Abstract
Recent years have already seen tighter regulation on harmful substances such as NOx, CO, and particles. Considering the above situation, it is important to monitor controlling factors of engine systems in order to improve efficiencies of their operations. In car engines an increasing concern in environmental issues such as air pollution, global warming and petroleum depletion has helped drive researches into various ways. Laser diagnostics has been applied to measure species concentration in the actual industrial fields. However there are several challenges to proceed in applying laser diagnostics to practical application. Especially stability of the measurement system is one of the most difficult issues. The purpose of this research is the development of a prompt measurement technique which can be applicable to various engine conditions. The tunable diode laser absorption spectroscopy(TDLAS) using the hollow fiber has been developed to satisfy above requirements. By using a hollow fiber, misalignment of an optical axis and vulnerability of measurement environment such as vibration can be greatly reduced with sensitive and fast response features. It was demonstrated that this method can be applicable to measure gas compositions in engine exhaust with a range of millisecond response time. A sensitive method using tunable UV diode laser absorption spectroscopy was also discussed to detect NOx in exhausts.
