Patent ID: 8679852

Claim:
A method of generating exhaust gas that contains a desired amount of particulate matter, comprising: using an engine to generate exhaust gas into a main exhaust flow line that directs the exhaust gas to an emissions control device or a collector; using a particulate matter generator to generate supplemental exhaust gas having desired particulate matter characteristics; wherein the particulate matter generator has at least a burner for receiving fresh air and fuel and combusting the fresh air and fuel to produce exhaust gas and nascent particulate matter in the exhaust gas; a heat exchanger for cooling the exhaust gas downstream of the burner; an oil injector for modifying a soluble organic fraction of the particulate matter; and a quencher for locking the composition of the particulate matter; wherein in the particulate matter generator is positioned on a branch line off the main exhaust flow line, such that the burner does not receive exhaust from the engine wherein the quencher operates by injecting an inert gas into the output of the heat exchanger; operating the particulate matter generator at a rich air-fuel ratio, using a predetermined air-fuel ratio calculated to produce a desired concentration of particulate matter in the exhaust gas; introducing the output of the particulate matter generator from the branch line into the main exhaust flow line; and delivering the combined exhaust from the engine and the exhaust from the particulate matter generator to the emissions control device or collector; wherein the particulate matter generator generates substantially all particulate matter in the exhaust gas, such that the combined exhaust has the substantially the same concentration of particulate matter as is generated by the particulate matter generator; and wherein the concentration of particulate matter in the exhaust gas is of a predetermined amount for testing the emissions control device or collector.