Les fluides naturels employés en réfrigération et en conditionnement d’air possèdent de faibles PRG et sont de ce fait une véritable alternative aux HFC. Cependant, leur généralisation se heurte à des limites provenant de leur caractère toxique (NH3), inflammable (hydrocarbures, NH3) ou de leurs caractéristiques thermodynamiques défavorables (CO2). Leur utilisation accrue nécessite la mise en œuvre de composants spécifiques (échangeurs de chaleur intermédiaire, éjecteur) qui sans qui les performances seraient inférieures à celles obtenues avec les HFC (COPCO2 = 55 % du COPHFC-134a pour des températures de sources de 0 °C et 40 °C). L’utilisation d’un éjecteur comme organe de détente est une solution envisagée pour réduire les irréversibilités. Les éjecteurs diphasiques constituent une alternative intéressante pour les dispositifs de détente classiques utilisés depuis plusieurs décennies. Le principal avantage de l’éjecteur est de récupérer une partie de l’énergie cinétique du processus de détente de la haute pression à la basse pression pour augmenter la pression d’aspiration du compresseur. Ceci entraîne une diminution du travail consommé par ce dernier et, par suite, une augmentation du coefficient de performance du système. Néanmoins, une bonne conception d’un éjecteur diphasique nécessite une analyse détaillée en termes de simulations numériques et travaux expérimentaux. Ainsi, l’objectif de ce travail est d’apporter une contribution expérimentale à l’étude des machines frigorifiques au CO2 transcritique équipées d’éjecteur diphasique. Des efforts importants ont été investis dans la conception d’un éjecteur diphasique avec diverses géométries pour évaluer les principales caractéristiques à savoir le facteur d’entraînement et le rapport de compression. Les essais effectués ont permis de mettre en évidence l’influence des différents paramètres géométriques sur les performances de la machine (différents diamètres au col des tuyères primaires, différents diamètres de mélangeurs, longueurs de mélangeurs, distance entre le plan de sortie de la tuyère primaire et l’entrée du mélangeur, l’angle de divergent des tuyères primaires…) ainsi que les paramètres thermodynamiques (température d’évaporation, température à l’entrée de la tuyère primaire). / Natural refrigerants used in refrigeration and air conditioning have low GWP and are therefore a real alternative to HFCs. However, their generalization comes up against limits due to their toxic (NH3), flammable (hydrocarbons, NH3) or their unfavorable thermodynamic characteristics (CO2). Their increased use requires the implementation of specific components (intermediate heat exchangers, ejector) which without performance would be lower than those obtained with HFCs (COPCO2 = 55% of COPHFC-134a for temperatures source of 0 °C and 40 °C). The use of an ejector as an expansion device is a solution considered to reduce irreversibility. Two-phase ejector has been an interesting alternative for conventional expansion devices for several decades. The main advantage of the ejector is to recover some of the kinetic energy of the process of expansion from high pressure to low pressure to increase the suction pressure of the compressor. This results in a reduction of the work consumed by the latter and, consequently, an increase in the coefficient of performance of the system. Nevertheless, a good design of a two-phase ejector requires a detailed analysis in terms of numerical simulations and experimental work. Thus, the objective of this work is to make an experimental contribution to the study of transcritical CO2refrigeration machines equipped with two-phase ejector. Significant efforts have been invested in the design of a two-phase ejector with various geometries to evaluate the main characteristics namely the entrainment ratio and the compression ratio. The tests carried out made it possible to highlight the influence of the various geometrical parameters on the performances of the machine (different diameters of the throat of the primary nozzle, different mixers diameters and lengths, distance between the exit of the primary nozzle and the inlet of the mixer, the divergence angle of the primary nozzles ...) as well as the thermodynamic parameters (evaporation temperature, temperature at the inlet of the primary nozzle).

A comprehensive study of heat transfer and pressure drop of refrigerant R410A during condensation and supercritical cooling at near-critical pressures was conducted. Investigations were carried out at five nominal pressures: 0.8, 0.9, 1.0, 1.1 and 1.2xpcrit. The refrigerant was tested in commercially available horizontal smooth tubes of 6.2 and 9.4 mm I.D. Heat transfer coefficients were measured using a thermal amplification technique that measures heat duty accurately while also providing refrigerant heat transfer coefficients with low uncertainties. For condensation tests, local heat transfer coefficients and pressure drops were measured for the mass flux range 200 G 800 kg/m2-s in small quality increments over entire vapor-liquid region. For supercritical tests, local heat transfer coefficients and pressure drops were measured for the same mass flux range as in the condensation tests for temperatures ranging from 30 110oC. Condensation heat transfer coefficients and pressure drops increased with quality and mass flux. The effect of reduced pressure on heat transfer is not very significant, while this effect is more pronounced on the pressure gradient. The flow regime transition criteria of Coleman and Garimella (2003) were used to initially designate the prevailing flow regimes for a given combination of mass flux and quality. The condensation data collected in the present study were primarily in the wavy and annular flow regimes. During supercritical cooling, the sharp variations in thermophysical properties in the vicinity of the critical temperature resulted in sharp peaks in the heat transfer coefficients and sudden jumps in the pressure drop. Based on the characteristics of the specific work of thermal expansion (contraction), the data from the supercritical tests were grouped into three regimes: liquid-like, pseudo-critical transition and gas-like regimes. Flow regime-based heat transfer and pressure drop models were developed for both condensation and supercritical cooling. For condensation, the overall heat transfer model predicts 98% of the data within 15% while the overall pressure drop model predicts 87% of the data within 15%. For supercritical cooling, the heat transfer model predicted 88% of the data within 25% while the pressure gradient model predicts 84% of the data within 25%.

Concern with global climate change has led to the interest in the use of natural refrigerants, such as carbon dioxide, as replacements in heat pump systems. When operating in a transcritical cycle, carbon dioxide heat pumps are well suited for use in high temperature water heating heat pumps. In this work, four systems are analyzed: with and without the use of a suction line heat exchanger, and two water heating schemes. These two schemes involve the heating of water to its desired temperature at a low water flow rate in a single pass through the heat pump, and the heating of water at a high water flow rate, but requiring multiple passes. The performance and resulting heat exchanger size of these four systems is analyzed through the development of an overall system model. This system model uses component-level models that were developed based upon heat exchanger geometry and subsequently validated through experimental testing on a test facility developed for this purpose.

How do fuel and air mix, if a liquid fuel is injected into an environment featuring pressure and temperature that exceed the critical pressure and the critical temperature of the fuel? It is subject of current discussion on whether and if so when, the fuel/air-mixture becomes supercritical or not. We here report experimental data comprising three mixture properties that are relevant for the current debate, all spatially and temporally resolved throughout the spray and injection event: The overall composition of the fuel/air-mixture, the liquid fraction of the fuel/air-mixture, and the temperature of the liquid phase. To this end, we applied Raman spectroscopy and gave special attention to the signature of the Raman OH-band of ethanol, which we used as fuel. Its signature is connected to the development of a hydrogen bonded network between the ethanol molecules and thus extremely sensitive to thermodynamic state and temperature. Measurements were carried out in a high-pressure, high-temperature combustion vessel in a pressure range of 3−8 MPa and a temperature range of 573−923 K. For the highest set temperature we found ethanol in liquid-like mixtures that exceeded the mixture critical temperature. This is an indication of the existence of a single-phase mixing path.

Supermarkets have a high energy demand where almost half of the energy is used within the refrigeration system. The refrigeration system utilises a cycle where heat is taken and rejected. The rejected heat could be recovered and utilised for other purposes, such as covering internal heating demand or be exported to other facilities. Implementation of heat recovery could create business opportunities between the supermarket and other actors involved. The aim of this thesis was to investigate the potential for heat export from the refrigeration system insupermarkets to neighbours. Case studies were conducted on three different supermarkets in Sweden. This project evaluated field measurements for the current heat recovery within the systems, investigated heat recovery during optimal operation conditions as well as a techno-economic analysis of the heatrecovery system. All three supermarkets within the study recovered heat in the current configuration. In both CG Ytterby and CG Eskilstuna, the recovered heat covered the majority of the internal heating demand. Nevertheless, there was a great potential to recover more heat, since most of the heat was rejected through the gas cooler. The system was also limited by the discharge pressure and the return temperature in the heat recovery unit. The techno-economic analyses indicated that all supermarkets had the potential to cover both internal heating demand with the recovered heat, as well as produce excess to export. It was observed to be more profitable to disconnect from the DHN and become self-sufficient. Heat export from supermarkets would create new innovative business models which can be profitable for both the supermarket and the heat consumer. To produce excess heat, the system had to operate at optimal conditions, increasing electricity usage and hence associated operational costs. This demonstrated the importance of revenues to make it an economically feasible solution. / Livsmedelsbutiker har ett högt energibehov där nästan hälften av energin används i kylsystemet. Kylsystemen använder sig av en cykel där värme tas upp och avges. Den värme som avges kan återvinnas och användas för andra ändamål, till exempel för att täcka internt värmebehov eller exporteras till andra fastigheter och därmed skapa affärsmöjligheter för livsmedelsbutiken. Syftet med examensarbetet var att undersöka potentialen för export av värme från kylsystemet i livsmedelsbutiker. Fallstudier genomfördes för tre olika livsmedelsbutiker i Sverige. Projektet utvärderade fältmätningar för aktuell värmeåtervinning inom systemen, undersökte värmeåtervinning under optimala driftförhållanden samt utförde en teknisk-ekonomisk analys av värmeåtervinningsystemet. Livsmedelsbutikerna i studien återvann värme i den nuvarande konfigurationen. I både CG Ytterby och CG Eskilstuna täckte den återvunna värmen större delen av det interna värmebehovet och det fanns en stor potential att återvinna mer värme, eftersom majoriteten av värmen släpps ut genom gaskylaren. Systemet begränsades även av trycket efter kompressorerna och returtemperaturen i värmeåtervinningsenheten. De teknoekonomiska analyserna visade att alla livsmedelsbutiker hade potential att täcka internt värmebehov med den återvunna värmen, samt producera överskott för export. Det var även observerat att vara mer lönsamt att koppla från fjärrvärmenätverket och bli självförsörjande. Export av värme från livsmedelsbutiker skapar nya innovativa affärsmodeller som kan vara lönsamma för både livsmedelsbutiker och värmekonsumenter. För att producera överskottsvärme var systemet tvunget att drivas under optimala förhållanden, vilket ökade elanvändningen och därmed tillhörande driftskostnader. Detta visade på vikten av intäkter för att göra det till en ekonomiskt genomförbar lösning.

Cette recherche se focalise sur les problèmes d’instabilités de combustion hautes fréquences dans les moteurs fusées. Ces instabilités sont connues pour avoir des effets néfastes et peuvent, dans certains cas, causer la destruction du système propulsif. Pour éviter l’apparition de ces instabilités, il est important de connaître les mécanismes qui entretiennent ces phénomènes dynamiques et de comprendre le couplage complexe entre l’injection, la combustion et la résonnance acoustique du système. Ce travail comprend trois parties.La première partie traite de la simulation numérique de jets non-réactifs et réactifs soumis à différentes conditions de modulation afin de comprendre les interactions entre les jets, les flammes et leur environnement. Les calculs numériques de jets ronds non-réactifs ainsi que des flammes plus complexes formées par des injecteurs coaxiaux dans des conditions transcritiques ont été effectuées avec des simulations aux grandes échelles (SGE), adaptées aux conditions gaz réels à l’aide du solveur AVBP-RG. Les jets ronds ont été soumis à des fluctuations de vitesse transverse. Il a été trouvé que pour toutes les amplitudes et fréquences de modulation, le jet est déformé et oscille dans la direction transverse. Ce comportement peut être représenté par un modèle. Les flammes coaxiales ont été soumises à une modulation de débit et de pression. La modulation induit des variations du dégagement de chaleur global. Un modèle mathématique reliant les paramètres modulés au dégagement de chaleur est proposé.La seconde partie contient les travaux expérimentaux. Dans ce cadre, un nouveau banc expérimental a été développé pour l’étude de cavités couplées pressurisées (NPCC). Le couplage entre le plénum (ou dôme) et la chambre a été étudié. Un modèle reliant les fluctuations de pression et de vitesse en sortie des injecteurs a été développé et comparés aux données d’essais. Le banc NPCC a aussi été utilisé pour acquérir plus de connaissances sur le niveau d’amortissement. Les coefficients d’amortissement ont été déterminés.La dernière partie de ce document traite du développement d’un modèle ordre réduit qui représente des mécanismes qui entretiennent et amortissent les instabilités de combustion hautes fréquences. Cette description dynamique a été incorporée dans un code de stabilité haute fréquence (STAHF). Ce code a été utilisé pour étudier un moteur à ergols liquides d’une puissance de 87 MW (le banc BKD du DLR en Allemagne) qui présente des instabilités hautes fréquences. Après le recalage de certains paramètres de contrôle, STAHF a été capable de retrouver des résultats obtenus d’essais au DLR. / This research concerns some of the issues raised by high frequency combustion instabilities in rocket engines. These instabilities are known to have detrimental effects leading, in some cases, to the destruction of the propulsion system. To avoid the appearance of such instabilities it is important to gain an understanding of the processes driving such dynamical phenomena. One has to consider the complex coupling between injection, combustion and the acoustic resonances of the system. The present work contributes to this objective by developing three items.The first deals with numerical simulations of non-reactive and reactive jets submitted to different modulation conditions to understand the interaction between jets, flames and their environment. Numerical simulations of non-reactive round jets as well as more complex flames formed by coaxial injectors operating under transcritical conditions were carried out using large eddy simulation (LES) adapted to real gas situations by making use of the AVBP-RG flow solver. Round jets were submitted to transverse velocity fluctuations. It has been found that for all amplitudes and frequencies of modulation, the modulated jet is deformed and oscillates. This behavior can be represented by a model. The coaxial flames were submitted to mass flow rate and pressure modulation. For these cases it has been found that the modulation induces variations of the global heat release rate. A mathematical relationship between the modulated parameters and the heat release rate has been proposed.The second item includes experimental investigations. For this purpose a New Pressurized Coupled Cavities (NPCC) laboratory test rig has been developed. The possible coupling between the plenum and the thrust chamber was studied. A model, linking pressure and velocity fluctuations between the plenum and the thrust chamber, has been developed. The laboratory test rig was also used to gather some knowledge on the levels of damping and the damping coefficients could be determined.The last item of this document deals with the development of a reduced order dynamical model which includes some of the driving and damping mechanisms of high frequency combustion instabilities. This dynamical description was implemented in a high frequency stability code (STAHF). This code was used to examine a 87 MW liquid rocket engine (BKD operated at DLR, Germany) exhibiting high frequency oscillations. After the adjustment of some control parameters, STAHF was able to retrieve some the features observed in experiments carried out at DLR.

La pompe à chaleur industrielle très haute température (PAC THT) à compression mécanique de vapeur, fonctionnant à l'électricité, figure parmi l'une des technologies innovantes les plus efficaces permettant de valoriser les rejets thermiques industriels à basse et moyenne température (<90 °C). Néanmoins, compte tenu des besoins industriels actuels de chaleur, les niveaux de température cible atteignable par les PACs restent trop faibles et freinent fortement son implantation. Les procédés de séchage, dans leur grande majorité, rejettent des buées ou de la vapeur d'eau à moyenne température (50 °C-90 °C) et ont des besoins de chaleur à très haute température (110 °C-150 °C). Le grand écart de température entre la source et le besoin de chaleur ainsi que le niveau de température du besoin, font qu'aujourd'hui envisager l'intégration d'une PAC dans ce type de procédés relève d'un défi énergétique et technologique particulièrement intéressant, dont l'enjeu économique est considérable. Les présents travaux de recherche envisagent à l'aide d'une méthodologie générique d'optimisation de cycles thermodynamiques basée sur la minimisation de la production d'entropie dans les échangeurs de chaleur de déceler les architectures de PACs les plus efficaces d'un point de vue énergétique. L'analyse théorique a permis de déceler la haute efficacité énergétique des architectures transcritiques de PACs dans des conditions de grands glissements de température entre l'entrée et la sortie du besoin de chaleur. Le développement d'un démonstrateur de PAC transcritique très haute température fonctionnant au R32 (PAC T-THT R32) a permis d'une part de démontrer la faisabilité technique d'une PAC, pouvant atteindre la température cible de 120 °C en partant de 60 °C avec une source de chaleur disponible à 50 °C, et d'autres part de démontrer sa haute efficacité énergétique (COP = 4). / The mechanical vapour compression high temperature heat pump for industry using electricity is one of the most effective innovative technologies to recover the industrial waste heat at low and medium temperature (<90°C). However, given the current industrial heat needs, the heat pump target temperature levels remain too low and slow strongly its implantation. Overwhelmingly, the drying processes reject saturated moist air at middle temperature (50°C-90°C) and have heat needs at very high temperature (110°C-150°C). The large temperature difference between the source and the heat need and the level off temperature that is needed, today, makes the heat pump integration in such processes an interesting energy and technological challenge, whose economic stake is considerable. The present works tackle, with a generic methodology of thermodynamic optimisation cycles based on the entropy minimization in the heat exchangers, to identify the most efficiency heat pump architectures from an energy point of view. The theoretical analysis allowed to detect the transcritical heat pump architecture, in conditions of high temperature glides between the inlet and the outlet of the heat need. The development of a transcritical high temperature heat pump demonstrator using the R32 as working fluid allowed to demonstrate the technical feasibility of a heat pump that can reach the target temperature of 120°C from 60°C with an available heat source at 50°C, and to demonstrate its high energy efficiency (COP = 4).

Wie vermischen sich Kraftstoff und Luft, wenn ein flüssiger Kraftstoff in einer Umgebung eingespritzt und zerstäubt wird, deren Parameter Druck und Temperatur den kritischen Druck und die kritische Temperatur des Kraftstoffs überschreiten? In dieser Arbeit wurden Experimente basierend auf Raman-spektoskopischen Methoden zur Gemischbildung unter eben solchen Bedingungen durchgeführt. Ziel der Arbeit war der experimentelle Nachweis der Möglichkeit einphasiger Gemischbildung, d.h. des Übergangs von eingespritztem Kraftstoff in das überkritische Regime, und von da Mischung mit der umgebenden initial überkritischen Stickstoffphase ohne Auftreten von Phasengrenzen. Dazu war es nötig, das Zweiphasengebiet der eingesetzten Stoffe exakt zu charakterisieren (die Gas-Flüssig-Gleichgewichte zu messen), und die Temperatur der Flüssigphase zuverlässig während der Gemischbildung zu messen. Mittels eines Mikrokapillar-Aufbaus wurden Daten zu Gas-Flüssig-Gleichgewichten (engl. Vapor-liquid-equilibria, VLE) bei hohen Drücken und Temperaturen erhoben. Dazu wurden unter kontrollierten Bedingungen phasenspezifische Raman-Spektren der Gas- und der Flüssigphase gemessen, aus denen sich in-situ die Gemischzusammensetzung der Phasen ermitteln ließ. Desweiteren wurden Methoden zur Bestimmung der Temperatur der Flüssigphase erarbeitet, sowie eine Methode zur Unterscheidung von Gas- und Flüssiganteil anhand der Raman-Spektren. Die letzten Methoden basieren auf einer Auswertung des Signals der Hydroxyl-Gruppe von Ethanol, welches in der vorliegenden Arbeit als Kraftstoff-Surrogat verwendet wurde. Danach wurden diese Methoden in einer Hochdruck-Hochtemperatur-Einspritzkammer eingesetzt. Hier wurde Kraftstoff unter realistischen Motorbedingungen eingespritzt, und Raman-Spektroskopie zeitlich und örtlich aufgelöst im entstehenden Spray angewandt. Dies erlaubte die Untersuchung der Gemischbildung ohne Beeinträchtigung des Systems, wie etwa durch Zugabe von Marker-Stoffen oder den Einsatz invasiver Messtechniken. Die gewonnenen VLE-Daten stellen eine erhebliche Verbesserung der Datengrundlage in diesem Druck- und Temperaturbereich dar, da Literaturdaten hier rar sind. Der realisierte Mikrokapillar-Aufbau benötigt nur minimale Volumina an Flüssigkeit und Gas, und lässt vielfältige weitere Einsatzmöglichkeiten wie etwa die Messung von VLE-Daten anderer Stoffe oder auch ternärer Gemische, oder die Untersuchung chemischer Reaktionen zu. Gleichgewichte stellen sich aufgrund des hohen Oberflächen-Volumen-Verhältnisses und der insgesamt kurzen Weglängen schnell ein. Die Zuverlässigkeit der gewonnenen Daten konnte durch Vergleich mit den wenigen vorhandenen Literaturdaten gezeigt werden. Bei Vorliegen von Wasserstoffbrückenbindungen konnte die Zuverlässigkeit und Überlegenheit der Raman-Thermometrie basierend auf der „integrated absolute difference spectroscopy“ gezeigt werden, außerdem erlaubt das charakteristische Raman-Signal der Hydroxyl-Gruppe in Wasserstoff-brückenbindung eine Unterscheidung von Gas- und Flüssigphase in überlagerten Spektren. Zum Nachweis der Durchführbarkeit einer solchen Unterscheidung wurde eine Methode entwickelt, um mittels unterschiedlicher Trigger-Signale phasenspezifische Messungen ohne Überlagerung durch eine alternierende Phase durchzuführen. Die gemessenen, örtlich und zeitlich aufgelösten Daten zur Gemischbildung im Spray erlauben die thermodynamische Charakterisierung der Gemischbildung anhand der ermittelten Parameter „globale Gemischzusammensetzung“, „Flüssigphasenanteil“ und „Flüssigphasentemperatur“. Die Ergebnisse zeigten für hohe Umgebungsdrücke und Temperaturen, dass die Flüssigphase Temperaturen jenseits ihrer kritischen Temperatur erreichen kann. Dies lieferte den Nachweis des Auftretens einphasiger Gemischbildung.:I Abbreviations and symbols II Figures III Tables 1. Introduction 2. State of the art 2.1.1. Objective of this thesis 3. Application-oriented fundamentals 3.1. Thermodynamic states 3.1.1. Single-component systems 3.1.2. Multi-compound systems 3.2. Micro-fluidic systems 3.3. Spray break-up 3.4. Raman spectroscopy 3.4.1. Fundamentals 3.4.2. Quantifiability of Raman signals 3.4.3. Liquid fraction determination 3.4.4. Raman thermometry 4. Vapor-Liquid-Equilibra – Experimental setup 4.1. Overview and auxiliary equipment 4.2. Heating system 4.3. Raman probe 4.4. Light guard technique 4.5. Materials and Experiments 5. Vapor-Liquid-Equilibria – Results and discussion 5.1. Data evaluation 5.2. Calibration 5.3. Liquid film correction 5.4. Results ethanol/nitrogen 5.5. Results decane/nitrogen 5.6. Raman thermometry 6. Sprays – Experimental Setup 6.1. Overview and auxiliary equipment 6.2. Calibration setup 6.3. Spray excitation and detection 6.4. Investigated conditions 7. Sprays – Results and discussion 7.1. Data evaluation 7.1.1. Fuel fraction determination 7.1.2. Liquid fraction determination 7.1.3. Liquid temperature determination 7.2. Calibration results 7.3. Spray results 8. Conclusion 9. References / How do fuel and air mix, when liquid fuel is injected and atomized in an environment with parameters pressure and temperature exceeding the respective critical ones of the fuel? In this work, experiments on mixture formation at such conditions based on methods of Raman spectroscopy were performed. Objective of the work was the experimental proof of single-phase mixing, i.e. the transition of injected fuel into the supercritical regime, and therein mixture with the surrounding initially supercritical nitrogen atmosphere without the formation of phase boundaries. To this end, the characterization of the two-phase regime was necessary (i.e. the measurement of the vapor-liquid-equlibria), and the reliable determination of the temperature of the liquid phase during mixture formation. Data on vapor-liquid-equilibria (VLE) were measured in a micro-capillary setup at high temperatures and pressures. To this end, phase-specific Raman spectra of the liquid and the vapor phase were measured at well-controlled conditions, from which the mixture composition of the respective phases was derived in-situ. Furthermore, Methods for the determination of the liquid phase temperature were developed, as well as an approach for the differentiation of the liquid phase signal from the vapor phase signal. The two latter methods exploit the specific signal of the hydroxyl-group of ethanol, which served as a fuel surrogate in this work. In the next step, these methods were applied in a high pressure, high temperature injection chamber. Here, fuel was injected at realistic engine-like conditions, and Raman spectroscopy was applied temporally and spatially resolved across the created spray cone. This approach allowed the Investigation of the mixture formation without affecting the system, compared to e.g. the addition of markers or the use of invasive measurement techniques. The gathered data are a significant addition to the scarce data base available in this pressure and temperature range. The realized micro-capillary setup needs only minimal volume of fluids, and allows various other operational Scenarios like the measurement of VLE data of other components, binary or ternary, or the Investigation of chemical reactions. Equilibria form very fast due to the high surface-to-volume ratio and the short path lenghts. The reliability of the gathered data were shown by comparison with literature. With the presence of hydrogen bonds, the reliability and superiority of the Raman thermometry based on the 'integrated absolute difference spectroscopy' was shown. Furthermore, the characteristic Raman signal of the hydroxyl-group allows for the differentiation of the vapor- and liquid-phase contributions in superimposed spectra from vapor- and liquid-phase. For the proof of feasibility of such a differentiation, a sophisticated method for the phase-specific measurements was developed by exploiting distinctive trigger Signals from the phases, allowing measurements in one phase without cross-talk from the alternating phase. The temporally and spatially resolved data measured during mixture formation in the spray lead to the thermodynamic characterization of the mixture formation with respect to the Parameters 'global mixture composition', 'liquid phase fraction', and 'liquid phase temperature'. The results for high pressures and temperatures inside the chamber show that the liquid or liquid-like phase can reach temperatures exceeding the critical temperature of the fuel. This provides the proof a the existance of single-phase mixing.:I Abbreviations and symbols II Figures III Tables 1. Introduction 2. State of the art 2.1.1. Objective of this thesis 3. Application-oriented fundamentals 3.1. Thermodynamic states 3.1.1. Single-component systems 3.1.2. Multi-compound systems 3.2. Micro-fluidic systems 3.3. Spray break-up 3.4. Raman spectroscopy 3.4.1. Fundamentals 3.4.2. Quantifiability of Raman signals 3.4.3. Liquid fraction determination 3.4.4. Raman thermometry 4. Vapor-Liquid-Equilibra – Experimental setup 4.1. Overview and auxiliary equipment 4.2. Heating system 4.3. Raman probe 4.4. Light guard technique 4.5. Materials and Experiments 5. Vapor-Liquid-Equilibria – Results and discussion 5.1. Data evaluation 5.2. Calibration 5.3. Liquid film correction 5.4. Results ethanol/nitrogen 5.5. Results decane/nitrogen 5.6. Raman thermometry 6. Sprays – Experimental Setup 6.1. Overview and auxiliary equipment 6.2. Calibration setup 6.3. Spray excitation and detection 6.4. Investigated conditions 7. Sprays – Results and discussion 7.1. Data evaluation 7.1.1. Fuel fraction determination 7.1.2. Liquid fraction determination 7.1.3. Liquid temperature determination 7.2. Calibration results 7.3. Spray results 8. Conclusion 9. References