Field of Invention:
The present invention to a energy efficient kerosene based room heater, 'Bukhari' which derives its name from 'Bukhar' the Urdu word for high temperature. Bukhari is widely used by inhabitants of the Himalayan foothills and defence and paramilitary personnel guarding the national frontiers at high altitude and cold climatic areas.
Indian Oil R&D Centre has been doing R&D work for the development of energy efficient appliances with a view to conserve petroleum products. Earlier the Applicants herein have developed energy efficient Nutan wick stove, Nutan LPG Stove, Nutan hurricane Lantern, Nutan Wick Lamp, LPG commercial burner and Nutan Himveer Bukhari. Now, the Applicants have developed kerosene based Bukhari with a view to make it portable.
Background;
The two versions of conventional Bukharis, being used are mentioned below:
Bukhari with Flue Gas Exhaust
This category of Bukhari has a high burning rate and is provided with draught facility for flue gas escape. In this type of Bukhari, combustion of fuel takes place either by means of a hot plate in the combustion chamber which cracks the fuel and burns to produce heat or by means of wick. The fuel, supplied from outside storage, is either made to fall on the hot plate or supplied to the wick through regulatory system. The heat produced is used for heating the combustion chamber, which in turn radiates the heat to the room. Our earlier developed Nutan Himveer Bukhari is of this category.
Bukhari without Flue Gas Exhaust
This type of Bukhari has capacities varying between 1-5 KW with different sizes of fuel tanks and burners. Its fuel tank is provided with burners, which burn kerosene with the help of incombustible wick. The heat produced, radiates through a reflector or burner enclosure provided in the Bukhari. Since the chimney is not attached with this type of Bukhari they become portable and can be easily taken from one room to another
room. They are meant for short duration use due to their limited tank capacities and absence of flue gas exhaust system. The specification describes the features of this category of bukhari.
Prior Art:
Burner of Japanese bukhari is made of four sleeves- inner three perforated sleeves and outer one unperforated. Innermost sleeve has steeped cylindrical shape with smaller diameter on the top and bigger on the bottom. In the middle stepped portion of the innermost sleeve, a circular perforated plate is placed. Height of the inner sleeve is more as compared to the outer sleeves. The inner sleeve is covered with an unperforated top cover plate with its outer edge protruding outside. Rest three sleeves including outer unperforated sleeves are covered with a steeped tapered unperforated top cover plate. The incombustible wick is installed between the inner second and third perforated sleeves.
Primary air enters into the innermost sleeves from the hole provided at the centre in the fuel tank. Some amount of primary air and secondary air enters into the burner thru' outer burner casing having vertical slots at the top and bottom. With the help
of this primary and secondary air, kerosene oil sucked thru' incombustible wick burns and give flame. The color of the flame is little yellowish. The burning flame heats the outer burner casing which radiates heat into the room.
In Korean type Bukharis the burner is made of four perforated sleeves. The inner sleeve is smallest in height and diameter. 2nd inner sleeve has steeped cylindrical shape with smaller diameter on the top and bigger on the bottom. In the middle stepped portion of the 2nd inner sleeve, a circular perforated plate is placed. Inner second sleeve is covered with top unperforated cover since innermost sleeve is smallest in height it is also covered with the same top cover plate. Outer two sleeves are covered with a separate unperforated top cover ring plate. The incombustible wick is installed between the second and third perforated sleeves. Another model of Korean type of Bukharis is having a reflector for heat radiation to one side only.
Provision of primary and secondary air intake of Korean type bukhari is similar to that of Japanse bukhari.
In both the above bukharis lifting and lowering of wick is done through rack and pinion mechanism. In addition to the rack and pinion mechanism for wick lifting, there is a spring loaded ratchet mechanism for automatic releasing of wick to its lowest position for quick extinction of flame. Moreover, there is a provision of wick ignition through a battery operated lighter in addition to manual ignition of wick through kindler.
Objective of the invention:
The main objective of the present invention is to provide a portable bukhari with high heat output.
Another objective of the present invention is to provide high heat output at lower kerosene consumption rate with improved performance efficiency.Another objectives is to provide ease of maintenance and user friendliness.
Description of Drawings
Figure 1: Fuel container with Wick lifting device
Figure 2: Burner sleeves
Figure 3: Outer casing
Figure 4: Humidifier
Figure 5: Assembled Bukhari
Figure 6: Cross sectional view of Bukhari
Description of above figures describing all the components of the bukhari and their inter-connectivity has been given below under heading Description of invention.
Description of the invention
The above objectives have been achieved through improved kerosene burning and innovative design of burner and other components of Bukhari.
The invented portable room heater consists of fuel container, wick lifting device, four walled burner sleeves, outer casing and top cover plate. The salient features of different parts of the portable bukhari are mentioned below:
Fuel Tank(1):
It is made of metal sheet and has a capacity of 7.5 liters for kerosene fuel. The fuel container is hollow, stepped and cylindrical in shape. It has a hole in centre(2) to provide primary air to burner for improved combustion of kerosene. Specially designed fins((13) are provided on the inner side of the central hole(2) to keep the temperature of kerosene fuel under control. The fins(13) are covered with a metal sheet sleeve called fins sleeve (14) having stepped in shape at its top. This fins sleeve(14) helps in providing cooling affect to the fins thru the primary air being sucked from the bottom of the fuel tank(l). This primary air going thru' fins(13) gets preheated and mixes with fuel giving better combustion. The inner sleeve(7) sits on the stepped covered portion of fins sleeve(14). The central hole(2) of fuel tank(l) has a stepped top portion which provides seating base for 2nd inner sleeve(8). The incombustible flat wick (4)remains dipped in the kerosene kept in the fuel tank(l). Only three fourth of its capacity is required to be filled with kerosene fuel
Burner:
Burner of the innovated bukhari consists of four sleeves (7, 8, 9, 10) of longer height and diameter as compared to conventional available portable bukharis. These four sleeves are fastened with the help of two cross bars(11). Innermost sleeve(7) is perforated at bottom portion only having two rows of perforations of diameter 2.5 mm with horizontal pitch of 12mm (horizontal distance between centre to centre of two perforations) and vertical pitch of 8mm pitch (vertical distance between centre to centre of two perforations) in zig-zag pattern whereas 2nd inner sleeve(8) is perforated from bottom to top with perforation size varying from bottom to top i.e. (1.5 to 1.7 mm diameter,, 6.4 to 6.6 mm horizontal pitch, 6.4 to 6.6 vertical pitch) for the first ten rows, (1.7 to 1.8 mm diameter, 4.9 to 5.1 mm horizontal pitch, 4.9 to 5.1 mm vertical pitch) for the subsequent ten rows and (1.8 to 2.0 mm diameter, 4.9 to 5.1 mm horizontal pitch, 4.9 to 5.1mm vertical pitch) for the rest of rows of the perforations and 3rd inner sleeve is perforated with perforations of 1.5 to 1.7 mm diameter size and have 4.9 to 5.1mm each horizontal and vertical pitch. The second and third inner sleeves(8, 9) are perforated throughout their length. Outer sleeve(lO) is
unperforated. The perforations in the sleeves have been optimised for suction of sufficient air. The inner and 2nd inner sleeves (7, 8) are covered with a top cover plate(17) having perforations of 6.9 to 7.1 mm diameter on the outer periphery whereas the 3rd inner sleeve and outer sleeves(9, 10) are covered with a separate top cover ring plate(18) having one row of perforations of 6.9 to 7.1mm diameter. The height of inner and 2nd inner sleeves(7, 8) is lower than outer two sleeves(9, 10) which help in proper combustion of fuel. These sleeves help in generating optimized air/fuel mixture for efficient combustion of kerosene fuel with blue flame.
Wick lifting device (5):
Wick lifting device(5) is made of Metal sheet. It consists of rack and pinion mechanism for the upward and downward movement of the round incombustible wick(4). The top stepped portion of wick lifting device(5) provides seat for 3rd inner sleeve(9). The round incombustible wick(4) lies between the 2nd and 3rd inner sleeves(8, 9). The wick(4) is installed in between the inner periphery of the wick lifting device(5) and outer periphery of
cylindrical part of the central hole(3) of fuel tank(l). The kerosene oil is sucked thru' the wick by capillary action.
Outer Casing(21):
Outer casing(21) is a hollow cylindrical metal part which helps in heat radiation to the room where the bukhari is operated. There are horizontal slots(20) in the bottom and top to provide primary and secondary air for combustion. There is also provision of a window(19) for kindling the wick(4). The outer casing(21) along with top cover plate(22) provide stable flame and thus help in efficient combustion. It also helps in safe operation of Bukhari and provide safety. For additional safety a safety wire mesh guard(16) is also provided. A handle(16) has been provided to carry the bukhari from one place to another place. The top cover plate(22) of outer casing(21) can be used for heating small quantity of water and other things.
Humidifier(12):
It is a metallic plate above which the bukhari is placed containing some water to keep the room properly humidified to avoid the air dryness.
Performance of invented portable Bukhari:
Performance evaluation was carried out for three hours starting at ambient temperature in a specially set-up laboratory. The result obtained is given below
.(Table Removed)
The invented Bukhari is found giving blue flame whereas other conventional portable bukhari give yellow flame. Blue flame is the
indication of improved combustion of kerosene fuel. It resulted in giving higher heat output with higher room temperature and 20% more performance efficiency as compared to traditional portable Bukharis.

We claim:
1. Energy efficient kerosene based portable Room Heater (Bukhari) comprising a cylindrical fuel tank(l) made up of metal sheet having a hole(2) in the centre to provide primary air to burner for improved combustion of kerosene, and a incombustible flat wick(4) dipped in kerosene in the fuel tank(l),a burner having three inner sleeves(7, 8, 9) and one outer sleeve(lO) fastened with two cross bars(ll), said incombustible flat wick(4) positioned between the second inner and third inner sleeves(8, 9),
a wick lifting device(5) made up of metal sheet to control the temperature of said heater, said device having rack and pinion mechanism for the upward and downward movement of said wick(4), the wick being positioned between the inner periphery of cylindrical part of the central hole(3) of the said fuel tank(l),
a outer casing (21) made up of metal sheet for spreading of emitted heat radiation, said outer casing having horizontal slots(20) in the bottom and top to provide primary and secondary air for combustion, a window(19) for kindling the said wick(4), a safety wire mesh guard(16) for additional safety during the handling, a handle(15) to carry the said heater (bukhari) from one place to another, Characterized in that:
said central hole(2) has fins(13), fins(13) being covered with a fin sleeve(14) having stepped in shape at its top to keep the temperature of said fuel tank(l) under control, and primary air that comes from said central hole(2) at the bottom of the said fuel tank (l)moves through the slots between the fins(13) and fin sleeve(14) thereby providing preheating of air for improved combustion efficiency of the fuel,
wherein innermost sleeve(7) is perforated at bottom portion only whereas second inner and third inner sleeves(8, 9) are perforated throughout their length with optimized perforations by giving different size of perforation at bottom and top of the sleeves for suction of sufficient air and outer sleeve(10) is unperforated,
said innermost and second inner sleeves(7, 8) are covered with top cover plate(17) whereas the third inner sleeve and outer sleeve(9, 10) are covered with a separate top cover ring plate(18) having one row of perforations of optimized size for the complete combustion of fuel, the height of said innermost and second inner sleeves(7, 8) being lower than outer two sleeves(9, 10) for proper combustion of fuel by generating optimized air-fuel mixture resulting into a blue flame;
wherein said bukhari is placed on a humidifier(12) which is a metallic plate containing some water to keep the room properly humidified to avoid the air dryness.
2. Room heater as claimed in claim 1, wherein said inner most sleeve(7) of burner has two rows of perforations of diameter 2.4 to 2.6 mm with horizontal pitch of 11.9 to 12.1mm (horizontal distance between centre to centre of two perforations) and vertical pitch of 7.9 to 8.1mm pitch
(vertical distance between centre to centre of two perforations) in zig-zag pattern at the bottom portion.
3. Room heater as claimed in claim 1, wherein said second
inner sleeve(8) of burner is perforated from bottom to top
with perforation size varying from bottom to top i.e. (1.5 to
1.7 mm diameter,, 6.4 to 6.6 mm horizontal pitch, 6.4 to 6.6
vertical pitch) for the first ten rows, (1.7 to 1.8 mm diameter,
4.9 to 5.1 mm horizontal pitch, 4.9 to 5.1mm vertical pitch)
for the subsequent ten rows and (1.8 to 2.0 mm diameter, 4.9
to 5.1 mm horizontal pitch, 4.9 to 5.1mm vertical pitch) for
the rest of rows of the perforations.
4. Room heater as claimed in claim 1, wherein said third inner
sleeve(9) of burner is perforated with perforations of 1.5 to
1.7 mm diameter size and have 4.9 to 5.1mm each horizontal
and vertical pitch.
5. Room heater as claimed in claim 1, wherein said top cover
plate (17) of the inner most sleeve and second inner sleeve
(7, 8) has one row of perforations of 6.9 to 7.1mm diameter
at the outer periphery.
6. Room heater as claimed in claim 1, wherein said top cover
ring plate(18) of the third inner sleeve and outer sleeve(9, 10)
has one row of perforations of 6.9 to 7.1mm diameter.
7. Room heater as claimed in claim 1 wherein said room heater
rises the temperature of 18 to 20°C within 3 hours and has
kerosene consumption rate of 20 g/h/ °C for per 1°C degree
rise in room temperature.
8. Energy efficient kerosene based portable Room Heater
(Bukhari) substantially as herein described with reference to
the foregoing description and the accompanying drawings.