Performance Improvement Of Self-Aspirating Porous Radiant Burner By Controlling Process Parameters

Bibhuti B. Samantaray et al. Int. Journal of Engineering Research and Application www.ijera.com
ISSN : 2248-9622, Vol. 3, Issue 5, Sep-Oct 2013, pp.978-984
www.ijera.com 978 | P a g e
Performance Improvement Of Self-Aspirating Porous Radiant
Burner By Controlling Process Parameters
Purna C. Mishra*, Bibhuti B. Samantaray*, Premananda Pradhan**, Rajeswari
Chaini*, Durga P. Ghosh*
*(School of Mechanical Engineering, KIIT University, Bhubaneswar-24)
** (Institute of Technical and Research, S’O’A University, Bhubaneswar-30)
ABSTRACT
This paper presents the heat transfer characteristics of a self-aspirating porous radiant burner (SAPRB) that
operates on the basis of an effective energy conversion method between flowing gas enthalpy and thermal
radiation. The temperature field at various flame zones was measured experimentally by the help of both FLUKE
IR camera and K-type thermocouples. The experimental setup consisted of a two layered domestic cooking
burner, a flexible test stand attached with six K-type thermocouples at different positions, IR camera, LPG setup
and a hot wire anemometer. The two layered SAPRB consisted of a combustion zone and a preheating zone.
Time dependent temperature history from thermocouples at various flame zones were acquired by using a data
acquisition system and the temperature profiles were analyzed in the ZAILA application software environments.
In the other hand the IR graphs were captured by FLUKE IR camera and the thermographs were analyzed in the
SMARTView software environments. The experimental results revealed that the homogeneous porous media, in
addition to its convective heat exchange with the gas, might absorb, emit, and scatter thermal radiation. The rate
of heat transfer was more at the center of the burner where a combined effect of both convection & radiation
might be realized. The maximum thermal efficiency was found to be 64% which was having a good agreement
with the previous data in the open literature.
Keywords - IR Thermography, LPG, Self-Aspirating Porous Radiant Burner (SAPRB), Thermal Efficiency,
Transient Temperature.
Nomenclature
AV Surface Area Density
V Gas Velocity, m/s
∅f Porosity
d Hydraulic Diameter, m
Nu Local Nusselt Number
Re Reynolds Number
H Local Heat Transfer Co-efficient, W/m2
k
ρ Mass Density of LPG, kg/m3
mw Mass of Water, kg
mv Mass of Vessel, kg
mf Mass of Fuel, kg
Cpw Specific heat of aluminum, kJ/kg K
Cpv Specific heat of aluminum, kJ/kg K
CV Calorific value of the fuel, kJ/kg
T1 Initial Temperature of Water, ℃
T2 Final Temperature of Water, ℃
I. Introduction
The heating systems used for domestic
purposes that operate on free flame, leads to relatively
low thermal efficiency. A lot of previous works are
available on the use of porous media in direction of
increasing thermal efficiency. Energy conversion
aspects between flowing gas enthalpy and thermal
radiation by using porous medium becomes an
interesting approach for improving the overall
performance of these systems. Proper parametric
control may lead to better enhancement of burner
performance. In India, LPG (liquefied petroleum gas)
is the most commonly used conventional fuel [1].So as
it is common in other Asian countries also. As the
economy of the country is getting better day by day so
as the standard of living of the people. The population
of the India is approximately 1.25 billion so as the
LPG market is very huge. Government of India is
spending huge amount of money for subsidizing the
domestic LPG cylinder price [2]. As it is a burden on
the Government & ultimately on the people, different
ways should be invented to increase the thermal
efficiency of the conventional burners. N.K. Mishra et
al. [3] has tested Medium-Scale (5-10 kW) Porous
Radiant Burners for LPG Cooking Applications with a
good effect. He found the PRB with 5kw thermal load
yielded the maximum thermal efficiency of about 50%,
which is 25% higher than the efficiency of the
conventional burner also the emission are much lower
than the conventional burner. V.K Pantangi et al. [4]
has studied the porous radiant burner for LPG cooking
application. In his study he found that the maximum
thermal efficiency of PRB is found to be 68% which is
3% higher than the conventional burner with less CO
& NOX emission. P.Muthukumar & P.I Shyamkumar
[5] developed a novel porous radiant burner for LPG
cooking applications. They have tested PRB having
different porosity with different equivalence ratio &
RESEARCH ARTICLE OPEN ACCESS

wattages. The reported maximum thermal efficiency is
about 75% which is 10% higher than the conventional
burners. S.B Sathe et al. [6] has studied both
theoretically & experimentally the thermal
performance of the PRB. The results indicate that
stable combustion at elevated flame speeds can be
maintained in two different spatial domains: one
spanning the upstream half of the porous region and
the other in a narrow region near the exit plane. The
heat release and radiant output are also found to
increase as the flame is shifted toward the middle of
the porous layer. Akbari et al. [7] carried out a study to
investigate the lean flammability limits of the burner
and the unstable flash-back/blow-out phenomena.
Hayashi et al. [8] presented a three-dimensional
numerical study of a two-layer porous burner for
household applications. They solved the mathematical
model using CFD techniques which accounted for
radiative heat transport in the solid, convective heat
exchange between solid and fluid. Talukdar et al. [9]
presented the heat transfer analysis of a 2-D
rectangular porous radiant burner. Combustion in the
porous medium was modeled as a spatially-dependent
heat generation zone. A 2-D rectangular porous burner
was investigated by Mishra et al. [10]. Methane–air
combustion with detailed chemical kinetics was used
to model the combustion part. S.W Cho et al. [11] has
experimentally studied the performance optimization
of a radiant burner with a surface flame structure. The
experiment was conducted in three different firing
rates (80.5, 107.4 and 134.2 kW/m2
) and different
equivalence ratios ranged from 0.6 to 1.3. In his study
the firing rate of 107.4 kW/m2
was regarded as an
optimal condition and water-boiling efficiency was
found to be 40%.Sharma et al. [12] investigated the
effect of porous radiant inserts in conventional
kerosene pressure stove. The found that using porous
insert, the efficiency of the conventional stove
increases from 55% to 62%. Sharma et al. [13]
modified conventional kerosene pressure stove. They
used ceramic (ZrO2) insert in the combustion zone and
a ceramic (Al2O3) heat shield surrounding the burner.
The maximum efficiency was found to be 70%, which
was 15% higher than the efficiency of a conventional
kerosene pressure stove. S. Wood and A.T Harris [14]
have studied on porous burners for lean burn
applications. In this paper, we attempted to find out
thermal performance of a self-aspirant porous radiant
burner by controlling its process parameters.
II. Experimental Set Up and Procedure
A schematic of the experimental set-up used
for testing the performance of PRB is shown in Fig.1.
The experimental setup is a flexible one and it consists
of a LPG setup, a hot wire anemometer, a burner, 6 k-
type thermocouple, a data acquisition system, an IR
camera and a computer. The LPG setup supplies the
fuel through a Teflon pipe of 0.6 mm diameter. The
gas passes through the hot wire anemometer with
suitable control valves which measures the flowing gas
velocities. The air and fuel mixtures are tested at
different velocities. The two layered SAPRB consists
of a preheating zone & a combustion zone.
Combustion zone was formed with high porosity,
highly radiating porous matrix, and the preheating
zone consisted of low porosity matrix. Three k-type
thermocouples as thermocouple-1, thermocouple-2 and
thermocouple-3 are arranged in vertical manner i.e.
respectively 28mm, 64mm and 115 mm away from the
surface of the burner and the other three thermocouples
as thermocouple-4, thermocouple-5 and thermocouple-
6 are arranged in horizontal manner i.e. respectively
12mm, 35mm and 25mm away from the center of the
burner, which is having a radius of 38mm. All the
thermocouples are connected to the data acquisition
system which is also connected to a computer for live
data analysis. In the meantime all the radiative
temperatures of the surface and the flame is being
measured by the Fluke IR camera. The temperature
profiles of data acquisition system were analyzed in
the ZAILA application software environments. In the
other hand the thermographs were analyzed in the
SMARTView software environments. The whole
experimental procedure has been conducted in a very
controlled condition. The gas velocity was measured
by the hot wire anemometer. It was positioned just at
the exit of the nozzle.
Figure.1. Schematic of the experimental setup
A sample of thermocouple arrangement on the
plate is shown in the following.

Figure.2: Sketch of thermocouple arrangement
The experimented was conducted in three
different velocities viz. 3.6 m/s, 3.0 m/s and 0.4 m/s.
Then the temperature data are measured by the
thermocouple which has been arranged both in
vertically and horizontally on the top surface of the
burner. The temperature data are assessed by the data
acquisition system. The temperature data are assessed
by the data acquisition system. Also the surface and
flame temperature are measured by IR camera. Then
the heat transfer co-efficient h, was calculated by the
following co-relation [15].
0.35
e0.95RuN  (1)
Re
f Vd

 (2)
III. Results and Discussion
We have conduct the experiment in three
different gas velocities i.e. 3.6 m/s, 3.0 m/s, 0.4 m/s.
So the time dependent temperature graphs are
mentioned in the Fig.3-14. Also the IR thermograph is
shown in Fig. 17.
3.1 Effect of Heat Transfer at Maximum Gas
Velocity
Fig.3 and Fig.4 shows the time dependent
temperature histories of the vertical and horizontal
arranged thermocouples respectively at gas velocity
3.6 m/s. From the Fig.3 the maximum temperature
attained is 1247℃ by thermocouple-3.
Figure-3. Time dependent temperature distribution of
burner (vertical at v= 3.6 m/s)
burner (horizontal at v= 3.6 m/s)
burner (vertical at v = 3.0 m/s).

burner (vertical at v= 0.4 m/s)
Figure-9. Temperature-time graph of t-1(vertical) at
variable gas velocity

Figure-12. Temperature-time graph of t-4(horizontal)
at variable gas velocity
Figure-15. Gas velocity-Thermal efficiency graph
Figure-16. Gas velocity-Heat transfer co-efficient
graph.
Figure-17. IR thermograph of SAPRB at v=3.6m/s.
It attains the maximum temperature because
in this zone both convection and radiation heat transfer
might be realized. Similarly from Fig. 4 the maximum
temperature attained is 969℃. It attains the maximum
temperature in that zone because it was very close to
the center of the burner and the convection heat
transfer is maximum whereas the radiation heat loss is
minimum. By calculating, the local heat transfer

coefficient h, at gas velocity 3.6m/s is found to be 5.64
W/m2
k.
3.2. Effect of Heat Transfer at Average Gas
Velocity
3.0 m/s. From the Fig. 5 the maximum temperature
attained is 970℃ by thermocouple-3. It attains the
maximum temperature because in this zone both
convection and radiation heat transfer occurs. Similarly
from Fig.6 the maximum temperature attained is
946℃. It attains the maximum temperature because it
was very close to the center of the burner and the
convection heat transfer is maximum whereas the
radiation heat loss is minimum. By calculating the
local heat transfer coefficient h, at gas velocity 3.0m/s
is found to be 5.29 W/m2
k.
3.3. Effect of Heat Transfer at Minimum Possible
Gas Velocity
0.4 m/s. This is the minimum velocity where the
combustion could possible in this experimental
apparatus. From the Fig.7 the maximum temperature
attained is 315℃ by thermocouple-3. It attains the
maximum temperature because in this zone both
convection and radiation heat transfer takes place.
Though the thermocouple 1 and 2 are close to the
surface but they could not attain that much of
temperature like thermocouple-3.Similarly from Fig.8
the maximum temperature attained is 710℃. It attains
the maximum temperature among all the
thermocouples in the minimum gas velocity because it
was very close to the center of the burner and the
convection heat transfer is maximum whereas the
radiation heat loss is minimum. By calculating the
local heat transfer coefficient h, at gas velocity 0.4m/s
is found to be 2.61 W/m2
k. From the above facts it is
clear that the convective heat transfer is the
predominantly mode of heat transfer and the radiation
heat transfer lends the required support to it. The
radiation heat transfer is more when the gas velocity is
more and vice-versa is also true.
3.4 Transient Temperature Measurement
Fig.9-14 shows the time dependent
temperature graphs of a single thermocouple
(horizontal or vertical) with different velocities. From
the graph we conclude that, vertically & horizontally
the rate of heat transfer increases with increase in gas
velocity and vice versa. But the notable factor is the
thermocouple-4 attains the temperature about 703℃
with the minimum gas velocity 0.4m/s. So it indicates
that the rate of heat transfer is more in that zone where
both convection and radiation heat transfer may be
realized.
3.5. Calculation of Heat Transfer Co-efficient (h).
The following “Table” contains the calculated
values of Re, Nu and h form the “equation (1)”.
Gas
Velocity
3.6 m/s 3.0 m/s 0.4 m/s
Re 0.0524 0.0437 0.0058
Nu 0.3384 0.3176 0.1566
h 5.64 w/m2
k 5.29 w/m2
k 2.61 w/m2
k
3.6. Thermal Efficiency Calculation
The percentage of thermal efficiency η of
burner is estimated based on following formula [5].
η =
2 1( )( )w pw v pv
f
m c m c T T
m CV
 
(3)
Where, mw and mv are the masses of water
and vessel and mf are the mass of the fuel consumed
during experiment. The calorific value of the fuel (CV)
is 45780 kJ/kg. Specific heats of aluminum and water
are Cpv = 0.8959 kJ/kg K and Cpw = 4.1826 kJ/kg K,
respectively. By calculating the thermal efficiency of
the burner is found to be 64.16% at gas velocity 3.6
m/s, 55.46% at gas velocity 3.0 m/s and 36.52% at gas
velocity 0.4 m/s. So the maximum thermal efficiency
obtained in this experiment is 64.16% which is very
good considering the main focus of this experiment
was process optimization instead of other aspects.
IV. Conclusion
- The performance of SAPRB was analyzed
experimentally to realize the effects of various
controlling parameters.
- The thermal efficiency of SAPRB was computed
up to 64 % which showed a good agreement with
the previous works.
- The controlling parameters such as gas velocity,
nozzle exit to the burner distance were critically
varied to realize the convection heat transfer from
the burner surface and flame.
- K-type thermocouples were used to measure the
transient local temperature distribution and
FLUKE IR thermography confirmed the radiation
dominancy.
- It was confirmed that the overall thermal
efficiency of SAPRB can be enhanced by
optimizing the controlling process parameters
even though the design is not modified.
References
[1] D’Sa Antonette, N Murthy, 2004.Report on
the use of LPG as a domestic cooking fuel
option in India. Int. Energy Initiative,
http://www.iei-asia.org/ IEIBLR-LPG
Indiahomes.Report.pdf.

[2] Mnril R. LPG in India subsidy with a
purpose, In: WLPGA – North Africa LPG
summit 20th May 2010.
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Performance Tests on Medium-Scale Porous
Radiant Burners for LPG Cooking
Applications, International Journal of
Emerging Technology and Advanced
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ISSN 2250-2459.
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Performance Improvement Of Self-Aspirating Porous Radiant Burner By Controlling Process Parameters

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