Increased demand for energy, rising energy costs, and heightened environmental concerns are driving forces that continually press for the improvement and development of new technologies to promote energy savings and emissions reduction. Combined heating and power (CHP), combined cooling, heating, and power (CCHP), and organic Rankine cycles (ORC) are a few of the technologies that promise to reduce primary energy consumption (PEC), cost, and emissions. CHP systems generate electricity at or near the place of consumption using a prime mover, e.g. a combustion engine or a turbine, and utilize the accompanying exhaust heat that would otherwise be wasted to satisfy the building’s thermal demand. In the case of CCHP systems, exhaust heat also goes to satisfy a cooling load. An organic Rankine cycle (ORC) combined with a CHP or CCHP system can generate electricity from any surplus low-grade heat, thereby reducing the total primary energy, cost, and emissions. This research first presents a review of the economical, energetic, and environmental benefits of CHP and CHP-ORC systems for a small office in various climates. Operating the systems 24 hours a day is compared to operating the system during typical office hours and benefits of the CHP system in terms of the EnergyStar and LEED programs are presented. Another objective of this dissertation is to study the critical role of the prime mover on the performance of CHP, CCHP, CHP-ORC, and CCHP-ORC systems under different pricing structures. Three different size natural gas engines are simulated for a small office under different operational strategies such as: follow the facility's electric demand, follow the facility's thermal demand, and follow a constant load. Simple optimizations were carried out to improve the system's performance. Using real prices for electricity and fuel to compute operational costs was compared to using the building's average prices without a CCHP system. Finally, a CCHP system using a load-share turbine for a large office building was examined while considering the source of carbon dioxide emissions, carbon offsetting through purchasing carbon credits, and available capital costs.

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<p>As a part of the fight against the global warming the energy production needs to be more efficient and redirected towards sustainable options. One alternative is cogeneration, which means that electricity and heat is produced in one plant. The purpose with this survey is to examine if there are any commercial available combined heat and power techniques, based on combustion of solid moist biomass, which are suitable to small-scale applications. The technique must be able to produce between 2 and 10 MW thermal and the heat demand is a Swedish district-heating system. When already published reports had been studied, the Organic Rankine Cycle (ORC) was chosen as the most suitable technique. The possibility of using the ORC to generate electricity from the district-heating return flow was considered simultaneously. The chosen ORC-technique was then evaluated in Excel. The first aspect to be examined was how the performance of a combined heat and power plant was affected by variations in the supply line temperature. It showed that the performance reaches top levels when the temperature is low. The second part contains an optimisation, in a techno-economical perspective, of the ratio between cogeneration and separate heat production for district-heating systems with heat demands below 50 GWh/year. The most profitable combined heat and power plant generates 45 % of the installed power in a 50 GWh system. The profit is, however, too low to justify any construction plans. The conclusion was that there are no economical reasons to choose combined heat and power based on an organic rankine cycle in Sweden today.</p>

As a part of the fight against the global warming the energy production needs to be more efficient and redirected towards sustainable options. One alternative is cogeneration, which means that electricity and heat is produced in one plant. The purpose with this survey is to examine if there are any commercial available combined heat and power techniques, based on combustion of solid moist biomass, which are suitable to small-scale applications. The technique must be able to produce between 2 and 10 MW thermal and the heat demand is a Swedish district-heating system. When already published reports had been studied, the Organic Rankine Cycle (ORC) was chosen as the most suitable technique. The possibility of using the ORC to generate electricity from the district-heating return flow was considered simultaneously. The chosen ORC-technique was then evaluated in Excel. The first aspect to be examined was how the performance of a combined heat and power plant was affected by variations in the supply line temperature. It showed that the performance reaches top levels when the temperature is low. The second part contains an optimisation, in a techno-economical perspective, of the ratio between cogeneration and separate heat production for district-heating systems with heat demands below 50 GWh/year. The most profitable combined heat and power plant generates 45 % of the installed power in a 50 GWh system. The profit is, however, too low to justify any construction plans. The conclusion was that there are no economical reasons to choose combined heat and power based on an organic rankine cycle in Sweden today.

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.

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.

Chez les animaux, la conformation unique du noyau du spermatozoïde dont la chromatine est organisée avec des protéines chromosomiques spécifiques telles que les protamines le rend totalement inactif. Le remodelage de la chromatine paternelle à la fécondation par des activités d'origine maternelle sont donc des processus essentiels à la formation d'un embryon diploïde, dont les mécanismes restent très mal connus. Lors de ma thèse j'ai essayé de mieux comprendre ces processus par l'étude, chez la drosophile, d'un mutant létal embryonnaire à effet maternel : maternal haploid (mh). Ce mutant affecte l'incorporation des chromosomes paternels à la première division zygotique menant à la formation d'embryons haploïdes gynogénétiques. L'identification du gène de mh comme CG9203 m'ont permis de caractériser sa fonction. Dans les œufs mh, les chromosomes paternels se condensent anormalement et ne parviennent pas à se diviser correctement lors de la première mitose de l'embryon. Récemment, des études sur son orthologue humain, appelé Spartan/DVC1, ont montré qu'il était impliqué dans la synthèse translésionnelle (TLS), un mécanisme de tolérance aux dommages d'ADN. J'ai pu démontrer que dans les cellules somatiques, la fonction de Spartan dans le TLS est conservée chez la drosophile. Cependant, la fonction maternelle de MH ne relève pas du TLS canonique, mais permet de maintenir l'intégrité de l'ADN paternel avant la réplication. Ensemble, mes travaux soulignent la singularité du pronoyau mâle et la complexité que présente le maintien de son intégrité à la fécondation / In animals, sexual reproduction requires the union between two distinct parental gametes: the spermatozoon and the oocyte. The unique nuclear conformation of the sperm, in which the chromatin is organized with sperm-specific chromosomal protein like protamines, abolishes its activity. The paternal chromatin remodeling and the maintenance of its integrity at fertilization by maternal activities are therefore essential processes for zygote formation. However, although their mechanisms are crucial, they remain poorly understood. During my thesis, I tried to better understand the processes involved during de novo paternal chromatin assembly in Drosophila through the study of a maternal embryonic lethal mutation: maternal haploid (mh). The mutant affects the incorporation of paternal chromosomes during the first zygotic division, leading to the development of gynogenetic haploid embryos. The identification of the mh gene as CG9203, and the generation of the null allele mh2 allowed me to characterize its function. In eggs led by mh mutant females, paternal chromosomes abnormally condense and fail to divide leading to the formation of chromatin bridges at the first embryonic division. Recently, its human ortholog Spartan/DVC1, has been described to be involved in translesion synthesis (TLS), a DNA damage tolerance pathway that ensures replication fork progression. Combining genetic and cytological approaches, I demonstrated that the Spartan function in TLS is conserved in Drosophila. However, I discovered that the critical function of MH during the first embryonic division, was not consistent with a canonical TLS. Alternatively, it is specifically required to maintain paternal integrity and to allow its proper replication at the first cycle. The mh phenotype characterization, led me to compare it with others phenotypes induced by the knock-down of replication factors and to study parental chromosome condensation in the zygote. Surprisingly, one of the proteins allowing the establishment of the pre-replication complex is dispensable for the proper paternal chromosome segregation contrarily to the maternal counterpart. Altogether, these works highlight the difference that exists between the two parental pronuclei and the complexity of maintaining their integrity at fertilization

Energikontor Sydost har startat demonstrationsprojekt inom småskalig kraftvärme. Ronneby Miljö och Teknik AB driver en demonstrationsanläggning för småskalig elproduktion med ORC-turbin på värmeverk i Bräkne-Hoby. I samband med installation av ORC-turbin gjordes även ombyggnation av fjärrvärmeledning till närliggande sågverk. Detta examensarbete är en teknisk- och lönsamhetsanalys för utvärdering av investeringen. Elverkningsgrad uppgick för denna fjärrvärmesäsong till 2,23 %, alfa-värde till 2,3 %, systemverkningsgrad för ORC-system till 99,54 %. Ledningsförluster minskade från 19,7 till 17,25 % efter ombyggnation. Det visades även att sänkning av fjärrvärmereturtemperatur ökar elproduktionen. Investeringskalkyl visade en icke lönsam investering om el säljs externt. Att producera och använda el internt inom anläggningen visade sig lönsamt även utan investeringsstöd. Ombyggnation av fjärrvärmeledning visades även vara lönsamt. Tekniken är vid anslutning till värmeverk förnybar, lokal och har hög tillgänglighet vid högbelastningstider.