Dissertations / Theses on the topic 'Heat loads on the divertor'

Cette thèse s’inscrit en support du projet ITER, sur l’étude du comportement thermique de prototypes de CFP dans des tokamaks supraconducteurs : EAST et WEST. Ces prototypes correspondent à un enchaînement de monoblocs de tungstène le long d’un tube de refroidissement, séparés par des interstices (0.5 mm), qui permet d’extraire la chaleur de ces composants. L’introduction de ces interstices entre monoblocs (toroïdaux) ou entre barres de monoblocs (poloïdaux), implique que le bord poloïdal peut être exposé aux lignes de champ avec une incidence quasi-normale. Un échauffement local très important est attendu sur une fine bande latérale de la surface supérieure de chaque monobloc, qui peut être accentué dans le cas où les composants sont désalignés. Nous proposons dans ce travail d’étudier l’impact de deux géométries (arête vive et chanfrein) de ces composants ainsi que de leurs désalignements sur la génération de points chauds locaux, à l’aide de diagnostics embarqués (TC/FBG), et d’une caméra infrarouge très haute résolution (~0.1 mm/pixel), dont l’émissivité varie en fonction de la longueur d’onde, de la température, et de l’état de surface, qui évolue au contact du plasma, lors des différentes campagnes expérimentales. Les sondes de Langmuir permettront de mesurer la température du plasma, et par conséquent d’estimer les rayons de Larmor des ions, qui pourront jouer un rôle important dans la distribution locale du flux de chaleur autour des bords poloïdaux et toroïdaux. Les travaux menés ici, montrent la cohérence entre les calculs prédictifs et les résultats expérimentaux et appuient la décision d'ITER de biseauter les MBs pour protéger leurs bords d'attaque<br>This PhD falls within ITER project support, aiming to study the thermal behavior of ITER-like PFC prototypes in two superconducting tokamaks: EAST (Hefei) and WEST (Cadarache). These prototypes correspond to castellated tungsten monoblocks placed along a cooling tube with small gaps (0.5 mm) between them, called plasma-facing units, to extract the heat from the components. The introduction of gaps between monoblocks (toroidal) and plasma-facing units (poloidal), to relieve the thermomechanical stresses in the divertor, implies that poloidal leading edges may be exposed to near-normal incidence angle. A local overheating is expected in a thin lateral band at the top of each monoblocks, which can be enhanced when the neighboring components are misaligned. In this work, we propose to study the impact of two geometries (sharp and chamfered LEs) of these components, as well as their misalignments on local hot spot generation, by means of embedded diagnostics (TC/FBG), and a submillimeter infrared system (~0.1 mm/pixel), whose emissivity varies with wavelength, and the temperature, but above all, the surface state of the component, which evolves under plasma exposure, during the experimental campaigns. The divertor Langmuir probes measure the plasma temperature, and thus estimate the ion Larmor radius that may play a role in the local heat flux distribution around poloidal and toroidal edges. The results presented in this thesis, confirming the modelling predictions by experimental measurements, support the final decision by ITER to include 0.5 mm toroidal beveling of monoblocks on the vertical divertor targets to protect poloidal leading edges from excessive heat flux

Ice rinks are among the most energy intensive public buildings in developed and developing countries. According to a research on Swedish ice rinks; a typical ice rink consumes approximately 1185 MWh/year which leads to more than 300 GWh/year for the 342 Swedish indoor ice rinks. The refrigeration system is usually the largest consumer by 43% average share of the total energy consumption.  To decrease the refrigeration system energy demand, there are a variety of energy efficiency techniques known and available but the key to select the best ones is finding the major heat loads on the ice sheet and refrigeration system, which is unique for each ice rink. To fulfil this objective and in addition to review literature, this study has two main approaches. The first approach is to measure and evaluate the performance of the refrigeration system in two ice rinks, called Norrtälje and Älta. The estimated cooling capacity is approximately equal to the total heat load on the ice plus the heat gains in the distribution system. This goal has been accomplished by using a performance analyser called “ClimaCheck” which is based on an “internal method” because it uses the compressor as an internal mass flow meter and consequently, there is no need for an external one. The refrigerant mass flow rate is calculated by an energy balance over the compressor. By knowing the mass flow, enthalpy of the refrigerant, etc. the cooling capacity and COP of the system can be calculated. While the total heat load is known by the first approach, the second approach tries to discover different heat loads shares by analytical modelling. The measured physical and thermodynamical parameters plus the ice rink geometrical characteristics are input to the heat transfer correlations to estimate the heat load magnitude. The results of the measurements show that the total energy consumption in Norrtälje is about two third of Älta. The main reasons for this less energy consumption are smarter control systems for compressors and pumps, better ventilation distribution design and 1°C-2°C higher ice temperature.      Analytical modelling for a sample day has estimated that about 84% of the total heat loads is originated from the heat loads on ice sheet while the distribution system causes the remaining 16%. Moreover, calculations show that convection plus small portion of condensation (altogether 36%), radiation (23%), ice resurfacing (14%) and lighting (7%) are the largest heat loads in winter while in summer condensation is another significant heat load (10%). Comparing two six-hour periods, one without ice resurfacing and four resurfacings in the second one, 30% more cooling demand has been calculated for the second period. Furthermore, it has been shown that the evaporator to brine is the contributor for 66% of the heat transfer resistances from ice to evaporator while brine to bottom ice and bottom to top ice accounts for 27% and 7% respectively. To conclude, a parallel “performance analysis of the refrigeration system” and “heat loads estimation” proves to be a useful tool for adopting proper design and control for energy efficient operation.<br>Stoppsladd financed by Swedish Energy Agency (Energimyndigheten) and Swedish Ice Hockey Association

Magnetic confinement fusion has the potential to provide a nearly inexhaustible source of energy. Current fusion energy research projects involve conceptual "Tokamak" reactors, inside of which contaminants are "diverted" along magnetic field lines onto collection surfaces called divertor plates. Approximately 15% of the reactor's thermal power is focused on the divertor plates, creating a need for an effective cooling mechanism. Current extrapolations suggest that divertor plates will need to withstand heat fluxes of more than 10 MW/m2. The cooling mechanism will need to use a coolant compatible with the blanket system; currently helium, and use a minimal fraction of the reactor's available pumping power; ie: will need to experience minimal pressure drops. A leading cooling concept is the Helium Cooled Flat Plate Divertor (HCFP). This thesis experimentally examines four variations of the HCFP. The objectives are to: 1. Experimentally determine the thermal performance of the HCFP with a hexagonal pin-fin array in the gap between the impinging jet and the cooled surface over a range of flow rates and incident heat fluxes; 2. Experimentally measure the pressure drop associated with the hexagonal pin-fin array over a range of flow conditions; 3. Determine and compare the thermal performance of and pressure drop associated with the HCFP for two different slot widths, 0.5 mm and 2 mm over a range of flow rates and incident heat fluxes; 4. Compare the performance of the HCFP with a hexagonal pin-fin array with that of the HCFP with a metal-foam insert and the original HCFP; 5. Provide an experimental data set which can be used to validate numerical models of the HCFP design and its variants. 6. Analytically determine the maximum heat flux which the HCFP can be expected to withstand at theoretical operating conditions in the original and pin-fin array configurations.

Thesis (Ph.D.)--Mechanical Engineering, Georgia Institute of Technology, 2008.<br>Committee Co-Chair: Minami Yoda, Co-Advisor; Committee Co-Chair: Said I. Abdel-Khalik; Committee Member: Donald R. Webster; Committee Member: Narayanan M. Komerath; Committee Member: S. Mostafa Ghiaasiaan; Committee Member: Yogendra Joshi

Exhausting the thermal power from a fusion tokamak is a critical engineering challenge. The life of components designed for these conditions has a strong influence on the availability of the machine. For a fusion power plant this dependence becomes increasingly important, as it will influence the cost of electricity. The most extreme thermal loading for a fusion power plant will occur in the divertor region, where components will be expected to survive heat fluxes in excess of 10 MW/m² over a number of years. This research focussed on the development of a heat sink module for operation under such conditions, drawing on advanced cooling strategies from the aerospace industry. A reference concept was developed using conjugate Computational Fluid Dynamics. The results were experimentally validated by matching Reynolds numbers on a scaled model. Heat transfer data was captured using a transient thermochromic liquid crystal technique. The results showed excellent agreement with the corresponding numerical simulations. To facilitate comparison against other divertor heat sink proposals, a nondimensional figure of merit for cooling performance was developed. When plotted against a non-dimensional mass flow rate, the reference heat sink was shown to have superior cooling performance to all other divertor proposals to date. Results from Finite Element Analysis were used in conjunction with the ITER structural design criteria to life the heat sink. The sensitivity of life to both boundary conditions, and local geometric features, were explored. The reference design was shown to be capable of exceeding the life requirements for heat fluxes in excess of 15 MW/m². A number of heat sinks, based on the reference design, were fabricated. These underwent non-destructive testing, before experimentation in a high-heat flux facility developed by the author. The heat transfer performance of the tested modules was found to exceed that predicted by numerical modelling, which was concluded to be caused by the fabrication processes used.

Thesis (M. S.)--Nuclear Engineering, Georgia Institute of Technology, 2009.<br>Committee Chair: Abdel-Khalik, Said; Committee Co-Chair: Yoda, Minami; Committee Member: Ghiaasiaan, S. Mostafa. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Computational Fluid Dynamics (CFD) simulations are presented within this study for super-cooled liquid oxygen atomisation and gasification in a subcritical chamber operating at 1MPa. Relatively low cost simulation techniques have been used and their accuracy evaluated. Gasification efficiency expected from theory is compared with simulation results and physical limitation in addition to modelling limitations are discussed. Impinging jets have been used within the simulations with the intent of atomising the incoming liquid oxygen, followed by injection of hot water vapour perpendicularly, to increase turbulent mixing, residence time and in turn expected gasification efficiency. A computational fluid dynamics heating analysis is also included in order to highlight constraints on the chamber geometry imposed by transient rapid oxidation material limits. 316 stainless steel and 3D printed Inconel 718 were investigated experimentally to identify their transient macroscopic rapid oxidation limits. This information supplements existing published literature for operation at high temperatures for a transient period of time in oxygen rich environments. ANSYS Fluent 2020R1, and its newly included Volume of Fluid to Discrete Particle (VOF-DPM) Model, is used for CFD simulation of LOx atomisation and vaporisation. The CFD simulation technique is discussed in detail in order to allow the reader to gain knowledge into areas where computational power can be saved while still allowing assessment of trends for conducting relatively quick feasibility reviews e.g. for different chamber configurations. The CFD simulation results are compared with published experimental data and its accuracy when extended to this application is discussed. Results indicate that gasification of LOx within a compact chamber may be feasible if sufficient turbulence, resulting in longer residence times is present providing sufficient time for heat and mass transfer from the continuous phase. Simulations indicate that due to the mixing and gasification process the LOx particles within the chamber that have not entered the gaseous phase are smaller than that from pure atomisation and therefore more susceptible to gasification if injected into the main motor combustion chamber. Results hint at the potential benefit of swirl injection of hot gases to increase residence time and in turn the gasification efficiency, therefore, this is recommended for the topic of future research.<br>Computational Fluid Dynamics (CFD) simuleringar presenteras i denna studie för superkyld flytande syreförstoftning och förgasning i en underkritisk kammare som arbetar vid SI 1 MPa. Relativt billiga simuleringstekniker har använts och deras noggrannhet utvärderats. Förgasningseffektivitet som förväntas från teorin jämförs med simuleringsresultat och fysisk begränsning utöver detta diskuteras modelleringsberäkningarna. Stötstrålar har använts inom simuleringarna med avsikt att finfördela det inkommande flytande syret, följt av injektion av varm vattenånga vinkelrätt, för att öka turbulent blandning, uppehållstid och i sin tur förväntad förgasningseffektivitet. En beräkningsenhetsanalys för uppvärmningsdynamik ingår också för att belysa begränsningar för kammargeometri som införs genom övergående gränser för snabb oxidation. 316 rostfritt stål och 3D-printad Inconel 718 undersöktes experimentellt för att identifiera deras övergående makroskopiska snabba oxidationsgränser. Denna information kompletterar befintlig publicerad litteratur för drift vid höga temperaturer under en kort tid i syrgasrika miljöer. ANSYS Fluent 2020R1, och dess nyligen inkluderade volym av vätska till diskret partikel (VOF-DPM) -modell, används för CFD-simulering av LOxatomisering och förångning. CFD-simuleringstekniken diskuteras i detalj för att göra det möjligt för läsaren att få kunskap om områden där beräkningskraft kan sparas medan man fortfarande tillåter bedömning av trender för att göra relativt snabba genomförbarhetsgranskningar, t.ex. för olika kammarkonfigurationer. CFD-simuleringsresultaten jämförs med publicerade experimentella data och dess noggrannhet när den utvidgas till denna applikation diskuteras. Resultaten indikerar att förgasning av LOx i en kompakt kammare kan vara möjlig vid tillräcklig turbulens, vilket resulterar i längre uppehållstider är närvarande som ger tillräcklig tid för värme och massöverföring från den kontinuerliga fasen. Simuleringar indikerar att på grund av blandnings- och förgasningsprocessen är LOx-partiklarna i kammaren som inte har gått in i gasfasen mindre än den från ren förgasning och därför mer mottagliga för förgasning om de injiceras i huvudmotorns förbränningskammare. Resultat antyder den potentiella fördelen med virvelinjektion av heta gaser för att öka uppehållstiden och i sin tur förgasningseffektivitet, därför rekommenderas detta för ämnet för framtida forskning.

Smart controls for heat pumps are required to harness the full energy flexibility potential of building thermal loads. A literature review revealed that most strategies used for this purpose can be classified in two categories: simpler rule-based control (RBC), and model predictive control (MPC), a more complex strategy based on optimization and requiring a prior model of the systems. Both RBC and MPC can use external penalty signals to prompt their actions. The price of electricity is most often used for this purpose, leading to strategies of cost reduction. As an alternative penalty signal, a novel marginal CO2 emissions signals was also conceived. In this thesis, both an RBC and an MPC controllers were developed as supervisory controls for an air-to-water heat pump supplying the heating and cooling needs of a residential building type from the Mediterranean area of Spain. The RBC strategy modulates the temperature set-points, while the MPC strategy minimizes the overall summed penalties (costs or emissions) due to the heat pump use, while balancing with comfort constraints and a proper operation of the systems. The MPC controller in particular required the development of a simplified model of the building envelope and of the heat pump performance, both adjusted differently for heating or cooling. The MPC included several novelties, such as the mixed-integer formulation, the heat pump simplified model based on experimental data and the consideration of its computational delay. The developed controllers were then tested, firstly in an experimental “hardware-in-the-loop” setup, with a real heat pump installed in the laboratory facilities, and connected to thermal benches that emulated the loads from a building model. Implementing the control strategies on a real heat pump enabled to highlight some practical challenges such as model mismatch in the MPC, communication issues, interfacing and control conflicts with the heat pump local controller. Secondly, a simulation-only framework was developed to test other configurations of the controllers, with TRNSYS as the main dynamic building simulation tool, coupled with MATLAB for the MPC controller. In that case, the real heat pump was replaced by a detailed model which was specially developed for this purpose. It is based on static tests performed in the laboratory, and therefore reproduces the dynamic behavior of the heat pump with high fidelity. The results from experimental and simulation studies revealed the ability of both types of controllers to shift the building loads towards periods of cheaper or less CO2-emitting electricity, these two objectives being in fact contradictory. In the cases where the reference control presented a large margin for improvements, the RBC and MPC controllers performed equally and provided important savings: around 15% emissions savings in heating mode, and 30% cost savings in cooling mode. In the cases where the reference control already performed close to optimally, the RBC controller failed to provide improvements, while the MPC benefitted from its stronger optimization and prediction features, reaching 5% cost savings in heating mode and 10% emissions savings in cooling mode. The research carried out in this thesis covered many aspects of energy flexibility in buildings: creation of input penalty signals, graphical representation of flexibility, development of controllers, performance in realistic experimental setup, fitting of appropriate models and compared performance in heating and cooling. The development efforts and barriers hindering the deployment of MPC controllers at large scale for building climate control have additionally been discussed. The performance of the developed controllers was evidenced in the thesis, proving their potential for load-shifting incentivized by different penalty signals: they could become a strong asset to unlock demand-side flexibility and in fine, help integrating a larger share of RES in the grid.<br>Para aprovechar todo el potencial de flexibilidad energética de las cargas térmicas en los edificios equipados con bombas de calor se requiere de sistemas de control inteligente. Una revisión bibliográfica ha revelado que la mayoría de las estrategias de gestión utilizadas para esta finalidad pueden ser clasificadas en dos categorías: control en base a reglas (RBC en inglés) o predictivo (MPC en inglés), basado en optimización y en el uso de modelos. Tanto RBC como MPC pueden utilizar señales externas de penalización para fundamentar sus decisiones. El precio de la electricidad es utilizado a este fin de forma habitual en estrategias de reducción de coste. Una nueva señal de emisiones marginales de CO2 fue también creada como alternativa. Se han desarrollado un controlador RBC y un MPC para sistemas de bombas de calor aire-agua que cubren las demandas de climatización y agua caliente en el ámbito residencial. El RBC modula las consignas de temperatura, y el MPC minimiza las penalizaciones totales del sistema, al mismo tiempo que se consideran restricciones operativas y de confort. En particular, el MPC ha requerido el desarrollo de nuevos modelos simplificados, para predecir la demanda del edificio y el rendimiento de la bomba de calor, tanto en modo calefacción como en modo refrigeración. Otras novedades añadidas en la configuración del MPC son la formulación entera mixta, y la consideración del retraso debido al tiempo de cómputo. Los controladores fueron testeados, primeramente, en un entorno experimental -hardware-in-the-loop-, con una bomba de calor real instalada en el laboratorio y conectada a unos bancos térmicos que emulan las cargas térmicas del edificio. El entorno experimental ha permitido poner de manifiesto algunos retos prácticos tales como la discrepancia en el modelo del MPC y conflictos de conexión con el controlador local de la bomba de calor. En segundo lugar, un entorno de simulación ha sido creado para testear diversas configuraciones, usando TRNSYS acoplado con MATLAB. Para ello, se ha desarrollado un modelo detallado de la bomba de calor, basado en ensayos realizados en laboratorio, que reproduce el comportamiento dinámico de la bomba de calor con alta fidelidad. Tanto los resultados experimentales como los simulados han revelado la capacidad de los dos tipos de control de desplazar las cargas del edificio hacia periodos donde la electricidad era más barata o había menos emisiones de CO2, estos dos objetivos presentando de hecho impactos contradictorios. En los casos donde el control de referencia presentaba un amplio margen de mejora, los controladores RBC y MPC han demostrado la capacidad de actuar eficientemente y proveer ahorros importantes: alrededor de un 15% de emisiones en modo calefacción, y de un 30% de coste en modo frío. En aquellos casos en el que el control de referencia actuaba de forma cercana a la óptima, los controladores RBC no han sido capaces de aportar mejoras significativas, mientras que el MPC ha demostrado la capacidad de conseguir ahorros de un 5% de coste en modo calefacción y de un 10% de emisiones en modo frío. La investigación realizada en esta tesis ha abarcado amplios aspectos de la flexibilidad energética en los edificios: la generación de señales de penalización, la representación gráfica del potencial de flexibilidad, el ajuste de modelos simplificados, el desarrollo de controladores, el ensayo en entorno experimental y de simulación, con la consecuente evaluación de su rendimiento comparado en periodos de invierno y de verano, así como una discusión de las barreras que dificultan la implementación de controladores MPC y RBC a gran escala. Finalmente, la tesis ha evidenciado el rendimiento de los controladores desarrollados si se formulan de forma adecuada, demostrando su potencial para el desplazamiento del consumo eléctrico en la edificación residencial con sistemas de bomba de calor respondiendo a diferentes señales de penalización. En conclusión, los sistemas propuestos pueden ser elementos muy valiosos para favorecer la necesaria flexibilidad de la demanda térmica en la edificación y posibilitar la integración de sistemas de generación renovables en la red

In this thesis, the numerical and experimental investigation of a passive cooling scheme using a thermal radiation shield for a storage building is presented. The thermal radiation shield is found to be effective in improving the thermal performance of the enclosure in terms of reducing temperatures of the interior air as well as the surfaces of the enclosure, and more efficient with higher heat load and without ventilation.

Une compréhension profonde du transport du plasma au bord d'un réacteur à fusion par confinement magnétique est obligatoire pour gérer l'extraction de puissance. Dans les dispositifs de fusion de nouvelle génération, des limites technologiques contraignent le flux de chaleur maximal au divertor. Pour une puissance d'échappement donnée le flux de chaleur maximal est déterminé par l'amplitude de l'empreinte du plasma au mur. Les profils de flux de chaleur au divertor peuvent être paramétrés par deux échelles de longueur du transport. Nous remettons en question l'interprétation actuelle de ces deux échelles de longueur en étudiant l'impact de la géométrie du divertor sur l'échappement. En particulier, un élargissement des profils de flux de chaleur avec la longueur de la jambe du divertor externe est diagnostiqué. Des efforts de modélisation ont montré que les simulations diffusives reproduisent les profils expérimentaux de flux de chaleur pour les plasmas à jambes courtes. Inversement, l'étalement du flux de chaleur pour une longe jambe du divertor est reproduit par un modèle turbulent, soulignant l'importance de la turbulence aussi dans le divertor. Ces résultats remettent en question l'interprétation de la largeur du flux de chaleur comme grandeur liée a la main SOL uniquement. Les configurations magnétiques avec une longe jambe du divertor mettent en évidence l'importance du transport asymétrique dans le divertor. Nous concluons que le transport dans la main SOL et celui dans le divertor ne sont pas à découpler et nous soulignons l'importance de la géométrie magnétique sur le transport turbulent avec l'avantage potentiel d'un inattendu étalement du dépôt de puissance<br>A deep understanding of plasma transport at the edge of a magnetically confined fusion device is mandatory for a sustainable and controlled handling of the power exhaust. In the next-generation fusion device ITER, technological limits constrain the peak heat flux on the divertor. For a given exhaust power the peak heat flux is determined by the extent of the plasma footprint on the wall. Heat flux profiles at the divertor targets of X-point configurations can be parametrized by using two length scales for the transport of heat in SOL. In this work, we challenge the current interpretation of these two length scales by studying the impact of divertor geometry modifications on the heat exhaust. In particular, a significant broadening of the heat flux profiles at the outer divertor target is diagnosed while increasing the length of the outer divertor leg. Modelling efforts showed that diffusive simulations well reproduce the experimental heat flux profiles for short-legged plasmas. Conversely, the broadening of the heat flux for a long divertor leg is reproduced by a turbulent model, highlighting the importance of turbulent transport not only in the main SOL but also in the divertor. These results question the current interpretation of the heat flux width as a purely main SOL transport length scale. In fact, long divertor leg magnetic configurations highlighted the importance of asymmetric divertor transport. We therefore conclude that main SOL and divertor SOL transport cannot be arbitrarily disentangled and we underline the importance of the divertor magnetic geometry in enhancing asymmetric turbulent transport with the potential benefit of an unexpected power spreading

Degut a la fi de l’escalament de Dennard, la potència i la densitat de potència requerides pel funcionament dels xips comencen a augmentar. Si aquesta tendència continués en augment, el consum d’energia seria prohibitiu tant per criteris d’eficiència com per a la gestió tèrmica. Per tal de complir els criteris d’eficiència i gestió tèrmica, la millora dels xips es va limitar restringint el nombre de nuclis i la seva freqüència de funcionament. Aquesta tendència implica la necessitat d’una solució de refrigeració capaç d’extreure un flux de calor heterogeni d’alta densitat de potència i variant en el temps, a més de reduir el gradient de temperatura que redueix la fiabilitat de l’electrònica. Aquesta tesi es desenvolupa en el marc del projecte Europeu Horitzó 2020 STREAMS (Smart Technologies for eneRgy Efficient Active cooling in advanced Microelectronics Systems), que té com a objectiu desenvolupar un dispositiu capaç de satisfer les necessitats de refrigeració de la microelectrònica. L’objectiu principal d’aquesta tesi és desenvolupar un sistema de refrigeració de cel·les microfluídiques i avaluar el seu impacte en la microelectrònica i en els receptors fotovoltaics de concentració. El dispositiu de refrigeració desenvolupat està format per una matriu de cel·les microfluídiques, cadascuna de les quals és responsable de l’extracció del flux de calor local. El refrigerant es subministra a les cel·les de forma paral·lela mitjançant canals de subministrament i de recollida connectats als col·lectors. Per tant, cada cel·la té l’entrada de refrigerant fred independentment de la seva localització. La calor és extreta per cada cel·la, la qual pot contenir microcanals que milloren la transferència de calor i vàlvules autoadaptatives capaces d’ajustar el cabal a les seves necessitats de refrigeració. En l’etapa de disseny, la cel·la microfluidica MC6T és dissenyada i avaluada numèricament en un escenari de càrrega de calor no uniforme i variable en el temps, reduint el cabal en un 42.5 % i la caiguda de pressió en un 81.0 % comparat amb un dispositiu de microcanals sotmès a les mateixes condicions. La combinació de la reducció de cabal i la caiguda de pressió suposa una disminució de la potència mitjana de bombeig en un 89.1 % comparat amb un dispositiu de microcanals. Tanmateix també es millora la uniformitat de temperatura gràcies a l’ús de les vàlvules microfluídiques. Altrament, s’avalua numèricament l’impacte d’aquest nou dispositiu de refrigeració sobre els receptors fotovoltaics de concentració solar (CPV) de matriu densa. Segons la configuració elèctrica dels receptors i de la no uniformitat del perfil d’irradiació, l’increment de potència pot arribar a un 9.7 % comparat amb el mateix receptor CPV refrigerat amb microcanals. Un cop validat numèricament el concepte i després de la identificació i resolució dels reptes inherents al procediment de microfabricació dels dispositius autoadaptatius de refrigeració, es fabriquen els dispositius dissenyats per tal d’avaluar experimentalment el rendiment del sistema de cel·les microfluídiques, amb vàlvules autoadaptatives i sense. A més a més, s’aplica un algoritme de control que adapta el cabal total del dispositiu a les necessitats d’extracció d’aquest. Si es compara el nou disseny amb un dispositiu de microcanals convencionals amb cabal constant, la matriu de cel·les microfluidiques sense vàlvules redueix la potència de bombeig en un 83.7 % i presenta una millora del 10.8 % en uniformitat de temperatura. Tot i això, la matriu de cel·les amb vàlvules autoadaptatives redueix la potència de bombeig en un 74.7 %, al mateix temps que també millora la uniformitat de temperatura en un 31.7 %. Altrament, quan s’aplica l’algoritme de control de cabal al dispositiu de microcanals, la potència de bombeig requerida pels dispositius de cel·les microfluídiques amb vàlvules autoadaptatives i sense és, respectivament, del 15.5 % i del 45.6 % en comparació amb microcanals. En aquestes condicions, la uniformitat de temperatura de les cel·les microfluídiques sense vàlvula és semblant a la dels microcanals amb cabal controlat, però el dispositiu de cel·les amb vàlvules millora la uniformitat de temperatura en un 23.9 %.<br>Con el fin del escalamiento de Dennard, la potencia y la densidad de potencia requeridas por chip empiezan a aumentar. Si esta tendencia continuara, el consumo de energía sería prohibitivo tanto por criterios de eficiencia como para la gestión térmica. Para cumplir los criterios de eficiencia y gestión térmica la mejora de los chips se limitó restringiendo el número de núcleos y su frecuencia de funcionamiento. Esta tendencia implica la necesidad de una solución de refrigeración capaz de extraer un flujo de calor heterogéneo de alta densidad de potencia y variando en el tiempo, además de reducir el gradiente de temperatura que reduce la fiabilidad de la electrónica. Esta tesis se desarrolla en el marco del proyecto europeo Horizonte 2020 STREAMS (Smart Technologies for eneRgy Efficient Active cooling in advanced Microelectronics Systems), que tiene como objetivo desarrollar un dispositivo de refrigeración capaz de satisfacer las necesidades de refrigeración en la microelectrónica. El objetivo principal de esta tesis es desarrollar un sistema de refrigeración de celdas microfluídicas y evaluar su impacto en microelectrónica y en receptores fotovoltaicos de concentración. El dispositivo de refrigeración está formado por una matriz de celdas microfluídicas, cada una de las cuales es responsable de la extracción del flujo de calor local. El refrigerante se suministra a las celdas paralelamente mediante canales de suministro y recogida conectados a los colectores. Por lo tanto, cada celda tiene la entrada de refrigerante frío independientemente de su localización. El calor es extraído por cada celda la cual puede contener microcanales para mejorar la transferencia de calor y válvulas autoadaptativas capaces de adaptar el caudal de cada celda a sus necesidades de refrigeración. En la etapa de diseño, la celda microfluídica MC6T es diseñada y evaluada numéricamente en un escenario de carga de calor no uniforme y variable en el tiempo, reduciendo el caudal un 42.5 % y la caída de presión un 81.0 % comparado con un dispositivo de microcanales sometido a las mismas condiciones. La combinación de la reducción de caudal y caída de presión supone una reducción de la media de potencia de bombeo de un 89.1 % en comparación con microcanales, mientras se mejora la uniformidad de temperatura gracias al uso de las válvulas microfluídicas. En otro caso, se evalúa numéricamente el impacto de este nuevo dispositivo de refrigeración sobre los receptores fotovoltaicos de concentración solar (CPV) en matriz densa. Según la configuración eléctrica de los receptores y de la no uniformidad del perfil de irradiación, el incremento de potencia puede llegar a un 9.7 %, comparado con el mismo receptor CPV refrigerado con microcanales. Una vez validado numéricamente el concepto y tras la identificación y resolución de retos inherentes al procedimiento de microfabricación de los dispositivos autoadaptativos de refrigeración, se fabrican los dispositivos diseñados para evaluar experimentalmente el rendimiento del sistema de celdas microfluídicas, con y sin válvulas autoadaptativas. Además, se aplica un algoritmo de control que adapta el caudal total del dispositivo a las necesidades de extracción del dispositivo. Comparando con microcanales convencionales con caudal constante, la matriz de celdas microfluídicas sin válvulas reduce la potencia de bombeo en un 83.7 % y presenta una mejora del 10.8 % en uniformidad de temperatura. Sin embargo, la matriz de celdas con válvulas autoadaptativas reducen la potencia de bombeo en un 74.7 %, al tiempo que también mejora la uniformidad de temperatura en un 31.7 %. De lo contrario, cuando se aplica el algoritmo de control de caudal también al dispositivo de microcanalas, la potencia de bombeo requerida por los dispositivos de celdas microfluídicas con y sin válvulas autoadaptativas es, respectivamente, el 15.5 % y el 45.6 % comparado con microcanales. En estas condiciones, la uniformidad de temperatura de las celdas microfluídicas sin válvula es similar a la de los microcanales con caudal controlado, pero el dispositivo de celdas con válvulas mejora la uniformidad de temperatura en un 23.9%.<br>With the end of Dennard scaling, the power and the power density required by chips start to increase. If this trend were to continue, the microelectronics power consumption needed to satisfy efficiency requirements and for thermal management would be prohibitive. To meet the efficiency and thermal management requirements, the chip improvement is limited by restricting the number of cores and their operation frequency. This trend implies the need for a cooling solution that is able to extract the non-uniform and time-dependent high power density heat flux and reduce the temperature non-uniformity, which reduces the electronic reliability. This thesis is developed in the framework of the Horizon 2020 Project STREAMS (Smart Technologies for eneRgy Efficient Active cooling in advanced Microelectronics Systems), which aims to develop a cooling device that is able to satisfy the microelectronics cooling needs. The main objective of this thesis is to design a microfluidic cell cooling system and assess its impact on the microelectronics and concentrating photovoltaic receivers. The cooling device is formed by an array of microfluidic cells, each one responsible for removing the local heat flux. Coolant flow is fed in parallel to the cells by interdigitated cold and warm flow channels connected to manifolds. Each cell therefore has a cold inlet flow, irrespective of its location. Heat is removed by the flow through each cell, which can contain microchannels to enhance the heat transfer and self-adaptive valves capable of tailoring the flow rate of each cell to its cooling needs. In the design stage, the MC6T microfluidic cell is designed and numerically assessed under a non-uniform and time-dependent heat load scenario, reducing the flow rate by 42.5 % and the pressure drop by 81.0 % with respect to the microchannel cooling device under the same boundary conditions. The combination of both low flow rates and pressure drops implies an average pumping power reduction of 89.1 % in comparison to microchannels, while the temperature uniformity is improved by the use of the self-adaptive microfluidic valves. The impact of this novel cooling solution on the performance of dense array CPV receivers is numerically assessed. Depending on the electrical configuration and the non-uniformity of the illumination profile, the increase in power generation of the dense array CPV receiver can reach up to 9.7 %, compared with the same CPV receiver cooled by microchannels. Once the concept is validated numerically, and after identifying and resolving the challenges inherent in the microfabrication procedure of self-adaptive cooling devices, selected designs are fabricated in order to assess experimentally the performance of the self-adaptive microfluidic cell cooling device, with and without self-adaptive valves. A control algorithm tailors the total flow rate to the heat extraction needs. Compared to conventional microchannels with fixed flow rates, the microfluidic cell array without valves improves the pumping power by 83.7 % and improves a 10.8 % in terms of temperature uniformity. However, the array of microfluidic cells with self-adaptive valves reduces the pumping power by 74.7 %, while the temperature non-uniformity is reduced by 31.7 %. When applying the flow rate control algorithm to the microchannels, the pumping power needs of the array of microfluidic cells with and without self-adaptive valves are, respectively, 15.5 % and 45.6 %, compared to microchannels. In these conditions, the temperature uniformity of the microfluidic cell without self-adaptive valves presents a similar behaviour as the flow rate controlled microchannels, however the microfluidic cell with self-adaptive valves improves the temperature uniformity a 23.9 %.

<p> The increasing power density of high-performance electronics has created a need for advanced thermal management strategies. Vapor compression cycles (VCC) offer large heat transfer coefficients via low coolant temperatures and boiling heat transfer, and thus are attractive for electronics cooling. However, the high heat flux imposed by electronics requires new modeling and control techniques for VCC implementation. Challenges include transient heat loads, critical heat flux (CHF), refrigerant charge management, and multi-evaporator management. This dissertation presents research to improve the fundamental understanding of systems-level design, modeling and control of multiple evaporator VCC for high heat flux removal. An experimental testbed is presented, with the option of switching between a heated accumulator and a recuperator to maintain cycle active charge. Static component, heat transfer, and dryout models are identified, and low-order lumped dynamic system models are developed and validated for both accumulator and recuperator operation. The static and dynamic models are used to develop robust, decoupled dryout avoidance controls to provide stability, reject large thermal disturbances and improve cycle energy efficiency. Finally, experimental and simulation results are presented for control validation.</p>

Une compréhension profonde du transport du plasma au bord d'un réacteur à fusion par confinement magnétique est obligatoire pour gérer l'extraction de puissance. Dans les dispositifs de fusion de nouvelle génération, des limites technologiques contraignent le flux de chaleur maximal au divertor. Pour une puissance d'échappement donnée le flux de chaleur maximal est déterminé par l'amplitude de l'empreinte du plasma au mur. Les profils de flux de chaleur au divertor peuvent être paramétrés par deux échelles de longueur du transport. Nous remettons en question l'interprétation actuelle de ces deux échelles de longueur en étudiant l'impact de la géométrie du divertor sur l'échappement. En particulier, un élargissement des profils de flux de chaleur avec la longueur de la jambe du divertor externe est diagnostiqué. Des efforts de modélisation ont montré que les simulations diffusives reproduisent les profils expérimentaux de flux de chaleur pour les plasmas à jambes courtes. Inversement, l'étalement du flux de chaleur pour une longe jambe du divertor est reproduit par un modèle turbulent, soulignant l'importance de la turbulence aussi dans le divertor. Ces résultats remettent en question l'interprétation de la largeur du flux de chaleur comme grandeur liée a la main SOL uniquement. Les configurations magnétiques avec une longe jambe du divertor mettent en évidence l'importance du transport asymétrique dans le divertor. Nous concluons que le transport dans la main SOL et celui dans le divertor ne sont pas à découpler et nous soulignons l'importance de la géométrie magnétique sur le transport turbulent avec l'avantage potentiel d'un inattendu étalement du dépôt de puissance<br>A deep understanding of plasma transport at the edge of a magnetically confined fusion device is mandatory for a sustainable and controlled handling of the power exhaust. In the next-generation fusion device ITER, technological limits constrain the peak heat flux on the divertor. For a given exhaust power the peak heat flux is determined by the extent of the plasma footprint on the wall. Heat flux profiles at the divertor targets of X-point configurations can be parametrized by using two length scales for the transport of heat in SOL. In this work, we challenge the current interpretation of these two length scales by studying the impact of divertor geometry modifications on the heat exhaust. In particular, a significant broadening of the heat flux profiles at the outer divertor target is diagnosed while increasing the length of the outer divertor leg. Modelling efforts showed that diffusive simulations well reproduce the experimental heat flux profiles for short-legged plasmas. Conversely, the broadening of the heat flux for a long divertor leg is reproduced by a turbulent model, highlighting the importance of turbulent transport not only in the main SOL but also in the divertor. These results question the current interpretation of the heat flux width as a purely main SOL transport length scale. In fact, long divertor leg magnetic configurations highlighted the importance of asymmetric divertor transport. We therefore conclude that main SOL and divertor SOL transport cannot be arbitrarily disentangled and we underline the importance of the divertor magnetic geometry in enhancing asymmetric turbulent transport with the potential benefit of an unexpected power spreading

The behavior of aluminum alloy ship deck panels under the thermal loads of Vertical Take-off-and Landing (VTOL) capable aircraft has become a question of interest with the introduction of new primarily aluminum alloy ships to the U.S. Naval Fleet. This study seeks to provide an initial investigation of this question by examining the transient transfer of heat through aluminum alloy ship deck panels under application of the local heat transfer similar to that of a VTOL aircraft exhaust plume core in typical operation. In this study, a jet stream intended to replicate the key physics of the core of a VTOL aircraft plume was impinged onto the upper surface of aluminum alloy corrugated deck panel test specimen. Temperature measurements are taken via thermocouples on the face of the specimen opposite the impingement to evaluate heat transfer through the specimen. This data is used to assess the effects of variation in the geometry of the corrugation between specimen. Qualitative temperature distributions were also gathered on the impingement surface via thermal imaging. A quantitative assessment of the heat paths for transverse and vertical heat transfer was made based on a thermal resistance model, leading to a conceptual description of predominant heat flow paths in the specimen, specifically weld lines between the corrugation and the flat plate surfaces. In support of this, thermal images indicated that the weld lines provided paths for heat to be pulled away from the center of heat application more rapidly than over the rest of the surface. Ultimately, heat transfer through the specimen was found to be more dependent on the flow conditions than the variations in geometry of the deck panels due to the low variation in thermal resistance across the plate. A recommendation is made based upon this observation to use the deck panels similarly to heat exchanges by adding a small amount of through-deck airflow in the areas of high heat load.<br>Master of Science

Questo progetto è incentrato sulla modellizzazione del plasma di bordo dei reattori a fusione nucleare attualmente più conosciuti e diffusi al mondo, i tokamak. Nel divertore, la regione dedicata all'interazione plasma-parete, le condizioni devono garantire le transizioni da un regime caratterizzato da un plasma ionizzante e quindi con una popolazione di atomi neutri molto piccola, ad uno stato con un forte accoppiamento tra i neutri e il plasma, separati da un fronte di ionizzazione, per ottenere infine uno stato di plasma ricombinante dominato dagli atomi neutri. In questo quadro quindi, si è studiato approfonditamente il modello a due punti, un modello teorico ampiamente utilizzato nell'ambito della fisica dei plasmi di bordo. Questo modello trova un'applicazione pratica nello sviluppo di un codice a basso sforzo computazionale per la descrizione del plasma di bordo chiamato SOLDIV, che è stato sviluppato all'IRFM, istituto di ricerca sede del periodo di tirocinio. Parte del lavoro di tesi è consistito nel miglioramento del modulo per la descrizione del divertore, attraverso l'implementazione di elementi fisici aggiuntivi come il grado di detachment, con il vincolo del mantenimento di un basso tempo di calcolo. La particolare geometria del tokamak induce l'insorgere di forti flussi di calore nella zona di bordo, anche detta scrape-off layer. Questo fenomeno può avere conseguenze macroscopiche e incidere sull'efficienza della macchina se non venisse controllato, ed è stato infine oggetto di studio nel presente elaborato. L'obiettivo dell'analisi è stato quello di determinare la posizione del fronte di ionizazzione e di trovare un modello semplice 1D per poterne prevedere la locazione e il comportamento degli aspetti fisici che dominano la regione del divertore quali il fenomeno della biforcazione.

Stand-alone hybrid energy systems are an attractive option for remote communities without a connection to a main power grid. However, the intermittent nature of solar and other renewable sources adversely affects the reliability with which these systems respond to load demands. Hybridisation, achieved by combining renewables with combustion-based supplementary prime movers, improves the ability to meet electric load requirements. In addition, the waste heat generated from backup Internal Combustion Engines or Micro Gas Turbines can be used to satisfy local heating and cooling loads. As a result, there is an expectation that the overall efficiency and Greenhouse Gas Emissions of stand-alone systems can be significantly improved through waste heat recovery. The aims of this PhD project are to identify how incremental increases to the hardware complexity of hybridised stand-alone energy systems affect their cost, efficiency, and CO2 footprint. The research analyses a range of systems, from those designed to meet only power requirements to others satisfying power and heating (Combined Heat and Power), or power plus both heating and cooling (Combined Cooling, Heating, and Power). The majority of methods used focus on MATLAB-based Genetic Algorithms (GAs). The modelling deployed finds the optimal selection of hardware configurations which satisfy single- or multi-objective functions (i.e. Cost of Energy, energy efficiency, and exergy efficiency). This is done in the context of highly dynamic meteorological (e.g. solar irradiation) and load data (i.e. electric, heating, and cooling). Results indicate that the type of supplementary prime movers (ICEs or MGT) and their minimum starting thresholds have insignificant effects on COE but have some effects on Renewable Penetration (RP), Life Cycle Emissions (LCE), CO2 emissions, and waste heat generation when the system is sized meeting electric load only. However, the transient start-up time of supplementary prime movers and temporal resolution have no significant effects on sizing optimisation. The type of Power Management Strategies (Following Electric Load-FEL, and Following Electric and Following Thermal Load- FEL/FTL) affect overall Combined Heating and Power (CHP) efficiency and meeting thermal demand through recovered heat for a system meeting electric and heating load with response to a specific load meeting reliability (Loss of Power Supply Probability-LPSP). However, the PMS has marginal effects on COE. The Electric to Thermal Load Ratio (ETLR) has no effects on COE for PV/Batt/ICE but strongly affects PV/Batt/MGT-based hybridised CHP systems. The higher thermal than the electric loads lead to higher efficiency and better environmental footprint. Results from this study also indicate that for a stand-alone hybridised system operating under FEL/FTL type PMS, the power only system has lower cost compared to the CHP and the Combined Cooling, Heating, and Power (CCHP) systems. This occurs at the expense of overall energy and exergy efficiencies. Additionally, the relative magnitude of heating and cooling loads have insignificant effects on COE for PV/Batt/ICE-based system configurations, however this substantially affects PV/Batt/MGT-based hybridised CCHP systems. Although there are no significant changes in the overall energy efficiency of CCHP systems in relation to variations to heating and cooling loads, systems with higher heating demand than cooling demand lead to better environmental benefits and renewable penetration at the cost of Duty Factor. Results also reveal that the choice of objective functions do not affect the system optimisation significantly.

The protection of plasma facing components from heat and particle overloads is paramount to ensure the operability and desired lifetime of magnetic fusion devices. The possibility of using external 3D magnetic perturbations to improve the steady-state heat exhaust in diverted tokamaks has been studied in this thesis. This approach involves producing a controlled stochastic region in the plasma edge without significantly affecting the core of the plasma. Using field line tracing and 3D advection-diffusion heat transport models, the resulting magnetic and heat flux footprints on the divertor have been analyzed. An optimized configuration has been obtained, which reveals the potential of this approach for considerably reducing the peak heat load on the divertor.<br>Att skydda plasmakomponenter mot höga värmeflöden och snabba partiklar är av största vikt föratt säkerställa funktionsduglighet och önskad livslängd för en magnetisk fusionsreaktor. Möjlighetenatt använda externa 3D-magnetiska störningar för förbättrad statisk värmeavledningeni tokamaker med magnetiska avledare har studerats i denna avhandling. Tillvägagångssättetinnebär att man producerar en kontrollerad stokastisk region i plasmakanten utan att väsentligtpåverka plasmakärnan. Med hjälp av fältlinjespårning och 3D-modellering av värmetransportsom en advektions-diffusionsprocess har de resulterande magnetiska fotspåren och värmeflödetpå avledaren analyserats. En optimerad konfiguration har erhållits, vilket visar potentialen i dettatillvägagångssätt för att avsevärt minska den maximala värmebelastningen på avledaren.

Climate change and energy efficiency has become a matter of concern in recent times; therefore, energy efficiency of buildings has drawn major attention. According to the European Commission, EU countries must improve energy efficiency of existing buildings by retrofitting and renovating the buildings. A case study of a renovated commercial building is considered in this degree project. A model of the building is developed in the IDA Indoor Climate and Energy (IDA ICE) software. The model is then augmented to include renovations in the building. Further, the model is simulated in IDA ICE before and after renovations to investigate the impact of renovations on energy consumption of the building for one year. The simulation results indicate peak demands of district heating that occur in the coldest days of the year. The peak demands of energy are expected to increase the district heating cost because they serve as a basis for new pricing model introduced by the energy providers. Hence, it is important from the customer point of view to reduce the peak loads for cost shavings. The project work also provides an insight into the alternative source of energy such as heat pumps to reduce the peak load demands of district heating.

The thesis deals with simulation of solar gains in highly glazed administration building of Microsoft company on Vyskocilova Street in Prague. Effects of the geographical orientation and types of shading are compared on the base of the current simulation. For a more precise description of the effect of geographical orientation is simulation of solar gains in fictive office room with constant dimension together with applying different types of shielding. All the simulations are performed in TRSNYS 16.1 software.

This study is conducted for the design and analysis of pressure vessels and associated pressurized equipment using various codes and methods. A computer software is developed as the main outcome of this study, which provides a quick and comprehensive analysis by using various methods utilized in codes and standards together with theoretical and empirical methods which are widely accepted throughout the world. Pressure vessels are analyzed using ASME Boiler and Pressure Vessel Code, whereas auxiliary codes, especially ASCE and AISC codes are utilized for structural analyses of these equipment. Effect of wind, seismic, and other types of loadings are also taken into consideration in detail, with dynamic analyses. Support structures and their auxiliary components are also items of analysis. Apart from pressure vessels, many pressurized process equipments that are commonly used in the industy are also included in the scope of the study. They include safety valves which are an integral part of those kinds of pressurized or enclosed systems, two of the heat exchanger components with great importance -tubesheets and expansion joints-, and API 650 tanks for oil or water storage. The computer software called as VESSELAID is written in Microsoft Visual Basic 6.0 using SI units. Design and analysis methods of VESSELAID are based on various code rules, recommended design practices and alternative approaches.

This thesis deals with the heat loss and the heat loads simulation of A1 building in the area of The Faculty of Mechanical Engineering, Brno University of Technology and with the measures of the energy saving. The measures of the thermo-technical charakteristics for the winter and summer operations are provided on the base of the current state simulation. These measures include increasing of thermal resistence (of the building case), the radiation shielding, the sun blinds and the passive cooling by the night ventilation. All the simulation are performed in TRNSYS 16.1 software.

Cette thèse exploratoire pose les bases scientifiques et méthodologiques d’une approche transversale visant à étudier l’énergétique urbaine et le bio-climatisme. Elle fait appel à des concepts et des outils de l’architecture et l’urbanisme, et à la physique du bâtiment et de la ville. Cette thèse étudie les relations entre la morphologie urbaine et les processus aérodynamiques qui se développent dans la canopée urbaine et leurs effets sur la demande énergétique des bâtiments induite par les infiltrations d’air et les échanges thermiques convectifs. Les spécificités de l’aérodynamique et de la physique urbaines sont d’abord synthétisées et la morphologie de tissus urbains réels est analysée. Une typologie générique de bâtiments isolés et une autre d’îlots urbains en sont déduites. Le modèle CFD est ensuite validé par comparaison des prédictions du modèle avec des résultats expérimentaux et numériques, et des expérimentations numériques sont réalisées sur les différents types morphologiques. Les écoulements moyens sont analysés dans leurs rapports avec la morphologie bâtie, et la distribution des coefficients de pression sur les façades des bâtiments est analysée. Ensuite, les échanges thermiques sont couplés aux processus aérodynamiques. L’amélioration des estimations des échanges convectifs des bâtiments grâce à la CFD est vérifiée par comparaison des résultats de simulation avec des données expérimentales et numériques, ainsi qu’avec les valeurs standard. Une adaptation des fonctions de paroi relatives au transfert thermique est proposée sur la base d’études existantes, et la distribution des échanges convectifs sur les façades de bâtiments est analysée. Enfin, la demande énergétique des bâtiments due aux infiltrations d’air et à la transmission de chaleur au travers de leur envelope est estimée pour différents types morphologiques, et comparée avec les valeurs estimées suivant une approche réglementaire. Les résultats de cette thèse mettent en évidence les effets des propriétés topologiques et métriques des bâtiments et ensembles bâtis sur le développement de recirculations d’air dans la canopée urbaine. Celles-ci induisent une distribution et intensité hétérogènes des coefficients de pression et d’échange convectif sur les façades des bâtiments, qui influent sur le comportement thermique des bâtiments non isolés et perméables à l’air. Par ailleurs, l’estimation de leur demande énergétique diffère suivant si celle-ci est basée sur les valeurs simulées ou standard des coefficients de pression et d’échange convectif. Cependant, l’influence relative de la structure bâtie sur la demande énergétique des bâtiments apparaît plus importante pour les bâtiments isolés thermiquement. La différence entre la demande énergétique par unité de surface de plancher, due aux infiltrations d’air et pertes thermiques au travers de l’enveloppe peut varier de 18% à 47% suivant si le bâtiment est isolé ou situé dans un environnement bâti<br>This thesis is an exploratory study that lays the scientific and methodological foundations of a transverse approach for studying urban energy and bio-climatic issues. This approach involves concepts and tools of building and urban physics as well as urban planning and architecture. It addresses the relations between urban morphology and aerodynamic processes, and studies their effects on the building energy loads due to infiltration and convective heat losses. This thesis is divided into three main parts. The first part synthesizes the specificities of urban aerodynamics and urban physics, and analyzes existing urban fabrics from a morphological point of view. Generic typologies of isolated buildings and urban blocks for small scale aerodynamic studies are deduced. The second part validates the computational fluid dynamics (CFD) model (steady RANS RSM) against detailed experimental and numerical data, and presents the numerical experiments performed on the different morphological types. Mean flow structures that develop according to the construction shape and built environment, as well as pressure distribution on the building outer walls are examined. The last part couples heat and air fluxes to evaluate the contribution of urban air flows on the building energy loads. The improvement brought by CFD to the assessment of building convective heat transfers is verified by comparing numerical results to experimental data, detailed numerical studies and standard correlations. An enhanced temperature wall-function adapted for forced convection problems is adjusted to the model based on existing studies, and the convective heat transfers distribution on building facades is analyzed. Finally, the building energy loads due to air infiltration and heat transmission are estimated for typical constructions and compared to standard values. The results of this thesis show strong effects of the topology and dimensionality of constructions and urban structures on the development of recirculation phenomena within the urban canopy layer. The related aerodynamic conditions yield heterogeneous pressure and convective heat transfer intensities and distributions on building facades, which depend upon the considered built morphology. Their effects on building energy loads are logically particularly important in absolute value for buildings that are neither insulated nor air tight. Nonetheless, the estimates of the building energy needs based on standard or simulated pressure and convective heat transfer coefficients often show substantial deviation. Focusing on the relative contribution of the built structure, the effects of the aerodynamic context appear more influential for insulated buildings. Essentially, switching from an exposed to a sheltered building may decrease the energy needs per surface unit of floor due to air infiltration and heat transmission through outer walls by 18% up to 47% according to simulation

Les futurs réacteurs expérimentaux comme ITER ou JT-60SA réaliseront des réactions de fusion thermonucléaire au sein de plasmas de plusieurs millions de degrés. Le confinement de la réaction au centre de la chambre est assuré par des champs magnétiques très intenses générés par des aimants supraconducteurs. Ces bobines sont refroidies à 4.4 K via une circulation forcée d’hélium supercritique. Le fonctionnement cyclique des machines engendre des charges thermiques pulsées qui devront être absorbées par les réfrigérateurs de plusieurs mégawatts de puissances électriques. L’expérience HELIOS, construite au CEA Grenoble, est une maquette à échelle réduite du système de distribution d’hélium du tokamak JT-60SA constituée d’un bain d’hélium à saturation et d’une boucle en hélium supercritique. Les travaux de thèse présentés ici explorent les possibilités d’HELIOS afin de réaliser les études expérimentale et numérique de trois stratégies de lissage de charges thermiques : l’utilisation du bain saturé en tant que volant thermique ouvert, la variation de la vitesse du circulateur et l’utilisation de la vanne de by-pass de la charge thermique. Le modèle EcosimPro développé ici rend bien compte des phénomènes de couplage transitoire entre le dépôt d’énergie, la montée en pression et en température de la boucle de circulation, de même que le couplage entre la boucle de circulation et le bain saturé. Des contrôles avancés ont été testés numériquement puis validés expérimentalement pour améliorer la stabilité du réfrigérateur et optimiser la puissance de réfrigération<br>Future fusion reactor devices such as ITER or JT-60SA will produce thermonuclear fusion reaction inplasmas at several millions of degrees. The confinement in the center of the chamber is achieved byvery intense magnetic fields generated by superconducting magnets. These coils have to be cooleddown to 4.4 K through a forced flow of supercritical helium. The cyclic behavior of the machinesleads to pulsed thermal heat loads which will have to be handled by the refrigerator.The HELIOS experiment built in CEA Grenoble is a scaled down model of the helium distributionsystem of the tokamak JT-60SA composed of a saturated helium bath and a supercritical helium loop.The thesis work explores HELIOS capabilities for experimental and numerical investigations on threeheat load smoothing strategies: the use of the saturated helium bath as an open thermal buffer, therotation speed variation of the cold circulator and the bypassing of the heated section. Thedeveloped model describes well the physical evolutions of the helium loop (pressure, temperature,mass flow) submitted to heat loads observed during experiments. Advanced controls have beentested and validated to improve the stability of the refrigerator and to optimize the refrigerationpower

Structural engineers have traditionally detailed structures with structural and fabrication efficiency in mind, but often based on a limited understanding of thermal efficiency. Some connection designs can create significant thermal bridging, leading to unnecessary heat transfer and even premature degradation through condensation. Thermal bridging occurs when heat transfer is given a path through a more conductive material like concrete or steel rather than insulation. Concrete sandwich wall panels (SWP) tend to be highly efficient at preventing heat transfer in the middle of panels, with greatest heat transfer occurring at connections. This project identified thermally efficient details for future SWP construction to reduce heat transfer, lessen environmental impact, and increase sustainability of SWP structures. It can be particularly difficult to avoid thermal bridging at corbel connections, so 12 corbel specimens were created and tested to provide alternative corbel design options for engineers. Nine details were successfully created and are presented. Corbel specimens were modeled using the Beam-Spring Method with good agreement. After validating the Beam-Spring Model, a parametric study investigated effectiveness of the PCI Second Order Analysis and the effect of length, panel stiffness, and wythe configuration on SWP behavior under axial and flexural loads.

Master’s Thesis deals with utilization of energy simulation software in area of classic brick buildings and measures to decrease heat consumption. Introduction deals with historic development of heat loss demands in Czech Republic and ways how to decrease heat loss through different types of building elements. Next chapter is focused on indoor microclimate and it’s affecting factors. Last but not least are mentioned environmental and financial aspects of these adjustments. Final part shows examined buildings, simulation configurations and output evaluations.

Intense heat fluxes from the divertor incident on material surfaces represent a “bottleneck” problem for the next generation of tokamaks. Advanced divertors, such as the X-Divertor (XD) and Super X-Divertor (SXD), offer a magnetic solution to the heat flux problem by (a) increasing the plasma-wetted area via flux expansion at the targets, and (b) possibly opening regimes of stable, detached operation of the divertor via flux tube flaring, as quantified by the Divertor Index. The benefits of the XD and SXD are derived from their unique magnetic geometries, foregoing the need for excessive gas puffing or impurity injection to mitigate divertor heat fluxes. Using the CORSICA magnetic equilibrium code, XDs and SXDs appear feasible on current- and next-generation tokamaks, with no required changes to the tokamak hardware, and respecting coil conductor limits. Divertor heat and particle transport modeling is performed in SOLPS 5.1 for XD or SXD designs in NSTX-Upgrade, Alcator C-Mod, and CFNS/FNSF. Incident heat fluxes at the targets are kept well below 10 MW/m², even for narrow SOL widths in high-power scenarios. In C-Mod and CFNS, parallel temperature profiles imply the arrestment of the detachment front near the targets. Finally, an X-Divertor for ITER is presented.<br>text

碩士<br>國立勤益科技大學<br>冷凍空調系<br>101<br>In this study, centrifugal chillers of 1000 USRT with constant and varied speed in Chiayi area of Taiwan was investigated, respectively, in order to understand their operation efficiencies under different heat loads and different cooling temperatures. Through the simulation of the software, YORKWORK, it is found that the performance of the chiller with constant speed is superior to that of the chiller with varied speed while the operation condition is 100% heat load and the temperature of cooling water is above 27 ℃ or the operation condition is 90% heat load and the cooling temperature is above 30℃. From the simulation, it is also indicated that 4.7% efficiency difference between the two chillers can be reached under the operation conditions mentioned above. Except the operation conditions mentioned above, the performance of the chiller with varied speed is greater than that of the chiller with constant, the maximum efficiency difference of 40.46% can be obtained. Furthermore, from the experimental results, it is also shown that while the operation condition is above 80% heat load and cooling temperature is above 29℃, the efficiency of the chiller with constant frequency is 6.2% superior to that of the chiller with varied frequency. Except the operation condition mentioned above, the performance of the chiller with varied speed is always greater than that of the chiller with constant, the maximum efficiency difference of 49.8% can be obtained in experiments. From the measured energy consumption of individual constant and varied speed chillers,an optimum operation strategy for the HVAC system in a hospital of chiayi was developed. While the heat load of the system is higher and the ambient dry bulb temperature is opened to operate in full load condition as possible. While the heat load is lower and the ambient dry bulb temperature is under 29℃, the system tempt to open the varied speed chiller and shutdown the constant speed chiller. Through the optimum operation, the enery consumption of the system within a year is the lowest in comparison to the of the system operating under fully constant speed chillers or fully varied speed chillers.

The trend in the electronic and electrical equipment industry towards denser and more powerful product requires a higher level of performance from cooling devices. In this context, passive cooling techniques such as latent heat storage systems have attracted considerable attention in recent years. Phase change materials (PCMs) have turned out to be extremely advantageous in this regard as they absorb high amount of latent heat without much rise of temperature. But unfortunately, nearly all phase change materials (PCMs) with high latent heat storage capacity have unacceptably low thermal conductivity, which makes heating and cooling processes slow during melting and solidification of PCMs. Augmentation of heat transfer in a PCM is achieved by inserting a high thermal conductivity material, known as thermal conductivity enhancer (TCE), into the PCM. The conglomeration of PCM and TCE is known as a thermal storage unit (TSU). In this thesis, detailed and systematic analyses are presented on the thermal performance of TSUs subjected to two types of thermal loading- (a) constant power loading in which a constant power level is supplied to the chip (heater) for a limited duration of time, and (b) cyclic loading. Eicosane is used as the PCM, while aluminium pin or plate fins are used as TCEs. First, a 1-D analytical model is developed to obtain a closed-form temperature distribution for a simple PCM domain (without TCE) heated uniformly from the bottom. The entire heating process is divided into three stages, viz. (a) sensible heating period before melting, during which heat is stored in the solid PCM in the form of specific heat, (b) melting period, during which a melt front progresses from the bottom to the top layer of the PCM and heat is stored in latent as well as in sensible forms, and (c) post melting period, during which energy is stored again in the form of sensible heat. For each stage, conduction energy equation is solved with a set of initial and boundary conditions. Subsequently, a resistance capacitance model of phase change process is developed for further analysis. For transient performance under constant thermal loading, experimental investigations are carried out for TSUs with different percentages of TCE. A numerical model is developed to interpret the experimental results. The thermal performance of a TSU is found to depend on a number of geometrical parameters and boundary conditions. Hence, a systematic approach is desirable for finding the best TSU design for which the chip can be operated for a longer period of time before it reaches a critical temperature (defined as the temperature above which the chip starts malfunctioning). As a first step of the approach, it is required to identify the parameters which can affect the transient process. It is found that the convective heat transfer coefficient, ‘h’ and the exposed area for heat transfer have little effect on the chip temperature during the constant power operation. A randomized search technique, Genetic Algorithm (GA), is coupled with the CFD code to find an optimum combination of geometrical parameters of TSUs based on the design criteria. First, the optimization is carried out without considering melt convection within the PCM. It is found that the optimum half-fin width remains fixed for a given heat flux and temperature difference. Assuming a quasi steady process, the results of optimization are then explained by constructing and analyzing a resistance network model. The resistance network model is then extended to include the effect of melt convection, and it is shown that the optimum pitch changes with the strength of convection. Accordingly, numerical analysis is carried out by considering the effect of melt convection, and a correlation for optimum pitch is developed. Having established the role of melt convection on the thermal performance of TSUs, rigorous computational and experimental studies are performed in order to develop correlations among different non-dimensional numbers, such as Nusselt number, Rayleigh number, Stefan number and Fourier number, based on a characteristic length scale for convection. The enclosures are classified into three types, depending on the aspect ratio of cavity, viz. shallow, rectangular and tall enclosures. For a shallow enclosure, the characteristic length is the height of cavity whereas for a tall enclosure, the characteristic length is the fin pitch. In case of rectangular enclosure, both pitch and height are the important characteristic lengths. For cyclic operation, it is required that the fraction of the PCM melting during the heating cycle should completely solidify back during the cooling period, in order that that TSU can be operated for an unlimited number of cycles. If solidification is not complete during the cooling period, the TSU temperature will tend to rise with every cycle, thus making it un-operational after some cycles. It is found that the solidification process during the cooling period depends strongly on the heat transfer coefficient and the cooling surface area. However, heat transfer coefficient does not play any significant role during the heating period; hence a TSU optimized for transient operation may not be ideal for cyclic loading. Accordingly, studies are carried out to find the parameters which could influence the behaviour of PCM under cyclic loading. A number of parameters are identified in the process, viz. cycle period and heat transfer coefficient. It is found that the required heat transfer coefficient for infinite cyclic operation is very high and unrealistic with air cooling from the surface of the TSU. Otherwise, the required cooling period for complete re-solidification will be very high, which may not be suitable for most applications. In an effort to bring down the cooling period to a duration that is comparable to the heating period, a new design is proposed where both ‘h’ and area exposed to heat transfer can be controlled. In this new design, the gaps between the fins in a plate-fin TSU are alternately filled with PCM, such that only one side of a fin is in contact with PCM and the other side is exposed to the coolant (air). In this arrangement, the same heat flow path through the fin which is used for heating the PCM (during the heating stage) can also be used for cooling and solidifying the PCM during the cooling part of the cycle. Natural or forced air cooling through the passages can be introduced to provide a wide range of heat transfer coefficient which can satisfy the cooling requirements. With this arrangement, the enhanced area provided for cooling keeps the ‘h’ requirement within a realistic limit. This cooling method developed is categorized as a combination of active and passive cooling techniques. Analytical and numerical investigations are carried out to evaluate the thermal performance of this modified PCM-based heat sink in comparison to the ones with conventional designs. It is found that, the performance of new PCM-based heat sink is superior to that of the conventional one. Experiments are performed on both the conventional and the new PCM-based heat sinks to validate the new findings.

The trend in the electronic and electrical equipment industry towards denser and more powerful product requires a higher level of performance from cooling devices. In this context, passive cooling techniques such as latent heat storage systems have attracted considerable attention in recent years. Phase change materials (PCMs) have turned out to be extremely advantageous in this regard as they absorb high amount of latent heat without much rise of temperature. But unfortunately, nearly all phase change materials (PCMs) with high latent heat storage capacity have unacceptably low thermal conductivity, which makes heating and cooling processes slow during melting and solidification of PCMs. Augmentation of heat transfer in a PCM is achieved by inserting a high thermal conductivity material, known as thermal conductivity enhancer (TCE), into the PCM. The conglomeration of PCM and TCE is known as a thermal storage unit (TSU). In this thesis, detailed and systematic analyses are presented on the thermal performance of TSUs subjected to two types of thermal loading- (a) constant power loading in which a constant power level is supplied to the chip (heater) for a limited duration of time, and (b) cyclic loading. Eicosane is used as the PCM, while aluminium pin or plate fins are used as TCEs. First, a 1-D analytical model is developed to obtain a closed-form temperature distribution for a simple PCM domain (without TCE) heated uniformly from the bottom. The entire heating process is divided into three stages, viz. (a) sensible heating period before melting, during which heat is stored in the solid PCM in the form of specific heat, (b) melting period, during which a melt front progresses from the bottom to the top layer of the PCM and heat is stored in latent as well as in sensible forms, and (c) post melting period, during which energy is stored again in the form of sensible heat. For each stage, conduction energy equation is solved with a set of initial and boundary conditions. Subsequently, a resistance capacitance model of phase change process is developed for further analysis. For transient performance under constant thermal loading, experimental investigations are carried out for TSUs with different percentages of TCE. A numerical model is developed to interpret the experimental results. The thermal performance of a TSU is found to depend on a number of geometrical parameters and boundary conditions. Hence, a systematic approach is desirable for finding the best TSU design for which the chip can be operated for a longer period of time before it reaches a critical temperature (defined as the temperature above which the chip starts malfunctioning). As a first step of the approach, it is required to identify the parameters which can affect the transient process. It is found that the convective heat transfer coefficient, ‘h’ and the exposed area for heat transfer have little effect on the chip temperature during the constant power operation. A randomized search technique, Genetic Algorithm (GA), is coupled with the CFD code to find an optimum combination of geometrical parameters of TSUs based on the design criteria. First, the optimization is carried out without considering melt convection within the PCM. It is found that the optimum half-fin width remains fixed for a given heat flux and temperature difference. Assuming a quasi steady process, the results of optimization are then explained by constructing and analyzing a resistance network model. The resistance network model is then extended to include the effect of melt convection, and it is shown that the optimum pitch changes with the strength of convection. Accordingly, numerical analysis is carried out by considering the effect of melt convection, and a correlation for optimum pitch is developed. Having established the role of melt convection on the thermal performance of TSUs, rigorous computational and experimental studies are performed in order to develop correlations among different non-dimensional numbers, such as Nusselt number, Rayleigh number, Stefan number and Fourier number, based on a characteristic length scale for convection. The enclosures are classified into three types, depending on the aspect ratio of cavity, viz. shallow, rectangular and tall enclosures. For a shallow enclosure, the characteristic length is the height of cavity whereas for a tall enclosure, the characteristic length is the fin pitch. In case of rectangular enclosure, both pitch and height are the important characteristic lengths. For cyclic operation, it is required that the fraction of the PCM melting during the heating cycle should completely solidify back during the cooling period, in order that that TSU can be operated for an unlimited number of cycles. If solidification is not complete during the cooling period, the TSU temperature will tend to rise with every cycle, thus making it un-operational after some cycles. It is found that the solidification process during the cooling period depends strongly on the heat transfer coefficient and the cooling surface area. However, heat transfer coefficient does not play any significant role during the heating period; hence a TSU optimized for transient operation may not be ideal for cyclic loading. Accordingly, studies are carried out to find the parameters which could influence the behaviour of PCM under cyclic loading. A number of parameters are identified in the process, viz. cycle period and heat transfer coefficient. It is found that the required heat transfer coefficient for infinite cyclic operation is very high and unrealistic with air cooling from the surface of the TSU. Otherwise, the required cooling period for complete re-solidification will be very high, which may not be suitable for most applications. In an effort to bring down the cooling period to a duration that is comparable to the heating period, a new design is proposed where both ‘h’ and area exposed to heat transfer can be controlled. In this new design, the gaps between the fins in a plate-fin TSU are alternately filled with PCM, such that only one side of a fin is in contact with PCM and the other side is exposed to the coolant (air). In this arrangement, the same heat flow path through the fin which is used for heating the PCM (during the heating stage) can also be used for cooling and solidifying the PCM during the cooling part of the cycle. Natural or forced air cooling through the passages can be introduced to provide a wide range of heat transfer coefficient which can satisfy the cooling requirements. With this arrangement, the enhanced area provided for cooling keeps the ‘h’ requirement within a realistic limit. This cooling method developed is categorized as a combination of active and passive cooling techniques. Analytical and numerical investigations are carried out to evaluate the thermal performance of this modified PCM-based heat sink in comparison to the ones with conventional designs. It is found that, the performance of new PCM-based heat sink is superior to that of the conventional one. Experiments are performed on both the conventional and the new PCM-based heat sinks to validate the new findings.

M.Ing.<br>Dry air cooled heat exchangers form a vital part of industrial heat transfer systems, especially in countries where the supply and availability of clean cooling water is limited. Headerboxes are rectangular pressure vessels that act as the inlet distribution and outlet collection devices. As rectangular pressure vessels, headerboxes are subject to design codes such as ASME (ASME Section VIII, Division 1, 2007). Unfortunately ASME (ASME Section VIII, Division 1, 2007) offers no guidance on how to allow for the effect of external loads applied to the headerbox through the vessel’s nozzles. This creates a difficult situation, since vessel designers are mandated by ASME to consider the effects of nozzle loads by American Petroleum Institute standard 661 (API, 2006). The aim of this project was therefore to develop a closed form design methodology that accurately predicts the stresses inside a headerbox that is subject to external loadings as well as internal pressure. After extensive research it was decided that the only viable approach would be to extend ASME’s rigid frame theory. This was done, and a new set of equations describing the stress distribution inside a headerbox were derived. These equations were then tested using 2D Finite Element Analysis (FEA) to determine whether they represented the reality of the 2D model they described. It was found that the equations were accurate enough in 2D and the next step was to test the model experimentally and using full 3D FEA. A local manufacturer of air cooled heat exchangers was approached and they helped design an experimental specimen and agreed to fund its construction. Unfortunately, due to time constraints, it was not possible to build and test the specimen experimentally. The specimen geometry was then analysed using the Abaqus (Dassault Systѐmes Simulia Corp., 2010) FEA package. The 3D FEA analysis considered several different load cases. After carefully analysing the results it was seen that the rigid frame model could make useful qualitative statements about the effects of the nozzle loads, but it performed poorly as a quantitative prediction method. However, since the effects of the nozzle loads are generally quite small it is possible that, with appropriate safety factors, the rigid frame model could be used as a conservative design methodology. The usefulness of a commonly used empirical guideline was also examined. This project is far from conclusive and much more work is required to fully examine the usefulness of rigid frame theory. That being said, this project has made important steps towards a more complete understanding of rectangular pressure vessels and has shown possible ways forward.

The temperature differential of chilled water is an important factor used for evaluating the performance of a chilled water system. A low delta-T may increase the pumping energy consumption and increase the chiller energy consumption. The system studied in this thesis is the chilled water system at the Dallas/Fort Worth International Airport (DFW Airport). This system has the problem of low delta-T under low cooling loads. When the chilled water flow is much lower than the design conditions at low cooling loads, it may lead to the laminar flow of the chilled water in the cooling coils. The main objective of this thesis is to explain the heat transfer performance of the cooling coils under low cooling loads. The water side and air side heat transfer coefficients at different water and air flow rates are calculated. The coefficients are used to analyze the heat transfer performance of the cooling coils at conditions ranging from very low loads to design conditions. The effectiveness-number of transfer units (NTU) method is utilized to analyze the cooling coil performance under different flow conditions, which also helps to obtain the cooling coil chilled water temperature differential under full load and partial load conditions. When the water flow rate drops to 1ft/s, laminar flow occurs; this further decreases the heat transfer rate on the water side. However, the cooling coil effectiveness increases with the drop of water flow rate, which compensates for the influence of the heat transfer performance under laminar flow conditions. Consequently, the delta-T in the cooling coil decreases in the transitional flow regime but increases in the laminar flow regime. Results of this thesis show that the laminar flow for the chilled water at low flow rate is not the main cause of the low delta-T syndrome in the chilled water system. Possible causes for the piping strategy of the low delta-T syndrome existing in the chilled water system under low flow conditions are studied in this thesis: (1) use of two way control valves; and (2) improper tertiary pump piping strategy.

Statistical Method to Define Rational Heat Loads on Railway Air Conditioning System for Changeable Climatic Conditions / A. Radchenko, M. Radchenko, E. Trushliakov, S. Kantor, V. Tkachenko // 5th Intern. Conf. on Systems and Informatics (ICSAI). – Nanjing, 2019. – P. 1294–1298<br>A statistical method of defining rational heat loads on railway air conditioning system with taking into account the current changeable heat loads corresponding to current climatic conditions on the route lines has been proposed. According to this method the rational designed heat load on refrigeration machine, matching current changeable climatic conditions on the route lines and providing efficient operation of refrigeration machine of air conditioning system with maximum (close maximum) refrigeration capacity production (refrigeration output) for definite period of operation (monthly, seasonal or annular period) is defined through statistical treatment of data sets of hourly refrigeration capacities corresponding to the current climatic conditions on the route lines by their summation during the operation period for various installed (designed) refrigeration capacities of machine. The method is based on the hypothesis of different rates of refrigeration capacity production increment for the period of operation with increasing the installed refrigeration capacity, that is revealed in slowing down the rate of refrigeration capacity production increment at over increased installed refrigeration capacity. Proceeding from this hypothesis the rational value of heat load on railway air conditioning system is chosen close to the value that corresponds to the maximum refrigeration capacity production for the period of operation. Such rational value of designed heat load on railway air conditioning system provides reduction of refrigeration machine capacity and its cost by 15…20 % as compared with traditional its designing for the maximum heat load. The operation of refrigeration machine in partial modes for enlarged installed refrigeration capacity chosen traditionally – for the maximum heat load needs application of expensive inventor compressors to control motor speed matching current changeable heat loads.

With the rise in hazards that structures are potentially subjected to these days, ranging from pre-contemplated terror attacks to accidental and natural disasters, safeguarding structures against such hazards has increasingly become a common design requirement. The extreme loading conditions associated with these hazards renders the concept of imposing generalized codes and standards guidelines for structural design unfeasible. Therefore, a general shift towards performance-based design is starting to dominate the structural design field. This study introduces a powerful structural analysis tool for reinforced concrete structures, possessing a high level of reliability in handling a wide range of typical and extreme loading conditions in a sophisticated structural framework. VecTor3, a finite element computer program previously developed at the University of Toronto for nonlinear analysis of three-dimensional reinforced concrete structures employing the well-established Modified Compression Field Theory (MCFT), has been further developed to serve as the desired tool. VecTor3 is extended to include analysis capabilities for extreme loading conditions, advanced reinforced concrete mechanisms, and new material types. For extreme loading conditions, an advanced coupled heat and moisture transfer algorithm is implemented in VecTor3 for the analysis of reinforced concrete structures subjected to fire. This algorithm not only calculates the transient temperature through the depth of concrete members, but also calculates the elevated pore pressure in concrete, which enables the prediction of the occurrence of localized thermally-induced spalling. Dynamic loading conditions are also extended to include seismic loading, in addition to blast and impact loading. Advancing the mechanisms considered, VecTor3 is developed to include the Disturbed Stress Field Model (DSFM), dowel action and buckling of steel reinforcement bars, geometric nonlinearity effects, strain rate effects for dynamic loading conditions, and the deterioration of mechanical properties at elevated temperatures for fire loading conditions. Finally, the newly-developed Simplified Diverse Embedment Model (SDEM) is implemented in VecTor3 to add analysis capability for steel fibre-reinforced concrete (SFRC). Various analyses covering a wide range of different structural members and loading conditions are carried out using VecTor3, showing good agreement with experimental results available in the literature. These analyses verify the reliability of the models, mechanisms, and algorithms incorporated in VecTor3.