Search Results

Low Temperature Combustion (LTC) is an emerging technology that offers an alternative to conventional spark and compression ignition. A highly discussed LTC mode is homogeneous charge compression ignition (HCCI), which consists in a combustion of a highly diluted well-mixed charge at the end of compression stroke, when the charge reaches the auto-ignition state. Since HCCI is an LTC mode, it can result in low NOX emissions with an indicated efficiency comparable to a diesel engine. Otherwise, there are some challenges to overcome such as achieving high loads without knocking and combustion timing control. Several methods to control the combustion had been investigated, between them, the injection of water may be useful to extend HCCI knock free operation and to enable combustion phasing control. This work investigated the influence of water injection in the intake of an ethanol HCCI cylinder from a converted diesel generator set.

Using Exhaust Gas Recycling (EGR) on internal combustion engines enables the reduction of emissions with a low or even no cost to the engine efficiency at part-load operation. The charge dilution with EGR can even increase the engine efficiency due to de-throttling and reduction of part load pumping losses. This experimental study proposed the use of late exhaust valve closure (LEVC) to achieve internal EGR (increased residual gas trapping). A naturally aspirated single cylinder direct injection spark ignition engine equipped with four electro-hydraulic actuated valves that enabled full valve timing and lift variation. Eight levels of positive valve overlap (PVO) with LEVC were used at the constant load of 6.0 bar IMEP and the speed of 1500 rpm. The results have shown that later exhaust valve closure (EVC) required greater intake pressures to maintain the engine load due to the higher burned gases content. Hence, lower pumping losses and thus higher indicated efficiency were obtained.

Global warming and pollutant emission concerns have been driving research towards cleaner and environmentally friendly fuels. Like ethanol, butanol is a promising biofuel with characteristics such as higher calorific value and lower latent heat of vaporization. Due to its similar properties to those of gasoline, butanol stands as a potential gasoline surrogate. Butanol can be produced from through the ABE (acetone–butanol–ethanol) fermentation process, which uses bacterial fermentation to produce acetone, n-Butanol, and ethanol from carbohydrates such as starch and glucose. This work presents the experimental results of a single-cylinder spark ignition research engine equipped with port fuel injection. Several compression ratios were compared via spacer rings. Fuels as n-butanol, hydrous ethanol (E95W05) and their blends were evaluated in comparison to primary reverence fuel (isooctane).

The current quest for clean and renewable fuels has prompted the appearance of several bio-mass fuel alternatives. Ethanol is a renewable biofuel obtained from different agricultural crops. The main production process to obtain anhydrous ethanol consists of crop production, mashing and cooking, fermentation, distillation and chemical dehydration. Some attractive characteristics of ethanol as a clean energy source is the CO2 absorption through photosynthesis during the crop plantation phase and positive ethanol life cycle energy balance. Even though, ethanol production cost is still relatively high when compared to fossil fuels. Knowing that a large energy amount is spent in the distillation phase, the use of hydrous ethanol as fuel, with high water content, can be economically attractive. This paper compares the use of high water-in-ethanol volumetric content fuel, varying from 5% to 40%, in a naturally aspirated 0.668-L single-cylinder port-fuel injected spark-ignited engine.