improved the RFR configuration with two DOCs and a noncatalytic DPF. (24) The monolith blocks can enhance heat recuperation, reduce the temperature gradient, and maintain a more stable temperature distribution in the DPF. proposed an RFR structure in which two inert monolith blocks with a flow-through passage are installed at both the ends of a DPF. However, the temperature gradients at the inlet and outlet of the DPF not only defer the regeneration process but also result in additional thermal stress. (22,23) RFR exploits heat recovery properties to provide a high-temperature region that maintains the regeneration of the filter. Reciprocating flow regeneration (RFR) has also been identified to be an effective means to realize active–passive component regeneration of the DPF utilizing a tiny amount of the additional fuel. After a long period of operation, the DPF still needs to be disassembled to clean up the residues in the filter. (17,18) In addition, all forms of regeneration can only remove combustible constituents of the PM trapped in the DPF and cannot remove incombustible constituents remaining behind as ash. This is due to the fact that several factors need to be concerned they are the wide range of engine operations, thermal inertia of the DOC and DPF, the complexities of the reactions in the DOC and DPF, and the injection model of the fuel injectors. Idp dpf off tunes 6.4 how to#As a result, this regeneration method will be facing a challenge on how to control the temperature in the DOC and DPF. The temperature in the DPF should not only be high enough to burn the soot accumulated in the DPF but also be kept below a certain threshold to prevent the DPF from being damaged. Only the temperature in the DOC is kept in the range of 250–450 ☌ NO can be preferentially converted to NO 2. It is known that the active–passive component regeneration of the DOC-assisting DPF should maintain the temperature in the DOC and DPF within a suitable range. It should be noticed that both hydrocarbon (HC) and CO would be the secondary pollutants from incomplete oxidation conversion of the soot in the CRT system. Otherwise, the produced NO 2 will be too low to oxidize soot. (12) In order to achieve the best performance, however, the CRT system should satisfy two conditions: the temperature should be in the range 250–450 ☌ and the NO x/soot ratio should be adequately high. The CRT system is installed with a DOC where NO is preferentially converted to NO 2 before a DPF and NO 2 is used to oxidize PM trapped in the filter below 300 ☌. Diesel oxidant catalyst (DOC)-assisting DPF regeneration is typical of the passive regeneration method which is also named the continuously regenerating trap (CRT) system. (11) On the other hand, passive regeneration utilizes an ongoing catalytic reaction at the exhaust gas temperature to oxidize the PM trapped in a DPF without additional fuel. (10) The external energy used for heating would increase the cost of a DPF system because of complex supplements. (9) In this case, the heat must be supplied from outside sources, such as an electric heater, a microwave heater, and a flame-based burner. Active regeneration periodically removes the PM trapped in a DPF through controlled oxidation with O 2 at 550 ☌ or higher temperatures. There are mainly two types of regenerations of DPF: active regeneration and passive regeneration. Results show that (1) the DPF system can use a tiny amount of extra fuel to maintain the chemical reaction, which in turn realizes the regeneration of the catalyzed DPF because of its properties of heat recovery and reverse blowing of ash (2) with the increase in the reciprocating flow cycle, the temperature profile moves toward the downstream side of the DPF system and the fluctuation amplitudes of the components of CO, NO, and NO 2 increase (3) if reasonable temperature distribution is formed in the DPF system for a certain reciprocating cycle, the regeneration efficiency can be obviously improved and the average content of particulate matter emission can be kept at quite a low level. The mechanism of reciprocating flow regeneration of the DPF system and the effects of the reciprocating flow cycle on the performance of the DPF system are analyzed. Several control parameters such as temperature distribution, pressure difference, and pollution emissions of the DPF system are measured for different reciprocating cycles. In this article, a new diesel particulate filter (DPF) system with reciprocating flow is proposed, and an experimental study on the characteristics of the active–passive component regeneration of the DPF system is carried out.
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