Cold starting test of a high pressure common rail diesel engine was conducted on an engine test bench simulating plateau environment with high altitudes and low temperature. A comprehensive study of ...cold starting and idling performance was investigated under plateau ambient temperature of-35°C to-10°C and altitude ranged from 2km to 4km. Results show that, without inlet air heating, during engine starting up under different altitude at-10°C, average inlet temperature and pressure can drop slightly and idling rotating speed exhibits strong fluctuation. By heating up inlet air for 60 seconds, the inlet temperature shows statistically linear growing trend in the first 8 heating seconds, during which period averaged inlet temperature rises to 12.4°C, thus obviously lifting up intake temperature, improving engine starting up performance and reducing rotating speed fluctuation. At high altitude and cold plateau conditions, by prolonging the air heating time solely has limited effects on reducing engine starting up time or improving cold starting performance, nor can rotating speed fluctuation been effectively reduced. When ambient temperature reaches-30°C, by heating up inlet air for the same specified time interval, an average of temperature rise of 2.4°C can be obtained for altitude step increase of 1 kilometer, but cold starting up performance has not been therefore significantly improved.
Concerns about effects of particulate control technologies applied on in-use diesel vehicles on atmospheric environment prompted more measurements and analytical methods needed to assess ...environmental implication. An on-board particulate sampling and measurement system were used to test the particulate-phase compositions from the diesel buses retrofitted with catalyzed diesel particulate filter (CDPF) or a diesel oxidation catalyst coupled with a CDPF (DOC & CDPF) under real-world road, operating on a typical urban circuit in Shanghai of China. Based on fuel basis emission factors, CDPF and DOC & CDPF were most effective in reducing 2-, 3- and 4-ring polycyclic aromatic hydrocarbons (PAHs), above 90%, followed as to 5-ring PAHs, ~70%. The aftertreatments showed significant effective in reducing the Benzoapyrene equivalent (BaPeq) of 3-ring PAHs, while presenting lower reduction rate for the BaPeq of 4- and 5-ring PAHs. The BaPeq with higher toxic equivalent factor (TEF) dominated in total BaPeq even the buses with aftertreatments. DOC & CDPF had slight advantage in reducing PAHs and their toxicity than the sole CDPF. The reduction rates of organic carbon (OC) and elemental carbon (EC) emissions factors were ~84% and ~98%, with OC/EC ratio ranging from ~1 to ~11. The particle number, mass and surface area factors were reduced by the aftertreatments, with reductions of up to 95%. According to particles diameter classification, the aftertreatments slightly influenced the percentage distributions. Whatever the buses without or with aftertreatments, it.s found that the particles of DP=0.05 um dominate in the total PN factor, the particles of 0.587% in the total PM factor, and the particles of 0.0592% in the total PSA factor, which are important in determining and increasing particulate toxicity.
One of the key issues facing the low compression ratio engine is the start difficulty, especially at high altitude. And coolant temperature is an important parameter, which would affect misfire and ...instability of diesel engine combustion during start. An experimental study of heating coolant temperature to improve start performance and effect of coolant temperature on the combustion characteristics of low compression diesel engine during start at different altitudes was carried out. Tests were led on a mid-speed heavy-duty intercooled-turbocharged diesel 14.25:1 CR (compression ratio) engine, whose intake and exhaust pressure was controlled by the plateau simulation test system to stimulate the altitude conditions including 0 m, 3000 m and 4500 m. The results indicated that, the effect of coolant temperature on the start performance and combustion characteristics of low compression diesel engine was more significant at higher altitude. There was a -3.72%, 14.83% and 48.74% average reduction in the time of start-up period for every 20 ? rose in coolant temperature at the altitude of 0m, 3000m, 4500m. The main pattern of combustion during start of different coolant temperatures was single parent peak under plain condition (0 m) with stronger combustion stability and better acting ability. But at the altitude of 3000 m and 4500m, when the cooling water temperature was low, there was an ignition difficulty in the cranking period, and there are misfire cycles and larger pressure fluctuation in the start-up period. The ratio of the single parent peak cycle was increased and the cycle of misfire and afterburn disappeared in speed-up phase with the increase of coolant temperature, the IMEP (Indicated Mean Effective Pressure) was increased and the speed-up phase was shortened. There was a 2.78%?18.52% and 29.76% average increase in the ratio of the single peak type cycle of start and a -0.05bar,1.52 bar and 1.91 bar average increase in IMEP for every 20 ? rose in coolant temperature at the altitude of 0 m, 3000 m and 4500 m. Regarding the combustion characteristics of idle condition, there was a 2.14°CA, 3.85°CA and 4.5°CA average advance in The crank angle position for peak pressure and a 4.79%, 6.06% and 7.38% shortening in combustion duration for every 20 ? rose in coolant temperature at the altitude of 0m, 3000m and 4500m.
The fuel economy and pollutant emissions characters of diesel taxies in Shanghai were analyzed. In particular, the fuel consumption and fuel cost per 100 kilometers, turnover, traveled distance, ...service kilometers, empty-loaded rate, and CO, NO X , HC+NO X , PM emissions characteristics of diesel taxies were carried out. The analysis result shown that compared with gasoline taxies, the fuel consumption and fuel cost per 100 kilometers of diesel taxies were reduced by 29% and 26% respectively. Diesel taxies will get more traveled distance, further service kilometers, and added turnover, whereas lower empty-loaded rate and less fuel cost per 100 kilometers. Among the total 120,000 kilometers test distance, the CO emission of diesel taxies was lower than the limited value of China national emission standard IV, the NOX and HC+NOX emission is under the limited value of China national emission standard III, whereas, the PM emission was under the limited value of China national emission standard II. All of CO, NO X , HC+NO X , and PM emissions of diesel taxies were reduced obviously when fuel by Shanghai IV diesel after 1 st November, 2009.
The emissions characteristics of a diesel car fueled by biodiesel volume ratio of 10% (called BD10), which is the mixture of conventional diesel and waste oil based biodiesel, was carried out. And ...the emission characteristics of HC, CO, NO x and CO 2 in different driving mode and different driving cycle in accordance with the "I" type test cycle of Chinese vehicle emission standard GB18352.3-2005 was analyzed. The results shown that compared with the idling, constant speed, and deceleration driving modes, the accelerated driving mode's HC, CO, NO X emissions of BD10 fueled diesel car is relatively high. The HC and CO emissions of the first urban operation cycle, and the CO 2 and NO x emissions of suburban operation cycle are higher than others operation cycles of the "I" type test cycle of GB18352.3-2005. Compared with conventional diesel, the HC, CO, NO x , CO 2 emissions of BD10 fueled diesel car are reduced by 6%, 1%, 10% and 2% respectively.
Emulsified diesel is an alternative fuel for internal combustion engines. It can reduce the emitted pollutants. In this work, the effect of water-oil emulsions on the particulate matter (PM) and ...particle-phase polycyclic aromatic hydrocarbons (PAH) composition exhausted by diesel engine was studied. Three different water-oil blends emulsions with volume fractions of water ranging from 0% to 15% were investigated. The experimental results indicated that the mean reductions of PM mass concentration of E10, E15 are 19.31% and 17.99%, respectively, compared with E0.The mean increases of total PAH content of E10, E15 are 5.08% and 20.19%, respectively, compared with E0. The BaPeq (benzo a pyrene equivalent toxicity) of E0, E10 and E15 are 4.75, 6.53 and 8.86 respectively. Therefore, the blending fraction is a significant factor for the particle-phase total PAH content. Besides, researches on health effects of emulsified diesel are needed as well.
