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1
Weaver, R. C. "A fibre-optic microcalorimeter for studying interactions of gases with thin film sensor materials." Thesis, University of Kent, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233913.
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Lione, Richard. "The study of heats of adsorption of gases of thin organic films using a novel interferometric micro-calorimeter." Thesis, University of Kent, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358168.
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Starr, David E. "Microcalorimetric heats of adsorption, surface residence times and sticking probabilities of metals on metal-oxide, and silicon substrates /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/8492.
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Darga, Alexander. "Sorption isotherms of volatile molecules on micro- and mesoporous nanosized siliceous materials based on acoustic wave devices : Determination of corresponding isosteric heats of adsorption." kostenfrei, 2008. http://edoc.ub.uni-muenchen.de/9093/.
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Cairns, Amy J. "Structural Diversity in Crystal Chemistry: Rational Design Strategies Toward the Synthesis of Functional Metal-Organic Materials." Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3455.
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Metal-Organic Materials (MOMs) represent an important class of solid-state crystalline materials. Their countless attractive attributes make them uniquely suited to potentially resolve many present and future utilitarian societal challenges ranging from energy and the environment, all the way to include biology and medicine. Since the birth of coordination chemistry, the self-assembly of organic molecules with metal ions has produced a plethora of simple and complex architectures, many of which possess diverse pore and channel systems in a periodic array. In its infancy however this field was primarily fueled by burgeoning serendipitous discoveries, with no regard to a rational design approach to synthesis.
In the late 1980s, the field was transformed when the potential for design was introduced through the seminal studies conducted by Hoskins and Robson who transcended the pivotal works of Wells into the experimental regime. The construction of MOMs using metal-ligand directed assembly is often regarded as the origin of the molecular building block (MBB) approach, a rational design strategy that focuses on the self-assembly of pre-designed MBBs having desired shapes and geometries to generate structures with intended topologies by exploiting the diverse coordination modes and geometries afforded by metal ions and organic molecules.
The evolution of the MBB approach has witnessed tremendous breakthroughs in terms of scale and porosity by simply replacing single metal ions with more rigid inorganic metal clusters whilst preserving the inherent modularity and essential geometrical attributes needed to construct target networks for desired applications. The work presented in this dissertation focuses upon the rational design and synthesis of a diverse collection of open frameworks constructed from pre-fabricated rigid inorganic MBBs (i.e. [M(CO2)4], [M2(RCO2)4], [M3O(RCO2)6], MN3O3, etc), supermolecular building blocks (SBBs) and 3-, 4- and 6-connected organic MBBs. A systematic evaluation concerning the effect of various structural parameters (i.e. pore size and shape, metal ion, charge, etc) on hydrogen uptake and the relative binding affinity of H2-MOF interactions for selected systems is provided.
6
Robbins, Thomas. "Small-scale heat-driven adsorption cooling." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/52982.
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Heat driven adsorption cycles use heat sources ranging in temperature from 80 - 150 °C to provide cooling, and have been used in both air conditioning and refrigeration applications. Adsorbent heat pumps operate with low cost, simple components, and very little vibration, making them appealing as an alternative heat pump technology. However, they have been limited thus far to commercial and industrial scale applications. To date, adsorption systems have predominantly used natural or industrial waste streams as heat sources in the 10s of kW range. This work expands the scope of adsorption applications to include heat driven cooling at small capacities (watts) and mobile cooling without electronic controls. Autonomous heat driven adsorption system controls are proposed and tested for these systems. Component and system level models are developed for design and assessment. Major trends in system performance with scale are identified and the causes for these scaling effects are presented. New adsorbent bed designs are proposed and modeled for small-scale adsorption systems. The small-scale adsorbent bed designs are fabricated and tested. Models are validated and refined based on the experimental results. Through a combination of modeling and experimental results, this work demonstrates the feasibility of adsorption system application at capacities that two orders of magnitude lower than any previously demonstrated work.
7
Metcalf, Steven John. "Compact, efficient carbon-ammonia adsorption heat pump." Thesis, University of Warwick, 2009. http://wrap.warwick.ac.uk/2777/.
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The modelling, design, construction and experimental testing of a carbon-ammonia adsorption heat pump is presented. The main objective of the research was to design, manufacture and test an adsorption generator with low thermal mass and high power density. The adsorption generator developed was a stainless steel, nickel brazed plate heat exchanger. Computational modelling of the generator with thermal wave and multiplebed cycles revealed that multiple-bed cycles give a superior trade-off between efficiency and power density. Further modelling was carried out to evaluate the performance of the adsorption generator in a four-bed gas-fired domestic heat pump system. The proposed system is air-source and could deliver a nominal heating power of 7 kW and a seasonal heating COP of 1.35, equivalent to a one third reduction in gas consumption in comparison to a condensing boiler. The systems performance was compared to a vapour compression heat pump on running costs and CO2 emissions and was found to be similar or better in all cases. The adsorption generator was tested in a two-bed air-source heat pump system and achieved heating powers from 7 to 11 kW and a heating COP of between 1.4 and 1.6. Specific heating power ranged from 3.9 kW kg-1 to 6.1 kW kg-1, equivalent to specific cooling powers of between 1.1 kW kg-1 and 2 kW kg-1, which is a significant increase in power density compared to the state of the art.
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Rivero, Pacho Ángeles María. "Thermodynamic and heat transfer analysis of a carbon-ammonia adsorption heat pump." Thesis, University of Warwick, 2014. http://wrap.warwick.ac.uk/66341/.
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The modelling, design, construction and experimental testing of a carbon-ammonia adsorption heat pump is presented. The main objective of the research was to computer simulate and test a 4-beds thermal wave adsorption cycle and to improve the heat transfer rate in an existing shell and tube generator. The existing generators were shell and tube type and were made of nickel brazed stainless steel but their heat transfer performance was poor. New heat exchangers with same design but larger in size were manufactured. The sorbent material, active carbon, was tested in order to characterise its thermal properties and a new generator filling technique was developed and presented. Computational modelling was carried out to evaluate the performance of the 4-beds thermal wave adsorption cycle. The proposed system was an air source heat pump that could deliver an output heating power of 7 kW and a seasonal heating COP of 1.47. The adsorption generators were tested in a 4-bed thermal wave air-source heat pump system and achieved heating output powers between 4.5 to 5.20 kW if taking into account the system heat losses (4.30 to 4.90 kW without heat losses) and heating COP’s of between 1.26 and 1.31 if taking into account the system heat losses (1.13 to 1.18 kW without heat losses). These values were significantly lower than the predicted performance of the simulation. The main cause of this discrepancy was the water distributors located at the end of the generators that distorted during the testing stage and blocked the tubes of the generators.
9
Schawe, Dirk. "Theoretical and experimental investigations of an adsorption heat pump with heat transfer between two adsorbers." [S.l. : s.n.], 2001. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB8962132.
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Fuller, Timothy Alan. "An analytical study of the performance characteristics of solid/vapor adsorption heat pumps." Thesis, Georgia Institute of Technology, 1990. http://hdl.handle.net/1853/16961.
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Ajo, Henry. "Energetics of hydrocarbon adsorption on model catalysts /." Thesis, Connect to this title online; UW restricted, 2003. http://hdl.handle.net/1773/8486.
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Splith, Tobias, Christian Chmelik, Frank Stallmach, et al. "Adsorptive heat transformation with SAPO-34." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-198701.
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Ellis, Michael Wayne. "An evaluation of the effect of adsorbent properties on the performance of a solid sorption heat pump." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/17835.
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Yurtsever, Ahmet Onur. "Mathematical Modeling Of Adsorption/desorption Systems For Chemical Heat Pumps." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12612917/index.pdf.
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Despite their limited commercial applications, chemical heat pumps (CHP)
have been considered as an important alternative to conventional heating
and cooling technologies. In this study, the adsorption-desorption of
ethanol over activated carbon was applied on the CHP reactor. The
ethanol vapor - activated carbon adsorption rate was determined at 30,
60, 90 and 120°<br>experimentally by using Intelligent Gravimetric Analyzer
C(IGA). The experimental adsorption data were used on the transient
modeling of reactor by assuming single component gas phase. Then,
spatial and temporal temperature, rate of heat transfer, and total amount
of heat transferred for a given period were determined. Finally, the
calculated adsorption and temperature profiles were integrated over
volume to predict performance of heat pump for different reactor
geometries. The results showed that, with proper modeling satisfactory
performance values can be attained using these systems.
15
Banjara, Shree Ram. "STUDY OF ADSORPTION OF CARBON DIOXIDE ON CARBON BASED NANO-MATERIALS AND EVALUATION OF ISOSTERIC HEAT, SPECIFIC EFFECTIVE SURFACE AREA AVAILABLE FOR ADSORPTION AND ADSORPTION KINETICS." OpenSIUC, 2012. https://opensiuc.lib.siu.edu/theses/915.
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Single-walled dahlia-like carbon nanohorns treated with H2O2 for 3hrs at 150 ℃ were used as sorbent in a study of CO2 adsorption. This treatment ensures that the nanohorns are open and they have their interior space available for adsorption. Volumetric adsorption measurements on open spherical aggregates of dahlia-like single walled carbon nanohorns were performed at seven different temperatures between 158.66 K and 208.68 K. The waiting time for reaching the equilibrium pressure after adding a dose increased with sorbent loading. Unlike Ne and CF4 adsorption isotherms measured on similar substrate which have two distinct substeps present in the isotherms, the adsorption data for CO2 has a single very broad step present between the lowest coverage and saturation. Results for the loading dependence of the isosteric heat indicate that this quantity depends non-monotonically on the amount of CO2 adsorbed. The effective specific surface area of the open single walled carbon nanohorns sample obtained in this study are compared with the ones obtained with other carbon nanohorn samples; the results clearly indicate that nanohorns are open.
16
GENTILE, VINCENZO MARIA. "Innovative Adsorption Heat Exchangers for Desiccant Cooling and Atmospheric Water Harvesting." Doctoral thesis, Politecnico di Torino, 2020. http://hdl.handle.net/11583/2861334.
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Li, Yong, and 李勇. "Performance prediction model for a rotary multi-bed adsorption coolingsystem." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B31245742.
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Khaliji, Oskouei Mohammadhasan. "Thermodynamic and heat transfer analysis of an activated carbon-R723 adsorption system." Thesis, University of Warwick, 2016. http://wrap.warwick.ac.uk/95081/.
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The main challenge of adsorption systems today is to improve the performance of the thermal generator in order to make adsorption systems economically viable. The key novelty of this doctoral thesis is its evaluation of the potential use of a new refrigerant, R723, in an adsorption system using activated carbon as adsorbent. Granular activated carbon is a well-known and effective adsorbent in adsorption systems. The R723 refrigerant was introduced into the market in early 2004; this new refrigerant is an azeotropic mixture of 40% ammonia and 60% dimethyl ether by mass. The new refrigerant is compatible with copper alloy (Cu-Ni 90/10), in comparison with ammonia, which is only compatible with stainless steel. The high thermal conductivity of Cu-Ni 90/10 causes an improvement in heat exchange in the thermal generator. This work investigates the effect of granular activated carbon packed bed density on gas permeability. A correlation was found between granular activated carbon packing density and refrigerant pressure drop over the thermal generator. The porosity of granular activated carbon in terms of adsorbing the R723 was determined. The porosity was evaluated using the gas mixture adsorption theory and using the porosity experimental data for granular activated carbon / ammonia and granular activated carbon / dimethyl ether pairs. The performance of the adsorption system for different applications was determined with the activated carbon / R723 pair. The effects of concentration of R723 and granular activated carbon packing density on the thermal parameters of activated carbon packing, including the thermal conductivity and heat transfer coefficients of the contact wall/packed carbon, were studied simultaneously. A correlation was established showing the connection between the thermal parameters of the packed bed, and the concentration of R723 and the density of the granular activated carbon packed bed. Finally, this thesis demonstrates modelling procedures for a tubular generator with the granular activated carbon (208-C) / R723 pair, with regard to different applications such as air conditioning, ice making and a heat pump. The model under consideration included the ideal desorption effect without heat and mass recovery, while imposing the ideal temperature jump into the boundary of the tubular generator. During the modelling, information such as driving temperature (Tg), coefficient of performance (COP), and specific cooling and heating powers (SCP & SHP), was collected. The collected information was used to established a correlation in order to estimate the optimum driving temperature, COP, SHP and SCP, based on different governing parameters, such as granular activated carbon packing density, outside diameter (OD) and the length of the thermal generator. This information is useful in choosing the correct typical standard tube size of the thermal generator with the granular activated carbon (208-C) / R723 pair for specific applications, based on optimum governing parameters, such as the range of heat source availability and the power requirement. The other key point which was examined was the effect of tubular generator body material on COP and SCP (SHP) for different applications. The model used stainless steel and Cu-Ni 90/10 with standard wall thickness.
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Raymond, Alexander William. "Investigation of microparticle to system level phenomena in thermally activated adsorption heat pumps." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34682.
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Heat actuated adsorption heat pumps offer the opportunity to improve overall energy efficiency in waste heat applications by eliminating shaft work requirements accompanying vapor compression cycles. The coefficient of performance (COP) in adsorption heat pumps is generally low. The objective of this thesis is to model the adsorption system to gain critical insight into how its performance can be improved. Because adsorption heat pumps are intermittent devices, which induce cooling by adsorbing refrigerant in a sorption bed heat/mass exchanger, transient models must be used to predict performance. In this thesis, such models are developed at the adsorbent particle level, heat/mass exchanger component level and system level.
Adsorption heat pump modeling is a coupled heat and mass transfer problem. Intra-particle mass transfer resistance and sorption bed heat transfer resistance are shown to be significant, but for very fine particle sizes, inter-particle resistance may also be important. The diameter of the adsorbent particle in a packed bed is optimized to balance inter- and intra-particle resistances and improve sorption rate. In the literature, the linear driving force (LDF) approximation for intra-particle mass transfer is commonly used in place of the Fickian diffusion equation to reduce computation time; however, it is shown that the error in uptake prediction associated with the LDF depends on the working pair, half-cycle time, adsorbent particle radius, and operating temperatures at hand.
Different methods for enhancing sorption bed heat/mass transfer have been proposed in the literature including the use of binders, adsorbent compacting, and complex extended surface geometries. To maintain high reliability, the simple, robust annular-finned-tube geometry with packed adsorbent is specified in this work. The effects of tube diameter, fin pitch and fin height on thermal conductance, metal/adsorbent mass ratio and COP are studied. As one might expect, many closely spaced fins, or high fin density, yields high thermal conductance; however, it is found that the increased inert metal mass associated with the high fin density diminishes COP. It is also found that thin adsorbent layers with low effective conduction resistance lead to high thermal conductance. As adsorbent layer thickness decreases, the relative importance of tube-side convective resistance rises, so mini-channel sized tubes are used. After selecting the proper tube geometry, an overall thermal conductance is calculated for use in a lumped-parameter sorption bed simulation. To evaluate the accuracy of the lumped-parameter approach, a distributed parameter sorption bed simulation is developed for comparison. Using the finite difference method, the distributed parameter model is used to track temperature and refrigerant distributions in the finned tube and adsorbent layer. The distributed-parameter tube model is shown to be in agreement with the lumped-parameter model, thus independently verifying the overall UA calculation and the lumped-parameter sorption bed model.
After evaluating the accuracy of the lumped-parameter model, it is used to develop a system-level heat pump simulation. This simulation is used to investigate a non-recuperative two-bed heat pump containing activated carbon fiber-ethanol and silica gel-water working pairs. The two-bed configuration is investigated because it yields a desirable compromise between the number of components (heat exchangers, pumps, valves, etc.) and steady cooling rate. For non-recuperative two-bed adsorption heat pumps, the average COP prediction in the literature is 0.39 for experiments and 0.44 for models. It is important to improve the COP in mobile waste heat applications because without high COP, the available waste heat during startup or idle may be insufficient to deliver the desired cooling duty. In this thesis, a COP of 0.53 is predicted for the non-recuperative, silica gel-water chiller. If thermal energy recovery is incorporated into the cycle, a COP as high as 0.64 is predicted for a 90, 35 and 7.0°C source, ambient and average evaporator temperature, respectively. The improvement in COP over heat pumps appearing in the literature is attributed to the adsorbent particle size optimization and careful selection of sorption bed heat exchanger geometry.
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Turner, Lynne Helen. "Improvement of activated charcoal-ammonia adsorption heat pumping/refrigeration cycles : investigation of porosity and heat/mass transfer chacteristics." Thesis, University of Warwick, 1992. http://wrap.warwick.ac.uk/35984/.
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Reported in this thesis are the results of a combined theoretical and experimental study into improvements to the solid adsorption refrigeration or heat pumping cycle using the ammonia-activated charcoal pair. The three areas which have been examined are the cycle thermodynamics, the porosity characteristics of ammonia-charcoal pairs and the heat transfer through an ammonia granular charcoal packed bed. It was found through the use of advanced thermodynamic cycles utilizing multiple beds that the coefficient of performance of a refrigerator could be increased by sv 250% and the coefficient of amplification of a heat pump could be increased by co 110%. The coefficients of performance and amplification may also be increased to a lesser degree by judicious choice of the charcoal porosity characteristics. A survey of charcoal porosity characteristics revealed that the useful energy per cycle could be doubled by the correct choice of charcoal. The thermal conductivity of an ammonia granular charcoal bed was measured using a novel piece of apparatus. From the results it was decided for all practical purposes that the bed conductivity may be considered constant and equal to 0.165 W/m K. The power output of the cycle was found from modelling the dynamic desorption of a reactor using a one-dimensional finite difference model set in radial coordinates. The cycle simulations revealed that ideally the reactor should be constructed from solid charcoal shapes manufactured in such a way as to incorporate paths of enhanced conductance and be integral with the containing vessel wall.
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Lefebvre, Dominique. "Thermal Energy Storage Using Adsorption Processes for Solar and Waste Heat Applications: Material Synthesis, Testing and Modeling." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34173.
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As the worldwide energy demand continues to increase, scientists and engineers are faced with the increasingly difficult task of meeting these needs. Currently, the major energy sources, consisting of oil, coal, and natural gas, are non-renewable, contribute to climate change, and are rapidly depleting. Renewable technology research has become a major focus to provide energy alternatives which are environmentally-friendly and economically competitive to sustain the future worldwide needs. Thermal energy storage using adsorption is a promising technology which can provide energy for heating and cooling applications using solar and waste heat sources. The current work aims to improve adsorption systems to provide higher energy outputs and therefore, more economical systems. New adsorbents and operating conditions were tested with the goal of storing the available energy more efficiently. A model was also developed to gain a better understanding of the adsorption system to improve this developing technology.
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Liao, Meng. "Modeling of fluid flows and heat transfer with interface effects, from molecular interaction to porous media." Thesis, Paris Est, 2018. http://www.theses.fr/2018PESC1054/document.
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Les objectifs de la thèse sont d'étudier le transport de fluide et le transfert de chaleur dans les pores micro et nanométriques. Les expériences et les simulations ont révélé des preuves de l'augmentation du flux provoquée par la vitesse de glissement à la paroi solide. D'autre part, la résistance thermique finie à l'interface fluide-solide est responsable de la différence de température des deux phases. Ces deux phénomènes d'interface peuvent avoir un impact considérable sur la perméabilité et la diffusivité thermique des milieux poreux constitués de micro et nanopores. La contribution se concentre sur l'étude des trois problèmes suivants. Premièrement, nous examinons les effets de glissement des liquides confinés dans un canal de graphème en utilisant le formalisme de Green Kubo et la méthode de la dynamique moléculaire. On montre que lorsque la surface solide est soumise à une contrainte mécanique uniaxiale, la friction présente une anisotropie due à la modification de l'énergie potentielle et de la dynamique des molécules composant le fluide. Les formes moléculaires jouent également un rôle important sur les écarts de frottement entre les deux directions principales. Deuxièmement, nous étudions le régime des gaz raréfiés. Dans ce cas, la vitesse de glissement et le saut de température sont régis par les collisions entre les atomes de gaz et la paroi solide. Ces effets peuvent être déterminés à l’aide d’un modèle statistique qui peut être construit à partir des vitesses incidente et réfléchie des molécules de gaz. A cette fin, différentes méthodes basées sur des techniques d'apprentissage statistique ont été proposées. Enfin, la méthode des éléments finis est utilisée pour calculer la perméabilité et la diffusivité thermique des milieux poreux sous l'influence des effets d'interface<br>The objectives of the thesis are to study the fluid transport and heat transfer in micro and nano-scale pores. Both experiments and simulations revealed evidence of an enhancement of flow-rate, originated from slip velocity at the solid boundary. On the other hand, the finite thermal resistance at the fluid-solid interface is responsible for the temperature difference between the two phases. These two interface phenomena can have a considerable impact on the permeability and thermal diffusivity of porous media constituted of micro and nano-pores. This contribution focuses on studying the following three issues. First, we examine the slip effects of liquids confined in graphene channel using Green Kubo formalism and Molecular Dynamics method. It is shown that when the solid surface is subject to mechanical uniaxial strain, the friction exhibits anisotropy due to the modification of the potential energy and the dynamics of the fluid molecules. The molecular shapes also play an important factor on the friction discrepancies between two principal directions. The quantification of both effects is addressed. Second, we investigate the rarefied gas regime. In this case, the velocity slip and temperature jump are governed by the collisions between the gas and the solid boundary. Those effects can be determined via the study of scattering kernel and its construction from MD simulation data. To this end, different methods based on statistical learning techniques have been proposed including the nonparametric (NP) kernel and Gaussian mixture (GM) kernel. Finally, the finite element method is used to compute the permeability and the thermal diffusivity of porous media under the influence of the interface effects
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Hussein, Eman. "Numerical and experimental evaluation of advanced metal-organic framework materials for adsorption heat pumps." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8626/.
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In this study the potential of a number of metal-organic framework materials namely; MIL-101(Cr), MIL-100(Fe), CP0-27(Ni) and aluminium fumarate was investigated in various adsorption applications such as heat pump, water desalination and heat storage. The properties of MIL-101(Cr) in terms of thermal conductivity and water vapour capacity were further improved through synthesizing novel composites with graphene oxide (GrO) and calcium chloride (CaCl\(_2\)). Also, the adsorption isotherm shape and capacity of MIL-100(Fe) were tuned through synthesizing two core-shell mechanism composites. The core-shell composites of MIL-101(Cr)/MIL-101(Fe) and CP0-27(Ni)/MIL 100(Fe) were synthesized to use the advantage of the high-water vapour uptake of MIL-101(Cr) in the high relative pressure and of CP0-27(Ni) in the low relative pressure range. Also, integrating the MOF material as a coated layer instead of the granular form was investigated as an alternative for conventional packed adsorption beds. MIL-100(Fe) and aluminium fumarate were chosen to be experimentally tested in a two-bed adsorption system. The effect of various operating conditions such as chilled water inlet temperature, cycle time, adsorption bed cooling water inlet temperature, desorption bed heating water inlet temperature and condenser cooling water inlet temperature was investigated.
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Füldner, Gerrit. "Measurement and modeling of mass transport in porous composite structures for adsorption heat pumps." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-191042.
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Füldner, Gerrit. "Measurement and modeling of mass transport in porous composite structures for adsorption heat pumps." Diffusion fundamentals 11 (2009) 82, S. 1-2, 2009. https://ul.qucosa.de/id/qucosa%3A14053.
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Yeboah, Siegfried Kwame. "An integrated packed bed-oscillating heat pipe system for energy efficient isothermal adsorption processes." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/48342/.
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Energy use in buildings accounts for a large portion of global and regional energy demand and energy-related CO2 emissions. To steer the world towards a low carbon future, the development of new and more efficient technologies is required. In hot and humid climates, the high latent heat loads results in uncomfortable and unhealthy indoor environments, accounting for 30% to 50% of standard air conditioning energy requirements. Physical adsorption of water vapour on solid desiccants is found to offer an energy efficient alternative to conventional dehumidification process using standard air conditioning systems. However, the isosteric heat of adsorption released increases the surface vapour pressure of the solid desiccants resulting in a decreased adsorption capacity. In packed beds of solid desiccants, this heat of adsorption increases the bed temperature, exit air temperature and exit air humidity ratio subsequently imposing an increased cooling load requirement and high energy requirement in the regeneration of the solid desiccants. In literature, several approaches used in removing in situ the heat of adsorption released in packed bed systems were fraught with several limitations. To this end, an integrated packed bed-oscillating heat pipe (OHP) system was proposed. The concept was for the evaporator of the OHP to remove the heat of adsorption generated by the packed bed and reject at its condenser towards an energy efficient isothermal adsorption process. To achieve this, theoretical investigations of the individual systems and the integrated systems preceded experimental testing of a rig set up in the laboratory. For the theoretical studies, the OHP was helically coiled at both ends, filled with ethanol, methanol and water working fluids respectively at 50% volume fraction and numerically investigated using the Eulerian Volume of Fluid (VOF) model in ANSYS Fluent R15.0. The packed bed on the other hand was configured as a Heggs et al (1994) Z-type flow arrangement for enhanced radial flow using the Porous Media model in ANSYS Fluent R15.0 set up with the properties of Silica Gel. ANSYS Fluent R15.0 System Coupling limitations led to the development of mathematical models for the prediction of the integrated system performance. The experimental investigations were in line with the theoretical only in this case the optimum working fluid, deionized water, was used as the main working fluid in the helically coiled OHP (HCOHP). The results showed reasonable agreement between the performance of the numerical model and experimental prototype. The HCOHPs were capable of passively removing heat from the packed bed systems. Mean bed temperature reduction between the integrated packed bed-HCOHP system and corresponding individual packed bed configurations were about 5.61°C, 9.48°C and 10.14°C respectively for the large annulus (LAPB), medium annulus (MAPB) and small annulus (SAPB) packed bed configurations. Average packed bed outlet temperature reductions of about 6.61°C, 9.19°C and 6.29°C were also achieved for the respective configurations. A validation of the theoretical model showed average temperature difference of about 5.60°C between the experimental prototype of the integrated system and results predicted using experimental packed bed temperature data and HCOHP thermal resistance. Compared to other similar systems in literature, the integrated packed bed-HCOHP system showed capacity to passively remove significant amounts of the heat of adsorption released in silica gel packed beds towards isothermal adsorption.
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Matemb, Ma Ntep Tobie [Verfasser]. "Modifications of Fumarate-Based Zirconium and Aluminum Metal-Organic Frameworks for Enhanced Gas Adsorption and Adsorption-driven Heat Transformation Applications / Tobie Matemb Ma Ntep." Düsseldorf : Universitäts- und Landesbibliothek der Heinrich-Heine-Universität Düsseldorf, 2020. http://d-nb.info/1202603726/34.
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Douss, Néjib. "Etude experimentale de cycles a cascades a adsorption solide." Paris 7, 1988. http://www.theses.fr/1988PA077052.
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Etude experimentale et simulation dynamique de systemes de pompe a chaleur a adsorption solide. Les systemes methanol-charbon actif et eau-zeolite sont etudies. Les conditions de temperature des composants (adsorbeur, condenseur et evaporateur) doivent etre homogenes pour la simulation. On considere les cycles intermittents (simple effet), a double effet et a triple effet (cycle a cascades). Determination d'un coefficient de performance pour la production du froid
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Fischer-Wolfarth, Jan-Henrik. "Adsorption energetics on Pd model catalysts by microcalorimetry." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2011. http://dx.doi.org/10.18452/16288.
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Die effiziente Nutzung der begrenzten Ressourcen auf der Erde ist ein entscheidender Faktor für ein nachhaltiges Leben. Die Entwicklung besserer Katalysatoren kann dabei einen wesentlichen Beitrag leisten. Ein umfassendes Verständnis der katalytischen Reaktivität würde es ermöglichen, spezifische katalytische Eigenschaften zu konzipieren und zu kontrollieren. In diese Arbeit wurde die Korrelation der Katalysatoroberfläche mit den Adsorptionswärmen von Molekülen aus der Gasphase untersucht. Insbesondere wurde die Adsorptionwärme von CO auf Pd-Partikeln als Funktion der Partikelgröße mittels gut charakterisierte Modelkatalysatorsysteme, eisenoxidgeträgerte Pd-Partikel, und UHV-Einkristalladsorptionskalorimetrie bestimmt. Es konnte die langjährige Kontroverse, wie sich die Adsorptionswärme von CO auf Pd mit der Partikelgröße ändert, aufgelöst werden. Die Adsorptionswärmen wurden für CO auf geträgerten Pd-Partikeln mit mittleren Größen zwischen 1.8 und 8 nm, sowie Pd(111) untersucht. Es zeigte sich dabei, dass die Anfangsadsorptionsenergie mit abnehmender Partikelgröße kleiner wird. Das Mikrokalorimeterexperiment besteht aus einer Präparationskammer und einer Kalorimetriekammer, die sowohl die Präparation und Charakterisierung von geträgerten metallischen Nanopartikeln, als auch Adsorptionsenergiemessungen ermöglichen. Das Kalorimeter basiert auf dem Design von Campbell et al. und nutzt eine pyroelektrische Folie als Detektor. Es wurden Verbesserungen in Bezug auf Ausrichtung, Temperaturstabilität und Vibrationsisolation implementiert. Ein gepulster Molekularstrahl wird eingesetzt, um die Oberfläche einem stabilen und homogenen Fluss von Gasphasenmolekülen auszusetzten. Desweiteren erlaubt ein In situ Reflektivitätsmessaufbau die Bestimmung der optischer Eigenschaften von Modelkatalysatoroberflächen, was entscheidend für eine akkurate Energiekalibration des Kalorimeters ist.<br>The efficient use of the limited resources on earth is a critical factor to sustainable life. The development of better catalysts can make a significant contribution. Complete understanding of the catalytic activity would facilitate the design and control of specific catalytic processes. In this work, the correlation of the catalyst structure and the heats of adsorption of gas-phase particles were investigated. In particular, the heat of adsorption for CO on Pd particles was determined as a function of particle size, using a well-characterized model catalyst system, Pd particles supported on an iron oxide film, and UHV single crystal adsorption microcalorimetry. It was possible to resolve the longstanding controversy, how the heat of adsorption of CO on Pd particles changes with particle size. The heat of adsorption for CO on Pd particles was studied on supported Pd particles with a mean diameter of 1.8 to 8 nm and Pd(111). The initial heat of adsorption was found to decrease with decreasing particle size. The completed microcalorimeter experiment comprises a preparation chamber and a calorimetry chamber, providing all means to prepare and characterize oxide supported metal nanoparticles and to perform adsorption energy measurements. The calorimeter is based on the design of Campbell et al., using a pyroelectric ribbon as a detector. Improvements with respect to alignment, temperature stability, and vibration isolation were implemented. A pulsed molecular beam is used to expose the surface to a stable and homogeneous flux of gas-phase molecules. Further, a dedicated in situ reflectivity measurement setup allows optical characterization of the model catalyst surfaces, which is crucial for an accurate energy calibration of the calorimeter.
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Flemming, Christine Juliette Jane. "Impact and nature of open metal sites: a water and carbon monoxide adsorption study on MOF-74 isostructural MOFs." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/48992.
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In this work the magnesium, zinc, nickel and cobalt MOFs of the MOF-74 isostructural family are used to probe metal-dependent adsorbate interactions with water and with carbon monoxide because of their ability to generate open metal sites upon activation. An isostructural family is used so that the only variable from one MOF to another is the metal incorporated into the framework. For water adsorption isotherms with humidities up to 90%, the observed trend at 298K and 1 bar is Mg-MOF-74 > Zn-MOF-74 > Co-MOF-74 > Ni-MOF-74. This observed trend is due to Lewis acid-base interactions. When the weight effect is removed, differences are still observed, especially below 40% relative humidity, thereby confirming that there is a metal effect. These studies revealed that PXRD alone cannot indicate the level of structural decomposition and that none of the four isostructures fully retain their structural integrity on exposure to humidified air because of microstrain and/or the presence of oxygen; more studies examining the extent of structural decomposition need to be undertaken. For carbon monoxide adsorption the general observed trend for P < 4 bar and temperatures of 298, 313 and 333K is Co-MOF-74 > Ni-MOF-74 > Zn-MOF-74 > Mg-MOF-74. This trend is based on π-backbonding interactions. Here again, differences remain after removal of the weight effect, confirming the metal dependence. Notably, Co-MOF-74 has the highest CO loading at 298K and 1 bar reported so far. Both the Toth and Virial Isotherms were used to fit the CO adsorption data followed by the use of the Clausius-Clapeyron equation to find the isosteric heats of adsorption, qst. The results from the Toth isotherm are more reliable and showed that qst remains constant as loading increases for Mg-MOF-74, decreases for Zn-MOF-74 and increases with loading for Co-MOF-74 and Ni-MOF-74; Ni-MOF-74 had the highest heat of adsorption at all loadings. It appears that using the Clausius-Clapeyron equation to calculate qst is an inappropriate method for Ni-MOF-74 so other methods such as calorimetry are recommended. It is also recommended to model the data of all the MOFs with other isotherm models such as Sips equation and to investigate the possibility of chemisorption for the cobalt and nickel isostructures. Finally, Henry’s constant results reveal that Ni-MOF-74 has the highest affinity for CO at low coverages.
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Charalambous, Constantinos. "An investigation of an adsorption cogeneration system for power and cooling using low grade heat." Thesis, University of Newcastle upon Tyne, 2015. http://hdl.handle.net/10443/2891.
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Cogeneration is a hot topic in the efforts to reduce dependence on fossil fuel usage and to reduce greenhouse gas emissions by replacing the primary energy source with a low-grade heat source. Cogeneration simultaneously produces power and cooling using a low-grade heat source (e.g. solar energy, geothermal energy or waste heat), which ideally provides a renewable carbon-free solution for implementation in domestic, industrial as well as isolated areas. This research thesis describes for the first time the development and construction of the Low Heat cogeneration chemisorption system, explores its potential and makes suggestions for its future development based on the experience gained during the experiments. The design uses two adsorption cycles operating out of phase and alternatively connected to a scroll expander in order to reach 3kW of cooling and 1kW of electricity. Each adsorption cycle consists of a reactor, a condenser and an evaporator. Each reactor contains a composite mixture of CaCl2 and activated carbon at a ratio of 4:1 by mass. The system was experimentally investigated for its cooling as well as for its cogeneration performance. Experimental investigations were performed for different heating and cooling temperatures, cycle times and the optimum overall ammonia for the system. The maximum refrigeration coefficient of the performance (COPref) of the machine was found to be 0.26 when the refrigeration power was 3.52kW. At the same time, the specific cooling power (SCP) per side was 201.14W/kg (402.28W/kg per cycle) and the cooling capacity 168.96kJ/kg (337.92kJ/kg per cycle). During the cogeneration experiments it was found that the expander affected the pressure and temperature; the refrigerant flow rate and the pressure across the expander were important for the system’s power production. The maximum power recorded was 486W which provides a power coefficient of performance (COPW) of 0.048. A model to describe the desorption power generation as well as the evaporation refrigeration process was developed using the ECLIPSE software. The cooling model was validated from the experimental results and later the power model was used for ii further investigation of the system power performance. The optimisation of the machine completes the study by using both experimental and simulation data.
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Vaidya, Prahar S. "PURE AND BINARY ADSORPTION OF METHANE AND NITROGEN ON SILICALITE." Cleveland State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=csu1463751121.
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Mostafavi, Mahmood. "Theoretical and experimental investigation of using power plants (diesel engines) waste heat for adsorption refrigeration applications." Thesis, University of Newcastle Upon Tyne, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307832.
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Sen, Ali Umut. "Caracterização e fraccionamento da casca de Quercus serris para separação da cortiça tendo em vista a sua utilização em aglomerados." Doctoral thesis, ISA/UTL, 2012. http://hdl.handle.net/10400.5/5206.
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Doutoramento em Engenharia Florestal e dos Recursos Naturais - Instituto Superior de Agronomia<br>Quercus cerris bark was studied with the following objectives: i) to study
bark anatomy, ii) to separate and determine chemical composition of cork,
iii) to analyze the thermal behavior of cork, iv) to investigate the use of
cork as adsorbent of pollutants in aqueous environments and v) to compare
the results obtained with those from Quercus suber.
The bark of Q. cerris is composed of phloem, periderm and rhytidome. The
rhytidome contains various sequential periderms with large portions of cork
and many sclerified tissues. The cork structure is similar to that of Q. suber,
but the cells are smaller and have higher solid fraction.
The chemical composition of cork of Q. cerris is similar to that of Q. suber
but suberin content is less and it is formed largely by ω-hidroxyacids. The
thermal degradation starts at 200°C and increases with temperature and
treatment time. Suberin was thermically more resistant. The colour was
altered until 40% of mass loss. A mass loss model was developed with
colour change values.
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Moore, Bryce Kirk. "Gas-liquid flows in adsorbent microchannels." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47519.
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A study of two the sequential displacement of gas and liquid phases in microchannels for eventual application in temperature swing adsorption (TSA) methane purification systems was performed. A model for bulk fluid displacement in 200 m channels was developed and validated using data from an air-water flow visualization study performed on glass microchannel test sections with a hydraulic diameter of 203 m. High-speed video recording was used to observe displacement samples at two separate channel locations for both the displacement of gas by liquid and liquid by gas, and for driving pressure gradients ranging from 19 to 450 kPa m-1. Interface velocities, void fractions, and film thicknesses were determined using image analysis software for each of the 63 sample videos obtained.
Coupled 2-D heat and mass transfer models were developed to simulate a TSA gas separation process in which impurities in the gas supply were removed through adsorption into adsorbent coated microchannel walls. These models were used to evaluate the impact of residual liquid films on system mass transfer during the adsorption process. It was determined that for a TSA methane purification system to be effective, it is necessary to purge liquid from the adsorbent channel. This intermediate purge phase will benefit the mass transfer performance of the adsorption system by removing significant amounts of residual liquid from the channel and by causing the onset of rivulet flow in the channel. The existence of the remaining dry wall area, which is characteristic of the rivulet flow regime, improves system mass transfer performance in the presence of residual liquid.
The commercial viability of microchannel TSA gas separation systems depends strongly on the ability to mitigate the presence and effects of residual liquid in the adsorbent channels. While the use of liquid heat transfer fluids in the microchannel structure provides rapid heating and cooling of the adsorbent mass, the management of residual liquid remains a significant hurdle. In addition, such systems will require reliable prevention of interaction between the adsorbent and the liquid heat transfer fluid, whether through the development and fabrication of highly selective polymer matrix materials or the use of non-interacting large-molecule liquid heat transfer fluids. If these hurdles can be successfully addressed, microchannel TSA systems may have the potential to become a competitive technology in large-scale gas separation.
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Yeung, King-ho, and 楊景豪. "An optimization model for a solar hybrid water heating and adsorption ice-making system." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B29632432.
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Das, Anita. "Metal- Organic Frameworks as a Platform for Elucidating the Effects of Functional Sites on CO2 Interaction." Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/13813.
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This thesis reports an investigation into metal-organic frameworks (MOFs) as candidate solid-state carbon dioxide capture materials. The modulation of CO2 uptake and heat of adsorption (|Qst|) were explored in response to the systematic variation of pore size, surface area and/or functionalisation in a range of targeted MOFs. Chapter 3 exploits ligand design and targeted MOF synthesis. Functionalised ligands based on the 4,4′-biphenyldicarboxylate core were generated through facile synthetic routes and incorporated into known MOF topologies, including the cubic UiO topology, the pillared paddlewheel topology and IRMOF-9 topology. Through the variation of metal, pore size and/or functionality in each of these series, general correlations between structure and degree of CO2 interaction with the adsorbate were elucidated. The problematic nature of unpredictable MOF self-assembly are also discussed Chapter 3, in which the synthesis, characterisation, and properties of four novel MOFs have been examined. Chapter 4 investigates post-synthetic modification (PSM) as an approach to generate more polar functional sites. PSM was undertaken in two framework types, microporous UiO-66 and mesoporous MIL-101, to investigate the effect of pore size on both the extent of PSM and its influence on CO2 uptake. In the mesoporous case, the polar functional sites increased CO2 uptake in all cases despite lower surface areas, suggesting that for larger pore frameworks, this is an effective strategy for enhancing CO2 uptake. Chapter 5 explores the potential for interplay between CO2 uptake and optical properties in MOFs through the use of CO2-reactive sites tethered to fluorophores in the porous structures. The results suggest that MOFs containing the arginine moiety are promising candidate CO2 chemosensors, as they exhibited strong linear fluorescence responses with increased CO2 dosing. This chapter presents a promising approach to the design of novel chemosensors.
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Taheri, Hadi [Verfasser], and M. [Akademischer Betreuer] Gabi. "Numerical Investigation of Stratified Thermal Storage Tank Applied in Adsorption Heat Pump Cycle / Hadi Taheri. Betreuer: M. Gabi." Karlsruhe : KIT-Bibliothek, 2014. http://d-nb.info/1051848180/34.
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Joshi, Chirag [Verfasser], and M. [Akademischer Betreuer] Gabi. "Experimental Investigations of Adsorption Chiller Cycle Using Stratified Thermal Storage for Heat Recovery / Chirag Joshi. Betreuer: M. Gabi." Karlsruhe : KIT-Bibliothek, 2016. http://d-nb.info/1103574078/34.
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Charalambous, Charithea. "Temperature swing adsorption process for carbon dioxide capture, purification and compression directly from atmospheric air." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/33311.
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Many reports, scientific papers, patents, and scientific news investigate the feasibility and affordability of direct carbon dioxide capture from the atmospheric air (DAC). Since carbon dioxide (CO2) is extremely diluted in the atmosphere, large volumes of air have to be handled to capture comparable amounts of CO2. Therefore, both the energy consumption and the plant size are expected to be 'prohibitive'. On the other hand, some analyses have shown that DAC is feasible and can become affordable with essential research and development. DAC has been regarded as an optional bridging or a transitional technology for mitigating CO2 emissions in the medium-term. Priorities include investing in renewable and low-carbon technologies, efficiency and integration of energy systems, and realisation of additional environmental benefits. A heavy reliance on negative emission technologies (NETs), and consequently DAC, may be extremely risky as NETs interact with a number of societal challenges, i.e. food, land, water and energy security. Although, "... capturing carbon from thin air may turn out to be our last line of defence, if climate change is as bad as the climate scientists say, and if humanity fails to take the cheaper and more sensible option that may still be available today" MacKay (2009). Certainly, more research is necessary to bring down both cost and energy requirements for DAC. This work firstly predicts the adsorption equilibrium behaviour of a novel temperature swing adsorption process, which captures carbon dioxide directly from the air, concentrates, and purifies it at levels compatible to geological storage. The process consists of an adsorption air contactor, a compression and purification train, which is a series of packed beds reduced in size and connected in-line for the compression and purification purposes, and a final storage bed. The in-line beds undergo subsequent adsorption and desorption states. The final desorbed stream is stored in a storage bed. This cyclic process is repeated for a number of times imposed by the required purity and pressure in the final bed. The process is been thermodynamically verified and optimised. Since, the overall performance of this process does not only depend on the design of the process cycle and operating conditions but also on the chosen adsorbent material, further optimisation of the adsorptive and physical properties of the solid adsorbent is investigated. Thus, the optimal parameters of the potentially used porous materials is identified. Continuing the research on different adsorbent materials, an experimental investigation on the equilibrium properties of two competitive adsorbents is also performed. Besides the thermodynamic analysis, a dynamic model is presented for the investigation of the mass and heat transfer and its influence on the adsorption rate and consequently on the overall process performance. Since the initial stream is very dilute, it is expected that the adsorption rate will be low compared to other temperature swing processes and the capture rate will be affected by the heat transfer. Finally, the design and development of an experimental laboratory-scale apparatus is presented and analysed. Future design improvements are also discussed.
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Splith, Tobias, Christian Chmelik, Frank Stallmach, et al. "Adsorptive heat transformation with SAPO-34: diffusion of working fluids water, methanol and ethanol." Diffusion fundamentals 24 (2015) 51, S. 1, 2015. https://ul.qucosa.de/id/qucosa%3A14570.
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Mendonça, Mileo Paulo Graziane. "Computational exploration of water adsorption and proton conduction in porous materials." Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTS142/document.
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L’objectif de la thèse a été de comprendre la dynamique protonique et l'adsorption d'eau dans de nouveaux matériaux poreux identifiés expérimentalement comme des candidats prometteurs pour des applications dans le domaine de la conduction protonique et du transfert de chaleur par adsorption. Dans ce contexte, des simulations à l’échelle électronique (Théorie de la fonctionnelle de la Densité) et atomique (Monte Carlo et Dynamique Moléculaire classique) ont permis (i) d’élucider les mécanismes de conduction protonique assistées par l’eau de deux matériaux hybrides de type MOFs, MIL-163(Zr) et KAUST-7', et d'un phosphate de titane, TiIVTiIV(HPO4)4 à l’origine de leurs performances exceptionnelles et (ii) d’interpréter les comportements d’adsorption de l’eau d’une série de matériaux hybrides CUK-1(Me), MOF-801(Zr) and MIL-100(Fe) qui peuvent être modulées par la nature de leur centre métallique, la création de défauts et l’incorporation de sites de coordination insaturés. Cette connaissance fondamentale devrait permettre de voir émerger de façon plus efficace des matériaux pour les deux applications visées<br>The objective of this PhD thesis was to gain insight into the proton dynamics and water adsorption mechanisms in novel porous materials that have been identified experimentally as promising candidates for low temperature proton conduction and adsorption-based heat reallocation-related applications. This was achieved by combining advanced computational tools at the electronic (Density Functional Theory) and atomic (force field_based Monte Carlo and Molecular Dynamics) levels to (i) reveal the water-assisted proton migration pathway through the pores of the hybrid metal organic frameworks MIL-163(Zr) and KAUST-7’and the inorganic phosphonate TiIVTiIV(HPO4)4 materials at the origin of their outstanding proton conduction performances and (ii) explain the water adsorption behaviors of a series of metal organic frameworks CUK-1(Me), MOF-801(Zr) and MIL-100(Fe) that can be tuned by changing the nature of the metal center, creating defects and incorporating coordinatively unsaturated sites. Such a fundamental understanding is expected to pave the way towards a more efficient development of materials for the two explored applications
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Ahamat, Mohamad Asmidzam. "Development of a novel adsorption calorimeter : applications to silica gels bonded to flat and finned metal heat exchange surfaces." Thesis, University of Bristol, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.556717.
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The primary objective of this thesis was to develop a novel adsorption calorimeter to assess the equilibrium and dynamic behaviour of adsorbent-bond- metal sub-system, a constituent of an adsorption chiller. In this research, a novel calorimeter consisting of an adsorber and an evaporator section has been built. Thermoelectric modules were used to control the temperature and measure the instantaneous heat flow at the adsorber and evaporator sections. This thermoelectric module system was tested against an inert aluminium sample. The aluminium sample temperatures were controlled to constant, sinusoidal and triangular set point to within 0.1 K (1 standard deviation). The effective Seebeck coefficient and thermal conductance of the module were extracted from the calibration experiment. The inferred heat flow had a typical accuracy of 10 %. Further tests with a sinusoidal temperature variation yielded the root mean square error of cumulative heat flow as - 8 %. Three and one mm nominal diameter Type A silica gel beads were chosen as the adsorbent, and water as the refrigerant. In the adsorption-evaporation experiment, the plot of heat of adsorption versus time was well fitted to exponential recovery (r2 > 99%). Cumulative net heat flow at the adsorber at time equal to infinity gave the adsorptive capacity, while the time to reach 63.2 % of this value gave the apparent Linear Driving Force constant (Kldf). Adsorptive capacities of the silica gels were fitted to Henry's law and were within 20 % of previously published data. Specific heats of adsorption (obtained by Arrhenius plots of the Henry's law constants) were 2495 kJ/kg and 2634 kJ/kg for 3 and 1 mm diameter gel beads respectively, which were within 9 % of the published data (2710 kJ/kg). Specific heat of adsorption for both samples, calculated from energy balance, were within 8.4 % of values inferred from Arrhenius plot of the Henry Law coefficient. The apparent Kldf for 1 mm diameter gel-beads was 3 times higher compared to the one for 3 mm diameter beads. Activation energy (1261 kJ/kg for 3 mm diameter beads and 1537 kJ/kg for 1 mm diameter beads) was obtained from a further Arrhenius plot, and was between 50 and 58% of the specific heat of adsorption. This suggests the surface diffusion is the governing mechanism for the water adsorption onto silica gel. Tests with de sorption- condensation and temperature varied sinusoidally versus time revealed the ineffectiveness of the water-containing section when acting as a condenser. The adsorption behaviour of coated fins was studied experimentally. The apparent K1df for silica gel coated to a stainless steel fin bonded to an isothermal aluminium plate was ~ 50 % less than that of silica gel bonded directly to flat plate. For an aluminium fin that was cut from a single piece of metal, the apparent Kldf was reduced by 10 %. A numerical model predicted the apparent K1df of the coated fin with an accuracy better than 22 %. The model was developed using the rate constant for silica gel bonded onto a flat plate, the thermal contact resistance at the. root of the fin (if applicable) and the temperature gradient along the fin. Other fin configurations that were not tested experimentally were simulated in the model. In an adsorption chiller, it is estimated that a specific cooling power as high as 275 W/kg and 750 W/kg could be obtained for the 3 and 1 mm diameter gel beads bonded to the flat plate heat exchange surface. For the silica gels coated onto 20 mm high aluminium fins (1 mm thickness), the specific cooling power could be reduced by 30 and 33 % for 3 and 1 mm diameter gel beads respectively. The specific cooling power is sensitive to the adsorber configuration and cycle time.
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Gondre, Damien. "Numerical modeling and analysis of heat and mass transfers in an adsorption heat storage tank : Influences of material properties, operating conditions and system design on storage performances." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI022/document.
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Le développement de solutions de stockage de l'énergie est un défi majeur pour permettre la transition énergétique d'un mix énergétique fortement carboné vers une part plus importante des énergies renouvelables. La nécessité de stocker de l'énergie vient de la dissociation, spatiale et temporelle, entre la source et la demande d'énergie. Stocker de l'énergie répond à deux besoins principaux : disposer d'énergie à l'endroit et au moment où on en a besoin. La consommation de chaleur à basse température (pour le chauffage des logements et des bureaux) représente une part importante de la consommation totale d'énergie (environ 35 % en France en 2010). Le développement de solutions de stockage de chaleur est donc d'une grande importance, d'autant plus avec la montée en puissance des énergies renouvelables. Parmi les technologies de stockage envisageables, le stockage par adsorption semble être le meilleur compromis en termes de densité de stockage et de maintient des performances sur plusieurs cycles de charge-décharge. Cette thèse se focalise donc sur le stockage de chaleur par adsorption, et traite de l'amélioration des performances du stockage et de l'intégration du système au bâtiment. L'approche développée pour répondre à ces questions est numérique. L'influence des propriétés thermophysiques de l'adsorbant et du fluide sur la densité de puissance d'une part, mais aussi sur la densité de stockage et l'autonomie du système, est étudiée. L'analyse des résultats permet de sélectionner les propriétés des matériaux les plus influentes et de mieux comprendre les transferts de chaleur et de masse au sein du réacteur. L'influence des conditions opératoires est aussi mise en avant. Enfin, il est montré que la capacité de stockage est linéairement dépendante du volume de matériau, tandis que la puissance dépend de la surface de section et que l'autonomie dépend de la longueur du lit d'adsorbant. Par ailleurs, le rapport entre l'énergie absorbée (charge) et relâchée (décharge) est d'environ 70 %. Mais pendant la phase de charge, environ 60 % de la chaleur entrant dans le réacteur n'est pas absorbée et est directement relâchée à la sortie. La conversion globale entre l'énergie récupérable et l'énergie fournie n'est donc que de 25 %. Cela montre qu'un système de stockage de chaleur par adsorption ne peut pas être pensé comme un système autonome mais doit être intégré aux autres systèmes de chauffage du bâtiment et aux lois de commande qui les régissent. Utiliser la ressource solaire pour le préchauffage du réacteur est une idée intéressante car elle améliore l’efficacité de la charge et permet une réutilisation de la part récupérée en sortie pour le chauffage direct du bâtiment. La part stockée sous forme sensible peut être récupérée plusieurs heures plus tard. Le système est ainsi transformé en un stockage combiné sensible/adsorption, avec une solution pour du stockage à long terme et pour du stockage à court terme<br>The development of energy storage solutions is a key challenge to enable the energy transition from fossil resources to renewable energies. The need to store energy actually comes from a dissociation between energy sources and energy demand. Storing energy meets two principal expectations: have energy available where and when it is required. Low temperature heat, for dwellings and offices heating, represents a high share of overall energy consumption (i.e. about 35 %). The development of heat storage solutions is then of great importance for energy management, especially in the context of the growing part of renewable energies. Adsorption heat storage appears to be the best trade off among available storage technologies in terms of heat storage density and performances over several cycles. Then, this PhD thesis focuses on adsorption heat storage and addresses the enhancement of storage performances and system integration. The approach developed to address these issues is numerical. Then, a model of an adsorption heat storage tank is developed, and validated using experimental data. The influence of material thermophysical properties on output power but also on storage density and system autonomy is investigated. This analysis enables a selection of particularly influencing material properties and a better understanding of heat and mass transfers. The influence of operating conditions is also underlined. It shows the importance of inlet humidity on both storage capacity and outlet power and the great influence of discharge flowrate on outlet power. Finally, it is shown heat storage capacity depends on the storage tank volume, while outlet power depends on cross section area and system autonomy on bed length. Besides, the conversion efficiency from absorbed energy (charge) to released energy (discharge) is 70 %. But during the charging process, about 60 % of incoming heat is not absorbed by the material and directly released. The overall conversion efficiency from energy provided to energy released is as low as 25 %. This demonstrates that an adsorption heat storage system cannot be thought of as a self-standing component but must be integrated into the building systems and control strategy. A clever use of heat losses for heating applications (in winter) or inlet fluid preheating (in summer) enhances global performances. Using available solar heat for system preheating is an interesting option since a part is instantly retrieved at the outlet of the storage tank and can be used for direct heating. Another part is stored as sensible heat and can be retrieved a few hours later. At least, it has the advantage of turning the adsorption storage tank into a combined sensible-adsorption storage tank that offers short-term and long-term storage solutions. Then, it may differ avoidable discharges of the sorption potential and increase the overall autonomy (or coverage fraction), in addition to optimizing chances of partial system recharge
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Yongsunthon, Isarez. "Design of periodic adsorptive reactors for the optimal integration of reaction, separation and heat-exchange." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314148.
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Caglar, Ahmet. "Design And Experimental Testing Of An Adsorbent Bed For A Thermal Wave Adsorption Cooling Cycle." Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614754/index.pdf.
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Poor heat and mass transfer inside the adsorbent bed of thermal wave adsorption cooling cycles cause low system performance and is an important problem in the adsorbent bed design. In this thesis, a new adsorbent bed is designed, constructed and tested to increase the heat and mass transfer in the adsorbent bed. The adsorbent bed is constructed from a finned tube in order to enhance the heat transfer. Additionally, the finned bed geometry is theoretically modeled and the model is solved time dependently by using Comsol Multiphysics software program. The distributions of dependent variables, i.e. temperature, pressure and amount adsorbed, are simulated and plotted in Comsol Multiphysics. In the model, the dependent variables are computed by solving the energy, mass and momentum transfer equations in a coupled way and their variations are investigated two-dimensionally. The results are presented with multicolored plots in a 2-D domain. Furthermore, a parametric study is carried out for determining factors that enhance the heat and mass transfer inside the adsorbent bed. In this parametric study, the effects of several design and operational parameters on the dependent variables are investigated. In the experimental study, the finned tube is tested using natural zeolite-water and silica gel-water working pairs. Temperature, pressure and amount adsorbed variations inside the adsorbent bed at various operating conditions are investigated. After that, a second adsorbent bed with a larger size is constructed and tested. The effect of the particle diameter of the adsorbent is also investigated. The experimental and theoretical results are compared.
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Davies, Gareth N. L. "Heat driven adsorption cooling utilising enhanced effective thermal conductivity monolithic adsorbent generators for refrigeration and ice production in developing countries." Thesis, University of Warwick, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364596.
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Krishnamurthy, Nagendra. "A Study of Heat and Mass Transfer in Porous Sorbent Particles." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/64412.
Full textAbstract:
This dissertation presents a detailed account of the study undertaken on the subject of heat and mass transfer phenomena in porous media. The current work specifically targets the general reaction-diffusion systems arising in separation processes using porous sorbent particles. These particles are comprised of pore channels spanning length scales over almost three orders of magnitude while involving a variety of physical processes such as mass diffusion, heat transfer and surface adsorption-desorption. A novel methodology is proposed in this work that combines models that account for the multi-scale and multi-physics phenomena involved. Pore-resolving DNS calculations using an immersed boundary method (IBM) framework are used to simulate the macro-scale physics while the phenomena at smaller scales are modeled using a sub-pore modeling technique.
The IBM scheme developed as part of this work is applicable to complex geometries on curvilinear grids, while also being very efficient, consuming less than 1% of the total simulation time per time-step. A new method of implementing the conjugate heat transfer (CHT) boundary condition is proposed which is a direct extension of the method used for other boundary conditions and does not involve any complex interpolations like previous CHT implementations using IBM. Detailed code verification and validation studies are carried out to demonstrate the accuracy of the developed method.
The developed IBM scheme is used in conjunction with a stochastic reconstruction procedure based on simulated annealing. The developed framework is tested in a two-dimensional channel with two types of porous sections - one created using a random assembly of square blocks and another using the stochastic reconstruction procedure. Numerous simulations are performed to demonstrate the capability of the developed framework. The computed pressure drops across the porous section are compared with predictions from the Darcy-Forchheimer equation for media composed of different structure sizes. The developed methodology is also applied to CO2 diffusion studies in porous spherical particles of varying porosities.
For the pore channels that are unresolved by the IBM framework, a sub-pore modeling methodology developed as part of this work which solves a one-dimensional unsteady diffusion equation in a hierarchy of scales represented by a fractal-type geometry. The model includes surface adsorption-desorption, and heat generation and absorption. It is established that the current framework is useful and necessary for reaction-diffusion problems in which the adsorption time scales are very small (diffusion-limited) or comparable to the diffusion time scales. Lastly, parametric studies are conducted for a set of diffusion-limited problems to showcase the powerful capability of the developed methodology.<br>Ph. D.
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Füldner, Gerrit [Verfasser], and Joachim [Akademischer Betreuer] Luther. "Stofftransport und Adsorptionskinetik in porösen Adsorbenskompositen für Wärmetransformationsanwendungen = Mass transfer and adsorption kinetics in porous adsorbent composites for heat transformation applications." Freiburg : Universität, 2015. http://d-nb.info/1115253514/34.
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Yun, Ji Sub. "Purification of Indoor Air Pollutants Utilizing Hydrophobic Adsorbents." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/41613.
Full textAbstract:
Sick building syndrome (SBS) is a particular concern in places with inadequate ventilation
and frequently attributed to chemical contaminants such as volatile organic compounds (VOCs)released from indoor sources that are frequently encountered in everyday life such as adhesives, carpeting, upholstery, manufactured wood products, copy machines, pesticides, cleaning agents inside buildings, plumbing vents, and painting. Furthermore, it is a major issue for modern human beings who spend most of their time indoors or must stay indoors for self-isolation due to special circumstances such as the coronavirus disease-19 (COVID-19) pandemic that occurred in 2019 and 2020. Main indoor VOCs are trichloroethylene (TCE), benzene, toluene, and para-xylene (p-xylene). In general, these compounds are not present in indoor spaces at acute concentrations, but prolonged exposure to these compounds can have chronic health effects such as allergic sensitization, increased cancer risks, and respiratory diseases.
In this study, the adsorption process with various advantages has been applied to remove
VOC’s using commercially available hydrophobic adsorbents. The hydrophobic adsorbents can contribute to reducing the possibility of chemical adsorption (chemisorption) of moisture from the air, which can decrease the capacity of adsorbent by clogging the pores. The adsorption of these major VOCs was investigated in this work for three major types of industrial hydrophobic adsorbents: activated carbons, zeolites, and polymer.
This study will show the investigation into finding the most promising hydrophobic
adsorbent for removal of TCE, benzene, toluene, and p-xylene, which are the main VOCs found indoors. The promising hydrophobic adsorbent has been determined by comparing Henry’s law constants and heat of adsorption values for the different adsorbents, which were estimated by using a concentration pulse chromatographic technique by utilizing a gas chromatograph equipped with a flame ionization detector.
For all adsorbents, Henry’s law constants at room temperature of p-xylene were always
the highest followed by toluene, benzene, and TCE. For all adsorbates, Henry’s law constants at room temperature of AC BPL and HiSiv 3000 were higher than the other hydrophobic adsorbents.
For a developing modern society dealing with a pandemic, this study can contribute to
producing the optimized gas masks and indoor filters for the removal of indoor air pollutants,
which can help people who suffer from SBS. It can also help society for taking preventative actions towards dealing with SBS.