Applied Combustion Research at the Gas Research Institute

This paper discusses the effect Frequency Modulation temperature control has on the convective heat transfer coefficient in furnace enclosures of the direct fired type. Rationale is submitted for instituting a control scheme with the inherent ability of improving convective heat transfer in batch type thermal processes. A description of the Frequency Modulation temperature control system is given, including a treatment contrasting this system with the conventional Amplitude Modulation temperature control system. An analysis of the phenomena believed to enhance the convective heat transfer coefficient and unique to Frequency Modulation temperature control is performed. These analyses are based upon models relating the convective coefficient to turbulence induced as a result of the unsteady flow field, burner nozzle exit velocity and burner nozzle momentum flux. Results from experimental testing in a furnace enclosure under simulated operating conditions are analyzed and discussed in relation to the models presented.