Experimental Research on the Injection Rate of DME and Diesel Fuel in Common Rail Injection System by Using Bosch and Zeuch Methods

Abstract

This study investigates a preliminary injection characterization of the injection rate and the injection quantity behavior in a high-pressure common rail injection system used in a heavy-duty engine. The injection rate meter and the injection quantity meter used in the test meter measuring systems were jointly connected under the Zeuch method measurement principles at a constant volume chamber and under the Bosch method measurement principles at a long pipe flow. The trade-off trend for the injection rate and the injection quantity was observed according to the injection pressure. As expected, fuel injection with pilot injection affected the spray quantity and the injection evolution of subsequent fuel injection without pilot injection in dimethyl ether and diesel fuel. The pressure variations in the initial injection duration (2000-6000 µs) of the main and pilot injections for diesel and DME were similar. However, after 7000 µs, the pressure of DME increased more rapidly compared to that of diesel. This finding was the result of the rapid density changes caused by the nature of compressive fluid. Therefore, the DME supply pump was expected to require a higher drive energy by approximately 20% compared to that of the diesel supply pump.

Investigation on an Injection Strategy Optimization for Diesel Engines Using a One-Dimensional Spray Model

“…Boundary conditions for solving these equations above are according to Equations (9) and (10): = u 0 (t) = u f (t) (9) = X f,0 (t) = 1 (10) where the subscript "0" means the inlet surface of the first control volume, i.e., the nozzle exit. u f (t) is a cross-section averaged fuel velocity at the nozzle exit and is calculated by Equation (11):…”

“…However, there is little relative research about this. Inversely, as the common used and typical injection rate shapes in diesel engines, scholars have devoted a great deal of effort to the triangle and rectangle as well as trapezoid shapes [9][10][11][12][13]. In order to compare the potential of varying injection rate shapes to lower the pollutant emissions of diesel engines more objectively and comprehensively and find the optimized injection strategy, five injection rate shapes (including triangle, ramping-up, ramping-down, rectangle and trapezoid) were selected in this paper, as shown in Figure 4.…”

“…The shorter the injection duration, the higher the proportion of the ramping part. In the case of a small fuel injection quantity with a short injection duration, the injection rate shape always tends to be triangular [11,12], whose spray mixing characteristics are quite different from that of the commonly used injection rate shapes, like the square, boot or rectangle [9,10,13]. Besides, the advanced innovation of piezoelectric injectors makes a significant contribution to the extremely fast needle response time [14,15], meaning it is easer for diesel engines to adopt highly defined injection rate shapes to improve their performance.…”

“…complicated and crucial mixing process after EOI. Moreover, it is known that there are the ramping-up part during the initial injection period and the ramping-down part during the late injection period in a typical injection rate profile [9,10]. The shorter the injection duration, the higher the proportion of the ramping part.…”

A Study on the Injection Rate Characteristics of the Solenoid Common-Rail Injector Under Using a High-Pressure Fuel System

“…On this aspect, D. Han et al [15] pointed out a higher injection pressure is shorter hydraulic injection delay and prolonger the actual injection duration. Several studies on injection rate under using the common rail system, for instance, F. Boudy and P. Seers [16], X. Seykens et al [17], S. Yang and C. Lee [18], A. Boehman et al [19] brang out the explanation by three effects: the first effect is the difference in injection pressure, due to the synchronization of the pressure wave with the time of injector lifting, the second effect is attributed to the friction coefficient during injection, and the other effect is related to the change of pressure wave amplitude. In addition, the influences of fuel properties on the amount of fuel injection and discharge coefficiency were carried out by D. Han et al [15].…”