INJECTION AND SPRAY CHARACTERISTICS OF BLENDS OF DIESEL FROM DIRECT COAL LIQUEFACTION AND PETRODIESEL

Abstract

As a new commercial fuel, diesel from direct coal liquefaction (DDCL) has different physical and chemical properties from petrodiesel. The injection and spray characteristics of DDCL petrodiesel and their blends are investigated with a common rail system using EFS method and high-speed photography, respectively. The results show that DDCL proportion hardly influences start of injection but has significantly influences on the end of injection especially in the case of wide injection pulse width. The injection duration lengthens with DDCL proportion and the rise of setting rail pressure inhibits the lengthening. Maximum injection rate increases linearly and rapidly with setting rail pressure, and also increases with injection pulse width, first rapidly then slowly, but does not vary with DDCL proportion. The slope of injection rate versus setting rail pressure declines as IPW lengthens. The relative phase of maximum injection rate is delayed with increasing injection pulse width. But it remains unchanged or advances as setting rail pressure increases. At the same setting rail pressure, average injection rate increases first rapidly then slowly with prolonged injection pulse width; the average injection rate of DDCL is larger than that of petrodiesel. The penetrations of spray remain almost constant in all blends. However, the steady cone angle increases with an increase in DDCL proportion. The spray tip penetration of DDCL-petrodiesel blends is prolonged by higher setting rail pressure, longer IPW, and lower ambient pressure. The steady cone angle is enlarged by higher setting rail pressure and ambient pressure.