TRACE-GAS Blog

Kick-Down-NOx method for PTI NOx measurement by KNESTEL

With the “Kick-down NOx” measuring device, we have developed another innovation in the field of exhaust gas measurement that could revolutionize the measurement procedure of NOx in the PTI environment.
A kick-down is understood to be the rapid, complete depression of the accelerator pedal starting from idle up to the speed limit. With our “Kick-down NOx” measuring device, the NOx emission of vehicles can be determined quickly and independent of location. All that is required is a warmed-up vehicle, attaching the probe to the exhaust and performing three kick-downs at idle.
By determining the peak values of the NO concentration and averaging these three values, a reliable statement can be made about the NO concentration, which is at the same level as in the classic, continuous measurement, e.g. on the test bench.

The compact “kick-down NOx” measuring device contains our CLDmini NO sensor as well as further components for sample gas preparation, control and data evaluation. It is distributed under our umbrella brand KNESTEL but uses TRACE-GAS components and know-how. From the pump to the ozone destroyer and a display for operation, everything is integrated to perform a location-independent and fast measurement. This results in a complete package for this innovative NOx measurement method, which is available in an attractive cost range.

Chemiluminescence detectors for NOx measurement

The underlying chemiluminescence effect is based on the reaction of nitric oxide (NO) with ozone (O₃). The reaction of nitric oxide with ozone produces oxygen and excited nitrogen dioxide molecules (NO₂*). During the transition of the molecule to the energetic ground state, light of a certain energy/wavelength is emitted.
The concentration of nitric oxide molecules is proportional to the emitted radiation. The reaction occurs very rapidly and can be realized with very small sample volume, which allows analysis with response times in the range of milliseconds. Nitrogen oxides are produced in particular during combustion, which is why this analysis method is used in exhaust gas analysis of power plants, in the automotive industry and in environmental technology.

You can also find more info about the technology here: https://www.trace-gas.com/technology-las-pas-cld-ndir/chemiluminescence/

Advantages for PTI measurement processes

The high-speed measuring device offers many advantages for the use in PTI:

✅ High sampling rate (100 Hz) and fast response time (milliseconds).
✅ Exact reproduction of the NO concentration peak despite short measurement duration
✅ Direct measurement by CLD method
✅ Mobile and locally independent use due to portable case in battery operation
✅ Possibility to combine with other sensors (e.g. particle counter)
✅ Probe for sampling the measuring gas directly at the tailpipe
✅ Evaluation of the measured data via data logger on the laptop
✅ No consumables

Find more info and an interesting white paper on the topic here: https://knestel.de/en/solutions/automotive/kick-down-nox-measurement/

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