Content removed due to copyright restriction: Nixon, M. (2001). What are the potential benefits of eel consumption for Maori health? Te Taarere aa Tawhaki 1, 132-135. / This ground breaking doctoral thesis brings together science, history and the values derived from lore and tikanga to address a significant health issue for contemporary Maaori. The specific contribution of this research thesis is the combination of knowledge bases from two perspectives. The thesis first presents a scientific view, then a Maaori view, discovered through an interface of customary and contemporary knowledge. The method first examines Western academic theoretical methodologies, then, Kaupapa Maaori methodologies, then introduces and develops the concept of inherited knowledge supported by the mandatory Standards required in an academic context. Therefore the major findings present the syntheses of the two approaches. The framework used is reproducible through an accepted or approved example of something against which others are judged or measured. At this point the thesis explores the theoretical framework for a health intervention by surveying whether it is possible to combine knowledge traditions in a contemporary setting. Thus the accessed inherited traditional and scientific knowledge discovered in this thesis has been adapted for the nine point health intervention designed for Maaori participation. This thesis hypothesises that the staple long finned eel diet contained the essential fatty acid omega-3 and is presented as a metaphor for Hauora, thus being consistent with modern scientific knowledge where the scientific findings presented. The long finned eel was chemically assayed for the presence of the unsaturated essential fatty acid omega-3, and assayed again to assess the stability and quality of fresh and smoked eel. Type II diabetes mellitus is offered as a story and why it has suddenly occurred in Maaori subsequent to urban migration and thereafter. In addition a ten year study of Waikato hapuu supports the research that regular consumption of the long finned eel prevents Type II diabetes. And that prior to urban migration holistic practice, through established lifestyle choices and inherited knowledge, provided nutritional, other physiological benefits and broader wellness outcomes. The double vowel has been used for all te reo Maaori words in the thesis because that is the kawa or protocol of the Tainui Kiingitanga.

Content removed due to copyright restriction: Nixon, M. (2001). What are the potential benefits of eel consumption for Maori health? Te Taarere aa Tawhaki 1, 132-135. / This ground breaking doctoral thesis brings together science, history and the values derived from lore and tikanga to address a significant health issue for contemporary Maaori. The specific contribution of this research thesis is the combination of knowledge bases from two perspectives. The thesis first presents a scientific view, then a Maaori view, discovered through an interface of customary and contemporary knowledge. The method first examines Western academic theoretical methodologies, then, Kaupapa Maaori methodologies, then introduces and develops the concept of inherited knowledge supported by the mandatory Standards required in an academic context. Therefore the major findings present the syntheses of the two approaches. The framework used is reproducible through an accepted or approved example of something against which others are judged or measured. At this point the thesis explores the theoretical framework for a health intervention by surveying whether it is possible to combine knowledge traditions in a contemporary setting. Thus the accessed inherited traditional and scientific knowledge discovered in this thesis has been adapted for the nine point health intervention designed for Maaori participation. This thesis hypothesises that the staple long finned eel diet contained the essential fatty acid omega-3 and is presented as a metaphor for Hauora, thus being consistent with modern scientific knowledge where the scientific findings presented. The long finned eel was chemically assayed for the presence of the unsaturated essential fatty acid omega-3, and assayed again to assess the stability and quality of fresh and smoked eel. Type II diabetes mellitus is offered as a story and why it has suddenly occurred in Maaori subsequent to urban migration and thereafter. In addition a ten year study of Waikato hapuu supports the research that regular consumption of the long finned eel prevents Type II diabetes. And that prior to urban migration holistic practice, through established lifestyle choices and inherited knowledge, provided nutritional, other physiological benefits and broader wellness outcomes. The double vowel has been used for all te reo Maaori words in the thesis because that is the kawa or protocol of the Tainui Kiingitanga.

In 21 century finned surfaces are used in almost all condensers to enhance their heat transfer capabilities. A lot of different models are presented in the literature: on horizontal and vertical finned tubes, inside finned tubes. The validation method of the theoretical models is based on comparison between measurement of average heat transfer coefficient and one calculated by the model. But in this case it is impossible to validate all approaches made in the theory.<p>\ / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

Die Übertragung thermischer Energie durch Wärmeübertrager ist ein essentieller Vorgang in unterschiedlichen, technischen Prozessen. Die am häufigsten vorkommende Wärmeübertragerbauform bei der Wärmeabgabe an ein Gas ist der Rippenrohrwärmeübertrager. Bis zu 85 % des thermischen Widerstandes treten nach Wang et al. (2002) dabei gasseitig auf, weshalb eine Verbesserung des Wärmeüberganges wesentlich zur Erhöhung der Gesamtleistung beiträgt. Eine typische Anwendung von geneigten Rippenrohren sind luftgekühlte Kondensatoren. Der Einfluss der Rohrneigung auf die Wärmeübertragungs- und Strömungscharakteristik von Rippenrohren wurde in der Literatur bislang kaum untersucht. Luftgekühlte Kondensatoren werden allerdings in geneigter Orientierung installiert, um einen Kondensatablauf auf der Rohrinnenseite zu ermöglichen. Daher würde der Auslegungsprozess von luftgekühlten Kondensatoren wesentlich von einer experimentellen Charakterisierung des Einflusses der Rohrneigung auf die Wärmeübertragungs- und Strömungscharakteristik profitieren. Es existiert eine Vielzahl von Rippendesigns zur Erhöhung der luftseitigen Turbulenz entlang der Rippenoberfläche. In der Literatur konnten keine Rippendesigns gefunden werden, welche neben der Turbulenzerzeugung auch die Wärmeleitung von der Rippenbasis zur Rippenspitze verbessern und somit eine homogenere Temperaturverteilung erreichen. Wissenschaftliche Arbeiten zur Naturkonvektion beschränken sich auf numerische und experimentelle Analysen von berippten Einzelrohren. Rippenrohrbündel unter Naturkonvektion sowie der Einfluss der relevanten Rippen- und Rohrparameter auf die Wärmeübertragung der Rohrbündel wurde bislang kaum untersucht. Für die experimentellen Untersuchungen wurde ein 6,5 m langer vertikaler Strömungskanal errichtet, in welchem unterschiedliche Gleichrichter zur Homogenisierung der Strömung installiert waren. Mittels einer Kombination aus analytischen Näherungsverfahren und Vermessung der lokal aufgelösten Rippenoberflächentemperatur wurde der Rippenwirkungsgrad bestimmt. Die Neigung der Rohrachse gegenüber der Horizontalen erhöht die Nusselt-Zahl bei erzwungener Konvektion und erniedrigt diese bei natürlicher Konvektion. Bei erzwungener Konvektion ist das Leistungsverhalten der Wärmeübertrager unter geneigter Orientierung aufgrund des höheren Druckverlustes reduziert. Für beide Konvektionsarten sinkt der Einfluss des Neigungswinkels auf die Nusselt-Zahl mit abnehmendem Rippenabstand. Basierend auf den experimentellen Untersuchungen wurden Korrelationen entwickelt, um den Wärmeübergang in Abhängigkeit von der Reynolds-Zahl oder Rayleigh-Zahl, dem Neigungswinkel und dem Rippenabstand zu beschreiben. Die existierenden Rippendesigns zielen darauf ab, den gasseitigen konvektiven Wärmeübergang zu verbessern. Die Steigerung der Wärmeleitung durch das Rippendesign wird dabei weitestgehend vernachlässigt. Die Beeinflussung der Wärmeleitung, beispielsweise durch Veränderung des wärmeleitenden Querschnittes entlang des Rippenumfanges, ist durch konventionelle Fertigungstechnologien nur schwierig oder gar nicht realisierbar. Mit neuartigen Herstellungsverfahren, wie der additiven Fertigung, können diese komplexen Geometrien erzeugt und somit auch die Wärmeleitung lokal erhöht werden. Bei der additiven Fertigung wird ein Pulverbett selektiv mit einem Laser oder Elektronenstrahl aufgeschmolzen und das Bauteil schrittweise generiert. In der vorliegenden Arbeit wurde diese Technologie genutzt, um Rippen mit verstärkenden, in der Rippenoberfläche integrierten, Stiften zu fertigen. Dadurch werden die Wärmeleitung und die Konvektion entlang der Rippenoberfläche verbessert. Zwei neuartige Designs wurden additiv gefertigt, experimentell in einem vertikalen Strömungskanal charakterisiert und patentiert. Bei den Untersuchungen wurde festgestellt, dass das Leistungsbewertungskriterium der geschlitzten integrierten Stiftrippe (SIPF) um 78,5 % höher und die Kompaktheit der runden integrierten Stiftrippe (CIPF) um 24,3 % höher ist als bei der konventionellen glatten Rohrrippe. Die Rohre mit neuartigem Rippendesign wurden auch unter verschiedenen Neigungswinkeln untersucht. Die Zunahme des Druckverlustes mit dem Rohrneigungswinkel ist niedriger als bei der konventionellen Rippe. Die SIPF erreicht bei einer Neigung von α=20 ° das höchste Leistungsverhalten und die CIPF erreicht bei α=40 ° Neigung die höchste volumetrische Wärmestromdichte. Die entwickelten Korrelationen beschreiben die Abhängigkeit dieser Designs von der Reynolds-Zahl für verschiedene Rippenabstände sowie von der Reynolds-Zahl für verschiedenen Neigungswinkel. Eine typische Anwendung von geneigten Rippenrohren sind luftgekühlte Kondensatoren, bei denen die Erfassung der thermischen Wärmeübertragungsleistung auf der Rohrinnenseite aufgrund des Phasenwechsels unter Umständen schwierig ist. Eine neue Messtechnik, der Temperatur-Anemometrie-Gittersensor (TAGS), wurde genutzt, um die luftseitige Temperatur und Strömungsgeschwindigkeit zeitgleich und ortsaufgelöst zur ermitteln. Die gemessene Temperaturverteilung ist für geneigte Rippenrohre stark ungleich verteilt. Fünf verschiedene Varianten zur Berechnung der thermischen Wärmeübertragungsleistung werden miteinander verglichen. Die Bestimmung mittels gewichteter Wärmestromdichten zeigt dabei die geringsten Abweichungen. Der numerische Strömungsberechnungscode ANSYS CFX 19.0 wurde verwendet, um den Einfluss der Rippen- und Rohrparameter auf die Naturkonvektion von Rippenrohrbündeln qualitativ zu analysieren. Basierend auf der numerischen Studie wurden die zu optimierenden Rippen- und Rohrparameter ausgewählt. Zu diesen Parametern zählen die Rippendicke, der Rippenabstand, die Rippenhöhe, das Rohrachsenverhältnis, die Rohranordnung, die transversalen und longitudinalen Rohrabstände sowie die Rohrreihenanzahl. Diese Optimierung wurde mit Erkenntnissen bezüglich der erzwungenen Konvektion aus der Literatur kombiniert, wobei das ovale Rippenrohrbündel ein Achsenverhältnis von 1:2, eine Rippendicke von 1 mm, einen Rippenabstand von 5 mm und eine Rippenhöhe von 17 mm hat. Die versetzte Anordnung hat einen longitudinalen Rohrabstand von 63 mm sowie einen transversalen Rohrabstand von 53 mm und wurde in zwei- und dreireihiger Rohrreihenanzahl ausgeführt. Numerische Simulationen dieses optimierten Wärmeübertragers wurden für Naturkonvektion und für erzwungene Konvektion durchgeführt und qualitativ verglichen. Die Simulationsergebnisse zeigen für beide Konvektionsarten ähnliche Strömungsphänomene, wie beispielsweise Staupunkte am Rohr, Nachlaufgebiete stromabwärts des Rohres und Beschleunigungsbereich zwischen den Rohrrippen. Die optimierten Rohrbündelwärmeübertrager wurden mit konventionellen Rippen und den neuartigen Rohrrippen in zweireihiger und dreireihiger Ausführung realisiert. In einer dafür angepassten Testsektion wurden die experimentellen Untersuchungen durchgeführt. Im Vergleich zur konventionellen Rippe zeigt die SIPF ein höheres Leistungsbewertungskriterium und eine um 52 % höhere Nusselt-Zahl für beide Ausführungen. Die CIPF erreicht eine um 22,4 % und 27,8 % höhere volumetrische Wärmestromdichte für die zweireihige und dreireihige Ausführung verglichen mit der konventionellen Rippe. Die Ergebnisse der experimentellen Untersuchungen der Rohrbündelwärmeübertrager unter Naturkonvektion in einem Kamin zeigen durchschnittlich 19,7 % und 10,9 % höhere Nusselt-Zahlen sowie 11,2 % und 4,0 % höhere volumetrische Wärmestromdichten der SIPF für die dreireihigen und zweireihigen Wärmeübertrager im Vergleich zum konventionellen Design. Ein verbessertes thermisches Leistungsverhalten für CIPF bei Naturkonvektion ist nicht zu erkennen. Diese Arbeit zeigt, wie durch moderne Fertigungsverfahren und neue Designs auch Komponenten mit einem hohen technologischen Reifegrad weiter optimiert werden können. Durch verbesserte Wärmeübertragungsleistung bei gleichzeitig niedrigerem Materialverbrauch können Wärmeübertrager effizienter und ressourcenschonender hergestellt und betrieben werden. / The transfer of heat is an essential process in many technical applications and is usually realized by heat exchangers. The most common design to transfer heat to a gas is the finned tube bundle heat exchanger. Since up to 85 % of the thermal resistance occur on the gas side, an improvement of the heat transfer from the wall into the gas would increase the total thermal performance significantly (Wang et al., 2002). The influence of tilted tubes on the thermal and flow performance of finned tubes has rarely been studied so far. This tilted orientation is of particular relevance for air cooled condensers, to allow liquid drainage inside the tube. Several fin designs were developed to enhance the air side flow mixing along the fin surface. However, a fin design which induces turbulence and simultaneously improves the heat conduction was not found in literature. The literature study evinces a focus of numerical and experimental work on natural convection of single finned tubes. In contrast to single tubes, the natural convection of finned tube bundles has been barely investigated so far. Especially the influence of fin and tube parameters as well as the fin design was mostly neglected for finned tube bundles at natural convection. A 6.5 𝑚 long vertical flow channel, including a flow straightener to homogenize the flow, was erected for the experimental investigations. The fin temperature was determined by a combination of an analytical approximation method and locally resolved temperature measurements. It was used to calculate the fin efficiency. The tube tilt angle increases the Nusselt number for forced convection and reduces the Nusselt number for natural convection. For forced convection the performance of the heat exchanger reduces with tube tilt angle due to the higher pressure drop. As the fin spacing reduces the influence of the tube tilt angle becomes small for both types of convection. Based on the experimental outcome correlations were developed to predict the heat transfer as a function of Reynolds number or Rayleigh number, the tube tilt angle and the fin spacing. The existing fin designs aim to improve the convective heat transfer and the heat conduction is mostly neglected. The influence on the heat conduction, e. g. by strengthening of the cross section for heat conduction along the fin circumference, is difficult or impossible to be achieved by conventional manufacturing technologies. Novel production techniques, such as additive manufacturing, allow the generation of complex geometries. In an additive manufacturing process a powder bed is selectively melted by a laser or electron beam, to stepwise generate the component. In the present study this technology was applied to produce fin surfaces with integrated pins to enhance the heat conduction within the fin and to improve convection along the fin surface. Two novel patented designs were developed and experimentally characterized in the flow channel. It was found, that the performance evaluation criterion of the serrated integrated pin fin (SIPF) is 78.5 % higher and the compactness of the circular integrated pin fin (CIPF) is 24.3 % higher compared to the convectional, plain fin (CPF). The tubes were also studied for various tube tilt angles. A smaller increase of the pressure drop occurs for the novel fin designs at higher tube tilt angle compared to the conventional design. The SIPF achieves the greatest performance at a tube tilt angle of 𝛼=20 ° and the CIPF achieves the highest volumetric heat flux density at 𝛼=40 °. An empirical correlation predicts the heat transfer from the designs depending on the Reynolds number for different fin spacing as well as on the Reynolds number for different tube tilt angle. Tilted finned tube heat exchangers are typically used as air-cooled condensers, where the determination of thermal heat transfer may be intricate on the tube inside due to the phase change. Therefore, a new sensor, the Temperature Anemometry Grid Sensor (TAGS), was used to measure the local and time resolved air side temperature and velocity distribution. For the tilted finned tubes a strongly inhomogeneous temperature distribution was measured. Five different approaches were compared to calculate the thermal power. The method with weighted heat flux densities gives the lowest deviation. The numerical fluid dynamics code ANSYS CFX 19.0 was applied to analyze the influence of fin and tube bundle parameters on the natural convection from finned tube bundles. Based on the numerical investigation the fin parameters, such as fin thickness, fin spacing and fin height as well as the tube bundle parameters, such as tube axis ratio, tube arrangement, transversal tube pitch, longitudinal tube pitch and tube row number, were optimized. These results were used together with data from literature to determine an optimal tube bundle. It has an axis ratio of 1:2, a fin thickness of 1 𝑚𝑚, a fin spacing of 5 𝑚𝑚 and a fin height of 17 𝑚𝑚. The staggered arrangement has a longitudinal tube pitch of 63 𝑚𝑚, a transversal tube pitch of 53 𝑚𝑚 and a tube row number between two and three. The optimized heat exchangers were simulated for forced and natural convection and the results are qualitatively compared. From these results the finned tube bundle configurations were generated for the conventional and the two novel fin designs in a two and three row arrangement. It was found, that for forced convection the SIPF give a higher thermal and flow performance as well as a 52 % greater Nusselt number compared to the conventional design for both arrangements. Furthermore, the CIPF achieves 22.4 % and 27.8 % higher volumetric heat flux density compared to the conventional design for the two row and three row arrangement. The experimental investigation of the tube bundle configurations under natural convection in a chimney show 19.7 % and 10.9 % greater Nusselt numbers as well as 11.2 % and 4.0 % higher volumetric heat flux density for the SIPF with three row and two row heat exchangers respectively compared to the conventional design. The CIPF does not achieve higher thermal performance for natural convection. The present investigation illustrates, that the application of modern manufacturing technologies and designs can further improve components, which are already at a high degree of maturity. The enhanced heat transfer and the simultaneous reduction of material consumption allows the development and operation of efficient and sustainable heat exchangers.

Skeletal (cartilaginous, bony, and dental) tissues undoubtedly exemplify the key innovation of vertebrates. Among all recent vertebrates, the most numerous and successful lineage is represented by the Ray-finned fishes that, accordingly, exhibit amazing variety of skeletal architectures and phenotypic adaptations. In order to depict fundamental principles of fish cranial skeletogenesis the developmental formation of skeletal architectures was described, compared and analyzed using members of early branching fish lineages, that exemplify very different strategies of skeletogenesis. While the Senegal bichirs and the Tropical gars are heavily armored forms with massive exoskeleton and hyperossified dental structures covering the whole oropharyngeal region, the European sterlets, on the contrary, possess mostly cartilaginous skeleton and reduce their dental structures during early development. Whole analysis is underpinned by the Northen pike, teleostean species with lightened skeletal architecture with comparable number of cranial elements. The present study represents the first complex comparative analysis of their skeletogenesis and odontogenesis. This allowed to define developmental strategies founding different lineage-specific skeletal architecture of vertebrates. Comparative description of...

Aggressive demands for high power density and low-cost power modules in the automotive sector pose significant challenges to the thermal management systems. These challenges necessitate adopting highly effective cooling technologies in power modules to remain competitive in the semiconductor industry. Furthermore, the thermal management strategy must be simple, easy to integrate, compact, effective, efficient, reliable, and economical. This thesis is an effort to investigate the impact of fin geometry on the overall performance of finned-type liquid-cooled power electronic modules in electrified transportation. The cooling system's performance metrics, including thermal resistance, pressure drop, pumping power, and mass, are discussed in depth. Various cooling technologies are benchmarked. The finned-type cooling technique is chosen over other methods due to simplicity and low pressure drop. Integrated cooling or direct cooling of the module’s baseplate is selected due to considerable thermal resistance reduction because of thermal grease elimination. Potential fabrication techniques are thoroughly explored and compared in terms of mass production and prototyping suitability. Four different fin shapes, including circular (baseline), drop-shaped, symmetric convex lens, and offset strip in the staggered arrangement, are studied herein. The cooling agent is Water and Ethylene Glycol 50% volumetric mixture (WEG 50%). Typical operating conditions in electrified vehicles (EVs) such as flow rate and inlet temperature are assumed for the numerical analysis. A grid convergence study is carried out to ensure numerical solutions are within an acceptable error band. The thermal performance evaluation results showed that, on average, offset strip, drop-shaped, and the convex lens performed 39%, 20%, and 6% better than the baseline design, respectively. Additionally, the design candidates are compared in terms of mass and estimated machining cost. The results of the baseline case are verified against empirical correlations from the literature. The maximum deviation is less than 1% and 1.2% for finned-surface temperature and pressure drop, respectively. The difference is attributed to the end-wall effects. / Thesis / Master of Applied Science (MASc)

Dentition is a key vertebrate innovation showing not only great morphological diversity, but also different maintenance or replacement of functional teeth. Most extant vertebrates replace their dentition through addition of new teeth from deeply invaginated epithelium, i.e. the successional dental lamina, due to presence of dental stem cells. However, in some early branching lineages of ray-finned fishes (Actinopterygii), new tooth germs arise from the adjacent superficial epithelium without the presence of the successional dental lamina. Whether the two types of dental development in vertebrates are equivalent and whether comparable dental stem cells play role in tooth replacement is currently not satisfactorily evaluated. This Master thesis aims at describing the development of palatal and pharyngeal dentition of a member of an early branching lineage of ray-finned fishes, the sterlet sturgeon (Acipenser ruthenus). The sterlet dentition is fairly dynamic. The teeth are replaced without the successional dental lamina, however, this replacement shows characteristics similar to those described in vertebrates with the successional dental lamina. A marker of dental stem/progenitor cells, Sox2, is localized in the outer dental epithelium of the predecessor tooth in the vicinity of the adjacent taste...

The Master’s thesis dealing with air-cooled condensers is split into four sections. The first section shows an overview of air cooling, introduction into air-cooled condensers of A-frame shape and finned tubes. The second section deals with heat transfer on the steam side and deals with trapped incondensables on the steam side of ACC. The third section deals with heat transfer on the air side, shows a brief overview of fans and selected problems on the air side. In the last section the simplified thedmodynamic calculation of air-cooled condenser is shown.

[pt] Em sistemas de refrigeração por compressão de vapor, o projeto adequado dos circuitos para o refrigerante nos trocadores de calor pode ter um impacto significativo no seu coeficiente de performance (COP). O projeto otimizado dos circuitos de refrigerante em sistemas de refrigeração com trocadores de calor do tipo tubo-aletado não é trivial, devido à complexidade de sua representação assim como o elevado número de possíveis combinações, mesmo quando metodologias inteligentes de otimização são empregadas. No presente trabalho propõe-se uma nova metodologia para a otimização simultânea (condensador e evaporador) dos circuitos do refrigerante em sistemas de refrigeração com trocadores de calor de tipo tubo-aletado. Esta metodologia, aqui denominada como GAFIS (Genetic algorithms applied in filtered spaces), mostra-se mais eficiente que as metodologias até então descritas na literatura. Foi aplicado o método GAFIS, em conjunto com um simulador completo para o sistema de refrigeração, Genesym, na otimização de unidades comerciais de condicionamento de ar de alto desempenho. Estudaram-se casos onde o sistema atingiu aumentos de até 15,3 por cento no coeficiente de performance. Em outros estudos, obtiveram-se casos onde o custo de produção foi reduzido em 3,85 por cento (do custo total da unidade), mantendo-se um similar desempenho (capacidade e COP). Testes de otimização, considerando-se diferentes diâmetros dos tubos, na construção dos trocadores de calor, e sistemas com distribuição não uniforme de velocidade de ar, também foram realizados com o GAFIS. Igualmente foram estudados condensadores de microcanais, devido ao interesse atual da indústria com estes trocadores de calor. A otimização do circuito para o refrigerante, neste caso, é relativamente simples, devido ao baixo custo computacional das simulações. Entretanto, modelos de simulação adequados para estes tipos de trocadores de calor só recentemente começaram a surgir, e não têm sido explorados de maneira adequada até a presente data. Explorou-se no presente trabalho, a influência, no desempenho térmico do condensador, dos parâmetros que definem o circuito do refrigerante. Para tal efeito, desenvolveu-se um modelo de simulação baseado em análise local, validado com dados experimentais disponíveis, de condensadores de microcanais de uso automotivo com diâmetro hidráulico (lado do refrigerante) de 0,9 e 1,0mm, para refrigerantes R-134a, Fluid-H e R-1234yf. Foram encontradas relações diretas entre os parâmetros geométricos que definem os circuitos de refrigerante no condensador e seu desempenho térmico. Tal fato pode ser utilizado como orientação expedita para o projeto do circuito ótimo do condensador. / [en] Refrigerant circuiting in condensers and evaporators has a significant effect in the performance of refrigeration systems. The optimized project of the refrigerant circuits in refrigeration systems with plate-fin heat exchangers is not trivial, due to the complexity of their representation as well as the high number of possible combinations, even when methodologies of intelligent optimization are used. The present work proposes a new methodology for the simultaneous optimization of refrigerant circuiting in air-air refrigeration systems with plate-fin heat exchangers. This new methodology, here defined as GAFIS (Genetic algorithms applied in filtered spaces), has proven to be more efficient than traditional methods. The GAFIS method was applied, in conjunction with a full refrigeration system simulator, Genesym, for the optimization of high performance commercial air-conditioning units. Typical cases were studied and a coefficient of performance improvement of up to 15.3 percent has been observed. In other studies, there were cases where the manufacturer s predicted cost was reduced in 3,85 percent (of total cost of the unit), while a similar thermal performance (capacity and COP) was maintained. Optimization tests, considering different diameters of tube, for the construction of heat exchangers, as well as systems with non-uniform air velocity distribution, were also performed with the GAFIS method. Microchannel condensers were also studied, given the current interest of industry on this kind of heat exchanger. The optimization of the refrigerant circuiting, in this case, would not be a major problem, due to the low computational cost of its simulation. However, simulation models appropriate for these types of heat exchangers have only been recently in use, and, to date, have not been adequately explored. In the present work, the influence on condenser performance of parameters that define the refrigerant circuiting has been investigated. For this purpose, a simulation model, based on local analysis, was developed. It was validated against experimental data, available from automotive microchannel condenser tests, with hydraulic diameters (refrigerantside) of 0.9 and 1.0mm for refrigerants R-134a, Fluid-H and R-1234yf. A direct relation was found between the geometric parameters that define the condenser refrigerant circuiting and its thermal performance. This fact can be appropriately used as guidance for expeditious design practices of the optimal refrigerant circuit of the condenser.

The task of the diploma thesis named VBA and Maple Application on Process Engineering Problems is to show the possibilities of using these programming languages for various engineering tasks. Particularly the programming language Visual Basic for Application (VBA), which is a part of MS Office package, is very little used in practise. That´s why this thesis solves the complex task of a furnaces design process; the topic was reccomended by the supervisor prof. Ing. Josef Kohoutek, CSc. Specifically, the thesis deals with calculations of heat transfer and optimization of the height of extended surfaces of tubes in the convection section of process furnaces. The entire task is elaborated in VBA and runs in Excel. After entering the input information, the created program first calculates the size and heat output of the convection section, but it can also optimize the height of extended surfaces in different parts of the convection section and thus minimize investment costs.