Orientador: José Luiz Gasche / Resumo: Compressores herméticos alternativos são amplamente utilizados em sistemas de refrigeração por compressão de vapor de pequeno e médio porte. O sistema de válvulas automáticas utilizadas para controlar os processos de sucção e descarga é um componente importante deste tipo de compressor. O estudo experimental ou analítico/numérico destes processos é bastante complexo devido, principalmente, à interação fluido-estrutura entre as válvulas e o escoamento de fluido refrigerante. Uma revisão de literatura mostra que este tema ainda merece muita atenção dos pesquisadores, em particular daqueles que necessitam de dados experimentais acurados para validação de metodologias numéricas. Este é o contexto deste trabalho, cujo objetivo é descrever a dinâmica do movimento de um modelo de válvula usada neste tipo de compressor. Sensores óticos foram utilizados para medir o deslocamento instantâneo de modelos de válvulas fabricadas em aço mola SAE 1070 com 0,4 e 0,5 mm de espessura. Os testes foram realizados para escoamentos com números de Reynolds variando de 1.500 a 19.000. A descrição da dinâmica da válvula foi apresentada pela sua amplitude, frequência, pressão máxima à montante do escoamento da válvula e pelo coeficiente de restituição no impacto entre a válvula e o assento. De uma maneira geral, identificamos que a dinâmica da válvula depende significativamente de sua rigidez, do valor de força de pré-carga que está sujeita e do número de Reynolds do escoamento que incide sobre sua sup... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Hermetic reciprocating compressors are widely used in small and medium size vapor compression refrigeration systems. An important component of this type of compressor is the automatic valve system used for controlling the suction and discharge processes. The experimental or analytical/numerical study of this system is complex due to the fluid-structure interaction between the valves and the refrigerant flow. A literature review suggests that this theme still deserves attention from the researchers, in particular for those who need accurate experimental data to validate numerical methodologies. We aim to describe the dynamics of a suction valve model used in this type of compressor. Optical sensors were used to measure the instantaneous displacement of a spring-steel SAE 1070 valve model with 0.4 and 0.5 mm thickness. The tests were performed for Reynolds number of the flow ranging from 1,500 to 19,000. We present the dynamic behavior of the valve by its amplitude, frequency, maximum upstream pressure of the valve, and coefficient of restitution of the impact between valve and seat. Generally, we identify that the valve dynamics depends significantly on its stiffness, precharging force and Reynolds numbers of the flow. The impact between valve and seat also significantly change the dynamics of the movement. / Mestre

O presente trabalho realiza o estudo e aplicação de um algoritmo de branch-and-price para a resolução de um problema de escalonamento de compressores. O problema é ligado à produção petrolífera, o qual consiste em definir um conjunto de compressores a serem ativados para fornecer gas de elevação a um conjunto de poços, atendendo toda demanda e minimizando os custos envolvidos. O problema é caracterizado por uma função objetivo não-convexa que é linearizada por partes de forma a ser formulada como um problema de programação inteira mista. A abordagem de geração de colunas é baseada na decomposição de Dantzig-Wolfe e apresenta melhores limitantes inferiores em relação à relaxação linear da formulação compacta. O branch-and-price é comparado ao solver CPLEX, sendo capaz de encontrar a solução ótima em menor tempo para um conjunto de instâncias, bem como melhores soluções factíveis para instâncias maiores em um período de tempo limitado. / This work presents the study and application of a branch-and-price algorithm for solving a compressor scheduling problem. The problem is related to oil production and consists of defining a set of compressors to be activated, supplying the gas-lift demand of a set of wells and minimizing the associated costs. The problem has a non-convex objective function, to which a piecewise-linear formulation has been proposed. This dissertation proposes a column generation approach based on the Dantzig-Wolfe decomposition, which achieves tighter lower bounds than the straightforward linear relaxation of the piecewise-linear formulation. The column generation was embedded in a branch-and-price algorithm and further compared with CPLEX, obtaining optimal solutions in lesser time for a set of instances. Further, the branch-and-price algorithm can find better feasible solutions for large instances under a limited processing time.

Le présent travail s'inscrit dans le cadre d'une convention CIFRE entre Liebherr-Aerospace Toulouse SAS et le Département d'Aérodynamique Energétique et Propulsion (DAEP) de l'ISAE. L’étude porte sur l'analyse des mécanismes responsables de la perte de la stabilité d'un étage de compression centrifuge. L'objectif industriel sous-jacent est l'élargissement de la plage de fonctionnement stable des compresseurs. Les travaux sont abordés par voie numérique à l'aide du code de calcul elsA, développé par l'ONERA et le CERFACS. Les simulations instationnaires sont effectuées sur la circonférence complète des roues.La topologie de l'écoulement est analysée dans un premier temps selon trois points de fonctionnement stables répartis sur la courbe caractéristique de l'iso-vitesse de design. Cette analyse permet de décrire l'évolution des phénomènes lorsque le débit est réduit. Au voisinage de la ligne de stabilité, l'excès d'incidence sur les aubes du rouet déclenche le décollement de la couche limite sur la face en d’expression. Le guide issu de la zone décollée migre en direction du carter et alimente l'écoulement de jeu. En conséquence, le déficit de vitesse au voisinage du carter s'intensifie et un lâcher périodique de structures tourbillonnaires apparaît à l'interface entre les écoulements secondaires et l'écoulement principal.La perte de la stabilité de l'étage s’établit suite à la naissance d'une perturbation de type « modal » au sein de l'espace lisse. Cette dernière induit de fortes distorsions circonférentielles dans l'étage de compression mais affecte plus particulièrement l'écoulement à l'entrée du rouet. Sur la moitié de la circonférence, l'interface entre les écoulements secondaires et l'écoulement principal ainsi que les structures tourbillonnaires sont déplacées en amont du front de grille. Le taux total-total du rouet chute de manière brutale et entraîne la perte de la stabilité de l'étage.Enfin, la dernière partie de ce travail est dédiée à la mise en place de critères adaptés au modèle stationnaire mono-canal utilisé chez LTS. Ces critères seront utilisés pour améliorer la prédiction de la ligne de pompage en phase de design. Dans un premier temps, la pertinence de l'utilisation du modèle stationnaire au voisinage de la ligne de stabilité est évaluée. Dans un second temps, les influences de la vitesse de rotation et de la géométrie de l’étage sur la topologie sont étudiées.Deux situations sont jugées critiques vis-à-vis de la stabilité. La première concerne l'alignement de l'interface entre l'écoulement de jeu et l'écoulement principal avec le front de grille. La deuxième concerne l'opération du compresseur avec un angle d'écoulement en sur-incidence sur les aubes du diffuseur qui s'établit sur toute la hauteur de veine. / This work results from a CIFRE partnership between Liebherr-Aerospace Toulouse SAS and the Aerodynamics, Energetics and Propulsion Department (DAEP) of ISAE. The main objective is to investigate the mechanisms responsible of the stall onset in a centrifugal compressor operating at the nominal rotational speed. It is part of a larger work which aims at extending the stable operating range of compressors integrated in air conditioning system. The analyses are based on the results of unsteady simulations, in a calculation domain comprising all the blade passages. They are performed with the elsA software developed by ONERA and CERFACS.The investigations show the modifications of the unsteady flow pattern when the mass flow is reduced along the speed line. Near the stability limit, the high incidence angle on the impeller blade leads to a boundary layer separation on the suction side. The fluid in the separation zone moves toward the shroud and enlarges the low momentum flow zone generated by the leakage flow. The interface between the leakage flow and the main flow becomes unstable to the extent of a periodic vortex formation.The path to instability is driven by the growth of a small amplitude disturbance (modal wave) rotating in the vaneless space. The length scale of the wave is equal to the compressor circumference. This perturbation induces distortions and alters the flow characteristics in every location of this subsonic stage, and more specifically the impeller inlet flow structure: the unstable interface between the main flow and the leakage flow is periodically moved upstream of the leading edge plane causing a significant drop of the impeller total-to-total pressure ratio. The last part of this work concerns the definition of criteria which can improve the surge line prediction during the design process in an industrial environment. Therefore, they are adapted to the numerical steady model using the mixing plane approach. To do so, the capacity of the steady model to predict the flow structure when the compressor operates near stall is investigated. Then, the effects of the rotational speed and of the compressor geometry are evaluated. Theses two steps have permitted to define two critical situations regarding the stage stability. The first one is related to the alignment of the interface between the main flow and the leakage flow with the leading edge plane. The second one concerns the compressor operation with positive incidence on the diffuser vane, along the full span.

Submitted by Gabriel Biancolin Moimas (gabrielmoimas18@gmail.com) on 2018-06-18T11:47:19Z No. of bitstreams: 1 Dissertação.pdf: 13607292 bytes, checksum: 4574d9cd3135ad2562a9648fd1641465 (MD5) / Approved for entry into archive by Cristina Alexandra de Godoy null (cristina@adm.feis.unesp.br) on 2018-06-18T12:12:00Z (GMT) No. of bitstreams: 1 moimás_gb_me_ilha.pdf: 13607292 bytes, checksum: 4574d9cd3135ad2562a9648fd1641465 (MD5) / Made available in DSpace on 2018-06-18T12:12:00Z (GMT). No. of bitstreams: 1 moimás_gb_me_ilha.pdf: 13607292 bytes, checksum: 4574d9cd3135ad2562a9648fd1641465 (MD5) Previous issue date: 2018-05-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Compressores herméticos alternativos são amplamente utilizados em sistemas de refrigeração por compressão de vapor de pequeno e médio porte. O sistema de válvulas automáticas utilizadas para controlar os processos de sucção e descarga é um componente importante deste tipo de compressor. O estudo experimental ou analítico/numérico destes processos é bastante complexo devido, principalmente, à interação fluido-estrutura entre as válvulas e o escoamento de fluido refrigerante. Uma revisão de literatura mostra que este tema ainda merece muita atenção dos pesquisadores, em particular daqueles que necessitam de dados experimentais acurados para validação de metodologias numéricas. Este é o contexto deste trabalho, cujo objetivo é descrever a dinâmica do movimento de um modelo de válvula usada neste tipo de compressor. Sensores óticos foram utilizados para medir o deslocamento instantâneo de modelos de válvulas fabricadas em aço mola SAE 1070 com 0,4 e 0,5 mm de espessura. Os testes foram realizados para escoamentos com números de Reynolds variando de 1.500 a 19.000. A descrição da dinâmica da válvula foi apresentada pela sua amplitude, frequência, pressão máxima à montante do escoamento da válvula e pelo coeficiente de restituição no impacto entre a válvula e o assento. De uma maneira geral, identificamos que a dinâmica da válvula depende significativamente de sua rigidez, do valor de força de pré-carga que está sujeita e do número de Reynolds do escoamento que incide sobre sua superfície. O impacto entre válvula e assento também altera significativamente a dinâmica do movimento. / Hermetic reciprocating compressors are widely used in small and medium size vapor compression refrigeration systems. An important component of this type of compressor is the automatic valve system used for controlling the suction and discharge processes. The experimental or analytical/numerical study of this system is complex due to the fluid-structure interaction between the valves and the refrigerant flow. A literature review suggests that this theme still deserves attention from the researchers, in particular for those who need accurate experimental data to validate numerical methodologies. We aim to describe the dynamics of a suction valve model used in this type of compressor. Optical sensors were used to measure the instantaneous displacement of a spring-steel SAE 1070 valve model with 0.4 and 0.5 mm thickness. The tests were performed for Reynolds number of the flow ranging from 1,500 to 19,000. We present the dynamic behavior of the valve by its amplitude, frequency, maximum upstream pressure of the valve, and coefficient of restitution of the impact between valve and seat. Generally, we identify that the valve dynamics depends significantly on its stiffness, precharging force and Reynolds numbers of the flow. The impact between valve and seat also significantly change the dynamics of the movement.

Made available in DSpace on 2016-12-12T17:38:34Z (GMT). No. of bitstreams: 1 Resumo e Abstract - Marcelo Zanelato.pdf: 40596 bytes, checksum: dde8f1ed9fc529913a1ef11f5663efd9 (MD5) Previous issue date: 2015-07-03 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neste trabalho é realiza do um estudo da aplicação do circuito gradador de tensão em compressores herméticos para refrigeração doméstica. Os motores de indução operam com fluxo de entreferro quase constante, o que significa perdas magnéticas também quase constantes. A variação da tensão aplicada ao motor com consequente redução do fluxo no entre ferro representa um ganho de eficiência em relação à alimentação com tensão nominal fixa, quando a carga não requer fluxo total. Através da simulação dinâmica ado motor de indução monofásico operando com tensão senoidal e com gradador de tensão um estudo de caso é apresentado, sendo quantificados os ganhos de eficiência em aplicações reais de refrigeradores. Um circuito e método de controle do gradador de tensão com foco na melhor relação custo/eficiência é sugerido. Um novo projeto do motor estuda do é realizado para avaliar a aplicação do grada dor de tensão como dispositivo capaz de ampliar a faixa de tensão de operação de compressor sem regiões com baixa qualidade de energia, mantendo características de eficiência próxima são projeto original.

O presente trabalho realiza o estudo e aplicação de um algoritmo de branch-and-price para a resolução de um problema de escalonamento de compressores. O problema é ligado à produção petrolífera, o qual consiste em definir um conjunto de compressores a serem ativados para fornecer gas de elevação a um conjunto de poços, atendendo toda demanda e minimizando os custos envolvidos. O problema é caracterizado por uma função objetivo não-convexa que é linearizada por partes de forma a ser formulada como um problema de programação inteira mista. A abordagem de geração de colunas é baseada na decomposição de Dantzig-Wolfe e apresenta melhores limitantes inferiores em relação à relaxação linear da formulação compacta. O branch-and-price é comparado ao solver CPLEX, sendo capaz de encontrar a solução ótima em menor tempo para um conjunto de instâncias, bem como melhores soluções factíveis para instâncias maiores em um período de tempo limitado. / This work presents the study and application of a branch-and-price algorithm for solving a compressor scheduling problem. The problem is related to oil production and consists of defining a set of compressors to be activated, supplying the gas-lift demand of a set of wells and minimizing the associated costs. The problem has a non-convex objective function, to which a piecewise-linear formulation has been proposed. This dissertation proposes a column generation approach based on the Dantzig-Wolfe decomposition, which achieves tighter lower bounds than the straightforward linear relaxation of the piecewise-linear formulation. The column generation was embedded in a branch-and-price algorithm and further compared with CPLEX, obtaining optimal solutions in lesser time for a set of instances. Further, the branch-and-price algorithm can find better feasible solutions for large instances under a limited processing time.

Mean Value Engine Modeling (MVEM) is used to make engine control development less expensive. With more and more cars equipped with turbocharged engines good turbo MVEM models are needed. A turbocharger consists of two major parts: turbine and compressor. Whereas the turbine is relatively durable, there exist phenomenons on the compressor that can destroy the turbocharger. One of these is surge. Several compressor models are developed in this thesis. Methods to determine the compressor model parameters are proposed and discussed both for the stable operating range as well as for the surge region of a compressor map. For the stationary region methods to automatically parameterize the compressor model are developed. For the unstable surge region methods to get good agreement for desired surge properties are discussed. The parameter sensitivity of the different surge properties is also discussed. A validation of the compressor model shows that it gives good agreement to data, both for the stationary region as well as the surge region. Different open loop and closed loop controllers as well as different performance variables are developed and discussed. A benchmark is developed, based on a measured vehicle acceleration, and the control approaches are compared using this benchmark. The best controller is found to be a open loop controller based on throttle and surge valve mass flow.

Critical equipment plays an essential role in industry because of its lack of redundancy. Failure of critical equipment results in a major economic burden that will affect the profit of the enterprise. Lack of redundancy for critical equipment occurs because of the high cost of the equipment usually combined with its high reliability. <p><p>When we are analyzing the reliability of such equipment, as a result, there are few opportunities to crash a few pieces of equipment to actually verify component life. <p><p>Reliability is the probability that an item can perform its intended function for a specified interval of time under stated conditions and achieve low long-term cost of ownership for the system considering cost alternatives. From the economical standpoint, the overriding reliability issue is cost, particularly the cost of unreliability of existing equipment caused by failures. <p><p>Classical questions about reliability are:<p><p>·\ / Doctorat en sciences appliquées / info:eu-repo/semantics/nonPublished

Cette thèse est une contribution au problème du contrôle et de la gestion de l'énergie dans le cadre des systèmes hybrides à base de pompe à chaleur à entrée variable. Après un état de l'art sur les systèmes énergétiques et les pompe à chaleur, une présentation des outils expérimentaux, conçus et exploités tout le long de la thèse, est donnée. La troisième partie est constituée de la modélisation physique de la pompe à chaleur. Il s'agit du composant central utilisé pour le contrôle du système hybride. Ensuite, la stratégie de contrôle est décrite et validée à travers des résultats de simulation puis des expérimentations. La dernière partie est dédiée à la gestion d'énergie du système hybride. Plus précisément, un algorithme permettant d'optimiser l'énergie produite est proposé, puis, validé sur des sites représentatifs en France ; le cas d'étude considéré. / This thesis is a contribution to the problem of control and management of energy within the heat-pump-based hybrid systems with variable input power. After a state of the art on energy systems and heat pump, a presentation of experimental tools, designed and operated throughout the thesis is given. The third part consists of the physical modeling of the heat pump. This is the central component used for the control of the hybrid system. Then, the control strategy is described and validated through the simulation results and the experiments. The last part is dedicated to the energy management of hybrid system. Specifically, an algorithm to optimize the energy produced is proposed and validated on representative sites in France ; the study-case of this work.

Howden ČKD Compressors s.r.o. is a mechanical engineering company, which manufactures modern high-tech products, particularly industrial compressors, medium and large capacity electric motors and generators. The company provides its customers with complex technical services and supplies spare parts for different types of industrial equipment. The profound experience in manufacturing and business, technological basis, experienced design department and the existence of highly qualified staff help firm to satisfy client's highest requirements. The main objective of this thesis is analysis of present business activities and creating concept of competitive strategy for Russian Federation.