The possibility of a passively regenerated partial CDPF is investigated to reduce PM emitted from in-use agricultural machinery. A typical partial CDPF does not have high filtering efficiency because some open channels exist in the filter; these prevent damage to the filter during a process of filter regeneration. A ceramic monolith-type partial CDPF that has some open channels on the outlet surface is considered in this study. This study compares the PM reduction performance and passive regeneration characteristics of three partial CDPFs and a full CDPF used with an agricultural tractor diesel engine. The results show that the PM reduction efficiency of the partial CDPFs was 67 similar to 81 % when assessed according to ISO 8178-C1 (8 mode). It is also shown that a larger volume of a partial CDPF improves its passive regeneration characteristic. From the experimental results of the balance point temperature (BPT) tests and the exhaust gas temperatures obtained from real operation of diesel tractor, this study confirms that the continuous passive regeneration of a partial CDPF is possible with bigger margin of safety in long-time operation at low temperature conditions compared with a full CDPF.
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