Добірка наукової літератури з теми "Thermal blankets"

Using tetraethoxysilane (TEOS) as the source of silica, fibre reinforced silica aerogels were synthesized via fast ambient pressure drying using methanol (MeOH), trimethylchlorosilane (TMCS), ammonium fluoride (NH4F), and hexane. The molar ratio of TEOS/MeOH/(COOH)2/NH4F was kept constant at 1 : 38 : 3.73 × 10−5 : 0.023 and the gel was allowed to form inside the highly porous meta-aramid fibrous batting. The wet gel surface was chemically modified (silylation process) using various concentrations of TMCS in hexane in the range of 1 to 20% by volume. The fibre reinforced silica aerogel blanket was obtained subsequently through atmospheric pressure drying. The aerogel blanket samples were characterized by density, thermal conductivity, hydrophobicity (contact angle), and Scanning Electron Microscopy. The radiant heat resistance of the aerogel blankets was examined and compared with nonaerogel blankets. It has been observed that, compared to the ordinary nonaerogel blankets, the aerogel blankets showed a 58% increase in the estimated burn injury time and thus ensure a much better protection from heat and fire hazards. The effect of varying the concentration of TMCS on the estimated protection time has been examined. The improved thermal stability and the superior thermal insulation of the flexible aerogel blankets lead to applications being used for occupations that involve exposure to hazards of thermal radiation.

Hypothermia is a common complication in patients undergoing surgery under general anesthesia. It has been noted that, during the first hour of surgery, the patient’s internal temperature (Tcore) decreases by 0.5–1.5°C due to the vasodilatory effect of anesthetic gases, which affect the body’s thermoregulatory system by inhibiting vasoconstriction. Thus a continuous check on patient temperature must be carried out. The currently most used methods to avoid hypothermia are based on passive systems (such as blankets reducing body heat loss) and on active ones (thermal blankets, electric or hot-water mattresses, forced hot air, warming lamps, etc.). Within a broader research upon the environmental conditions, pollution, heat stress, and hypothermia risk in operating theatres, the authors set up an experimental investigation by using a warming blanket chosen from several types on sale. Their aim was to identify times and ways the human body reacts to the heat flowing from the blanket and the blanket’s effect on the average temperatureTskinand, as a consequence, onTcoretemperature of the patient. The here proposed methodology could allow surgeons to fix in advance the thermal power to supply through a warming blanket for reaching, in a prescribed time, the desired body temperature starting from a given state of hypothermia.

BACKGROUND: Cardiac surgical patients who require hypothermic cardiopulmonary bypass experience hypothermia, normothermia, and hyperthermia during the early postoperative period. Research-based rewarming protocols are needed to manage temperature variations. OBJECTIVE: To describe the effect of a standardized rewarming protocol and acetaminophen on the following outcome variables: core temperature, peak core temperature, rewarming time, and hyperthermia. METHODS: Patients (N = 60) were rewarmed using a standardized rewarming protocol. Electric heating blankets were used for subjects with core temperatures less than 36 degrees C on admission to the intensive care unit; other subjects were covered with cotton bath blankets. Subjects were also assigned to one of three acetaminophen groups (650 mg at 38.1 degrees C, 650 mg at 37 degrees C, 1300 mg at 37 degrees C). RESULTS: Using the protocol, subjects warmed to normothermia in 3.6 to 6 hours. The 16-hour core temperature thermal curves of heating blanket versus cotton bath blanket subjects differed significantly; thermal curves of the acetaminophen groups were similar. Peak core temperature was significantly lower in heating blanket subjects and unaffected by acetaminophen group. The onset of hyperthermia was not significantly affected by the method of rewarming (electric heating blanket versus cotton blankets) or acetaminophen group. Rewarming time was significantly longer for electric heating blanket subjects. CONCLUSIONS: Our results indicate that mildly hypothermic subjects rewarmed with electric heating blankets during the early postoperative period have lower peak core temperatures and longer rewarming times than those rewarmed with cotton bath blankets. Acetaminophen administration at normothermia does not significantly affect peak core temperature or the onset of hyperthermia.

Purpose The purpose of this paper is fourfold: to experimentally determine the standby thermal energy losses in various hot water cylinders in both scenarios, without isotherm blanket installation and with isotherm blanket installation; to analytically evaluate the performance of either the geyser, split- or integrated-type ASHP water heaters based on the number of heating up cycles and total electrical energy consumptions over a 24-h period without isotherm blankets and with isotherm blankets installed; to demonstrate the impact of the electrical energy factors of the split- and integrated-type ASHP water heaters under both the scenarios (without and with the isotherm blankets installed); and to use statistical tests (one way ANOVA and multiple comparison procedure tests) to verify whether any significant difference in the standby thermal energy losses occurred for each of the heating devices under both the scenarios. Design/methodology/approach The methodology was divided into monitoring of the performance of the electrical energy consumptions and ambient conditions of the hot water heating technologies without isotherm blanket installation and with isotherm blanket installation. Findings The results reveal that the average standby thermal energy loss of the geyser without the installation of an isotherm blanket was 2.5 kWh. And this standby loss can be reduced to over 18.5 per cent by just installing a 40-mm thick isotherm blanket on the tank. The statistical tests show a significant mean difference in the group electrical energy consumed to compensate for the standby losses under both scenarios. In contrast, the average standby thermal energy losses for the split- and integrated-type ASHP water heaters were 1.33 kWh and 0.92 kWh, respectively. There was a reduction of 15.5 per cent and 3.5 per cent in the electrical energy consumed in compensating for standby losses for both the split and integrated types, respectively, but there was no significant mean difference in the standby losses under both scenarios for the two systems. Again, without any loss of generality, the electrical energy factor of both the ASHP water heaters decreased upon installation of the isotherm blanks. Research limitations/implications The experiments were conducted only for a 150-L geyser and 150-L split- and integrated-type ASHP water heaters. The category of the different types of ASHP water heaters was limited to one because of the cost implication. Practical implications The experiments were not conducted with various hot water storage tanks installed in different positions (roof, inside or outside of a building wall, etc.) so that actual real-life observations could be obtained. The challenges of easy disassembling and deployment of systems and DAS to different positions were also a real concern. Social implications The findings can help homeowners and ESCO in deciding whether to install isotherm blankets on storage tanks of ASHP water heaters on the basis of the impact of standby losses and its potential viability. Originality/value The experimental design and methodology are the first of its kind to be conducted in South Africa. The results and interpretation were obtained from original data collected from a set of experiments conducted. The findings also show that the installation of isotherm blanket on an electric geyser can result in a significant mean reduction in the standby losses. In contrast, an installation of the isotherm blankets on the storage tanks of ASHP water heaters can reduce the standby losses, but there exists no significant mean difference.

Aerogel is among the best solid thermal insulators. Aerogel is a silica gel formed by supercritical extraction which results in a porous open cell solid insulation with a thermal conductivity as low as 0.013W∕mK. Aerogels have a wide range of uses such as insulation for windows, vehicles, refrigerators∕freezers, etc. Usage for aerogel can be extended for use where flexibility is needed, such as apparel, by embedding it into a polyester batting blanket. These aerogel blankets, although flexible, have little resistance to compression and experience a residual strain effect upon exposure to elevated pressures. It was suggested, by Aspen Aerogels Inc., that a prototype aerogel blanket would have increased resistance to compression and minimized residual strain upon exposure to elevated pressures. Samples of prototype and normal product-line aerogel insulating blankets were acquired. These materials were separately tested for thermal conductivity and compressive strain at incremental pressure stops up to 1.2MPa. The compressive strain of the prototype aerogel blanket reached a level of 0.25mm∕mm whereas the product-line aerogel blanket compressed to 0.48mm∕mm at 1.2MPa. Before compression, the thermal conductivity of the prototype aerogel blanket was slightly higher than the product-line aerogel blanket. During compression the thermal conductivity increased 46% for the product-line aerogel blanket whereas it increased only 13% for the prototype aerogel blanket at 1.2MPa. The total thermal resistance decreased 64% for the product-line aerogel blanket at 1.2MPa and remained at that value upon decompression to atmospheric pressure. The total thermal resistance of the prototype aerogel blanket decreased 33% at 1.2MPa and returned to within 1% of its initial value upon decompression to atmospheric pressure. It was found that the prototype aerogel blanket has approximately twice as much resistance to hydrostatic compression to a pressure of 1.2MPa and also recovers to its original state upon decompression. The thermal resistance of the prototype aerogel blanket remained 37% higher than the product-line aerogel blanket at 1.2MPa. This resistance to compression and the ability to recover to its original state upon decompression from elevated pressures makes the prototype aerogel blanket suitable for applications where high insulation, resistance to compression, and recovery after a compression cycle is needed.

It is known that aerogel impregnated fibrous blankets offer high acoustic absorption and thermal insulation performance. These materials are becoming very popular in various industrial and building applications. Although the reasons for the high thermal insulation performance of these materials are well understood, it is still largely unclear what controls their acoustic performance. Additionally, only a small number of publications to date report on the acoustical properties of fibrous blankets impregnated with powder aerogels. There is a lack of studies that attempt to explain the measured absorption properties with a valid mathematical model. This paper contributes to this knowledge gap through a simulation that predicts the measured complex acoustic reflection coefficient of aerogel blankets with different filling ratios. It is shown that the acoustic performance of a fibrous blanket impregnated with aerogel is generally controlled by the effective pore size and porosity of the composite structure. It is shown that there is a need for refinement of a classical Biot-type model to take into account the sorption and pressure diffusion effects, which become important with the increased filling ratio.

Aerogel blankets are composites of silica aerogel particles dispersed in a reinforcing fiber matrix that turns the brittle aerogel into durable and flexible insulating materials. In this study, silica aerogel was loaded on glass wool with different concentrations (0–18.6%) and morphological and thermal characteristics of the aerogel blankets were studied. Rate of modified blanket decomposition was slower at temperatures between 250°C and 650°C due to the retardant effect of the silica aerogel. The average diameter of the fiber for either original glass wool or modified glass wool materials was approximately 20 μm and samples had porous, interconnected particles with dendritic-like structure.

The China Fusion Engineering Test Reactor (CFETR) is a tokamak device to validate and demonstrate fusion engineering technology. In CFETR, the breeding blanket is a vital important component that is closely related to the performance and safety of the fusion reactor. Neutronics/thermal-hydraulics (N/TH) coupling effect is significant in the numerical analysis of the fission reactor. However, in the numerical analysis of the fusion reactor, the existing coupling code system mostly adopts the one-way coupling method. The ignorance of the two-way N/TH coupling effect would lead to inaccurate results. In this paper, the MCNP/FLUENT code system is developed based on the 3D-1D-2D hybrid coupling method. The one-way and two-way N/TH coupling calculations for two typical blanket concepts, the helium-cooled solid breeder (HCSB) blanket and the water-cooled ceramic breeder (WCCB) blanket, are carried out to study the two-way N/TH coupling effect in CFETR. The numerical results show that, compared with the results from the one-way N/TH coupling calculation, the tritium breeding ration (TBR) calculated with the two-way N/TH calculation decreases by −0.11% and increases by 4.45% for the HCSB and WCCB blankets, respectively. The maximum temperature increases by 1 °C and 29 °C for the HCSB and WCCB blankets, respectively.

Nowadays, the usage of thermal insulation materials is widespread not only in the building sector but also in the vehicle industry. The application of fibrous or loose-fill insulation materials like glass wool or mineral wool as well as aerogel is well known. Aerogel-based materials are among the best solid materials for thermal insulation available today; they are prepared through a sol–gel process. For building walls, the glass-fiber-enhanced types are the frequently used ones. They are prepared by adding the liquid–solid solution to the fibrous batting, which is called a sol–gel process. In the present paper, the changes in the most important building physical properties of aerogel blankets after thermal annealing are presented. The samples were subjected to isochronal heat treatments from 70 to 210 °C for 24 h. The changes in the thermal conductivity were followed by Holometrix Lambda heat flow meter, and differential scanning calorimetry results were also recorded. From the measured values, together with the densities, the most important thermal properties were calculated, such as thermal resistance, diffusivity, effusivity (heat absorption), and thermal inertia. In this paper, we attempt to clarify the role played by thermal annealing in the transient thermal properties of aerogel materials. Besides presenting the measurement results, a theoretical background is given. The investigations of not only the steady-state but also the transient thermal parameters of the materials are momentous at the design stage.

En Europe, le secteur du bâtiment est le plus énergivore et représente environ 40 % de l’énergie totale consommée. A court terme, la façon la plus efficace de baisser cette consommation est de réduire les déperditions thermiques à travers l’enveloppe du bâtiment en augmentant son isolation thermique, tout en minimisant la perte de surface habitable. Dans ce contexte, les travaux de thèse portent sur l’étude et la mise au point pour pré-industrialisation de matériaux super-isolants composites à base d'aérogel de silice. Le matériau composite étudié fait partie de la famille des blankets aérogels et est obtenu via un procédé de séchage ambiant innovant. Grâce à leur faible conductivité thermique et leurs propriétés mécaniques renforcées, les blankets aérogels sont d’un grand intérêt pour l’isolation thermique qui nécessite de fines épaisseurs d’isolants. Les travaux de thèse visent dans un premier temps à effectuer une analyse des propriétés thermophysiques des blankets aérogels étudiés à la sortie du moule de fabrication et vis-à-vis de leur mise en œuvre lorsqu’ils sont soumis à différentes sollicitations (mécaniques, hygriques ...). Des travaux de modélisation du transfert de chaleur dans le blanket aérogel sont développés afin d’étudier les relations entre le transfert thermique et les paramètres morphologiques du matériau. Dans un second temps, les travaux de thèse portent sur l’étude des performances à attendre d’un système d’isolation basé sur le blanket aérogel mis en œuvre sur un bâtiment, à la fois par l’analyse du comportement thermique d’une cellule test en climat réel, ainsi que par la conduite de simulations numériques de bâtiments prenant en compte plusieurs techniques constructives, configurations de murs, et ce, pour plusieurs climats européens. Les résultats obtenus montrent que les blankets aérogels étudiés ont une très faible conductivité thermique –0,016 W.m-1.K-1– et ont un fort potentiel d’application dans l’isolation thermique du bâtiment
Buildings are the largest energy end-use sector and account for about 40 % of the total final energy consumption in the EU-28. A short-term strategy to efficiently reduce this consumption is to decrease thermal losses through the building envelope by improving its thermal insulation, while minimizing the reduction of the available indoor living space. In this context, the thesis deals with the study and development for pre-industrialization of super-insulating composite materials based on silica aerogel. The studied material is part of the aerogel blanket family and is obtained by an innovative ambient drying process. With a very low thermal conductivity and reinforced mechanical properties, aerogel blankets are of great interest for applications where they can offer a cost advantage due to a space-saving effect. Firstly, the thesis work aims at performing analyses of the thermo-physical properties of the studied aerogel blankets at the exit of the molding and drying processes, and during application, when they are subjected to different environmental stresses (mechanical, hygric …). Heat transfer modeling is developed to study the relationship between the morphological parameters of the material and thermal transfer within it. Secondly, the thesis work focuses on the study of the expected performances of an insulating system based on the aerogel blanket, by the study of the thermal behavior of an experimental building monitored under actual climate, as well as the use of whole building energy numerical simulations taking into account several constructive techniques, different wall configurations, for various European climates. The results obtained show that the aerogel blankets studied have a thermal conductivity as low as 0.016 W.m-1.K-1 and have promising applications for building thermal insulation needs

The Breeding Blanket is an essential component of the DEMO fusion reactor and its design is one of the pivotal purposes of the DEMO project. Indeed, this component has to withstand severe operating conditions, as it is directly exposed to the plasma, making its design particularly challenging. In particular, the Water-Cooled Lithium-Lead (WCLL) BB concept is one of the candidates currently considered for the conceptual design of the European DEMO reactor. The development of a robust BB system is crucial for the design of the whole DEMO reactor and the thermo-mechanical assessment of the whole BB segments is mandatory to allow checking their structural performances in different loading scenarios. In this dissertation, a multi-scale procedure, allowing to investigate in detail the thermo-mechanical performances of an entire blanket segment, is proposed. In particular, the Central Outboard Blanket (COB) segment has been considered and the results are herewith presented. The structural performances have been investigated in view of the RCC-MRx design criteria.

Обґрунтовано доцільність використання вакуумного сушіння в технологічних процесах формостворення верху взуття з термолабільних матеріалів.
The expediency of using vacuum drying in technological processes of forming of shoe upper from thermo labile materials is substantiated.

One of the key components of a nuclear fusion power plant is the Breeding Blanket (BB), in charge of ensuring the essential functions of Tritium production, shield the Vacuum Vessel (VV) and remove the heat generated in the toroidal chamber. Two conceptual designs are currently being studied for the implementation in the DEMOnstration Fusion Reactor (DEMO) in the framework of R&D activities under the coordination of the EUROfusion Consortium. One of these two BB is the Water-Cooled Lithium-Lead (WCLL), which relies on two different fluid: the water, necessary to remove the generated heat in the tokamak and to shield the vacuum vessel from neutrons, and the Lithium-Lead (PbLi) eutectic alloy, adopted as breeder and neutron multiplier, necessary for the Tritium production in order to make the fusion self-sustaining. The first function is fulfilled by two independent cooling systems: the First Wall (FW), that facing the plasma removes the heat flux raised from it, and the Breeding Zone (BZ), that removes the deposited power due to neutron and photon interaction inside the breeder. To guarantee good energy conversion efficiencies, these two systems must operate under certain conditions, and pressurized water at the typical pressure of the nuclear Pressurized Water Reactor (PWR) is adopted. The Ph.D. work has been developed in collaboration with ENEA Brasimone Research Center, under the coordination of the EUROfusion Consortium in the task of the Work Package Breeding Blanket. The aim of this Ph.D. thesis is to contribute to the development of the conceptual design of the WCLL breeding blanket, in order to design an efficient and reliable system, demonstrating the capability to fully withstands the DEMO requirements in normal and off-normal conditions. The activity has been focused on the thermal-hydraulic of the system; specifically, the analyses were performed on one single elementary cell, that compose the WCLL due to its periodicity. To perform realistic analyses, multiple factors have taken into account: engineering aspects, neutronic and thermo-mechanic. This has been pursued through the engineering approach and with the application of the numerical CFD code to represent the behaviors of the different analyzed models. The first part of this study (Chapter 3) starts from the WCLL design review, which is described in Section 3.1. This section concerns the previously studied and developed configurations of the WCLL. Four different configurations (T01.A, T01.B, T02 and T03) have been studied in a comparative analysis, evaluating the main advantages and issues, that have led to the development of the WCLL 2018 V0.2 configuration. The WCLL 2018 V0.2 is the starting point of this research activity. The elementary cell is fully described in Section 3.2, where all the components have been expounded, concluding the introductory part of this Ph.D. work. Subsequently, in Chapter 4, different thermal-hydraulic analyses have been performed through numerical simulations, where a complete three-dimensional finite volume model of the WCLL elementary cell has been set-up in each analysis, using the commercial CFD code ANSYS CFX v18.2. Several steady-state analyses have been performed in order to optimize the BZ tubes layout, the FW cooling system, the BZ manifold layout and to evaluate the impact of the heat transfer modelling approach through the PbLi modelling and its properties. Once the CAD has been defined, the thermal power and the related cooling systems, FW and BZ, have been set through an analytical approach, in order to guarantee compliance with the main DEMO requirements design. The numerical model includes fluid and solid domains, representing in detail the WCLL elementary cell with its different structures and fluids. The Section 4.3 has the aim of optimizing the arrangement of the BZ pipes, guaranteeing a Eurofer temperature below the imposed limit of 550°C, and water at certain conditions in compliance with the thermodynamic cycle assumed for the electricity production. Several configurations have been analyzed to identify a promising BZ coolant system layout, which satisfies the DEMO requirements. The CFD analyses have been carried out investigating the temperature field of the solid structures, Eurofer and Tungsten, and also the thermal-hydraulic performances of the water-cooling systems and PbLi. These optimization analyses led to the V0.6 configuration, which has set the minimum number of BZ tubes to 22 and ensuring a symmetric temperature field in the toroidal direction in the BZ and FW systems and concerning the FW also in poloidal direction, a maximum temperature of the Eurofer structures of around 500°C, which not exceeds the imposed limit of 550°C. In the next paragraph, the Section 4.4, a FW water channels optimization has been achieved, reducing the channels number from 10 up to 4. This channels reduction has been pursued thanks to the fact that the FW temperature was considerably below the imposed limit of 550°C, and to a DEMO's thermal load review that has led to a modification on the imposed heat flux on the FW from 0.5 MW/m2 to 0.32 MW/m2. The optimization has returned a greater homogeneity of the temperature field between BZ and FW systems, reducing the passive heat removal of the FW system from the BZ system. Although the pressure drops strongly increase, it has resulted in a decrease in the volume of water present in the first centimeters of the cell which positively affects the Tritium Breeding Ratio (TBR), the fundamental parameter for the Tritium production. The V0.6 configuration with 4 water channels (named V0.6_FW4), fully withstands the DEMO thermal loads not exceeding the Eurofer temperature limit of 550°C. Another important parameter that has been affected by this reduction is the FW water velocity that has been strongly increased, enhancing the water thermal-hydraulic performances. In Section 4.5, the results from the analysis of the V0.6_FW4_R model have highlighted that the recirculation manifold have to be adopted to guarantee large and safety margins from a thermal crisis. The recirculation ensures a lower wall temperature in all the BZ tubes, especially in the tubes near the FW which are subjected to greater power deposition. In addition, a greater flow of water flow rate, guarantee a large and safety margin from the possibility of thermal crisis. The second part of the activity, reported in Section 4.6, concerns the assessment of the assumption made in the numerical model development. Since the PbLi thermal conductivity deeply affects the elementary cell temperature field, due to its huge thermal inertia, a study was also conducted on it. Two different PbLi thermal conductivity have been chosen to evaluate the temperature field of the cell, the suggested Mogahed correlation and the conservative IAEA correlation. The analyses have also been performed with the PbLi domain set as liquid and solid, evaluating the impact of this assumption on the numerical prediction. It has been evaluated that the PbLi modelling approach does not affect the results, increasing the temperature field by only a few degrees in the model with solid PbLi. In addition, simulations with liquid PbLi in forced convection and absence of buoyancy forces and magneto-hydrodynamics effects, have demonstrated that the convective contribution to the heat exchange is actually negligible. The PbLi has, in both cases with forced convection and in the absence of buoyancy effects, a laminar flow. Moreover, to evaluate the liquid metal behavior the Prandtl number has been analytically evaluated. The dimensionless number has shown that the thermal diffusivity, which is related to the rate of heat transfer by conduction, unambiguously dominates prevailing on convection, that can be neglected. Instead, what significantly affects the model is the adopted PbLi thermal conductivity correlation, that with the IAEA causes the Eurofer temperature limit to be exceeded and the hot-spots onset. Due to the choice of setting as reference property, for the PbLi thermal conductivity, the IAEA correlation, the analyses on the updated configuration returns an Eurofer temperature field which exceeds the imposed Eurofer temperature limits in different areas. The analyses, reported in Section 4.7, have led to a further set of simulations to find out a BZ tubes layout in order to guarantee the respects of the requirements, even in the worst conservative conditions. The second BZ optimization has carried out an alternative BZ tubes disposal, which has resulted in a configuration named WCLL 2018 V0.6_B. These modifications have not led to major changes in the BZ water domain, keeping almost unchanged the relevant thermal-hydraulic parameters, as velocity, pressure drops and temperature. However, they have involved the PbLi and structures temperature field reaching a Eurofer temperature slightly below the imposed limit of 550°C, extinguishing the structures hot-spots. The V0.6_B has been chosen as final configuration, able to cope with the operative DEMO thermal loads, guaranteeing the respect of the DEMO Eurofer temperature limit and its related requirements. The last part of this work (Chapter 5) has been focused on the operational phases of the WCLL breeding blanket. One of the main functions of the BB is the conversions of the thermal energy from the fusion reaction in energy suitable for the power generation. The pulsed nature of the DEMO fusion reactor divides the operative phase in two main phases: pulse where the Deuterium and Tritium are burnt and energy is produced for 120 min, and dwell estimated to be 10 min where the central solenoid is recharging, and decay heat is removed. This research activity has been pursued to verify if the selected V0.6_B design is able to face the DEMO operational phases, investigating the response of the systems from the thermal-hydraulic point of view. In Section 5.1, a three-dimensional model has been reproduced according to the main outcomes of the previous Chapter. Different CFD transient analyses have been performed to verify if the selected design is suitable with the DEMO constrains and requirements, investigating different thermal behaviors. Transient thermal-hydraulic analyses have been set-up to simulate the burning phase, composed by ramp-up and ramp-down, after which steady state conditions of full power and dwell are reached respectively. Moreover, power fluctuation analyses have been performed to investigate the plasma instabilities caused by the pellets injection during the normal operation, this causes peaks of over or under power. In addition, a further analysis focused on the evaluation of the effect of the PbLi thermal inertia has been performed. This analysis it does not represent any realistic behavior of the reactor, as the previous ones, but it serves to investigate the ideal behavior that would occur in PbLi in case of constant cooling. Unfortunately, the transient analyses require a significantly higher computational cost, and this implies that in order to obtain results in a reasonable time, it is mandatory to reduce the number of elements in the numerical model. Although it is interesting to obtain extremely accurate output values of the model, the main goal of these analyses is to investigate the global performances of the cooling systems, therefore, in Section 5.2 a mesh sensitivity has been performed in order to reduce the high number of elements without losing accuracy in the obtained results. To perform the transient analyses different time-dependent thermal loads have been considered. The operational phases of DEMO have been characterized by different power contributions which vary in space and time. These thermal loads have been widely discussed in Section 5.3, identifying the power contribution curves to adopt for the model. In particular, in Section 5.4, the model solver settings and boundary conditions have been set-up per each run. In Section 5.5, the results have been described and differentiated by steady-state and transient analyses. The first part (Section 5.5.1) concerns the steady-state analyses performed to impose the initial conditions for the transient, and in the second part (Section 5.5.2), the transient analyses have been widely discussed. In particular, in sub-sections 5.5.2.1 and 5.5.2.2, the fast ramp-up and ramp-down phases are respectively analyzed. Both show how the PbLi thermal inertia plays a key role in the rise and fall of the temperature of the structures, ensuring to the systems a slowly gradual trend. The FW system promptly reacts to the power variation, showing a temperature trend similar to the power one. Instead, the BZ system slowly reacts to power variations. It depends on the PbLi thermal inertia, which strongly slows down the temperature trend, causing a considerable delay in reaching steady-state conditions. In both simulations, the Eurofer temperature is below the limit and the operative water constrains are respected and guaranteed. The study of the power fluctuations has been reported in sub-sections 5.5.2.3 and 5.5.2.4, where the V0.6_B layout has been subjected to different power oscillation. These analyses have been performed for the purpose of studying if the PbLi thermal inertia can mitigate these oscillations, continuing to operate within the required requirements. The thermal-hydraulic goal is that the elementary cell continues to supply water to the Primary Heat Transfer System (PHTS) at the required conditions for the electricity production. In addition, it has been highlighted that, in the remote case of an overpower peaks series, the huge PbLi thermal inertia absorbs these oscillations not provoking a temperature build-up. The same cannot be stated regarding the FW systems where a slight temperature build-up has been evidenced. In sub-section 5.5.2.5, an unrealistic study has been performed to evaluate the PbLi thermal inertia. The system has been subjected to a step-down ramp, passing from the nominal power to a zero-power condition. The analysis is aimed at identifying the characteristic time trend of both systems. A strong cooling time differentiation, between FW and BZ system, has been highlighted, where the cooling time of the PbLi has different order of magnitude compared with the FW. In conclusions, different numerical simulations have been performed to fully evaluate the thermal behavior of the WCLL elementary cell, within steady-state and transient analyses. The first part of the Ph.D. research activity has focused in the development of a WCLL elementary cell design that satisfies the DEMO requirements, optimizing the BZ tubes and the FW water channels. The analyses have led to choose a final design the V0.6_B layout, since it withstands the normal operative thermal loads. The second part, instead, has demonstrated that the selected design is able to withstand all the operational phases of the DEMO fusion reactor, confirming the choice made in the first part. The final design has been selected to comply with the DEMO requirements, withstanding the thermal loads, and guaranteeing adequate water conditions for the electricity production during all the reactor phases.

One of the greatest challenges facing the nuclear power industry is the final disposition of nuclear waste. To meet the needs of the nuclear power industry, a new fuel assembly design, called DUPLEX, has been developed which provides higher fuel burnups, burns transuranic waste while reducing minor actinides, reduces the long term radiotoxicity of spent nuclear fuel, and was developed for use in current light water reactors. The DUPLEX design considered in this thesis is based on a seed and blanket unit (SBU) configuration, where the seed region contains standard UO2 fuel, and the blanket region contains an inert matrix (Pu,Np,Am)O2-MgO-ZrO2 fuel. The research efforts of this thesis are first to consider the higher burnup effects on DUPLEX assembly thermal-hydraulic performance and thermal safety margin over the assembly’s expected operational lifetime. In order to accomplish this, an existing burnup-dependent thermal-hydraulic methodology for conventional homogeneous fuel assemblies has been updated to meet the modeling needs specific to SBU-type assemblies. The developed framework dramatically expands the capabilities of the latest thermal-hydraulic evaluation framework such that the most promising and unique DUPLEX fuel design can be evaluated. As part of this updated methodology, the posed DUPLEX design is evaluated with respect to the minimum departure from nucleate boiling ratio, peak fuel temperatures for both regions, and the peak cladding temperatures, under ANS Condition I, II, and III transient events with the thermal-hydraulic code VIPRE-01. Due to difficulty in the fabrication and handling of minor actinide dioxides, documented thermal conductivity values for the considered IMF design are unavailable. In order to develop a representative thermal conductivity model for use in VIPRE-01, an extensive literature survey on the thermal conductivity of (Pu,Np,Am)O2-MgO-ZrO2 component materials and a comprehensive review of combinatory models was performed. Using the updated methodology, VIPRE-01 is used to perform steady-state and transient thermal hydraulic analyses for the DUPLEX fuel assembly. During loss-of-flow accident scenarios, the DUPLEX design is shown to meet imposed safety criteria. However, using the most conservative thermal conductivity modeling approach for (Pu,Np,Am)O2-MgO-ZrO2, the blanket region fuel temperatures remain only slightly below the design limit.

碩士
國立成功大學
工業設計學系
103
With human development and advance of science and technology, bedding design has been attached much more importance. The thermal discomfort caused by the environmental temperature always disrupts human sleep. Considering the sleep thermal comfort, blanket design has the potential to alter the bedding microclimate to provide a comfortable sleeping environment. Hence, the purpose of this study was to propose an innovative blanket design to improve sleep thermal comfort and sleep quality through understanding the impact of thermoregulation, sleeping postures between humans and blanket and the changes of body temperature in each body segments on sleep. An innovative blanket has been proposed in this study. To begin with, the design criterion were set up by the discussion of the initial stage focus group. By discussion, the general problems caused sleep thermal discomfort were found and the ways people deal with the problems were discussed. Design principles for the blanket design proposed by this study were: (1) Avoid great differences in skin temperatures between the extremities and the torso; (2) Decrease the blanket movement. Preliminary design concepts were obtained by the second stage focus group and two main features were extracted. Based on the two design features and consideration of the thermal characteristics of different body segments, the final design was developed. An experimental evaluation was conducted to assess the efficacy of the designed blanket. Result showed that the proposed blanket had more capable of improving sleep thermal comfort and sleep quality. The results of this study clearly support the notion that sleep thermal comfort can be improved by the combination of different materials based on the thermal characteristics of each body segment.

The PhD activity discussed in this document was conducted between 2018 and 2021. It profited from a collaboration between the Department of Astronautical, Electrical and Energy Engineering (DIAEE) of Sapienza University of Rome and the Experimental Engineering Division of ENEA at Brasimone. Within the framework of EUROfusion Consortium research activity, the R&D efforts focused on the investigation of one principal blanket option for the European DEMOnstration Power Plant (EU-DEMO): the Water-Cooled Lead-Lithium (WCLL). For this concept, ENEA and its Italian related partners are the principal investigators. During last years, DIAEE played an important role in the conceptualization of the WCLL Breeding Blanket (BB) and its related primary cooling systems. In addition, an extended transient analysis was carried out to assess their thermal-hydraulic performances in both normal operations and accidental conditions. Such work was carried out involving research activities related to both International Thermonuclear Experimental Reactor (ITER) and EU-DEMO fusion power plant. This document is articulated in seven sections. The first one defines the PhD activity framework. In order to perform system-level transient analysis of tokamak reactors, a modified version of the thermal-hydraulic code RELAP5/Mod3.3 was developed at DIAEE in collaboration with ENEA. The aim is enhancing the code modelling capabilities with respect to fusion power plants. Section 2 is dedicated to discuss the implemented features. Sections 3 and 4 refer to the research activity involving DEMO WCLL. In § 3 the pre-conceptual design of the blanket component and related primary cooling circuits is described in detail. Their thermal-hydraulic model, developed for calculation purposes, is treated in § 4. The same section also reports the outcomes of the transient analysis. In the same way, § 5 and 6 are related to ITER WCLL-Test Blanket System (TBS) research activity. The TBS conceptual design, in particular the one of Water Cooling System (WCS) circuit whose DIAEE is responsible for, is described in § 5. To perform the system thermal-hydraulic assessment a dedicated model was developed. Its detailed description is provided in § 6, together with a full comment of the calculation results. Finally, § 7 focuses on the main conclusions and future perspectives of the work done. The first issue to be addressed was the development of a suitable code to perform the computational activity. System thermal-hydraulic codes are the reference numerical tools adopted for the nuclear reactor transient analysis. Most of them, such as RELAP5, were developed and validated to perform best-estimate transient simulations of Light Water Reactors (LWR). Once validated against experimental data coming from more than one-hundred facilities, they have been used throughout decades to perform the licensing of LWRs. Simulation results allowed to characterize the reactor transient behavior in the full range of operative and accidental conditions. The same approach to reactor transient analysis was envisaged also for fusion power plants. Although, existing system codes lack of some specific features required to properly simulate the fusion reactor performances. For this, during the last years, a modified version of the system code RELAP5/Mod3.3 was developed at DIAEE, including some new upgrades needed to address the modelling issues arising from the simulation of tokamak fusion reactors. New implementations consist in: i) lead-lithium (PbLi) and HITEC© working fluids, with their thermophysical properties; ii) new heat transfer correlations for liquid metals and molten salts; iii) helicoidally tubes dedicated heat transfer correlations and two-phase flow maps. The effectiveness of the new features introduced was verified throughout the three years of research activity by performing transient simulations involving tokamak reactors. Referring to the helicoidally geometry, the new two-phase flow maps were also tested against experimental data coming from OSU-MASLWR (Oregon State University - Multi Application Small Light Water Reactor) facility. In particular, a power manoeuvring test (named ICSP Test SP3) was selected for benchmarking purposes. Several power steps of the Fuel Pin Simulator, standing for the reactor core, was reproduced, from 80 to 320 kW. The aim of the experiment was to investigate the primary system natural circulation and secondary system superheating for a variety of core power levels and feedwater flow rates. The effects of the code modifications on the simulation outcomes were clearly visible at higher power levels when the heat transfer within the HCSG plays a more important role. Indeed, above a certain power threshold, nearly 200 kW, the default version showed limited capabilities to reproduce the test. On the contrary, the trends related to the modified version fit quite well the experimental data. Regarding the DEMO WCLL, in this document, it was presented the outcome of the pre-conceptual design developed during the just finished Horizon 2020 research programme. The design activity performed at DIAEE which the candidate took part to was mainly related to the BB Primary Heat Transfer System (PHTS) layout. The main system function is to remove the heat produced in the blanket components, delivering such thermal power to the Power Conversion System (PCS) to be converted into electricity. The BB PHTS is divided in two independent cooling systems, foreseen for the heat removal from the Breeder Zone (BZ) and the First Wall (FW). Both the BZ and the FW PHTSs consist of two cooling loops based on proven technologies extrapolated from Pressurized Water Reactors (PWR). Each primary system comprises the in-vacuum vessel cooling circuit, the ex-vacuum vessel equipment (pumps, heat exchangers/steam generators and a pressurizer), and the correspondent connecting lines. The BB PHTS is conceived in order to avoid a loop segregation. The BZ/FW PHTS cold legs feed the cold ring, which accomplishes the distribution of the cold water to each in- vacuum vessel cooling circuit (one per each sector). Primary coolant removes power from the blanket components and is collected in the hot ring that delivers water to the hot legs. In case of pump trip in a single PHTS loop, the other cooling loop guarantees the power removal from the whole system after the plasma shutdown. With the aim of the design improvement, system-level transient analyses were run involving the WCLL blanket component and related PHTS. The DIAEE version of RELAP5/Mod3.3 was used for this purpose. Such activity was related to EUROfusion Consortium Work Packages Breeding Blanket (WPBB) and Balance of Plant (WPBoP). Firstly, a full DEMO WCLL thermal-hydraulic model was prepared, considering the BoP Indirect Coupling Design option. Blanket was simulated using equivalent components characterized by lumped parameters. The BZ and FW PHTS circuits were modelled including all the components within and outside the vacuum vessel. PCS nodalization starts from the main feedwater line and arrives up to the Turbine Stop Valves. Thus, only the BZ Once Through Steam Generators (OTSG) secondary side was simulated. Regarding the Intermediate Heat Transfer System (IHTS), the same approach was adopted. Only the cold and hot legs upwards/downwards the FW Heat EXchangers (HEX) shell side were added to the input deck. PCS feedwater and IHTS molten salt conditions at the BZ OTSGs and FW HEXs secondary side inlet were provided by means of boundary conditions. The model developed was tested against the design data by simulating the full plasma power state. Beginning of Life conditions were considered. Proportional-Integral (PI) controllers were implemented to: i) regulate the primary pump rotational velocity and set the required value of the system flow; ii) control the PCS feedwater and IHTS molten salt mass flows in order to obtain the required PHTS water temperature at blanket inlet (i.e. OTSG outlet, 295 °C). Simulation results were in good agreement with the nominal values, demonstrating the appropriateness of the nodalization scheme prepared and of the control system implemented. Blanket and PHTS thermal-hydraulic performances in this flat-top power state were fully characterized, including the calculation of the system pressure drops and heat losses. Then, this steady-state calculation was used as initial condition to perform the DEMO WCLL transient analysis, including some operational and accidental transients. The DEMO reactor normal operations were simulated, including both pulse and dwell phases. Reference plasma ramp-down and ramp-up curves were adopted for simulations purposes. Primary pumps were kept running at nominal velocity for the whole transient, as for DEMO requirement. In addition, during dwell, PHTS circuits must be operated at the system average temperature (nearly 310 °C). Since no control strategies related to BZ OTSGs and FW HEXs were available, a preliminary management strategy for the PCS feedwater and IHTS molten salt mass flows were proposed and investigated. The BB PHTS parameters calculated by the code were analyzed to assess the circuit performances. The imposed trends proved to be effective in keeping the PHTS average temperature during dwell at the required value. After, it was performed a benchmark exercise involving DEMO reactor power fluctuations. System code results were compared with the more detailed ones obtained with ANSYS CFX. The aim was to evaluate the effectiveness of the thermal-hydraulic model developed for the blanket component, prepared using equivalent components characterized by lumped parameters. BZ and FW PHTS water temperatures at blanket outlet were selected as figures of merit. Their trends showed a good agreement between the simulation outcomes obtained with the system code and the Finite Element Method (FEM). Results obtained from this benchmark exercise also indicated an effective way to perform simulations involving components, such as the breeding blanket, characterized by complex geometries and heat transfer phenomena. System code and 3D calculations can be externally coupled in an iterative process where CFX provides more accurate parameters to refine the RELAP5 model and the latter is used to update the inlet conditions for finite volume model computation. Finally, the blanket primary cooling system response during accidental conditions was investigated. The selected transients to be studied belong to the category of “Decrease in reactor coolant system flow rate”. This transient analysis was aimed at understanding the thermal-hydraulic response of the blanket component and related primary circuits. In this way, it was possible to evaluate the appropriateness of their pre-conceptual design and the eventual need of mitigation actions to withstand such accidental scenarios. Different faults that could result in a decrease of the BB PHTS primary flow were postulated and investigated. In particular: i) partial and complete loss of forced primary coolant flow; ii) primary pump shaft seizure (or locked rotor); iii) inadvertent operation of a loop isolation valve. Firstly, the most limiting of the above primary flow decrease event was chosen. It consisted in the complete loss of forced circulation in both FW and BZ PHTS. In this ‘worst case’ scenario, even if very unlikely, a sensitivity was performed on the flywheel to be added to the PHTS main coolant pumps in order to keep the system temperatures within acceptable ranges. The proper moment of inertia values to be applied to BZ and FW primary pumps were selected according to the simulation outcomes. Later, they were also used in all the following transient calculations. The initiating events mentioned above were all simulated when interesting either BZ or FW system components (i.e. pumps and loop isolation valves). Calculations were replicated also considering the influence of loss of off-site power, assumed to occur in combination with the PIE. An actuation logic, involving some components of the DEMO reactor, was proposed and preliminary investigated. It was inspired by the one used for Generation III + nuclear power plants. Results highlighted how the type of circulation (natural or forced) characterizing each cooling system is the main element influencing the correspondent thermal-hydraulic performances. If forced circulation is available, the following behavior can be observed in BZ and FW systems.  Few seconds after the start of transient, the temperature spikes at blanket outlet characterizing the trend of both BZ and FW PHTS water are significantly smoothed.  In FW system, the availability of forced circulation in both primary and secondary (only for the first 10 s) circuits limits the pressure increase and avoids the intervention of the pressurizer Pilot-Operated Relief Valve (PORV) in the short term.  The OTSGs cooling capability lasts less. The presence of forced circulation in the primary cooling system enhances the steam generator heat transfer coefficient, increasing the thermal power transferred to the PCS. This reduces the time between two subsequent steam line Safety Relief Valves (SRV) openings and speeds up the evacuation of the water mass present in the OTSGs secondary side. Once terminated, the steam generators are no more able to provide any cooling function to the BZ PHTS.  For more or less two hours from PIE occurrence, the system pressure is controlled by the pressurizer sprays. The first PORV intervention in the long term is significantly delayed.  The temperature slope characterizing both BZ and FW systems (thermally coupled) is higher since pumping power is added to the power balance. This is valid until the pump trip is triggered in each system. Summarizing, forced circulation improves the BZ and FW performances in the short term, smoothing the temperature spikes, but reduces the ones in the mid-long term. In fact, it shortens the cooling interval provided to the BZ PHTS by the steam generators and increases the temperature slope experienced by BZ and FW systems, reducing the reactor grace time. The best management strategy for PHTS pumps is to use, at the start of transient, the forced circulation they provide, in order to avoid excessive temperatures in the blanket, and then stop them, to increase the reactor grace time. In all the transient simulations, BZ and FW systems experienced a positive temperature drift in the mid-long term. It is due to the unbalance between decay heat produced in the blanket and system heat losses, with the former overwhelming the latter. The temperature slope is higher if the forced circulation is still active. In these cases, it must be added another source term to the power balance, represented by the pumping power. In the calculations performed, no Decay Heat Removal (DHR) system was implemented in the input deck and the power surplus is managed by the pressurizer PORV. Power in excess produces a pressure increase and when this parameter reaches the PORV opening setpoint, PHTS water mass is discharged with its associated enthalpy content. This is the way adopted by BZ and FW system to dissipate the power surplus. In the future developments of this research activity, the impact of the DHR system will be also evaluated. In conclusion, simulation outcomes highlighted the appropriateness of the current PHTS design and of the management strategy chosen for the selected accidental scenarios. During the third ITER council (2008), it was established the so-called ITER Test Blanket Module (TBM) program. Its objective is to provide the first experimental data on the performance of the breeding blankets in the integrated fusion nuclear environment. More recently, in 2018, the WCLL option was inserted among the selected blanket concepts to be investigated. From this time, an intense research activity was conducted within the EUROfusion Work Package Plant level system engineering, design integration and physics integration (WPPMI) in order to perform the pre-conceptual and conceptual design phases of ITER WCLL Test Blanket System. The overall work (i.e. TBS) was divided in ‘Part A’, related to TBM set and ‘Part B’, referring to its related ancillary systems. For the latter, R&D effort was led by ENEA and involved many European research institutions and universities, including DIAEE of Sapienza University of Rome. The work was supervised also by Fusion for Energy, the EU organization managing Europe’s contribution to ITER reactor. By the fall of 2020, both design phases were concluded, and the system successfully underwent its Conceptual Design Review. Among the TBM ancillary systems, the most relevant is the Water Cooling System, acting as primary cooling circuit of the TBM module. The design and thermal-hydraulic characterization of this circuit was up to DIAEE. The TBS conceptual design was presented in this document. A special focus was given to the WCS layout whose DIAEE is responsible for (i.e. the candidate took part to). The Water Cooling System was designed to implement the following main functions: i) provide suitable operating parameters to the water flow cooling the TBM in any operational state; ii) transfer thermal power from WCLL-TBM to CCWS; iii) provide confinement for water and radioactive products; iv) ensure the implementation of the WCLL-TBS safety functions. In addition, ITER WCLL-TBM must be DEMO relevant. Such relevancy refers to the water thermodynamic conditions at the TBM (15.5 MPa, 295-328 °C) since the experimental program will deal with the test of this blanket reference concept. The reduced thermal power produced in the TBM set (near 700 kW) with respect to DEMO blanket (1923 MW), allows to use a single water-cooling system for both the FW and the BZ. The correspondent WCS primary flow was computed considering the TBM power balance. The ultimate heat sink for the WCLL-TBM WCS is the ITER Component Cooling Water System (CCWS). With the aim to include an additional barrier between the contaminated primary water and the CCWS coolant, the WCLL-WCS was split in a primary and a secondary loop. In such a way, the CCWS radioactive inventory is kept below the limit in any operative and accidental scenario (note that CCWS is a non-nuclear system). To simplify the WCLL-WCS management, liquid only condition was selected for the secondary coolant instead of the two-phase fluid, as in DEMO PCS. It is worth to emphasize that electricity generation is not a purpose of ITER and, thus, steam production is not required. CCWS provides water coolant at low pressure and temperature (0.8 MPa at 31 °C), and requires that return temperature must be limited to 41 °C. Hence, there is a considerable difference between the average TBM temperature and the average CCWS temperature. To avoid an excessive temperature excursion (i.e. thermal stresses) between the two sides of a single heat exchanger, an economizer was installed in the middle of the WCS primary loop, leading to the typical “eight” shape of this circuit. Therefore, a total of three heat exchangers were considered for the whole WCS, namely: HX-0001 (economizer), HX-0002 (intermediate heat exchanger between primary and secondary loops) and HX-0003 (heat sink delivering power to CCWS). Each heat exchanger was provided with a bypass line allowing the regulation of the exchanged power by tuning the shell side mass flow. Finally, an electrical heater was added to the WCS primary loop in order to compensate the power unbalance in the system. Most of the WCS equipment is installed in the TCWS Vault, at level four of the tokamak building. The rest of the components, including the TBM, is placed in the level one Port Cell #16. Both locations are linked by means of connection pipes hosted in a vertical shaft. To support the WCS design a preliminary transient analysis was performed. For this purpose, a full thermal-hydraulic model of the system was developed by using the DIAEE version of RELAP5/Mod3.3. Since this circuit is directly connected to PbLi loop within the TBM, also these two systems were included in the overall TBS model. A preliminary control system was implemented for both WCS and PbLi loop. All the main circuit parameters (pressure, temperatures, and mass flows) are controlled in order to ensure system stability in any operative scenario and to provide water coolant and breeder at TBM with the required inlet conditions. Firstly, full plasma power state was simulated at both Beginning of Life (BOL) and End of Life (EOL) conditions. Such calculations were needed to test and evaluate the appropriateness of the model prepared. Simulation outcomes demonstrated that control systems corresponding to WCS and PbLi loop are able to ensure the required values at TBM inlet in both the operative scenarios. For WCS, the main differences between BOL and EOL conditions were highlighted, mainly regarding the operation of the temperature control system (i.e., the mass flow through the heat exchangers bypass). WCS and PbLi loop performances in this flat-top states were fully characterized, including the calculation of pressure and temperature fields, as well as the system power balance. In addition, an insight into the TBM behavior during full plasma power condition was given. Its operation does not change from BOL to EOL since it is provided with water coolant and liquid metal at constant thermodynamic conditions and flow rate. It is important to note that a full thermal-hydraulic characterization of the component was out of the scope of the research activity carried out by DIAEE. Nevertheless, TBM box contains part of the WCS circuit and constitutes the system source term. Furthermore, thermal coupling between WCS and PbLi loop occurs inside the module. For this, it was mandatory to properly simulate the heat transfer phenomena taking place within the component. The results obtained with the system code were compared with the more detailed ones available in literature (produced by using FEM methodologies). The latter were used to calibrate the component thermal-hydraulic model. Then, the two steady-state calculations were used as initial condition to simulate operative scenarios and abnormal conditions. The Normal Operation State (NOS) was the first to be analyzed. The WCS and PbLi loop control systems were tested to demonstrate their effectiveness in ensuring stable operations against the pulsed regime characterizing the NOS. Both BOL and EOL conditions were considered in order to assess the change in WCS thermal-hydraulic performances with the system aging. The reference ITER pulsed plasma regime was adopted for simulation purposes. The system code results demonstrated the appropriateness of the WCS and PbLi loop control systems. They are able to ensure water coolant and PbLi at the TBM with nearly constant inlet thermodynamic conditions and flow rate. For water inlet temperature, oscillations were limited to +/- 3 °C, acceptable for WCS and TBM operation. Moreover, it was verified that in any part of the PbLi loop an adequate margin (16 °C) from the freezing point is maintained. Finally, in order to assess and verify the WCS design, two abnormal scenarios were selected and investigated. The aim was to evaluate the system capabilities under degraded conditions and to verify if the standard control strategies without any external action are capable to maintain the TBM cooling function for an entire plasma pulse. This last condition allows to avoid the triggering of the Fast Plasma Shutdown System, demonstrating that a minor accident in the WCS does not interfere with the ITER global operation. The transients considered were: i) LOFA occurring in WCS secondary loop; ii) LOHS, i.e. loss of flow in the CCWS. The worst operative condition was supposed to be the EOL, since plugging and fouling limit the heat exchange. For this, NOS at EOL was imposed as initial condition for the transient calculations. In both scenarios, simulation outcomes highlighted that WCS primary loop is kept in safety conditions over the whole accidental evolution. In addition, the safety margin from the PbLi freezing is ensured by keeping the reference water temperature at the TBM inlet. The current WCS design and the control systems implemented proved to be effective to withstand the selected accidental scenarios.

The discovery of fire is one of the earliest and most significant achievements of man. However, it is a lethal power that has mostly stayed uncontrollable. Big fires occur practically daily and result in significant loss of life and property. The majority of the contents in the houses are flammable. Clothes, blankets, furniture, paper, synthetic polymeric materials, automobile and plane interiors, etc., all burn when the conditions are favorable. The addition of flame retardant to polymeric materials improves their flame retardancy and thermal stability. In this chapter, we will study the addition of micro clay/ nano clay to improve the flame retardancy of polymeric composites to make them feasible to be used in various potential applications.

Multilayer Insulation (MLI) blankets consist of closely spaced aluminum coated shields that are spaced apart to reduce heat transfer between the payload and the environment, particularly in vacuum. In space application, satellite systems and sub-systems are wrapped in MLI blankets to thermally isolate them from the environment and achieve thermal control requirements. During spacecraft launch, the payload undergoes a rapid depressurization before reaching steady state condition. The MLI blankets are usually perforated and/or connected at the boundaries with Velcro strips to allow out-gassing. The blankets can lose their integrity and functionality if the depressurization process is too rapid: the out-gassing flow can tear the perforations, and the pressure differential built-up across the blanket can pull the Velcro strips apart. This paper describes the design and modeling of depressurization through X-slits cut into the blanket and Velcro strips taped along the sides. A methodology is developed, and a model for quantifying the pressure differential build-up is described and applied to a payload enclosure aboard a Delta II rocket.

Abstract Generator noise is one of the primary concerns in generator designs. The most cost-effective way to deal with the noise issue is to incorporate the reduction of sound pressure level in an early design stage. Once a generator is manufactured, it is often expensive to modify the design for reducing noise levels. For old generators with high sound pressure levels, an effective method to lower the generator noise exposure is to employ acoustic blankets wrapped on the generator external surfaces. However, with the application of acoustic blankets, heat transfer through generator walls can be greatly reduced, leading to the higher generator core temperature and higher generator cooling load. This paper has addressed the design of generator acoustic blankets and its impact on generator cooling performance. The analysis has shown that the influence of acoustic blankets on the generator thermal performance is low or moderate. This suggests that the current acoustic blanket design is feasible. Results from this study have been used to optimize the blanket design.

A Starshade is a large deployable structure and sole payload of an external occulter. At 34m in diameter or more, starshades are designed to block most of the light from a nearby star so that a small orbiting space telescope can image and characterize the Earth-like exoplanets in orbit around it. The starshade resembles a sunflower with a circular central disk supporting petals that are arrayed around its periphery. The petal edges are precisely shaped to match an optical profile that prevents diffraction. The area circumscribed by the edges must be completely opaque, black, and non-reflective. The petals and ring structure are covered by specially designed deployable blankets that must remain completely opaque even if they become perforated by micrometeorites. The blankets must also not cause any significant on-orbit thermoelastic loads on the lightweight supporting ring and petal structures despite very large differential thermal strains that are developed between these Kapton blankets and the thermally stable composite ring and petal structures. There are two types of blankets: one for the deployable petals and one for the central support disc that is formed by a lightweight deployable ring truss structure. The starshade blankets cover such a large area that they must be unusually lightweight compared to conventional multi-layer insulated (MLI) spacecraft blankets. The blankets must also stow around the central hub of the spacecraft with the deployable ring and petal structures in a highly repeatable fashion. This makes them ideal candidates for origami folding schemes. Based on prior studies of large deployable rigid arrays, we began with variants on the origami flasher to fold the central ring blanket, which is a minimum of 20m in diameter. We looked at the simplest methods for integrating this large blanket with a mechanical ring truss while providing ample optical baffling and little to no thermally induced loads on the structure. Petal blankets were also developed using deployable softgoods with pseudo-mechanical and shingled designs with optically blocking folds for deployment. The design was developed iteratively utilizing a variety of prototypes to explore and demonstrate the interaction between the softgoods and rigid elements.

It is expected that unmanned on-orbit satellite servicing will soon become state-of-the-art operations. Such tasks will require new robotic tools. In this context, this paper presents the development of a grasping tool for the handling of satellitic thermal blankets. The mechanical design of the tool is first addressed. Mainly, actuated jaws adapted to grasp and lift a thermal blanket attached with velcros are developed. Also, passive compliance is included in order to cope with a position controlled robotic arm and a rigid surface. Then, sensing issues are discussed and included in the design. These features are integrated in a prototype mainly built of plastic by rapid prototyping. Finally, experimental results show that the tool developed in this work is capable of effectively removing thermal blankets.