Study of Fuel Temperature Effects on Fuel Injection, Combustion and Emissions of Direct-Injection Diesel Engines

Abstract

The influence of inlet liquid fuel temperature on direct-injection diesel engines can be noticeable and significant. The work in this paper investigates the effects of inlet fuel temperature on fuel injection, in-cylinder combustion, and performance and emissions of medium-speed diesel engines. An enhanced understanding and simplified modeling of the variations in main fuel injection parameters affected by inlet fuel temperature are developed. The study indicates that the main affected injection parameters include the injector injection timings, the fuel injection rate, the fuel injection duration, and the injection spray atomization. The primary fuel temperature effects on the injection parameters are from the fuel bulk modulus of elasticity and the density with the fuel viscosity less significant as the injector nozzle flow is in a turbulent region. The developed models can predict the changes in the injection parameters versus fuel temperature. As inlet fuel temperature increases, the nozzle fuel-injection-start timing is predicted to be retarded, the injection rate to be reduced, and the needle-lift duration to be prolonged from the baseline. The variation trends of the engine performance and emissions versus fuel temperature are analyzed by considering its consequent effect on in-cylinder combustion processes. It is predicted that raising fuel temperature would result in an increase in CO, HC, PM and smoke emissions, and in a decrease in NOx. The experimental results of the output performance and emissions from testing a medium-speed four-stroke diesel engine agreed with the trends analytically predicted. The understanding and models developed can apply to compression-ignition direct-injection liquid fuel engines in general.

Investigation of the effect of heated ethanol fuel on combustion and emissions of an ethanol direct injection plus gasoline port injection (EDI + GPI) engine

“…When the ethanol fuel temperature is increased from 50°C to 90°C, the density of the ethanol fuel decreases from 763 to 721 kg/m 3 , viscosity decreases from 0.676 to 0.374 mPa s, and surface tension decreases from 0.0202 to 0.0152 N/m [34]. Experiments and simulations on the fuel injection process showed that, when the fuel temperature was increased, the actual injection timing was retarded, the peak rail pressure was decreased and the injection duration was prolonged [32,35]. The fuel mass flow rate was decreased with the increase of fuel temperature because of the decreased fuel density [24,36,37].…”

Investigation on Combustion and Emission Performance of a Common Rail Diesel Engine Fueled with Diesel/Biodiesel/Polyoxymethylene Dimethyl Ethers Blends

“…In the mechanical injection system, the bulk modulus of fuels, mainly controlled by environmental temperature, 53 tends to affect the injection timing and thus the NOx emissions. 54,55 For a common-rail injection system, the change of compressibility derived from the speed of sound and the bulk modulus of blend fuels does not influence the injection timing. 51,56 Neither diesel nor PODE has C−C double bonds in the molecule structure, but the cetane number of diesel/ biodiesel/PODE blend fuels is obviously higher than that of D100.…”

Investigation of the injection process and combustion of a dimethyl ether engine with different nozzle flow areas

“…In this study, three types of nozzle with d h = 0.31 mm, 0.35 mm, and 0.4 mm, respectively were used. Further, since the fuel temperature shows marked effects on the fuel injection process [14], the DME inlet temperature was stabilized to 30°C, and this will be discussed further in this paper.…”

“…It has been proved that the fuel injection parameters have shown pronounced effects on the fuel injection process and the engine combustion characteristics [10][11][12][13][14]. However, there have been few reports in the literature concerning the DME injection process.…”