Combustion Control based on Flame Ionization and its Application in Condensing Heating Appliances

Small-scale gas-fired applications such as condensing heating appliances require robust and cost-effective combustion monitoring and control concepts for the clean and reliable combustion of natural gas which is subject to fluctuating compositions. This work presents fundamental investigations on the ionization process in free flames by means of numerical simulations which are complemented by experimental studies on the ionization current detection on burner stabilized flat flames. The technical applicability of a closed-loop combustion control system which is based on the flame ionization current detection is furthermore studied and demonstrated on a condensing heating appliance.