The aim of this thesis is to evaluate ORC systems and technologies from an energy and economic perspective. ORC systems are a growing renewable electricity generation technology, but New Zealand has limited local skills and expertise for identifying ORC resource opportunities and subsequently developing suitable technologies at low cost. For this reason, this thesis researches ORC technology, resource types, and international development, with the aim to determine guidelines for how to cost-effectively develop ORC systems, and to make recommendations applicable to furthering their development within a New Zealand context. This thesis first uses two surveys, one of commercial ORC installations, and a second of economic evaluations of ORC systems in literature, to determine what resources and economic scenarios are supportive of commercial development. It is found that geothermal resources provide the largest share of ORC capacity, with biomass and waste-heat recovery (WHR) being developed more recently. The surveys also found that countries with high electricity prices or policy interventions have developed a wider range of resources using ORC systems. This thesis then undertakes an EROI evaluation of ORC electricity generation systems using a combination of top-down and process based methodologies. Various heat sources; geothermal, biomass, solar, and waste heat are evaluated in order to determine how the utilised resource can affect energy profitability. A wide range of EROIstnd values, from 3.4 – 22.7 are found, with solar resources offering the lowest EROIs, and geothermal systems the highest. Higher still EROI values are found to be obtainable with longer system lifetimes, especially for WHR systems. Specific engineering aspects of ORC design and technology such as high-side pressure, heat storage, modularity, superheating, pinch-point temperature difference, and turbine efficiency are evaluated in terms of economic performance, and a variety of general conclusions are made about each. It is found that total system thermo-economic optimisation may not lead to the highest possible EROI, depending on the objective function. Lastly, the effects of past and potential future changes to the markets and economies surrounding ORCs are explored, including the New Zealand electricity spot price, steel and aluminium prices, subsidies, and climate policy. Of the subsidy types explored, it is found that directly subsidising ORC system capital has the greatest effect on the economic performance of ORC systems, as measured by common metrics. In conclusion, this thesis finds that ORC systems have a limited applicability to New Zealand’s electricity market under current economic conditions outside of geothermal and off-grid generation, but changes to these conditions could potentially make their development more viable. The author recommends that favourable resources should be developed using systems that provide high efficiencies, beyond what might provide the best economic performance, in order to increase EROI, and reduce the future need for costly investments into increasingly less favourable resources.

The aim of this thesis is to evaluate ORC systems and technologies from an energy and economic perspective. ORC systems are a growing renewable electricity generation technology, but New Zealand has limited local skills and expertise for identifying ORC resource opportunities and subsequently developing suitable technologies at low cost. For this reason, this thesis researches ORC technology, resource types, and international development, with the aim to determine guidelines for how to cost-effectively develop ORC systems, and to make recommendations applicable to furthering their development within a New Zealand context. This thesis first uses two surveys, one of commercial ORC installations, and a second of economic evaluations of ORC systems in literature, to determine what resources and economic scenarios are supportive of commercial development. It is found that geothermal resources provide the largest share of ORC capacity, with biomass and waste-heat recovery (WHR) being developed more recently. The surveys also found that countries with high electricity prices or policy interventions have developed a wider range of resources using ORC systems. This thesis then undertakes an EROI evaluation of ORC electricity generation systems using a combination of top-down and process based methodologies. Various heat sources; geothermal, biomass, solar, and waste heat are evaluated in order to determine how the utilised resource can affect energy profitability. A wide range of EROIstnd values, from 3.4 – 22.7 are found, with solar resources offering the lowest EROIs, and geothermal systems the highest. Higher still EROI values are found to be obtainable with longer system lifetimes, especially for WHR systems. Specific engineering aspects of ORC design and technology such as high-side pressure, heat storage, modularity, superheating, pinch-point temperature difference, and turbine efficiency are evaluated in terms of economic performance, and a variety of general conclusions are made about each. It is found that total system thermo-economic optimisation may not lead to the highest possible EROI, depending on the objective function. Lastly, the effects of past and potential future changes to the markets and economies surrounding ORCs are explored, including the New Zealand electricity spot price, steel and aluminium prices, subsidies, and climate policy. Of the subsidy types explored, it is found that directly subsidising ORC system capital has the greatest effect on the economic performance of ORC systems, as measured by common metrics. In conclusion, this thesis finds that ORC systems have a limited applicability to New Zealand’s electricity market under current economic conditions outside of geothermal and off-grid generation, but changes to these conditions could potentially make their development more viable. The author recommends that favourable resources should be developed using systems that provide high efficiencies, beyond what might provide the best economic performance, in order to increase EROI, and reduce the future need for costly investments into increasingly less favourable resources.

Cette étude concerne la compréhension des mécanismes de transfert de chaleur et le développement d’un système de stockage pour la valorisation de la chaleur fatale industrielle. L’utilisation de Matériaux à Changement de Phase (MCP) permet d’atteindre une densité énergétique élevée et de restituer la chaleur à température constante. Cependant, leur faible conductivité thermique impose d’améliorer les transferts thermiques, notamment par l’utilisation d’échangeurs à surface augmentée. Le but est de comprendre le comportement de tels échangeurs en régime transitoire au contact de MCP. Une étude expérimentale à basse température, où quatre échangeurs de type tube-calandre ont été testés avec différentes orientations (horizontale/verticale) et injections (haut/bas), a mis en évidence des phénomènes de transfert thermique importants, comme la convection naturelle à la charge et la contraction volumique à la décharge. Ces observations ont été validées par un modèle CFD tridimensionnel. Une méthode de comparaison des performances basée sur un calcul d’énergie par le biais d’un maillage expérimental est proposée et permet de sélectionner un échangeur selon les critères de densités énergétiques, de temps caractéristique et de coût. Trois MCP, envisagés pour l’application, ont alors été testés à température réelle (100-200 °C) au contact d’un échangeur tube inox à ailettes transverses en aluminium pour évaluer leur cyclabilité et comparer leur comportement. Le mélange de sels, H105 (Tfusion = 122 °C), n’est pas retenu pour l’application à cause de sa faible densité énergétique (≈ 56 kWh/m3) et sa plage de fusion trop étalée. L’acide sébacique (Tfusion = 132 °C) a un comportement répétable au cours des cycles et une densité énergétique plus élevée (≈ 66 kWh/m3). L’alcool de sucre, l’érythritol (Tfusion = 118 °C), présente de bonnes thermo-physiques (128 kWh/m3) mais la maîtrise de sa cristallisation est un point clé pour l’utiliser en tant que MCP. / This PhD thesis deals with the understanding of the heat transfer mechanisms and with the development of thermal energy storage system for the industrial waste heat recovery application. The use of Phase Change Materials (PCM) is attractive for its high storage density and its possibility to deliver heat at constant temperature. However, the PCM low thermal conductivity leads to develop heat transfer improvement methods, such as heat exchangers with increased heat transfer surface. The goal is to characterize the behavior of such heat exchangers An experimental study, where four several heat exchangers have been tested with different orientations (horizontal/vertical) and injection types (upward/downward), highlighted the impact of natural convection during the melting process and the volume contraction one during the solidification. These results have been validated through a 3D numerical model. A performance comparison method based on an energy calculation through an experimental mesh is proposed and enables to select a heat exchanger on criteria such as the storage density, the characteristic time and the cost. Three PCM, adapted to our application, have been tested at the intended temperature (100-200 °C) by integrating them into a storage system made of a stainless steel tube with aluminum circular fins. Their ability to resist to repeated cycles has been assessed and their behavior has been compared. The salts mixture, H105 (Tmelting = 122 °C), is not selected for the application because of it low storage density (≈ 56 kWh/m3) and its large melting area. The sebacic acid (Tmelting = 132 °C) has a repeatable behavior with cycles and a higher storage density (≈ 66 kWh/m3) and is appropriate as storage material. The sugar alcohol, erythritol (Tmelting = 118 °C), has good thermo-physical properties (128 kWh/m3) but the crystallization control is a key point to use it as a PCM.

Organic Rankine cycles can be integrated with district heating systems and in applications of biogas digestion. Evaluating the performance of the installations by Againity AB in Ronneby and Norrköping, Sweden, is a unique opportunity which can support the establishment of ORC technology in the waste heat recovery market, unveiling its feasibilities and limitations. Operational data gathered from October 2017 until April 2018, provides this thesis with information about the ORC-systems. A method using Coolprop and Matlab has been used to detect steady-state series in the Ronneby installation using moving standard deviation and inclination criteria. By screening the data and selecting these series, analytical equations can be used to determine the performance of the installations and map the linear relationship between variables like pressure and generator power. The largest impact on the system in Ronneby is developed in the condenser. Large coolant volume flow creates large heat sink capacity and higher generator efficiency and power. However, with increasing generator power the condenser pressure decrease. Lower condenser pressure results in a decreased evaporation pressure, which could be maintained if the pump was able to run at higher frequencies. The Plant in Norrköping needs further studies and a review of its sensors. The code in Matlab is a resource to Againity and Linköpings university for future work in performance evaluation. It can be used to detect errors in energy balance, local readings, and picture the machines' performance graphically.

Cette étude est motivée par la protection de l'environnement et la réduction des émissions de CO2 émis par les moteurs à combustion interne. L'objectif de la thèse est d'étudier les possibilités de la réduction de la consommation de carburant d'un moteur diesel d’automobile grâce à la récupération de la chaleur des gaz d'échappement basée sur un cycle de Rankine. Afin de déterminer l'énergie perdue, le moteur a été testé sur un banc d’essais et les paramètres des gaz d’échappement ont été mesurés. Un modèle de simulation du moteur a également été développé et validé grâce aux résultats expérimentaux. Le potentiel de récupération de chaleur sur les gaz d’échappement et sur le refroidissement a été estimé. Cette analyse a révélé que le potentiel sur les gaz d’échappement est plus élevé que celui sur le refroidissement. Grâce au modèle numérique et aux essais, la puissance et l'efficacité du cycle de Rankine ont été étudiées. Enfin, l'impact du système de récupération d’énergie sur les performances du moteur a été analysé. Les résultats montrent que la puissance du moteur augmente de 4,3% au point de puissance maximale du moteur. / This study is motivated by the environment protection and the reduction of emissions CO2 from internal combustion engines. The aim of the thesis is to study the possibilities of fuel consumption reduction of a diesel engine intended for a passenger car by means of waste heat recovery from exhaust gases based on thermodynamic cycle (Rankine cycle). In order to determine the waste heat, the engine was tested on a test bench as the exhaust parameters were measured. A simulation model of the engine has also been developed and validated by means of experimental results. The recovery potential of the exhaust gases and the cooling system has been estimated. This analysis revealed that the waste heat recovery potential of the exhaust gases is higher that the cooling sys-tem. By means of Rankine cycle numerical model and experimental test, the output power and efficiency of the Rankine cycle were studied. Finally, the impact of the heat recovery system on engine performance was studied. The results revealed that the engine power increases by 4.3% at the operating point which corresponds to the maximum engine power. / Това изследване е мотивирано от опазването на околната среда и намаляването на емисиите на CO2 от двигателите с вътрешно горене. Целта на дисертацията е да проучи възможнос-тите за намаляване на разхода на гориво на дизелов двигател, предназначен за лек автомо-бил, чрез рекупериране на енергия с цикъл на Ранкин. За да се определи неоползотворената енергия в отработилите газове бе използван изпитателен стенд. Симулационен модел на двигателя е разработен и валидиран чрез експерименталните резултати. Направена е оценка на потенциала за рекупериране на енергия от отработилите газове и охладителната система. Този анализ показва, че потенциала за рекупериране е по-голям в изпускателната система. С помощта на експериментален стенд и числен модел на цикъла на Ранкин са установени мощността и ефективността на системата. Въздействието на системата за рекупериране на енергия е изследвано. Данните показват, че мощността на двигателя се увеличава с до 4,3%.

L’évolution croissante du prix des carburants ainsi que les normes antipollution de plus en plus drastiques obligent les fabricants de véhicules commerciaux à développer des solutions innovantes pour réduire la consommation de carburant. Dans cet objectif, comme une grande partie de l’énergie contenue dans le carburant est directement relâchée à l’ambient sous forme de chaleur, celle-ci peut être valorisée et transformée via un cycle thermodynamique secondaire. Dans ce cadre, l’importante utilisation du cycle de Rankine à travers le monde en font un candidat naturel pour une implémentation dans un véhicule. Mais contrairement à une utilisation stationnaire, de nombreux obstacles se dressent pour une intégration totale dans un poids lourd. De nombreuses études ont été menées ces trente dernières années afin de déterminer le potentiel réel d’un tel système une fois embarqué à bord d’un véhicule. Les nombreuses sources de chaleur valorisables, les contraintes inhérentes à l’application embarquée ou encore les forts régimes transitoires induits par l’utilisation du camion doivent mener à une optimisation à la fois de l’architecture du système ainsi que de son système de contrôle. L’optimisation du système mène à un choix en terme de sources chaudes et froides, de topologie, de fluide de travail ainsi que de dimensionnement des composants afin de maximiser les performances. Le système de contrôle joue lui un rôle primordial afin de tirer un bénéfice maximum d’un tel système connaissant ses limites physiques ainsi que d’assurer une utilisation efficace. Dans cette thèse, une méthodologie de conception d’un système de valorisation des rejets thermiques est proposée. En se basant sur des simulations du véhicule complet basées sur un modèle détaillé, les thématiques de la sélection du fluide de travail, des sources chaudes et froides ainsi que l’optimisation des composants et du cycle sont approchées. Par la suite, le problème de contrôle en ligne de la surchauffe à la sortie de l’évaporateur est formalisé. En tenant compte des contraintes numériques d’implémentation, différentes stratégies de commande sont mises en place, allant du contrôleur PID à des structures plus avancées telle que la commande prédictive par modèle ou une loi de commande basée sur un observateur. La plupart de ces stratégies sont validées expérimentalement sur un banc d’essai mis en place durant la thèse / The constant evolution of oil prices and the more and more stringent automotive emission standards force the original engine manufacturers to search for innovative solutions in order to reduce oil consumption. As an important part of the energy contained in the primary carrier (the fuel) is lost to the ambient through heat, it seems convenient to recover a part of this thermal energy and to turn it into fuel consumption reduction. Thermodynamic bottoming cycle such as the Rankine cycle could be used to meet this objective. Its popular use throughout the world for electricity generation makes it a natural candidate for on-board implementation in vehicles. However, a certain number of hurdles are still present before the system can be efficiently applied to heavy-duty trucks. In the last thirty years, numerous studies heave been carried out to evaluate the real potential of that kind of system on a vehicle but nothing has yet been commercialized. The heat sources to recover from, the constraints relative to the on-board application and the long and frequent transient behavior of the vehicle mean both the system architecture and its control strategy need to be optimized. The system optimization leads to a choice in terms of working fluid, heat sources and sinks, and components sizing in order to maximize power recovery and hence the fuel saving. The control plays a major role by using the capability of such a system to ensure an efficient and safe operation and limiting the interactions with the other vehicle sub-systems. In this thesis, a system design methodology is introduced to optimize the system architecture using complete model-based vehicle simulation. The constraints relative to the mobile application are taken into consideration to evaluate the potential of such a system. Modelbased control strategies for on controlled variable, namely the superheat level, are developed. Constrained by the implementation platform, different control frameworks ranging from PID to model predictive controllers or observer based controllers are developed to fit into a normal automotive electronic control unit. Most of these novel strategies were experimentally validated on a test rig developed during the thesis

Exploitation of waste heat could achieve economic and environmental benefits, while at the same time increase energy efficiency in process sites. Diverse commercialised technologies exist to recover useful energy from waste heat. In addition, there are multiple on-site and offsite end-uses of recovered energy. The challenge is to find the optimal mix of technologies and end-uses of recovered energy taking into account the quantity and quality of waste heat sources, interactions with interconnected systems and constraints on capital investment. Explicit models for waste heat recovery technologies that are easily embedded within appropriate process synthesis frameworks are proposed in this work. A novel screening tool is also proposed to guide selection of technology options. The screening tool considers the deviation of the actual performance from the ideal performance of technologies, where the actual performance takes into account irreversibilities due to finite temperature heat transfer. Results from applying the screening tool show that better temperature matching between heat sources and technologies reduces the energy quality degradation during the conversion process. A ranking criterion is also proposed to evaluate end-uses of recovered energy. Applying the ranking criterion shows the use to which energy recovered from waste heat is put determines the economics and potential to reduce CO2 emissions when waste heat recovery is integrated in process sites. This thesis also proposes a novel methodological framework based on graphical and optimization techniques to integrate waste heat recovery into existing process sites. The graphical techniques are shown to provide useful insights into the features of a good solution and assess the potential in industrial waste heat prior to detailed design. The optimization model allows systematic selection and combination of waste heat source streams, selection of technology options, technology working fluids, and exploitation of interactions with interconnected systems. The optimization problem is formulated as a Mixed Integer Linear Program, solved using the branch-and-bound algorithm. The objective is to maximize the economic potential considering capital investment, maintenance costs and operating costs of the selected waste heat recovery technologies. The methodology is applied to industrial case studies. Results indicate that combining waste heat recovery options yield additional increases in efficiency, reductions in CO2 emissions and costs. The case study also demonstrates that significant benefits from waste heat utilization can be achieved when interactions with interconnected systems are considered simultaneously. The thesis shows that the methodology has potential to identify, screen, select and combine waste heat recovery options for process sites. Results suggest that recovery of waste heat can improve the energy security of process sites and global energy security through the conservation of fuel and reduction in CO2 emissions and costs. The methodological framework can inform integration of waste heat recovery in the process industries and formulation of public policies on industrial waste heat utilization.

Ce travail de thèse concerne l’étude de la faisabilité des cycles organiques sous-critiques et supercritiques de Rankine pour la valorisation de rejets thermiques industriels à basse température. Dans un premier temps, un état de l’art des cycles ORC (acronyme anglais pour Organic Rankine Cycle) et leurs fluides de travail a été réalisé. Nous avons réalisé une comparaison préliminaire de plusieurs configurations à partir de la littérature scientifique. Dans un second temps, les méthodes d’analyse énergétique et exergétique ont été appliquées pour évaluer et optimiser les performances des cycles ORC. En effet, la seule méthode d’analyse énergétique n’est pas suffisante pour juger de la bonne utilisation du potentiel énergétique de la source de chaleur disponible correspondant à un rejet industrielle de chaleur (chaleur fatale). L’analyse exergétique, intervient en complément de l’analyse énergétique du système, afin de permettre de localiser les pertes des ressources énergétiques dans les différentes composantes du système et de déterminer leurs importances relatives et leurs causes. Une optimisation thermo-économique des installations de valorisation de rejets thermiques utilisant un cycle sous-critique ou supercritique de Rankine a été effectuée. Nos résultats montrent que la valorisation de rejets thermiques industriels à basse température (ex. source thermique de 150 °C) en utilisant un cycle ORC sous-critique est plus intéressante sur le plan énergétique que celle opérée en utilisant un cycle supercritique de Rankine. / This thesis concerns the feasibility study of subcritical and supercritical organic Rankine cycles for industrial waste heat recovery at relatively low temperature. Initially, a state of the art of ORCs (Organic Rankine Cycles) and their working fluids has been achieved. We conducted a preliminary comparison of several configurations from the scientific literature. In a second step, methods of energy and exergy analysis were applied to evaluate and optimize the performance of the ORCs. Indeed, sole energy analysis is not enough to access the proper use of the energy potential of the available heat source that corresponds to an industrial waste heat. Exergy analysis, in a complementary way to the energy analysis, enables us to locate the energy resources losses in the various components of the system and to determine their true magnitude and their causes. A thermo-economic optimization of waste heat recovery systems using a subcritical or supercritical Rankine cycle has been performed. According to the results, the industrial waste heat recovery at low temperature (e.g. heat source 150 ° C) using a subcritical ORC is more interesting on economic point of view than the system using a supercritical Rankine cycle

The use of gas microturbines as a primary unit in CHP is still weak in the industrial process. It gives the driving force to the main aim of this master thesis, which is the technical and economic evaluation of the gas microturbines waste heat recovery system, which is the key factor for their economic sustainability. Assignment contains description of CHP system that was gradually built in LENP laboratory, part of NETME Centre. The author has joined the final work before start-up of the CHP system. He presents and describes results of the first experiments on this unit. The flue gas of a microturbine was used for heating water by heat exchanger flue gas–water and for direct linen drying. The case study of laundry with capacity 10 tons per shift was developed in cooperation with companies in laundry care. Results of those tests were used to process integration and utilization of this professional industrial laundry All obstacles found and opportunities of the use of microturbines are comprehensively described and tested in case studies, which are simulated in Chemstation Chemcad Software. Results of the thesis are expected to be useful these fields: the use of gas microturbines in industry & energy savings in industrial laundries.

The thesis deals with the refrigeration systems. It analyzes ways to optimize the refrigeration process and the associated energy savings. In a practical application on an industrial building where there is the need of cooling the machinery, it compares the reference system with another two optimized alternatives. The heat recovery alternative supports heating and hot water supply and the water-side free cooling alternative lowers the energy consumption during the cold period of the year. The experimental section assesses the suitability of floor cooling in relation to the stratification of air temperature along the height of the room and the effect on thermal comfort of people.