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Synthesis gases produced from municipal waste or plastic waste pose a great alternative source of energy, as they are not only reducing dependency on the fossil fuels, but also diversify energy sector and reduce the amount of a landfilled waste. This is directly related to the recent initiatives and legislation related to the greening of transport. The presented contribution focuses on the influence of six selected synthesis gases on the internal parameters of an internal combustion engine intended for cogeneration. The investigated gases fall into the category of medium-energy gases (8 – 14 MJ.kg−1). The experimental measurements have shown that mainly the proportion of hydrogen in the mixture has an effect on shortening the burning time and also on the maximum rate of pressure increase. A higher proportion of CO and H2 increased the maximum combustion pressure with slightly reduced power. The concentration of CH4 directly affected the volumetric value of the heating value of the mixture with a subsequent direct effect on the IMEP or engine torque. The engine operating at full load at speed of 1500 min−1, when running on the selected mixtures in comparison with the operation on natural gas, decreased its engine torque in the range between 13 and 20% and increased its hourly fuel consumption from 2.31 kg.h−1 for natural gas to the span of 7.90 - 12.30 kg.h−1 for measured gases. During the measurement of the control characteristic all investigated synthesis gases have developed an abnormal (detonation) combustion near the optimum pre-ignition angle.

Based on the flow modeling and operational experience of the previous cylindrical loop reactor, we designed a sheet reactor combined with a loop reactor. The design with a cylindrical cross-section was applied to an equivalent cross-section (sheet) of several squares arranged next to each other. In accordance with the sedimentation processes experienced in the outlet branch, we created an algae trap, thereby reducing the flow to the level necessary for sedimentation. With this, I would like to achieve the already experienced, nearly 10-fold increase in algae concentration compared to the one in the mainstream.

The paper presents a strength analysis of a pressed joint of two conical pipes with the aim of finding out whether this method of connection is suitable for telecommunication masts. In this paper, a solution using an engineering approach and a finite element method (FEM) numerical analysis for transversal direction will be compared.

In the scope of the green energy and climatic changes waste poses as a great resource as an alternative fuel or source for their production. This helps to decrease the need for fossil resources, as well as diversify energy production. This kind of waste utilization and mitigation therefore directly fits into latest legislation and green initiatives. This paper focuses on the influence of five synthesis gases with relatively high heating values on the internal parameters of the internal combustion engine intended for cogeneration. Measurements show that proportion of the hydrogen in the mixture has indirect influence on the combustion duration and also maximal pressure rise rate. Interestingly hydrogen proportion in fuel showed no direct influence on the maximal in-cylinder pressure. Higher CO to CH4 ratio reduced burn time and increased maximal combustion pressure with slightly decreased performance. Concentration of CH4 directly influenced volumetric LHV value of the mixture with subsequent influence on the IMEP and engine effective torque. Generally, operation of the engine at full load at 1500 min−1 on chosen mixtures compared to the runs on methane showed decrease of engine torque output of up to 13.4% and increase of the hourly fuel consumption from 1.56 for pure methane to maximally 3.87 kg.h−1 for measured gases. Lastly, for one of the fuels erratic engine operation was observed.

For the purpose of efficient algae cultivation, the Photo Bio-Reactor (PBR) must be designed according to the needs of the algae to be cultivated. We performed our experiment with a loop reactor with a total volume of 14 liters. Among other things, the mixing of the gas and liquid phases, the value and change of the light intensity reaching the algae, and the degree of algae deposition on the walls of the equipment depend on the flow caused by the bubble column in the equipment. Using the ANSYS FLUENT simulation environment, we optimized the efficiency of the gas intake that determines the flow.

This paper presents a stress analysis of a pressed joint of two conical pipes with the aim to find out whether this kind of connection is suitable for telecommunication masts. The analysis can be considered a complex spatial problem of a thin-walled shell, where the local bending stress influence might be dominant. In this paper a solution using engineering approach and numerical analysis with finite element method (FEM) will be compared.

The aim of the article is to point out the sealing efficiency of the two-language seal of the water pump bearing when radially deflecting the shaft within radial clearance. In order to obtain a radial displacement of the shaft at a location under a two-language seal, dynamic bearing simulation was performed using the MSC Adams program. The largest radial deviation of the shaft was applied in final seal analysis where the contact pressure changes on the individual tongues of the seal were recorded.

The article deals with the contribution of Dr.h.c. mult. prof. Ing. František Trebuňa, CSc to the field of engineering. Born in 1947, he studied and subsequently remained at the Faculty of Mechanical Engineering, Technical University of Košice since 1965. Under his leadership 25 dissertation theses were defended in the study programs Applied mechanics, Mechatronics and Forensic engineering. He is author to 14 monographs, 16 textbooks, 5 other books, 12 university textbooks and more than 350 original scientific papers published in domestic and foreign journals and conference proceedings. Professor Trebuňa is currently the dean at the faculty and is known as a gifted educator.

Welding is a complex technological process in which local heating takes place up to the melting point of the connecting and the additional material. Phase and crystallization processes are a strong non-linear function of the cooling rate. This non-linear function multiplies the complexity of the numerical simulation and optimization of the welding process. Lately, optimization with genetic algorithm has become the trend to optimize systems that behave in a non-linear manner and contain a number of local extremes. Genetic algorithm is therefore a method by which we seek an absolute extreme. It is a method which seeks a solution to near absolute extreme. In this paper the use of the genetic algorithm for welding process optimization is described.

The article is devoted to bearing analysis, which has a specific shape. The outer ring is the body directly and the inner ring is the case. To determine optimal radial clearance or overlap are used the thermal / structural analysis. The article is logically divided into two parts. In the first analysis, was monitored the impact of the press-fit of the case into the body. In the second analysis, there are presented attained results in graphical outputs of displacements in the orbits at different operating temperatures. At the end of the article were evaluated and researched individual effects on bearing deformation.

This article is devoted to the comparison of the influence of the piezoelectric matrix properties on the magnitude of the resulting charge when a thin piezoelectric membrane of circular cross section, made from aluminium gallium nitride (Al-GaN), is loaded. The size of change of the electric charge was determined by the numerical analysis and the by the change of the properties of the piezoelectric matrix. The matrix constants were obtained from various sources introduced in world databases.

The present paper deals with the calculation of stresses on the pipeline system embedded on a flexible substrate which is burdened by a landslide. As well as taking into account the probability of the influences acting on the pipe as wall thickness, and others.

This article deals with a simple planar and statically determinate pin-connected truss. It demonstrates the processes and methods of derivations and solutions according to 1st and 2nd order theories. The article applies linear and nonlinear approaches and their simplifications via a Maclaurin series. Programming connected with the stochastic Simulation-Based Reliability Method (i.e. the direct Monte Carlo approach) is used to conduct a probabilistic reliability assessment (i.e. a calculation of the probability that plastic deformation will occur in members of the truss).

Friction Stir Welding (FSW) is one of the most effective solid state joining processes and has numerous potential applications in many industries. The simulation process can provide the evolution of physicals quantities such as temperature, metallurgical phase proportions, stress and strain which can be easily measured during welding. The numerical modelling requires the modelling of the complex interaction between thermal, metallurgical and mechanical phenomena. The aim of this paper is to describe the thermal-fluid simulation of FSW using the finite element method. In the theoretical part of paper heating is provided by the material flow and contact condition between the tool and the welded material. Thermal-mechanical results from the numerical simulation using SYSWELD are also presented for aluminium alloy.

In this paper an alternative J2 material model with isotropic hardening for finite-strain elastoplastic analyses is presented. The model is based on a new nonlinear continuum mechanical theory of finite deformations of elastoplastic media which allows us to describe the plastic flow in terms of various instances of the yield surface and corresponding stress measures in the initial and current configurations of the body. The approach also allows us to develop thermodynamically consistent material models in every respect. Consequently, the models not only do comply with the principles of material modelling, but also use constitutive equations, evolution equations and even ‘normality rules’ during return mapping which can be expressed in terms of power conjugate stress and strain measures or their objective rates. Therefore, such models and the results of the analyses employing them no longer depend on the description and the particularities of the material model formulation. Here we briefly present an improved version of our former material model capable of modelling ductile-to brittle failure mode transition and demonstrate the model in a numerical example using a fully coupled thermal-structural analysis.

This article is devoted to the solution of the thermal field of a particle for Bi > 0 with an ideal spherical shape and the behavior of the temperature in the fluid phase with countercurrent contact. After establishing the underlying simplified assumptions and defining the initial and boundary conditions in the form of dimensionless criteria, a mathematical formulation of the problem is transformed into a suitable and solvable form. The formulation is then used in the analysis. [ABSTRACT FROM AUTHOR]