Efthimios Zervas

Emission of specific pollutants from a compression ignition engine. Influence of fuel hydrotreatment and fuel/air equivalence ratio

A compression ignition engine is used for the study of the fuel (one reference and one hydrotreated) and the fuel/air equivalence ratio influence on the exhaust emissions of specific pollutants. Under the experimental conditions used, seven hydrocarbons, nine aldehydes and three organic acids are detected in the exhaust gas. No alcohols are detected under these conditions, indicating that these compounds are emitted only if they (or probably other oxygenated compounds) are introduced in the fuel. Fuel hydrotreatment decreases most of the exhaust pollutants, the four toxics and also the quantity of the ozone that could be formed from the exhaust gas. It also changes the composition of exhaust gas: it increases the proportion of methane, benzene, formaldehyde, acetaldehyde, acroleine, and propionic acid, while it decreases the proportion of all other pollutants detected. Fuel/air equivalence ratio also decreases most of the exhaust emissions, the emission of the total toxics and the quantity of the ozone that could be formed. It also changes the proportion of each pollutant in exhaust gas: the percentages of methane, benzene, acetone and acetic acid increase, while those of the other pollutants detected decrease. The majority of the specific pollutants detected corresponds to organic acids, followed by hydrocarbons and aldehydes.

Organic acids emissions from natural-gas-fed engines

A natural-gas-fed spark-ignition engine, operating under lean conditions, is used for the study of the organic acids exhaust emissions. These pollutants are collected by passing a sample of exhaust gas into deionised water. The final solution is directly analysed by HPLC/UV at 204 nm. Only formic acid is emitted in detectable concentration under the experimental conditions used. Its concentration decreases with the three engine operating parameters studied: spark advance, volumetric efficiency and fuel/air equivalence ratio. Exhaust formic acid concentration is also linked with exhaust oxygen concentration and exhaust temperature. A comparison with other engines (SI engines fed with gasoline and compression ignition engines) from bibliographic data proves that natural-gas-fed engines emit less organic acids than the other two types of engines.

Collection and analysis of organic acids in exhaust gas. Comparison of different methods

Abstract This paper reports the development of a specific method to identify organic acids in exhaust gases. The organic acids are collected in two impingers containing liquids (pure water or Na 2 CO 3 1% aqueous solution) and four cartridges containing solids (silica, fluorisil, alumina B and alumina N). Once collected, the acids are eluted of the solids by a hot water stream. These traps performances, in terms of organic acids collection and elution efficiency, are evaluated and compared. Two sources are used to produce the gas flow containing organic acids: one generates a flow whose concentration is known and stable, the other produces organic acids among other combustion products. For eluted solutions analysis, two methods are used: isocratic ionic chromatography/conductivity detection and GC/FID. Their efficiency in separating 10 aliphatic acids are compared. Their characteristics such as detection limits, detection linearity, repeatability and possible interferences with other components found in exhaust gases are determined. The stability of the organic acids solutions is also studied. Lastly, the use of these methods is illustrated by the analysis of the gas-phase organic acids exhausted by a spark ignition and by a diesel engine.

Physical characterization of the aerosol of an electronic cigarette: impact of refill liquids.

Abstract Electronic cigarettes are used to evaporate a mixture of solvents, nicotine and flavors. Liquid particles can be generated under these conditions due to evaporation/condensation. The objective of this work is to measure the physical characteristics of the aerosol emission of an e-cigarette using different refill liquids. The aerosol particle number and size are determined with a Scanning Mobility Particle Sizer. Seven liquids are used: propylene glycol (PG), glycerol (VG), a mixture 1:1 of PG/VG, the mixture with 2% or 5% of a commercial flavor, the mixture with 1.2% of nicotine and the mixture with 1.2% of nicotine and 2% of flavor. Particle concentrations of the aerosol emitted from the electronic cigarette are 300–3000 times higher than that of the ambient air. Propylene glycol emits several times more than glycerol. The addition of a flavor or nicotine has little effect on the emission of the total number emitted. The count median diameter of the electronic cigarette particles is 200–400 nm, depending on the liquid used. Count median diameter of emitted particles is affected by the liquid used.

Presence of music while eating: Effects on energy intake, eating rate and appetite sensations

The role of music in energy and dietary intake of humans is poorly understood. The purpose of the present laboratory study was to examine the effect of background music, its presence and its intensity, on energy intake, eating rate and appetite feelings. The study had a randomized crossover design. Twenty-six normal weight and overweight/obese men participated in random order in three trials: the control trial (no music was playing), the 60dB and the 90dB music trials, while an ad libitum lunch was consumed. Visual analogue scales for hunger, fullness/satiety, as well as desire to eat were administered to the participants. Energy intake at the ad libitum lunch did not differ between trials, even when covariates were taken into account. There were no statistically significant differences between trials on meal characteristics, such as meal duration, number of servings, number of bites eaten and on appetite indices. Future studies are needed to replicate these results and investigate the effect of different types of music and/or sound.

Analysis of acceptance of the smoking ban in Greece.

Background Exposure to secondhand smoke, according to the World Health Organization is responsible for 603,000 deaths in 2004. The ban on smoking in public places in Greece was legislated but not implemented, as the adequate and effective measures were not taken. This study aims to determine the degree of acceptance of the last anti-smoking law and the parameters associated with the acceptance or not of the smoking ban.