Dariusz Kardaś - Academia.edu (original) (raw)

Papers by Dariusz Kardaś

Wood Science and Technology

Pyrolysis is an oxygen-free process for the thermal decomposition of raw materials. The heat cond... more Pyrolysis is an oxygen-free process for the thermal decomposition of raw materials. The heat conduction and flow of pyrolysis products (i.e., the gas fraction and liquid vapour generated during pyrolysis) influence the process and products. In this work, the influence of the orientation of wooden particle fibres with respect to the direction of the heat source on the dynamics of the process was investigated, where there were two particle sizes oriented along or across the heat source. The novelty of this work lies in the use of a radiographic technique for analysing the influence of wooden fibres' orientation on the degradation process. The research showed that during pyrolysis, the mass loss rate in the particles with fibres oriented across the heat source and along the heat source was different. A similar tendency was characteristic for the drying process. The dynamics of pyrolysis of a single wood particle depends on many factors—particle size, process parameters, arrangement...

Journal of Mechanical Engineering

The thermal scheme of a power generating plant with a remote heat exchanger operating according t... more The thermal scheme of a power generating plant with a remote heat exchanger operating according to the Brayton cycle with energy recuperation is considered. It is assumed that the plant will work on non-certified (cheap) biofuel. It is shown that, in contrast to the usual Brayton cycle, in the cycle with energy recuperation, the greatest influence on the thermal efficiency is the heating temperature of the working medium and the internal efficiency of the main components of the plant, such as the compressor and the turbine. Also, in contrast to the usual Brayton cycle, a higher efficiency of the plant is achieved with smaller degrees of pressure reduction (increase) in the turbine (compressor). It was established that even at a relatively low temperature of the working medium heating (500 ºC), with high efficiency of the compressor and turbine, it is possible to achieve good characteristics of the power plant as a whole. At a temperature of up to 850 ºC, a thermal efficiency of 40% ...

Inżynieria i Aparatura Chemiczna, 2016

Inżynieria i Aparatura Chemiczna, 2018

European Biomass Conference and Exhibition Proceedings, 2016

Industrial gasification of biomass often face fouling caused by the formation of deposits. Foulin... more Industrial gasification of biomass often face fouling caused by the formation of deposits. Fouling can be particularly extensive when alternative biomass is gasified, with high concentrations of calcium, phosphorus, chlorine, sulphur and potassium. The good example of such awkward biomass is poultry feathers, which is successfully gasified in the robust 3.5 MWth fixed-bed updraft gasification plant in Olsztyn, Poland. The bottom ashes and fireside deposits, which are formed along the plant, were collected and analyzed by means of X-ray Fluorescence and X-ray Diffraction. The analysis revealed that bottom ash and deposits in gasifier consist more than 67 % of hydroxyapatite [Ca10(PO4)6(OH)2], the substitute of natural bones. In fact, different amount of hydroxyapatite is recognised in deposits collected from different apparatuses.

Archiwum Energetyki, 2012

Systems: Journal of Transdisciplinary Systems Science, 2006

Physicochemical Problems of Mineral Processing, Mar 19, 2017

The process of pyrolysis is investigated in this paper. The pyrolysis results of two samples: was... more The process of pyrolysis is investigated in this paper. The pyrolysis results of two samples: waste tyres and rubber at different heating rates (10, 20, 50 K/min), were compared. In other experiments the degradation of two pyrolysis products, char and oil was examined. The kinetic study using the thermogravimetry equipment (TG) was done, which allowed determination of the kinetic mechanism of the process. The elemental analysis of the samples was performed.

Drvna Industrija, 2017

Experiments on birch wood chips of a size < 20 mm have been conducted in a laboratory scale batch... more Experiments on birch wood chips of a size < 20 mm have been conducted in a laboratory scale batch pyrolysis reactor to study the effect of temperature on the pyrolysis product yields and the balance of elements in the products. The investigated variable was the pyrolysis temperature, which was equal to 300, 400 and 500°C in consecutive pyrolysis runs. Products were separated into fi ve fractions: gases, tar, water, char, and a low-boiling liquid fraction. The paper presents the mass share of each fraction as a function of temperature. The content of carbon, hydrogen and nitrogen was analysed in each fraction. The paper summarizes the weights of different fractions and the distribution of elements in each fraction. The gas fraction was analysed with the use of a gas chromatograph with thermal conductivity detector, while the liquid fraction was analysed in a gas chromatograph with mass detector. To analyse the content of C, H and N in tar and charcoal, an elemental analyser was used. The preformed study has revealed that the increase of the pyrolysis temperature leads to the increase of the amount of char and to the decrease of the amount of tars (heavy tars and low boiling tars). The amount of water in the pyrolysis products does not change as signifi cantly as the amount of tars, which is the result of constant amount of water obtained in the pyrolysis process. The amount of pyrogenic water increases with the increasing temperature of the process.

Archives of Thermodynamics, 2018

This study examines the pyrolysis of a single cylindrical wood particle using Particle Image Velo... more This study examines the pyrolysis of a single cylindrical wood particle using Particle Image Velocimetry (PIV). The pyrolysis was carried out in the ATR 01/600 pyrolysis reactor designed for this purpose. The experimental setup presented in this study is capable of effectively characterizing the intensity of pyrolysis based on velocity distribution in the vicinity of wood particles. The results of the gas velocity distribution indicate the formation of a gas cushion caused by the evaporation of moisture and devolatilization. Higher heating rates increase the intensity of degassing and the thickness of the gas cushion around the particle and may temporarily slow down the intensity of convective heat transfer to the interior of the particle.

Environmental Science and Pollution Research, Aug 16, 2023

Waste biomass, a renewable energy source, is inexpensive material that has great potential in sor... more Waste biomass, a renewable energy source, is inexpensive material that has great potential in sorption and electrochemical application. The selected waste materials (corncobs, coconut shells, walnuts, and pistachio husks) allow to close the production cycle and enable material recycling, which are important aspects in the hierarchy of waste management. The proposed methodology for production and activation of biochars can be used industrially due to highly porous structure, developed surface area, and sorption ability of the obtained activated carbons (AC). A significant increase (from 4 up to more than 10 times) in specific surface area (SSA) is observed for all samples after the CO 2 activation process (0.5 h at 800 °C) up to 725 m 2 g −1 for corncobs, 534.9 m 2 g −1 for pistachio husks, 523 m 2 g −1 for coconut shells, and 393 m 2 g −1 for walnut husks. The highest value of SSA is achieved for the AC derived from corncobs. This material is evaluated for use as an adsorbent, revealing 99% removal of Rhodamine B (dye/AC ratio of 0.0017) and 69% removal of chromium (dye/AC ratio of 0.0028). Based on the adsorption kinetics analysis, it is demonstrated that the Cr(VI) undergoes physical adsorption, while RhB undergoes chemisorption. In addition, corncob-derived AC exhibits superior electrochemical performance in 6 M KOH compared to the nonactivated biochar. A specific capacitance of 70 F g −1 at 5 A g −1 is achieved, along with outstanding rate capability (45 F g −1 at 50 A g −1) and cycling stability (94% at 10 A g −1 after 10,000 cycles). In contrast, the nonactivated sample shows only 34 F g −1 at 5 A g −1 and 13 F g −1 at 50 A g −1 , with a stability of 91.4%.

The co-generative micro-power plant with the HFE7100 applied as a working medium was designed and... more The co-generative micro-power plant with the HFE7100 applied as a working medium was designed and built for experimental investigations. Special attention is paid to a micro-turbine which was built and tested in two variants: a radial turbine and an axial turbine. A concept of a radial turbine with 2 centripetal and 2 centrifugal stages is shown. This prototype was equipped with an aerostatic gas bearing and, alternatively, with a foil bearing. An axial multi-stage turbine with partial admission of all the stages is described in detail and the results of experimental investigations and numerical calculations are presented, followed by a discussion and conclusions. The results showed that, for example, remarkable flow separation zones appeared in the nozzle flow channels placed at the edge of the admission segments. The modifications of these channels reduced the undesirable effect. All the stages were equipped with movable blade shields for reducing windage losses. The effect of the...

Transactions of the Institute of Fluid-Flow Machinery, 2013

The aim of the paper is to present the results of experimental research conducted on helical coil... more The aim of the paper is to present the results of experimental research conducted on helical coil biomass boiler with oil as a heating fluid, which is a central unit of co generative micro powerplant designed and tested at the Institute of Fluid-Flow Machinery in Gdańsk. Experimental data has been used to work out characteristics of the device in terms of power, efficiency and oil parameters for moderate/high excess air numbers and fuel flow rates. Furthermore, during the research the authors came across various obstacles, which can be easily eliminated in the future prototypes by applying presented changes in construction.

Proceeding of THMT-12. Proceedings of the Seventh International Symposium On Turbulence, Heat and Mass Transfer Palermo, Italy, 24-27 September, 2012, 2012