Analysis On Diesel Exhaust Characteristic Parameters Based On Monitoring Of Diesel Particulate Filter

With the increasingly stringent emissions regulations, Diesel particulate filter (DPF) is now widely used in domestic and foreign diesel engine after-treatment for its high filtration efficiency and low environmental requirements. However, due to long-term or improper application, clogging and breakage failure may occur to the DPF system. Since it is of paramount importance to monitor the system and prevent the aforementioned problems, it is necessary to carry out the research of exhaust characteristics based on monitoring of DPF.The diesel engine model,vehicle model, and DPF models, was established by using GT-Power. Studies were conducted on the characteristics of the exhaust gas temperature of the diesel engine in steady-state and road conditions, and analyses were made on the effects of the operation of DPF on the exhaust temperature. Results show that at steady-state and road conditions, the diesel exhaust temperature is not a suitable characteristic parameter to evaluate the particulate deposition amount of the DPF alone.The variation of the exhaust gas pressure, which is another important parameter of diesel exhaust characteristics, was studied. It is found from the diesel exhaust pressure characteristic in steady-state and road conditions that, the pre-DPF pressure and the DPF pressure drop can be used as a characteristic parameter to evaluate the particulate deposition amount. The influences of particle deposition amount on the exhaust pressure, in terms of average exhaust pressure and exhaust pressure frequency, were studied at steady-state operation. Results show that, the amplitude of the characteristic exhaust pressure frequency can be selected as a reasonable parameter to evaluate the particulate deposition amount over the average exhaust pressure.The influences of particle deposition amount on the exhaust noise were investigated via simulations. It is found that, the amplitude of the exhaust gas pulsation frequency decreases as the particle deposition amount increases. Therefore, the particle deposition amount can be monitored by detecting this amplitude.The effects of DPF damage on the exhaust noise were studied experimentally. Results show that, as the damage deteriorates, the original amplitude of the exhaust pulsation frequency increase, as well as twice this amplitude increases, indicating that the damage of the DPF system can be monitored according to the summation of the two amplitudes. In certain conditions, the peak frequency of the exhaust noise decreases with the extent of the damage. In this case, the damage can be monitored by detecting the variation in the noise frequency.This research provides a basis for future studies on monitoring the clogging or breakage of DPF systems in diesel engines.