Heat Transfer Enhancement by Pulse Combustion in Industrial Processes

Heat transfer techniques that can be cost effectively applied to industrial processes have been of continuing interest to industry. Increasing the heat-transfer effectiveness of many processes would lead to greater productivity, efficiency, and in some cases, reduced equipment sizes. One such technique being studied at Battelle is the use of pulse combustion systems in industry. Preliminary results have shown that the heat-transfer coefficient can be augmented by up to 100 percent with this technique, and that heating surface requirements can be reduced by half. Results also show that when coupled with mass-transfer processes, the use of pulse-combustion technology improves the process by up to a factor of 5. The heat-transfer enhancement in pulse combustion systems is due to the oscillation of gas flow within the combustion system. This oscillation follows the periodic combustion process that takes place within the system. The periodic nature of the combustion processes results from the acoustic coupling of the system geometry with the natural tendency of flames to oscillate. The resulting synergism causes the system to operate at resonance with an increase in heat-transfer coefficient ranging from up to four times that of steady, nonpulsating systems. This paper describes the results of heat-transfer measurements and calculations performed at Battelle to determine the degree of beneficial effect of heat-transfer enhancement in pulse combustors in industrial processes. Three types of processes are considered. These are (1) immersion heaters, (2) radiant burners, and (3) direct-fired operations. Measurements are described for heat transfer in a pulse-combustion boiler and in a conventional fire-tube type boiler. In these experiments, heat-transfer coefficient enhancement of 100 percent was measured in the pulse-combustion system. Measurements in a direct-impingement drying experiment are also described. Heat-transfer enhancement of up to 5 times was found in this system