Pulse tube cryocoolers (PTCs) are among the most attractive choices of refrigerators for applications requiring up to 1 kW of cooling in the temperature range of 4-123 K as a result of the high relative efficiency of the Stirling cycle, the reliability of linear compressors, and the lack of cryogenic moving parts resulting in long life and low vibration signature. Recently, PTCs have been successfully used in applications in the 150 K range, extending the useful range of the device beyond the traditional cryogenic regime. A carefully designed cylindrical cavity referred to as the pulse tube replaces the mechanical expander piston found in a Stirling machine. A network consisting of the pulse tube, inertance tube, and surge volume invoke out-of-phase pressure and mass flow oscillations while eliminating all moving parts in the cold region of the device, significantly improving reliability over Stirling cryocoolers. Terrestrial applications of PTCs expose a fundamental flaw. Many PTCs only function properly in a narrow range of orientations, with the cold end of the pulse tube pointed downward with respect to gravity. Unfavorable orientation of the cold head often leads to a catastrophic loss of cooling, rendering the entire cryocooler system inoperable. Previous research indicates that cooling loss is most likely attributed to secondary flow patterns in the pulse tube caused by free convection. Convective instability is initiated as a result of non-uniform density gradients within the pulse tube. The ensuing secondary flow mixes the cryogen and causes enhanced thermal transport between the warm and cold heat exchangers of the cryocooler. This study investigates the nonlinear stabilizing effect of fluid oscillation on Rayleigh-Bénard instability in a cryogenic gas subject to misalignment between gravitational body force and the primary flow direction. The results are directly applicable to the flow conditions frequently experienced in PTCs. Research has shown that the convective component can be minimized by parametrically driven fluid oscillation as a result of sinusoidal pressure excitation; however, a reliable method of predicting the influence of operating parameters has not been reported. In this dissertation, the entire PTC domain is first fully simulated in three dimensions at various angles of inclination using a hybrid method of finite volume and finite element techniques in order to incorporate conjugate heat transfer between fluid domains and their solid containment structures. The results of this method identify the pulse tube as the sole contributor to convective instability, and also illustrate the importance of pulse tube design by incorporating a comparison between two pulse tubes with constant volume but varying aspect ratio. A reduced domain that isolates the pulse tube and its adjacent components is then developed and simulated to improve computational efficiency, facilitating the model’s use for parametric study of the driving variables. A parametric computational study is then carried out and analyzed for pulse tubes with cold end temperatures ranging from 4 K to 80 K, frequencies between 25-60 Hz, mass flow - pressure phase relationships of -30◦ and +30◦, and Stokes thickness-based Reynolds numbers in the range of 43-350, where the turbulent transition occurs at 500. In order to validate the computational models reported and therefore justify their suitability to perform parametric exploration, the CFD codes are applied to a commercially developed single stage PTR design. The results of the CFD model are compared to laboratory-measured values of refrigeration power at temperatures ranging from 60 K to 120 K at inclination angles of 0◦ and 91◦. The modeled results are shown to agree with experimental values with less than 8.5% error for simulation times of approximately six days using high performance computing (HPC) resources through Georgia Tech’s Partnership for Advanced Computing (PACE) cluster resource, and 10 days on a common quad-core desktop computer. The results of the computational parametric study as well as the commercial cryocooler data sets are compiled in a common analysis of the body of data as a whole. The results are compared to the current leading pulse tube convective stability model to improve the reliability of the predictions and bracket the range of losses expected as a function of pulse tube convection number. Results can be used to bracket the normalized cooling loss as a function of the pulse tube convection number NPTC. Experimental data and simulated results indicate that a value of NPTC greater than 10 will yield a loss no greater than 10% of the net pulse tube energy flow at any angle. A value of NPTC greater than 40 is shown to yield a loss no greater than 1% of the net pulse tube energy flow at all angles investigated. The computational and experimental study completed in this dissertation addresses static angles of inclination. Recent interest in the application of PTCs to mobile terrestrial platforms such as ships, aircraft, and military vehicles introduces a separate regime wherein the angle of inclination is dynamically varying. To address this research need, the development of a single axis rotating cryogenic vacuum facility is documented. A separate effects apparatus with interchangeable pulse tube components has also been built in a modular fashion to accommodate future research needs.

Atualmente, a análise de desempenho de sistemas de refrigeração domésticos é realizada através de ensaios experimentais normalizados. Durante esses experimentos, diversas variáveis como pressões de trabalho, temperaturas em diversos pontos do sistema, corrente elétrica e potência consumida, são monitoradas. Porém, em muitos casos são necessárias mais de 24 horas para execução de um teste experimental (e.g., teste abaixamento de temperatura). Tendo em vista o tempo despendido nestes testes, propõe-se no presente trabalho um modelo matemático semi-empírico capaz de predizer o comportamento das variáveis do sistema testado e, com isso, antecipar o final do ensaio. O modelo, desenvolvido através das leis de conservação da massa e da energia, apresenta parâmetros que são ajustados a partir de informações experimentais obtidas durante a execução do próprio teste. Após a inicialização do ensaio, a cada período de tempo prédeterminado, os dados medidos são utilizados para determinar os parâmetros empíricos do modelo. Obtidas as constantes, simula-se o comportamento das principais variáveis do sistema de refrigeração até a condição de regime permanente. Com isso, o teste experimental pode ser finalizado com antecedência. O modelo desenvolvido é capaz de prever com boa precisão, a partir de duas horas de teste, a variação da vazão mássica e da pressão de sucção (com diferenças da ordem de 10% em regime permanente quando comparadas às variáveis experimentais), da pressão de condensação (com diferença da ordem de 5%) e da temperatura da parede do condensador (diferença da ordem de 2°C). / The performance of household refrigeration systems are usually evaluated through experimental tests carried at in temperature and humidity controlled chambers. During the tests, the discharge and suction pressures, the temperature in several system positions, and the compressor power are measured. These tests are expensive and time-demanding, e.g., a single pull-down test can take more than 24 hours to be performed. Although the mathematical models have been proposed for decades as an alternative to the experiments, they are not sufficiently reliable to substitute completely the tests. Therefore, the current work proposes a semiempirical mathematical model to predict the system performance with the purpose of reducing the test time instead of replacing it. The model is based on the mass and energy conservation equations in which the constant parameters, such as conductance and capacitances, are calibrated from previous measured values of temperature and pressure. As soon as the parameters are obtained, a simulation is performed to forecast future values of temperature, pressure and compressor power and therefore, to anticipate the end of the test. Calibrations and simulations can be continuously performed as the test evolves. Preliminary results show that steadystate values of discharge and suction pressures can be predicted within error bands of 5 and 10%, respectively, after only two hours of a pull-down test being performed.

Made available in DSpace on 2016-12-08T17:19:33Z (GMT). No. of bitstreams: 1 Resumo - Claudemir carvalho.pdf: 30337 bytes, checksum: cec0b031ed734679cb6e0604a451360f (MD5) Previous issue date: 2009-05-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this study, the primary recycling of ABS Poli(acrilonitrile butadiene styrene) inside the industry was the main subject of the analyses. Many studies have been running on recycling of end life cycle of manufactured products, however a source of rejects inside the industry can be explored and be used to reduce costs and optimize expensive raw materials. Each kilogram of rejects inside the productive cycle that is recycled for the same part that was destined, represents a economy for the company and a benefit to the environment too. The ABS as commodity has been target of a lot of studies how much to its performance in the product and also how much to the recycling of rejects from the end of life cycle products as lower requests products. In fact, the present study has as the material object a specific grade of ABS used in the industry of refrigerators. Has also the objective to evaluate the behavior of the virgin ABS with ABS scrap and to reintroduce it in the productive process for the same application that was destined. It was evaluated the chemical, mechanical, rheological and thermal properties of mixtures of the virgin ABS with scrap in five different concentrations. This ABS is used for injection process and the material scrap was carefully gotten and mixed mechanically to the virgin ABS. The samples had been characterized by Fourier transform infra-red (FTIR), differential scanning calorimetry (DSC), mechanical tensile testing, thermogravimetric analyses (TGA) and rheometry. The values of elasticity modulus (E), maximum tensile and elongation at break remained steady with the addition of scrap. The viscosity of the ABS measured by capillary rheomether reduced with the addition of scrap, accordingly with the increase of shear rate and temperature. From the results of flow index obtained with the Plastometer it was possible to determine the end correction of Bagley (e). Using this correction it was possible to correct the viscosity curves, however it was not possible to define a commom index for the hole temperatures. The FTIR spectra had not indicated significant changes in the concentration of the characteristic components, only to styrene in most than 20% scrap, as well as had not pointed out the starting of degradation. The glass transition temperature presented a reduction with the addition of scrap and the starting loss of mass temperature remained steady with the addition of scrap. / A reciclagem primária do ABS Poli(acrilonitrila butadieno estireno) para fins de incorporação dos rejeitos dentro do processo produtivo foi o tema principal desse trabalho. Muito se têm pesquisado sobre reciclagem de rejeitos oriundos do final do ciclo de vida de um produto manufaturado, no entanto existe uma fonte de resíduos poliméricos originados dentro da própria indústria que pode ser explorada e aproveitada como fonte de redução de custos e reutilização de matérias-primas nobres. Cada quilo de material rejeitado dentro do ciclo produtivo que é reaproveitado para o mesmo fim que foi previamente destinado, representa uma economia financeira para essa empresa e um benefício ao meio ambiente. O ABS como commodity tem sido alvo de inúmeras pesquisas quanto ao seu desempenho no produto acabado e também quanto à reintrodução de resíduos do final de ciclo de vida como artefatos de menor valor agregado. Enfim, o presente trabalho tem como material um grade de ABS específico utilizado na indústria de refrigeradores e tem como objetivo avaliar o comportamento desse ABS virgem com refugo do mesmo material para fins de reintrodução no processo produtivo para a mesma aplicação que foi destinado inicialmente. Foram avaliados o comportamento químico, mecânico, reológico e térmico de misturas do ABS virgem com refugo em seis proporções diferentes. Esse ABS é destinado para injeção sob pressão e o refugo foi cuidadosamente obtido e misturado mecanicamente ao ABS virgem. As amostras foram caracterizadas por espectroscopia no infravermelho com transformada de Fourier (FTIR), calorimetria exploratória diferencial (DSC), termogravimetria (TG), ensaios mecânicos de tração e reometria capilar. Os valores de módulo de elasticidade (E), tensão máxima e alongamento na ruptura mantiveram-se estáveis com a adição de refugo. A viscosidade do ABS medida no reômetro capilar reduziu com a adição de refugo, acentuando-se com o aumento da taxa de cisalhamento e temperatura. A partir dos resultados de índice de fluidez obtidos com o Plastômetro foi possível determinar o índice de correção de Bagley (e) em relação à viscosidade do reômetro capilar. Utilizando-se este índice foi possível corrigir as curvas de viscosidade determinadas por meio do Plastômetro, no entanto não foi possível definir um índice de correção comum para todas as temperaturas. Os espectros de FTIR não indicaram alterações significativas das ligações características dos componentes do ABS, apenas uma pequena redução das ligações de estireno para as misturas com mais de 20% e não indicaram o surgimento de produtos de degradação. A temperatura de transição vítrea apresentou uma ligeira redução com o incremento da quantidade de refugo, e a temperatura de início de perda de massa manteve-se estável em todas as misturas.

Made available in DSpace on 2017-07-10T17:44:30Z (GMT). No. of bitstreams: 1 2014_Antonio_Carlos_Chidichima.pdf: 1245017 bytes, checksum: 3396ea2d486c08827f4e7169d0250dce (MD5) Previous issue date: 2014-08-22 / The fish industrialization is a sector of the economy which is growing in Brazil and world wide, supported by consumption increase and encouraged by the high quality that the product provides. Brazil has huge potential for the fish production in excavated tank and in cages, whereas the western Paraná and Baixo Iguaçu, located on the left bank of the Hydropower Plant Reservoir Governor Jose Richa, have great features for fishing activity. In this region, the fish slaughtering and industrialization has great importance in business scenario, meets the demand generated by consumers and moves the agrifood chain of family agriculture, including. This study aims to identify what are the prospects and challenges for the sector and analyze the inserted technology and efficiency in the procedures, methods and recovery of waste generated in the industrialization of tilapia fillet, for use in the manufacture of new products. The research is a case study and was conducted with the managers of 17 fridges in the region. Applied in the form of qualitative and quantitative interviews with semi-structured questionnaire and a specific software IBM SPSS, was used to analyze the results. The fridges are certified in four categories of official sanitary inspection for commercialization of the fisheries, and were separated by group certification for data analysis. It was concluded that there are significant difficulties with the shortage of labor and high employee turnover. Prospects are promising for the development, growth, and increase of slaughter capacity of fridges. It is an emerging chain, with newer facilities fridges with SIM / POA, important in the generation of familiar income, with intensive use of labor, low technology in automation and new products and great dependence on a single product / A industrialização de pescados é um setor da economia que está em crescimento no Brasil e no mundo, apoiado pelo crescimento do consumo e incentivado pela alta qualidade que o produto oferece. O Brasil possui enorme potencial para produção de peixes em tanque escavado e em tanques redes, sendo que as regiões oeste do Paraná e as regiões do Baixo Iguaçu, localizadas na margem esquerda do reservatório da Usina Hidrelétrica Governador Jose Richa, possuem ótimas características para a atividade pesqueira. Nesta região, o abate e industrialização de peixes têm grande importância no cenário comercial, atendem à demanda gerada pelos consumidores e movimentam inclusive a cadeia agroalimentar da agricultura familiar. Este estudo tem por objetivo identificar quais são as perspectivas e desafios para o setor, analisar a tecnologia inserida e a eficiência nos procedimentos, métodos e aproveitamento de resíduos gerados na industrialização do filé de tilápia para aproveitamento na fabricação de novos produtos. A pesquisa é um estudo de caso e foi realizada junto aos gestores de 17 frigoríficos da região. Aplicada em forma de entrevista qualitativa e quantitativa, com questionário semiestruturado e foi utilizado software específico IBM SPSS para a análise dos resultados. Os frigoríficos estão certificados em quatro categorias de inspeção sanitária oficial para comercialização do pescado e foram separados por grupo de certificação para a análise dos dados. Foi possível concluir que existem grandes dificuldades, como a falta de mão de obra e a alta rotatividade dos funcionários. As perspectivas são promissoras ao desenvolvimento, ao crescimento, e ao aumento da capacidade de abate dos frigoríficos. É uma cadeia emergente, com as instalações mais recentes sendo as dos frigoríficos com certificação SIM/POA, importantes para a geração de renda familiar, com uso intensivo de mão de obra, pouca tecnologia em automação e novos produtos e grande dependência de um único produto

Магистерская диссертация посвящена разработке программного обеспечения интеллектуальной системы анализа температуры холодильников системы охлаждения доменной печи. В ходе работы рассмотрены основные этапы реализации программного модуля: анализ предметной области, функциональное моделирование, проектирование и программная реализация web-приложения. Разработанная система предоставляет пользователю возможность отображения данных о температуре в графическом и табличном виде, а также проведение анализа и прогнозирования температуры тела холодильника в доменной печи. Она позволяет оперативно мониторить и контролировать температурные показатели, что является важным фактором для обеспечения эффективности и надежности работы печи. Научная новизна полученных в работе результатов заключается в разработке методов эффективной организации, ведения процесса разработки и сопровождения специализированного информационного, алгоритмического и программного обеспечения, включая базу данных доменного цеха и пользовательское приложение системы интеллектуального анализа температуры холодильников системы охлаждения доменной печи: использование гибкой методологии разработки (Agile, SCRUM) и таск-трекера Microsoft Azure DevOps для ведения проекта, взаимодействия с заказчиком во время разработки, отслеживания ошибок, визуального отображения задач и мониторинга процесса их выполнения; функциональное моделирование процессов и подсистем для реализации web-приложения подготовки технического отчета доменного цеха на основе методологии IDEF0 и средства реализации Ramus Educational; использование методики коллективного владения программным кодом на основе сервиса (удаленного репозитория) GitHub; применение методов машинного обучения для реализации алгоритма прогнозирования температуры холодильников системы охлаждения доменной печи. Практическая значимость результатов заключается в том, что разработанное программное обеспечение позволит: программное обеспечение позволит сэкономить время на получение, хранение, обработку данных, что положительно скажется на эффективности работы доменного производства, поможет снизить риск возникновения аварийных ситуаций и неплановых остановок доменных печей; специалистам отдела сопровождения информационных систем снизить трудозатраты на сопровождение, совершенствование и развитие системы с учетом пожеланий пользователей. Результаты работы могут быть использованы также в учебном процессе для обучения бакалавров и магистрантов по направлению «Информационные системы и технологии». Результаты работы представлены и обсуждены на международных и всероссийских конференциях: X, XI Всероссийских научно-практических конференциях студентов, аспирантов и молодых учёных «Теплотехника и информатика в образовании, науке и производстве» (ТИМ’2022, ТИМ’2023) с международным участием (г. Екатеринбург, УрФУ, 2022, 2023); Всероссийской научно-практической конференции (с международным участием) «Системы автоматизации (в образовании, науке и производстве)» AS’2022 (г. Новокузнецк, СибГИУ, 2022); международной научно-технической конференции «Состояние и перспективы развития электро и теплотехнологии» XXII Бенардосовские чтения (г. Иваново, ИГЭУ, 2023). / The master's thesis is devoted to the development of software for an intelligent system for analyzing the temperature of refrigerators in the blast furnace cooling system. In the course of the work, the main stages of the implementation of the software module were considered: domain analysis, functional modeling, design and software implementation of a web application. The developed system provides the user with the ability to display temperature data in graphical and tabular form, as well as to analyze and predict the body temperature of the refrigerator in the blast furnace. It allows you to quickly monitor and control temperature indicators, which is an important factor for ensuring the efficiency and reliability of the furnace. The scientific novelty of the results obtained in the work lies in the development of methods for the effective organization, management of the development process and maintenance of specialized information, algorithmic and software, including the database of the blast furnace shop and the user application of the system for intelligent temperature analysis of the refrigerators of the blast furnace cooling system: − use of flexible development methodology (Agile, SCRUM) and the Microsoft Azure DevOps task tracker for project management, interaction with the customer during development, tracking errors, visual display of tasks and monitoring the progress of their implementation; − functional modeling of processes and subsystems for the implementation of a web application for preparing a technical report for a blast furnace shop based on the IDEF0 methodology and the Ramus Educational implementation tool; − use of the methodology of collective ownership of program code based on the service (remote repository) GitHub; − application of machine learning methods to implement an algorithm for predicting the temperature of refrigerators in the blast furnace cooling system. The practical significance of the results lies in the fact that the developed software will allow: − the software will save time for receiving, storing, processing data, which will have a positive impact on the efficiency of blast-furnace production, help reduce the risk of emergencies and unscheduled shutdowns of blast furnaces; - specialists of the information systems maintenance department to reduce labor costs for maintenance, improvement and development of the system, taking into account the wishes of users. The results of the work can also be used in the educational process for training bachelors and masters in the direction of "Information Systems and Technologies". The results of the work are presented and discussed at international and all-Russian conferences: X, XI All-Russian scientific and practical conferences of students, graduate students and young scientists "Heat engineering and informatics in education, science and production" (TIM'2022, TIM'2023) with international participation (Ekaterinburg, UrFU, 2022, 2023); All-Russian scientific and practical conference (with international participation) "Automation systems (in education, science and production)" AS'2022 (Novokuznetsk, SibGIU, 2022); International Scientific and Technical Conference "Status and Prospects for the Development of Electrical and Thermal Technologies" XXII Benardos Readings (Ivanovo, ISPU, 2023).