Дисертації з теми "Cooling solutions"
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Khachaturian, Mark Haig 1979. "Solutions to various problems in reversible cooling fMRI studies." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/17030.
Повний текст джерелаIncludes bibliographical references (p. 40).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Functional magnetic resonance imaging (fMRI) has been very useful in helping neuroscientists map the brain. One tool to investigate the interactions between brain regions is to disable a small region in the brain, and look at the functional consequences of this (reversible) inactivation upon regions anatomically connected to the inactivated site. A number of issues need to be resolved before the reversible cooling technique can be used in fMRI studies. The solutions to a number of problems directly related to using reversible inactivation by cooling in conjunction with fMRI experiments on monkey brains are presented in this thesis. Specifically, these include (1) designing a cooling system and cooling probe capable of reversibly cooling the surface cortex of the monkey's brain, (2) develop or use an existing method to measure the temperature distribution with the MR-scanner, and (3) design and construct a coil (phase array) that will be used to obtain temperature and fMRI data at the highest resolution possible. A cooling system and coolant probe were designed capable of changing the temperature of the surface cortex from 37 oC to 20 oC. The Proton Resonance Frequency Shift method, which calculates the temperature based on the phase change between two images, was used to measure the temperature distribution inside an object using an fMRI sequence similar to the one that will be used in the actual experiment. The method was tested and showed an accuracy of ± 0.6 oC as compared with concurrent thermocouple measurements when adjusted for phase drift. A precision of ± 0.15 oC was found at a resolution of 2.1 x 2.1 x 1.0 mm3. A phase array head coil was designed with superior imaging qualities to the current single coil. An increase of SNR from 40 to 52 was observed in the image (30% increase) as compared with the theoretical calculated increase of 70%.
by Mark Haig Khachaturian.
S.M.
Chou, Lu-chien. "Drag reducing cationic surfactant solutions for district heating and cooling systems /." The Ohio State University, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487758178238587.
Повний текст джерелаLambert, Océane. "Solutions architecturées par fabrication additive pour refroidissement de parois de chambres de combustion." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI048/document.
Повний текст джерелаCombustion chamber walls are perforated with holes so that a cooling air flow can be injected through them. The wall is cooled by convection and an insulating film is created on the hot surface (film cooling). This PhD thesis aims to use the possibilities of additive manufacturing to provide new architectured solutions that could enhance the internal heat exchanges, and lead to a higher cooling effectiveness.The first approach is to develop new designs of multiperforated walls by Electron Beam Melting (EBM) and Selective Laser Melting (SLM) used at the resolution limits of the processes. They are characterized by microscopy, X-ray tomography and permeability tests. Some aerothermal simulations help understanding the effects of these new designs on the flow and on heat exchanges. These results lead to a geometry adaptation.The second approach is to simultaneously manufacture an architectured part with dense and porous zones by EBM. Thanks to image analysis combined with large field EBSD, it is possible to investigate the mechanisms leading to the porous zones and to link them to permeability and porosity. The film cooling effect could be favoured by the orientation of pores towards the cooling flow. Therefore, a new powder-based manufacturing process named Magnetic Freezing, where metallic powders organize into an oriented structure thanks to a magnetic field, is developed.The various solutions studied during this thesis are tested on an aerothermal bench. They all show a more efficient and homogeneous cooling than the industrial reference. Some first tests on one of the selected solutions are performed on a combustion bench. This lighter and more permeable structure proves to be a solution as efficient as the industrial reference at a given flow rate. It should therefore be a more efficient solution for a given overpressure
Zhou, Jian Ming. "A multi-grid method for computation of film cooling." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/29414.
Повний текст джерелаScience, Faculty of
Mathematics, Department of
Graduate
Vattøy, Bjørnar. "Techno-economic evaluation of heat-driven cooling solutions for utilization of district heat in Aalesund, Norway." Thesis, KTH, Energiteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-245232.
Повний текст джерелаStudiens syfte är att utvärdera den tekno-ekonomiska genomförbarheten av att implementera värmedrivna kylelösningar i byggnader knytna till Tafjord Kraftvarme’s fjärrvärmenetvärk i Aalesund, Norge. Uppvärmnings- och nerkylningskrav hittades vid at projictera två 4000 𝑚2 kontorsbyggnader enligt “Passive House and Low Energy Building” kriterier, inom ramen av energikrav i TEK 17 byggnadsförordningar (Standard Norge, 2012) (Norwegian Building Authority, 2017). Passande nerkylnings- och uppvärmingsutrustning, både elektrisk och värmedriven, blev dimensionerande baserad på toppbelastning till de projicerade byggnader, och den tekniska och ekonomiska information tagen från utrustningsdistributörerna. LCOE-analysen visar att den värmedrivna nerkylningslösningen kan vara konkurrenskraftig ekonomisk sett, i variabel utstreckning, med de elektriska drivna lösningarna om varmebehovet är lågt eller vid at använda subventioner eller prisnedsättning på fjärrvarme som används för kylning. Nerkylningslösningen med torkmedel kan även vara konkurrenskraftig med den elektrisk drivna även utan subventioner eller prisnedsättning på fjärrvarme. Det är huvudsakligen på grund av dens förbättrade värmeåterhämtning som reducerar uppvärmningskraven. Absorptionskylaren å andra sidan, har både högre ströminmatning av fjärrvarme medan den är i gång och är därför mindre konkurrenskraftig utan subventioner eller prisnedsättning på fjärrvarme som används för kylning. I de utforskade byggnadsfallen kräver absorptionskylaren antigen subventioner eller prisnedsättning på fjärvarme för att kunna konkurrera med den elektriska kylmaren, medan det krävs både för att kunna konkurrera med värmepumpelösningen. Med ökande uppvärmingskrav blir de värmedrivna lösningarna som använder fjärrvarme som värmekälla mindre konkurrenskraftiga jämfört med värmepumpelösningarna. Detta på grund av de milda vintrar i Aalesund som leder till att värmepumparna kan köra med en COP på 2-3 medan den anses vara 1 for lösningarna som brukar fjärrvarme. Andra viktiga faktorer som inte ingår i LCOE-analysen är pålitlighet och miljöaspekten. Ingen av de värmedrivna nerkylningslösningarna andvänder något miljöovänligt köldmedium och underhållet av nerkyningsmaskiner är minimalt. Maskinernas livsläng är beräknad till 20 år för torkmedelkylaren och 40 år för absorptionskylaren, jämfört med 15 år för värmepumparna och den elektriska kylaren. De värmedrivna nerkylningslösningarna kan därför anses vara mer pålitliga både beträffande reglering av köldmedium och underhåll samt livslängd. Ytterligare en viktig faktor är att de värmedrivna nerkylningslösningarna, jämfört med värmepumplösningarna, kan vara et livskraftig alternativ, både med hänsyn til den ekonomiska faktoren, miljöfaktoren och pålitligheten och borde därför tas hänsyn till vid implementering av uppvärmings- og nerkylningsutrustning i byggnader knytna till fjärrvärmenätet.
Narvaez, Javier Artemio. "Evaluation of Alumina Nanofluids and Surfactant Drag Reducing Solutions to Improve Heat Transfer for Aircraft Cooling Systems." University of Dayton / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=dayton154479500350447.
Повний текст джерелаRabhi, Achref. "Numerical Modelling of Subcooled Nucleate Boiling for Thermal Management Solutions Using OpenFOAM." Licentiate thesis, Mälardalens högskola, Akademin för ekonomi, samhälle och teknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-53307.
Повний текст джерелаDavin, Tanguy. "Refroidissement des moteurs électriques : exploration des solutions à huile de lubrification." Thesis, Valenciennes, 2014. http://www.theses.fr/2014VALE0003/document.
Повний текст джерелаElectric motor is one of the most important elements of an electric vehicle. Some elements, particularly the windings, can be affected by rising heat. External cooling, as water jacket in the case, appears to be limited because the losses generated in windings must pass through zones where conduction is very poor. Cooling in the core of the machine is preferable, but heat transfer with air is poor. Due to the presence of lubricating oil in the vicinity of the motor and the heat transfer enhancement that such a liquid provides, oil circulation on the windings has been considered.The research was first dedicated to an extensive bibliography on the different solutions of motor cooling. Then heat transfer within the motor was modelled by using the lumped system analysis. Thanks to a sensitivity analysis, the main parameters affecting temperature have been identified before cooling systems were modelled. Finally, tests were performed on a specially designed bench. Oil was introduced at each side of the machine to directly cool the stator coil end-windings. Several oil injection patterns were tested. The influence of the oil flow rate, rotation speed and oil temperature has been investigated.The objective of this PHD study is to analyse all the thermal issues related to the oil cooling systems. This is a comparative study of the performance of the oil cooling solutions. Comparison is also done with conventional water cooling
Barthe, Stephanie Cecile. "Investigation and modeling of the mechanisms involved in batch cooling crystallization and polymorphism through efficient use of the FBRM." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24752.
Повний текст джерелаCommittee Chair: Dr Rousseau, Ronald W; Committee Co-Chair: Dr Grover Gallivan, Martha; Committee Member: Dr Realff, Matthew; Committee Member: Dr Garmestani, Hamid; Committee Member: Dr Nenes, Athanasios.
Smith, Bryan C. "Flow birefringence, nuclear magnetic resonance and corrosion measurements on drag reducing cationic surfactant solutions for district heating and cooling systems /." The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487780865409286.
Повний текст джерелаМандибура, В., та Ратушняк Г. С. "Шляхи зниження енергоспоживання при виробництві штучного холоду". Thesis, ВНТУ, 2018. http://ir.lib.vntu.edu.ua//handle/123456789/20971.
Повний текст джерелаA review of the engineering solutions of refrigeration systems, which are most often used in the design of cooling systems for industrial objects. The advantages and disadvantages as well as ways to improve the efficiency of cooling systems are considered.
ARRAGATTU, PRAVEEN KUMAR. "OPTIMAL SOLUTIONS FOR PRESSURE LOSS AND TEMPERATURE DROP THROUGH THE TOP CAP OF THE EVAPORATOR OF THE MICRO LOOP HEAT PIPE." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1152120112.
Повний текст джерелаMessias, Francisco Egidio. "Análise da influência da concentração e temperatura nas características de resfriamento das soluções do sal AWS-20 usados na têmpera." Universidade de São Paulo, 1998. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-15092016-121557/.
Повний текст джерелаThe determination of the cooling curves as alternative for analysis of the quenching media used in the heat treatments of hardening, is shown as one of the most powerful and efficient methods to evaluate and/or to quantify the quench severity of the quenchant.. Thus, the solutions of salt AWS-20 tested as quenching media, had its, acting evaluated by the traditional methods as profile of the distribution of hardness in test bodies and analysis metallographic and also through its cooling curves. The obtained results allowed the suggestion of a work strip for temperature and concentration with excellent revenue and being confirmed by the method of analysis of the cooling curves.
Costanzo, Matteo. "Adapting building design to climate change for an office building in Stockholm through solar control techniques." Thesis, KTH, Hållbara byggnader, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-287452.
Повний текст джерелаKlimatförändringar kommer att påverka många mänskliga aktiviteter och sektorer. Bland dem kommer den byggda miljön att möta flera utmaningar med avseende på de olika klimatförhållandena. Denna studie undersökte effekterna av den globala uppvärmningen på energibehovet och inomhusklimatkomforten för en kontorsbyggnad i Stockholm. Med hänsyn till en livslängd på 50 år undersöktes de framtida klimatförhållandena för ökningen av lufttemperaturen utomhus till 2070, i enlighet med det medelprognoserade växthusgasutsläppsscenariot som tillhandahålls av International Panel on Climate Change (IPCC). En annan klimatförändringsmetod antogs för att utveckla klimatfilen för år 2080 med tanke på variationen i alla väderparametrar. Tre olika passiva kyllösningar, såsom utvändigt solskydd (vertikalmarkis med screenväv), elektrokromt glas och invändigt ventilerat solskydd, har implementerats i fallstudiebyggnaden för att minska kylbehovet. Karaktären av strategierna utvärderades preliminärt och implementerades sedan i programvaran för byggenergisimulering IDA-ICE för att utvärdera energiprestanda med avseende på de olika klimaten. Resultaten indikerade att en ökning av kylbehovet och en minskning av värmeanvändningen kommer att ske i framtiden. De olika klimatförändringsmetoderna visade de inneboende/medföljande osäkerheterna när framtida utvärderingar utförs, även om liknande vädermönster hittades. De passiva kyllösningarnas reducering av total solenergitransmission, såsom införandet av frånluftsutsug och den elektrokroma tekniken, innebar en lägre kyl- och ventilationsanvändning. EC-tekniken rapporterade det lägsta kylbehovet, medan det invändiga ventilerade solskyddet överträffade de andra när det gäller årlig energiförbrukning.
Sinha, Ashish. "An adsorption based cooling solution for electronics used in thermally harsh environments." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/37077.
Повний текст джерелаWilson, Scott E. "Investigation of Copper Foam Coldplates as a High Heat Flux Electronics Cooling Solution." Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6944.
Повний текст джерелаTseitlin, Musii, and Valentina Raiko. "Ratio between heat and mass transfer when concentrating the solution in a cooling tower." Thesis, Lviv Polytechnic National University, 2019. http://repository.kpi.kharkov.ua/handle/KhPI-Press/42106.
Повний текст джерелаДосліджено співвідношення між інтенсивністю масопереносу в газі та передачею тепла в рідині під час концентрації випарного розчину. Встановлено, що частка опору рідини в загальному опорі переносу ентальпії зростає в діапазоні температур від 30 до 50 ° С майже в 2 рази, досягає 40%. Розроблена методика для окремого визначення коефіцієнтів масопереносу в газі і теплопередачі в рідині.
Al-Marri, Mohd Jaber F. A. "Modelling the solution crystallisation of L-gluatmic acid as prepared via reactive and cooling crystallisation." Thesis, University of Leeds, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.545682.
Повний текст джерелаYalcin, Fidan Seza. "Cfd Analysis Of A Notebook Computer Thermal Management Solution." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609483/index.pdf.
Повний текст джерелаs specifications. The different heat dissipation paths that are utilized in the design are investigated. Two active fans and aluminum heat dissipation plates as well as the heat pipe system are modeled according to their specifications. The first and second order discretization schemes as well as two different mesh densities are investigated as modeling choices. Under different operating powers, adequacy of the existing thermal management system is observed. Average and maximum temperatures of the internal components are reported in the form of tables. Thermal resistance networks for five different operating conditions are obtained from the analysis of the CFD simulation results. Temperature distributions on the top surface of the chassis where the keyboard and touchpad are located are investigated considering the user comfort.
Strömqvist, Bodil. "Fjärrvärmedriven Absorptionskyla : En ekonomisk undersökning av olika spetslösningar." Thesis, Mittuniversitetet, Institutionen för elektronikkonstruktion, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-42412.
Повний текст джерелаCastillo, Garcia Lorenzo. "Développement d’un outil de simulation dynamique pour la conception d’une solution de climatisation solaire réversible." Thesis, Pau, 2016. http://www.theses.fr/2016PAUU3003/document.
Повний текст джерелаThis PhD thesis was carried on in the framework of the SCRIB project (“dispositif Solaire de Climatisation Réversible Intégré au Bâti”) led by the Helioclim company. This project is funded by the French government (“Investissements d’Avenir” operated by the French Agency for Energy and Environment, ADEME). The goal of this project is to develop a reversible solar cooling system which can respond to a set of thermal requirements in industrial and tertiary building sector (cooling system, heating system, industrial cooling system and domestic hot water). Thus an ammonia/water absorption chiller prototype, powered by innovative thermal solar concentrators, has been built. This absorption chiller has a GAX (Generator-Absorber heat eXchange) configuration.This PhD work focused on the development of a support tool for the conception and the control of such device. A software tool has been developed implementing knowledge-based model, which took into account the operating and design parameters of the absorption chiller. The key originalities of the proposed work are as follows:- The software has been designed in a modular way allowing the simulation of various absorption chiller configurations (single or multi-stage).- The thermodynamic properties of the mixture have been modeled by equation of state or excess Gibb’s energy model. The working fluids can then be changed easily.- A “Positive Flash” model allows the description of all the possible states (sub-cooled, super-heated, biphasic…) of the various streams which are all considered as multicomponent mixtures, without a priori assumptions.- The various devices (evaporator, absorber, valves, etc.) are modeled from balance equations (mass, energy). - The generator is modeled using the concept of theoretical plates. MESH equations (Mass balance, Equilibrium, Summation, Heat balance) have been written for each stage.- Both thermal and material inertia are considered.Simulation results obtained with this software have been successfully compared to an earlier published experimental study for a GAX configuration absorption chiller which used ammonia/water as working fluids. Thanks to this tool, the steady state and the transient behavior of the system submitted to a perturbation can be simulated, which can be helpful for the development of the control policy of the absorption chiller
He, Bo. "High-Capacity Cool Thermal Energy Storage for Peak Shaving - a Solution for Energy Challenges in the 21st century." Doctoral thesis, KTH, Chemical Engineering and Technology, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3781.
Повний текст джерелаDue to climatic change, increasing thermal loads inbuildings and rising living standards, comfort cooling inbuildings is becoming increasingly important and the demand forcomfort cooling is expanding very quickly around the world. Theincreased cooling demand results in a peak in electrical powerdemand during the hottest summer hours. This peak presents newchallenges and uncertainties to electricity utilities and theircustomers.
Cool thermal storage systems have not only the potential tobecome one of the primary solutions to the electrical powerimbalance between production and demand, but also shift coolingenergy use to off-peak periods and avoid peak demand charges.It increases the possibilities of utilizing renewable energysources and waste heat for cooling generation. In addition, acool storage can actually increase the efficiency of combinedheat and power (CHP) generation provided that heat drivencooling is coupled to CHP. Then, the cool storage may avoidpeaks in the heat demand for cooling generation, and this meansthat the CHP can operate at design conditions in most oftime.
Phase Change Materials (PCMs) used for cool storage hasobtained considerable attention, since they can be designed tomelt and freeze at a selected temperature and have shown apromising ability to reduce the size of storage systemscompared with a sensible heat storage system because they usethe latent heat of the storage medium for thermal energystorage.
The goal of this thesis is to define suitable PCM candidatesfor comfort cooling storage. The thesis work combines differentmethods to determine the thermophysical properties oftetradecane, hexadecane and their binary mixtures, anddemonstrates the potential of using these materials as PCM forcomfort cooling storage. The phase equilibrium of the binarysystem has been studied theoretically as well asexperimentally, resulting in the derivation of the phasediagram. With knowledge of the liquid-solid phase equilibriumcharacteristics and the phase diagram, an improvedunderstanding is provided for the interrelationships involvedin the phase change of the studied materials. It has beenindicated that except for the minimum-melting point mixture,all mixtures melt and freeze within a temperature range and notat a constant temperature, which is so far often assumed in PCMstorage design. In addition, the enthalpy change during thephase transition (heat of fusion) corresponds to the phasechange temperature range; thus, the storage density obtaineddepends on how large a part of the phase change temperaturerange is valid for a given application.
Differential Scanning Calorimetery (DSC) is one frequentlyused method in the development of PCMs. In this thesis, it hasbeen found that varying results are obtained depending on theDSC settings throughout the measurements. When the DSC runs ata high heating/cooling rate it will lead to erroneousinformation. Also, the correct phase transition temperaturerange cannot be obtained simply from DSC measurement. Combiningphase equilibrium considerations with DSC measurements gives areliable design method that incorporates both the heat offusion and the phase change temperature range.
The potential of PCM storage for peak shaving in differentcooling systems has been demonstrated. A Computer model hasbeen developed for rapid phase equilibrium calculation. The useof phase equilibrium data in the design of a cool storagesystem is presented as a general methodology.
Keywords:Comfort cooling, peak shaving, PCM, coolthermal storage system, DSC, phase change temperature range,the heat of fusion, phase equilibrium, phase diagram. Language:English
Wang, Shan. "Further study of the “GreenRoom” concept – an approach to sustainable datacenter cooling solution : Identification of improvement possibilities using Life Cycle Assessment (LCA) and discussion about the effect of the choice of Life Cycle Impact Assessment (LCIA) methods on the results." Thesis, KTH, Hållbar utveckling, miljövetenskap och teknik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-116474.
Повний текст джерелаThe Teliasonera Green Room Concept for high and mid density of ICT equipment
Accorinti, Flavio. "Two-Phase Power Electronics Cooling Solution Design in Air Context Answering to the Objectives of the Hybrid Aircraft 2035 High-efficiency cooling system for highly integrated power electronics for hybrid propulsion aircraft Systèmes diphasiques pour le contrôle ther- mique de l’électronique de puissance Steady-state analysis of a capillary pumped loop for terrestrial application with methanol and ethanol as working fluids Experimental and Numerical Analysis of Start-Up of a Capillary Pumped Loop for Terrestrial Applications." Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2020. http://www.theses.fr/2020ESMA0005.
Повний текст джерелаTechnological innovation and reduction of the energy required for propulsion is necessary to reduce aircrafts environmental impact. The present work is part of the research project Clean Sky 2 – HASTECS, which purpose is the development of a hybrid propulsion aircraft. The high powers involved make classical cooling solutions obsolete, in terms of efficiency, and not suitable for the power to mass ratio required for the target 2035. In particular, the problem related to power electronics cooling is assessed in this work with the purpose to achieve a performance coefficient of 25 kW/kg.This work, essentially numerical, is linked to the research, design, optimisation and analysis of a high efficiency cooling system, able to control power electronics components temperature, operating in pretty severe conditions (high thermal power density, >15kW; cyclic variation of cold source temperature and severe transient phases) and which has to be lightweight to ensure performance coefficient requirements. Different cooling technologies, active single and two-phase and passive capillary driven, have been analysed and compared on the basis of literature data and of a first approximation design: the most adapted solution has been chosen on the base of its specific power [kW/kg]. The solution that has been finally retained is a Capillary Pumped Loop for Integrated Power (CPLIP), which thermal characteristics are quite interesting and unique. After its design, the loop has been optimised to answer to objectives of 2025 and 2035. It is worth of attention the work carried out in collaboration with power electronics team of the same project to achieve a mutual optimisation of the systems. Concerning the thermal side, the attention was focused on the condenser, the heaviest component in the loop. The 2025’s solution is characterised by a classical flat plate air-methanol condenser which allowed to cross over the threshold of 15kW/kg for 2025. 2035’s solution, on the contrary, is characterised by an innovative condenser typology, using microchannels on methanol side and louvered fins on air side, allowing to obtain more than double of the power coefficient required! In this work, thermal and hydraulic characteristics of the CPLIP have been experimentally analysed, using a prototype deriving from previous studies, and by using CFD and a 0D model. Results show the ability of the CPLIP to control the temperature of power electronics modules during a short and medium-range aircraft mission profile, characterised by sudden changes of thermal load and cyclic variations of the cold source temperature.Finally, a study focused on the transient behaviour of the loop has been carried out. In particular, the start-up of the CPLIP and its behaviour during sudden and violent acceleration stages, characterising this application filed, have been exploited. In the first case, an experimental and a numerical study were carried out to demonstrate the ability of the loop to starts its operation in the most difficult thermal and environmental conditions (high thermal load and high environmental temperature). In the second case, a numerical study has been performed to understand the behaviour of the loop when an acceleration field up to 10g perturbs its operations.This work opens new interesting perspectives stand points concerning the application itself and the necessity to adopt a multidisciplinary approach to simultaneously thermally and electronically design new generation power electronics
Štaffa, Jan. "Jednofázový pulzní měnič DC/AC s digitálním řízením." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-217881.
Повний текст джерелаSchmid, Gerd, and 施高德. "Numerical and Experimental Analysis of Passive and Active Cooling Solutions for High-Power LED Light Sources." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/08213870682751115734.
Повний текст джерела國立臺灣大學
機械工程學研究所
104
Effcient thermal management is one of the most important design considerations for LED applications. This thesis presents a systematic approach to the analysis, optimization, and comparison of two thermal solutions to support high-power LED street and flood lights. Both systems, one passive and one active design, were first experimentally investigated and then numerically improved by performing large-scale parametric studies. The passive solution consists of an oversized, free-hanging rectangular heat sink with straight fins, cooled by natural convection. The main aim was to study how the inter-fin base length influences the thermal performance. A total of 55 cases were examined experimentally, and the data were used to validate the numerical model. The results show that a shorter inter-fin base length can significantly enhance thermal performance, especially when the fins are along the longer base side. For the present case, the heat transfer coefficient was increased by up to 62.7%, and the thermal resistance was reduced by 36.7% to 0.29 K/W. It was further shown that the inter-fin base length greatly influences the optimal fin spacing. In addition, Nusselt correlations including a dimensionless geometrical parameter for the inter-fin base length, which are valid for a wide range of dimensions, were developed. The active cooling system is especially designed for high-power LED street lights. It is driven by a centrifugal fan placed inside a chamber at the lower part of the lamp post. The fan is connected to the lamp head via an internal pipe to form a closed-loop forced air cooling system, where the lamp post is used for heat dissipation. The experiments were conducted using a full-scale model with an overall height of 5 m. The design includes two different heat exchangers, which were separately modeled and analyzed. The first is a vertical double pipe single-flow heat exchanger integrated into the lamp post. A 2D-axisymmetric CFD simulation with Rayleigh numbers of over 10e10 was used to investigate the heat transfer characteristics of the lamp post for various flow conditions. The second is a horizontal counter-flow heat sink inside the lamp head, which was simulated as a 3D-model using ANSYS Icepak. The effect of geometric parameters and boundary conditions, such as the inlet position, fin thickness, and fin density, were analyzed in order to optimize the thermal performance of the cooling system. It was shown that the counter-flow heat sink with a higher fin density in the middle section can reduce thermal resistance. A direct thermal comparison of both cooling systems using a 150 W COB LED revealed that the passive system can keep the excess temperature of the LED close to 40∘C at an ambient temperature of 30∘C. Under the same conditions, the active cooling system can further lower the LED temperature by 8 to 13∘C. Based on an economical comparison of both cooling systems over a period of 24 years, it was concluded that, in its present configuration, the additional costs and increased complexity of the active system outweigh the performance improvements.
ZHENG, BO-JUN, and 鄭伯俊. "Solution of 3-D cooling problem in injection molding by finite element method." Thesis, 1990. http://ndltd.ncl.edu.tw/handle/35005641466483095338.
Повний текст джерелаLian, Gou-Jaan, and 連國展. "The flow design and thermal solution of the liquid cooling system with swirl flow." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/80046900554878839808.
Повний текст джерела東南科技大學
機電整合研究所
98
This study investigates the flow field design and the thermal solution of the high power heating element by the vortex liquid cooling system. Heat was impacted directly by water liquid to go through the swirl fin of the cooling system and dissipated. The geometry parameter λ of the swirl fin is 0.00151 , 0.00436 , 0.00740 respectively, and the Reynolds number Re is the1.38 ×106, 1.85 ×106, 2.31 ×106, 2.77 ×106 respectively in the experiments of the heat flux in the range of 5.380 ~ 7.174 W/cm2. By the control parameters of different volume flow and height lift, the experiments show the best cooling effect at geometry parameter λ = 0.00151 under the condition of the same volume flow and at geometry parameter λ = 0.00436 under the condition of the same height lift. This investigation also uses the I-DEAS software to analysis the flow and thermal fields of the vortex liquid cooling system. The results compared with the practical experimental are not so significant.
Chen, Yen-lin, and 陳彥霖. "Effect of cooling rate of solution treatment on microstructure and mechanical properties of SP-700." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/58386312108010814686.
Повний текст джерела國立中央大學
材料科學與工程研究所
100
According to this research, the microstructure of solution treatment by WQ alloy of SP-700 is constructed by αp(primary α)+ α”(martensite) + βr(retained β). Stress induced martensite transformation happened during tensile process, which makes strength superior due to βr transformed into α”. WQ alloy has high strength and ductility in the meanwhile. In addition, α” and βr is going to precipitate α+β stable phase by aging treatment. Aging makes WQ alloy became much stronger but poor ductility. The microstructure of AC and FC alloys are both formed by αp+α(precipitation)+β(stable), and have better strength than WQ alloy, but there is no phase transformation during aging treatment. From the above, solution treatment and aging of WQ alloy of SP-700, which has the best strength. Good tensile properties prefer WQ alloy without aging.
Chen, Xin-Yu, and 陳欣榆. "Applying Heat Pump in Plant Factory for the Cooling of Nutrient Solution and Indoor Air." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/36216942653196960134.
Повний текст джерела國立臺灣大學
生物產業機電工程學研究所
99
Facing the global problems such as global warming, exploded population, reduction in cultivated land, food shortage, fresh water and energy crisis and food safety, plant factory is considered one of the promising methods to solve the problems, thus catching lots of attention recently. However, grow plants indoor takes lots of energy to provide light needed by the crop and to maintain proper temperature and humidity. The cost on artificial light plus the cost on air conditioning system is the major operating cost, thus reducing these light-heat related cost is the major task for the related research and successful business. This study aims at reducing air conditioning cost by applying heat pump system. The goal is to find a balance between reducing air temperature and nutrient temperature. Traditionally, only air temperature was controlled. This study tried to control the nutrient temperature and let the air temperature several degree higher and to compare the energy consumption throughout the entire growth period. Two types of heat pump cooling system were used. A-W type used a plate type exchanger to exchange energy between water in tank and refrigerant in evaporator. A-R type put the evaporator in water tank directly. No matter which type was used, the COP of the system is the major concern, if the COP is less than the commercially available Air conditioning system, there is making no sense to use it. In our experiment, the COP of A-W is much higher than A-R type. This study successfully set up a heat pump cooling system suitable or air cooling and nutrient solution cooling at the same time. A cooling system for multi-layer bench was established. The system consists of water cooled heat exchanger for each layer, fans attached to the heat-exchangers, submersible pump, nutrient tank and tap water tank which cooled with heat pump cooling system, and can be used to keep temperatures of the air within each layer and temperature of nutrient for the whole bench in different level, thus making it a flexible system for research.
Nieh, Jo-Kuang, and 聶若光. "Effect of cooling rate, plastic deformation and solution temperature on microstructure and mechanical properties of SP-700 titanium alloys." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/329qe2.
Повний текст джерела國立中央大學
機械工程學系
104
The relationship between the microstructures and the mechanical properties of solution-treated SP-700 titanium alloys, as obtained with different cooling rates, was investigated. The results indicate that the water-quenched alloy contains the primary α (αp), α”-martensite and residual β (βr) phases. Aging heat treatment can convert both α”-martensite and the βr phases to the fine-grained α + β equilibrium phases, resulting in a significant increase in tensile strength and hardness. Both the air-cooled and furnace-cooled alloys consist of the αp, α and β phases. The air-cooled alloy containing the fine-grained α phase has relatively higher hardness. Aging heat treatment causes only a slight enhancement in tensile properties because it cannot convert the phases in both alloys. Stress-induced martensitic phase transformation occurs in the water-quenched alloy under applied stress, after which the alloy exhibits higher tensile strength, higher ductility, and lower yield strength. This study investigates the effects of cold working prior to aging on the microstructure and mechanical properties of SP-700 titanium alloy. The results indicate that the microstructure of the quenched alloy comprises blocky primary α, retained β, and acicular α” martensite distributed in the β matrix. The retained β is transformed to denser and finer brittle acicular martensite α” by stress-induced martensitic transformation and the quantity of retained β decreases with higher degrees of cold working. The quenched alloy exhibits not only low yield strength, but the stress-induced martensite leads to a distinct increase in strength with good ductility. Plastic deformation prior to the aging treatment produces a great increase in the yield strength due to refinement of the precipitate microstructure, leading to the ratio of strength increment and ductility being very low.
Chiou, Mau-Sheng, and 邱茂盛. "Study of Aluminum Element and Solution Heat Treatment Cooling Rate on High-Temperature Creep and Oxidation Behavior of Directionally Solidified CM-247LC Ni-based Superalloy." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/a79zc6.
Повний текст джерела義守大學
材料科學與工程學系
103
In this study, CM-247LC nickel-based superalloy was selected as a base material for alloy design, by revising heat treatment process and changing element content, to explore the effects of high temperature creep behavior and high temperature oxidation properties. The results showed that adding 1 wt.% Al element in CM-247LC nickel-based superalloy could promote gamma prime phase precipitation, improve volume fraction, enhance its high temperature creep properties, increase the Al activity, stimulate Al2O3 oxide layer at high temperatures, and advance oxidation resistance. When cooling rate after solution treatment is slower, gamma prime phase becomes thicker; consequently the high temperature creep properties are reduced. In the high temperature and ultra-high temperature creep testing, gamma prime phase was transformed into rafting structure to resist dislocation movement, but diffusion behavior is the main mechanism in the ultra-high temperature. Rafting structure was not produced in intermediate temperature; however the main deformation mechanism is dislocation movement.
Chang, Chin-Wei, and 張晉瑋. "Using thermochromic liquid crystal slurries to investigate the effect of a slanted cooling wall on the development of double-diffusive convection during the solidification of a liquid super-eutectic binary solution." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/6rh494.
Повний текст джерела國立臺北科技大學
能源與冷凍空調工程系碩士班
100
Solidification of liquid binary alloys is found in various industrial applications, such as marine science, silicon crystal growth process, the ice storage system in HVAC, the food processing and cold storage in food industry, the metal alloys casting and low-temperature biotechnology applications. The natural convection phenomenon, also known as double-diffusive convection, which occurs during the solidification process owing to the effects of temperature and concentration gradients, is likely to cause poor quality of alloy castings. The factors contributing to the formation of double-diffusive convection and the means to eliminate or weaken such phenomenon have been the focus of research in the past. This study focused on the effect of slanted lateral cooling wall with negative slope on the formation of double-diffusive convection during the solidification of a 25 wt. % hyper-eutectic binary solution (NH4CL-H2O). Particle Image Velocimetry (PIV) techniques, thermochromic liquid crystal (TLC) and Schlieren method were employed to observe the flow development of the binary solution in the liquid. The experimental results showed that the water-rich fluid was continuously released through the mushy layer during solidification, resulting in the formation of a red color layer on the thermochromic liquid crystal. The image processing software was used for temperature field visualization. The experimental results also indicated that the lateral cooling wall with different slope has significant effects on the formation of double-diffusive convection during solidification. The growth process of double-diffusive convection varies apparently between the lateral cooling walls with higher slopes, such as in the case of 0 and 5 degrees compared to those with lower slopes, such as in the case of 10 and 15 degrees. As the slope of lateral cooling wall decreases, the filling-box process becomes faster and the time for the flow development to reach steady state becomes shorter.
CHANG, CHIA-HSING, and 張家馨. "(I)Synergistic Effect of Dynamic-cooling/Freeze-drying Process and Fullerene Bisadduct on the Morphology of Conjugated Polymer/PCBM Blends(II)Shear-induced Crystallization Process of pBCN/PCBM in o-xylene Solution." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/7d946x.
Повний текст джерела輔仁大學
化學系
107
P3HT/PCBM blend films have been used in the photoactive layer of polymer solar cells. In the blend film, bulk-heterojuction (BHJ) structure can enhance contact area between materials and facilitate the exciton dissociation. In addition, controlling molecular aggregation of conjugating polymer has been a critical issue for polymer solar cells. Higher crystalline of P3HT is benificial to absorption spectra and carrier mobility. Thermal annealing has been used to improve crystalline of P3HT in many references. However, thermal annealing results in phase separation due to poor compatibility. Here, the new processes are applied to improve crystalline of polymer prior to coating process and decrease probability of phase separation so that minimum/or no post-treatment .With respect to materials, in high PCE polymer solar cells, low band-gap conjugated copolymer has been widely used to enhance absorption spectra recently, however, they are not often crystallizable because of different monomers used in the polymer backbones. Therefore, this study will apply the new processes to conjugated copolymer (pBCN). Part one, synergistic effect of dynamic cooling/freeze drying process is applied to pBCN/PCBM blend to enhance aggregation of pBCN and decrease agglomeration of PCBM. The dynamic-cooling process allows pBCN molecules to aggregate in solution into a more organized structure during the cooling process; the freeze-drying process prevents severe agglomeration of PCBM during the solvent removing process. To improve stability of blend films, we add additive (bis-PCBM) to decrease agglomeration of PCBM after thermal annealing. Part two, a shear–induced-crystallization (SIC) process is applied to the polymer solution prior to coating process. Experimental results indicate that after applying SIC process to a crystallizable polymer, pBCN, aggregation of pBCN is enhanced than that from spin-coating process. Additionally, film absorption study shows that aggregation of pBCN does not affected by addition of PCBM, which makes the SIC process feasible for the fabrication of polymer solar cells.