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Stefan K. Henninger - One of the best experts on this subject based on the ideXlab platform.
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evaluation of the highly stable metal organic framework mil 53 al tdc tdc 2 5 thiophenedicarboxylate as a new and promising adsorbent for Heat Transformation applications
Journal of Materials Chemistry, 2018Co-Authors: Niels Tannert, Stefan K. Henninger, Sebastian-johannes Ernst, Christian Jansen, Hans-jörg Bart, Christoph JaniakAbstract:The recently reported Al-based metal–organic framework MIL-53(Al)-TDC (TDC = 2,5-thiophenedicarboxylate) shows desirable water sorption properties towards adsorption-driven Heat Transformation applications with high thermal and solvent/pH stability as well as hydrothermal stability over 40 cycles. Water vapor sorption measurements at 25, 40 and 60 °C yielded an advantageous isosteric Heat of adsorption of only 2.6 kJ g−1, favoring the use of MIL-53(Al)-TDC in sorption based chilling where the released Heat of adsorption corresponds to waste Heat. The good cooling performance of MIL-53(Al)-TDC comes from desirable low desorption temperatures below 65 °C, with also desirable high condenser temperatures of around 40 °C and corresponding water exchange of almost 0.35 g g−1. The thereby offered working window cannot be provided by common adsorbents and renders the material an ideal candidate for adsorption cooling applications.
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Evaluation of the highly stable metal–organic framework MIL-53(Al)-TDC (TDC = 2,5-thiophenedicarboxylate) as a new and promising adsorbent for Heat Transformation applications
Journal of Materials Chemistry A, 2018Co-Authors: Niels Tannert, Stefan K. Henninger, Sebastian-johannes Ernst, Christian Jansen, Hans-jörg Bart, Christoph JaniakAbstract:The recently reported Al-based metal–organic framework MIL-53(Al)-TDC (TDC = 2,5-thiophenedicarboxylate) shows desirable water sorption properties towards adsorption-driven Heat Transformation applications with high thermal and solvent/pH stability as well as hydrothermal stability over 40 cycles. Water vapor sorption measurements at 25, 40 and 60 °C yielded an advantageous isosteric Heat of adsorption of only 2.6 kJ g−1, favoring the use of MIL-53(Al)-TDC in sorption based chilling where the released Heat of adsorption corresponds to waste Heat. The good cooling performance of MIL-53(Al)-TDC comes from desirable low desorption temperatures below 65 °C, with also desirable high condenser temperatures of around 40 °C and corresponding water exchange of almost 0.35 g g−1. The thereby offered working window cannot be provided by common adsorbents and renders the material an ideal candidate for adsorption cooling applications.
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A Functional Full-Scale Heat Exchanger Coated with Aluminum Fumarate Metal–Organic Framework for Adsorption Heat Transformation
Industrial & Engineering Chemistry Research, 2017Co-Authors: Harry Kummer, Dominik Fröhlich, Christoph Janiak, Felix Jeremias, Alexander Warlo, Gerrit Füldner, Roger Gläser, Stefan K. HenningerAbstract:Metal–organic frameworks represent a class of microporous adsorbents with high application potential for adsorption Heat Transformation. Here, we present a functional, full-scale Heat exchanger coated with the microporous aluminum fumarate MOF Basolite A520 using a polysiloxane-based binding agent. The function of the Heat exchanger was evaluated resulting in a gross cooling power of 2900 W (at the beginning of the adsorption cycle) or, respectively an average cooling power of 690 W (up to a limit of 90% equilibrium loading in 7 min) under the working conditions of a realistic adsorption chiller of 90 °C – 30 °C – 18 °C (temperature level of Heat source, Heat rejection/condenser, and evaporator).
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a functional full scale Heat exchanger coated with aluminum fumarate metal organic framework for adsorption Heat Transformation
Industrial & Engineering Chemistry Research, 2017Co-Authors: Harry Kummer, Dominik Fröhlich, Christoph Janiak, Felix Jeremias, Alexander Warlo, Gerrit Füldner, Roger Gläser, Stefan K. HenningerAbstract:Metal–organic frameworks represent a class of microporous adsorbents with high application potential for adsorption Heat Transformation. Here, we present a functional, full-scale Heat exchanger coated with the microporous aluminum fumarate MOF Basolite A520 using a polysiloxane-based binding agent. The function of the Heat exchanger was evaluated resulting in a gross cooling power of 2900 W (at the beginning of the adsorption cycle) or, respectively an average cooling power of 690 W (up to a limit of 90% equilibrium loading in 7 min) under the working conditions of a realistic adsorption chiller of 90 °C – 30 °C – 18 °C (temperature level of Heat source, Heat rejection/condenser, and evaporator).
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Optimization of power density and metal-to-adsorbent weight ratio in coated adsorbers for adsorptive Heat Transformation applications
Applied Thermal Engineering, 2017Co-Authors: Phillip Bendix, Stefan K. Henninger, Marc Möllers, Harry Kummer, Gerrit Füldner, Lena Schnabel, H.-m. HenningAbstract:Abstract Heat Transformation systems such as gas adsorption Heat pumps will be one cornerstone in reducing the carbon footprint of the building sector. Their development calls for an increase in power density without sacrificing energy efficiency. For the adsorber component this translates to small ratio of Heat exchanger to adsorbent mass. Possibilities to achieve this have been investigated on small scale samples as well as on full scale adsorbers. Different samples and adsorbers with varying adsorbent to metal ratios where produced and characterized using the large pressure jump and large temperature jump method. Under certain conditions it could be shown that in small scale and full scale the power can be kept on a high level while increasing the adsorbent to metal ratio. Here the Heat and mass transfer in the coating layer is not limiting the adsorber power.
Christoph Janiak - One of the best experts on this subject based on the ideXlab platform.
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Tunable LiCl@UiO-66 composites for water sorption-based Heat Transformation applications
Journal of Materials Chemistry A, 2020Co-Authors: Yangyang Sun, Sebastian-johannes Ernst, Serkan Gökpinar, Raphael Wiedey, Alex Spieß, Christian Jansen, Alexander Nuhnen, Christoph JaniakAbstract:Porous composite materials are potential candidates for water-based adsorptive Heat Transformation (AHT) applications. Here, a solid adsorbent LiCl@UiO-66 as a 'composite salt inside porous matrix’ (CSPM) has been prepared by incorporating hygroscopic lithium chloride into a microporous metal–organic framework (MOF) UiO-66 as a host matrix through the wet impregnation method. In our wet impregnation we did not let the excess salt solution dry to prevent salt precipitation on the matrix surface. This yielded a true salt@MOF composite with no deliquescence of LiCl and strongly enhanced the water adsorption capacity of UiO-66 through the salt content. At p/p0 = 0.1 the water vapor sorption isotherms show a hydration state of LiCl inside the MOF of LiCl·2–4H2O which is much higher than for neat LiCl with 0.5H2O, due to the dispersion of a small particle size inside the matrix. LiCl@UiO-66 with a 30 wt% LiCl content (LiCl@UiO-66_30) has a 3 to 8 times higher water uptake over neat UiO-66 (depending on relative pressure) and could reach a volumetric and gravimetric water uptake of over 2.15 g g−1 at p/p0 = 0.9, which outperforms the so far known UiO-66-based composites. Cycling tests confirmed the hydrothermal stability of the LiCl@UiO-66 composites. Kinetic evaluation of the gravimetric water uptake (at 90% relative humidity) over time yielded rate coefficients up to 2.0(1) × 10−4 s−1 which is slower than that in neat UiO-66 (6.7(6) × 10−4 s−1) but faster than that for salt@silica gel composites. The coefficient of performance for the Heat pumping mode (at Tdes/Tads/Tevap set to 90/40/10 °C) of 1.64 for LiCl@UiO-66_30 exceeds those of other MOFs, salt@MOF or salt@silica gel composites. For thermal battery applications the Heat storage capacity (CHS) for LiCl@UiO-66_30 is 900 kJ kg−1 (=0.25 kW h kg−1), which can reach the Department of Energy (DOE) value of 2.5 kW h/35 kg with just 10 kg of material and outperforms CaCl2@UiO-66_38 with a CHS value of 367 kJ kg−1.
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Designing a new aluminium muconate metal–organic framework (MIL-53-muc) as a methanol adsorbent for sub-zero temperature Heat Transformation applications
Journal of Materials Chemistry A, 2019Co-Authors: Tobie J. Matemb Ma Ntep, Sebastian-johannes Ernst, Emrah Hastürk, Helge Reinsch, Philipp P. C. Hügenell, Christoph JaniakAbstract:Employing methanol as an adsorbate can enable adsorption-driven Heat pumps and chillers to operate at/or achieve temperatures below 0 °C, provided an appropriate pairing adsorbent is made available. By applying the principle of reticular chemistry, an isoreticular twofold expansion of aluminium fumarate was designed and synthesized using trans,trans-muconate as a linker to a new aluminium metal–organic framework (MOF) termed MIL-53-muc. MIL-53-muc is isostructural to the prototypical aluminium terephthalate (Al-MIL-53-BDC) and is therefore built from chains of trans corner-sharing AlO4(OH)2 octahedra connected by muconate linkers to a microporous network with lozenge-shaped one-dimensional pores. Featuring a high BET specific surface area of 1750 m2 g−1, a type V (S-shaped) stepwise methanol adsorption isotherm in a 0.05–0.15 relative pressure range, a high methanol uptake capacity of about 0.5 g g−1 and methanol stability of over 50 assessed ad/desorption cycles, MIL-53-muc is revealed as a promising adsorbent applicable for adsorption-based Heat Transformation applications. The performance evaluation indicates that high coefficient of performance COPH values above 1.5 could be reached for an evaporator operating at a temperature as low as −5 °C under Heat pump conditions, while very low temperatures down to −10 °C could be achieved for refrigeration/ice making with COPC values of up to 0.73 under cooling conditions. This makes MIL-53-muc/methanol outperform most other working pairs for adsorption-based cooling and Heating applications under sub-zero temperature conditions. Furthermore, MIL-53-muc is hydrothermally stable and presents a favorable water sorption profile making this material also suitable for autonomous indoor humidity control applications.
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Recent advances in adsorption Heat Transformation focusing on the development of adsorbent materials
Current Opinion in Chemical Engineering, 2019Co-Authors: Emrah Hastürk, Sebastian-johannes Ernst, Christoph JaniakAbstract:Adsorption Heat Transformation (AHT) is an environmentally friendly energy-saving process applied for air conditioning purposes, that is, either for cooling (including also ice making and refrigeration), or Heating. AHT is based on the cycling adsorption and desorption of a working fluid in a porous material. When the working fluid is driven to evaporation by the active empty sorbent material, the required Heat of evaporation translates into useful cooling in thermally driven adsorption chillers. Driving Heat regenerates the empty sorbent material through desorption of the working fluid. The Heat of adsorption in the sorbent material and the Heat of condensation of the working fluid can be used in the adsorption Heat-pumping mode. Thus, adsorption Heat Transformation contributes to energy-saving technologies. Adsorbent development plays a critical role for the improvement of AHT technologies. Besides silica gel and zeolites as adsorbent materials, which are up to now used in the commercially available AHT devices; especially metal-organic frameworks (MOFs) are getting more attentions in recent years. Composite materials from salts with silica gels, zeolites and MOFs as well as activated carbons have also been researched to contribute to AHT technologies. Reduction of installation/production cost and enhancement of the efficiency of AHT devices need to be achieved to increase the wider usage of AHT.
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evaluation of the highly stable metal organic framework mil 53 al tdc tdc 2 5 thiophenedicarboxylate as a new and promising adsorbent for Heat Transformation applications
Journal of Materials Chemistry, 2018Co-Authors: Niels Tannert, Stefan K. Henninger, Sebastian-johannes Ernst, Christian Jansen, Hans-jörg Bart, Christoph JaniakAbstract:The recently reported Al-based metal–organic framework MIL-53(Al)-TDC (TDC = 2,5-thiophenedicarboxylate) shows desirable water sorption properties towards adsorption-driven Heat Transformation applications with high thermal and solvent/pH stability as well as hydrothermal stability over 40 cycles. Water vapor sorption measurements at 25, 40 and 60 °C yielded an advantageous isosteric Heat of adsorption of only 2.6 kJ g−1, favoring the use of MIL-53(Al)-TDC in sorption based chilling where the released Heat of adsorption corresponds to waste Heat. The good cooling performance of MIL-53(Al)-TDC comes from desirable low desorption temperatures below 65 °C, with also desirable high condenser temperatures of around 40 °C and corresponding water exchange of almost 0.35 g g−1. The thereby offered working window cannot be provided by common adsorbents and renders the material an ideal candidate for adsorption cooling applications.
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Evaluation of the highly stable metal–organic framework MIL-53(Al)-TDC (TDC = 2,5-thiophenedicarboxylate) as a new and promising adsorbent for Heat Transformation applications
Journal of Materials Chemistry A, 2018Co-Authors: Niels Tannert, Stefan K. Henninger, Sebastian-johannes Ernst, Christian Jansen, Hans-jörg Bart, Christoph JaniakAbstract:The recently reported Al-based metal–organic framework MIL-53(Al)-TDC (TDC = 2,5-thiophenedicarboxylate) shows desirable water sorption properties towards adsorption-driven Heat Transformation applications with high thermal and solvent/pH stability as well as hydrothermal stability over 40 cycles. Water vapor sorption measurements at 25, 40 and 60 °C yielded an advantageous isosteric Heat of adsorption of only 2.6 kJ g−1, favoring the use of MIL-53(Al)-TDC in sorption based chilling where the released Heat of adsorption corresponds to waste Heat. The good cooling performance of MIL-53(Al)-TDC comes from desirable low desorption temperatures below 65 °C, with also desirable high condenser temperatures of around 40 °C and corresponding water exchange of almost 0.35 g g−1. The thereby offered working window cannot be provided by common adsorbents and renders the material an ideal candidate for adsorption cooling applications.
H.-m. Henning - One of the best experts on this subject based on the ideXlab platform.
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Optimization of power density and metal-to-adsorbent weight ratio in coated adsorbers for adsorptive Heat Transformation applications
Applied Thermal Engineering, 2017Co-Authors: Phillip Bendix, Stefan K. Henninger, Marc Möllers, Harry Kummer, Gerrit Füldner, Lena Schnabel, H.-m. HenningAbstract:Abstract Heat Transformation systems such as gas adsorption Heat pumps will be one cornerstone in reducing the carbon footprint of the building sector. Their development calls for an increase in power density without sacrificing energy efficiency. For the adsorber component this translates to small ratio of Heat exchanger to adsorbent mass. Possibilities to achieve this have been investigated on small scale samples as well as on full scale adsorbers. Different samples and adsorbers with varying adsorbent to metal ratios where produced and characterized using the large pressure jump and large temperature jump method. Under certain conditions it could be shown that in small scale and full scale the power can be kept on a high level while increasing the adsorbent to metal ratio. Here the Heat and mass transfer in the coating layer is not limiting the adsorber power.
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Characterisation and improvement of sorption materials with molecular modeling for the use in Heat Transformation applications
Adsorption, 2011Co-Authors: S. K. Henninger, F. P. Schmidt, H.-m. HenningAbstract:In this paper, several materials for sorption Heat Transformation applications are evaluated on basis of experimental characterisation and molecular simulation methods. With regard to the application, classical zeolites, ion exchanged zeolites, aluminophosphates as well as silica-aluminophosphates have been analysed. Furthermore samples of metal organic frameworks (MOF) have been evaluated for the use in sorption Heat Transformation applications with very promising results. In order to understand the fundamental relationship between adsorbent microstructure and water adsorption equilibrium, molecular simulation of water adsorption in various adsorbents are employed. As a result of these simulations within the grand canonical ensemble, the number of water molecules adsorbed in thermodynamic equilibrium under given conditions of temperature and chemical potential (resp. pressure) are obtained. These data are compared with adsorption data from thermogravimetric measurements.
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Characterisation and improvement of sorption materials with molecular modeling for the use in Heat Transformation applications
Adsorption, 2011Co-Authors: Stefan K. Henninger, Ferdinand Schmidt, H.-m. HenningAbstract:In this paper, several materials for sorption Heat Transformation applications are evaluated on basis of experimental characterisation and molecular simulation methods. With regard to the application, classical zeolites, ion exchanged zeolites, aluminophosphates as well as silica-aluminophosphates have been analysed. Furthermore samples of metal organic frameworks (MOF) have been evaluated for the use in sorption Heat Transformation applications with very promising results. In order to understand the fundamental relationship between adsorbent microstructure and water adsorption equilibrium, molecular simulation of water adsorption in various adsorbents are employed. As a result of these simulations within the grand canonical ensemble, the number of water molecules adsorbed in thermodynamic equilibrium under given conditions of temperature and chemical potential (resp. pressure) are obtained. These data are compared with adsorption data from thermogravimetric measurements.
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Water adsorption characteristics of novel materials for Heat Transformation applications
Applied Thermal Engineering, 2010Co-Authors: Stefan K. Henninger, Ferdinand Schmidt, H.-m. HenningAbstract:Abstract Within this article we illustrate recent development of sorption materials for Heat Transformation applications. A broad overview on the possible performance of currently available and recently developed materials ranging from zeolites across aluminophosphates and silicoaluminophosphates to the novel class of metal organic framework materials is given. Materials are evaluated with respect to the use in thermal driven adsorptive Heat pumping and cooling applications with water as refrigerant. Therefore a new fingerprinting method is used to evaluate samples under two typical cycle conditions with driving temperatures of 95 °C and 140 °C. A unique aspect is that results can be used for closed as well as for open adsorptive systems. The highest water uptake for driving temperatures of 95 °C was found for an AlPO-18 with 0.253 g/g, which is more than six times higher than the reference silica gel in our comparison. For driving temperatures of 140 °C the highest water uptake was found for the metal organic framework Cu-BTC with 0.324 g/g. Furthermore we give first results on the integral Heat of adsorption in the cycle and results of hydrothermal treatment of most promising materials.
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development of an adsorption chiller and Heat pump for domestic Heating and air conditioning applications
Applied Thermal Engineering, 2007Co-Authors: Tomas Nunez, Walter Mittelbach, H.-m. HenningAbstract:Abstract The scope of this paper is to present the development of a prototype of a small adsorption Heat pump working on the adsorption pair silica gel–water. The development of this prototype with remarkable high power densities has been carried out during the last year and is a result of continued joint work on adsorption Heat Transformation systems carried out at SorTech AG and the Fraunhofer Institute.
Marc Linder - One of the best experts on this subject based on the ideXlab platform.
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Thermodynamic and kinetic investigations of the SrBr2 hydration and dehydration reactions for thermochemical energy storage and Heat Transformation
Applied Energy, 2020Co-Authors: Jana Stengler, Inga Bürger, Marc LinderAbstract:Abstract The potential of thermochemical energy storage and Heat Transformation has been soundly highlighted in literature. For applications in the temperature range from approximately 150 °C to 300 °C, the inorganic salt strontium bromide, which reacts with water vapor in an exothermic reaction, is a promising candidate: SrBr2 (s) + H2O (g) ⇌ SrBr2·H2O (s) + ΔRH. This chemical reaction offers a specific energy density of 291 kJ/kg SrBr2 (or 81 kWh/t). The feasibility of a thermochemical energy storage and Heat transformer based on the SrBr2/H2O working pair has already been successfully demonstrated on a 1 kW scale in a lab-scale storage unit. Here, we report on the steam pressure-dependent reaction temperatures of the dehydration and hydration reactions as well as the reaction rate and the cycle stability of the reactive system over 100 reaction cycles using thermogravimetric analysis. For distinct operating points, e.g. running the hydration reaction at 180 °C and 69 kPa, specific thermal powers up to 4 kW/kg SrBr2 were experimentally determined. Running the dehydration reaction at 210 °C and 5 kPa steam pressure showed specific thermal powers of 2.5 kW/kg of SrBr2·H2O, thus proving the suitability of SrBr2/H2O as thermochemical working pair for high-power storage applications. Our results provide fundamental material-related data for the design of high-power reactor modules as well as for numerical studies on the potential of thermochemical energy storage and Heat Transformation based on SrBr2/H2O.
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Analysis of a Lab-Scale Heat Transformation Demonstrator Based on a Gas–Solid Reaction
Energies, 2019Co-Authors: Jana Stengler, Julius Weiss, Marc LinderAbstract:Heat Transformation based on reversible chemical reactions has gained significant interest due to the high achievable output temperatures. This specific type of chemical Heat pump uses a reversible gas–solid reaction, with the back and forward reactions taking place at different temperatures: by running the exothermic discharge reaction at a higher temperature than the endothermic charge reaction, the released Heat is thermally upgraded. In this work, we report on the experimental investigation of the hydration reaction of strontium bromide (SrBr 2 ) with regard to its use for Heat Transformation in the temperature range from 180 °C to 250 °C on a 1 kg scale. The reaction temperature is set by adjusting the pressure of the gaseous reactant. In previous experimental studies, we found the macroscopic and microscopic properties of the solid bulk phase to be subject to considerable changes due to the chemical reaction-. In order to better understand how this affects the thermal discharge performance of a thermochemical reactor, we combine our experimental work with a modelling approach. From the results of the presented studies, we derive design rules and operating parameters for a thermochemical storage module based on SrBr 2 .
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High temperature thermochemical Heat Transformation based on SrBr2
2017Co-Authors: Jana Stengler, Torsten Ascher, Marc LinderAbstract:Currently, state of the art working fluids of conventional Heat pumps are limited to maximum output temperatures of 140 °C, and thus cannot fulfill the need for high temperature Heat pumps in industrial applications. This is why thermochemical reaction systems have come into the focus of interest: they offer the potential of high temperature energy storage and Heat Transformation, e.g. by making use of the pressure dependency of a gas-solid reaction. These reactions can in general be described by the following equation: A(s) + B(g) ⇌ AB(s) + ΔRH. Variation of the pressure of the gaseous reactant B results in a temperature shift of the exothermic reaction. In this way, the exothermic reaction (energy output) can be performed at higher temperatures than the endothermic reaction (energy input). In this contribution, the thermodynamic principle of thermally driven Heat Transformation and its main difference with respect to conventional or sorption based Heat pumps is outlined. The scope of this work is the potential of the SrBr2–H2O system as a possible candidate for thermochemical Heat Transformation. Constraints for a suitable reactor geometry and the possibility to combine thermal upgrade and thermal energy storage into one system are analyzed. Experimental results from a laboratory scale test reactor (~ 1,000 g) support the proof of concept of Heat Transformation in the region of 200 °C.
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Waste Heat Driven Thermochemical Heat Transformationbased on a Salt Hydrate
2017Co-Authors: Jana Stengler, Marius Drexler, Marc LinderAbstract:In the course of efforts to reduce primary energy consumption in chemical process industries, recovery of low enthalpy energy sources such as low temperature waste Heat has come into the focus of interest. However, there is no Heat pump commercially available yet that offers an output temperature of more than 140 °C, which is a minimum temperature required for many industrial applications. In this regard, thermochemical Heat Transformation based on gas-solid reactions can be used to generate a high temperature Heat pump-like effect. The reversible reaction of strontium bromide with water vapor is proposed in this work for thermochemical Heat Transformation: SrBr2(s) + H2O(g) ⇌ SrBr2 x H2O(s) + ΔRH. Driven by 90 °C waste Heat, this chemical reaction offers the possibility to “lift” process Heat flows to a higher temperature level in the range of 180 °C to 230 °C. By variation of the partial pressure of water vapor, the equilibrium temperatures of the both the hydration and dehydration reaction can be controlled. Consequently, it is possible to conduct the exothermic reaction at a higher temperature than the endothermic reaction. Process Heat which is stored in the form of chemical potential during the dehydration reaction can afterwards be recovered at a higher temperature during the hydration reaction. In the proposed process, water vapor supply is covered by low temperature waste Heat. The resulting thermal upgrade of process Heat allows to cut down on additional Heating and thus leads to a reduced consumption of primary energy resources. The oral contribution will outline the thermodynamic principle of thermally driven Heat Transformation and its main difference to conventional Heat pumps. In addition, the potential of the reactant couple SrBr2/H2O will be discussed based on experimental results from a lab-scale reactor setup.
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Thermochemical energy storage and Heat Transformation based on SrBr2: generic reactor concept for validation experiments
2016Co-Authors: Jana Stengler, Margarethe Richter, Marc LinderAbstract:Since energy efficiency of chemical processes becomes more and more important, recovery of thermal waste Heat offers an increasing potential for industrial applications. In general, re-integrating waste Heat into a chemical process not solely depends on the simultaneous presence of availability and demand. It is also limited by the temperature level of the Heat flows, as waste Heat flows usually occur at lower temperatures than the actual required process Heat. A Heat pump could principally be used to close this temperature gap. However, there is no Heat pump commercially available yet that offers output temperatures of more than 140 °C [1]. Therefore, thermochemical energy storage based on gas-solid reactions has come into the focus of interest [2]. Such reactions can generally be described by the following reaction equation: A(s) + B(g) AB(s) + ΔRH. By varying the partial pressure of the gaseous reaction partner B, the required reaction temperature can be adjusted. Thereby, it is possible to perform the endothermic reaction at lower temperatures than the exothermic reaction, and hence achieve a temperature lift between energy input and energy output. Additionally, gas-solid reactions can also be used for storing thermal energy with high storage densities, which makes them very attractive candidates for waste Heat recovery. In this work, SrBr2/H2O has been chosen as a working pair of materials. The reversible reaction of SrBr2 monohydrate to the hydrate SrBr2 x 6 H2O has been applied for thermochemical energy storage for domestic use below 80 °C [3, 4]. However, by using a different reaction step, namely a lower degree of hydration, energy storage as well as Heat Transformation at temperatures relevant for industrial waste Heat recovery (150 – 300 °C) seems thermodynamically possible. In order to investigate the application potential of this reaction, it was analyzed considering technically relevant boundary conditions. In the oral presentation, a comparison of experimental thermodynamic and kinetic data at two mass scales will be discussed: on the one hand, 15 mg SrBr2 monohydrate were tested using thermogravimetric analysis. On the other hand, 1 kg of the solid was analyzed in a lab-scale reactor which was mainly designed to obtain experimental data, e.g. for model validations. Due to its generic geometry, it allows to test the effects of various process parameters, such as pressure variations or different gas in- and outlet conditions, on the performance of the reactive bulk. This consequently leads to a deeper understanding of material requirements for the applications mentioned above, since thermodynamic and kinetic limitations of the reactive material can be properly distinguished from macroscopic effects, e.g. the effects of Heat and mass transfer within its bulk. References: [1] REISSNER, F.; GROMOLL, B.; SCHAEFER, J.; DANOV, V.; KARL, J. Experimental performance evaluation of new safe and environmentally friendly working fluids for high temperature Heat pumps. European Heat Pump Summit, Nurnberg, Germany, October 2013. [2] YU, Y.Q.; ZHANG, P.; WU, J.Y.; WANG, R.Z. Energy upgrading by solid-gas reaction Heat transformer: A critical review. Renewable and Sustainable Energy Reviews, 2008, Volume 12, 1302-1324. [3] LELE, A.F.; KUZNIK, F.; OPEL, O.; RUCK, W.K.L. Performance analysis of a thermochemical based Heat storage as an addition to cogeneration systems. Energy Conversion and Management, 2015, Volume 106, 1327–1344. [4] MICHEL, B.; MAZET, N.; NEVEU, P. Experimental investigation of an innovative thermochemical process operating with a hydrate salt and moist air for thermal storage of solar energy: Global performance. Applied Energy, 2014, Volume 129, 177-186.
Sebastian-johannes Ernst - One of the best experts on this subject based on the ideXlab platform.
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Tunable LiCl@UiO-66 composites for water sorption-based Heat Transformation applications
Journal of Materials Chemistry A, 2020Co-Authors: Yangyang Sun, Sebastian-johannes Ernst, Serkan Gökpinar, Raphael Wiedey, Alex Spieß, Christian Jansen, Alexander Nuhnen, Christoph JaniakAbstract:Porous composite materials are potential candidates for water-based adsorptive Heat Transformation (AHT) applications. Here, a solid adsorbent LiCl@UiO-66 as a 'composite salt inside porous matrix’ (CSPM) has been prepared by incorporating hygroscopic lithium chloride into a microporous metal–organic framework (MOF) UiO-66 as a host matrix through the wet impregnation method. In our wet impregnation we did not let the excess salt solution dry to prevent salt precipitation on the matrix surface. This yielded a true salt@MOF composite with no deliquescence of LiCl and strongly enhanced the water adsorption capacity of UiO-66 through the salt content. At p/p0 = 0.1 the water vapor sorption isotherms show a hydration state of LiCl inside the MOF of LiCl·2–4H2O which is much higher than for neat LiCl with 0.5H2O, due to the dispersion of a small particle size inside the matrix. LiCl@UiO-66 with a 30 wt% LiCl content (LiCl@UiO-66_30) has a 3 to 8 times higher water uptake over neat UiO-66 (depending on relative pressure) and could reach a volumetric and gravimetric water uptake of over 2.15 g g−1 at p/p0 = 0.9, which outperforms the so far known UiO-66-based composites. Cycling tests confirmed the hydrothermal stability of the LiCl@UiO-66 composites. Kinetic evaluation of the gravimetric water uptake (at 90% relative humidity) over time yielded rate coefficients up to 2.0(1) × 10−4 s−1 which is slower than that in neat UiO-66 (6.7(6) × 10−4 s−1) but faster than that for salt@silica gel composites. The coefficient of performance for the Heat pumping mode (at Tdes/Tads/Tevap set to 90/40/10 °C) of 1.64 for LiCl@UiO-66_30 exceeds those of other MOFs, salt@MOF or salt@silica gel composites. For thermal battery applications the Heat storage capacity (CHS) for LiCl@UiO-66_30 is 900 kJ kg−1 (=0.25 kW h kg−1), which can reach the Department of Energy (DOE) value of 2.5 kW h/35 kg with just 10 kg of material and outperforms CaCl2@UiO-66_38 with a CHS value of 367 kJ kg−1.
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Designing a new aluminium muconate metal–organic framework (MIL-53-muc) as a methanol adsorbent for sub-zero temperature Heat Transformation applications
Journal of Materials Chemistry A, 2019Co-Authors: Tobie J. Matemb Ma Ntep, Sebastian-johannes Ernst, Emrah Hastürk, Helge Reinsch, Philipp P. C. Hügenell, Christoph JaniakAbstract:Employing methanol as an adsorbate can enable adsorption-driven Heat pumps and chillers to operate at/or achieve temperatures below 0 °C, provided an appropriate pairing adsorbent is made available. By applying the principle of reticular chemistry, an isoreticular twofold expansion of aluminium fumarate was designed and synthesized using trans,trans-muconate as a linker to a new aluminium metal–organic framework (MOF) termed MIL-53-muc. MIL-53-muc is isostructural to the prototypical aluminium terephthalate (Al-MIL-53-BDC) and is therefore built from chains of trans corner-sharing AlO4(OH)2 octahedra connected by muconate linkers to a microporous network with lozenge-shaped one-dimensional pores. Featuring a high BET specific surface area of 1750 m2 g−1, a type V (S-shaped) stepwise methanol adsorption isotherm in a 0.05–0.15 relative pressure range, a high methanol uptake capacity of about 0.5 g g−1 and methanol stability of over 50 assessed ad/desorption cycles, MIL-53-muc is revealed as a promising adsorbent applicable for adsorption-based Heat Transformation applications. The performance evaluation indicates that high coefficient of performance COPH values above 1.5 could be reached for an evaporator operating at a temperature as low as −5 °C under Heat pump conditions, while very low temperatures down to −10 °C could be achieved for refrigeration/ice making with COPC values of up to 0.73 under cooling conditions. This makes MIL-53-muc/methanol outperform most other working pairs for adsorption-based cooling and Heating applications under sub-zero temperature conditions. Furthermore, MIL-53-muc is hydrothermally stable and presents a favorable water sorption profile making this material also suitable for autonomous indoor humidity control applications.
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Air-Con Metal–Organic Frameworks in Binder Composites for Water Adsorption Heat Transformation Systems
Industrial & Engineering Chemistry Research, 2019Co-Authors: Serkan Gökpinar, Sebastian-johannes Ernst, Emrah Hastürk, Marc Möllers, Ilias El Aita, Raphael Wiedey, Niels Tannert, Sandra Nießing, Soheil Abdpour, Alexa SchmitzAbstract:Metal–organic frameworks (MOFs) currently receive high interest for cycling water adsorption applications like adsorption Heat Transformation for air-conditioning purposes. For practical use in ads...
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Recent advances in adsorption Heat Transformation focusing on the development of adsorbent materials
Current Opinion in Chemical Engineering, 2019Co-Authors: Emrah Hastürk, Sebastian-johannes Ernst, Christoph JaniakAbstract:Adsorption Heat Transformation (AHT) is an environmentally friendly energy-saving process applied for air conditioning purposes, that is, either for cooling (including also ice making and refrigeration), or Heating. AHT is based on the cycling adsorption and desorption of a working fluid in a porous material. When the working fluid is driven to evaporation by the active empty sorbent material, the required Heat of evaporation translates into useful cooling in thermally driven adsorption chillers. Driving Heat regenerates the empty sorbent material through desorption of the working fluid. The Heat of adsorption in the sorbent material and the Heat of condensation of the working fluid can be used in the adsorption Heat-pumping mode. Thus, adsorption Heat Transformation contributes to energy-saving technologies. Adsorbent development plays a critical role for the improvement of AHT technologies. Besides silica gel and zeolites as adsorbent materials, which are up to now used in the commercially available AHT devices; especially metal-organic frameworks (MOFs) are getting more attentions in recent years. Composite materials from salts with silica gels, zeolites and MOFs as well as activated carbons have also been researched to contribute to AHT technologies. Reduction of installation/production cost and enhancement of the efficiency of AHT devices need to be achieved to increase the wider usage of AHT.
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evaluation of the highly stable metal organic framework mil 53 al tdc tdc 2 5 thiophenedicarboxylate as a new and promising adsorbent for Heat Transformation applications
Journal of Materials Chemistry, 2018Co-Authors: Niels Tannert, Stefan K. Henninger, Sebastian-johannes Ernst, Christian Jansen, Hans-jörg Bart, Christoph JaniakAbstract:The recently reported Al-based metal–organic framework MIL-53(Al)-TDC (TDC = 2,5-thiophenedicarboxylate) shows desirable water sorption properties towards adsorption-driven Heat Transformation applications with high thermal and solvent/pH stability as well as hydrothermal stability over 40 cycles. Water vapor sorption measurements at 25, 40 and 60 °C yielded an advantageous isosteric Heat of adsorption of only 2.6 kJ g−1, favoring the use of MIL-53(Al)-TDC in sorption based chilling where the released Heat of adsorption corresponds to waste Heat. The good cooling performance of MIL-53(Al)-TDC comes from desirable low desorption temperatures below 65 °C, with also desirable high condenser temperatures of around 40 °C and corresponding water exchange of almost 0.35 g g−1. The thereby offered working window cannot be provided by common adsorbents and renders the material an ideal candidate for adsorption cooling applications.