Influence of Short Carbon-Chain Alcohol (Ethanol and 1-Propanol)/Diesel Fuel Blends over Diesel Engine Emissions

Abstract

Oxygenated fuels, in this case short carbon-chain alcohols, have been investigated as alternative fuels to power compression ignition engines. A major advantage of short-chain alcohols is that they can be produced from renewable resources, i.e., cultivated commodities or biomass-based biorefineries. However, before entering the market, the effects of short-chain alcohols on engine performance, exhaust emissions, noise and sound quality need to be understood. This work sheds light on the relationship between the physicochemical properties of the alcohol/diesel fuel blends (ethanol and 1-propanol) on engine performance, exhaust emissions and, for the first time, on noise and sound quality. It has been demonstrated that when the content of alcohol in blends increased, soot and soluble organic material emissions drastically decreased, mainly due to the increase of oxygen content in the fuel. Reduction in soot emissions combined with higher thermodynamic efficiency of alcohol fuels, with respect to diesel fuel, enable their utilization on compression ignition engines. There is also an improvement in the soot-NOx trade off, leading to large reductions on soot with a small effect on NOx emissions. The oxygen content within the fuel reduces CO and THC emissions at extra-urban driving operation conditions. However, hydrocarbons and CO emissions increased at urban driving conditions, due to the high heat of vaporization of the alcohol fuels which reduces cylinder temperature worsening fuel atomization, vaporization and mixing with air being more significant at lower cylinder temperature conditions (low engine loads and speeds). Similarly, the higher the presence of alcohol in the blend, the higher the noise emitted by the engine due to their low tendency to auto-ignition. The optimization of alcohol quantity and the calibration of engine control parameters (e.g., injection settings) which is out of the scope of this work, will be required to overcome noise emission penalty. Furthermore, under similar alcohol content in the blend (10% v/v), the use of propanol is preferred over ethanol, as it exhibits lower exhaust emissions and better sound quality than ethanol.

Bibliometric Studies on Emissions from Diesel Engines Running on Alcohol/Diesel Fuel Blends. A Case Study about Noise Emissions

“…Table 1. Physiochemical characteristics of diesel fuel and commonly used alcohols to fuel diesel engines [12,13]. 1.…”

“…The author stated that the addition of butanol to diesel fuel increased engine vibration, while combustion noise was 2-3 dB(A) above that of straight diesel fuel. Redel-Macías et al [13] analyzed the influence of adding propanol and ethanol to diesel fuel, in terms of noise. The authors found that the higher the percentage of alcohol in the blend, the higher the engine noise.…”

“…Table 1. Physiochemical characteristics of diesel fuel and commonly used alcohols to fuel diesel engines [12,13]. A brief bibliometric study, including previous works about alcohol/diesel fuel blend emissions, has been carried out, as shown in Figure 1.…”

Separation of the Mixture 2-Propanol + Water by Heterogeneous Azeotropic Distillation with Isooctane as an Entrainer

“…In particular, alcoholic mixtures resulting from bioprocesses can be effectively used as fuel substitutes or additives with a view to increasing the octane number, ensuring a better combustion, reducing harmful exhaust pipe emissions, and thus protecting the environment. Indeed, light alcohols are directly used as a blendstock with gasoline in many countries such as Brazil, Europe and the USA [1]. Among them, ethanol and butanol can be mentioned, which have been proven to reduce life-cycle greenhouse gas emissions when produced from biomass and waste feedstock [2], though some problems are encountered when operating these processes [3,4], and high costs are involved in the downstream product recovery [5,6].…”

“…It is also important to highlight that the use of isooctane as an entrainer can be extremely beneficial in the case of 2-propanol dehydration: traces of such an entrainer do not pose a problem within the recovered dehydrated alcoholic product with a view to its subsequent use as a fuel. [27] New simulation method for three-phase distillation using a modified phase-stability analysis Luyben [24] Process simulation Pienaar [30] Process simulation cyclohexane Gomis et al [45] VLE and VLLE data toluene Gomis et al [62] VLE and VLLE data Zhao et al [31] Process simulation isooctane or 2,2,4-trimethylpentane Cairns and Furzer [27] New simulation method for three-phase distillation using a modified phase-stability analysis Font et al [28] VLE and VLLE data Simulation method 1 Wang et al [26] Experiment using a laboratory-scale sieve plate distillation column; dynamic simulation Chien et al [21] Dynamics and control of a HAD column…”