| 1. |
- Bernemyr, Hanna, et al.
(författare)
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Study of Nozzle Fouling : Deposit Build-Up and Removal
- 2019
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Ingår i: SAE technical paper series. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; :December
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Tidskriftsartikel (refereegranskat)abstract
- The global demand for decreased emission from engines and increased efficiency drives manufactures to develop more advanced fuel injection systems. Today's compression-ignited engines use common rail systems with high injection pressures and fuel injector nozzles with small orifice diameters. These systems are highly sensitive to small changes in orifice diameters since these could lead to deteriorations in spray characteristics, thus reducing engine performance and increasing emissions. Phenomena that could create problems include nozzle fouling caused by metal carboxylates or biofuels. The problems increase with extended use of biofuels. This paper reports on an experimental study of nozzle hole fouling performed on a single-cylinder engine. The aim was to identify if the solubility of the fuel has an effect on deposit build-up and, thus, the reduction in fuelling with associated torque loss, and if there is a probability of regenerating the contaminated injectors. Additionally, the influence of the nozzle geometry was tested by using injectors of various designs. In the experiments, high-load engine operation was used to create the effect of fouling in the presence of zinc-neodecanoate. Solubility properties of the fuel were tested by using high- A nd low-aromatic-content diesel fuels. To gain insight into the morphology and chemical characteristics of the deposits, the nozzles were opened and examined with scanning electron microscopy/energy dispersive X-ray (SEM/EDX). The results showed higher power loss in low-aromatic-content fuels. The experiments also showed regained engine power within an hour using uncontaminated fuel in a fouled nozzle. A three steps process is proposed as the mechanism for deposit build-up and removal in injector nozzles. It is suggested that fouling of the injector is equilibrium between the different steps of the mechanisms.
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| 2. |
- Csontos, Botond, et al.
(författare)
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Characterization of Deposits Collected from Plugged Fuel Filters
- 2019
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Ingår i: SAE technical paper series. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191. ; 2019:September
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Tidskriftsartikel (refereegranskat)abstract
- Fuel filters serve as a safety belt for modern compression ignition engines. To meet the requirements from environmental regulations these engines use the common rail injection system, which is highly susceptible to contamination from the fuel. Furthermore, the public awareness towards global warming is raising the need for renewable fuels such as biodiesel. An increased fuel variety brings a higher requirement for fuel filters as well. To better understand the process of filtration, awareness of the different possible contaminants from the field is needed. This study used several chemical characterization techniques to examine the deposits from plugged fuel filters collected from the field. The vehicle was run with a biodiesel blend available on the market. The characterization techniques included X-ray fluorescence (XRF), Fourier-transform infrared spectroscopy (FTIR) joined with attenuated total reflectance (ATR) sampling, gas chromatography-mass spectrometry (GC-MS), and lastly thermal gravimetric analyzer combined with FTIR and a GC-MS (TGA/FTIR/GC-MS). In addition the remaining ash from TGA was measured in energy-dispersive X-ray spectroscopy (EDX). Deposits were scraped from the used filter, and prepared for the different analytic methods. After cleaning the deposits with different solvents, GC-MS identified the traces of glycerol and sterols in the filter. After a transesterification reaction GC-MS could identify carboxylates corresponding to degraded biodiesel. The TGA/FTIR/GC-MS revealed the presence of polymeric compounds in the deposit. XRF did not require any previous cleaning, and was used to identify different metals present in the deposits. The mentioned deposits are characterized as soft particles, and could originate from the impurities of biodiesel, presence of engine oils, or degradation of the fuel. The presented results help to better understand the current concerns with the on-board filtration of fuels, and can help to create more robust fuel systems in the future.
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