Frank Behrendt

• Dipl.-Chem., Dr. rer. nat. habil.
• Professor (Full) at Technische Universität Berlin

Piled smouldering has great potential for treatment and utilization of biomass wastes. However, its unsteady-state nature limits its industrial utilization, as well as treatment of smoke. This article addresses this issue by proposing the sequential operation of numerous smouldering chambers to realize steady- or quasi-steady-state piled smoulderin...

Content Tractor Drive Trains An Analysis of Mixed Hydraulic and Electric Configurations for the Actuation of Tractor Auxiliary and Implement Functions to Reduce Power Consumption 1 The development of a reference working cycles for agricultural tractors 15 Performance optimization of CVT standard tractors in front loading application 21 Numerical si...

A char cone, whose shape is similar to Bunsen flame and varies with oxidation conditions, was found in steady smoldering of biomass rods. In this short communication, characteristics of this char cone in natural downward smoldering of char rods with different diameters (2 – 7 mm) and ash contents (30–46%) were investigated via measuring propagation...

The objective of this paper is to measure the vapor pressure of potassium chloride (KCl) in its mixture with potassium sulfate (K2SO4). Evaporation behavior of pure salts of KCl, K2SO4, and their mixtures at different molar fractions were examined using a simultaneous thermogravimetric analyzer (STA) at different temperatures with a pair of crucibl...

The energy transition process fosters decentralized renewable energy generation and is characterized by an increased effort to achieve energy autarky. In this context, residential-size, photovoltaic-based multi-carrier energy systems using hydrogen as seasonal storage are analyzed as a possible solution to gain energy autarky. A high temporal (15 m...

Electrification of a waste collection fleet as part of vehicle-to-grid can be used in a grid- beneficial way, which in turn can increase the economy of these vehicles. In this study the system and grid integration of fully battery-electric waste collection vehicles (eWCV) is examined. The possibility to shave power peaks of a lightweight packaging...

In order to assess the possibility of silica production via smoldering of moist rice husk, experiments of washed (moist) rice husk (7 kg with moisture content of 51%) in a newly designed smoldering apparatus was performed. The temperature inside the fuel bed during smoldering was recorded, and characteristics of ash were analyzed. Results showed th...

In utilization of biomass, kinetic data for char oxidation based on surface area are essential for prediction of burnout time of biomass, which is an important parameter in reactor design. In this study, experiments with maize stover char were performed in a simultaneous thermal analyzer (STA) to obtain these kinetic data. Mass loss and heat effect...

In order to deepen the understanding of the thermochemical behavior of reactive inorganics, which play an important role in slagging and fouling during combustion of agro-stalks, the oxidation behavior of the water-soluble fraction of corn stover, wheat straw and rice straw was examined using a simultaneous thermogravimetric analyzer. The oxidation...

3D pore-scale simulations of the flow and thermal non-equilibrium for low-velocity filtration combustion are numerically performed in randomly packed bed of 2282 pellets with a diameter of 5.6 mm. A 1D volume-averaged simulation is also conducted for comparison. The root-mean-square (RMS) of variables is used to quantitatively study the non-equilib...

Solar Home Systems are a promising solution to enable access to affordable, reliable, sustainable, and modern energy for non-electrified areas, especially in the Global South. In this study, the influence of the charge controller technologies Maximum Point Tracker (MPPT) and Pulse Width Modulation (PWM) on the optimal system design and system perfo...

In this work, the experimentally discovered effect of flexophotovoltaics (FFV) in silicon p-n structures under the influence of local mechanical stress on the front surface is theoretically justified for the first time. The regularities of the manifestation of the FFV effect are determined depending on the value of the local pressure force and the...

The impact of additives addition on the combustion behavior of biomass with high content in ash-forming species is evaluated in this review. Their influence on both emissions (particulate matter and gaseous emissions) and deposits formation (fouling and slagging) are here considered. The uncertainty in the availability, under current sustainability...

In this work, the first experimentally discovered effect of flexophotovoltaics (FPV) in silicon p-n-structures under the influence of local mechanical stress on the frontal surface is theoretically substantiated.. The regularities of the manifestation of the FPV effect are determined depending on the magnitude of the local pressure force and the in...

In this work, the experimentally discovered effect of flexophotovoltaics (FFV) in silicon p-n structures under the influence of local mechanical stress on the front surface is theoretically justified for the first time. The regularities of the manifestation of the FFV effect are determined depending on the value of the local pressure force and the...

A fundamental understanding of the sizing process is a key element for sizing affordable, reliable, and sustainable nano/micro-off-grid systems. Nevertheless, the openness and transparency of modeling approaches are still low and open-source tools are scarce in this field. In this study, an open-source modeling tool for the optimization of renewabl...

In order to describe the evaporation of potassium chloride (KCl) from biomass ash at ash-heating stage during biomass combustion, the ashes of pure corn stover and wheat straw and their mixtures with potassium chloride were heated in a simultaneous thermal analyzer (STA) and tube furnace (TF) at different temperatures. The evaporation behavior of K...

For many arid countries, desalination is considered as the final possible option to ensure water availability. Although seawater desalination offers the utilisation of almost infinite water resources, the technology is associated with high costs, high energy consumption and thus high carbon emissions when using electricity from fossil sources. In o...

Several types of salts coexist in biomass and eutectic melting often occurs during combustion. The effect of eutectic melting on evaporation of salts is not well understood. The objective of this study is to investigate the interaction of two typical salts–potassium chloride (KCl) and potassium sulphate (K2SO4)–and the effect of eutectic melting on...

Waste transport plays an important role in the decarbonization of the transport sector. In this article, diesel-powered collections vehicle (dWCV) and electric waste collections vehicle (eWCV) and their operation are analyzed regarding energy demand and total cost of ownership (TCO) integrating well-to-wheel emission costs. Furthermore, an open-sou...

Driven by a society that is becoming more aware of the environment over the recent decades, biomass use has increased on both the domestic and industrial scales. In addition, the ease of the use of biomass as a transition fuel in non-renewable solid fuel installations has contributed to this rising trend. Nevertheless, the use of biomass presents s...

In this study an intelligent energy supply system is developed. Energy is obtained by wind or solar radiation and stored to cover the electricity and heat demand of a detached house in Germany. For this a heat pump and a storage tank is used. The simulation shows strategies to integrate renewable energies in different regions of Germany while dimin...

The use of producer gas from a biomass gasifier for further upgrading to liquid or gaseous ‘fuel’, e.g. via Fischer-Tropsch synthesis or methanation, or for its use in engines often requires a virtually tar-free gas. A major effort must be put into gas cleaning without being able to properly monitor the performance of this equipment in real-time. E...

Based on methane from renewable resources, LNG is an alternative fuel for heavy and long-distance traffic in land transport. Contrary to its positive properties, the fuel contains risks from an explosion and extremely low temperatures for personal and infrastructure safety. CFD-models are suitable for doing risk analyses for arbitrary scenarios. Fo...

In order to clarify the key factors of problems in combustion of herbaceous biomass, soluble and insoluble fractions of corn stover, wheat straw and rice straw pre and post combustion were prepared and examined. Elemental contents, components of the samples and mass-loss/heat-effect at heating stage of the samples were measured using X-ray fluoresc...

In order to get information about the release of potassium during combustion of herbaceous biomass, the chemical form of potassium in corn stover was identified and it was found that most potassium exists as potassium chloride (KCl). Based on this, release of KCl at normal combustion temperatures was measured using simultaneous thermal analysis, an...

Hydroliquefaction is a possible pathway to produce liquid transportation fuels from solid feedstocks like coal or biomass. Though much effort has been put into the investigation of maximizing the oil yield using expensive catalysts and pasting oils in batch setups, little is known about how to commercialize the process. This work aims at the demons...

The influence of inorganic species content on the slow pyrolysis of thermally thick wood particles has been investigated with the application of laser-based spectroscopic techniques. Infrared laser absorption and laser-induced fluorescence were used to characterize, on-line and in situ, the release of permanent gases (CO and CH 4 ) and of species e...

Further advances in the utilization of biomass-based gaseous fuels in combustion systems require a deeper understanding of the combustion chemistry behind, as well as of the coupling of the chemistry with physical phenomena such as turbulence. The former is investigated in the present study combining both experiments with numerical simulations of d...

In order to get sufficient information on biomass ash for its fertilizer application, sequential extraction method was adopted for its measurement and appropriate solvents were selected to embody its nutrition characteristics. A matrix was proposed to describe the mobility of nutrients in the ash. Based on this, fertilizer property of the ash from...

The impact of conversion process parameters in pyrolysis (maximum temperature, inert gas flow rate) and hydrothermal carbonization (maximum temperature, residence time and post-washing) on biochar and hydrochar properties is investigated. Pine wood (PW) and corn digestate (CD), with low and high inorganic species content respectively, are used as f...

The slow pyrolysis behaviour of thermally thick wood particles is investigated at 5, 10 and 20 °C/min, combining an advanced single-particle experimental approach with a detailed numerical model. Infrared laser absorption spectroscopy (IRLAS) and laser-induced fluorescence spectroscopy (LIF) are used to characterize on-line and in-situ the evolutio...

Enzymatic hydrolysis process of lignocellulosic biomass materials is difficult because of inherent structural features of biomass, which represents barriers that prevent complete hydrolysis; therefore, pretreatment techniques are necessary to render biomass highly digestible in enzymatic hydrolysis process. In this research, (non?) oxidative short-...

Infrared laser absorption spectroscopy (IRLAS) and laser-induced fluorescence spectroscopy (LIF) are applied in the present study for online in-situ characterization of volatiles products in the close vicinity of a single pyrolysing wood sphere. These advanced analytical techniques are combined with online measurements of temperature and mass evolu...

The influence of heterogeneous secondary reactions on char oxidation reactivity, which can take place during slow pyrolysis processes in a woody biomass particle, is analyzed in this study. To this end, the oxidative behavior of primary char produced in a thermo-balance with initial wood masses of a few mg is compared with the behavior of char prod...

In the paper catalytic hydrogenation of natural bitumen (NB) of Kazakhstan oil sands were investigated. The process provided under 350 bar of H2 pressure and a temperature of 430 °C. At the experiment activated carbon supported catalyst was used. It has 699.807 m²/g of surface area and 0.0635 nm of medium pore size. In the processes the yield of hy...

Extraction and Thermal Processing of Beke Oil Sands

Catalytic Hydrogenation of Oil Sand’s Natural Bitumen

To understand the complex reaction mechanisms involved in biomass pyrolysis, volatile products are characterized on-line by laser-induced fluorescence (LIF), together with on-line measurements of permanent gases by GC-TCD (Gas Chromatograph-Thermal Conductivity Detector) and temperature evolutions in the bed. The focus is to determine the component...

The overall energy demand of data centers (DCs) is still rising dramatically. Since a DC’s cooling system (CS) is a large energy consumer, reducing its demand is a key element for improving the DC’s overall energy efficiency. Integrating an aquifer thermal energy storage (ATES) in DC’s CS can help cutting the DC’s energy demand drastically. However...

The efficiency of wood gasification can be improved by applying membrane based gas separation operations in several of its sub-processes. In the present study the use of membranes made of hardened cement pastes for this purpose was investigated to provide a low cost alternative to conventional membrane materials. The pastes were tested for their di...

In the paper separation methods of organic part from oil sands were investigated at experimantally. For the determination of organic part (liquid fraction) of oil sands the extraction methods was used in Soxhlet apparatus by solvent. Thermal processing was carried out with a monotonic heating of oil sands from room temperature to 560 ⁰C. As showing...

The thermal desalination systems like multi-effect distillation and multi-stage flush have gone through a strong development process to increase energy efficiency and to improve energy recovery. While these improvements have led to lowered energy consumption, different concepts could be necessary to adapt the thermal desalination systems to renewab...

This chapter gives an overview of related research and outlines the methods applied in the present study. The study is analysing three real case biomass supply chains with an in-depth assessment of individual variables underlying actual market actions. Because of increasing biomass resources and recent dominance over pellet imports into the Europea...

This chapter describes the three chosen case studies for biomass supply from Canada, Australia, and Russia to the EU. The case studies contain a detailed cost outline from biomass resource to final consumer for the year 2011. The supply patterns include raw material, pellet production phase, transportation and shipping to the EU, delivery to the co...

This chapter deals with the evaluation of most crucial supply risks, which exist under real market conditions in the biomass market. General risk parameters and relevant indices along the biomass supply chain are discussed in detail. A modelling of 10-year-price variations based on the three investigated supply chains is followed and current 3-year...

This chapter summarises how market aspects affect total biomass supply chain economics and how highly volatile prices influence pellet supply costs. The individual ranges of price variations in a 3- to 10-year period are outlined with raw material prices, freight rates, and exchange rates between origin currency and Euro as the predominant factors....

Consolidated industrial application of biomass thermochemical conversion processes, such as pyrolysis and gasification, requires the development and application of control and optimization techniques. To this end, on-line process characterization, regarding mainly product distribution and composition under similar conditions as the ones encountered...

Gas separation is a key issue in various industrial fields. Hydrogen has the potential for application in clean fuel technologies. Therefore, the separation and purification of hydrogen is an important research subject. CO2 capture and storage have important roles in “green chemistry”. As an effective clean technology, gas separation using inorgani...

In the paper physical and chemical properties of natural bitumen of oil sands were investigated. For the determination of organic part (natural bitumen) of oil sands the extraction methods was used in Soxhlet apparatus by solvent. Physical and mechanical characteristics of natural bitumen (NB) are established by standard methods: softening temperat...

Steigender Energiebedarf der Informations- und Kommunikationstechnologie (IKT) auf der einen und stark steigende Energiepreise auf der anderen Seite, zwingen zu einer immer energieeffizienteren Nutzung der IKT. Um die Effizienz der Energienutzung bewerten zu können, ist eine umfassende Überwachung des Energiebedarfs der IKT-Infrastruktur (Energiemo...

The article presents results from various subprojects of the project "High Tech - Low Ex: Energieeffizienz Berlin Adlershof 2020".

p>In the paper microscopic structure and physicochemical characteristics of asphaltenes were investigated. Asphaltene was precipitated from natural bitumen of oil sand of Munaily-Mola deposit using organic solvent of petroleum ether. According to results of our work, we found that the largest yield of asphaltens was reached by using the petroleum e...

In the paper physicochemical properties of oil sands of Munayli-Mola deposits and efficient ways to use them for preparing asphalt concrete were represented. For determination of organic part of oil sands the extraction methods were used in Soxhlet apparatus by variety of solvents. It has been established 16 wt.% content of natural bitumen in oil s...

Microalgae are discussed as an alternative source for the production of biofuels. The lipid content compared to cultivation time of used species is the main reason for any choice of a special strain. This paper reviews more analytical data of 38 screened microalgae strains. After the cultivation period, total content of lipids was analysed. The ext...

Background Islands often depend on the import of fossil fuels for power generation. Due to the combined effect of high oil prices and transportation costs, energy supply systems based on renewable energies are already able to compete successfully with fossil fuel systems for a number of these islands. Depending on local and regional conditions, not...

Introduction Packed bed reactors are widely used in the chemical and process industry amongst others for catalytic surface reactions. The model based design of such reactors is often done with simplifications, e.g. plug flow and an equally distributed porosity over the whole packed bed which are not valid for reactors with a small tube to particl...

Seawater desalination in the capacity range 100–1000 m/day is globally of increasing importance, especially when it comes to in remote costal regions. By meeting the energy demand of desalination plants by using renewable energy technologies, the environmental impact can be minimised. For water production of more than a few cubic meters per day, us...

The goal of the project presented here was the collaborative development, investigation and evaluation of gas cleaning components for processing and conditioning producer gases thermochemically generated from biomass. For this particular purpose a modular and adaptable product gas cleaning concept has been projected jointly by the above mentioned p...

An experimental investigation of separation control using steady and pulsed dielectric barrier discharge actuators was carried out on an Eppler E338 airfoil at typical micro air vehicle Reynolds numbers (20,000≤Re≤140,000). Pulsing was achieved by modulating the high frequency plasma excitation voltage. The actuators were calibrated directly using...

A kinetic model of smouldering of pine wood is determined by thermo-gravimetric analysis (TGA), describing the reactions of wood pyrolysis, wood oxidation and char oxidation. Thermo-gravimetric experiments were conducted with constant heating rates ranging from 2.5 to 10 K/min in atmospheres of pure nitrogen and mixtures of nitrogen and oxygen (wit...

Der Beitrag thematisiert Untersuchungen zu einem effektiven, modularen Konzept zur Gasreinigung in Anlagen zur thermochemischen Gaserzeugung aus nachwachsenden Rohstoffen. Ziel war es, neue und bewährte apparative Konzepte so zu kombinieren, dass ein funktionsfähiges und an viele Anlagentypen und -größen anpassbares System entsteht. Die Führung des...

The poor heat transport in packed-bed reactors is one of the major drawbacks of this reactor type. This characteristic is to some extent due to the non-homogeneous lateral void fraction distribution (VFD) in a tubular packed bed. The objective of this work was to find out, firstly, if it is possible to obtain more homogeneous VFDs in monodisperse p...

Nicht erst seit Beginn des 21. Jahrhunderts stehen »Neue Technologien« im Fokus der Öffentlichkeit. Von der Kernenergie über die Mikroelektronik bis hin zur Bio- und Nanotechnologie und dem Internet scheinen sie die Möglichkeitshorizonte moderner Gesellschaften zu definieren. Die Debatten um »Neue Technologien« erlauben deshalb Einblick in zentrale...

Combining a volume reaction model and front reaction approximation is proposed to simulate the combustion of a large biomass particle. Two intraparticle processes—drying and char oxidation—are simplified as front reaction because they are transport controlled. The other intraparticle process—pyrolysis—is described as the volume reaction because it...

The natural smoldering of a packed bed of wood char granules was investigated experimentally. Parameters characterized experimentally included two types of ignition heaters (a rod heater and a plate heater), a range of four particle sizes (< 1, 1-2, 2-3, and <3 mm), different fuel bed heights, and different ignition temperatures. The temperature in...

Laser-induced fluorescence (LIF) is a viable technique for qualitative and quantitative analysis of polycyclic aromatic hydrocarbons (PAH). An analytical tool for a nearly continuous analysis of gas-phase PAH based on LIF was designed and built. The author's intention is to further analyse complex mixtures containing PAH such as tar from gasificati...

We present an Eulerian multiphase approach for modeling the gasification of wood in fluidized beds. The kinetic theory of granular material is used to evaluate constitutive properties of the dispersed solid phase. Comprehensive models for wood pyrolysis, char gasification and homogeneous gas phase reactions are taken into account. The dispersed sol...

Der Vergasung von Biomasse zur Gewinnung von Brenn- und Synthesegas für die effiziente direkte Bereitstellung von Elektrizität und Wärme/Kälte oder aber der Herstellung von chemischen Energieträgern bzw. Energiespeichermedien (Methan (SNG), Methanol, Fischer-Tropsch-Kraftstoff) wird ein großes Potenzial zuerkannt. Triebkräfte der derzeitigen Entwic...

If substantial amounts of CO2, which according to actual scenarios may in the future be captured from industrial processes and power generation, shall be utilized effectively, scalable energy efficient technologies will be required. Thus, a survey was performed to assess a large variety of applications utilizing CO2 chemically (e.g., production of...

Analysis and monitoring of tar in producer gases is a topic going along with the efforts to reduce tar levels in biomass gasification processes. Well established methods such as tar guideline (CEN/TS 15439) or the SPA­method allow for comparable results when operated well by trained personnel and the samples being analyzed in experienced laboratori...

Goal of this project is the collaborative development, investigation and evaluation of gas cleaning components for the cleaning and conditioning of biomass producer gases in collaborative work. Three main partners TU Berlin (Germany), University of Nottingham (UK) and Beth Filtration GmbH (Germany) as well as subcontractors Eckrohrkessel GmbH (Germ...

Goal of this project is the collaborative development, investigation and evaluation of gas cleaning components for the cleaning and conditioning of biomass producer gases in collaborative work. Three main partners TU Berlin (Germany), University of Nottingham (UK) and Beth Filtration GmbH (Germany) as well as subcontractors Eckrohrkessel GmbH (Germ...

Teer ist im Bereich der Biomassevergasung der Problemstoff, der die erfolgreiche Kommerzialisierung der Prozesse sehr erschwert und teilweise ganz verhindert hat. Die erforderliche Gasreinigung ist aufwändig und die Investitionskosten von Vergasungsanlagen sind deshalb vergleichsweise hoch. Um die Teerproblematik an den diversen Versuchs-, Demonstr...

In this work we compare two different modelling strategies for the simulation of wood gasification in a dense fluidized bed. In the first method we adopt an Euler-Lagrange approach where the fluid phase is modelled as a continuum and the particulate phase is modelled on the individual particle level using the Discrete Element Method (DEM). In the s...

The further development of gasification technology for biomass for various sizes of gasifiers and differrent end uses needs detailed information about the product gas com-position. This is especially the case for unwanted by-products like tar. An online analysis system is applied making use of a combination of gas chromatogra-phy (GC) and laser mas...

Natural forward smoldering (which normally occurs in thermochemical conversion of solid fuel) and natural reverse smoldering (which normally occurs in self-ignition fire in piled materials) have been compared theoretically using the volume reaction method. One-dimensional vertical propagation of piled char powder smoldering was used as the model ca...

Smoldering combustion in a packed bed of carbonaceous material is a very complex process, where numerous physical and chemical parameters are involved. This study was conducted to examine the impact of several physical parameters on the behavior of natural downward smoldering. For that purpose, a one-dimensional homogeneous model has been developed...

We present an Euler–Lagrange method for the simulation of wood gasification in a bubbling fluidized bed. The gas phase is modeled as a continuum using the 2D Navier–Stokes equations and the solid phase is modeled by a Discrete Element Method (DEM) using a soft-sphere approach for the particle collision dynamic. Turbulence is included via a Large-Ed...

Laser-induced fluorescence (LIF) is a viable technique for qualitative and quantitative on-line-analysis of aromatic and polycyclic aromatic hydrocarbons (PAH) in tar vapours present in the gas phase of gasification systems. A LIF based analytical tool for on-line tar analysis was designed and manufactured. Different tar model compounds were analyz...

The ability of char to reduce tar is well known. In this approach a fluidized bed gasifier was operated with charcoal as bed material. Aspects of fuel preparation, gasifier operation and the influence on the tar content are presented in this paper. Tar analysis was carried out with online GC/MS measurements and for comparison the setup according to...

We present an Euler-Lagrange method for the simulation of wood gasification in a bubbling fluidized bed. The gas phase is modeled as a continuum and the solid phase is modeled by a Discrete Element Method (DEM) using a soft sphere approach for the particle collision dynamic. The model takes into account detailed gas phase chemistry, zero- dimension...