The paper presents results of co-combustion of diesel-biodiesel-ethanol fuel blend in direct injection Diesel engine. Test was performed at constant rotational speed at three commonly used loads of this engine: 100%, 85%, and 70% of load. During the test hydrated ethanol was used at a concentration of 89% of alcohol. In this study, the ethanol fuel was added to diesel-biodiesel fuel blend with concentrations up to 50% with the increment of 5%. The biodiesel was used as an additive to prevent the stratification of ethanol and diesel blends. Thermodynamic parameters of engine were analyzed, and combustion process and exhaust emission were characterized. It turned out that with the increase in engine load is possible to utilize larger ethanol fraction in blend. With the increase of ethanol fuel in blend the increase in ignition delay (38.5% for full load) was observed, but burning duration decreased (49% for full load). The ethanol fuel share in blend generally causes the increase in NO x emission (42% for full load) due to higher oxygen content and higher in-cylinder temperatures. It turned out that, at full load the unrepeatability of indicated mean effective pressure was near the same up to 50% of ethanol fuel in blend (about 2%). In case of partial load at higher ethanol fuel fraction the increase in indicated mean effective pressure un-repeatability was observed.
The motivation of the paper is an attempt to indicate the relationship between the selected Gas Tungsten Arc Welding (GTAW) technology and the parameters of the boundary conditions for the simulation of the heat treatment process of elements made of medium-carbon steel. The authors of the paper prepared and described a series of numerical simulations and experimental studies concerning this problem. Simulations often use previously-developed analytical equations to describe the relationships between process parameters. The results obtained for the input data for determining the heat source power (voltage) from the analytical equation and experimental measurements were compared. Several cases of the size of the areas of direct influence of the GTAW arc (various radius of a simulation heat source) were analysed. All computations were performed in the author’s software based on Finite Element Method (FEM) solving the heat transfer equation with the convection term. In this paper, the GTAW heating parameters (boundary condition) for a current intensity equal 30 A were identified. With the assumed arc efficiency coefficient, the arc voltage set on the device and the measured value of the arc current, the optimum radius of the heat source was determined. The identification of parameters was confirmed by the convergence of the results of numerical simulation in three-dimensional space (3D) with the results of the experiment. Unfortunately, the applied methodology did not give good results for current equal to 50A.
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