The impact of alcohol admixture with gasoline on carbon build-up and fuel injectors performance

Abstract

The operating conditions of injectors in spark ignition engines with direct fuel injection make them susceptible to coking, which leads to a reduced quality of fuel atomization. This can be observed by a drop in performance and an increase in exhaust emissions, especially particulate matter. One effective method of reducing injector coking is by using detergentdispersing gasoline additives. The article describes the effect of using an admixture with a varied alcohol content on the quantitative and qualitative fuel atomization indicators. The research consisted of a 48-hour engine test, done in accordance with the CEC F-113-KC procedure (CEC-F-113 test). After each test cycle, the injectors underwent optical tests with the use of an isochoric chamber. The spray penetration and surface area were analyzed at a set of different fuel injection parameter values. The research performed resulted in determining the influence of each tested admixture on the change of injection time and on the geometric indicators of the fuel spray. The obtained characteristics of the engine in operation and conducted stationary tests enabled the operational evaluation of the impact an alcohol admixture with gasoline fuels had on key engine parameters.

Potential of ethanol and butanol in reducing deposits of DISI engine injectors

“…Direct fuel injection generally allows for better mixture formation than indirect injection engines. The significance of the fuel injection process in a DISI-type engine arises from several factors, including the higher fuel injection pressure, precise control over injection pressure variations, and the timing and quantity of fuel delivery [3,23]. The formation of the fuel-air mixture is contingent upon various aspects, such as the internal structure of the liquid stream, the atomization process, and fuel evaporation characteristics [21][22][23].…”

“…The significance of the fuel injection process in a DISI-type engine arises from several factors, including the higher fuel injection pressure, precise control over injection pressure variations, and the timing and quantity of fuel delivery [3,23]. The formation of the fuel-air mixture is contingent upon various aspects, such as the internal structure of the liquid stream, the atomization process, and fuel evaporation characteristics [21][22][23]. Notably, the internal structure of the jet stream during injection plays a pivotal role as it directly influences the jet atomization process and vaporization properties [13,14,21].…”

“…Notably, the internal structure of the jet stream during injection plays a pivotal role as it directly influences the jet atomization process and vaporization properties [13,14,21]. Generating any deviation or disturbance in the optimized atomized fuel spray pattern, such as: changing the jet angle, disturbing the assumed atomization symmetry of the spray pattern, increasing the penetration, or increasing the average diameter of atomized fuel droplets, has a deteriorating effect on engine emissions and performance [20,23]. The formation process of the combustible mixture in the engine cylinders is prone to interference, influenced by several critical factors.…”

“…Consequently, this gives rise to elevated emissions of harmful exhaust constituents, accompanied by heightened fuel consumption, diminished engine performance, erratic operation, and challenges initiating the engine [3]. Even a small amount of deposits formed in the channels and around the outlet ports of the fuel injectors of DISI engines uncontrollably changes both quantitatively and qualitatively the injection process by limiting the magnitude of the fuel outflow rate from the injector [14,25], distorting the spray pattern of the jets [14], deteriorating the quality of the spray [25], and adversely interacting the fuel jets with the turbulence of the air supplied to the combustion chambers [3,23]. In the latest designs of reciprocating internal combustion engines, including the DISI type, preventing the formation of injector deposits has a decisive impact on the engine's maintenance of the manufacturer's declared performance characteristics as well as performance and emissions.…”

“…Deposits forming in the injector outlet channels affect the flow rate, jet penetration depth and spray cone angle and the start and end of injection. They can change the injectors' spray characteristics, which, in turn, can affect the engine cylinder's charge formation and combustion processes [3,11,[21][22][23]26]. External coke deposits around the injector outlet ports are mainly formed from burnt fuel and, to a lesser extent, from lubricating engine oil.…”