The Suitability Evaluation Of Partial-flow&Dynamic Particulate Sampling System And Selection The Key Parameter

Diesel engine has developed more than100years, and because of its excellentfuel economy and durable reliability, making it as the main source of power ofautomobile and engineering machinery has been widely used. The emissions of dieselengine，s particulate is dozens of times larger than gasoline engine, and become one ofthe major sources of atmospheric environment. So carrying out the research onparticulate measurement system is imminent. International general divided particulatemeasuring system into two kinds one for full-flow dilution sampling system and theother for partial-flow dilution sampling system. Because partial-flow dilutionsampling system is small, inexpensive and then widely used. So on the basis of theexisting hardware structure, this topic decide to develop a set of partial-flow&dynamic particulate dilution sampling system. It not only can measure particulateemissions of steady state conditions, but also have the potential to measure particulateemissions of under transient conditions.First, this paper introduces the principle of partial-flow&dynamic particulatedilution sampling system and calculates the ratio of particulate emissions, then buildspartial-flow&dynamic particulate dilution sampling system. Based on FreescaleMC9S12XSP128MAL microcontroller, this paper builds the control platform ofpartial-flow&dynamic particulate dilution sampling system. I completed the dataacquisition of pressure sensors, temperature sensors, and flow control valve positionfeedback signal, designed control strategy of a flow control valve and the solenoidvalve, and based on PID algorithm designed pressure stability control policy. In orderto monitor the work of the state for the system, this paper completed the preparationof the system PC software based on LABVIEW and simulated communication testbetween PC and electronic control unit, to verify the communication function betweenthe upper and lower place machine.Considering the vibration and temperature of laboratory may have an impact onmeasuring differential pressure sensor, this paper builds the debugging system ofpartial-flow&dynamic particulate dilution sampling system. Simulates the pressure stability under different exhaust gas flow rates and different exhaust back pressure,and it verifies the feasibility of the system. In this paper, tuned the PID parameters,and select the most suitable PID parameters, then used the system measured forparticulate emissions for five times of B50conditions for4D20engine. Then verifiesthe consistency of measurements of the system and calculates the ratio emissionsunder B50conditions. Then used the existing particulate measurement systemmeasured the ratio emissions of B50conditions for the4D20engine, comparing themeasurement results of the two systems, the test results show the applicability of thesystem.Finally this paper wrote common PC software according to LABVIEW, in thiscommon software, the user can enter the engine parameters, we can obtain the keyparameters of the system. Thus for different engine, the users can select the keyparameters of the partial-flow&dynamic particulate dilution sampling system, buildpartial-flow&dynamic particulate dilution sampling system with their requirements,to measure the particulate emission levels of engines.