Experimental Investigation of Water Injection Technique in Gasoline Direct Injection Engine

Abstract

This paper experimentally investigates the effect of water injection in the intake manifold on a naturally aspirated, single cylinder, Gasoline Direct Injection engine to determine the combustion and emissions performance with combustion knock mitigation. The endeavor of the current study is to use water injection to attain the optimum combustion phasing without knocking. Further elevated intake air temperature tests were conducted to observe the effect of water injection with respect to combustion and emissions. Experiments were carried out at medium load condition (800 kPa NIMEP, 1500 RPM) at intake air temperatures between 30–90° C in 20° C increments. Two fuels, an 87 AKI and a 93 AKI were used in this study. Baseline tests were undertaken with the high-octane fuel (93 AKI) to achieve optimal combustion phasing corresponding to Maximum Brake Torque (MBT) without water injection. Water injection was utilized for the low octane fuel to achieve combustion phasing of 8–10° ATDC and within the controlled knock limit. Combustion phasing was achieved by controlling the ignition timing, water injection quantity and timing to the knock threshold. The results showed that water injection and the resultant charge cooling mitigates combustion knock and an optimum combustion phasing based on indicated fuel conversion efficiency is achieved with a water to fuel ratio of 0.6. Water injection reduces the NOx emissions while achieving better indicated thermal efficiency compared to the baseline tests. A detailed comparison is presented on the combustion phasing, indicated thermal efficiency, burn durations, HC, NOx and PN emissions in this paper.

Experimental Investigation on Gasoline—Water Mixture Fuel Impingement Preparation Method and Spray Characteristics with High Injection Temperatures and Pressures

“…Water is a substance with a large latent heat of evaporation and stable chemical reaction characteristics. Introducing water into the combustion chamber as a working medium and using the characteristics of water evaporation and heat absorption to significantly reduce the temperature in the cylinder flow can effectively optimize the combustion phase and reduce the knock tendency [18][19][20][21][22][23]. Water injection technology, therefore, has great potential in improving thermal efficiency and in reducing emissions.…”

Knock Suppression of a Spark-Ignition Aviation Piston Engine Fuelled with Kerosene

“…The knock suppression was increased for a mass ratio of water over fuel as 0.3 [16]. An experimental study based on a single-cylinder engine indicated that fuel with a lower octane number could be used if port water injection was installed [17]. Kim et al performed an experiment, and water was sprayed into the cylinder in a pressure of 5 MPa using a gasoline direct injection (GDI) fuel injector.…”

Effects of Vessel and Water Temperatures on Direct Injection in Internal Combustion Rankine Cycle Engines

“…This technology [4] also leads to a significant gain in the knock-limiting ignition timing advance and decrease in the compression end temperature, as well as the temperature when the exhaust valve is open. Mahankali et al [5] found that injecting water into the intake manifold also mitigated combustion knock, and they achieved an optimum combustion phasing based on the indicated fuel conversion efficiency with a water-to-fuel ratio of 0.6. Port water injection [6] could help engines operate under full load with a stoichiometric air-fuel ratio, and this resulted in up to a 5% improvement in net mean effective pressure and an improvement in thermal efficiency from 25 to 34% at 3000 rpm.…”