portion of the active flue is single walled.

14. The heat recovery reducer according to any one of claims 1 to 13 wherein the sealing join extends around the entire circumference of the active flue.

15. The heat recovery reducer according to any of claims 1 to 14 wherein the active flue and passive flue are concentrically aligned.

16. The heat recovery reducer according to any one of claims 1 to 15 wherein the active flue is 6 inches in diameter stainless steel.

17. The heat recovery reducer according to any one of claims 1 to 16, further comprising an air exchange of the heat recovery chamber wherein the air exchange essentially comprises an opening in the passive flue thereby allowing heated air from the heat recovery chamber to exchange with air in the space to be heated.

18. The heat recovery reducer according to claim 17 wherein the air exchange opening extends around the circumference of the passive flue.

19. The heat recovery reducer according to claim 17 or 18 wherein the air exchange opening is covered by a mesh or grille.

20. The heat recovery reducer according to any one of claims 17 to 19 wherein the air exchange opening is located near the lower end of the passive flue.

21. The heat recovery reducer according to any one of claims 1 to 20 further comprising a cowl located at the upper end of the active flue.

22. The heat recovery reducer according to claim 21 wherein the cowl has insulated walls.

23. A heating system comprising the heat recovery reducer according to any one of claims 1 to 22 wherein the lower end of the active flue is sealingly attached to the outlet spigot of a heating appliance thereby enabling the direct egress of combustion smoke from the heating appliance into the active flue.

24. A method of combustion heating a room, the method comprising providing a fire in a heating appliance according to claim 23.

25. A method of reducing particulate emissions from a combustion fire, the method comprising providing a fire in a heating appliance according to any one of claims 23 to 24.

26. The method of reducing particulate emissions from a combustion fire according to claim 25 characterised in that the temperature in the active flue at about 1.8m above the heating appliance outlet spigot is at least about 280C.

27. A method of manufacturing a heat recovery reducer, the method comprising the steps of: providing an active flue having upper and lower ends, forming a continuous active flue passage providing a passive flue having upper and lower ends, surrounding at least a portion of the active flue joining the upper end of the narrowed passive flue in a sealing join with the active flue at a location on the active flue spaced apart from the active flue upper and lower ends, thereby delineating upper and lower portions of the active flue, so that a heat recovery chamber is formed between the passive flue and the lower portion of the active flue and enveloping the passive flue and the upper portion of the active flue in an insulation layer.

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