Design and optimization of exhaust gas aftertreatment system for a heavy-duty diesel engine

Diesel engines meeting the latest emission regulations must be equipped with exhaust gas aftertreatment system,including diesel oxidation catalysts(DOC),diesel particulate filters(DPF),and selective catalytic reduction(SCR).However,before the final integration of the aftertreatment system(DOC+DPF+SCR)and the diesel engine,a reasonable structural optimization of the catalytic converters and a large number of bench calibration tests must be completed,involving large costs and long development cycles.The design and optimization of the exhaust gas aftertreatment system for a heavy-duty diesel engine was proposed in this paper.Firstly,one-dimensional(1D)and threedimensional(3D)computational models of the exhaust gas aftertreatment system accounting for the structural parameters of the catalytic converters were established.Then based on the calibrated models,the effects of the converter’s structural parameters on their main performance indicators,including the conversion of various exhaust pollutants and the temperatures and pressure drops of the converters,were studied.Finally,the optimal design scheme was obtained.The temperature distribution of the solid substrates and pressure distributions of the catalytic converters were studied based on the 3D model.The method proposed in this paper has guiding significance for the optimization of diesel engine aftertreatment systems.

New-type Agent for Fabrics Aftertreatment

A new type of TS series agent for the treatment of fabrics is being made by the Beijing Junsheng Fine Chemical Industry Co., Ltd. with the assistance of the Chemistry Research Institute of the Chinese Academy of Sciences. The product is a highly-effective treatment containing organic silicon

Numerical and Experimental Study of a Tornado Mixer

A new design of a selective catalytic reduction(SCR)mixer called tornado was developed for a heavy-duty diesel engine to solve the urea deposition problem.A combination of CFD simulation and experimental studies was used to comprehensively evaluate the performance of the tornado mixer.According to the numerical simulations,this mixer can improve the front surface flow uniformity of the SCR carrier by 6.67%and the NH3 distribution uniformity by 3.19%compared to a traditional mixer.Similarly,steady state SCR conversion efficiency test results have shown that the tornado mixer can increase the average SCR conversion efficiency by 1.73%compared to a traditional mixer.Therefore,the tornado mixer outperforms traditional mixers in terms of mixing uniformity,resistance to deposition and impact on NOX emissions.In addition,a dimensionless parameter,the“limiting deviation rate”,is proposed in the present study to improve the mixing uniformity assessment method for SCR mixers(with the explicit intent to evaluate the mixing uniformity more accurately).

Advances in emission control of diesel vehicles in China

Diesel vehicles have caused serious environmental problems in China.Hence,the Chinese government has launched serious actions against air pollution and imposed more stringent regulations on diesel vehicle emissions in the latest China VI standard.To fulfill this stringent legislation,two major technical routes,including the exhaust gas recirculation(EGR)and high-efficiency selective catalytic reduction(SCR)routes,have been developed for diesel engines.Moreover,complicated aftertreatment technologies have also been developed,including use of a diesel oxidation catalyst(DOC)for controlling carbon monoxide(CO)and hydrocarbon(HC)emissions,diesel particulate filter(DPF)for particle mass(PM)emission control,SCR for the control of NOx emission,and an ammonia slip catalyst(ASC)for the control of unreacted NH3.Due to the stringent requirements of the China VI standard,the aftertreatment system needs to be more deeply integrated with the engine system.In the future,aftertreatment technologies will need further upgrades to fulfill the requirements of the near-zero emission target for diesel vehicles.