A Study of Supercharged HCCI Combustion Using Blended Fuels of Propane and DME 2014-32-0005
Homogeneous Charge Compression Ignition (HCCI) has attracted a great deal of interest as a combustion system for internal combustion engines because it achieves high efficiency and clean exhaust emissions. However, HCCI combustion has several issues that remain to be solved. For example, it is difficult to control engine operation because there is no physical means of inducing ignition. Another issue is the rapid rate of heat release because ignition of the mixture occurs simultaneously at multiple places in the cylinder. The results of previous investigations have shown that the use of a blended fuel of DME and propane was observed that the overall combustion process was delayed, with that combustion became steep when injected propane much.
This study focused on expanding the region of stable engine operation and improving thermal efficiency by using supercharging and blended fuels. The purpose of using supercharging were in order to moderated combustion. In addition, the purpose of using blended gaseous fuels were find out effective use of gaseous fuels. Low-carbon gaseous fuels with clean emissions were used as the test fuels. The specific fuels used were dimethyl ether (DME, cetane number of 55 or higher) that exhibits pronounced low-temperature oxidation reactions. Propane (cetane number of 5) that does not exhibits low-temperature reaction readily and that is a principal component of liquefied petroleum gas. A spectroscopic measurement technique was used to investigate the combustion in detail by obtain the light emission spectra of the combustion flame. The characteristics of the reaction products were investigated by analyzing the exhaust gas components using Fourier transform infrared spectroscopy.
The results shows that the quantity of DME and propane ratio injected determines the ignition timing, the engine load level can be adjusted by means of the quantity of propane injected to achieve ignition near top dead center. In addition, combustion became moderate by supercharging.