| 1. |
- Andersson, Öivind, et al.
(författare)
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Crank Angle Resolved HC Detection Using LIF in the Exhausts of Small Two-Stroke Engines Running at High Engine Speed
- 1996
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Ingår i: SAE Transactions, Journal of Engines. - 0096-736X. ; 105:961927
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Tidskriftsartikel (refereegranskat)abstract
- In order to separate the HC-emissions from two-stroke engines into short-circuit losses and emissions due to incomplete combustion, Laser Induced Fluorescence (LIF) measurements were performed on the exhaust gases just outside the exhaust ports of two engines of different designs. The difference between the two engines was the design of the transfer channels. One engine had "finger" transfer channels and one had "cup handle" transfer channels. Apart from that they were similar. The engine with "finger" transfer channels was earlier known to give more short-circuiting losses than the other engine, and that behavior was confirmed by these measurements. Generally, the results show that the emission of hydrocarbons has two peaks, one just after exhaust port opening and one late in the scavenging phase. The spectral information shows differences between the two peaks and it can be concluded that the latter peak is due to short-circuiting and the earlier due to incomplete combustion. The flow outside the exhaust port was measured with Laser Doppler Velocimetry (LDV). These measurements confirm the occurrence of two emission peaks.
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| 2. |
- Ekenberg, Martin, et al.
(författare)
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Biological reduction of hexavalent chromium - A field study
- 2005
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Ingår i: Water Environment Research. - 1061-4303. ; 77:4, s. 425-428
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Tidskriftsartikel (refereegranskat)abstract
- When ferrochromium is produced at Vargon Alloys AB (Vargon, Sweden), an offgas dust is generated as a byproduct. A leachate that contains hexavalent chromium (Cr6+) is formed when rainwater percolates through the dust deposit. In this study, Cr6+ in the leachate was reduced to trivalent chromium (Cr3+) by biological treatment in a biofilm process operated under anaerobic conditions. The reactor volume was 26 m(3) and it was filled with 16 m(3) plastic packing. Acetic acid was added as an electron donor. The Cr6+ Was reduced from 10 to 20 mg/L to below 0.03 mg/L when the reactor was operated at a hydraulic retention time of 11 hours. The reduction activity in the process gradually decreased as the water temperature dropped below 10 degrees C.
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| 3. |
- Ekenberg, Martin
(författare)
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In-Cylinder Fluid Flow, Fuel Preparation and Combustion in SI Engines - Application of Optical Diagnostics
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis laser-based measurements of in-cylinder flow and fuel concentrations in two stroke and direct injected four-stroke engines are presented. The major problem with the carburetted two-stroke engine is the short-circuiting of fuel that occurs during the scavenging phase. This leads to large emissions of unburned hydrocarbons. The object of this thesis has been to map the flow behaviour in two-stroke engine cylinders during the scavenging phase, and to detect differences between different cylinder designs. The measurement techniques which have been utilised are Laser Doppler Velocimetry (LDV), Laser Induced Fluorescence (LIF) and Mie scattering from fuel droplets, LSDI. Of these measurement methods, LDV and LSDI have been used inside the cylinder. LIF was used outside the exhaust port. The second object of this thesis has been to map fuel distribution, in cylinder flow and combustion in an air assist direct injected four-stroke engine. For the fuel distribution measurements, PLIF was used. The flow measurements were performed with PIV, and flame photography was used to map flame development / combustion. All two-stroke measurements were performed in engines running at their rated speeds, 9000 rpm for three of the designs and 5800 rpm for one design. All engines were run at full load with combustion. For the two-stroke engine measurements, it was found that: „h The LDV measurements inside the cylinders show that cylinders with cup handle transfer channels have a flow pattern inside the cylinder that gives less short-circuiting, and hence less emissions of hydrocarbons, than the cylinder with open transfer channels. „h The LIF measurements outside the exhaust port show that the HC emissions that are caused by short-circuiting comes earlier in the scavenging phase for the cylinder with open transfer channels than is the case for the cylinders with cup handle transfer channels. „h The LSDI measurements in the cylinder provide the transfer channel flow angle, for the cylinders with cup handle transfer channels. For the cylinder with open transfer channels, the results are not as useful; fuel droplet vaporisation close to the exhaust port ruins the results. Measurements in the four-stroke engine showed: „h For the direct injected four-stroke engine, in-cylinder fuel distribution was measured with PLIF. Results show that stratification of fuel is feasible with late injection timings in combination with bowl-in-piston. „h PIV measurements of the flow show that late injection increases the level of in-cylinder flow velocities, that inevitably break down into turbulence. „h Flame photographs of the combustion in a stratified charge mode show two different kinds of combustion; one primary, premixed combustion and one diffusion combustion.
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| 4. |
- Ekenberg, Martin, et al.
(författare)
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The Effect of Transfer Port Geometry on Scavenge Flow Velocities At High Engine Speed
- 1996
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Ingår i: SAE Special Publications. - 0148-7191. ; :SP-1131
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Konferensbidrag (refereegranskat)abstract
- 2-D LDV measurements were performed on two different cylinder designs in a fired two-stroke engine running with wide-open throttle at 9000 rpm. The cylinders examined were one with open transfer channels and one with cup handle transfer channels. Optical access to the cylinder was achieved by removing the silencer and thereby gain optical access through the exhaust port. No addition of seeding was made, since the fuel droplets were not entirely vaporized as they entered the cylinder and thus served as seeding. Results show that the loop-scavenging effect was poor with open transfer channels, but clearly detectable with cup handle channels. The RMS-value, "turbulence", was low close to the transfer ports in both cylinders, but increased rapidly in the middle of the cylinder. The seeding density was used to obtain information about the fuel concentration in the cylinder during scavenging.
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| 5. |
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