ELECTRICAL CONTROL OF COMBUSTION

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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.