A CLEAN BURNING COOKSTOVE DEVELOPED IN VIETNAM

by Alexis Belonio, Tran Binh, Doan Thi Minh Nguyet, and Bui Dinh Hai

Vietnam is producing a lot of biomass, such
as agricultural and forest residues, annually
amounting to about 7 to 8 and 75 to 100
million metric tons, respectively.  The
country’s pressing need for a low‐cost fuel
and a clean‐burning cook stove has led
VINASILIC to develop, in early 2009, a new
generation cooking technology that is
suitable for Vietnamese households.
Adopting the TLUD principle for the stove,
combined with the use of torrefied biomass
pellets as fuel for the stove, enable
VINASILIC to produce a biomass gas stove
that emits blue flame, shown in right photo,
with very low black carbon emission (less
than 50 ug/m
3
).
The stove, as shown in the above photo,
consists of a cylindrical reactor, an outer
cylinder, a gas burner, and a fan.  The
cylindrical reactor is where the fuel is
gasified.  It is provided
with grate at the bottom
for the passage of
primary air.  The outer
cylinder serves as stove
body and as burner
support.  The gas burner
is where the gas
generated from the
reactor, mixed with
preheated air, is ignited.
The fan is attached to
the stove body and is
used to supply the air
needed for gasification.
The stove is made of a
metal sheet, an earthen
ware and an ash
insulation to prevent
escape of heat through
the surface of the stove
body.  The primary air
enters from the bottom
end of the reactor with
the use of a 0.15‐Amp, 12‐
V DC fan.  The secondary
air, on the other hand,
enters the reactor through
the holes in the middle of
the stove body and is
mixed with the gas
generated at the small
holes located at the upper
portion of the burner.  A
skirt is sometimes
provided for the stove to
increase heat transfer
efficiency to the cooking
pot.
The stove comes in different sizes, as shown in Table 1 below.  Sizes 1 and 2 are for cooking
soup.   Sizes 3 to 5 are the standard cooking stove; whereas, size 6 is for cooking noodles.
As shown, the reactor diameter varies from 11.5 to 21.0 cm and the height varies from 9 to
36 cm.  The stove reactor can accommodate 0.17 kg of fuel for the smallest unit while 3.15
kg for the biggest.  The fuel can be ignited to produce combustible gases within 3 to 8
minutes, depending on the size of the stove.  Operating time is quite longer of about 50 to
75 minutes for the small stove while 180 to 240 minutes for the big stove.  Thermal
efficiency varies from 26 to 30%.  The computed power output ranges from 0.25 kW for the
small stove and 2.0 kW for the big stove.   On the average, the stove takes less than 5
minutes to boil a liter of water.  Other test results also show that one kilogram of rice husk
pellets can boil 18 liters within  45 minutes.  The temperature of the flame, measured using
infrared thermometer, varies from 280 to 350°C.
Table 1.  Design and Performance  of the Stove.
Size  Reactor
Diameter
(cm)
Reactor
Height
(cm)
Fuel
Capacity
(kg)
Start Up
Time
(min)
Operating
Time
(min)
Thermal
Efficiency
(%)
Power
Output
(kW)
1  11.5  9.0  0.17  3  50‐75  26  0.25
2  12.0  20.0  0.30  4  60‐90  26  0.35
3  12.0  20.0  0.47  4  75‐90  28  0.60
4  14.0  24.0  0.8  5  90‐120  30  0.90
5  16.0  30.0  1.5  5  120‐180  30  1.25
6  21.0  36.0  3.15  8  180‐240  30  2.00

The advantage features of the stove are: (a) No
smoke during operation, (b) No toxic gases are
emitted from the burning flame, (c) Easy to ignite
fuel, (d) Convenient to use and cooks food faster,
(e) Easy to adjust cooking to the user’s
requirements, (f) High efficiency, which save
much  fuel, and (g) Low investment cost.
The stove uses torrefied biomass from
agricultural and forest wastes, together with
coal.  The fuel is pelleted to have uniform sizes.
A kilo of torrefied biomass pellets can supply
gaseous fuel for more than one‐hour cooking.
The stove is locally fabricated and is named as
“Vietnam Magic Flame” Stove.  It is sold at US$
10 to 15 per unit.  The biomass pellets, which are also developed and produced by
VINASILIC, cost US$ 0.12 to 0.15 per kg.  Compared with kerosene and LPG, the payback
period for the stove is within 6 months.  Moreover, VINASILIC has already started the
promotion of the stove in Vietnam and will start its commercialization of the stove and the
fuel soon to benefit the people.
For further information, please contact Professor Tran Binh (tranbinhshc@gmail.com),
VINASILIC SJ, Socialist Republic of Vietnam or Alexis Belonio, Center for Rice Husk Energy,
Philippines (atbelonio@yahoo.com).


Released:  January 20, 2010