Gaseous Emissions Sampling
The emissions measurement system is designed in accordance with ISO-11,042. Exhaust products are sampled downstream of the quartz confinement in the HPOC using a multi-point equal area probe, connected to a water-conditioned heat exchanger used to regulate the sample temperature to 433 K. A heated pump is used to deliver products to the analysis suite and was also maintained at 433 K together with the filter and sample lines.
NOx (NO + NO2) concentrations are quantified using a heated vacuum chemiluminescence analyser (Signal 4000VM). The sample stream can be redirected through an NH3 to NO converter (Signal 410) to measure unburned concentrations with an 80% conversion efficiency. All NOx and NH3 concentrations are typically measured hot/wet with captured data normalised to equivalent dry conditions.
Additional sample is dried in a chiller before CO, CO2 and O2 concentrations are quantified using a combination of nondispersive infrared and paramagnetic analysers (Signal 9000MGA).
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