Combustion control and sensors: a review

https://elib.dlr.de/59672/1/scientdir.pdf

Transport impacts on atmosphere and climate: Aviation

Atmospheric aerosols and their effect on clouds are thought to be important for anthropogenic radiative forcing of the climate, yet remain poorly understood. Globally, around half of cloud condensation nuclei originate from nucleation of atmospheric vapours. It is thought that sulfuric acid is essential to initiate most particle formation in the atmosphere, and that ions have a relatively minor role. Some laboratory studies, however, have reported organic particle formation without the intentional addition of sulfuric acid, although contamination could not be excluded. Here we present evidence for the formation of aerosol particles from highly oxidized biogenic vapours in the absence of sulfuric acid in a large chamber under atmospheric conditions. The highly oxygenated molecules (HOMs) are produced by ozonolysis of α-pinene. We find that ions from Galactic cosmic rays increase the nucleation rate by one to two orders of magnitude compared with neutral nucleation. Our experimental findings are supported by quantum chemical calculations of the cluster binding energies of representative HOMs. Ion-induced nucleation of pure organic particles constitutes a potentially widespread source of aerosol particles in terrestrial environments with low sulfuric acid pollution.

/pdf/ion-induced-nucleation-of-pure-biogenic-particles-4qmw6lrim5.pdf

Ion-induced nucleation of pure biogenic particles

Hydroxyl radicals (OH) are a key species in atmospheric photochemistry. In the lower atmosphere, up to ~30% of the primary OH radical production is attributed to the photolysis of nitrous acid (HONO), and field observations suggest a large missing source of HONO. We show that soil nitrite can release HONO and explain the reported strength and diurnal variation of the missing source. Fertilized soils with low pH appear to be particularly strong sources of HONO and OH. Thus, agricultural activities and land-use changes may strongly influence the oxidizing capacity of the atmosphere. Because of the widespread occurrence of nitrite-producing microbes, the release of HONO from soil may also be important in natural environments, including forests and boreal regions.

https://science.sciencemag.org/content/sci/333/6049/1616.full.pdf

Soil Nitrite as a Source of Atmospheric HONO and OH Radicals

https://www.kau.edu.sa/Files/188/Researches/65975_37398.pdf

Aircraft engine exhaust emissions and other airport-related contributions to ambient air pollution: A review

A new in situ instrument (LOPAP:  long path absorption photometer) to measure gaseous nitrous acid (HONO) using wet chemical sampling and photometric detection has been developed. This instrument i...

A new instrument to measure gaseous nitrous acid (HONO) in the atmosphere.

Nonintrusive systems for the measurement on test rigs of aeroengine exhaust emissions required for engine certification (CO, NOx, total unburned hydrocarbon, and smoke), together with CO2 and temperature have been developed. These results have been compared with current certified intrusive measurements on an engine test. A spectroscopic database and data-analysis software has been developed to enable Fourier-transform Infrared measurement of concentrations of molecular species. CO2, CO, and NO data showed agreement with intrusive techniques of approximately ±30%. A narrow-band spectroscopic device was used to measure CO2 (with deviations of less than ±10% from the intrusive measurement), whereas laser-induced incandescence was used to measure particles. Future improvements to allow for the commercial use of the nonintrusive systems have been identified and the methods are applicable to any measurement of combustion emissions.

Nonintrusive optical measurements of aircraft engine exhaust emissions and comparison with standard intrusive techniques.

Fourier transform infrared spectroscopy is an efficient technique for the detection and quantification of molecules in gas mixtures. Measurement results from a mobile laboratory for ambient air analysis and for remote sensing of plume emission with the commercially available K300 spectrometer are reported. CO, CO(2), NO, NO(2), N(2)O, NH(3), CH(4), SO(2), H(2)O, HCl, and HCHO concentrations have been determined with good agreement with in situ results. The on-line multicomponent analysis software is based on line-by-line retrieval and least-squares fitting procedures, including the effects of multiple aerosol scattering and cloud and rain influences.

Mobile Fourier-transform infrared spectroscopy monitoring of air pollution

Because of the worldwide growth in air traffic and its increasing effects on the atmospheric environment, it is necessary to quantify the direct aircraft emissions at all altitudes. In this study Fourier-transform infrared emission spectroscopy as a remote-sensing multi-component-analyzing technique for aircraft exhausts was investigated at ground level with a double pendulum interferometer and a line-by-line computer algorithm that was applied to a multilayer radiative transfer problem. Initial measurements were made to specify the spectral windows for traceable compounds, to test the sensitivity of the system, and to develop calibration and continuum handling procedures. To obtain information about the radial temperature and concentration profiles, we developed an algorithm for the analysis of an axial-symmetric multilayered plume by use of the CO(2) hot band at approximately 2400 cm(-1). Measurements were made with several in-service engines. Effects that were due to engine aging were detected but have to be analyzed systematically in the near future. Validation measurements were carried out with a conventional propane gas burner to compare the results with those obtained with standard measurement equipment. These measurements showed good agreement to within +/-20% for the CO and NO(x) results. The overall accuracy of the system was found to be +/-30%. The detection limits of the system for a typical engine plume (380 degrees C, ? = 50 cm) are below 0.1% for CO(2), ~0.7% for H(2)O, ~20 ppmv (parts per million by volume) for CO, and ~90 ppmv for NO.

Jörg Heland

Papers

A new instrument to measure gaseous nitrous acid (HONO) in the atmosphere.

Nonintrusive optical measurements of aircraft engine exhaust emissions and comparison with standard intrusive techniques.

Mobile Fourier-transform infrared spectroscopy monitoring of air pollution

Analysis of aircraft exhausts with Fourier-transform infrared emission spectroscopy

Determination of major combustion products in aircraft exhausts by FTIR emission spectroscopy