Detection of Greenhouse Gas Precursors from Diesel Engines Using Electrochemical and Photoacoustic Sensors

Abstract

Atmospheric pollution is one of the worst threats to modern society. The consequences derived from different forms of atmospheric pollution vary from the local to the global scale, with deep impacts on climate, environment and human health. Several gaseous pollutants, even when present in trace concentrations, play a fundamental role in important processes that occur in atmosphere. Phenomena such as global warming, photochemical smog formation, acid rain and the depletion of the stratospheric ozone layer are strongly related to the increased concentration of certain gaseous species in the atmosphere. The transport sector significantly produces atmospheric pollution, mainly when diesel oil is used as fuel. Therefore, new methodologies based on selective and sensitive gas detection schemes must be developed in order to detect and monitor pollutant gases from this source. In this work, CO2 Laser Photoacoustic Spectroscopy was used to evaluate ethylene emissions and electrochemical analyzers were used to evaluate the emissions of CO, NOx and SO2 from the exhaust of diesel powered vehicles (rural diesel with 5% of biodiesel, in this paper called only diesel) at different engine rotation speeds. Concentrations in the range 6 to 45 ppmV for ethylene, 109 to 1,231 ppmV for carbon monoxide, 75 to 868 ppmV for nitrogen oxides and 3 to 354 ppmV for sulfur dioxide were obtained. The results indicate that the detection techniques used were sufficiently selective and sensitive to detect the gaseous species mentioned above in the ppmV range.

Detection of gaseous pollutants emitted from engine powered by biodiesel and diesel mixtures

“…In Figure 2, CO concentration was the lowest in the low speed rotation mode, except for the binary mixture B50. This result was consistent with the work of Mothé (2010) [43] and Ileri and Koçar (2009) [44], who reported that during the operating cycle, the catalytic activity is higher due to increased exhaust temperature, reducing CO emissions. Almeida (2002) [45] explains that as a greater amount of air provided to increase the rotational speed of the engine, the intensity of turbulence in the combustion chamber is increased, affecting the process air-fuel mixture, resulting in increased rate of complete combustion, thereby reducing CO emissions.…”

“…No significant change with the addition of higher biodiesel concentrations could be observed, except for B50, in which the emitted gas was reduced. As the carbon dioxide gas comes from the complete combustion which was related to the temperature of the gases, when using the engine at high rotation, the temperature was increased, providing the best gas emission that has been observed in the results [43]. Figure 2 shows the obtained carbon monoxide (CO) concentration after combustion in a diesel engine operating on different binary mixtures of soybean biodiesel and diesel oil.…”

Ethylene detection in fruit supply chains

“…This indicates that a measurement system for mobile use is available. Other examples for research on this topic are described in Lima et al [20], Mothe et al [21], Schmitt et al [22] and Nägele et al [23].…”

Evaluation of Gaseous Emission in the Use of Biofuels in Brazil

“…The methods for determining gases concentration were previously described in methodology. CO 2 concentration was determined by Infrared Analyzer (URAS), N 2 O concentration was determined by a photoacoustic spectrometer, similar to that described in Figure 1, but using a semiconductor quantum cascade laser (QCL) [20,[60][61][62][63][64][65][66][67][68][69][70] with an emission band ranging from 7.71 μm to 7.88 μm as the excitation source and a resonant differential photoacoustic (PA) cell as detector. The laser was fed applying pulsed current (26.2 mA) with a repetition rate of 400 kHz and a pulse duration of 50ns (duty cycle of 2%).…”