Zoltán Siménfalvi

Horizontal scraped surface heat exchanger — Experimental measurements and numerical analysis

This paper deal with the overall heat transfer process and confrontation of experimental measurements and their numerical solutions on simplified model, inside the horizontal scraped surface heat exchanger. The experimental measurements were done on two horizontal scraped surface heat exchangers connected in series. As a product was thermally treated water, heated by vapor in the first stage and cooled by cold water in the second stage. Applied mass flow of the product: m=250, 500, 750, 1000 kgh−1 and rotary velocity of the shaft, scraper blades: rpm=20, 30, (45), 60, 90 min−1. For numerical analyses the simplified model was used, with taking only the area between the heat transfer tube, and the shaft with an aim to compare the result to experimental measurements and validate the obtained overall heat exchange, as justify the simplification. As a results from experimental measurements were obtained the correlations for Nusselt number in a form of Nu=f(Re,Pr,ηf/ηw). Based on the confrontation of results, i...

Investigation of Pressure Rise in Automotive Airbags

Safety is a widely spread topic in engineering, from specific producing processes to everyday life. Innovation of passenger cars belongs to the frontline of industrial sector. Higher and higher performance motors, more streamlined vehicle dynamics, more reliable autonomous vehicles, and minor noise and vibration are the most expected developments what customers prefer. However, it is not allowed to forget automotive safety, which effectiveness prevents fatalities to drivers and passengers.

Utilisation of Various Hydro-Carbon-Based Wastes by Thermo-catalytic Conversion

The global need for energy and raw materials is constantly on the rise as mankind’s technology progresses. Due to more and more environmental load and fossil energy carriers exhausted, processes designed for thermo-catalytic conversion of various hydrocarbon-based wastes (plastics- and rubber waste, biomasses) and fuels with a low calorific value (lignite, brown coal) have come into focus in the last decades. The essence of these processes is that solid raw materials forming long carbon chains can be converted at medium-high temperatures (410–450 °C) by means of a special reactor system into more valuable hydrocarbon fractions of liquid and gas state such as petrol-, gas oil-, fuel gas-type products. We examined in our work, how low-quality rubber waste and/or brown coal, plastic waste raw materials can be converted into better quality products—of primarily liquid state. The problem raising a number of open points is a complicated optimisation issue as various heterogeneous components and their content in aggressive contaminants (sulphur, chlorine, nitrogen, oxygen, oxides, carbonates etc.) can largely affect decomposition kinetics thus the quality and quantity of hydrocarbon products formed so as well. This publication covers the system modelling techniques in detail that can be used as a foundation for the basis of mathematical modelling of high-complexity technical systems.

Investigation of Tyre Recycling Possibilities with Cracking Process

The field of vehicle tyres is a key pillar to the Vehicle Engineering BSc launched in September 2016 at the Faculty of Mechanical Engineering and Informatics of the University of Miskolc and the Tyre manufacturing postgraduate course in the technological specialisation on which work is in progress. Generating a yearly amount of several 100 millions of tyres as waste of the automotive industry is, almost 80% of them as passenger car tyres and 20% as truck tyres, whose management creates a huge load to bear on society. These days a relevant task of this field is to find a solution that is reducing environmental loads and sustainable to the solution. Vehicle tyres contain many organic and inorganic compounds: natural and artificial caoutchoucs (NR, SBR, BR, IIR, EPDM), silica, zinc oxide, sulphur, steel and artificial fibres, anti-ageing agents, carbon black etc. whose production requires a significant use of fossil energy carriers. There are several ways of recycling tyres lost their original function: incineration, recycling in its material (rubber-based pavements, roads, sporting grounds) or chemical conversion (energy carrier, chemical raw material), respectively. These days cracking in combined material flow embodies one of the main research directions of chemical conversion. The bottom line is that several raw materials are decomposed in parallel during catalyst-assisted thermal cracking: blends of different ratios of biomass, plastics, rubber tyre. This publication presents options of chemical conversion and its optimisable parameters. We investigated thermo-catalytic thermal cracking (cracking) of rubber and polystyrene waste producing thereby valuable petrol- and gas oil-type hydrocarbon products.