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Research unit
EU RFP
Project number
97.0376
Project title
SAMPLER: Sampling device for the measurement of peroxy radicals in laboratory and field experiments

Texts for this project

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Abstract
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References in databases
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Inserted texts


CategoryText
Key words
(English)
Sampling measurement of peroxy radicals
Alternative project number
(English)
EU project number: ENV4-CT97-0389
Research programs
(English)
EU-programme: 4. Frame Research Programme - 3.1 Environment
Short description
(English)
See abstract
Further information
(English)
Full name of research-institution/enterprise:
EPF Lausanne
Département de Génie Rural
Laboratoire de Pollution Air-Sol / LPAS
Partners and International Organizations
(English)
BUGH Wuppertal, Forschungszentrum Jülich, CEAM Valencia
Abstract
(English)
The task of the EPF Lausanne in the project SAMPLER is to model smog chamber experiments in order to evaluate a new method for measuring RO2 radicals (sampling of RO2 radicals in a cyrosampler and later analysing the samples by ESR spectroscopy).
Because current lumped mechanisms are not sufficiently detailed for this task, the program CHEMATA (CHEmical Mechanism Adaptation to Tropospheric Applications) was designed. CHEMATA can generate extended mechanisms which describe the chemical behaviour of the investigated hydrocarbons and of all resulting products in great detail. The only needed input data are structure reactivity relationships, available experimental values and the chemical structures of VOC compounds. The program transfers the chemical structures into number codes which are used to calculate all rate constants and products of the VOC reactions. Because CHEMATA enables also a lumping of VOC species it will not only be very helpful to laboratory experimentalists but also to 3D modellers who want to create, adapt or update chemical mechanisms for use in 3D models.
Experiments with VOC/HCHO/NOX/air mixtures (VOC = HCHO, ethene, n-butane or iso-butane) were performed in the EUPHORE smogchamber of Valencia, Spain. HCHO which is photolysed by the sun light acts as the radical source in the system. By comparing the simulation results to the measurements we found that in all simulations the calculated ozone values are higher than the measured ones. This is probably caused by an unknown ozone loss process in the chamber, likely by wall reactions. Because of the very low humidity of about 0.01%, ozone is not an important source for radicals; therefore the overestimation of ozone does not affect the simulated peroxy radical mixing ratios.
In the ethene experiment too high simulated HCHO must cause too high calculated HO2 concentrations. In all other experiments calculated and measured HO2 values agree within a range of about 20%. In most of the cases the agreement for the organic peroxy radicals is even better. Only in the case of iso-butane and in the first hour after starting the experiment larger differences between simulation and measurements were found. Considering the uncertainties in the kinetic data on which the calculations are based, an even better agreement could not be expected.

References in databases
(English)
Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. +41 31 322 74 82
Swiss Project-Number: 97.0376