The Research On Testing Technology For The Diesel Engine Emission Based On The Tunable Laser Absorption Spectroscopy Technology The Research On Testing Technology For The Diesel Engine Emission Based On The Tunable Laser Absorption Spectroscopy Technology

Marine diesel engine emission has become an important pollution source of the atmospheric pollution,so the emission regulations become more and more strict.The emissions regulations make high requests to the emissions test method.In the future,the emissions test method must develop to high precision,portable,multi-component synchronous on-line measurement.The traditional emission test methods are sampling method,which have a long response cycle.The system structure an operation are complex.It is difficult to calibration,which may bring additional chemical reaction.So the traditional methods can not realize the real time on-line measurement for the emissions of the marine diesel engines.So,the research on the on-line testing technology for marine diesel engine emissions is imminent.At the same time,the on-line measurement for the combustion product and the emissions is benefit to the research on the performance of marine diesel engines,to optimize the combustion process and the controlling strategy.This paper aims to breach bottleneck problem of the emissions on-line measurement for the marine diesel engines by the TLAS,which can solve the existing problems and shortcomings of existing testing technology.First,the on-line measurement method for the marine diesel engines based on the tunable laser absorption spectroscopy technology(TLAS)is researched.The formation mechanism of molecular absorption spectrum is studied in details.The coupling parameter problem of molecular absorption spectrum is analyzed.The absorption lines of the target molecular are selected according the characteristics of the engine emissions,which can avoid the disturb from other molecular.The mechanism of TLAS based on the Lambert-Beer absorption law is studied in details.The feasibility of the concentration,temperature and the pressure measurements for marine diesel engines by TLAS are analyzed.The effects from the fluctuation of environmental temperature and pressure to the spectral parameters are studied.The correction algorithms are given in this work.The scattering model is established to research the effects from the PM scatter,then the scattering correction algorithm is also given.Second,the measurement system for the static mixture gas concentration is designed,which can mix the combination gas.The NO and CO gas are chosen to be the target gas.The experiment of the static gas concentration measurement is studied.The direct detection and the harmonic detection are adopted.The experimental data is match the true value very well.The tunable solid-state laser is used for the gas concentration measurement also.An tunable Tm:YLF laser is designed to realize the concentration measurement of the CO mixture gas,which can realize a higher concentration resolution.The optical loss error bring by the PM is analyzed,where the carbon nanoparticles is used to simulate the PM in the emission.The correction algorithms of the PM to the system is studied.The signal processing method based on the normalized 2f signal by the 1f signal is studied,which can avoid the errors to the experimental data bring by the PM optical loss in the emissions.At last,the on-line measurement system based on TLAS is designed.The NOx CO and CO2 emission on-line measurement is studied on the TBD620 Single-cylinder engine and the D4114B diesel engine.The direct detection and harmonic detection are used to realize the on-line measurement,under the different working points of the diesel engines.A concentration resolution of ppbv is realized by the TLAS system,which has a time resolution of ms.In this paper,the extinction theory is combined with the TLAS,which can realize the measurement of the emission concentration and the smoke-intensity at the same time with out increasing the system hardware.The method increases the practical value of TLAS system to the measurement of the marine diesel engines.The feasibility of the emissions on-line measurement for marine diesel engines is demonstrated by the research in this paper.The high precision measurement is realized with the correction algorithm for environmental parameter(temperature,pressure and the PM concentration).The transient emission and the smoke-intensity information is obtained by the TLAS system,which is significant to optimize the combustion process and the controlling strategy.