•This experiment was conducted at various high altitudes.•The emissions of CO, THC and PM decreased when using biodiesel at each altitude.•Reduction of THC and PM emission caused by biodiesel decreased at higher altitude.•Slight decrease of NOX emission of biodiesel were observed at each altitude.As a widely recommended alternative fuel for diesel engines, biodiesel has been proven to be useful for the reduction of emissions from diesel engines, especially particle emissions. Equipped with an on-board engine test bench and a portable emission measurement system designed for mobile tests, this work investigated the emission of a Euro III emission standard heavy-duty diesel engine fueled with petroleum diesel and soybean-oil biodiesel at four different altitudes. Combustion data were also collected during the emission test at each altitude, which was helpful for the analysis of the emission results. These results showed that the use of biodiesel at high altitude advanced the start of ignition and reduced the proportion of the premixed combustion stage. The PM (particulate matter), THC (total hydrocarbon) and CO (carbon monoxide) emissions of the engine fueled with biodiesel were reduced at each investigated altitude, but the reduction of PM and THC emissions caused by biodiesel decreased as the altitude increased. The NOX (nitrogen oxides) emission of both fuels showed no obvious variation with altitude, and the use of biodiesel led to a slight reduction in NOX emission.

•Dilution air refine system’s advantage in purifying dilution air was confirmed.•Both exhaust and evaporative emissions of a passenger car were investigated.•Unregulated pollutants of evaporations from a car fueled with gasoline and M15.•Evaporative emission characteristics from gasoline/M15 fueling car were studied.Exhaust and evaporative emissions including regulated and unregulated pollutants emitted from a passenger car fueled with gasoline and M15 fuel (M15 means the fuel was consisted with 85%gasoline and 15% methanol by volume) were discussed in this paper. To improve the measurement accuracy of the unregulated pollutants, the dilution air refine system (DAR) was introduced. The exhaust emission tests were performed on the chassis dynamometer, emission factors were measured by a constant volume sampling (CVS) system equipped with DAR over the New European Driving Cycle (NEDC). The evaporative emission tests were performed in the Sealed Housing for Evaporative Determination (SHED). Carbonyls, volatile organic compounds (VOCs) and methanol were sampled through the battery-operated air pumps using tubes coated with 2,4-dintrophenylhydrazine (DNPH), Tenax TA and silica gel respectively. The test results show that comparing with gasoline operations, THC and CO from passenger car fueled with M15 decreased by 16% and 7% while the NOX increased by 85%. The formaldehyde emitted from M15 fueling passenger car was almost two times larger than that from gasoline fueling. For the evaporative emissions, diurnal losses are far more than hot losses and turn out to be the main contributor to the evaporative emissions. For different fuels, evaporative THC from M15 increased by 63%. Given the unregulated pollutants, carbonyls and VOCs increased by 19% and 23%. Moreover, methanol from M15-fueling car was 128 times higher than that from gasoline fueling. It is important to research new canister to decrease the evaporative emissions.

The effects of fuel sulfur content and diesel oxidation catalyst on number-size distribution, sulfate, and trace metals of particulate matter (PM) emitted from a Euro 3 light-duty diesel engine have been investigated. Three types of diesel fuel with sulfur content of 1000 ppm, 350 ppm and 19 ppm respectively were used in this study. According to the results, the number concentration of nanoparticles for low sulfur fuel compared to other two fuels decreased, but accumulation and coarse mode particles increased. With the use of DOC, the number concentration of different size range reduced at 50% load; while at full load, the reduction efficiency was 20−80% for 19 ppm sulfur fuel, and 30−50% only for nanoparticles for other two fuels. The results revealed that the presence of the catalyst and variations in fuel sulfur content altered the extent to which hydrocarbons and sulfates condense on the soot particles and the exhaust sampling methodology promoted the additional coagulation. Both sulfate emission rate and fuel consumption increased with sulfur content. Higher fuel consumption at higher load increased the concentration of SO2, and thus resulted in the generation of large concentration of sulfate. At low load, sulfate to PM mass ratio with DOC was less than that of without DOC; whereas at medium and high loads, the results were contrary. At medium and high loads, catalyst temperature was higher, which converted SO2 into SO3 effectively, and thus generated sulfate. The emission rates of Na, Ca, Mg, K, Al, Ni, and Cr for higher sulfur fuel were more than those for lower sulfur fuel. After engine was retrofitted with DOC, Na, K, and Fe emission increased regardless of load. The emission of Mg, Zn, Cu, and Ca were affected by DOC, as well as by load level.

With mutagenic and carcinogenic potential, polycyclic aromatic hydrocarbons (PAHs) from mobile source exhaust have contributed to a substantial share of air toxics. In order to characterize the PAHs emissions of diesel engine fueled with diesel, biodiesel (B100) and its blend (B20), an experimental study has been carried out on a direct-injection turbocharged diesel engine. The particle-phase and gas-phase PAHs in engine exhaust were collected by fiberglass filters and “PUF/XAD-2/PUF” cartridges, respectively, then the PAHs were determined by a gas chromatograph/mass spectrometer (GC/MS). The experimental results indicated that comparing with diesel, using B100 and B20 can greatly reduce the total PAHs emissions of diesel engine by 19.4% and 13.1%, respectively. The Benzo[a]Pyrene (BaP) equivalent of PAHs emissions were also decreased by 15.0% with the use of B100. For the three fuels, the gas-phase PAHs emissions were higher than particle-phase PAHs emissions and the most abundant PAH compounds from engine exhaust were naphthalene and phenanthrene. The analysis showed that there was a close correlation between total PAHs emissions and particulate matter (PM) emissions for three fuels. Furthermore, the correlation became more significant when using biodiesel.

Two Euro 4 gasoline passenger vehicles (one gasoline direct injected vehicle and one port fuel injected vehicle) were tested over the cold start New European Driving Cycle (NEDC). Each vehicle was respectively fueled with gasoline and M15 methanol gasoline. Particle number concentrations were measured by the electrical low pressure impactor (ELPI). Particle masses were measured by gravimetric method and estimated from the number distributions using two density distributions (one is constant with the particle size and one is power law related with the size). The first 7 stages of ELPI were used for estimation. The results show that for each vehicle, PM masses measured by gravimetric method, the total PM numbers measured by ELPI and estimated PM masses for M15 are lower than those for gasoline. For each kind of fuel, PM masses by two methods and total PM numbers from the GDI vehicle are higher than those from the PFI one. PM number distribution curves of the four vehicle/fuel combinations are similar. All decline gradually and the maximum number of each curve occurs in the first stage. More than 99.9% numbers locate in the first 8 stages of which diameters are less than 1 μm. PM number emissions correlate well with the acceleration of the two vehicles. The estimated particle masses were much lower than the gravimetric measurements.Highlights► PM masses and numbers from GDI and PFI cars with two kinds of fuels were studied. ► Compared with gasoline, PM masses and numbers with M15 decreased on each car. ► Compared with GDI car, PM masses and numbers from PFI car decreased on each fuel. ► More than 99.9% numbers locate in the first 8 stages of ELPI. ► PM number emissions correlate well with the acceleration of the two vehicles.

AbstractThe types and quantities of volatile organic compounds (VOCs) inside vehicles have been determined in one new vehicle and two old vehicles under static conditions using the Thermodesorber-Gas Chromatograph/Mass Spectrometer (TD-GC/MS). Air sampling and analysis was conducted under the requirement of USEPA Method TO-17. A room-size, environment test chamber was utilized to provide stable and accurate control of the required environmental conditions (temperature, humidity, horizontal and vertical airflow velocity, and background VOCs concentration). Static vehicle testing demonstrated that although the amount of total volatile organic compounds (TVOC) detected within each vehicle was relatively distinct (4940 µg/m3 in the new vehicle A, 1240 µg/m3 in used vehicle B, and 132 µg/m3 in used vehicle C), toluene, xylene, some aromatic compounds, and various C7–C12 alkanes were among the predominant VOC species in all three vehicles tested. In addition, tetramethyl succinonitrile, possibly derived from foam cushions was detected in vehicle B. The types and quantities of VOCs varied considerably according to various kinds of factors, such as, vehicle age, vehicle model, temperature, air exchange rate, and environment airflow velocity. For example, if the airflow velocity increases from 0.1 m/s to 0.7 m/s, the vehicle's air exchange rate increases from 0.15 h−1 to 0.67 h−1, and in-vehicle TVOC concentration decreases from 1780 to 1201 µg/m3.