Effect of various ignition timings on combustion process and performance of gasoline engine

This article deals with the effect of the ignition timing on the output parameters of a spark-ignition engine. The main assessed parameters include the output parameters of the engine (engine power and torque), cylinder pressure variation, heat generation and burn rate. However, the article also discusses the effect of the ignition timing on the temperature of exhaust gases, the indicated mean effective pressure, the combustion duration, combustion stability, etc. All measurements were performed in an engine test room in the Department of Technology and Automobile Transport at Mendel University in Brno, on a four-cylinder AUDI engine with a maximum power of 110 kW, as indicated by the manufacturer. To control and change the ignition timing of the engine, a fully programmable Magneti Marelli control unit was used. The experimental measurements were performed on 8 different ignition timings, from 18 CA to 32 CA BTDC at wide throttle open and a constant engine speed (2500 rpm), with a stoichiometric mixture fraction. The measurement results showed that as the ignition timing increases, the engine power and torque also increase. The increase in these parameters is a reflection of higher pressure in the cylinder, the maximum value of which is achieved at a higher ignition timing near top dead centre in thepower stroke. In these conditions we can expect higher engine efficiency. It was also found that the combustion is more stable with a higher value of ignition timing. No significant difference was found in the combustion duration.O

The impact of upper link length on the output parameters of a tractor set

The aim of the article is to find out the impact of the increase in the force in the upper link of a three-point hitch on the performance parameters of the tractor set Claas Arion and the carried plough Pöttinger equipped with a traction roller and the cultivator Väderstad. During aggregation of the tractor with the plough with an average increase in the force in the upper link of a three-point hitch by 25 kN, a decrease of slippage in average by 8.25 %, a decrease in fuel consumption by 1.875 ml / m3 and an increase in effective performance by 0,225 m3 / s were achieved. During aggregation of the same tractor with the carried cultivator with an increase in the force by 40 kN, an average decrease in slippage by 2.64 %, a decrease in effective fuel consumption by 2 l / ha and an increase in effective performance by 0.6 ha / h were achieved. The changes in the observed parameters were demonstrably influenced by the change in the force in the upper link, which was more significantly shown during the aggregation of the tractor with the plough equipped with a traction booster.O

Drawbar Pull and Its Effect on the Weight Distribution of a Tractor

This article aims to experimentally determine how the tractor's weight distribution changes during loading by drawbar pull, and how the tractor's weight affects its drawbar pull properties. Drive wheel ballasting has a significant effect on the drawbar pull and wheel slip of the tractor - travelling gear losses. To achieve these objectives, we conducted experimental measurements on the tractor Case IH Magnum 370 CVX. The results show that higher drawbar pull is achieved in tractors with a higher weight. The measured increase of drawbar pull was 15,8 kN between maximal and minimal weight (Δ 2320 kg). All variants show an equal percentage increase in the weight on the rear axle of the tractor (+ 6 %). Increasing the tractor's weight affected the drawbar pull as well as the wheel slip. As the tractor's weight increases, there is a smaller increase in wheel slip as the drawbar pull increases. The results confirmed that tractor ballasting is important in order to achieve optimum drawbar pull properties, but it is necessary to keep in mind that the higher the weight of the machine or equipment, the larger the effect on the soil.O

The Effect of the Tractor Tires Load on the Ground Loading Pressure

The contribution, based on the experimental measurement, analyses the issue of a specific pad loading pressure in relation to radial wheel load and tire inflation. Tile inflation in terms of allowed radial load, which we wish to be high as far as possible in terms of the power transmission from the wheels to the ground is important for the field tensile works, on the other hand, the pressure in the tire is closely related to the contact area and ground loading pressure. The obtained results show the following: Michelin Multibib 650/65 R38 tire, inflated to a pressure of 80 kPa has a sufficient reserve in radial load. As the measurement results show, ground loading pressure at the highest load of 36.55 kN, which was used during the measurement, is under the value of 100 kPa, which would mean on loamy soil at a humidity of 17 % that the limit of the ground pressure on the ground has not been exceeded.O

Rheological behaviour of chocolate at different temperatures

The rheological behaviour of the chocolate at different temperatures was studied using a concentric cylinder viscometer with precision small samples adapter, temperature sensor and standard spindle. BIO chocolate (100% organic cocoa) has been used for the whole types of experiments. At the first, the range of temperature has been chosen 36 oC, 38 oC, 40 oC, 42 oC, and 44 oC. The shear deformation rate was established from the 0.1 s-1 up to 68 s-1. Rheological behaviour was non-Newtonian (plastic) with inconsiderable yield stress in all temperatures. The chocolate unambiguously demonstrated plastic behaviour and flow curves were fitted by the power law model (Herschel-Bulkley model), Bingham model, and Casson model with taking into account the coefficient of determination R2. The obtained results of rheological behaviour of chocolate can be best described as Casson fluid. Exactly coefficients of models can be used for modelling of flow velocity, volume flow, friction factor, Reynolds number, two dimensional and three dimensional velocity profiles and much more for flow in the real technical elements e.g. pipes, trough, tubes. Finally, temperature dependence of apparent viscosity of chocolate was also continuously measured in the range from 35 oC up to 62 oC. The apparent viscosity decreased in the temperature range. This decrease was fitted using power law equation. The knowledge of the plastic flow behaviour of chocolate is very important, because it is not quite common flow behaviour of foodstuffs.O

UPOTREBA BILJNOG ULJA ZA MOTORE

Vegetable oils are a very important component in human and animal nutrition. Furthermore, they represent potential fuels for engines as well. These fuels named as biofuels are renewable energy sources which must gradually replace today’s conventional fuels made from crude oil. The higher energy demands in production and problems which arise during their combustion are the main disadvantages of biofuels. Vegetable oils made from rape seeds belong to the most used biofuels for diesel engines in the Czech Republic. The article describes use of rapeseed oil, methyl esters of rapeseed oil (RME) and their mixture with diesel fuel (B30) in diesel engines, their ecological benefits in combustion and necessary modification of some elements in engines. Data used for evaluation were obtained from measurements in the vehicle laboratory. The results were compared with the diesel fuel. As results show, evaluated biofuels have a positive impact on exhaust emissions of engines but at higher consumption.Biljna su ulja vrlo važan sastojak u prehrani ljudi i životinja. Osim toga, predstavljaju i potencijalna goriva za motore. Ta su goriva, zvana biogoriva, obnovljivi izvori energije što mogu postepeno nadomjestiti današnja uobičajena goriva iz sirove nafte. Potrebe za više energije u proizvodnji i problemi koji nastaju za vrijeme izgaranja glavni su nedostaci biogoriva. Biljna ulja iz uljne repice pripadaju među najviše upotrebljavana biljna ulja za dizel motore u Češkoj Republici. Članak opisuje upotrebu repičinog ulja, metil estera iz repičinog ulja (RME) i njihovu mješavinu s dizel gorivom (B30) u dizel motoru, njihove dobre ekološke strane pri izgaranju i potrebno modificiranje nekih elemenata u motoru. Podaci korišteni u istraživanju dobiveni su kod mjerenja u laboratoriju za vozila. Rezultati su uspoređeni s dizel gorivom. Rezultati pokazuju da istraživana biogoriva pozitivno utječu na ispušne emisije motora ali uz veću potrošnju

Analýza změn výstupních parametrů motorů při spalování paliva E85

This Ph.D. thesis titled "Analysis of changes of engines output parameters at combustion of E85 fuel" describes the history and present use of bioethanol as a fuel for spark-ignition engines, as well as possibilities of its production and use in internal combustion engines. The comparison of the physico-chemical properties of the bioethanol and gasoline is also the part of the thesis. The experimental part is focused on the evaluation of engines basic parameters and emissions production. Engine and two vehicles were chosen to analyze the influence of E85 to change parameters mentioned above. Engines were originally designed to operate on gasoline. Hence, one of objectives of this thesis is to describe adjustment of the engine (originally designed for the combustion of gasoline) for operation on E85. The results of experimental measurements show that E85 fuel has a positive impact not only on the performance parameters of the engine, but also on the production of emissions. However, due to different properties of ethanol and gasoline is necessary increase amount of injected fuel. It leads to a negative impact on the fuel consumption of the engine

Flow behavior of petrol, bio-ethanol and their blends

The objective of this article deals with the flow behavior of bio-ethanol, conventional petrol and their blends (E15, E85). The temperature dependence density and kinematic viscosity of the liquids have been measured. The densitometer Densito 30PX with the scale for measuring fuels has been used to the measuring temperature dependence of the density of fuels and their blends. The rotary viscometer Anton Paar DV-3P has been used to the measuring temperature dependence of kinematic viscosity of fuels and their blends. For all samples has determined that the temperature has increased the density and kinematic viscosity of fuels and their blends has decreased. The range of temperature measurement has been from −10°C to 40°C. The mathematic models have been compiled (polynomial and exponential) according to the general shapes. The coefficients of determination R2 have achieved high values from 0.98 to 0.99 for temperature dependence of density of fuels and their blends and from 0.86 to 0.96 for temperature dependence of kinematic viscosity of fuels and their blends. The mathematical models could be used to the prediction flow behavior of petrol, bio-ethanol and their blends