TITLE: Biofuel pellet based cook stove with variable sizes and automation
FIELD OF INVENTION;
The present inversion is related to an innovative and versatile cooking stove. The present invention provides cooking stove with unique feature like; combustion chamber without refractory, complete combustion of fuel, balanced air supply system through air box, noiseless and smokeless operation, moveable structure, compact, combustion chamber with secondary air hole in descending order with zigzag pattern, passive cooling body design and control panel with mechanism for speed variation with voltage control, voltage display with charging indicator, in-built battery backup, radio player with channel & volume keys, USB port for mobile charging and music. The stove is invented to use almost all kinds of pelletized fuel with diameter up to 10 mm, length up to 50 mm and ash percentage up to 20 w't %. With adjustable voltage frequency said invention is suitable for all kind of cooking methods like; frying, backing, steaming, roasting, boiling etc.
BACKGROUND OF INVENTION:
Biomass is extremely abundant and contributes in great extent as energy source in rural parts of the world. Now with development of combustion engineering, processed and modified biomass in form of pellets, briquettes and other forms are being focussed as alternate source of energy. Charcoal and wood is most favorable option as fuel for cooking in all developing countries and it is resulting into increasing deforestation, indoor air pollution and several environmental problem like; desertification, floods, erosion, drought, etc. In addition to that considerable factors like- low fuel efficiency, traditional stove design, cooking pattern, use of cow dung as fuel, and architectural custom are contributing to harmful smoke, which is considered as the worst health problem for children under 5 years age in developing countries. As per the WHO, nearly two million people worldwide die every year due to indoor smoke pollution, its impact is more on women and children as compared to men.

These are the driving factors for government, companies & researcher to focus on this matter and derive some solutions. As a result, in last two decades several cook-stove programs and various other efforts have been made by companies, governments and international organizations in research and implementation of improved cook-stoves in the rural and urban areas and in many countries it has been introduced with subsidies also.
Pellet stove is a way for better utilization of biomass and thus improving the health of the person involved in cooking & surrounding environment. The pellet stove has changed in appearance over the years from a simple, boxy workhorse design, to a decorative heating appliance. Pellet stoves can be either free-standing units or fireplace inserts vented into an existing chimney. Most pellet stoves are constructed using large, conductive, steel or cast-iron pieces, with stainless steel to encase circuitry and exhaust areas. The heating industry has considerably shifted toward biomass stoves and heating devices based on efficient combustible and renewable resources. This was a trend that began during the 1973 oil crisis causing the creation of the first pellet stoves. Still few unresolved problems are there in cook-stoves which directly affect the performance, efficiency, self life of stove, affordability and popularity. Major considerable factors are- suitability for specified fuel, low efficiency, high cost as compared to LPG and Kerosene stove, lack of automation, ash & clinker problem, duration of stove operation, lack of regulation of flame as per requirement and maintenance of stove too.
Prior Arts :
There have been many attempts to design efficient biomass based cook stove. Pellet stoves have become a viable, economical, and popular option for home heating systems only in the last ten years. Few disclosures like US Patent 5,429,110, the innovation is mainly concentrating on heat insulation issues. While establishing a cold and a hot compartment separated by a double layer wall where air flow is circulating, they ensure stability at the

required temperature in the pellet storage and electrical components. However the heat transfer between the cooked stuff and the superheated air is not optimized, and the exhaust goes through the cooking dish before spreading in the kitchen.
According to the patent US 5,123,360, the innovation consists in an optimization of air circulation by splitting the supply stream for different uses: combustion air feeding, depressurization of the combustion chamber, heat exchange (heat the inlet air and cool the exterior of the devices), preventing back flue gas in auger feed. However the main function of this innovation is air heating. As a result, cooking efficiency and diversity in types of cooking are reduced.
US Patent 5,429,110, the innovation is mainly concentrating on heat insulation issues. While establishing a cold and a hot compartment separated by a double layer wall where air flow is circulating, they ensure stability at the required temperature in the pellet storage and electrical components. However the heat transfer between the cooked stuff and the superheated air is not optimized, and the exhaust goes through the cooking dish before spreading in the kitchen.
In EP2085694A2, it discloses a method for controlling a wood burning stove including a combustion chamber with glass door, which is downwards separated from an ash chamber by means of a grate bottom and having a walling at the rear and at both sides. The combustion chamber upwards preferably via a reversing plate being connected with a chimney via a flue gas exhaust, the wood burning stove including an electronic control which includes a thermal sensor and a A-probe. The air ducts being disposed side by side at a rear side of the wood burning stove.
In US 5873356, the invention discloses a wood pellet stove for burning wood pellets and

especially burning pellets at low burns, stove has microprocessor based control for air regulation and pellet feeding to combustion pot. The microprocessor is further used to monitor inlet air temperature and exhaust gas temperature. The burn pot includes a burn grate and pit used for receiving and burning Wood pellets. The burn pot is disposed on a fire box floor and stove is characterized by having heat exchanger panels.
US 7861707 B2, describe about a pellet stove utilizing gravity feed and natural draft more effectively and efficiently burns pellet fuel While producing less air pollution and ash. One of major claim, the pellet stove has a primary combustion area comprising a burn unit removable disposed in the vent rube, a feed tube defining a fuel chamber above the burn unit and a secondary combustion area, comprising a burn box defining a secondary burn chamber.
In US7380548 B2, A stove comprising a frame bounding an area to receive a burner, a heating cavity assembly mount upward and having four side walls and a bottom wall having an opening therein, and a collar mounted in the heating cavity assembly around the opening. Front, rear, and side panels are mounted on the frame to enclose the side Walls of the heating cavity assembly.
The Patent WO 2010/029567 A2 describes the design of an innovative stove presenting some specific features to obtain a complete combustion and a very good energy efficiency in any range of temperature required for cooking. Therefore, they elaborate a technology with a fire pot with variable volume while having a grate with adjustable height. Moreover the combustion is done along two stages. The primary and the secondary benefit two independent fresh air flow input in order to get an accurately complete combustion. However there is no automatic feeding systems. This missing element induce a lack of flexibility in the required temperature as well as in the firing and switching off duration.

In US7318431 Bl, the invention disclose a biomass pellet burning stove with hopper for storage of biomass pellets, transfer of pellets from hopper to burn pot by feeder tube. The burn pot has first and second combustion chamber. In US6213116 Bl, disclosed a wood or multi-fuel stove comprises a primary combustion chamber. The grate in invention is extending from the front to Wards the back of the stove interior and having a front edge juxtaposed With the front of the stove; a secondary combustion chamber located beneath the grate linked to the primary combustion chamber.
Combination and integration of the ergonomic, fuel compatibility, safety, and health aspect up to now has not been deeply focused upon in biomass fuel pellets based cooking stove design. Most of the prior art mention above has no answer for few parameter like; the irritating noise during stove operation, incomplete combustion, blackening of vessel & cooking area, environmental emission, gestation period between subsequent stove operation, smart control and stove combustion compatibility with various kind of fuel pellet made from virgin or proceeded biomass. Present invention relates to advance cook- stove by taking care and overcome of all limiting factor as mention above.
SUMMARY OF THE PRESENT INVENTION
The invention relates to a stove incorporating, a combustion chamber without refractory, well ergonomic to support complete combustion of fuel, air box system to supply proper air, noiseless and smoke less operation, compact & moveable structure, passive cooling body design, flexibility for fuel holding capacity by changeable fire pot/combustion chamber, separate vessel holding stand, panel with charging indicator, voltage display, mobile charging port, radio player with channel & volume keys. The fire pot with perforated grate at bottom and having series of 5mm, 6mm and 6 mm holes on top in descending orders. The fire bed received an air supply through air-box powered by three high speed fans at air

inlet duct at 45° angle. The flames heat the cooking vessel which is being held by separate stand on top oi the fire pot. Fire pot is covered by two layer of galvanized sheet, cavity filled by cerawool to provide proper insulation. Outer layer is of stainless still with air pocket for passive cooling. Stove design is compatible for range of fuel pellets made out of virgin and processed biomass with ash percentage 1 to 20 %, diameter up to 10mm and length up to 50mm.
The main aspect of the present invention is to provides stove with characteristic features that make it unique for its safe and clean eco-friendly operation. The stove shell assembly is separate from the cooking vessel loading structure, it make stove operation with zero cooking vessel load. The unique ergonomic structure of stove provides smoke less & noise less operation, minimum/near to zero heat loss from side wall and bottom, cooking area remain cool during stove operation, no blackning of cooking vessels, complete combustion, efficient heat transfer, compatible with range of fuel pellets, operate with equal efficiency even if one of the high speed electric fan is not working, replaceable fire-pot/combustion chamber with different fuel holding capacity to facilitate subsequent operation quickly.
The refractory less combustion chambers with different fuel holding capacity, suitable for stove operation as per users requirement. The combustion chamber consist of perforated grate at bottom to support primary air passage and series of holes of 5mm, 6mm and 6mm, in descending order with zigzag at top of combustion chamber to allow secondary air for facilitate complete combustion of all volatile gases coming our from fuel pellets. Air supply to combustion chamber is provided by air box propelled by three high speed electric fan at air inlet duct at 45° angle with speed regulator control through voltage frequency nob on hi-tech panel with additional point of connecting external battery source and having long power backup to make electricity independent operation during power failure.
A BRIEF DESCRIPTION OF THE DRAWING

Fig. 5 Combustion chamber/fuel holder

[ Number Element , Figure
1 Frame 1,2,3
2 Vessel support 1,2,3
3 Grate 1
4 Bakelite Handle 1,2,3
5 Secondary air inlet 3,4,
6 Secondary per-heated air 4
7 Preheated Secondary air 4
8 Fuel pellet 4
9 Outer cylinder 1,2,3,4
10 Middle cylinder 1,4
11 Inner cylinder 4
12 Combustion chamber 1,3,4
13 Primary air inlet 1,4
14 Fan 3,4
15 Air box 4
16 Air inlet duct 1.2,3
17 Controller 1,2,3
18 Controller support pipe 1
19 Cable pipe lock plate 2,3
20 Display 2,3
21 Castor wheel 2
22 Port & Keys 3
23 Cable pipe 2
24 Combustion chamber - 6 kg 5
25 Combustion chamber - 9 kg 5
26 Combustion chamber -15 kg 5
27 Metal Handle 1,3

FIG. 1 a schematic top view is of present stove, indicated by the arrows, to show various
internal structure.
FIG. 2 a schematic front view is of present stove, indicated by the arrows, to show various internal structure.
FIG. 3 is angle view of cooking stove, showing various of its parts, their configuration and
relationship
FIG. 4 is a longitudinal schematic view of present stove of FIG. 2 according to the present invention.
FIG. 5 is a schematic front view of combustion chamber of present stove of Fig. 1,2,3,4 according to the present invention
In accordance with a preferred embodiment of the invention as shown in the top perspective view in FIG. 1, a pellet cook stove includes an iron angle frame 1 vessel support 2, stove canopy having front top cover made of mild steel sheet, and perforated grate 3, bakelite handle 4, outer cylinder 9, middle cylinder 10, combustion chamber 12, primary air inlet 13, air inlet duct 16, controller 17, Controller support pipe 18 and metal handle 27 of combustion chamber 12 . The Fig. 2 is a front view of cooking stove, frame 1 vessel support 2, bakelite handle 4, outer cylinder 9, controller 17 with display switches 20, air inlet duct 16, cable pipe lock pipe 19, castor wheel 21 and cable pipe 23. The Fig. 3 is a angle view of cooking stove shows secondary air inlet 5 holes, ports & keys 22 on controller 17 and high speed fan 14 at air inlet duct 16 apart from parts mention in Fig. 1 & 2. The Fig 4 is a longitudinal section view of cook stove, combustion chamber 12 is cylindrical shape filled up with fuel pellets 8 having primary air inlet 13 and secondary air inlet 5 on top of the combustion chamber. Combustion chamber 12 is surrounding with preheated secondary air 7 which enter through secondary air inlet 5, these secondary preheated air 6 help in complete combustion of volatile gas generated from fuel pellet 8 during gasification in stove operation. The combustion chamber 12 is covered with outer cylinder 9 made up of stainless steel with air pocket for passive cooling, In between outer cylinder 9 and combustion chamber 12 there is middle

cylinder 10 and inner cylinder 11 made up of galvanized sheet and cavity between middle cylinder 10 and inner cylinder 11 is filled up with cerawool. The bottom of combustion chamber 12 is having grate 3 with perforated primary air inlet 13 receive air from air box 15. The air box 15 receive air from high speed electric fan 14. Fig 5 shows combustion chamber 12 having different fuel pellet 8 holding capacity, for 6 kg 24, 9 kg 25 and 15 kg 26. All combustion chamber having two metal handle 27 useful to operate combustion chamber for feeding fuel pellets or replacement with other combustion chamber in subsequent stove operation. The Fig 3 is complete view of cooking stove in accordance with the present invention, stove outer cylinder 9 contain two bakelite handle 4 for handling of stove during operation/transportation, stove cylinder covered with frame 1 with vessel support to keep cooking vessel 2. The frame 1 suitable to adjust the height between vessel support 2 and stove mouth, frame 1 is equipped with proper base to provide strong hold on surface during cooking operation. The stove outer cylinder 9 having castor wheel 21 to adjust position of stove during cooking operation. In bottom of outer cylinder 9 there is three air inlet duct 16 at 45° angle with high speed electric fan 14, all three air inlet duct 16 carry air in to air box 15 and enhance fuel combustion by entering in to combustion chamber 12 from primary air inlet 13 and secondary air inlet 5. The high speed electric fan 14 at outer side of air inlet duct 16 are connected to wire from cable pipe 23. The cable pipe 23 is connected with cable pipe lock plate 19. All three high speed electric fan 14 are connected through cable pipe 23 and controlled with hi-tech control panel 17 via remote control. The hi-tech control penal 17 is supported with pipe 18 on outer cylinder 9. The hi-tech control penal 17 contain display 20 for voltage, radio frequency, indicators of charging along with keys & port 22 for volume, and mobile charging.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is related to high efficient cook stove with refractory less combustion chamber, unique air box design for primary and secondary air supply, complete and clean

combustion of volatile gas, smoke and noise less operation, highly efficient, consume less fuel, well insulated with passive cooling, accommodate all types of fuel pellets made from virgin and processed biomass. In accordance with a preferred embodiment of the invention cook stove with feature as mention above is in cylindrical shape shell assembly and structure assembly The structure assembly contain strong an iron frame 1 with suitable color coating preferably black, frame 1 also welded with an iron strip to prepare vessel support 2 to accommodate proper distance between stove mouth to avoid frame 1 slipping during cooking operation frame 1 has strong base which provide strong grip with floor surface. The stove shell assembly is cylindrical shape with open structure on top, closed at bottom, four castor wheel 21, combustion chamber 12, three air inlet duct 16 with high speed electric fan 14, air box 15, grate 3, hi tech control panel 17 on controller support pipe 18, cable pipe 23, cable pipe lock plate 19 and two bakelite handle 4, combustion chamber with 6 kg of fuel holding capacity 24, combustion chamber with 9 kg of fuel holding capacity 25 and combustion chamber with 15 kg of fuel holding capacity 26. The stove cylinder is made up of three layer, outer layer 9 is made up of stainless steel which is stylish, corrosion resistant highly durable and good looking, middle layer 10 and inner layer 11 are made up of galvanized sheet.
Combustion chamber: The combustion chamber 12 is cylindrical shape with two metal handle 27 on top. The combustion chamber 12 is covered with middle cylinder 10 and inner cylinder 11 made up of galvanized sheet, cavity between middle cylinder 10 and inner cylinder 11 is filled up with cerawool for better insulation. The combustion chamber 12 is refractory less and made up of stainless steel, combination chamber 12 has perforated grate 3 at bottom for primary air and secondary air inlet 5 holes at top. Secondary air inlet 5 holes are in series around the combustion chamber 12, these holes are in descending order from 5 mm, 6mm and 6 mm. Combination chamber 12 receive primary air from primary air inlet 13 holes on grate 3 and secondary air from secondary air inlet 5. The combustion chamber is designed to operate on variety of fuel pellets made out of processed or virgin biomass with ash content

1 to 20 wt %, length up to 50 mm and diameter up to 10 mm. The ratio of height and diameter of combustion chamber 12 along with distribution of primary air through primary air inlet 13 and preheated secondary air through secondary air inlet 5 contribute complete combustion of volatile gas generated out of fuel pellets 8 and provide smoke less cooking operation and no blackening of vessel.
Fuel feeding: In the said invention a cooking stove is operated on fuel pellets 8, feeding of fuel is manually as per the holding capacity of combustion chamber 12, fuel pellets feeding start from grate 3 and continues up to 2 cm below from the secondary air inlet 5 holes. Fuel pellets of any quality like from any processed or virgin biomass with ash content ranging from 1 to 20 wt % length up to 50 mm and diameter up to 10 mm is suitable for cooking operation. The said invention has three different sizes combustion chamber 12 for subsequent operation of stove and for users choice. The combustion chamber 24 is designed to accommodate 6 kg of fuel pellets, combustion chamber 25 is designed to accommodate 9 kg of fuel pellets and combustion chamber 26 is designed to accommodate 15 kg of fuel pellets. Air supply: The combustion chamber 12 is cylindrical shape with two metal handle 27 on top and covered with inner 11 and middle 10 circular metal sheets. Bottom of combination chamber 12 has perforated grate 3 with primary air inlet 13 holes. Top of combustion chamber 12 has secondary air inlet 5 holes in descending order with hole size of 5mm, 6mm and 6mm in zigzag manner. The combination chamber 12 receive air from primary air inlet 13 and secondary air inlet 5. The cavity between inner 11 and middle 10 circular metal sheets is filled up with cerawool, which keeps the temperature down towards outer cylinder 9, which is low enough so no damage to the electronic devices in hi-tech control penal 17. The combustion takes place in the fire bed of combustion chamber 12 in fuel pellets 8, which make preheating of secondary air 7 pass between the cavity of combustion chamber 12 and inner cylinder 11. Main source of air supply to both primary air inlet 13 and secondary air inlet 5 is through an air box 15 propelled by three high speed electric fan 14 situated at entry of an air inlet duct 16.

Bottom of combustion chamber 12 with grate 3 is open in to air box 15 cavity, air inlet duct 16 is developed to 45° angle to the outer cylinder 9 of cooking stove. When air is propelled through this air inlet duct 16 by high speed electric fan 14, these specific arrangement create air turbulence in air box 15 cavity. In turbulence pattern primary air enter in to combustion chamber 12 through grate 3 via primary air inlet 13 and secondary air to top of combustion chamber 12 through secondary air inlet 5. The secondary air before enter in to combustion chamber get heated at secondary preheated air 6 zone between combustion chamber 12 and inner cylinder 11. The preheated secondary air 7 enter into combustion chamber 12 through secondary air inlet 5 resulting in to complete combustion of volatile gas coming from fuel pellets 8. Due to air turbulence in air box 15 resulting stove flame is up warded and bluish in color.
Operation of the present invention: The combustion chamber 12 is filled with commercial fuel pellets up to the bottom by leaving 2 cm from just below the secondary air inlet 5 holes from topside. Ignition is facilitated by spraying small amount of liquid fuel like kerosene (approx 5 -8 ml) on the surface of the fuel pellet 8. The fuel pellet is started to ignite within 4-5 minutes of time. Now place the stove under frame 1 and adjust the position by bakelite handle 4, place cooking vessel on vessel support 2. Start supply primary air from primary air inlet 13 and secondary air from secondary air inlet 5 by starring high speed electric fans 14 from on/off switch on controller 17 and monitor/controlled flame by voltage frequency nob on controller 17 to ensure fast and complete combustion which nullify blacking of vessels. Once the fuel pellets 8 starts burning, the hot volatile gases started to come from the surface. The secondary air supply from the secondary air inlet 5 holes on combustion chamber 12 and primary air from primary air inlet 13 holes on grate 3 helps to burn all volatile gases and produce bright blueish upwarded flame. The cooking stove operate at constant temperature without noise and smoke production according to the fuel capacity, the heat obtained and speed of fuel combustion can adjusted by managing air supply through fans 14 speed from

hi-tech remote control panel 17 by applying various voltage to fan by voltage regulator. The cooking stove operation can closed when all fuel pellets 8 convert into ash. To start the new operation, remove empty hot combustion chamber 12 by handle 27 and place new combustion chamber 12 filled with fuel pellets as per requirement, either combustion chamber with 6 kg of fuel holding capacity 24 or combustion chamber with 9 kg of fuel holding capacity 25 or combustion chamber with 15 kg of fuel holding capacity 26. Well insulated stove body with cerawool in between inner cylinder 11 and middle cylinder 10 do not allow heat to disperse in to cooking area which facilitate smooth cooking operation with no harm on control panel 17 and other electric parts like fans 14, passive cooling pockets on outer layer of stove make comfort handling of stove while operation. After subsequent operation generated ash from fuel combustion can be removed by manually by removing combustion chamber 12 or from air inlet duct 16. The control panel 17 is having display panel with charging indicator, USB port for mobile charging and music, voltage regulator, battery for backup with additional point for connecting external battery source. Long power backup facilitate stove operation even in rural area where electricity is not available and provide uninterrupted operation during power failure. Stove with castor wheel 21 and separate vessel frame 1 enhance versatile cooking operation like frying, backing, steaming, roasting, boiling etc.
Electronic part: An electrical cord is provided to connect the stove hi-tech control panel 17 to the mains 220 V, single phase supply. The 220V supply is stepped down to 24V through a 24V step down transformer which is provided in the control panel box 17. The output of the transformer is given to high speed electric fan 14 switch and display on controller 17. Integrated battery with long power backup is provided to operate stove with equal efficiency in case of electric supply is not present.

WE CLAIM
1. A high efficiency solid biofuel pellet cooking stove comprising,
a. a stove structure with frame for cooking vessel
b. a combustion chamber
c. an integrated air circulation system through air box
d. Panel with mechanism for speed variation with voltage control, voltage display
with charging indicator, in-built battery backup, radio player with channel & volume
keys, USB port for mobile charging and music, and additional point for connecting
external battery source
e. a global design integrating passive cooling, occupational safety, with leakage proof
insulation, complete fuel combustion, smokeless, noise less, regulated air supply,
sufficient integrated power back up, interchangeable combustion chamber of 6 kg - 20
kg fuel holding capacity with metal handle, separate vessels holding structure,
compatible stove design for all types of fuel pellets.
2. The high efficient stove as claimed in claim 1, consists of combustion system, insulated
body, castor wheel, separate vessel holding stand, high speed electric fans with voltage control and power backup system.
3. The combustion chamber as claimed in claim 1, is refractory less, cylindrical shape with
perforated grate at bottom and series of 5mm, 6mm and 6mm holes on top in zigzag pattern.
4. The body of high efficiency cooking stove as claimed in claim 1, consists of double layered
wall of galvanized sheet with outer covering of stainless steel, two bakelite handle, three air inlet duct with high speed electric fan, four castor wheel, cable pipe, cable pipe lock plate and control panel support arrangement
5. The air circulation in high efficiency cook stove as claimed in claim 1, air turbulence from
high speed electric fan from air inlet duct at 45° angle in air box for supply of primary

and secondary air to combustion chamber.
6. The high efficiency cook stove as claimed in claim 1 is feed by fuel pellets made from all
types of processed or virgin biomass from wood, wood reside, forest left over, grasses, saw dust, agricultural residue, process industry waste with ash content 1 to 20 wt %, length up to 50 mm, diameter up to 10 mm.
7. The body of high efficiency cooking stove as claim in claim 1, consist cerawool as insulating
i
materiel between inner and middle layer.
8. The high efficiency solid biofuel pellet cook stove as claimed in claim 1, easily transportable
with four rollers and two bakelite handles on outer body and a removable combustion chamber with adaptive shape handle on top.
9. The high efficiency cook stove as claimed in claim 1 is suitable for all types of cooking like;
frying, backing, steaming, roasting, boiling with noise less operation, smoke less operation and no blackening of vessel
10. A high efficiency solid biofuel pellet stove as herein described with reference to foregoing
drawings.