The Effect of Water Injection on the Control of In-Cylinder Pressure and Enhanced Power Output in a Four-Stroke Spark-Ignition Engine

Abstract

This paper presents the results for liquid water injection (WI) into a cylinder during the compression and expansion strokes of an internal combustion engine (ICE), with the aim of achieving an optimal in-cylinder pressure and improving power output using CFD simulation. Employing WI during the compression stroke at 80 • of crank angle (CA) before top dead centre (bTDC) resulted in the reduction of compression work due to a reduction in peak compression pressure by a margin of about 2%. The decreased peak compression pressure also yielded the benefit of a decrease in NOx emission by a margin of 34% as well as the prevention of detonation. Using WI during the expansion stroke (after top dead centre-aTDC) revealed two stages of the in-cylinder pressure: the first stage involved a decrease in pressure by heat absorption, and the second stage involved an increase in the pressure as a result of an increase in the steam volume via expansion. For the case of water addition (WA 3.0%) and a water temperature of 100 • C, the percentage decrease of in-cylinder pressure was 2.7% during the first stage and a 2.5% pressure increase during the second stage. Water injection helped in reducing the energy losses resulting from the transfer of heat to the walls and exhaust gases. At 180 • CA aTDC, the exhaust gas temperature decreased by 42 K, 89 K, and 136 K for WA 1.0, WA 2.0, and WA 3.0, respectively. Increasing the WI temperature to 200 • C resulted in a decrease of the in-cylinder pressure by 1.0% during the first stage, with an increase of approximately 4.0% in the second stage. The use of WI in both compression and expansion strokes resulted in a maximum increase of in-cylinder pressure of about 7%, demonstrating the potential of higher power output.

Numerical Simulation of a Reactivity Controlled Compression Ignition Engine in order to Investigate the Effects of Adding Water to Low Reactivity Fuel

“…With increasing the water mass fraction to 15%, the quality of combustion decreases significantly, because the number of water and gasoline moles in this mass fraction, are almost equal, and since both of these materials, affect the combustion process equally, water absorbs some of the combustion heat and it decreases the combustion quality. According to Figures 15 and 7, it can be observed that in the mass fraction of 20%, the pressure rise is not due to the increase of combustion quality because the CO and CO2 emission levels are not significantly changed; thus as it was indicated before, this pressure rise can be due to the higher number of water moles in the combustion chamber [43].…”

Improving Fishermens Welfare with Fuel-Saving Technology

“…Water injection helped in reducing the energy losses resulting from the transfer of heat to the walls and exhaust gases [21]. So, Brown's Gas has 3 main functions, is: (1) Save fuel, and increase mileage per liter; (2) Minimize emissions which are the main cause of the greenhouse effect; and (3) Improve engine performance and strength.…”

One-Dimensional Simulation Using Port Water Injection for a Spark Ignition Engine

“…This is because less energy is required to compress the charge air. This advantage should be significant in high compression ratio engine due to the increase of in-cylinder pressure at the latter stage of compression stroke [15]. Besides the reduction of compression work, the reduced pressure also helps to reduce the suction gas losses result from blow-by past the piston rings [14].…”

“…There are some simulation works that are worth to be highlighted [3,4,7,[12][13][14][15]. Since this paper is related to numerical approach, only the prior studies which used numerical approach is highlighted.…”

“…Breda et al [3] also utilised the CFD simulation to study the effect of different injection content, namely pure methanol, pure water and 25%, 50%, and 75% of methanol to water, to the spark ignition engine. Wei et al [15] assessed the direct WI via CFD simulation and the author injected the water at the compression stroke and expansion stroke separately. Wei et al found that the WI in both compression and expansion stroke exhibits the potential of higher power output from the increase of in-cylinder pressure by about 7%.…”