Combustion Control Based on Flame Ionization Bosch Thermotechnology

Combustion Control Based on Flame Ionization Bosch Thermotechnology è è è 100% subsidiary of Robert Bosch Gmb. H Sales Volume 2012: 3. 1 bn EUR, 13 700 associates Product portfolio: o Wall-hung boilers o Floor-standing boilers o Heat pumps o µCHP o Ventilation/ AC o Large-scale systems Local and international brands. 1 TT-WB/EAP 2 -We | 2/27/2014 | © Robert Bosch Gmb. H 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Combustion Control Based on Flame Ionization Condensing Heating Appliances è Most commonly installed technology in many European markets (e. g. UK, DE, NL) 4. 5. è è è 2 Premixed combustion of natural gas and condensation of flue gas for highest efficiency and minimal emissions Conventional systems relying on pneumatic correlation between fuel and air flow for mixture preparation Requires design and installation according to locally supplied gas quality Active Combustion Control 3. 2. 1. 1. 2. 3. 4. 5. Air intake Gas valve Air fan Burner Heat exchanger 6. Flue pipe TT-WB/EAP 2 -We | 2/27/2014 | © Robert Bosch Gmb. H 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights. 6.

Combustion Control Based on Flame Ionization Active Combustion Control 3 è Decoupling of air and fuel supply by means of an electronic gas valve è Continuous monitoring of combustion quality (equivalence ratio estimation) è Active control of fuel and air supply to maintain optimal equivalence ratio, independent of fuel composition TT-WB/EAP 2 -We | 2/27/2014 | © Robert Bosch Gmb. H 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Combustion Control Based on Flame Ionization Current Detection è Application of bias potential U across the flame allows the detection of an ionization current Iion due to the present charge carriers è Combustion control is based on characteristics of the ionization current, most importantly its sensitivity w. r. t. the equivalence 1 -d simulations ratio on ionization in flames Iion 4 TT-WB/EAP 2 -We | 2/27/2014 | © Robert Bosch Gmb. H 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Combustion Control Based on Flame Ionization Research on Ionization Processes in Flames è è Ions and electrons are created through intermediate chemical reactions in the course of combustion Numerical simulations on charge carrier generation in free flames air/ fuel mixtur e burnt gases reaction zone adiabatic flat flame model 5 Positive (left) and negative (right) charge carriers in an atmospheric, stoichiometric methane-air flame. TT-WB/EAP 2 -We | 2/27/2014 | © Robert Bosch Gmb. H 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Combustion Control Based on Flame Ionization Numerical Simulations on Charge Carrier Generation è Charge carrier generation is sensitive to variations in the equivalence ratio, showing very similar characteristics for fuel compositions Methane-air flame: Cumulative peak charge carrier concentrations. 6 different Electron peak mole fractions for different fuel types. TT-WB/EAP 2 -We | 2/27/2014 | © Robert Bosch Gmb. H 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Combustion Control Based on Flame Ionization Current Detection on Flat Flames è Experimental studies on burner stabilized one-dimensional flames and flat electrode setup (gauze electrode) A electrode distance DC voltag e Schematic and experimental setup with the Flat Flame burner from Holthuis & Associates. 7 TT-WB/EAP 2 -We | 2/27/2014 | © Robert Bosch Gmb. H 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Combustion Control Based on Flame Ionization Current Detection on Flat Flames è Current-voltage relationship is dependent on the flame properties and electrode alignment è Transition to a constant, equivalence ratio dependent saturation current for elevated bias potentials è Saturation current as a measure for the overall charge carrier generation in the flame (see flame simulations) Methane-air flame: Currentvoltage relationship for a constant fuel flow rate and different equivalence ratios. 8 TT-WB/EAP 2 -We | 2/27/2014 | © Robert Bosch Gmb. H 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Combustion Control Based on Flame Ionization Saturation Current: Impact of Fuel Composition è Comparison of saturation current w. r. t. equivalence ratio for different fuel compositions Methane-nitrogen fuels. 9 Methane with hydrogen admixtures. TT-WB/EAP 2 -We | 2/27/2014 | © Robert Bosch Gmb. H 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.

Combustion Control Based on Flame Ionization Summary & Conclusions 10 è Active combustion control allows the continuous adaptation to changing fuel compositions in order to maintain optimal combustion è Ionization current detection provides fast, cost-effective and reliable derivation of equivalence ratio for various fuel compositions è Detection setup and control algorithms must guarantee precise and robust operation of installed appliances under all possible conditions TT-WB/EAP 2 -We | 2/27/2014 | © Robert Bosch Gmb. H 2014. All rights reserved, also regarding any disposal, exploitation, reproduction, editing, distribution, as well as in the event of applications for industrial property rights.