Rapid-response measurement system of the halon replacement agent pentafluoroethane (HFC-125) based on QCL-TDLAS

摘要

The measurement of gaseous extinguishing agent's concentration distribution is a main approach to evaluating the performances of aircraft fire protection system. In this paper, we present a novel sensing method-tunable diode laser absorption spectroscopy (TDLAS) for Halon replacement extinguishing agent pentafluoroethane (HFC-125), which has been used in aircraft fire suppression system. A new QCL-TDLAS measurement system for HFC-125 have been developed near the foundation absorption peak at 8.270 urn. Direct absorption spectroscopy (DAS) was used in combination with a novel length-adjustable cell, an inversion algorithm was proposed and used. The performance test of QCL-TDLAS was also conducted in this research: For the 3 mm optical path length, this system can response over a wide range from 100 ppm to 30%, while the prior methods just acquired percentage measurement level; response time 97.2 ms is achieved which is faster than the differential pressure method (140 ms); the results show that the relative error of lOOppm-lOOOppm is less than 0.96% while the relative error of l%-30% is less than 0.34%, the accuracy is higher when compared with the previous methods. To our knowledge, these experiments represent the first application of QCL-TDLAS in HFC-125 measurement. The sensing technique demonstrated here shows promise for real-time gaseous extinguishing agent measurement with better performance.