Design And Experimental Study Of The Cooling System Of Micron Wood Fiber DPF

With the haze weather appearing frequently around the country, people pay more and more attention to PM (Particulate Matter) widely. The particles from diesel exhaust emission are main sources of PM in atmosphere, there are many pollutants attached to their surfaces, such as metal oxides, carbon hydrogen compounds, sulfate, fine particles and carcinogenic polycyclic aromatic hydrocarbons which could bring serious harm to environment and human health. At present, the diesel particulate filter (DPF) technology is one of the simplest and most effective post-processing techniques applied to control PM from diesel exhaust emissions. The filter core make by micron wood fibers has many advantages, such as high filtration efficiency, low exhaust back pressure, big dusty amount and so on. But natural woods can not stand high temperature exhaust for a long time. Therefore, the cooling of diesel exhaust is the key links of this technology. In this paper, a cooler with tube fins will be developed for cooling exhaust, protecting micron wood fiber filter and extending the service life of DPF.Exhaust temperature is an important basis for the design of cooler. In this paper, firstly analyze the temperature of exhausts around diesel exhaust pipe. Then give full consideration to the effects of silencer and exhaust pipe size on the temperature of exhausts. Secondly, we analyze all process of exhausts from the generation to the discharge, and simplify the model to get a numerical calculation model of gas temperature around the exhaust pipe.Thirdly, according to parameters of diesel engine and size of muffler and exhaust pipe, we design a tube fin type cooler composed by multi-finned tube. This cooler can make the exhaust temperature reduce to 220℃ under the rated condition. Fourthly, we analyze the influence of structural parameters of cooler on the cooling performance by MATLAB. These parameters contain inner diameter, distance between pipes, height of fins, distance between fins.Fifthly, we use the weight function method to optimize the structure of the cooler (cooling area, pressure drop and fin efficiency), then the optimal structure is obtained. Finally, we design a cooling control system based on the C8051, which are used to judge whether the cooler needs to clean by control starts and ends of the cooler according to the temperature and back pressure of exhausts.Build a test bench of tube fin type cooler performance,then use Kingview6.55 software development performance detection system to get efficient data timely and analysis. There are shown that the fin tube cooler has good cooling effect and meets the requirements of micron wood fiber filter, back pressure of exhausts is low at the same times. The cooling control system based on the C8051 can control cooling fan start and stop accurately and quickly according to the minimum and maximum of the temperature exhaust. This device can avoid the use of wind turbines under low temperature conditions and save energy in the car.