Ágota Drégelyi-Kiss

Intensification of biogas production using pretreatment based on hydrodynamic cavitation.

The present work investigates the application of hydrodynamic cavitation (HC) for the pretreatment of wheat straw with an objective of enhancing the biogas production. The hydrodynamic cavitation reactor is based on a stator and rotor assembly. The effect of three different speeds of rotor (2300, 2500, 2700 rpm), wheat straw to water ratios (0.5%, 1% and 1.5% wt/wt) and also treatment times as 2, 4 and 6 min have been investigated in the work using the design of experiments (DOE) approach. It was observed that the methane yield of 31.8 ml was obtained with untreated wheat straw whereas 77.9 ml was obtained with HC pre-treated wheat straw confirming the favourable changes during the pre-treatment. The combined pre-treatment using KOH and HC gave maximum yield of biogas as 172.3 ml. Overall, it has been established that significant enhancement in the biogas production can be obtained due to the pretreatment using HC which can also be further intensified by combination with chemical treatment.

Experimental Design and Study of Shear Technology for Biomass Comminuting

To increase the security of energy supply, it is essential to search for utilization alternatives of renewable energy sources. The fermentation of organic material is more effective if the substrate is subjected to pre-treatment. In order to avoid toxic byproduct in the course of pre-treatment, a mechanical method was preferred. In this paper, the behavior of agricultural raw materials subjected to mechanical disintegration is examined. The pre-treatment of substrate was carried out with a comminuting machine which is normally used in industrial sewage fermenters in Hungary, but in agricultural biogas plants it has not been built in the technological process yet.

Measurement uncertainty and gauge capability of surface roughness measurements in the automotive industry: a case study

The calculation methods of the capability of measurement processes in the automotive industry differ from each other. There are three main calculation methods: MSA, VDA 5 and the international standard, ISO 22514–7. During this research our aim was to compare the capability calculation methods in a case study. Two types of automotive parts (ten pieces of each) are chosen to examine the behaviour of the manufacturing process and to measure the required characteristics of the measurement process being evaluated. The measurement uncertainty of the measuring process is calculated according to the VDA 5 and ISO 22514–7, and MSA guidelines. In this study the conformance of a measurement process in an automotive manufacturing process is determined, and the similarities and the differences between the methods used are shown.

Measurement Error on the Reconstruction Step in Case of Industrial Computed Tomograph

More recently, the industrial CT equipment is used not only for non-destructive analysis but to perform geometrical evaluations. The three dimensional, optical dimensional measurements made by CT are popular because the measurement time is much shorter than in case of traditional 3D measurement machines, furthermore the inner geometries can be determined by non-destructive manner. In this article the design and measurement plan of an aluminium test cube by industrial CT are described and the evaluation of the measurement data are presented.

The design, calibration and adaption of a dynamometer for fine turning

In cutting research, the determination of the spatial force system of cutting processes is extremely important. Therefore, the forces generated need to be measured with high precision. In this paper, the development of a special three-component dynamometer system is presented for the measurement of small forces (0100 N) in three directions during fine cutting, with a precision of 0.1 N. The designed dynamometer employs a piezo-electric cell and can easily be mounted on the tool post with only small modifications to the tool holder. The setup was calibrated for sensitivity, static load and range. By using error functions, the relative error in the measurement of force is kept below 1.5%.

Development of risk evaluation model of automotive supplier chains

The evaluation and selection of automotive suppliers is complex. It is necessary to create a unified system of essentials related to the safety risk of automotive supplier chain. In the course of the creation of the appropriate aspects the automotive supplier requirements, the economic viewpoints and safety requirements of ISO 28000 standard are taken into account. The evaluation model is based on a questionnaire filled by the participants of automotive supplier chain at all level. The developed mathematical model is suitable for the selection of a supplier company from the quality and risk points of view.

The Examination of the Cutting Capacity of Different Aluminium Alloys with Statistical Methods, Using Different Edge Material Non-Conventional (Wiper) Edge Geometry Diamond Tools

The aluminium alloys are used by the automotive, aerospace industries increasingly because of their numerous advantageous mechanical and chemical properties. Surface roughness measurements are essential in characterization of the features of a machined surface. The most widespread aluminium alloy used in cutting is the die-cast type, alloyed with silicon. Industries prefer using two types of such alloys, the so-called eutectic and hypereutectic alloys reinforced with silicon. In this article the cutting capacities of two die-cast aluminium alloys are examined. The cutting experiments were carried out with design of experiment – DOE (the so-called central composite design – CCD). In the course of the examination three factors were altered (cutting speed – vc, m/min; feed – f, mm; depth of cut – a, mm), and the main surface roughness parameters used in the industries were taken as output parameters. The parameters of the manufactured surface roughness and their deviation in case of different workpiece-materials, tool-materials and edge-materials were analysed with statistical methods. Besides minimizing surface roughness, another important criterion of the manufacturing system (machine – tools – chuck – workpiece) is its surface roughness maintaining capacity, which was analyzed with coefficient of variation (CV).