Abstract: Hot exhaust gases from individual cylinders of a diesel engine are cooled and partially cleansed in respective selected heat exchangers. The cooled and partially cleansed exhaust gases discharged from the plurality of heat exchangers are combined and then passed to a single electrostaic precipitation device for further cleansing. When it becomes necessary to regenerate one or more of the heat exchangers, only a single heat exchanger is transferred to a regeneration mode of operation. At this time, all of the other heat exchangers continue to operate in the partial cleansing mode. During the regeneration of the one heat exchanger, the exhaust gases therefrom continue to be mixed with the exhaust gases of the remainder of the heat exchangers. All of the exhaust gases from a given cylinder of the engine always pass through only a single of the heat exchangers.