Tilman Barz

Tilman Barz
AIT Austrian Institute of Technology | ait · Center for Energy

PhD

About

92
Publications
18,581
Reads
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823
Citations
Citations since 2017
42 Research Items
628 Citations
2017201820192020202120222023050100150
2017201820192020202120222023050100150
2017201820192020202120222023050100150
2017201820192020202120222023050100150
Additional affiliations
January 2008 - December 2014
Technische Universität Berlin
Position
  • PostDoc Position

Publications

Publications (92)
Conference Paper
Full-text available
slPCMlib predicts the effective thermal properties of solid/liquid phase change materials (PCM) showing a non-isothermal phase transition behavior. The effective properties are valid over the PCM functional temperature range where latent heat is absorbed and released. Different phenomenological phase transition models are implemented to account for...
Conference Paper
Full-text available
slPCMlib predicts the effective thermal properties of solid/liquid phase change materials (PCM) showing a non-isothermal phase transition behavior. The effective properties are valid over the PCM functional temperature range where latent heat is absorbed and released. Different phenomenological phase transition models are implemented to account for...
Article
Full-text available
Modern biotechnological laboratories are equipped with advanced parallel mini‐bioreactor facilities that can perform sophisticated cultivation strategies (e.g. fed‐batch or continuous) and generate significant amounts of measurement data. These systems require not only optimal experimental designs that find the best conditions in very large design...
Preprint
Full-text available
Modern biotechnological laboratories are equipped with advanced parallel mini-bioreactor facilities that can perform sophisticated cultivation strategies (e.g. fed-batch or continuous) and generate significant amounts of measurement data. These systems require not only optimal experimental designs that find the best conditions in very large design...
Article
Full-text available
In heat flux differential scanning calorimetry, a pair of identical crucibles, one empty as reference and the other filled with the sample, is heated in a furnace with a prescribed rate. The (empty) reference crucible heats faster, resulting in a temperature difference that is detected by thermocouples. Slow heating of the furnace results in weak a...
Preprint
We discuss the application of a nonlinear model predictive control (MPC) and a moving horizon estimation (MHE) to achieve an optimal operation of E. coli fed-batch cultivations with intermittent bolus feeding. 24 parallel experiments were considered in a high-throughput microbioreactor platform at 10 mL scale. The robotic island in question can run...
Preprint
Full-text available
Modern biotechnological laboratories are equipped with advanced parallel mini-bioreactor facilities that can perform sophisticated cultivation strategies (e.g. fed-batch or continuous) and generate significant amounts of measurement data. These systems require not only optimal experimental designs that find the best conditions in very large design...
Preprint
Full-text available
Modern biotechnological laboratories are equipped with advanced parallel mini-bioreactor facilities that can perform sophisticated cultivation strategies (e.g. fed-batch or continuous) and generate significant amounts of measurement data. These systems require not only optimal experimental designs that find the best conditions in very large design...
Article
Full-text available
Mechanistic model-based methods are indispensable tools for characterization, monitoring and control in biopharmaceutical industry. However, the complexity of mechanistic models is restricted by the availability of process analytics. As a result, biological reactions are often lumped and only central metabolic pathways and extracellular analytics a...
Chapter
Laboratory automation that drives integrated miniaturized and parallel reactor systems incorporating analytical devices for online reaction monitoring has reached a remarkable level of sophistication. The result is a significant increase in experimental throughput allowing the generation of large amounts of data under complex experimental settings...
Chapter
Bioprocess development is commonly characterized by long development times, especially in the early screening phase. After promising candidates have been pre-selected in screening campaigns, an optimal operating strategy has to be found and verified under conditions similar to production. In view of the large number of strains and the process condi...
Article
High throughput experimental systems play an important role in bioprocess development, as they provide an efficient way of analysing different experimental conditions and perform strain discrimination in previous phases to the industrial scale production. In the millilitre scale, these systems are combinations of parallel mini-bioreactors, liquid h...
Article
Optimal experimental design for parameter precision attempts to maximize the information content in experimental data for a most effective identification of parametric model. With the recent developments in miniaturization and parallelization of cultivation platforms for high-throughput screening of optimal growth conditions massive amounts of info...
Preprint
Full-text available
High throughput experimental systems play an important role in bioprocess development, as they provide an efficient way of analysing different experimental conditions and perform strain discrimination in previous phases to the industrial scale production. In the millilitre scale, these systems are combinations of parallel mini-bioreactors, liquid h...
Preprint
Full-text available
Bioprocess development is commonly characterized by long development times, especially in the early screening phase. After promising candidates have been pre-selected in screening campaigns, an optimal operating strategy has to be found and verified under conditions similar to production. Cultivating cells with pulse-based feeding and thus exposing...
Preprint
Optimal experimental design for parameter precision attempts to maximize the information content in experimental data for a most effective identification of parametric model. With the recent developments in miniaturization and parallelization of cultivation platforms for high-throughput screening of optimal growth conditions massive amounts of info...
Article
Full-text available
Heat pumps with a three-media refrigerant/phase change material (PCM) water heat exchanger (RPW-HEX), integrated in the hot superheated section after the compressor, have a promising potential for electric energy savings. The RPW-HEX operates as a desuperheater that stores the sensible energy provided by the hot gas during heating and cooling opera...
Conference Paper
Latent heat thermal energy storage (LHTES) bears the advantage of high energy storage density and balancing demand and supply. A promising application for residential buildings is the use of a compression heat pump (HP) in combination with a LHTES to generate domestic hot water (DHW) with the aid of the hot refrigerant compressor discharge. In this...
Article
Full-text available
Technical-grade and mixed solid–liquid phase change materials (PCM’s), such as commercial paraffins, can show a complex non-isothermal phase transition behavior, possibly with hysteresis and supercooling, two-step transitions and asymmetric phase transition peaks. Phenomenological modeling approaches can use data-driven methods to derive phase tran...
Chapter
The use of autosamplers connected to high throughput analytical devices allows for a high sampling frequency and analytics with reduced manual labor, leading to better process characterization (Maurer et al., 2015; Hofer et al., 2020). Increased sampling often leads to a significantly increased information content in the generated data. However, in...
Chapter
The open-ended complexity of abiotic conditions in bioreactors means that it is generally infeasible to model its dynamic behaviour comprehensively. Learning optimization oriented probabilistic models encoding a parsimonious representation is far more efficient for bioprocess development and optimization. In this work, active inference is integrate...
Article
Full-text available
Thermal energy storages with phase change materials (PCM's) based on plate-fin and tube-fin (gas-to-liquid) heat exchanger (HEX) designs show a comparatively high heat transfer performance and compactness. High heat transfer rates allow for optimal storage designs and operation close to the PCM's phase change temperature. However, industrial-grade...
Article
Full-text available
In bioprocess development, the host and the genetic construct for a new biomanufacturing process are selected in the early developmental stages. This decision, made at the screening scale with very limited information about the performance in larger reactors, has a major influence on the efficiency of the final process. To overcome this, scale-down...
Article
Full-text available
Integration of a three-media refrigerant/phase change material (PCM)/water heat exchanger (RPW-HEX) in the hot superheated section of a heat pump (HP) system is a promising approach to save energy for domestic hot water (DHW) generation in multi-family houses. The RPW-HEX works as a desuperheater and as a latent thermal energy storage in the system...
Article
Full-text available
The area-proportional baseline method generates phase fraction–temperature curves from heat capacity data of phase change materials. The curves describe the continuous conversion from solid to liquid over an extended temperature range. They are consistent with the apparent heat capacity and enthalpy modeling approach for the numerical solution of h...
Preprint
Full-text available
In bioprocess development, the host and the genetic construct for a new biomanufacturing process are selected in the early developmental stages. This decision, made at the screening scale with very limited information about the performance of the selected cell factory in larger reactors, has a major influence on the performance of the final process...
Conference Paper
Off-gas measurements give valuable information on the respiratory activity of organisms during fermentation processes. Measured oxygen consumption and carbon dioxide production is usually linked to the overall metabolic activity of the cultivated cells. Together with offline measured nutrient and metabolite concentrations reaction parameters of gro...
Article
Full-text available
Monitoring of the state of charge of the thermal energy storage component in solar thermal systems for space heating and/or cooling in residential buildings is a key element from the overall system control strategy point of view. According to the literature, there is not a unique method for determining the state of charge of a thermal energy storag...
Article
This paper presents two nonlinear model predictive control based methods for solving closed-loop stochastic dynamic optimisation problems, ensuring both robustness and feasibility with respect to state output constraints. The first one is a new deterministic approach, using the wait-and-see strategy. The key idea is to specifically anticipate viola...
Article
Full-text available
Technical-grade and mixed solid/liquid phase change materials (PCM) typically melt and solidify over a temperature range, sometimes exhibiting thermal hysteresis. Three phenomenological phase transition models are presented which are directly parametrized using data from complete melting and solidification experiments. They predict hysteresis pheno...
Conference Paper
This contribution presents a concept for the direct integration of a refrigerant/water Heat Exchanger (HEX) with a Phase Change Material (PCM) in the hot superheated section of an R32 - air source compression Heat Pump (HP) cycle, for optimized Domestic Hot Water (DHW) generation in multi-family houses. The concept takes advantage of the PCMs high...
Conference Paper
Full-text available
Thermal energy storage technologies through solid/liquid phase change materials (PCMs) use the thermodynamic principles of melting and solidification to absorb and release thermal energy. In the ideal case, this technology allows to charge and discharge relatively high amounts of thermal energy at a constant, unique temperature. However, for most c...
Article
Full-text available
Especially in biomanufacturing, methods to design optimal experiments are a valuable technique to fully exploit the potential of the emerging technical possibilities that are driving experimental miniaturization and parallelization. The general objective is to reduce the experimental effort while maximizing the information content of an experiment,...
Article
Currently applied methods for characterization and optimization of bio-pharmaceutical processes are still strongly empirical. This often involves Design of Experiment (DoE) methods that require a large number of time-consuming experiments and can hardly fulfill the requirements of ‘Quality by Design’ (QbD). Linking mathematical models with experime...
Article
Full-text available
Latent heat storages using phase change materials (PCM) ideally store and release heat at an almost constant, unique temperature. However, most industrial grade solid/liquid PCM melt and solidify over a temperature range in which both phases coexist, and hysteresis in the phase transition sometimes significantly increases this non-ideal behavior. M...
Article
Full-text available
Advanced robotic experimental facilitiessignificantly reduce the time spans fromproduct discovery to biomanufacturing bytheir high automation level. The experi-mental design on these facilities has to beoptimally designed and carried out whilecomplying with tight operational restric-tions. Due to the nonlinear dynamics ofbioprocesses and the import...
Article
Full-text available
A nonlinear state observer is designed for a thermal energy storage with solid/liquid phase change material (PCM). Using a physical 2D dynamic model, the observer reconstructs transient spatial temperature fields inside the storage and estimates the stored energy and the state of charge. The observer has been successfully tested with a lab-scale lat...
Article
Results are presented from the optimal operation of a fully automated robotic liquid handling station where parallel experiments are performed for calibrating a kinetic fermentation model. To increase the robustness against uncertainties and/or wrong assumptions about the parameter values, an iterative calibration and experiment design approach is...
Article
Pyrimidine and purine nucleoside phosphorylases catalyze the reversible phosphorolytic cleavage and formation of the glycosidic bond of purine and pyrimidine nucleosides, respectively, and are thus, key catalysts for the synthesis of new compounds. The selection of the best combination of enzyme and reaction conditions is not trivial, as each of th...
Chapter
The accurate modelling of thermo-physical properties of phase change materials (PCM) used in latent heat thermal energy storages (LHTES) is a challenging task. PCM properties are strongly affected by the phase transition, and possibly by additional complex phenomena, such as hysteretic behaviour due to subcooling or kinetics due to limited crystal...
Patent
AT 518791 A4 2018-01-15 ---------------------------------------------------------------------- VERFAHREN ZUM BESTIMMEN EINES LADEZUSTANDES EINES LATENTWÄRMESPEICHERS ---------------------------------------------------------------------- Es wird ein Verfahren zum Bestimmen eines Ladezustandes eines Latentwärmespeichers (1) vorgeschlagen, wobei in de...
Article
We present an integrated framework for the online optimal experimental re-design of parallel nonlinear dynamic processes that aims to precisely estimate the parameter set of macro kinetic growth models with minimal experimental effort. This provides a systematic solution for rapid validation of a specific model to new strains, mutants, or products....
Article
Full-text available
Thermal storages are part of highly integrated energy systems. The development of accurate and reduced models is critical for efficient simulations on a system-level and the analysis of the storage design, control and integration. We present the experimental analysis and numerical modeling of a lab-scale shell and tube latent heat thermal energy s...
Article
Full-text available
The adaptive input design (also called online redesign of experiments) for parameter estimation is very effective for the compensation of uncertainties in nonlinear processes. Moreover, it enables substantial savings in experimental effort and greater reliability in modeling. We present theoretical details and experimental results from the real-ti...
Article
Full-text available
Discrete ill-posed problems are often encountered in engineering applications. Still, their sound analysis is not yet common practice and difficulties arising in the determination of uncertain parameters are typically not assigned properly. This contribution provides a tutorial review on methods for identifiability analysis, regularization techniqu...
Article
In this paper, a general dynamic model of a pseudo-homogeneous catalytic plug flow reactor (PFR) is developed, which does not apply the traditional assumption of negligible difference between enthalpy and internal energy inside its energy balance. Such a model is then compared to a second dynamic PFR model, whose energy conservation equation identi...
Article
Optimal aeration control strategies for sequencing Batch Reactors in WWT with Bypass Nitrification are studied. The operation is defined alternating aerobic and anoxic phases with high frequency. The controlled variable, the aeration, can only adopt fixed values, on and off, leading to a discrete trajectory of bang-bang type. The problem is to comp...
Conference Paper
Full-text available
Within the Collaborative Research Center InPROMPT / TRR 63 in Germany the process concept known as hydroformylation in microemulsions is investigated. The aim is to perform the hydroformylation of long-chain alkenes while utilizing water-soluble rhodium-based catalysts. The surfactant enables the mixing of two immiscible liquids and after the react...
Conference Paper
Full-text available
In the Collaborative Research Center InPROMPT / TRR 63 hydroformylation in microemulsions is investigated. For this purpose, a mini-plant has been constructed at Technische Universität Berlin. This process concept has proven to be challenging from an operation point of view. Therefore, model-assisted process operating strategies are applied, to con...
Article
A fundamental practice in process engineering is monitoring the state dynamics of a system. Unfortunately, observability of some states is related to high costs, time, and efforts. The Mechanistic Event Recognition (MER) aims to detect an event (defined as a change of the system with specific significance to the operation of the process) that canno...
Article
Die optimale Versuchsplanung ist ein methodischer Ansatz zur Kalibrierung und Validierung von Modellen mit experimentellen Daten. Sie besitzt ein großes Potenzial zur Reduktion des experimentellen Aufwands und zur Maximierung der Modellgenauigkeit. In dieser Arbeit werden jüngste Entwicklungen zur Verbesserung der Adaptivität der Methodik diskutier...
Conference Paper
In this work, an approach is proposed for the implementation of an optimal aeration control strategy for Waste Water Treatment in a SBR (Sequencing Batch Reactor) for dual nitrification-denitrification [1]. The optimal numbers of aeration-anoxic intervals as well as the duration of each interval are to be determined. Thus, two different objectives...
Article
Full-text available
A model-based experimental design is formulated and solved as a large-scale NLP problem. The key idea of the proposed approach is the extension of model equations with sensitivity equations forming an extended sensitivities-state equation system. The resulting system is then totally discretized and simultaneously solved as constraints of the NLP pr...
Conference Paper
Mathematical models are essential for chemical processes since they contribute to both identification and manipulation of process mechanisms, e.g. in reaction systems, separation processes and process controls. The methodologies of model-based experiment design aim at reducing the uncertainties of estimated model parameters, and thus, make the iden...
Article
Full-text available
The online redesign of experiments for parameter determination of nonlinear dynamic systems has been studied recently by different research groups. In this article, this technique is assessed in a real case study for the first time. The presented algorithm adopts well-known concepts from model-based control. Compared to previous studies, special at...
Article
Full-text available
In this work, a methodology for the Model-Based Identifiable Parameter Determination (MBIPD) is presented. This systematic approach is proposed to be used for structure and parameter identification of nonlinear models of biological reaction networks. Usually this kind of problems are over-parameterized with large correlations between parameters. He...
Conference Paper
We present an approach to closed-loop online model-based redesign of experiments for system identification. Special attention is given to the compliance with safety restrictions and operating requirements during online experiments. For doing so, we propose the integration of a controller into the system identification algorithm. To avoid numerical...
Article
The accurate and efficient evaluation of first and higher order derivative information of mathematical process models plays a major role in the field of Process Systems Engineering. Although it is well known that the chosen methods for derivative evaluation may have a major impact on solution efficiency, a detailed assessment of these methods is ra...
Article
Full-text available
In this work, an approach to the forward generation of discrete first- and second-order sensitivities is proposed. For this purpose, an algorithm has been developed, which can basically be applied to general implicit differential-algebraic equation (DAE) systems. Moreover, the approach has been tailored to both the generation of directional derivat...
Conference Paper
An important aspect for model-based design and development as well as for process monitoring and control is the consideration of uncertain process parameters. One approach for the explicit consideration of such uncertainties is the formulation of Chance-Constrained optimization problems. Within the last years, several different methods for the effi...
Conference Paper
Operators in chemical plants are confronted with several different measured process variables and parameters. Although the precision of measuring rose, individual measurements remained uncertain. This might affect real measurements such as temperature or pressure, where the measured value is more an expected value, with the real value within a rang...
Article
In this work, an approach for the forward integration of first and second order sensitivities for dynamic simulation and optimization problems is presented. The implementation is done following the idea of internal numeric differentiation. The integration of the dynamic system is done by an implicit Runge-Kutta discretization of the state equations...
Article
In this work, a new modeling environment called MOSAIC is presented, which combines well known concepts such as equation-based modeling, use of symbolic mathematic language, and code generation. Moreover, the proposed tool follows a new modeling approach for the re-use of single equations and the support of different naming conventions. The modelin...
Conference Paper
Nowadays, the process industry is highly competitive and has to fulfill high quality standards for their products. Therefore, the use of computer-aided optimization software became an integral part of today’s planning in process industries. The increase of available computing power and important advancements in algorithms led to more and more compl...