Abstract
This paper summarizes a study based on a modified, light, single-cylinder diesel engine and the effects of the physicochemical properties for n-butanol-diesel blended fuel on the combustion process and hydrocarbon (HC) emissions in the intake at a medium speed and moderate load in, an oxygen-rich environment (Coxy = 20.9–16%), an oxygen-medium environment (Coxy = 16–12%), and an oxygen-poor environment (Coxy = 12–9%). The results show that the ignition delay period is the main factor affecting the combustion process and it has a decisive influence on HC emissions. In an oxygen-medium environment, combustion duration affected by the cetane number is the main reason for the difference in HC emissions between neat diesel fuel (B00) and diesel/n-butanol blended fuel (B20), and its influence increases as the intake oxygen concentration decreases. In an oxygen-poor environment, in-cylinder combustion temperature affected by the latent heat of vaporization is the main reason for the difference in HC emissions between B00 and B20 fuels, and its influence increases as the intake oxygen concentration decreases. By comparing B20 fuel with diesel/n-butanol/2-ethylhexyl nitrate blended fuel (B20 + EHN), the difference in the ignition delay period caused by the difference in the cetane number is the main reason for the difference in HC emissions between B20 and B20 + EHN fuels in oxygen-poor environment, and the effect of this influencing factor gradually increases as the intake oxygen concentration decreases.
Highlights
When a low-reactivity fuel [1] is blended with a high reactivity fuel such as diesel [2], the fuel’s alcohol properties are modified, which improves efficiency and clean combustion, and it has attracted attention
To analyze the influence of the physicochemical properties of n-butanol-diesel blended fuel on HC emissions based on the intake oxygen concentration, the intake oxygen concentration was divided into an oxygen-rich environment, an oxygen-medium environment, and an oxygen-poor environment according to the trend of HC generation at different intake oxygen concentrations
At the same oxygen concentration, the HC value generated by B20 fuel is slightly greater than that by B00 fuel, and as the intake oxygen concentration decreases, the difference in HC emissions of the two fuels varies from 0.13 g/(kW·h) to 0.31 g/(kW·h)
Summary
When a low-reactivity fuel [1] is blended with a high reactivity fuel such as diesel [2], the fuel’s alcohol properties are modified, which improves efficiency and clean combustion, and it has attracted attention. Such methods inevitably bring an increase in HC emissions, and some believe that the latent heat of vaporization of fuel is one of the main factors affecting HC emissions. The test results showed that, at all engine loads, the higher latent heat of vaporization of n-butanol and 1-pentanol leads to an increase in HC emissions compared to diesel. Armas et al [6]
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