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[ES] El proyecto de tesis de máster consiste en un equipo experimental que pretende emular diferentes etapas de la transferencia de calor circunferencial alrededor de un tubo horizontal con una placa inclinada, con el fin de aportar conocimientos sobre la transferencia de calor a baja temperatura con flujo de película descendente. Consiste en un recipiente de vacío en el que el flujo de película descendente se distribuye sobre la placa calefactora inclinada y se evapora parcialmente. La placa está equipada con termopares incrustados en cinco posiciones. Además, se utiliza una sonda termopar insertada en la película para medir la temperatura en el flujo de película descendente. El espesor de la película se mide con un sensor confocal de cromaticidad. La temperatura del líquido en la entrada y la salida se mide con un termómetro de resistencia Pt100. El caudal másico y la densidad del fluido de trabajo se miden con un caudalímetro Coriolis. Las principales tareas del proyecto consisten en Evaluación del comportamiento de los termopares frente a las variaciones de temperatura del sensor de referencia externo, instalación de los termopares en la placa, calibración de los termopares y de los termómetros de resistencia, verificación de la medición de la temperatura de la placa mediante termografía infrarroja, instalación de la sonda de termopar y desarrollo de los primeros experimentos de medición de la temperatura de la película en condiciones de evaporación al vacío para obtener valores consistentes del coeficiente de transferencia de calor con agua como fluido de trabajo., [EN] The master's thesis project consists of experimental equipment that aims to emulate different stages of circumferential heat transfer around a horizontal tube with an inclined plate in order to provide knowledge on low-temperature heat transfer with falling film flow. It consists of a vacuum vessel in which the falling film flow is distributed over the inclined heating plate and partially evaporates. The plate is equipped with thermocouples embedded in five positions. In addition, a thermocouple probe inserted in the film is used to measure the temperature in the falling film stream. The film thickness is measured with a confocal chromaticity sensor. The liquid temperature at the inlet and outlet is measured with a Pt100 resistance thermometer. The mass flow and density of the working fluid is measured with a Coriolis flowmeter. The main tasks of the project consist of: Evaluation of the behaviour of the thermocouples against temperature variations in the external reference sensor, installation of the thermocouples on the plate, calibration of the thermocouples and resistance thermometers, verification of the plate temperature measurement by infrared thermography, installation of the thermocouple probe and development of the first experiments measuring the film temperature under vacuum evaporation conditions in order to obtain consistent values of heat transfer coefficient with water as a working fluid., [DE] Das Masterarbeitsprojekt besteht aus einer Versuchsanlage, mit der verschiedene Stadien der Umfangswärmeübertragung um ein horizontales Rohr mit einer geneigten Platte nachgebildet werden sollen, um Erkenntnisse über die Niedertemperatur-Wärmeübertragung mit Fallfilmströmung zu gewinnen. Sie besteht aus einem Vakuumgefäß, in dem der Fallfilmstrom über die geneigte Heizplatte verteilt wird und teilweise verdampft. Die Platte ist mit Thermoelementen ausgestattet, die an fünf Stellen angebracht sind. Außerdem wird mit einer in den Film eingeführten Thermoelement-Sonde die Temperatur im Fallfilmstrom gemessen. Die Schichtdicke wird mit einem konfokalen Chromatizitätssensor gemessen. Die Flüssigkeitstemperatur am Einlass und Auslass wird mit einem Pt100-Widerstandsthermometer gemessen. Der Massenstrom und die Dichte der Arbeitsflüssigkeit werden mit einem CoriolisDurchflussmesser gemessen. Die Hauptaufgaben des Projekts bestehen in: Bewertung des Verhaltens der Thermoelemente gegenüber Temperaturschwankungen im externen Referenzsensor, Installation der Thermoelemente auf der Platte, Kalibrierung der Thermoelemente und Widerstandsthermometer, Überprüfung der Plattentemperaturmessung durch InfrarotThermografie, Installation der Thermoelement-Sonde und Entwicklung der ersten Experimente zur Messung der Filmtemperatur unter Vakuumverdampfungsbedingungen, um konsistente Werte des Wärmeübergangskoeffizienten mit Wasser als Arbeitsflüssigkeit zu erhalten.

Energy is one of the world's critical resources. For this reason, energy saving and efficiency is an important study subject. In order to save energy, there are theoretical and experimental studies in the literature due to the need for the improvement of heat transfer and the compactness of the heat exchangers, and the search for new fluids that will provide heat transfer improvement instead of the traditional fluids used in heat exchangers.In this study, the nanofluids obtained by changing the ratios of Al2O3 and SiO2 high nanoparticles volume fraction instead of low nanoparticles volume fraction and by changing the ratios of the base fluid ethylene glycol-water mixtures, where efficient results were obtained in providing heat transfer improvement, the thermal and hydraulic performance of a concentric, intertwined, parallel and counter flow in a tubular heat exchanger, using hot and cold fluids at different volumetric flows, was investigated numerically. Water on the hot fluid side, 0:100%, 40:60%, 60:40% and 100:0% on the cold fluid side, into different ratios of EG-water at 0%, 2%, 4%, 6% nanoparticles volume fractions and different Reynolds numbers (6000 – 8000 – 12000 – 16000 - 20000) nanofluids obtained by adding Al2O3 and SiO2 nanoparticles were used. According to the results of numerical studies, when the fixed volumetric flow value of hot fluid water is 3 l/min, the constant volumetric flow value of nanofluids is 0.9 l/min and Reynolds number 20000, Al2O3-100:0% EG/water and SiO2-100:0% EG/water. The Nusselt number of nanofluids increased by 15.4% and 9.1%, respectively, compared to 0:100% EG/water. The results showed that the pressure drop in a counter flow tubular heat exchanger is high, as well as the heat exchanger performance is better than the parallel flow, the Nusselt number increases with the solid volume concentration contained in the nanofluid, and both the 0:100% ratio and the SiO2 of the Al2O3-100:0% EG/water nanofluid. SiO2 -100:0% EG/water indicates that it is more effective in increasing the performance of the heat exchanger compared to nanofluid., Enerji dünyanın kritik kaynaklarının başında gelmektedir. Bu sebeple enerji tasarrufu ve verimlilik önemli bir çalışma konusudur. Enerji tasarrufunun sağlanabilmesi için ısı transferinin iyileştirilmesi ile ısı değiştiricilerin kompaktlığı gibi ihtiyaçların doğması ile ısı değiştiricilerde kullanılan geleneksel akışkanların yerine ısı transferi iyileştirmesini sağlayacak yeni akışkan arayışı sebebiyle literatürde teorik ve deneysel çalışmalar bulunmaktadır. Bu çalışmada ısı transferi iyileştirmesinin sağlanmasında verimli sonuçların elde edildiği Al2O3 ve SiO2 nanoparçacıklarının düşük katı hacim yerine yüksek katı hacim oranlarında ve temel akışkan etilen glikol-su karışımlarının oranları değiştirilerek farklı hacimsel debilerde sıcak ve soğuk akışkanların kullanıldığı, eş merkezli, iç içe borulu, paralel ve zıt akışlı bir ısı değiştiricinin ısıl ve hidrolik performansı sayısal olarak incelenmiştir. Sıcak akışkan tarafında su, soğuk akışkan tarafında %0:100, %40:60, %60:40 ve %100:0 olmak üzere farklı oranlardaki etilen glikol-su karışımı içerisine %0, %2, %4, %6 katı hacim konsantrasyonlarında ve farklı Reynolds sayılarında (6000 – 8000 – 12000 – 16000 - 20000) Al2O3 ve SiO2 nanoparçacıkların eklenmesiyle elde edilen nanoakışkanlar kullanılmıştır. Sayısal çalışmaların sonuçlarına göre, zıt akış altında sıcak akışkan olan suyun sabit hacimsel debi değeri 3 l/dk, nanoakışkanların sabit hacimsel debi değeri 0,9 l/dk ve Reynolds sayısı 20000 alındığında, %6 katı hacim oranı için Al2O3-%100:0 EG/su ve SiO2-%100:0 EG/su nanoakışkanlarının Nusselt sayısında, %0:100 EG/su oranına kıyasla sırasıyla %15,4 ve %9,1 oranında artış olmuştur. Sonuçlar, zıt akışlı bir ısı değiştiricideki basınç düşümünün yüksek değerlerde olmasının yanında, Isı değiştirici performasının paralel akışa göre daha iyi olduğunu, nanoakışkanın içerdiği katı hacim oranın artmasıyla Nusselt sayısının arttığını ve Al2O3-%100:0 EG/su nanoakışkanının hem %0:100 EG/su oranına hem de SiO2- %100:0 EG/su nanoakışkanına göre ssı değiştiricinin performansını artırmada daha etkili olduğunu göstermektedir.

PCM emulsions have attracted considerable interest as the media for thermal energy storage (TES) owing to their high thermal storage capacity, desirable fluidity and thermal conductivity. However, the direct transportation of PCM emulsions in TES systems for both charging and discharging is rarely reported. In this work, a PCM-in-water nano-emulsion was prepared with n-hexadecane and suitable surfactants for cooling energy storage at a charging and discharging temperature range of 20–5 °C and 5–15 °C, respectively. It was applied to a tubular heat exchanger system to evaluate its TES performance for a cooling panel of 0.2 m2 total surface area. The thermal storage performance was notably increased with the flow rate of emulsion through the exchanger tube. The volumetric thermal storage capacity of charging was 50% higher than that of water. The cooling energy could be rapidly released in the discharging process, 79% of the stored energy at averaging 25 W during most of the discharging period. The emulsion remained stable throughout the test period. Overall, the results demonstrated that the PCM nano-emulsion has the unique characteristics of high static stability, and high energy releasing efficiency and the promising potential for air-conditioning application in buildings.

Whey protein fractal aggregates reveal different texturizing properties depending on their size. This study characterize the effect of three process parameters (flow regime, heating residence time (RTh) and heating temperature) on the size and shape of aggregates formed at a semi-industrial scale using a dynamic tubular heat exchanger, and identify the mechanisms involved in their formation. The study showed that physicochemical parameters are not the unique levers to modulate agregates properties but process parameters are also efficient. Asymetrical-Flow-Field-Flow-Fractionation was used to highlight the significant increase of aggregate size produced under transient regime conditions compared to laminar and turbulent regimes. Even larger aggregates were obtained while increasing the heating temperature from 80 to 85 °C since the unfolding aggregation of protein was controlled by the aggregation step. Moreover, RTh showed no effect on aggregate formation. This study paves the way to the control of aggregate properties obtained in a continuous dynamic mode.

In food industry, heat treatment of highly viscous fluids in continuous process is more and more common and the process should perform homogenous thermal treatment in order to ensure quality and safety of the final product. To improve treatment homogeneity, geometric modifications could be used even in laminar regime inducing flow perturbation and mixing. In this work, our objectives were (i) to investigate residence time distribution (RTD) for industrial indirect Joule effect heaters (JEH) with smooth (ST) and modified (MT) tubes, (ii) to demonstrate and quantify the efficiency of geometrical modifications and (iii) to propose a general reactor model including flow regime (10

Die vorliegende Arbeit beschreibt einen hybriden Ansatz, der numerische Methoden mit Fuzzy-Systemen für die Beschreibung des Proteinfoulings bei der Erhitzung von Milch kombiniert. Zur Modellvalidierung werden aus dem Prozessleitsystem einer Industrieanlage zur Milcherhitzung gewonnene Prozessparameter (Temperatur, Druck) herangezogen und hinsichtlich des Foulings untersucht. Der numerische Teil des Numero-Fuzzy-Hybrids setzt ein Finite-Volumen-Modell ein. Modellansätze und –daten für das Produkt (Milch) entstammen der Literatur. Die Integration des in einer Vielzahl von in der Literatur genannten Experimenten gewonnenen qualitativen Wissens über die Milchansatzbildung wird über Fuzzy-Systeme integriert. Ein Ansatz zur Untersuchung der Sensitivität der eingesetzten Fuzzy-Systeme, der auf einer differenzierbaren Approximation dieser beruht, wird vorgestellt. The work describes a hybrid approach combining numerical methods with fuzzy-systems for the description of fouling during the heating of milk. For model validation process parameters (temperature, pressure) of an industrial milk heating plant are taken from the process control system and studied with respect to fouling. The numerical part of the numero-fuzzy-hybrid uses a finite-volume-model. Approaches and data for modelling the product (milk) are taken from literature. The integration of the qualitative knowledge obtained in numerous experiments being documented in literature is integrated using fuzzy-systems. An approach to study the sensitivity of the implemented fuzzy-systems by means of a differentiable approximation is presented.