Potential Improvement in PM-NOX Trade-Off in a Compression Ignition Engine by n-Octanol Addition and Injection Pressure

Abstract

n-Octanol, as an oxygenated fuel, is considered as one of the most promising alternative fuels, owing to advantages such as its low hygroscopic nature, high cetane number, and high energy content. However, the introduction of n-octanol leads to a higher viscosity and latent heat of evaporation (LHOE), affecting the combustion and emission performances of compression ignition (CI) engines. This study sheds light on the effect of injection pressures (IPs, ranging from 60 to 160 MPa) on the combustion and emission performances of a turbocharged CI engine, in conjunction with n-octanol/diesel blends. According to the proportion of oxygen content, the test fuels contain pure diesel (N0), N2.5 (2.5% oxygen content in the blending fuels), and N5 (5% oxygen content in the blending fuels). The results indicate that the blending fuels have little influence on the in-cylinder pressure, ignition delay (ID), and CA50, but they improve the brake thermal efficiency (BTE). In terms of emissions, with the use of blending fuels, the levels of carbon monoxide (CO), soot, and nitrogen oxides (NOX) decrease, whereas emissions of hydrocarbons (HC) slightly increase. With increasing IP, the ID, brake specific fuel consumption (BSFC), HC, CO, and soot decrease significantly, and the BTE and NOX increase. In addition, the combination of n-octanol and IP improves the trade-off between NOX and soot and reduces the CO emissions.

Experimental Investigation on the Effect of Graphene Oxide in Higher Alcohol Blends and Optimization of Injection Timing Using an ANN Method

“… 28 Wang and colleagues discovered that the diesel–octanol blends exhibited the best BTE and lowest BSFC when the injection pressure was 120 MPa. 29 Regarding emissions, the lowest particle number was observed at an injection pressure of 100 MPa. The optimal balances of combustion and emission outcomes were attained at an injection pressure of 100–120 MPa.…”

“…The study also revealed that an increase in octanol proportions led to a higher BTE and a decrease in brake-specific fuel consumption (BSFC) . Wang and colleagues discovered that the diesel–octanol blends exhibited the best BTE and lowest BSFC when the injection pressure was 120 MPa . Regarding emissions, the lowest particle number was observed at an injection pressure of 100 MPa.…”

Predicting Sooting Propensity of Oxygenated Fuels Using Artificial Neural Networks

“…Another method is to blend the fuels with selective oxygenate additives, such as alcohols and ethers, that can reduce soot formation during combustion. A number of studies have shown that oxygenates, such as methanol [10][11][12], ethanol [10,13,14], n-butanol [15,16], n-octanol [17], dimethyl ether [18], polyoxymethylene dimethyl ether (PODE) [19][20][21][22], and diethyl ether [23][24][25], can reduce soot formation in IC engines. The propensity of oxygenated compounds to reduce soot is not only dependent on the oxygen content, but also strongly depends on the molecular structure, as shown by a number of works [26][27][28][29][30][31].…”

Hydraulic Interactions between Injection Events Using Multiple Injection Strategies and a Solenoid Diesel Injector

“…NOx and soot emissions are the main pollutants from diesel engine, which are regulated by emissions standards [1][2][3]. There are several ways to fulfil these regulations, such as the use of alternative fuels [4][5][6], changes in the piston bowl geometry [7,8], increase in injection pressure [9,10], and the use of multiple injection strategies such as pilot injection strategy, post-injection strategy and split injection strategy, which consist of dividing the injection into two pulses [11]. The duration between the two pulses is called dwell time (DT) [12].…”