Compact porous medium burner and heat exchanger for household applications
The result of the project was a marketable device for the delivery of heat and/or hot water achieved by advanced development work on a novel porous medium burner with integrated heat exchanger. This burner does not work as a catalytic combustor, but burns within the pores of an inert porous medium. The combustion inside the porous medium is very intense and the reaction zone in the porous matrix has an elongated form in the streamwise direction when using premixed natural gas with air under atmospheric pressure. The matrix properties are employed to stabilize the combustion process in such a way that a power modulation of 1 to 20 results for excess air ratio values of between 1.1 and 1.7. The emission rates are comparable to the best gas burners currently available on the market. The heat exchanger is embedded in the porous medium, so that, due to the high heat transport rates, a highly efficient, compact and integrated burner/heat exchanger apparatus results. Due to its small size compared to conventional fossil fuel heaters, new applications in the household and industry can be foreseen. By optimizing not only the burner itself, but the whole peripheral unit, a highly developed, highly integrated device could be achieved. The complete device is fully equipped with necessary control units that are essential for a safe and flawless operation over a longer period of time. The control unit was developed not only with respect to its functionality, which had to be adapted to the operational characteristics of the porous medium burner, but also with respect to a compact design, so that it can be used as a basis for the commercial utilization. As a result, various burner prototypes for different thermal heat loads were obtained, which are completely novel and provide significant advantages compared to current heating systems. Several manufacturers of heating systems in Europe have already expressed interest in producing the porous burner unit with integrated heat exchangers, and a following THERMIE project should guarantee a proper demonstration action of these novel devices leading to a market introduction late in 1999.