No abstract

Complex research into the change of parameters concerning the fuel economy, thrust, and harmful components of exhaust gases, namely, hydrocarbons (HC), carbon monoxide (CO), and nitric oxides (NOx), was carried out to evaluate the efficiency of fuel replacement; that is, mineral diesel fuel, which is normally used by diesel engine fleets of agricultural machinery in Lithuania, was replaced with biofuel (hereafter biodiesel), which is rapeseed oil methyl esters, hereafter RME. Diesel engine F2L511 and a single section of diesel engine A41 were chosen as models and tested within the above-mentioned research parameters. Fuel blends of mineral diesel fuel and RME-biodiesel fuel, and also pure RME, were tested as follows:  BI0, in which the content of RME is 10%; B15 and B30, in which the contents of RME are 15% and 30% appropriately; and Bl00, which is pure RME. A nonlinear change of operational characteristics was determined depending on the loads of the diesel engine. According to its technical ecological parameters, B30-biodiesel fuel was acknowledged as the most convenient and reliable one being tested within a wide range of speed and load regimes. In the same range of speed and load regimes, the influence of technical conditions of the fuel injector on harmful emission parameters of diesel engine exhaust gases, while running on RME, was estimated by means of a failure simulation of the fuel injector, namely, gumming up the fuel injector nozzle. An improvement of all the ecological parameters was estimated by optimization of the diesel engine injection timing while running on RME.

The publication research task is related to one of the solution aspects in reference to decarbonization of transport by transferring the operation of diesel engines to natural gas. The results of converted diesel engines into operation with dual-fuel (D-NG) without significant constructive modifications are focused on forecasting the energy efficiency parameters of in-service engine models and evaluation of the reserves improvement. This paper presents energy efficiency parameters and characteristics of the combustion cycle methodological optimization of high-speed 79.5/95.5 mm diesel engine with a conventional fuel injection system. Interrelations between the indicated efficiency (ηi), combustion cycle performance parameters (excess air ratio (α), compression ratio (ε), degree of pressure increase in the cylinder (λ), maximum cycle pressure (pmax), air pressure (pk), air temperature (Tk) after compression, etc.), and heat release characteristics were determined and researched. Directions of the optimization when the engines were operating in a wide range of load (pmi) modes were also obtained: the low energy efficiency in the low-load mode were due to reduced heat release dynamics (combustion time increased up to 200° CA). The main influencing factors for ηi were the pilot-injection portion phase (φinj) and α, optimization of ε was inefficient. To avoid exceeding the permissible limits of reliability for pmax, the realized reserve of ηi increase was estimated as 10%. Methodological tools for the practical application of parametric analysis to the conversion of diesel to dual-fuel operation have been developed and adapted in the form of a numerical modeling algorithm, which was presented in nomogram form. For improvement of initial energy parameters for a specific engine models heat release characteristics identification, accurate methods must be used. The proposed methodology is seen as a theoretical tool for a dual-fuel conversion models for in-service engines and has benefit of a practical use of a fast application in the industrial field.

This paper highlights the results of scientific research on the possibility of increasing the biofuel concentration in the fuel used in diesel engines by introducing bioethanol in multicomponent diesel fuel mixtures containing fossil diesel fuel (D), rapeseed oil methyl esters (RME), and ethanol (E).In the initial stage of the research, we performed an analysis of the physicochemical parameters of fuel and comparative tests of a diesel engine running on pure fossil diesel fuel, rapeseed oil methyl esters (RME), and RME-E mixtures. In engine tests, it has been shown that increasing the ethanol amount in biodiesel fuel up to 40% leads to an increase in indicator index η i of the tested diesel engine 1A41 by 2.5%. CO and NO x emissions decreased up to 10-12% for every 10% increase of ethanol amount in blend with rapeseed oil methyl esters. The influence of different levels of ethanol on CO and NO x emissions from fuel and on experimentally defined dynamics of the indicator process can show alternative improvements of the performance characteristics of the diesel engine while working on fuel mixtures.

To expand the raw materials base for the production of biodiesel fuel, it is advantageous to make use of biobutanol (B) produced from renewable resources, which can be used in two ways as fuel for diesel engines: by direct inclusion into multicomponent fuel for diesel engines or by producing fatty acid butyl esters from rapeseed oil. Multicomponent fuels D70/B30, D70/B15/RME(RBE)15, and D50/B25/RME(RBE)25 meet the standards for fossil diesel fuel (D) and biodiesel fuel in terms of the main indicators of quality. When 30% biocomponents are included in a mixture with fossil diesel fuel, the effective efficiency factor of the engine (ηe) is as high as that of pure fossil diesel fuel, and reductions are achieved in the emission of all harmful components (CO, HC, NO x , and BSN). Usage of a such mixture is more promising if compared with a mixture containing higher content of biocomponents. Increase of biocomponents to 50% causes an increase in ηe of up to 4% compared to that of fossil diesel fuel, reduction in emissions of CO and BSN, and little change in the level of NO x and HC emissions. Also, the three-component fuel containing rapeseed butyl esters has better qualities than fuel containing rapeseed methyl esters. The introduction of biobutanol in three-component mixture instead of ethanol is more promising due to the better performance and environmental characteristics of the fuel.