No abstract

<div class="section abstract"><div class="htmlview paragraph">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.</div></div>

Knock is the most crucial limitation in attaining the peak load required at high efficiency in heavy duty (HD) spark ignition (SI) engines. Renewable fuels such as ethanol and methanol have high resistance to autoignition and can help overcome this limitation. To reduce knock and improve efficiency further, dilution can be used to add specific heat capacity and reduce combustion temperature. This work studied diluted combustion and knock characteristics of gasoline, ethanol, and methanol on a HD SI single cylinder engine for a wide load range. Ethanol and methanol displayed excellent knock resistance which allowed a peak gross IMEP of 25.1 and 26.8 bar respectively, compared to gasoline which only reached 8.3 bar at [Formula: see text]1.4 with a compression ratio of 13. Over 18% increase in gross IMEP was possible for gasoline and ethanol when increasing air excess ratio from 1 to 1.4. Methanol achieved the target gross IMEP at [Formula: see text]1 and required no spark retard at [Formula: see text]1.6. A peak indicated efficiency above 48% was recorded for ethanol and methanol at [Formula: see text]1.6 and gross IMEP of approximately 21 bar. At part loads, stable operation was possible until [Formula: see text]1.8 for all fuels. Increase in intake temperature showed a marginal improvement in stability but no increase in lean limit. The concept shows promise as diluted combustion of ethanol and methanol reduced knock and achieved diesel baseline load. With optimization, there is potential to improve efficiency further and possible cost savings compared to commercial diesel engines.

No abstract