Preliminary Evaluation of a Porous Metal Diesel Particulate Filter

Because diesel engines operate on an efficient thermodynamic cycle at a low economic cost, their particulate pollution has been tolerated. However, the Environmental Protection Agency is now setting more stringent particulate emission standards to be met by all diesel-powered vehicles. One candidate system to meet the new EPA requirements is a continuously regenerative porous metal trap oxidizer device. A test program was initiated to evaluate the design and performance of this diesel particulate filter (DPF) on a single-cylinder diesel engine. This DPF is comprised of a rotating porous metal filter element driven by a variable speed electric motor, a heater element for filter regeneration, a nozzle for controlling the particulate deposit pattern on the filter element, a scraping device to insure proper filter regeneration, and a stainless steel housing. A 20-micrometer powder metal element and a 21-micrometer fiber metal element were tested. Collection efficiences in the 70 to 80 percent range were obtained for the optimum combination of heating and scraping for the 20-micrometer powder metal element at a pressure drop across the DPF of under 13 inches of water.