While the motor vehicle industry is focusing on CO2 as the arch evil of emissions, Horiba Europe has revealed a new emissions measurement system for NO, NO2, N2O, and NH3 compounds. Based on QCL (Quantum Cascade Laser) spectroscopy, the company claims that it offers superior performance thanks to its expanded measuring range.
The method can be used for testing gasoline, diesel, and alternative fuel engines, and it's described by the company as being ideal for R&D on exhaust aftertreatment systems.
The QCL operates together with a heated sample handling system that provides fast response to meet Euro VI requirements.
With very significant progress achieved across the auto industry in the treatment of undesirable engine emissions, the ability of instruments to give accurate measurements is increasingly challenging. New techniques are needed and Horiba’s QCL application has been developed to meet those needs.
At this year’s Automotive Testing Expo in Stuttgart, Germany, the company showed its MEXA-1400QL-NX emissions measurement system. Using QCL technology, in diluted measurement, raw gas measurement, and bag measurement tests, results are “extremely precise and reproducible” stated Horiba.
Axel Wendorff, Vice President of Horiba Europe, said that QCL was a major aspect in facilitating reduction of pollutant concentrations together with meeting test requirements for alternative powertrain systems.
It has been developed to significantly improve on FTIR (Fourier Transform Infrared) spectroscopy, achieving added precision at low concentrations as well as offering a wider measurement range. Horiba states that the approximately 20 times finer resolution of the absorption spectrum makes the company’s QL-NX less sensitive to incidental interference from other gases including CO, CO2, CH4, H2O, and hydrocarbons, and it does not suffer from the interference of NOx measurement by NH3 when using the CLA (Chemo Luminescence Analyzer) principle.
Explaining the action of the MEXA-1400QL-NX, the company states that its QCL elements have been developed to produce radiation at precise wavelengths in the mid-IR region. This allows measurement of the various nitrogen compounds that exhibit high sensitivity in that region. The wavelengths of the lasers depend primarily on the design of the QCL and on its controlled temperature. The operation has been developed so there is little need for optimization once the analyzer is adjusted for manufacture, stated Horiba.
It is the use of two optical path lengths within one gas cell that gives the system its very wide dynamic range. The optical cell was also designed to attain fast response times that are comfortably inside Euro VI NH3 measurements.