京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第22486号 / 農博第2390号 / 新制||農||1075(附属図書館) / 学位論文||R2||N5266(農学部図書室) / 京都大学大学院農学研究科森林科学専攻 / (主査)教授 髙野 俊幸, 教授 和田 昌久, 教授 河本 晴雄 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

Master´s thesis deals with desing of a heated bed for FDM 3D printer using the finite element method. It is briefly described the history of RepRap printers, construction and mechanical parts. Are discussed two methods of heating, heated by PCB boards and using power resistors. Furthermore is work closely focused on power resistors. There are presented methods and procedures which leads to an optimal distribution of heated components on the board of heated bed. In conclusion are presented results of testing which are compared with the simulations in ANSYS.

The implementation of an energy recovery system for retreiving otherways wasted energy is an effective method for reducing the overall energy consumption of a mobile machine. In a fork lift, there are two subsystems that can be effectively modified for recovering energy. These are the driveline and the lift/lower function of the mast. This study focuses on the latter by studying a recovery system whose main component is a hydraulic transformer consisting of a hydraulic motor, a variable displacement pump and an induction motor. Since the flow rate/pressure - ratio can be modified, the utilization of the hydraulic transformer enables downsizing of the accumulator volume. However, the decrease of the gas volume leads to an increase in the compression ratio of the accumulator, which in terms leads to higher gas temperatures after charging and consequently to higher thermal losses during holding phase. In order to reduce these losses, a thermally regenerative unit was implemented to the gas volume of an accumulator to reduce the temperature build up during charging. In this study, the effect of improving the thermal characteristics of the accumulator to the efficiency of the whole energy recovery system is investigated by means of measurements.

The emergence of Thermally Driven Cooling system has received more attention recently due to its ability to utilize low grade heat from engine, incinerator or simple flat plate solar collector which are considered as renewable energy sources. ClimateWell AB located in Stockholm has been developing this cooling system based on its patented chemical heat pump technology. The heat pump with its tube shape is put under the absorber as in simple flat plate solar collector making it possible be directly attached on the roof without any additional solar collector. A high performance heat exchanger is needed by its reactor to absorb the energy efficiently during the desorption process as well as to recover heat during the absorption process. Current heat exchanger design has direct contact with the tube’s surface, yet air gaps between the tube and heat exchanger result in alower amount of heat transferred and non-uniform heat distribution across this surface. Moreover, a special treatment which cannot be done by machinery has to be performed in attaching the tube with this heat exchanger. It becomes a problem during mass production since a lot of man power is needed. A new heat exchanger design was proposed to overcome those limitations. This design has annulus which is filled with thermal fluid inside. This fluid will make perfect contact to the heat pump tube’s surface and eliminate the air gap. Furthermore, the need of man power in its production can be minimized. Even though perfect contact can be achieved, the fluid in this new design will increase thermal resistance in the radial direction. Therefore, an investigation has to be conducted to evaluate the performance of this new heat exchanger design based on heat transfer coefficient under steady state condition. The performance investigation also included the influence of various thermal fluids which will be used for this new heat exchanger. The work performed by doing simulation in COMSOL continued with validation of the result with experiment in laboratory. New heat exchanger design efficiency was only 50% while the current one was 82% during the desorption process. In this process, the fluid’s thermal conductivity was the most influencing fluid property. During absorption process, two heat recovery methods are used. First is by flowing the fluid inside the annulus and second is by using additional heat recovery pipe that is attached outside the heat exchanger surface. The first method gave the highest UA value around 34 W/K while the second one gave almost the same value as the current design which is around 11 W/K. In the first method, the thermal fluid’s viscosity strongly influenced its UA value while the second method is greatly influenced by fluid’s heat conductivity.

An enhanced-modularity thermally driven chemical heat pump was conceptualised as a second generation product for various heating and cooling applications with special emphasis on solar applications. The typical characteristics of the absorption heat pump were studied and the key performance parameters were selected for further investigation. An experimental test rig was constructed to allow for the testing of each component’s performance characteristics with special attention being paid to the ability to interchange components to test various configurations as well as to the facilitation of standardised relatively rapid testing. The heat transfer coefficient of the condenser/evaporator was found to be between 260 and 300 W/m2-°C during evaporation and between 130 and 170 W/m2-°C during condensation. Salt type has major impact on the system’s cooling power and cooling energy with the LiBr and water sorption pair having a 62% higher cooling/heating power than LiCl with the same matrix type and thickness. Matrix types and sorption pairs were compared with regards to the principal parameters of power and energy density with results ranging from 60 to 163 Wh/litre. The final section of the study tackled the theoretical foundation behind the system processes with modelling and simulation of the processes and comparison with the experimental data. The model makes the foundation of the continuous development of a more detailed and accurate physical model to enhance the design and optimisation process of the system.

L’objectif de cette thèse était de concevoir denouveaux matériaux polymères hydrophobes pour la protectionde composants semi-conducteurs, résistants à hautetempérature, aux forts champs électriques et aux atmosphèresagressives. Dans ce contexte, les polyimides d’addition sontapparus comme la famille de polymères la mieux adaptée pourl’application envisagée. La synthèse de l’encapsulant étantréalisée directement dans les boîtiers des modules, elle ne peutdonc pas contenir de solvant organique exogène. Ainsi, nousavons développé de nouvelles voies de synthèse sans solvantde poly(aminobismaléimide)s et de poly(bismaléimide)s.Dans un premier temps, différentes diamines aliphatiques ontété utilisées comme solvant réactif lors de la synthèse depoly(aminobismaléimide)s à une température bien inférieure à latempérature de fusion du bismaléimide utilisé (Tf > 300 °C). Unepremière série de 3 nouveaux poly(aminobismaléimide)sréticulés de 70 à 95 % a ainsi été réalisée. A partir de cespremières synthèses, 10 nouveaux poly(aminobismaléimide)sont été élaborés. Pour 9 d’entre eux, des diamines aromatiquesont été utilisées et, pour le dernier, une diamine siloxane. Cesrésultats démontrent la possibilité de généraliser ce procédé desynthèse.Dans un second temps, des poly(bismaléimide)s ont étésynthétisés, toujours sans solvant. Pour cela, les synthèses dequatre nouveaux bismaléimides liquides à température ambianteont été mises au point. Ces composés ont une structurealiphatique ou siloxane dans laquelle un motif pyroméllitique aété, ou pas, introduit. Leur polymérisation amorcée avecl’amorceur radicalaire ad hoc, conduit à la formation desmatériaux sans l’usage de solvant.Selon le choix des réactifs, des matériaux thermodurcissablesou élastomères sont obtenus. Ces derniers semblent mieuxadaptés à l’application souhaitée car, d’une part, la faibleviscosité des mélanges réactionnels permet leur applicationsans difficulté dans un module de puissance et, d’autre part, leurcaractère hydrophobe est plus marqué. L’un d’eux présente unestabilité thermique à 250 °C particulièrement intéressante et unetempérature de relaxation mécanique quasi hors gamme detempérature de fonctionnement. Ce matériau peut doncvraisemblablement être utilisé comme encapsulant. / The aim of this work is to develop new hydrophobicpolymeric materials for the protection of semi-conductorcomponents. These materials must withstand high temperature,strong electric fields and aggressive atmospheres such asmoisture. In this context, addition polyimides emerged as themost suitable polymers for the intended application. Thesynthesis of the encapsulant being made directly in the powermodules, it must be solvent free. Thus, we have developed newsolvent free synthesis routes of poly(aminobismaleimide)s andpoly(bismaleimide)s.First of all, different aliphatic diamines were used as a reactivesolvent in the synthesis of poly(aminobismaleimide)s to atemperature well below the melting point of the usedbismaleimide (m.p. > 300 °C). A first series of 3 newpoly(aminobismaleimide)s, crosslinked from 70 to 95 %, hasthus been made. From these first syntheses, 10 newpoly(aminobismaleimide)s have been developed. For 9 of them,aromatic diamines were used and, for the latter, a siloxanediamine. These results demonstrate that this process can begeneralized.Secondly, poly(bismaleimide)s were synthesized, still withoutany solvent. In order to do so, the syntheses of four newbismaleimides, liquid at room temperature, have beendeveloped. These compounds have an aliphatic or siloxanestructure in which a pyromellitic pattern has been or notintroduced. Their polymerization initiated with the suitable radicalinitiator leads to the formation of materials without the use of anysolvent.Depending on the choice of reagents, thermosetting materials orelastomers are obtained. These latter seem more suitable for thedesired application because, on one hand, the low viscosity ofthe reaction mixtures enables their application in a powermodule without any difficulty and, on the other hand, theirhydrophobic behaviour is stronger. One of them has aparticularly attractive thermal stability at 250 ° C and amechanical relaxation temperature almost out of the workingtemperature range. Therefore, this material may be used asencapsulant.

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第21472号 / エネ博第377号 / 新制||エネ||74(附属図書館) / 京都大学大学院エネルギー科学研究科エネルギー変換科学専攻 / (主査)准教授 増田 開, 教授 長﨑 百伸, 教授 大垣 英明 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

No description available.

Polymer matrices are commonly used as guest-host systems for organic chromophores for use in non-linear optical materials. The chromophores must be aligned or poled in an electric field in order to impart anisotropy and non-linear activity to the material. This poling process raises several issues, the two largest being the eventual relaxation of the chromophores back into random orientations due to brownian motion, and high molecular weight polymer matrices limiting chromophore mobility during poling. The prevention of this relaxation process is an area of significant interest, especially in applications that require long term coating stability and activity. In this study, a polymer matrix is synthesized that seeks to solve both of these problems with one system. The ideal system would be one that allows for chromophore mobility during processing, but once chromophores have reached the desired orientation, limits mobility and relaxation during in-service usage. A copolymer of methyl methacrylate and a Diels-Alder adduct cross-linking monomer was synthesized in order to meet these challenges. This polymer was blended with commercially available acrylic polymer and organic chromophore molecules in order to test the viability of the solution. It was found that at the percent composition of cross-linker being utilized in the study, the Diels-Alder linkages were not reforming in any measurable amount due to the low amount of Diels-Alder active monomer units. This led to the development of a new system based on mixing polyfuran based polymers with polymaleimide based polymers during processing. This method allows for high amounts of cross-linking after processing ceases, which achieves both initial goals of the project, as well as allowing facile synthesis of the desired polymer components. Another attempt to address these issues in polymer matrix formation led to the use of a novel inimer system. The cross-linking agent was also the polymerization initiator, and these functionalities were separated by a Diels-Alder linkage that would fall apart upon exposure to thermal stimulus. These polymers were synthesized and isolated easily, although in some cases gelation occurred. In order to observe the extent of the cross-linking inimer being incorporated into the matrix, cleavage experiments were performed to induce the breaking of the Diels-Alder adduct. Analyzing the Diels-Alder cleaved polymer led to an interesting result: all polymers showed an increase in apparent molecular weight when analyzed by gel permeation chromatography. The increase in molecular weight occurring upon cleavage of main chain bonds has never before been observed in literature. The explanation proposed was that the polymer adopted a "ropeball" like topology consisting of tightly coiled loops and knots. Upon cleavage of the cross-links, the ropeball was able to unwind into a much more linear topology, occupying a much larger hydrodynamic volume. This increase in hydrodynamic volume would cause the gel permeation chromatography results to show an apparent increase in molecular weight.

Разработаны алгоритмы расчета температурных полей и оценки термонапряженного состояния массивных железобетонных фундаментов в стадии охлаждения. / Algorithms for calculating temperature fields and assessing the thermally stressed state of massive reinforced concrete foundations in the cooling stage have been developed.