abstract: In nature, it is commonly observed that animals and birds perform movement-based thermoregulation activities to regulate their body temperatures. For example, flapping of elephant ears or plumage fluffing in birds. Taking inspiration from nature and to explore the possibilities of such heat transfer enhancements, augmentation of heat transfer rates induced by the vibration of solid and well as novel flexible pinned heatsinks were studied in this research project. Enhancement of natural convection has always been very important in improving the performance of the cooling mechanisms. In this research, flexible heatsinks were developed and they were characterized based on natural convection cooling with moderately vibrating conditions. The vibration of heated surfaces such as motor surfaces, condenser surfaces, robotic arms and exoskeletons led to the motivation of the development of heat sinks having flexible fins with an improved heat transfer capacity. The performance of an inflexible, solid copper pin fin heat sink was considered as the baseline, current industry standard for the thermal performance. It is expected to obtain maximum convective heat transfer at the resonance frequency of the flexible pin fins. Current experimental results with fixed input frequency and varying amplitudes indicate that the vibration provides a moderate improvement in convective heat transfer, however, the flexibility of fins had negligible effects. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2019

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Meteorology, 1979. / Microfiche copy available in Archives and Science. / Bibliography: leaves 86-88. / by Dawna Lisa Paton. / M.S.

According to the Intergovernmental Panel on Climate Change, Carbon Dioxide Removal (CDR) technologies play a significant role in deep mitigation pathways to limit global temperature rise to 1.5°C. As a result, interest in them is becoming increasingly prevalent, the most widely discussed being Direct Air Capture (DAC), or active removal of carbon dioxide from atmospheric air. While DAC processes have indeed been successfully tested, one of the most prominent being that developed by Canadian company Carbon Engineering, their widespread deployment faces significant headwinds due to prohibitively high energy consumption and its associated costs. Before DAC can be considered to exist in a state of technological readiness, reductions to the installations' energy demand must be realized. This thesis analyzes the thermodynamic behavior of Carbon Engineering's proposed 1 Mt-CO2/year natural gas fuelled DAC plant, which they describe as “a low-risk starting point rather than a fully optimized least-cost design” [Keith et al., Joule 2, 1573], with the aim to illustrate key areas to which energy efficiency improvement measures must target. With an understanding built of the mechanisms by which energy is utilized and irreversibly lost within their plant, suggestions are put forth for directions to pursue for process improvements, with further analysis included on potential alternative plant configurations which would reduce overall heat and power consumption. A thermodynamic work loss analysis is performed on their plant design at a system level, which finds 92.2% of incoming exergy being lost to thermodynamic irreversibilities. A component-level analysis is then performed to detail the mechanisms by which these losses occur in the most energy-intensive plant segments, namely, the calciner and preheat cyclones, air separation unit, water knockout system, CO2 compression system, and power island. The dissipation of chemical exergy in the air contactor component, i.e., the release of stored chemical exergy as low-grade heat to the environment due to the exothermic reaction of CO2 and aqueous KOH, was determined as the largest unavoidable source of work loss. The most avoidable losses were found to be associated with use of natural gas as a feedstock for heat and power, namely, through its introduction of additional CO2 and water to be processed within the plant, and due to gas turbine power production's inherent Carnot efficiency limits. Additional analysis and discussion follows regarding possible loss reduction measures and modifications, the key concept presented being the use of renewable energy to provide plant power, combined with a calciner using electric resistance heating to meet its reduced thermal demand. Use of a readily-available high-temperature heat source for calciner heat is also considered, with thorough description included of its thermodynamic advantages. Finally, the all-electric plant concept is analyzed at a system level, and its advantages compared to the original natural gas fuelled case. / Graduate

Diploma thesis deals with the problem of refrigerant cooling needs for air conditioning systems of buildings. Summary focuses on the theoretical basics and the physical nature of refrigeration and air conditioning technology. The consequences of split unite on microclimate in the room was experimentally tested and simultaneously investigated happenings associated to its activity. The aim is to unify the theoretical and experimentally obtained facts and apply them in the designing of air conditioning units. Design of air conditioning systems builds on my bachelor thesis, "Hot-air heating of gym", which subject was the ventilation system of gym.

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第19092号 / エネ博第316号 / 新制||エネ||64(附属図書館) / 32043 / 京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻 / (主査)教授 木下 正弘, 教授 森井 孝, 教授 片平 正人 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20710号 / 工博第4407号 / 新制||工||1685(附属図書館) / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 古賀 毅, 教授 吉崎 武尚, 教授 竹中 幹人 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21104号 / 工博第4468号 / 新制||工||1694(附属図書館) / 京都大学大学院工学研究科材料工学専攻 / (主査)教授 杉村 博之, 教授 田中 功, 准教授 野瀬 嘉太郎 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21464号 / 工博第4539号 / 新制||工||1708(附属図書館) / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 古賀 毅, 教授 吉崎 武尚, 教授 竹中 幹人 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

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Five systems consisting of different sorbate-sorbent combinations were studied using experimental volumetric adsorption techniques. Multiple adsorption isotherms were measured at low temperatures and low pressures for all of the systems studied which included CO2 adsorption on single walled carbon nanotubes (CO2 – SWCNT), Ethane adsorption on closed carbon nanohorns (Ethane-cNH), Ar adsorption on open carbon nanohorns (Ar – oNH), CO2 adsorption on zeolitic imidazolate framework-8 (CO2 – ZIF-8), and O2 adsorption on ZIF-8 (O2 – ZIF-8). Each of these systems offers a unique study of the relationship between the physical properties of the adsorbate and substrate and the effects of these properties on the thermodynamics and kinetics of adsorption. In addition to being of fundamental interest, the thermodynamics and kinetics of adsorption are important to understand for practical considerations in research fields such as gas storage and gas separation via adsorption processes, among other applications. CO2 – SWCNT is a system with a small linear molecular adsorbate with a permanent quadrupole moment adsorbing on a substrate with quasi-1D grooves and convex outer adsorption sites. Ethane-cNH is a system with a linear alkane adsorbing on a substrate with conical pores and convex outer adsorption sites. Ar – oNH is a system with a spherical atom sorbing in a substrate with two different groups of conical adsorption sites and both convex and concave surface sites. CO2 – ZIF-8 and O2 – ZIF-8 are both systems with small linear molecules sorbing in a flexible microporous scaffold-like substrate. Adsorption isotherms were analyzed to identify features corresponding to adsorbate-adsorbate and adsorbate-substrate interactions. Namely, the presence of substeps in the semi-logarithmic data were identified and interpreted to correspond to groups of adsorption sites of similar binding energy which likely depend on the morphology and/or structural flexibility of the substrates. All of the systems, with the exception of CO2 - SWCNTs, yielded at least some isotherms with substeps at pressures below that corresponding to saturation. Effective specific surface areas for all adsorbent-substrate combinations were calculated using the BET and Point-B methods for the sake of comparison. These surface area measurements are very dependent on the porosity and morphology of the substrate as well as the size and shape of the adsorbate atoms/molecules and therefore the values vary greatly between the different systems. The isosteric heat of adsorption was calculated using isotherms over the full range of temperatures for each system. A variant of the Clausius-Clapeyron equation was used for this purpose and the results were analyzed based on adsorbate-adsorbate and adsorbate-substrate interactions. Plateaus in the isosteric heat data for Ethane – cNH and Ar – oNH were related to the morphology of the substrates and properties of the adsorbate species. For CO2 – SWCNTs, the isosteric heat at all but the lowest coverages is below the latent heat of deposition. This is due to the quadrupole moment of CO2. For both of the studies of adsorption on ZIF-8, the isosteric heat contains peaks in the data which likely are the result of the flexibility of the ZIF-8 structure. The kinetics of adsorption (or, the rates at which the adsorption systems approach equilibrium) were analyzed as functions of isotherm temperature and coverage, vapor pressure, and fractional uptake point by point along individual isotherms using the linear driving force model. Certain trends in the kinetics of adsorption are consistent for all the systems studied and others vary depending on the specific adsorbate-substrate combination. As with the thermodynamic results, trends in the kinetics of adsorption are discussed in terms of the effects of adsorbate-adsorbate and adsorbate-substrate interactions.