AN ASSESSMENT OF VARIOUS NANOADDITIVES AND TRIBO-CORROSION WITH WASTE COOKING BIODIESEL FUELED IN A DIESEL ENGINE

The waste cooking biodiesel's steady-state coefficient of friction rate of fuel blends are B90 (18.2%), B60 (7.2%), B20 (16.72%), B10 (30.8%), and diesel (38.77%) higher compared with B40 fuel blend and wear scar diameter of the fuel blends from B40 to B100 had a minimal range of 0.5mm. The flash temperature parameter results higher from B40 to B100 fuel blends, and the corrosion rate was minimal for B40 and B50 fuel blends. Afterward, the fuel blend B40 (40% WCO+60% Diesel fuel) was chosen as fuel, along with Cerium (25ppm), Zinc (25ppm), and Titanium nanoparticles (25ppm) were selected as fuel additives. The B40+D60+Titanium (25ppm) blend resulted in improved BTE and 3.83% lowered BSEC comparison with diesel fuel. Then the fuel blend, B40+D80+Titanium (25ppm), resulted in 2.08% reduced HC, 36.36% CO, and 16.25% smoke emissions, along with marginally 8.5% higher NOx emissions comparison with diesel fuel. Also, the fuel blend, B40+D80+Titanium (25ppm) combustions characteristics are the equivalent trend of cylinder pressure (58.82 bar) and HRR (66.65 J/deg CA) related to diesel fuel at peak load.

A Multi-scale Contact Temperature Model for Dry Sliding Rough Surfaces

A multi-scale flash temperature model has been developed and validated against existing work. The core strength of the proposed model is that it can be adapted to predict flash contact temperatures occurring in various types of sliding systems. In this paper, it is used to investigate how different surface roughness parameters affect the flash temperatures. The results show that for decreasing Hurst exponents as well as increasing values of the high-frequency cut-off, the maximum flash temperature increases. It was also shown that the effect of surface roughness does not influence the average interface temperature. The model predictions were validated against data from an experiment conducted in a pin-on-disc machine. This also showed the importance of including a wear model when simulating flash temperature development in a sliding system.

EXPERIMENTAL STUDIES OF THE RELATIONSHIP BETWEEN THE BOILING TEMPERATURE AND THE FLASH TEMPERATURE OF MIXED HYDROCARBON FUELS

В работе экспериментально показано, что по мере испарения смесевой горючей жидкости при одновременном повышении плотности и снижении упругости пара в многокомпонентных взаиморастворимых композициях температура кипения повышается. В этом случае и температура вспышки смесевой горючей жидкости также будет повышаться. Так, при проливах горючих жидкостей происходит довольно быстрое обеднение легкими фракциями, упругость пара при заданной температуре существенно снижается, а температуры кипения и вспышки, соответственно, повышаются. Полученные в работе зависимости температур кипения и вспышки испытанных смесевых горючих жидкостей характерны и для других различных многокомпонентных жидких композиций. Эти зависимости могут учитываться при разработке планов предотвращения и ликвидации аварий в случае их проливов. Based on the experiments it is shown that as the flammable liquid mixtures evaporate, while increasing density and decreasing vapor tension in multicomponent compositions-soluble, the boiling temperature increases. In this case, the flash point of the mixed combustible liquid will also increase. Thus, in the case of spills of flammable liquids there is a fairly rapid depletion of light fractions, the vapor tension at a given temperature reduces significantly, and the boiling and flash temperatures increase accordingly. The dependences of the boiling and flash temperatures of the tested mixed combustible liquids obtained in this work are also typical for other various multicomponent liquid compositions. These dependencies can be taken into account when developing plans for the prevention and elimination of emergencies caused by their spills.

Tensile strength and thermal cycle analysis of AA6061 friction weld joints with different diameters and various friction times

The paper reports measurement of tensile strength and the thermal cycle of AA6061 aluminum alloy circular bar friction weld with different diameters and various friction times. A continuous drive friction welding (CDFW) of AA6061 was conducted to weld the AA6061 circular bar with different diameters of 30 mm for the rotating part and 15 mm for the stationary part. The CDFW process was carried out with the revolution speed of 1,600 rpm, the initial compressive force of 2.8 kN during the friction stage for various friction times of 10, 12, and 14 seconds, and an upset force of 28 kN for 60 seconds. The flash temperature was measured using a digital infrared thermometer gun. Computer simulation using the finite element method was also done by coupling transient thermal and static structural methods. The flash temperature becomes higher along with increasing friction time based on the digital infrared thermometer gun measurement and finite element analysis. The results of tensile strength testing show that the specimen with a friction time of 12 seconds has the highest tensile strength. Based on the hardness testing result, it is found that the specimen with a friction time of 10 seconds has higher hardness, but it has an incomplete joint flash so that the tensile strength is lower than that of the specimen with a friction time of 12 seconds. Besides, the hardness of the specimen with a friction time of 12 seconds is higher than that of the specimen with a friction time of 14 seconds. The flash size becomes bigger along with the increase of the friction time based on the macrostructure observation on the longitudinal section of the CDFW specimen. It is confirmed by the temperature measurement and finite element analysis that the specimen with a friction time of 12 seconds has heat input to form the CDFW joint that has a maximum tensile strength in the range of this study

Analytical Determination of the Brake Temperature Mode During Repetitive Short-Term Braking

An algorithm to determine the maximum temperature of brake systems during repetitive short-term (RST) braking mode has been proposed. For this purpose, the intermittent mode of braking was given in the form of a few cyclic stages consisting of subsequent braking and acceleration processes. Based on the Chichinadze’s hypothesis of temperature summation, the evolutions of the maximum temperature during each cycle were calculated as the sum of the mean temperature on the nominal contact surface of the friction pair elements and temperature attained on the real contact areas (flash temperature). In order to find the first component, the analytical solution to the one-dimensional thermal problem of friction for two semi-spaces taking into account frictional heat generation was adapted. To find the flash temperature, the solution to the problem for the semi-infinite rod sliding with variable velocity against a smooth surface was used. In both solutions, the temperature-dependent coefficient of friction and thermal sensitivity of materials were taken into account. Numerical calculations were carried out for disc and drum brake systems. The obtained temporal variations of sliding velocity, friction power and temperature were investigated on each stage of braking. It was found that the obtained results agree well with the corresponding data established by finite element and finite-difference methods.

Dynamic Model for Friction-Induced Oxidation of Metals in Dry Sliding Processes

Oxidative mechanisms in tribological processes are commonly related with temperature and the real contact area. In this article, a lumped parameter dynamic model was developed to predict friction-generated oxide thicknesses in dry sliding conditions. The proposed model is based on conservative principles and causal equations applied to a pin-on-disk configuration in order to calculate the flash temperature with base on the heat transfer phenomena. Also, a mass balance was proposed to estimate the amount of hematite (Fe2O3), magnetite (Fe3O4), and wüstite (FeO) formed by friction heat. A new equation was proposed to predict the thicknesses of the oxides generated, and the model was validated based on experimental data available in specialized literature.