@misc{JanaChauhanMuthukumaretal., author = {Jana, Sayantan and Chauhan, Nikhil and Muthukumar, Palanisamy and R{\"o}ntzsch, Lars}, title = {Transient analysis and performance prediction of a metal hydride based thermal energy storage system with Integrated cooling and heat upgradation}, series = {Heat transfer engineering : an international journal}, journal = {Heat transfer engineering : an international journal}, publisher = {Taylor \& Francis}, address = {London}, issn = {0145-7632}, doi = {10.1080/01457632.2025.2521599}, pages = {1 -- 13}, abstract = {This work embodies a numerical model development and simulation of a metal hydride-based thermal energy storage system with integrated cooling as well heat upgradation. The concept of this system is unique as it operates on thermal drive during the energy storage cycle while during the energy release cycle it is compressor-operated. The utility of the mechanical compressor in the system is two-fold i.e., one operation mode would harness cooling, and another operation mode would fetch heat upgradation. The numerical model devised is a lumped parameter model which solves for hydrogen concentration and temperature of the linked metal hydride reactors. The proposed thermal energy storage system is of 5 MJ capacity which engages tube bundle reactor settings for both high-temperature and low-temperature hydride alloys. Each energy storage and release cycles are simulated for a fixed duration of 10000 s. For a fixed heat supply and heat recovery temperatures of 623 K and 573 K, the system offered cooling coefficient of performance in the range of 1.43-1.58 at 283-293 K. Also, approximately 77\% of the energy stored at 623 K could be retrieved at 573 K. In heat upgradation operation mode, 10-30 K temperature lift was accomplished.}, language = {en} } @misc{SakkasAbang, author = {Sakkas, Nikolaos Panagiotis and Abang, Roger Atini}, title = {Thermal load prediction of communal district heating systems by applying data-driven machine learning methods}, series = {Energy Reports}, volume = {8}, journal = {Energy Reports}, issn = {2352-4847}, doi = {10.1016/j.egyr.2021.12.082}, pages = {1883 -- 1895}, abstract = {Load forecasting is an essential part of the operational management of combined heat and electrical power units, since a reliable hour- and day-ahead estimation of their thermal and electrical load can significantly improve their technical and economic performance, as well as their reliability. Among different types of prediction techniques, data-driven machine learning methods appear to be more suitable for load estimation in operational systems, compared to the classical forward approach. Research so far has been concentrated mainly on the magnitude of buildings with single load types. It has only been extended to a limited degree on the level of a district heating network where several end users with different characteristics merge into one bigger scale heat consumer (city or group of communities). In this study, artificial neural networks are utilized, to develop a load prediction model for district heating networks. A segmented analytical multi-phase approach is employed, to gradually optimize the predictor by varying the characteristics of the input variables and the structure of the neural network. The comparison against the load prediction time series generated by a local communal energy supplier using a commercial software reveals that, although the latter is enhanced by manual human corrections, the optimized fully automatic predictors developed in the present study generate a more reliable load forecast.}, language = {en} } @misc{KatzerBabulKlattetal., author = {Katzer, Christian and Babul, Konrad and Klatt, Matthias and Krautz, Hans Joachim}, title = {Quantitative und qualitative relationship between swirl burner operating conditions and pulverized coal flame length}, series = {Fuel Processing Technology}, volume = {156}, journal = {Fuel Processing Technology}, issn = {0378-3820}, doi = {10.1016/j.fuproc.2016.10.013}, pages = {138 -- 155}, language = {en} } @misc{ZiemsTannertKrautz, author = {Ziems, Christian and Tannert, Daniel and Krautz, Hans Joachim}, title = {Project presentation: Design and installation of advanced high pressure alkaline electrolyzer-prototypes}, series = {Energy Procedia}, volume = {29}, journal = {Energy Procedia}, issn = {1876-6102}, doi = {10.1016/j.egypro.2012.09.087}, pages = {744 -- 753}, language = {en} } @misc{KangwanpongpanCorreadaSilvaKrautz, author = {Kangwanpongpan, Tanin and Correa da Silva, Rodrigo and Krautz, Hans Joachim}, title = {Prediction of oxy-coal combustion through an optimized weighted sum of gray gases model}, series = {Energy : the international journal}, volume = {41}, journal = {Energy : the international journal}, number = {1}, issn = {0360-5442}, doi = {10.1016/j.energy.2011.06.010}, pages = {244 -- 251}, language = {en} } @misc{MissagiaGuerreroNarraetal., author = {Missagia, Bruna and Guerrero, Cinthya and Narra, Satyanarayana and Sun, Yaoming and Ay, Peter and Krautz, Hans Joachim}, title = {Physicomechanical properties of rice husk pellets for energy generation}, language = {en} } @misc{DanilaVollmerKunz, author = {Danila, Kevin and Vollmer, Jan and Kunz, Philip}, title = {Performance evaluation of reanalysis models for upsampling of solar irradiance and wind speed data}, series = {Renewable energy}, volume = {261}, journal = {Renewable energy}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {0960-1481}, doi = {10.1016/j.renene.2026.125301}, pages = {1 -- 13}, abstract = {The transition to renewable energy sources is a cornerstone of modern energy system transformation. Yet, the integration of solar and wind power remains challenging due to limited availability of high-resolution time series data. Accurate modeling and forecasting of renewable energy generation are essential for grid stability, and the effective deployment of technologies such as water electrolysis. However, most available datasets are provided at coarse temporal resolutions, which restricts their utility for dynamic system analysis and hinders the development of robust operational strategies. This study addresses this critical gap by evaluating the performance of reanalysis models and introducing a statistical upsampling approach that generates data with 1-min resolution from reanalysis data with 1-h resolution using a first-order Markov chain Monte Carlo method. The method is validated against measured data. The normalized root-mean-square error of the simulated data is less than 10\% and the mean intra-hour standard deviation differs from 4.8\% to 9.1\% compared to measured values for solar irradiance and wind speed. The generated data facilitates the optimization of system operation, and enhances the planning of sector-coupled infrastructures. Ultimately, this approach enables reliable integration of renewable energy despite limited data availability and thus contributes to the advancement of the sustainable energy transition.}, language = {en} } @misc{AsegehegnSchreiberKrautz, author = {Asegehegn, Teklay Weldeabzgi and Schreiber, Matthias and Krautz, Hans Joachim}, title = {Numerical Study of Bubbling Gas-Solid Fluidized Beds Hydrodynamics: Influence of Immersed Horizontal Tubes and Data Analysis}, language = {en} } @misc{AsegehegnSchreiberKrautz, author = {Asegehegn, Teklay Weldeabzgi and Schreiber, Matthias and Krautz, Hans Joachim}, title = {Numerical simulation and experimental validation of bubble behavior in 2D gas-solid fluidized beds with immersed horizontal tubes}, doi = {http://dx.doi.org/10.1016/j.ces.2011.07.056}, language = {en} } @misc{SchreiberAsegehegnKrautz, author = {Schreiber, Matthias and Asegehegn, Teklay Weldeabzgi and Krautz, Hans Joachim}, title = {Numerical and Experimental Investigation of Bubbling Gas-Solid Fluidized Beds with Dense Immersed Tube Bundles}, language = {en} } @misc{KangwanpongpanFrancaCorreadaSilvaetal., author = {Kangwanpongpan, Tanin and Franca, Francis H. R. and Correa da Silva, Rodrigo and Smith Schneider, Paulo and Krautz, Hans Joachim}, title = {New correlations for the weighted-sum-of-gray-gases model in oxy-fuel conditions based on HITEMP 2010 database}, series = {International Journal of Heat and Mass Transfer}, volume = {55}, journal = {International Journal of Heat and Mass Transfer}, number = {25-26}, issn = {0017-9310}, doi = {10.1016/j.ijheatmasstransfer.2012.07.032}, pages = {7419 -- 7433}, language = {en} } @misc{NimtzKlattWieseetal., author = {Nimtz, Michael and Klatt, Matthias and Wiese, Bernd and K{\"u}hn, Michael and Krautz, Hans Joachim}, title = {Modelling of the CO2 process- and transport chain in CCS systems - Examination of transport and storage processes}, series = {Chemie der Erde - Geochemistry}, volume = {70}, journal = {Chemie der Erde - Geochemistry}, number = {3}, issn = {0009-2819}, doi = {10.1016/j.chemer.2010.05.011}, pages = {185 -- 192}, language = {en} } @misc{AhaFindeisenKrautz, author = {Aha, Ulrich and Findeisen, Alexander and Krautz, Hans Joachim}, title = {Maintenance optimization for large coal-fired power plants}, language = {en} } @misc{DanilaKunzRoentzsch, author = {Danila, Kevin and Kunz, Philip and R{\"o}ntzsch, Lars}, title = {Low-temperature electrolysis model optimized for improved performance in dynamic simulations}, series = {International journal of hydrogen energy}, volume = {223}, journal = {International journal of hydrogen energy}, publisher = {Elsevier BV}, address = {Amsterdam}, issn = {0360-3199}, doi = {10.1016/j.ijhydene.2026.154294}, pages = {1 -- 12}, abstract = {Traditional hydrogen production methods contribute significantly to greenhouse gas emissions, making technological change essential. Water electrolysis powered by renewable energy offers a promising route for sustainable hydrogen production. However, the variability of renewables challenges efficient electrolyzer operation, often requiring detailed simulations with long time series and high computational effort. We present a dynamic model of a low-temperature electrolyzer system optimized for computational efficiency. The model increases computational speed by a factor of 1000 compared to full-balance models while maintaining accuracy above 99\% in hydrogen prediction. The simplified model is used to investigate the benefits of modularization in large-scale hydrogen plants. Results show that modularization has a minor effect on overall output but significantly increases operational time. This extended production window can reduce the need for large-scale hydrogen storage, especially when integrated with a continuous hydrogen consumer.}, language = {en} } @misc{AhaFindeisenKrautzetal., author = {Aha, Ulrich and Findeisen, Alexander and Krautz, Hans Joachim and Kahlert, Joachim}, title = {Korrosion und Instandhaltungsoptimierung CO2-armer Braunkohlekraftwerke unter ge{\"a}nderten Prozessbedingungen und -parametern}, language = {de} } @misc{AsegehegnSchreiberKrautz, author = {Asegehegn, Teklay Weldeabzgi and Schreiber, Matthias and Krautz, Hans Joachim}, title = {Investigation of bubble behavior in fluidized beds with and without immersed horizontal tubes using a digital image analysis technique}, doi = {http://dx.doi.org/10.1016/j.powtec.2011.03.025}, language = {en} } @misc{AsegehegnSchreiberKrautz, author = {Asegehegn, Teklay Weldeabzgi and Schreiber, Matthias and Krautz, Hans Joachim}, title = {Influence of two- and three-dimensional simulations on bubble behaviorin gas-solid fluidized beds with and without immersed horizontal tubes}, doi = {10.1016/j.powtec.2011.11.050}, language = {en} } @misc{AbangWeissKrautz, author = {Abang, Roger Atini and Weiß, Sabine and Krautz, Hans Joachim}, title = {Impact of increased power plant cycling on the oxidation and corrosion of coal-fired superheater materials}, series = {Fuel}, volume = {2018}, journal = {Fuel}, number = {220}, issn = {0016-2361}, doi = {10.1016/j.fuel.2018.02.047}, pages = {521 -- 534}, abstract = {As power generation from variable renewable energy sources such as wind and solar power continues to increase in the future, fewer baseload power plants will be needed. As a result, high operational flexibility is becoming a vital requirement for conventional power plants to allow for the smooth integration of the variable renewable energy sources (v-RES) into the grid. To understand the impact of high operational flexibility (increased cycling) for coal-fired power plant materials, five commercial coal boiler superheater and reheater materials were investigated under isothermal and cyclic conditions for 1000 h each. The candidate alloys investigated were: T91, VM12-SHC, TP347-HFG, DMV304 HCu and DMV310 N. The results (weight change kinetics and metallographic analysis) after exposure at a metal surface temperature of 650 °C clearly showed the impact of increased flexibility on the corrosion and oxidation of the materials. Oxide growth (weight gain), metal loss, oxide spallation, and grain boundary attack were found to be more severe under cyclic conditions than under isothermal conditions.}, language = {en} } @misc{MerzschLechnerKrautz, author = {Merzsch, Matthias and Lechner, Stefan and Krautz, Hans Joachim}, title = {Heat-transfer from single horizontal tubes in fluidized beds: Influence of tube diameter, moisture and diameter-definition by Geldart C fines content}, series = {Powder Technology}, journal = {Powder Technology}, issn = {1873-328X}, doi = {10.1016/j.powtec.2012.12.002}, language = {en} } @misc{LechnerMerzschKrautz, author = {Lechner, Stefan and Merzsch, Matthias and Krautz, Hans Joachim}, title = {Heat-transfer from horizontal tube bundles into fluidized beds with Geldart A lignite particles}, series = {Powder Technology}, journal = {Powder Technology}, number = {253}, doi = {10.1016/j.powtec.2013.10.041}, pages = {14 -- 21}, abstract = {This work investigates the heat transfer mechanism in fluidized beds equipped with horizontal heat exchanger surfaces such as single tubes and especially tube bundles. Previous works were performed for varying operating conditions and solids' material properties, leading to a heterogeneous and therefore not applicable spectrum of derived correlations for the influence of tube diameter and tube bundle geometry on heat transfer. Based on a wide range validation of the correlation for the influence of single tube diameter on heat transfer coefficient, tube bundles with different tube diameters and horizontal and vertical spacings and alignments were investigated. Experiments were carried out using electrical heat transfer probes in a 0.15 m2 fluidized bed test facility at ambient conditions. Geldart A lignite and Geldart D solids were used in order to distinguish between predominant particle-convective and gas-convective heat transfer mechanisms. The tube bundle reduction factor on heat transfer coefficient was derived as a key parameter based on dimensionless geometric numbers. This factor predicts the reduction of the heat transfer coefficient compared to that of the single tube due to the particle and gas flow disturbances caused by the immersed tubes. Tube diameter as well as tube bundle geometry were successfully implemented into useful correlations for predicting tube bundles' heat transfer of gas-solid fluidized bed systems operating with fine particles.}, language = {en} }