Exhaust Particle Number Concentrations Research Articles

Influence of negative corona discharge on the Zeta potential of diesel particles.

Electrical agglomeration as a pretreatment means can reduce the exhaust particle number concentration of diesel engine. The charge of particle is an important factor affecting the coagulation process. Therefore, an experiment was carried out to study the charging characteristic of diesel particles. Zeta potential for diesel particle was used to represent the charged state and the charge of particles could be calculated according to the value of Zeta potential. Influences of various factors on the charge of particle were investigated by changing the charged voltage, internal temperature of charging zone, and the load of engine. Experimental results show that the increase of charged voltage can improve the charge and the absolute value of diesel particles. With increase of charging zone temperature, corona inception voltage declines and the charge of particle increases. The load of engine has a positive effect on the charge of particles which reaches its peak at full load.

The formation and physical properties of the particle emissions from a natural gas engine

Natural gas engine particle emissions were studied using an old gasoline engine modified to run with natural gas. The tests were steady-state tests performed on two different low loads in an engine dynamometer. Exhaust particle number concentration, size distribution, volatility and electric charge were measured. Exhaust particles were observed to have peak diameters below 10nm. To get the full picture of particle emissions from natural gas engines, size range 1–5nm is relevant and important to take into consideration. A particle size magnifier (PSM) was used in this engine application for measuring particles smaller than 3nm and it proved to be a useful instrument when measuring natural gas engine exhaust particles. It is concluded that the detected particles probably originated from the engine cylinders or their vicinity and grew to detectable sizes in the sampling process because a small fraction of the particles were observed to carry electric charge and the particles did not evaporate totally at 265°C.

Effects of fresh lubricant oils on particle emissions emitted by a modern gasoline direct injection passenger car.

Particle emissions from a modern turbocharged gasoline direct injection passenger car equipped with a three-way catalyst and an exhaust gas recirculation system were studied while the vehicle was running on low-sulfur gasoline and, consecutively, with five different lubrication oils. Exhaust particle number concentration, size distribution, and volatility were determined both at laboratory and on-road conditions. The results indicated that the choice of lubricant affected particle emissions both during the cold start and warm driving cycles. However, the contribution of engine oil depended on driving conditions being higher during acceleration and steady state driving than during deceleration. The highest emission factors were found with two oils that had the highest metal content. The results indicate that a 10% decrease in the Zn content of engine oils is linked with an 11-13% decrease to the nonvolatile particle number emissions in steady driving conditions and a 5% decrease over the New European Driving Cycle. The effect of lubricant on volatile particles was even higher, on the order of 20%.

An investigation of diesel–ignited propane dual fuel combustion in a heavy-duty diesel engine

This paper presents a detailed experimental analysis of diesel–ignited propane dual fuel combustion on a 12.9-l, six-cylinder, production heavy-duty diesel engine. Gaseous propane was fumigated upstream of the turbocharger air inlet and ignited using direct injection of diesel sprays. Results are presented for brake mean effective pressures (BMEP) from 5 to 20bar and different percent energy substituted (PES) by propane at a constant engine speed of 1500rpm. The effect of propane PES on apparent heat release rates, combustion phasing and duration, fuel conversion and combustion efficiencies, and engine-out emissions of oxides of nitrogen (NOx), smoke, carbon monoxide (CO), and total unburned hydrocarbons (HC) were investigated. Exhaust particle number concentrations and size distributions were also quantified for diesel–ignited propane combustion. With stock engine parameters, the maximum propane PES was limited to 86%, 60%, 33%, and 25% at 5, 10, 15, and 20bar BMEPs, respectively, either by high maximum pressure rise rates (MPRR) or by excessive HC and CO emissions. With increasing PES, while fuel conversion efficiencies increased slightly at high BMEPs or decreased at low BMEPs, combustion efficiencies uniformly decreased. Also, with increasing PES, NOx and smoke emissions were generally decreased but these reductions were accompanied by higher HC and CO emissions. Exhaust particle number concentrations decreased with increasing PES at low loads but showed the opposite trends at higher loads. At 10bar BMEP, by adopting a different fueling strategy, the maximum possible propane PES was extended to 80%. Finally, a limited diesel injection timing study was performed to identify the optimal operating conditions for the best efficiency-emissions-MPRR tradeoffs.

Effects of injection parameters and EGR on exhaust soot particle number-size distribution for diesel and RME fuels in HSDI engines

The exhaust soot particles number size distributions obtained from the combustion of diesel and RME fuels were investigated in a high speed direct injection (HSDI) diesel engine for different engine operating conditions viz., fuel injection pressure, injection timing, exhaust gas recirculation (EGR) and engine load. An Electrostatic Mobility Spectrometer (EMS) was used for characterising the exhaust soot particle number size distribution. Increasing the fuel injection pressure reduced the particle size and its number concentration in the accumulation mode under low and high load conditions, but an opposite trend was observed to the particle number concentration in the nucleation mode under higher load operation. The effect of fuel injection timings on the particle number concentration was not clear and consistent between diesel and RME fuels under low load operation. Under high load operation, the overall particle number concentration for RME decreased but for diesel only the nucleation mode decreased, while the accumulation mode remained unaltered when the fuel injection timing was retarded. The addition of EGR caused the particles to agglomerate and form larger size particles, which were observed mostly in the accumulation mode. Under most of the engine operating conditions RME emitted lower soot particle concentration than diesel under both nucleation and accumulation modes. The presence of oxygen in the fuel has the potential to lower the exhaust particle number concentration in diesel engines.

Evaluation of a condensation particle counter for vehicle emission measurement: Experimental procedure and effects of calibration aerosol material

A limit on particle number emission from the exhaust of Euro 5/6 engines will take effect in 2011 and engine exhaust particle number concentrations are required to be measured by particle number counters that meet requirements set forth by the UN/ECE particulate measurement programme (PMP). The TSI Model 3790 engine exhaust condensation particle counter (EECPC) was developed to meet these PMP requirements. This paper describes an experimental study that evaluated the performance of the EECPC. Experimental setup and procedures for calibrating EECPCs were evaluated. It was found that the EECPC counting efficiency strongly depended on the aerosol material. Among several materials tested, the counting efficiencies were highest for poly-α-olefin and lowest for sodium chloride. Errors in the concentration measurement due to the aerosol material dependence were estimated and found to be significant. Considerations for selecting aerosol materials for EECPC calibration are discussed with regard to best match with engine testing conditions.

Incidence of bacterial bronchitis in children with chronic wet cough: the analysis of 203 bronchoscopies

A limit on particle number emission from the exhaust of Euro 5/6 engines will take effect in 2011 and engine exhaust particle number concentrations are required to be measured by particle number counters that meet requirements set forth by the UN/ECE particulate measurement programme (PMP). The TSI Model 3790 engine exhaust condensation particle counter (EECPC) was developed to meet these PMP requirements. This paper describes an experimental study that evaluated the performance of the EECPC. Experimental setup and procedures for calibrating EECPCs were evaluated. It was found that the EECPC counting efficiency strongly depended on the aerosol material. Among several materials tested, the counting efficiencies were highest for poly-α-olefin and lowest for sodium chloride. Errors in the concentration measurement due to the aerosol material dependence were estimated and found to be significant. Considerations for selecting aerosol materials for EECPC calibration are discussed with regard to best match with engine testing conditions.

Effects of Combustion Mode on Exhaust Particle Size Distribution Produced by an Engine Fueled by Dimethyl Ether (DME)

Exhaust particle (10−487 nm) number size distributions (NSDs) from an engine fueled with dimethyl ether (DME) for three combustion modes [compression ignition direct injection (CIDI), homogeneous charge compression ignition (HCCI), and compound charge compression ignition combustion (CCCI)] were tested and compared. The results indicated that the NSD for various combustion modes showed similar unimodal structure with a nucleation mode at all test engine conditions. The exhaust particle geometric mean diameters of CCCI and HCCI were within the same range, and they were around 4−7 nm bigger than those of CIDI. Under the same engine condition (1100 revolutions/min, 20% of full load), the total exhaust particle number concentrations for CCCI (rp = 0.18−0.85) were slightly lower than those of HCCI but 20.0−29.3% higher than those of CIDI. For CCCI, the total number decreased with the increase of the load at the same premixing ratios but increased significantly with the increase of the premixing ratio at the sa...

Experimental studies on particle emissions from cruising ship, their characteristic properties, transformation and atmospheric lifetime in the marine boundary layer

Abstract. Particle emissions from ship engines and their atmospheric transformation in the marine boundary layer (MBL) were investigated in engine test bed studies and in airborne measurements of expanding ship plumes. During the test rig studies, detailed aerosol microphysical and chemical properties were measured in the exhaust gas of a serial MAN B&W seven-cylinder four-stroke marine diesel engine under various load conditions. The emission studies were complemented by airborne aerosol transformation studies in the plume of a large container ship in the English Channel using the DLR aircraft Falcon 20 E-5. Observations from emission studies and plume studies combined with a Gaussian plume dispersion model yield a consistent picture of particle transformation processes from emission to atmospheric processing during plume expansion. Particulate matter emission indices obtained from plume measurements are 8.8±1.0×1015(kg fuel)−1 by number for non-volatile particles and 174±43 mg (kg fuel)−1 by mass for Black Carbon (BC). Values determined for test rig conditions between 85 and 110% engine load are of similar magnitude. For the total particle number including volatile compounds no emission index can be derived since the volatile aerosol fraction is subject to rapid transformation processes in the plume. Ship exhaust particles occur in the size range Dp<0.3 μm, showing a bi-modal structure. The combustion particle mode is centred at modal diameters of 0.05 μm for raw emissions to 0.10 μm at a plume age of 1 h. The smaller-sized volatile particle mode is centred at Dp≤0.02 μm. From the decay of ship exhaust particle number concentrations in an expanding plume, a maximum plume life time of approx. 24 h is estimated for a well-mixed marine boundary layer.

Characteristics of ultrafine particles emitted from a dimethyl ether (DME) engine

Measurements of exhaust particle number concentration and size distribution from a dimethyl ether (DME) engine at different engine loads and speeds were carried out by using a two-stage dilution system and an SMPS. The results of the DME engine were compared with those of the original diesel engine. The fuel composition had significant effects on the exhaust particle size distribution, the total exhaust particle number and mass concentrations. Compared with those of the DME engine, the particle mass emissions of the diesel engine increased 5.7–17.7 times. At high engine speed (n=2200 r/min), compared with those of the DME engine, the total particle number emissions of the diesel engine increased 0.75–2.2 times, while the total particle number emissions of the diesel engine decreased by about 50%–80% for middle and high loads at middle engine speed (n=1400 r/min). Compared with those of the DME engine, the total exhaust particle number concentrations in the accumulation mode of the diesel engine increased 4.2–62.6 times and the exhaust particle geometric number mean diameters in the accumulation mode increased by about 10–30 nm. This correlated with higher oxygen level and lack of C-C bonds in DME. A lot of nucleation mode particles were emitted from the DME engine, this correlated with the processes of nucleation and condensation of the volatile and semi-volatile compounds in the exhaust gas.

Particle size distribution from a GTL engine

Measurements of exhaust particle number concentration and size distribution from an engine fueled with GTL at different engine loads and speeds were carried out by using a two-stage dilution system. The results for GTL were compared with those from the original engine fueled with diesel. The fuel composition and engine operation condition had significant effects on the exhaust particle size distribution, the total exhaust particle number and volume concentrations. For both fuels, the load had no significant influence on the total exhaust particle number concentration at middle speed, while the total exhaust particle number concentration increased with the increase of the load at high speed. At 1400 rpm and 2200 rpm, the total exhaust particle volume concentration increased as the load increased for both fuels. GTL was found to be a "cleaner" fuel. Compared with diesel, under the same operation conditions, the total exhaust particle number concentrations decreased 18-92%, and the total exhaust particle volume concentrations for GTL decreased 21-59%.

On-road evaluation of two Diesel exhaust aftertreatment devices

Two Diesel particulate matter emission control devices; the continuously regenerating trap ( CRT TM ) and the catalyzed continuously regenerating trap ( CCRT TM ) were evaluated using a mobile emissions laboratory. The source of emissions was the lab's engine that was fueled with 15 ppm sulfur fuel, and specially formulated, low sulfur (1300 ppm) lubrication oil. The objective was to characterize performance using real-time aerosol instrumentation, real-world dilution, and on-road driving conditions. The devices when combined with low S fuel and lube oil effectively removed Diesel particulate matter. The CRT produced large quantities of nuclei mode particles, the quantity of which increased as a function of exhaust temperature. The CCRT reduced the exhaust particle number concentration to levels not detectable above background storage sites, thus eliminating precursors that form nuclei mode particles. Use of low S fuel and lubrication oil prolongs the storage process. Over time it is expected that this material would be released.