B. Boltyansky Operation of the heat and power complex Alatyr to power Russian oil and gas facilities, Master's Dissertation, 2017 - 102 pages, 26 tables, 30 figures Supervisor Prof. V. G. Kucherov, Doctor of Sciences, Department of Energy Technology. The work includes the following. A calculation of the main thermodynamic cycle of the heat and power complex Alatyr heat and power complex. A consideration of various schemes of using the Rankine organic cycle WERE integrated in the Alatyr heat and power complex with the aim of increasing energy efficiency. Conclusions about the feasibility of using the heat and power complex Alatyr. Conclusions about the feasibility of integration of the organic Rankine cycle. Economic comparison of the heat and power complex Alatyr with similar facilities on the distributed power generation market. Economic analysis of the comparison of energy blocks of HPC Alatyr with similar designs from other countries. / B. Boltyansky Drift av värme- och kraftkomplexet Alatyr till makten Ryska olje- och gasanläggningar, Masters uppläggning, 2017 - 102 sidor, 26 tabeller, 30 figurer Handledare Prof. VG Kucherov, doktorsexamen, kandidatexamen för teknisk vetenskap, institutionen för termodynamik och termisk motorer. Arbetet innehåller följande. En beräkning av värmekraftkomplexets värmeoch kraftkomplex Alatyrs värmekomplex. En övervägning av olika system för användning av Rankine organiska cykeln var integrerad i Alatyr värme- och kraftkomplexet i syfte att öka energieffektiviteten. Slutsatser om möjligheten att använda värme- och kraftkomplexet Alatyr. Slutsatser om möjligheten att integrera den organiska Rankine-cykeln. Ekonomisk jämförelse av värme- och kraftkomplexet Alatyr med liknande anläggningar på den distribuerade kraftproduktionsmarknaden. Ekonomisk analys av jämförelsen av energiblock av HPC Alatyr med liknande konstruktioner från andra länder.

Many industrial processes have low-temperature waste heat sources that cannot be efficiently recovered. Low grade waste heat has generally been discarded by industry and has become an environmental concern because of thermal pollution. This has led to the lookout for technologies which not only reduce the burden on the non-renewable sources of energy but also take steps toward a cleaner environment. One approach which is found to be highly effective in addressing the above mentioned issues is the Organic Rankine Cycle (ORC), which can make use of low- temperature waste heat to generate electric power. Similar in principle to the conventional cycle, ORC is found to be superior performance-wise because of the organic working fluids used in the cycle. The focus of this study is to examine the ORC using different types of organic fluids and cycle configurations. These organic working fluids were selected to evaluate the effect of the fluid boiling point temperature and the fluid classification on the performance of ORCs. The results are compared with those of water under similar conditions. In order to improve the cycle performance, modified ORCs are also investigated. Regenerative ORCs are analyzed and compared with the basic ORC in order to determine the configuration that presents the best thermal efficiency with minimum irreversibility. The evaluation for both configurations is performed using a combined first and second law analysis by varying certain system operating parameters at various reference temperatures and pressures. A unique approach known as topological method is also used to analyze the system from the exergy point of view. Effects of various components are studied using the exergy-wheel diagram. The results show that ORCs using R113 as working fluid have the best thermal efficiency, while those using Propane demonstrate the worse efficiency. In addition, results from these analyses demonstrate that regenerative ORCs produce higher efficiencies compared to the basic ORC. Furthermore, the regenerative ORC requires less waste heat to produce the same electric power with a lower irreversibility.

Our society is becoming more and more electrified every day. However, a significant portion of the world’s electricity generation relies on the combustion of fossil fuels to produce heat, which is subsequently harnessed to generate electricity. One way of generating electricity from heat is by utilizing a Rankine cycle. The basis of a Rankine cycle is to heat a liquid to its boiling point, which causes an increase in pressure that is used to spin a turbine and a generator. Many industries, such as transportation and manufacturing, produce large amounts of waste heat that needs to be removed from the main process. A Rankine cycle variant called an organic Rankine cycle can be used in a heat power system to generate electricity from lower-temperature waste heat, which increases efficiency since less heat is wasted. This thesis focuses on constructing a dynamic model of Climeon’s heat power system called HP300. The HP300 utilizes an organic Rankine cycle to generate electricity. Dynamic modeling is valuable because it provides a deeper understanding of the system, which is beneficial for its development and improvement. Moreover, a system model has the potential to enhance the system’s performance by using advanced control methods. The HP300 consists of four main components: a pump, a turbine, an evaporator, and a condenser. Each component will be modeled individually, and the complete model will be constructed by combining the component models. Additionally, an in-depth investigation of an advanced modeling method for heat exchangers is to be conducted. The constructed model in this thesis has an average error of 4%. The pump and turbine were modeled as steady-state models, and the evaporator and condenser were modeled with data-driven state-space models. The most important output of the model is the power generated by the turbine. The power was modeled with an average error of 6%. The turbine model performs best for pressure ratios of 1.75 and above. The model for the condenser had larger errors than the evaporator since it had fewer input variables. Improving the model of the condenser would decrease the overall errors of the model. / Vårt samhälle blir mer och mer elektrifierat för varje dag som går. En betydande del av världens elproduktion är dock beroende av förbränning av fossila bränslen för att producera värme, som sedan utnyttjas för att generera el. Ett sätt att generera el från värme är att använda en Rankine-cykel. Grundprincipen för en Rankine-cykel är att värma upp en vätska till dess kokpunkt, vilket orsakar en tryckökning som används för att snurra en turbin, kopplad till en generator. Många industrier, som exempelvis transport och tillverkning, producerar stora mängder restvärme som måste avlägsnas från huvudprocessen. En variant av Rankine-cykeln som kallas organisk Rankinecykel kan användas i ett värmekraftsystem för att generera elektricitet från restvärme med lägre temperatur, vilket ökar effektiviteten eftersom mindre värme går förlorad. Detta examensarbete fokuserar på att konstruera en dynamisk modell av Climeons värmekraftsystem vid namn HP300. HP300 använder en organisk Rankine-cykel för att generera elektricitet. Dynamisk modellering är värdefull eftersom den ger en djupare förståelse av systemet, vilket är fördelaktigt för dess utveckling och förbättring. Dessutom har en systemmodell potentialen att förbättra systemets prestanda genom att använda avancerade reglermetoder. HP300 består av fyra huvudkomponenter: en pump, en turbin, en förångare och en kondensor. Varje komponent modelleras individuellt och hela modellen konstrueras genom att komponentmodellerna kombineras. Dessutom utförs en fördjupad undersökning av en avancerad modelleringsmetod av värmeväxlare. Den konstruerade modelled i detta arbete har ett genomsnittligt fel på 4%. Pumpen och turbinen modellerades som stationära modeller, medan förångaren och kondensorn modellerades med datadrivna state-space-modeller. Modellens viktigaste variabel är den effekt som genereras av turbinen. Den modellerade effekten hade ett genomsnittligt fel på 6%. Turbinmodellen presterar bäst för tryck-kvoter på 1, 75 och högre. Kondensor modellen hade större fel än förångaren eftersom den hade färre ingångsvariabler. En förbättring av kondensorns modell skulle förbättra modellens övergripande noggrannhet.

Rising energy demands and the continual push to find more energy efficient technologies have been the impetus for the investigation of waste heat recovery techniques. Diesel engine exhaust heat utilization has the potential to significantly reduce the consumption of fossil fuels and reduce the release of greenhouse gases, because diesel engines are ubiquitous in industry and transportation. The exhaust energy can used to provide refrigeration by implementing an organic Rankine cycle coupled with a vapor-compression cycle. A critical component in this system, and in any waste heat recovery system, is the heat exchanger that extracts the heat from the exhaust. In this study, a cross-flow microchannel heat exchanger was geometrically examined and thermally tested under laboratory conditions. The heat exchanger, referred to as the Heat Recovery Unit (HRU), was designed to transfer diesel exhaust energy to a heat transfer oil. Two methods were developed to measure the geometry of the microchannels. The first was based on image processing of microscope photographs, and the second involved an analysis of profilometer measurements. Both methods revealed that the exhaust channels (air channels) were, on average, smaller in cross-sectional area by 11% when compared to the design. The cross-sectional area of the oil channels were 8% smaller than their design. The hydraulic diameters for both channel geometries were close to their design. Hot air was used to simulate diesel engine exhaust. Thermal testing of the heat exchanger included measurements of heat transfer, effectiveness, air pressure drop, and oil pressure drop. The experimental results for the heat transfer and effectiveness agreed well with the model predictions. However, the measured air pressure drop and oil pressure drop were significantly higher than the model. The discrepancy was attributed to the model's ideal representation of the channel areas. Additionally, since the model did not account for the complex flow path of the oil stream, the measured oil pressure drop was much higher than the predicted pressure drop. The highest duty of the Heat Recovery Unit observed during the experimental tests was 12.3 kW and the highest effectiveness was 97.8%. To examine the flow distribution through the air channels, velocity measurements were collected at the outlet of the Heat Recovery Unit using a hot film anemometer. For unheated air flow, the profile measurements indicated that there was flow maldistribution. A temperature profile was measured and analyzed for a thermally loaded condition. / Graduation date: 2012

Solar energy is a virtually inexhaustible energy resource, and thus, has great potential in helping meet many of our future energy requirements. Current technology used for solar energy conversion, however, is not cost effective. In addition, solar thermal power systems are also generally less efficient as compared to fossil fuel based thermal power plants. There is a large variety of systems for solar thermal power generation, each with certain advantages and disadvantages. A distinct advantage of solar thermal power generation systems is that they can be easily integrated with a storage system and/or with an auxiliary heating system (as in hybrid power systems) to provide stable and reliable power. Also, as the power block of a solar thermal plant resembles that of a conventional thermal power plant, most of the equipment and technology used is already well defined, and hence does not require major break through research for effective utilisation. Manufacturing of components, too, can be easily indigenized. A solar collector field is generally used for solar thermal energy conversion. The field converts high grade radiation energy to low grade heat energy, which will inevitably involve energy losses as per the laws of thermodynamics. The 2nd law of thermodynamics requires that a certain amount of heat energy cannot be utilised and has to be rejected as waste heat. This limits the efficiency of solar thermal energy technology. However, in many situations, the waste heat can be effectively utilized to perform refrigeration and desalination using absorption or solid sorption systems, with technologies popularly known as “polygeneration”. There is extensive research done in the area of solar collectors, including but not limiting to thermal analysis, testing of solar collectors, and economic analysis of solar collectors. Exergy and optimization analyses have also been done for certain solar collector configurations. Research on solar thermal power plants includes energy analysis at system level with certain configurations. Research containing analysis with insolation varying throughout the day is limited. Hence, there is scope for analysis incorporating diurnal variation of insolation for a solar thermal power system. This thesis centres on the thermodynamic analysis at system level of a solar thermal power system using a concentrating solar collector field and a simple Rankine cycle power generation (with steam as the working fluid) for Indian conditions. The aim is to develop a tool for thermodynamic analysis of solar thermal power systems, with a generalised approach that can also be used with different solar collector types, different heat transfer fluids in the primary loop, and also different working fluids in the secondary loop. This analysis emphasises the solar collector field and a basic sensible heat storage system, and investigates the various energy and exergy losses present. Comparisons have been made with and without a storage unit and resulting performance issues of solar thermal power plants have been studied. Differences between the system under consideration and commercially used thermal power plants have also been discussed, which brought out certain limitations of the technology currently in use. A solution from an optimization analysis has been utilized and modified for maximization of exergy generated at collector field. The analysis has been done with models incorporating equations using the laws of thermodynamics. MATLAB has been used to program and simulate the models. Solar radiation data used is from NREL’s Indian Solar Resource Data, which is obtained using their SUNY model by interpreting satellite imagery. The performance of the system has been analysed for Bangalore for four different days with different daylight durations, each day having certain differences in the incident solar radiation or insolation received. A particular solution of an optimization analysis has been modified using the simulation model developed and analysed with the objective of maximization of exergy generated at collector field. It has been found that the performance of the solar thermal power system was largely dependent on the variation of incident solar radiation. The storage system provided a stableperformance for short duration interruptions of solar radiation occurred on Autumn Equinox (23-09-2002).The duration of the interruption was within the limits of storage unit capacity. The major disruption in insolation transpired on Summer Solstice (21-06-2002) caused a significantly large drop in the solar thermal system performance; practically the system ceased to function due to lack of energy resource. Hence, the use of an auxiliary heating system hasbeen considered desirable. The absence of a storage unit has been shown to cause a significant loss in gross performance of the power system. The Rankine cycle turbine had many issues coping with a highly fluctuating energy input, and thus caused efficiency losses and even ceased power generation. A storage unit has been found to be ideal for steady power generation purposes. Some commercial configurations may lack a storage system, but they have been compensated by the auxiliary heating system to ensure stable power generation. The optimization of the solar collector determines that optimal collector temperatures vary in accordance to the incident solar radiation. Hence, the collector fluid outlet temperature must not be fixed so as to handle varying insolation for optimal exergy extraction. The optimal temperatures determined for Bangalore are around 576 K which is close to the values obtained by the simulation of the solar thermal power system. The tools for analysis and simulation of solar thermal power plants developed in this thesis is fairly generalised, as it can be adapted for various types of solar collectors and for different working fluids (other than steam), such as for Organic Rankine Cycle (ORC). The model can also be easily extended to other types of power cycles such as Brayton and Stirling cycles.

Dirigé par la société Fonroche Géothermie, un consortium de dix partenaires participe au projet FONGEOSEC qui s’inscrit dans le cadre des Investissements d’Avenir de l’ADEME. Ce projet a pour but de concevoir et de réaliser un démonstrateur innovant de centrale géothermique haute enthalpie. L’énergie, ainsi récupérée en profondeur, servira à la cogénération d’électricité et de chaleur. L’une des étapes du projet correspond à l’objectif de cette thèse : développer une méthodologie pour la conception optimale des activités de surface de la centrale géothermique. Il s’agit donc de formuler le problème d’optimisation, de proposer une stratégie de résolution robuste et enfin, de mettre en oeuvre cette stratégie grâce à un outil logiciel.Dans l’outil ainsi développé, la répartition entre la production d’électricité et de chaleur s’effectue en parallèle. Le fluide géothermal est séparé en deux courants, l’un alimentant un Cycle Organique de Rankine (ORC : Organic Rankine Cycle) pour la production d’électricité, et l’autre étant relié à un Réseau de Chaleur Urbain (RCU) pour la distribution de la chaleur. Chaque constituant de l’ORC est dimensionné et la topologie du RCU est déterminée. Cet outil permet alors de déterminer simultanément :quelle est la meilleure répartition entre production d’électricité et de chaleur,quelles sont les meilleures dimensions pour les composants de l’ORC,et quelle est la meilleure topologie du RCU.Concernant l’ORC, l’outil permettra de savoir si l’utilisation d’un éventuel récupérateur de chaleur interne (IHE : Internal Heat Exchanger) est avantageuse ou non. Du point de vue du RCU, tous les consommateurs (sous-stations) envisagés ne sont pas obligatoires. L’outil permettra de choisir quels consommateurs relier au réseau et dans quelle disposition. L’utilisation de variables discrètes est alors nécessaire et le problème d’optimisation ainsi résolu est un problème de type MINLP (Mixed Integer Non Linear Programming).Une méthodologie de résolution permettant l’obtention d’une solution de « confiance » (probablement, mais non certainement, l’optimum global) est proposée. Cette stratégie de résolution est testée pour différents cas d’étude proches des conditions du projet FONGEOSEC. La stabilité et la robustesse de cette stratégie sont alors mises en avant. Une analyse économique et une analyse énergétique sont réalisées. La résolution multi-objectif est alors effectuée dans le but de fournir le meilleur compromis entre bénéfices annuels nets et destruction d’exergie. Pour finir, la diversité des résultats montre qu’il n’est pas satisfaisant de dissocier les études des deux systèmes (ORC et RCU) et démontre l’intérêt de l’outil développé. / A consortium of ten partners, led by “FONROCHE Géothermie”, works on the FONGEOSEC project, an “Investissement d’Avenir” organized by the French Agency for Environment and Energy (ADEME). The aim of this project is to design and create an innovative demonstrator of a high-energy geothermal power plant. The geothermal energy will be used to produce electricity and heat. Among other tasks, this project aims to develop a support tool for the optimal design of the structure for the surface activities in the geothermal plant.Within the developed tool, the repartition between electricity and heat production is in parallel. The geothermal fluid is split in two streams, one is used for an Organic Rankine Cycle (ORC) for electricity production, and the other is connected to a District Heating Network (DHN) for the heat distribution. This tool enables to determine simultaneously:which is the best repartition between electricity and heat,which is the best sizing for ORC components,which is the best configuration for the DHN.About the ORC, the tool will enable to decide if the use of an Internal Heat Exchanger (IHE) is interesting or not. For the DHN point of view, all the consumers envisaged are not mandatory. The tool will enable to choose which consumers it is better to connect to the network and in which disposition. The use of discrete variables is necessary and the optimization problem to be solved is a MINLP (Mixed Integer Non Linear Programming) problem.A solution strategy is implemented in order to obtain a confident solution with a determinist algorithm. This strategy is tested for different study cases close to FONGEOSEC conditions. Stability and Robustness of this strategy are then highlighted. An economic and an exergetic analysis are carried out. In order to find a good compromise between the two objectives, a multi-objective solution is performed. Finally, the diversity of results obtained shows it is not suitable to dissociate ORC and DHN studies and shows the interest of the developed tool.

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.

Les fumées à basse température (<120-150 °C) sortant des procédés industriels pourraient être récupérées pour la production d'électricité et constituent un moyen efficace de réduction de la consommation d'énergie primaire et des émissions de dioxyde de carbone. Cependant, des barrières techniques tels que la faible efficacité de conversion, la nécessité d'une grande zone de transfert de chaleur, et la présence de substances chimiques corrosives liées à une forte teneur en humidité lors du fonctionnement en environnement sévère entravent leur application plus large. Cette thèse porte particulièrement sur les secteurs industriels les plus énergivores rencontrant actuellement des difficultés à récupérer l'énergie des sources de chaleur à basse température dans des environnements hostiles. Des cycles thermodynamiques existants basés sur le Cycle de Rankine Organique (ORC) sont adaptés et optimisés pour ce niveau de température. Deux méthodes de récupération de chaleur classiques sont étudiées plus particulièrement : les déshumidifications à contact direct et indirect. Des méthodes de conception optimisées pour les échangeurs de chaleur sont élaborées et validées expérimentalement. Pour la déshumidification à contact indirect, des matériaux à revêtement anticorrosifs sont proposés et testés. Pour la déshumidification à contact direct, les effets du type et de la géométrie des garnissages sur les performances hydrauliques sont étudiés. Des cycles thermodynamiques innovants basés sur la technologie de déshydratation liquide sont proposés. Un cycle de régénération amélioré (IRC) est développé. Comparé aux technologies de récupération de chaleur classiques, l'IRC proposé améliore à la fois la puissance nette et le taux de détente de la turbine en prévenant par ailleurs les problèmes de corrosion. / Low-temperature waste-gas heat sources (< 120-150°C) exiting several industrial processes could be recovered for electricity production and constitute an effective mean to reduce primary energy consumption and carbon dioxide emissions. However, technical barriers such as low conversion efficiency, large needed heat transfer area, and the presence of chemically corrosive substances associated with high moisture content when operating in harsh environment impede their wider application. This thesis focuses on particularly energy-hungry industrial sectors characterized by presently unsolved challenges in terms of environmentally hostile low-temperature heat sources. Existing thermodynamic cycles based on Organic Rankine Cycle (ORC) are adapted and optimized for this temperature level. Two conventional heat recovery methods are studied more particularly: indirect and direct contact dehumidification. Optimized design methods for heat exchangers are elaborated and experimentally validated. For the indirect contact dehumidification, advanced anti-corrosion coated materials are proposed and laboratory tested. For the direct contact dehumidification, the effects of packing material and geometry on the corresponding hydraulic performances are underlined. Innovative thermodynamic cycles based on the liquid desiccant technology are investigated. An improved regeneration cycle (IRC) is developed. Compared to the conventional heat recovery technologies, the proposed “IRC” improves both net power and turbine expansion ratio besides preventing faced corrosions problems.

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.

La production d'électricité dépend étroitement de la disponibilité d'une source froide. C'est la raison pour laquelle la plupart des centrales de grande puissance dans le monde sont construites près d'une source d'eau. Le problème de la source froide a été soulevé à plusieurs reprises en France, notamment après les canicules de 2003 et de 2006. Le refroidissement à l'air sec est une des options possibles. Cependant, étant donné le besoin de surface d'échange plus important, le changement de la source froide pour l'air ambiant n'est pas, dans la majorité des cas, viable économiquement.Une des solutions à ce problème imaginées à EDF était de changer l'architecture du cycle de production en considérant un cycle de production composé de deux cycles de Rankine en cascade, le premier fonctionnant avec de la vapeur d'eau et le deuxième fonctionnant avec de l'ammoniac dont la vapeur à basse pression est beaucoup plus dense que celle de l'eau. Cette solution permet de faciliter l'utilisation d'un aérocondenseur et de réduire la taille de la salle machine.En raison de la nature toxique et corrosive de l'ammoniac, il est intéressant d'étudier la possibilité de remplacer ce dernier par d'autres fluides plus adaptés, notamment en envisageant de nouveaux fluides pour lesquels peu ou pas de données sont disponibles. Nous comparons les fluides sur le plan énergétique et en terme de taille des composants de l'installation.Cette thèse illustre la démarche des différentes étapes de notre travail : la recherche de nouveaux fluides de travail, l'évaluation de performance du système en régime nominal et non-nominal, le dimensionnement des principaux composants du cycle ainsi que l'évaluation de coût et de gain économique éventuel. / This work considers a two stage Rankine cycle architecture slightly different from a standard Rankine cycle for electricity generation. Instead of expanding the steam to extremely low pressure, the vapor leaves the turbine at a higher pressure then having a much smaller specific volume. It is thus possible to greatly reduce the size of the steam turbine. The remaining energy is recovered by a bottoming cycle using a working fluid which has a much higher density than the water steam. Thus, the turbines and heat exchangers are more compact; the turbine exhaust velocity loss is lower. This configuration enables to largely reduce the global size of the steam water turbine and facilitate the use of a dry cooling system.The main advantage of such an air cooled two stage Rankine cycle is the possibility to choose the installation site of a large or medium power plant without the need of a large and constantly available water source; in addition, as compared to water cooled cycles, the risk regarding future operations is reduced (climate conditions may affect water availability or temperature, and imply changes in the water supply regulatory rules).The concept has been investigated by EDF R&D. A 22 MW prototype was developed in 70s using ammonia as the working fluid of the bottoming cycle for its high density and high latent heat. However, this fluid is toxic. In order to search more suitable working fluids for the two stage Rankine cycle application and to identify the optimal cycle configuration, we have established a working fluid selection methodology. Some potential candidates have been identified. We have evaluated the performances of the two stage Rankine cycles operating with different working fluids in both design and off design conditions. For the most acceptable working fluids, components of the cycle have been sized. The power plant concept can then be evaluated on a life cycle cost basis.