AbstractUsing numerical simulations shows that particulate trap regeneration does not occur below a certain critical inlet temperature, 679 K, for a typical diesel exhaust mass flow rate of 0.0523 kg/s. A new bypass design for particulate trap regeneration has been studied, where the exhaust flow is divided into several channels, which results in a smaller flow rate in each particulate filter. This reduces the critical inlet temperature by 20 K to 40 K, depending on the number of channels, and allows for improved regeneration efficiency with low electric energy consumption. In addition, a zero‐order analytical estimate for the ignition time is also developed, given by uig = 2.50/ξ + ln|ri| − 0.344, where uig is a dimensionless ignition time, ri is a reduced temperature, and ξ depends upon feed temperature, flow rate, oxygen concentration, and initial deposit thickness. An optimal design using three bypass channels is obtained by theory and simulation. © 2004 American Institute of Chemical Engineers AIChE J, 50: 184–191, 2004