Michael Harasek

TU Wien | TU Wien · Institute of Chemical Environmental and Bioscience Engineering

Alternative reducing agents (ARAs) can be an ecologically attractive substitution for pulverized coal in the blast furnace raceway zone. However, the grinding behavior of ARAs, e.g., biomass, can be different from coal and yield larger particle sizes. It has to be evaluated if larger, thermally thick, particles show a suitable thermochemical conver...

The thermochemical conversion of alternative reducing agents (ARAs), such as pulverized coal, in the blast furnace raceway zone is a complex and hard to examine process due to the harsh conditions. Real-world experiments provide non-ideal conversion conditions, e.g., inhomogeneous temperature and velocity and concentration fields. Ignoring these in...

The injection of auxiliary reducing agents (ARAs) into the raceway zone of a blast furnace can contribute to a reduction of the ironmaking process's environmental impact and costs (partial replacement of metallurgical coke). Detailed knowledge about the conversion behavior of ARAs is necessary to increase the efficiency of their injection. A novel...

This study aims to integrate a novel bio-purification process employing an engineered E. coli strain in the downstream processing of lactic acid (LA) fermentation broths from low-cost renewable biological feedstocks. Fermentation broth of candy waste and digestate mixture was used as a real biological feedstock. An engineered E. coli strain that se...

Background A potential alternative to lactic acid production through sugar fermentation is its recovery from grass silage leachate. The separation and purification of lactic acid from fermentation broths remain a key issue, as it amounts to up to 80% of its industrial production cost. In this study, a genetically engineered E. coli strain (A1:ldhA)...

Background: A potential alternative to lactic acid production through sugar fermentation is its recovery from grass silage leachate. The separation and purification of lactic acid from fermentation broths remains a key issue, as it amounts to up to 80% of its industrial production cost. In this study, a genetically engineered E. coli strain (A1:ldh...

This paper highlights the importance of bioreactors in the bioeconomy, focusing on the role of mechanical mixing in promoting optimal conditions for microorganism growth and productivity. Computational fluid dynamics (CFD) simulations are increasingly used in bioreactor design to predict fluid dynamics and mixing characteristics. This study utilize...

This research proposes a low-cost solution for the abatement of GHG emissions generated by untreated animal manure. Retrofitting earth-lined slurry tanks into covered lagoons could help the Irish Agricultural sector meet the Paris Agreement's Goals.

Background : Minimising internal pressure drop in pipes is crucial for energy efficiency of fluid flow applications. Numerous computational optimisation tools that are capable of modifying flow geometries to reduce the pressure drop have been developed. Among these is a comparably simple heuristic optimisation algorithm which mimics erosion and sed...

Anaerobic Digestion (AD) has been gaining popularity in the last decades for the production of biogas from organic waste, agricultural waste, and energy crops. Biogas is a mixture of approximately 70 % methane, 29 % carbon dioxide, and 1 % other gases. Biogas plants produce electrical and thermal energy by burning the biogas in combined heat and po...

A higher level of atomization of the fuel leads to a more homogeneous mixture with the air in internal combustion engines, whether they are equipped with direct injection or port fuel injected systems. The further break-up of the atomized fuel drops by the interaction of two fuel sprays is described in this paper. In the present research, a simulat...

Hydrogen production via water electrolysis is one of the most sustainable and efficient pathways to global decarbonization. It is rapidly scaling up, and with this, the resource consumption. Membrane-based seawater desalination is a low-impact cost and well-established technology. However, different factors must be considered: Water loss and waste...

An entire utilization of alternative reducing agents inside the raceway zone is favorable to increase the coke replacement ratio in blast furnaces and utilize waste products in the ironmaking process. The extreme conditions prohibit measurements, but computational fluid dynamics incorporating validated models can help to understand the processes oc...

Gas and oil separation plants are the first main step in the production of hydrocarbon products. Depending on the properties of the recovered components from the well heads, and the physical properties in the underground rock reservoir, the plant design can vary in different ways. In mature oil and gas fields, secondary recovery methods are often u...

Reasonable iron ore reduction and melting prediction are critical issues for blast furnace modeling. The particle number required for full-scale blast furnace simulations exceeds the current capabilities of discrete element method (DEM) approaches. Continuum or Euler-based approaches can handle industry-scale equipment at reduced accuracy. This wor...

Alternative reducing agents (ARAs) injected into the raceway zone of the blast furnace have diameters in the range of tens to thousands of micrometers. Larger ARA particles can develop significant internal temperature and species concentration gradients. These gradients determine the thermochemical ARA conversion characteristics. To capture these e...

Injecting auxiliary reducing agents (ARAs) in the raceway zone of a blast furnace increases the efficiency and reduces CO2 emissions in case using bio-based sources. Reliable conversion rates are crucial to identify new ARAs or their mixtures and to optimize the ARA injection process, but they are hardly available in literature. The harsh reaction...

The safe, affordable, and eco-friendly storage of gases is a pressing environmental concern worldwide. Porous carbon, as a widely utilized adsorbent with a broad pore size distribution spanning from small micropores to large macropores, is unsuitable for the selective adsorption of gases with very small molecular size, such as hydrogen. Although th...

In this study, Computational Fluid Dynamics (CFD) is utilized to compare the hydrodynamics of internal loop air lift bioreactors with three different internal configurations. This CFD study compares how splitting the draft tube into multiple stages affects the hydrodynamics of an airlift bioreactor. An in-house Lagrangian particles coupling utility...

In this study, Computational Fluid Dynamics (CFD) is utilized to compare the hydrodynamics of internal loop air lift bioreactors with three different internal configurations. This CFD study compares how splitting the draft tube into multiple stages affects the hydrodynamics of an airlift bioreactor. An in-house Lagrangian particles coupling utility...

The separation of immiscible liquids is critical in many industrial processes, such as water treatment, different extraction processes, the petroleum industry, food production, and medicine. This work provides an overview of present research on the separation of liquid mixtures. A brief summary of the thermodynamic basis is provided, covering phase...

Biorefinery systems play a critical role in the transition towards a sustainable bioeconomy, and bioreactors are a key component in these systems. While mechanically stirred reactors have been extensively studied, there is a lack of research on pneumatically driven systems like airlift reactors (ALRs). This study aims to address this gap by examini...

The paper investigates applicability of two mathematical models developed by the authors for calculating the process of long-term impregnation of coal samples. A distinctive feature of the studied samples is low porosity. Considered models are based on single- and three-channel representation of the internal structure of a porous medium. These mode...

The article presents a study on the suitability of silica pillared clay (SPC) encapsulated with biopolymers, such as alginate, chitosan, or a combination of both, for the adsorption of Ni(II) from aqueous solutions. In the current age of stringent environmental regulations, there is an urgent requirement to identify novel sorbents that can be readi...

The use of lignin, an abundant phenolic bio-polymer, allows us to transform our fossil-based economy into a sustainable and bio-based economy. The transformation of bulk lignin into colloidal lignin particles (CLPs) with well-defined surface chemistry and morphology is a possible way to cope with the heterogeneity of lignin and use it for material...

Lignin, a main component of plants, is produced in large quantities as a by-product of the pulp and papermaking industry. The abundance of this organic polymer makes it an excellent candidate for developing renewable materials such as lignin-based biocomposites. The mechanical properties of lignin, as well as the dependence on the extraction proces...

Around 50% of sawn wood remains as a by-product during the processing into timber. A large part of these by-products consists of sawdust, which still contains a lot of intact fibers and would have great potential to be used for biocomposite materials. This study investigates the influence of different pretreatments on spruce sawdust in a two-step p...

The main production route for steel in Europe is still via the blast furnace. Computational fluid dynamics (CFD) can be used to analyze the process virtually and thus improve its performance. Different reducing agents can be used to (partially) substitute the coke and consequently reduce overall emissions. To analyze different reducing agents effec...

It is expected that European biogas production will double by 2030 and quadruple by 2050. There are currently more than 18,943 biogas plants operating in Europe. With the emergence of biogas upgrading technologies, biogas is upgraded into biomethane with carbon dioxide as a byproduct. A common practice in biomethane plants is to release carbon diox...

Starch hydrolysates have strict quality demands of production where low content of impurities is required. The quality of the product depends on the raw material, the suitability of clarification and the evaporation process of juices. The manufacture of starch products plays an essential role in numerous applications in widely different industries,...

Gas permeation and pervaporation are technologies that emerged several decades ago. Even though they have discovered increasing popularity for industrial separation processes, they are not represented equally within process simulation tools except for commercial systems. The availability of such a numerical solution shall be extended due to the des...

Membrane oxygenators are devices that benefit from automatic control. This is especially true for implantable membrane oxygenators—a class of wearable rehabilitation devices that show high potential for fast recovery after lung injury. We present a performance comparison for reference tracking of carbon dioxide partial pressure between three contro...

Hydrogen storage in a depleted gas field is a promising solution to the seasonal storage of renewable energy, a key question in Europe’s green transition. The gas composition and pressure in the month-long storage and recovery phase can vary substantially; meanwhile, the recovered H2 has to be pure, especially for fuel cell applications. Pressure s...

Cavitation is the major cause of the effective flow area reduction in fuel nozzles, together with mechanical damage, which leads to an increase of pressure losses. This paper describes the effect of different geometries along the fuel nozzle holes simulated with OpenFOAM® to control the cavitation and shape of the fuel jet. Previous work has only f...

Food production is the main challenge for developing arid regions due to the restricted access to fresh water. This study combines the environmental know-how of two coastal desert regions on the American continent with similar geographical characteristics to propose a general model for a circular economy in stressed environmental conditions. The At...

With the current shift from a fossil-based to a biomass-based economy, the study of biorefineries and their main components has gained significant importance. The main components of biorefineries include bioreactors. For many systems, the improvement of mass transfer in and between phases through mixing is the key success factor. So far, many studi...

Air humidification systems are in demand in many industrial and municipal sectors. Bubble columns are one of the most common forms of laboratory-scale humidifiers. Many operating parameters affect the performance of these systems, such as bubbler geometry, gas flow rate, temperature, the water level in the bubbler, and nozzle type. Since considerin...

In the search for new adsorbents for wastewater treatment, a modified clay-based adsorbent for the adsorption of Ni(II) was proposed in the present study. Silica pillared clays (SPCs) are adsorbents with high specific surface area and thermal stability, which have not been thoroughly investigated for their metal adsorption capacity. SPC was prepare...

The decolourization during the production of starch hydrolysates involves removing impurities to obtain a brilliant, light-coloured, transparent syrup. However, conventional processes in the industry result in low yield and quality, wasting energy and high-value chemicals. Therefore, starch hydrolysate production requires new separation techniques,...

To increase the efficiency of blast furnaces (BF), auxiliary reducing agents (ARAs) are injected into the raceway zone. Reliable conversion rates are essential to identify suitable reducing agents and to optimize their usage. The harsh reaction conditions in the raceway zone of a BF with temperatures above 2,000 K, heating rates up to 10 6 K/s and...

Due to its ability to recapitulate key pathological processes in vitro, midbrain organoid technology has significantly advanced the modeling of Parkinson's disease over the last few years. However, some limitations such as insufficient tissue differentiation and maturation, deficient nutrient supply, and low analytical accessibility persist, altoge...

Membrane processes can be integrated with fermentation for the selective separation of the products from the fermentation broth. Sterilization with saturated steam under pressure is the most widely used method; however, data concerning heat sterilization applicability to polymeric ultrafiltration (UF) membranes are scarcely available. In this study...

Titanium-pillared clay (Ti-PILC), as one of the most suitable types of porous adsorbents/(photo)catalysts, was prepared from a local type of Iranian clay and titanium isopropoxide. The production process was optimized by changing three operating parameters, including the clay suspension concentration (in the range of 0.5-10% w/v), the H+/Ti ratio (...

Biorefineries offer potential pathways for producing food, feed, organic chemicals, fuels, polymers, and electricity from biomass with complex processing technologies. Among these complex processing technologies, the design and analysis of bioreactors are crucial to the successful operation of biological processes. The improvement of mass transfer...

The motion of non-spherical particles with sharp edges, as they are commonly involved in practice, was characterized by residence time distribution (RTD) measurement in a continuous drum. Particles with two sizes, 6 and 10 mm, and two densities, 750 and 2085 kg/m3, were used in the experiments. The effects of rotation speed (3–11 rpm), incline angl...

To increase the coke-replacement ratio in blast furnaces an efficient utilization of alternative reducing agents inside the raceway zone is necessary. The extreme conditions prohibit measurements, but computational fluid dynamics can help to predict the processes directly in the raceway zone. Validated models to correctly predict the conditions are...

The current collapse of Earth's system is anthropogenic. Therefore, the way our societies function is put into question. A response to such collapse requires transformative societal changes. The transition to a bioeconomy and the deployment of biorefineries are expected to address these global issues, providing large scale and deep changes. In this...

The present work studied an air-to-air exchanger comprising a flat plate module with a diagonal channel and a counterflow configuration for the air streams. The objective of this study was to remove moisture and sensible heat from an exhaust air stream by indirect contact with another air stream. The temperature and flow rate of the exhaust air was...

Food production in desertic regions is a challenge due to the restricted access to freshwater. A major challenge for the development of desertic coastal regions (CR) is thus to minimize the cost of water desalinization and maximize its utilization for agriculture, industrial, commercial and residential use. The goal of this study is to define a lo...

Clay bricks have been used as a construction material by humans since thousands of years. Modern brick making however is challenged by the still energy-intensive production, coming together with considerable amounts of greenhouse gas emissions and consequently climate impact. Therefore, the physicochemical fundamentals of the brick firing process s...

Lactic acid (LA) is an organic acid produced by fermentation or chemical synthesis. It plays a crucial role in the pharmaceutical, food and plastic industries. In the fermentation of, for example, grass silage, LA and different compounds are produced. To purify lactic acid, researchers have tried to investigate membrane technology to achieve a high...

Electrodialysis (ED) is a promising technology suitable for nutrient recovery from a wide variety of liquid waste streams. For optimal operating conditions, the limiting current density (LCD) has to be determined separately for each treated feed and ED equipment. LCD is most frequently assessed in the NaCl solutions. In this paper, five graphical m...

Heat transfer to particles is a key aspect of thermo-chemical conversion of pulverized fuels. These fuels tend to agglomerate in some areas of turbulent flow and to form particle clusters. Heat transfer and drag of such clusters are significantly different from single-particle approximations commonly used in Euler–Lagrange models. This fact prompte...

Membrane-based gas-to-gas enthalpy exchangers have a significant position in energy recovery systems, especially in building ventilation. Membrane-based heat exchangers are similar in design to sensible heat exchangers, with a semi-permeable membrane instead of solid interface plates to recover sensible heat and moisture simultaneously. In the pres...

Heat transfer is a crucial aspect of thermochemical conversion of pulverized fuels. Over-predicting the heat transfer during heat-up leads to under-estimation of the ignition time, while under-predicting the heat loss during the char conversion leads to an over-estimation of the burnout rates. This effect is relevant for dense particle jets injecte...

CFD optimisation and analysis of existing AD and Biorefineries Report is part of the European Project A Disruptive Innovative Cooperative Entrepreneurial (DICE) education, training and skills development programme rolling out the next generation of Agri Biorefinery and Valorisation Bioeconomy leaders (AGREFINE). The aim of this report is to provide...

In this work, we derive a model for the anisotropic effective thermal conductivity of bricks based on the unit cell model approach. The presented model considers conduction and surface-to-surface radiation in the brick. Four different radiation models are presented, compared, and validated using fully resolved computational fluid dynamics simulatio...

Multi‑phase reactive flows are an immanent aspect of chemical engineering applications, e.g. solid fuel conversion, thermo‑chemical energy storage, or heterogeneous catalysis. In recent years, applying computational methods for process optimization or intensification has become more popular. Computational Fluid Dynamics (CFD) provides a spatially r...

Slow pyrolysis of biomass is commonly performed in rotary kilns. The effect of the particle residence time distribution on biomass conversion is often neglected when numerically modeling such systems. But this effect might be significant under certain conditions. The data presented here are results of numerical simulation of the biomass pyrolysis i...

Detailed particle models can be used to model the thermo-chemical conversion of char and coke under metallurgical conditions, e.g., blast furnaces or smelting gasifiers. The simulation results of such models can reveal potential measures for efficiency increase. In this work, we investigate how diffusion models influence the modelling of the thermo...

Injecting pulverized coal into the raceway zone of blast furnaces is a state of the art process to minimize the furnace's ecologic and economic footprint. Modelling the thermo-chemical conversion of pulverized coal in the raceway zone is commonly used to investigate its effect on the blast furnace process or to optimize the coal injection process....

Particle clusters form in the turbulent flow of boilers and furnaces when injecting pulverized coal. We study the difference in conversion behavior between a pulverized coal cluster and a single char particle. The simulations are done using a detailed particle model in OpenFOAM R. The detailed particle model is capable of spatially resolving char p...

Gas-solid reactions often play key roles in chemical engineering applications. To understand and design processes featuring such heterogeneous reactions, kinetic models are crucial. One way to identify kinetic models is via thermal analysis experiments. Even if those experiments are carried out meticulously, there will be some deviation between nom...

Background: Ethyl lactate is an environmentally benign solvent, which could substitute petrol-based volatile organic compounds (VOCs) in many applications if production costs are reduced. It is usually produced by the esterification of lactic acid with ethanol – two important chemical building blocks of biorefineries that are available at industria...

A series of porous clay samples prepared at different pretreatment temperatures have been tested in a diffusion chamber. Diffusivity and permeability were examined in a temperature range from ambient to 900 °C. Gaseous mixtures of O2, CO2, and N2 have been applied, as these species are the relevant gases in the context of clay brick firing and simi...

Blood pumps are becoming increasingly important for medical devices. They are used to assist and control the blood flow and blood pressure in the patient’s body. To accurately control blood pumps, information about important hydrodynamic parameters such as blood flow rate, pressure difference and viscosity is needed. These parameters are difficult...

Owing to its computational efficiency, the two-fluid model is widely used in computational fluid dynamics (CFD) to describe gas-solid flows in large-scale industrial processes. The motion of the solid phase is commonly modeled by the kinetic theory of granular flow (KTGF). The main conceptual difference between the two commonly used KTGF closure re...

Background: Ethyl lactate is an environmentally benign solvent, which could substitute petrol-based volatile organic compounds (VOCs) in many applications if production costs are reduced. It is usually produced by the esterification of lactic acid with ethanol – two important chemical building blocks of biorefineries that are available at industria...

The formation of the raceway zone in the blast furnace depends on the momentum introduced by the hot blast and other alternative reducing agents and the coke consumption due to thermo-chemical conversion processes. While the influence of the introduced momentum on the raceway size has been evaluated extensively in literature, the sensitivity to the...

In connection to present energy demand and waste management crisis in Pakistan, refuse-derived fuel (RDF) is gaining importance as a potential co-fuel for existing coal fired power plants. This research focuses on the co-combustion of low-quality local coal with RDF as a mean to reduce environmental issues in terms of waste management strategy. The...

As a part of our research in the field of thermochemical energy storage, this study aims to investigate the potential of three fly ash samples derived from the fluidized bed reactors of three different pulp and paper plants in Austria for their use as thermochemical energy (TCES) and CO2 storage materials. The selected samples were analyzed by diff...

Animal blood is used in mock circulations or in forensic bloodstain pattern analysis. Blood viscosity is important in these settings as it determines the driving pressure through biomedical devices and the shape of the bloodstain. However, animal blood can never exactly mimic human blood due to erythrocyte properties differing among species. This r...

Extracorporeal membrane oxygenators are essential medical devices for the treatment of patients with respiratory failure. A promising approach to improve oxygenator performance is the use of microstructured hollow fiber membranes that increase the available gas exchange surface area. However, by altering the traditional circular fiber shape, the ri...

CO2 removal via membrane oxygenators has become an important and reliable clinical technique. Nevertheless, oxygenators must be further optimized to increase CO2 removal performance and to reduce severe side effects. Here, in vitro tests with water can significantly reduce costs and effort during development. However, they must be able to reasonabl...

opiTemp aims to become a low budget solution for the spatial temperature evaluation. A large-scale deployment of spatially resolved temperature measurements has huge potential for process optimization and control. Plank's and Wien's displacement law are utilized to determine temperatures from intensities ratios of the RGB color channels. The recons...

The Eddy Dissipation Concept is often applied to couple turbulence and chemistry in computational fluid dynamics, because it can be coupled with any chemical mechanism. The solution of a system of ordinary differential equations is required to calculate the mass fraction changes. We present an approach to substitute the ODE-Solver by multiple artif...

After decades of simply being referred to as the body's sewage system, the lymphatic system has recently been recognized as a key player in numerous physiological and pathological processes. As an essential site of immune cell interactions, the lymphatic system is a potential target for next-generation drug delivery approaches in treatments for can...

Rotary kilns are widely used in industry to perform several different operations. When numerically modeling such systems, a common simplification is to neglect the residence time distribution of particles. The present study numerically investigates the influence of particle residence time distribution on the pyrolysis of biomass in a co-current hea...

This document contains the executive summary, introduction, conclusion, and chapter three of the State-of-the-art Report on Anaerobic Digestion and Biorefinery Systems Level Design, to consult the other chapters visit the Community Research and Development Information Service (CORDIS) platform. The executive summary, introduction, and conclusion w...

Physiological‐relevant in vitro tissue models with their promise of better predictability have the potential to improve drug screening outcomes in preclinical studies. Despite the advances of spheroid models in pharmaceutical screening applications, variations in spheroid size and consequential altered cell responses often lead to nonreproducible a...