Cr – series FTIR Gas Analysers Engine Emissions Monitoring System

1. Cr – series FTIR Gas AnalysersEngine Emissions Monitoring System Antti Heikkilä GASMET Technologies

2. CR-series FTIR Gas Analysers OVERVIEW

3. Cr-series Four models • CR1000 • 1cm, 4 cm, 10 cm path length, peltier cooled detector • CR2000 • 40 cm or 200 cm path length, LN2 detector • CR2000 s • 40 cm or 200 cm path length, LN2 detector • 14 Hz scan rate, RS-422 COM port (921.6 kb/s) • CR4000 • 980 cm path length, LN2 detector

4. Cr-series Typical applications • CR1000 • Catalyst research, process optimization studies • CR2000 and CR2000 s • Engine emissions monitoring, other R&D applications calling for rapid instrument response and short measurement time (500 to 1000 ms cycle) • CR4000 • Trace gas analysis in laboratory applications or e.g. Gas manufacturers’ quality assurance monitoring

5. Cr series vs Cx and Dx series • Cr-series enclosure • Larger enclosure, more space for different detector and sample cell arrangements, including some not available in other series • Will be replaced by Cx-style 19” enclosure in the future (all detectors and cells) • CR2000 s is already built in a 19” rack mounted unit • LN2 detectors • Wide spectral range (4200 ... 700 cm-1, potentially 7000 ... 700) • Better SNR at all wavelengths, especially in the low wavenumber end • Good SNR means that same detection limits are achievable with less scans / shorter measurement • ZnSe optics • Antireflection coated Zinc Selenide windows are transparent down to 650 cm-1 and have better transmission than BaF2 windows • Some gases are reactive towards ZnSe (CR1000 !) and BaF2 or Silicon windows may be used if sample matrix requires it

6. CR100m • The 100 meter instrument has been discontinued • There are parts available for building one if necessary • While the 100 meter cell has very low detection limits, it suffers from long response time • Large internal surface of anodized aluminum (≈ 1 m2) and a large gas volume (30 liter) require long flush times up to 45 minutes • Due to long optical path length, absorption of atmospheric levels of H2O are significant (comparable to 30% in CX4000 / DX 4000) • It has been difficult to find an application where the drawbacks could be accepted • Applications calling for detection limits < 100 ppb are often not good FTIR applications (other technologies with high sensitivity exist)

7. Engine emission system • CR2000 s analyser • Gasmet computer with RS422 COM port • Special sampling system incorporating a high flow rate pump (KNF N0100ST.16E) • Fine particle filter in probe, no particle filter in pump unit • Heated lines 5 m + 1 m • Nominal flow rate 100 lpm

8. Engine emission system • 600 mm × 600 mm footprint • Same cabinet as CEMS II, only shorter • Wheels available • Old sampling system shown • New sampling system will be masked behind a front plate • Liquid nitrogen filled from top of cabinet

9. Engine emission system • NO injected at probe (105.0 s) • NO concentration reaches 10% of target at 105.92 s • NO concetration reaches 90% of target at 106.60 s • Lead time = 0.92 s • Rise time (t10-90) = 0.68 s • Overall response time is 1.60 s Response time test with NO NO injected t10-90

10. Comparison with Horiba MEXA • Comparison of Gasmet CR2000s and Horiba Mexa (Chemiuminescence) NOx analysers • Overall timing of peaks and average concentration level between peaks is in fair agreement

11. Comparison with Horiba MEXA • FTIR records higher and somewhat narrower peaks – better response time than the Horiba CLD analyser which is the industry standard for NOx measurement at the moment. Here is a close-up of a short period where the peak width is well visible:

12. Calcmet v11 Pro and Engine emission monitoring system • Calcmet Pro is required for fast measurement mode (921 kb/s data transfer over RS-422 cable) • Calcmet Pro supports AK protocol for full integration with engine and chassis dynamometer instrumentation • AK protocol is a Modbus-like serial bus protocol, where a master sends commands (ASCII strings) to slave devices • Commands include measurement result query, sampling system control, start/stop measurement and forced measurement of zero calibration and zero / span checks

13. Fast Measurement Mode • Number of scans can be chosen freely (2 – 14, even number) • Measurement interval is the time between starts of consequtive measurements • Interval consists of: • Scanning interferogram • Computing spectrum • Transferring data • Analysis • Writing to disk and outputs • Waiting for interval to roll over

14. AK protocol in Calcmet • Choose AK option in Configration > Serial Output menu • Enable remote control • Define output channels in Edit > Analysis Settings > AK protocol menu • Up to 32 channels can be defined

15. Typical AK request and reply Command contains a function code (STBY = go to standby mode) and device ID. Device with corresponding ID echoes function code and adds an error status to message

16. AK commands in Calcmet

17. AK error codes in Calcmet C denotes custom code, not available in standard configuration of engine emission monitoring system. These were originally created for MAN Diesel.

18. CR2000 in on-road emission monitoring

19. CR2000 and PSS • Portable sampling system used as space was critical • Other instruments for ambient air monitoring and particular matter analysis • Combined data from tailpipe and ambient air compared against location and traffic density