ELECTRICAL CONTROL OF COMBUSTION
Researchers:
Dr.phys. Maija ZAKE <mzfi@sal.lv>
Research assistant Inesa Barmina <mzfi@sal.lv>
Eng. Modris PURMALS <mzfi@sal.lv>
The
scope of our researches include experimental laboratory and industrial
investigations of the electric field effect on the processes of heat and mass
transfer and fuel combustion in the flame flows with the aim to develop
electrical control of fuel combustion and the levels of NOx and CO2
emissions in pollutants.
The
preliminary phase of these researches involved the experimental investigations
of the radial electric field effect on the processes in a free propane-air
flame flow and profound field effect on the flame structure had been observed
(Fig.1).
|
|
|
U=-3kV |
U=0 |
U=+3kV |
Fig.1.
The radial electric field effect on the flame structure |
Effects examined in a free flame flow include:
· The
radial electric field effect on the flame composition profiles;
· The
radial electric field effect on the temperature profiles;
· The
radial electric field effect on the flame radiation profiles.
The
next stage of these researches involved the experimental investigations of the
radial electric field effects on the processes in the flame channel flows with
the aim of achieving electric control of NOx and CO2
emissions.
The
experimental investigations are carried out using sectioned water-cooled
channel. The radial DC electric field is applied to the flame channel flow
between the channel walls and negatively or positively biased central
electrode, which is aligned along the channel (Fig.2). The flame flow from the
water-cooled channel enters a quartz tube of length 500mm, which promotes
progression of fuel combustion along the tube.
The radial and axial temperature distributions within the
flame flow are measured using thermocouples (Pt/Pt-Rh), which are inserted into
the flame flow through the peepholes (Fig.2) and can be moved across the flame
flow. To obtain the axial and radial distributions of the flame composition and
relative mass fractions of flame compounds, local gaseous samples are extracted
from the flame flow by using microprobe technique and then analyzed by
absorption spectroscopy in the range of 2-15 μm. A portable gas-analyzer (Testo 33R) is used
to study the composition of emissions (CO, ppm; CO2, %; NOx,
ppm), the equivalence ratio of propane air mixture (a) and the
flame temperature at the outlet of the water-cooled channel, as well as at the
outlet of the quartz tube.
The electric field effect on heat transfer to the
water-cooled channel walls is estimated from the calorimetric measurements of
the cooling water flow. The local variations in the ion density are measured
using the double probe technique.
The electric field
effect on soot formation and deposition on the surface of the negatively
biasedl electrode is estimated from measurements of the flame radiation and
weight growth of the deposited coatings.
Effects examined in the flame channel flows include:
· The radial
electric field effect on the processes of mass transfer;
· The
radial electric field effect on the processes of heat transfer;
· The
radial electric field effect on the local flame composition, temperature and rate of fuel combustion;
· The
radial electric field effects on the levels of NOx;
· The
radial electric field effects on soot formation and pre-combustion fuel decarbonization
with electrical control of carbon
capture and sequestration from the flame channel flow;
Parameters varied include:
· Equivalence
ratio of the premixed fuel-air burner exit flow;
· The
fuel-air flow rate;
· The
electric force acting on the flame flow;
· The
electric field direction and configuration in a flame;
· The
density of the ion current to the channel walls.
Subsequent
phases of these researches, which are in development, will include the
numerical simulation of the heat/mass transfer and fuel combustion in the flame
channel flow with account of the electric field effect on the flame channel
flow and levels of the polluting emissions from the flame.
References
1.
Zake M., Purmals
M. The external electric field effect on turbulent propane-butane air flame//
Latvian Journal of Phys. and Tech. Sci.-1993. -Nr.1.-pp. 30-40.
2.
Zake M. The excitation
of gas particles in a flame in external electric field// Latvian Journal of
Phys. and Tech. Sci.-1995. -Nr.1.-pp.10. -18.
3.
Zake M. The
electric field effect on the interrelated heat and mass transfer in a flame//
Latvian Journal of Phys. and Tech. Sci.-1995. -Nr.3.-pp. 14. -23.
4.
Zake M.
Experimental investigation of field and flame interaction// Advances in
Engineering Heat Transfer. -Ed. Bengt Sunden, E. Blums, A.Zukauskas. - CMP. -
1995. -Pp. 461. -469.
5.
Zake M., Lubane
M., Purmals M. Enhanced Electric Field Effect on a Flame //Journal of Enhanced
Heat Transfer, 1998, Vol.5, N3, pp.139-163.
6.
Zake M., Turlajs D., Purmals M. Experimental Investigations of the
Electro-Magnetic Field Effect on the Processes in the Flame //Warmeaustausch und erneuerbare energiequellen, Szczecin- Swinoujscie, Poland, 1998, pp.377-385.
7.
Zake M., Turlajs D., Purmals M. Electric Field Control of
NOx formation in a flame flow// Proceedings of 6-th International
conference on Environmental Science and Technology, 1999, Global NEST, Athens,
Greece, Vol.B, pp 54-61.
8.
Zake M., Turlajs D., Purmals M. Electric field forced heat and
mass transfer in the flame channel flows// Proceedings of 3-rd Baltic Heat
Transfer Conference, Gdansk, Poland, 1999, pp.111-118.
9.
Zake M., Purmals M. Effects
of DC field-enhanced heat and mass transfer on NOx formation in a flame flow //
Proceedings of International Scientific Colloquium "Modelling and Material
Processing, 1999. Riga.
10.
Zake M., Purmals M., The
Electric Field-Controlled Heat and Mass Transfer and Fuel Combustion in the
Flame Channel Flows // Magnetohydrodynamics, 1999, Vol.35, N2, pp.131-142.
11.
Zake M., Turlajs D., Purmals M. Electric Field Control of
NOx formation in the flame channel flows// Global NEST: The
International Journal, 2000, Vol.2, N1, pp.99-109, Athens, Greece.
12.
Zake M., Barmina I., Turlajs D., Electrical Control of
Carbon Capture and Sequestration in the
Flame Flows // Magnetohydrodynamics, Vol.
36, N2, pp. 127-139
13.
Zake M., Barmina I.,
Turlajs D., Electrical Control of Fuel Decarbonization and Processes
of Heat/Mass Transfer in the Flame Channel Flows// Proceedings of Heat Transfer
and Renewable Sources of Energy, Szczecin, Poland, 2000, pp.435-442.
14.
Zake M., Barmina I.
Electrical Control of Flame Carbon and Polluting Emissions from Fuel
Combustion, Modelling for Saving Resources, Int. Sci. Coll., Riga, 2001, pp.
198-204.
LV patents
M.Purmals N5327; N5328; N5331; N5332; N 5333-LV, 1994.