Abstract
Many studies of DiMethyl Ether (DME) as an alternative fuel in Compression-Ignition (CI) engines have been performed. Although diverse DME engine research has been conducted, the investigation of combustion behavior and temperature distribution in the combustion engine has not progressed due to the fact that there is no sooting flame in DME combustion. In order to investigate the combustion characteristics in this study, the KIVA-3 V code was implemented to research various pilot injection strategies on a single-cylinder CI engines with DME and Ultra-Low-Sulfur Diesel (ULSD) fuels. The combustion distribution results obtained from the numerical investigation were validated when compared with the measurement of flame temperature behaviors in the experimental approach.This study showed that long intervals between two injection timings enhanced pilot combustion by increasing the ambient pressure and temperature before the start of the main combustion. Different atomization properties between DME and ULSD fuels contributed to the formation of a fuel-air mixture at the nozzle tip and piston lip regions, separately, which strongly affected the temperature distribution of the two fuels. In addition, the pilot injection timing played a vital role in regard to ignition delay and peak combustion temperatures. Exhaust emissions, such as NOx and soot, are related to the local equivalence ratio and temperature in the combustion chamber, also illustrated by the contrary result on a Φ (equivalence ratio) – T (temperature) map.
Highlights
As the quality of human life increases, many people are concerned with their health and the environment
Pre-combustion reduced the main combustion temperature as well as premixing the first injection, which did not form a fuel-rich mixture. This numerical investigation was performed to verify the effects of various pilot injection timings on the combustion behavior of DiMethyl Ether (DME) and Ultra-Low-Sulfur Diesel (ULSD) fuels in terms of combustion pressure, heat release rate, and temperature distribution, which were undetectable in the experimental approach
The KIVA-3 V code implemented numerical experiments of various injection conditions fueled with DME and ULSD and drew the results as follows: 1. The span between the pilot injection timing and the main timing strongly affected combustion characteristics
Summary
As the quality of human life increases, many people are concerned with their health and the environment. Yoon et al [5] studied the effects of pilot injection on DME combustion and emission in a single-cylinder Direct-Injection CompressionIgnition (DICI) engine. The DME engine with an EGR system achieved lower NOx emissions than the Euro IV limit, and suggested that an additional oxidation catalyst can reduce CO and HC simultaneously. Among these methods to lower exhaust emissions, a pilot injection strategy is available in conventional Diesel engine fueled with DME without any modification. A previous study [7] carried out analytical research on the DME combustion and emission under single-injection conditions, and showed high prediction results as compared with experiments. A multi-dimensional grid was generated based on the AVL 5402 engine
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