Increasingly intensive efforts are being made to enhance energy systems via augmented introduction of renewable energy along with improved energy efficiency. Resource constraints and sustained high fossil fuel prices have created a new phenomenon in the world market. Enhanced energy security and renewable energy development are currently high on public agenda worldwide for achieving a high standard of welfare for future generations. Biomass and municipal solid waste (MSW) have widely been accepted as important locally-available renewable energy sources offering low carbon dioxide (CO2) emissions. Concerning solid waste management, it has become a critical issue in Southeast Asia since the most popular form for waste disposal still employs open dumping and landfilling. While the need for a complete sustainable energy solution is apparent, solid waste management is also an essential objective, so it makes sense to explore ways in which the two can be joined. Electricity production in combination with energy recovery from flue gases in thermal treatment plants is an integral part of MSW management for many industrialized nations. In Sweden, MSW is considered as an important fuel resource for partially meeting EU environmental targets within cogeneration. However it is normally difficult to justify traditional cogeneration in tropical locations since there is little need for the heat produced. Similarly, MSW-fired cogeneration usually operates with low capacity during non-heating season in Sweden. Therefore, it is very important to find new alternatives for energy applications from waste, such as the implementation of thermally driven cooling processes via absorption cooling in addition to electricity production. The work presented herein concentrates first on an investigation of electricity generation from MSW power plants and various energy applications from waste in tropical urban areas. The potential for various types of absorption chillers driven by MSW power plants for providing both electricity and cooling is of particular interest. Additionally a demonstration and analysis of decentralized thermally driven cooling in district heating network supplied by low temperature heat from a cogeneration of MSW have been conducted. This study aims at developing the best system configuration as well as finding improved system design and control for a combination of district heating and distributed thermally driven cooling. Results show that MSW incineration has the ability to lessen environmental impacts associated with waste disposal, and it can contribute positively towards expanding biomass-based energy production in Southeast Asia. For electricity production, the proposed hybrid dual-fuel (MSW/natural gas) cycles feature attractive electrical efficiency improvements, leading to greenhouse gas emissions reduction. Cogeneration coupled with thermally driven cooling is a solution that holds promise for uniting enhanced sustainability with economic advantages. The system offers great opportunity for primary energy saving, increasing electrical yield and can significantly reduce CO2 emissions per unit of cooling as compared to compression chiller. The demonstration and simulation have also revealed that there is a potential with some modifications and improvements to employ decentralized thermally driven cooling in district heating networks even in temperate regions like Sweden. Thus, expanding cogeneration towards trigeneration can augment the energy supply for summer months in Europe and for year-round cooling in tropical locations. / QC 20110408

Le problème du réchauffement climatique actuel conduit au renforcement des règlementations environnementales. Ainsi, le domaine du génie climatique est affecté par ces évolutions réglementaires, ce qui impose le passage à une nouvelle génération de réfrigérants à plus bas impact environnemental. Dans cette thèse, ce sujet est étudié dans le cas des groupes refroidisseurs d’eau utilisant le R-410A qui est visé par la réglementation. Mais, résoudre ce problème ne s’arrête pas au simple changement du réfrigérant par un autre à plus bas GWP ; il faut que la transition soit accompagnée par une amélioration ou un maintien de la puissance frigorifique et de la performance énergétique du système par crainte d’avoir un effet environnemental inverse parce que la consommation énergétique représente un plus grand effet sur l’impact environnemental que celui du GWP du réfrigérant.Une revue de la littérature et des tests expérimentaux réalisés en remplaçant le R-410A montrent que les réfrigérants présents sur le marché et proposés par les fabricants pour remplacer le R-410A ne permettent pas d’avoir les améliorations souhaitées. Parmi ces substituants le R-32 est le plus utilisé et semble être prometteur mais avec une réduction du COP et des températures de refoulement du compresseur très élevées. Ainsi, la solution de la compression refroidie par injection d’huile de lubrification au niveau du compresseur est étudiée et modélisée. Le modèle théorique montre qu’elle permet de refroidir la compression et de réduire la consommation du compresseur à condition d’avoir des gouttes d’huile très fines avec un débit et une température de l’huile injectée contrôlables.Pour appliquer cette solution, un système d’atomisation de l’huile est conçu et testé ; les résultats montrent qu’il estpossible de créer un spray de gouttes très fines pour des pressions d’injection de l’ordre de la différence entre la haute et labasse pression du groupe refroidisseur d’eau. La compression refroidie est testée en connectant le système d’atomisationde l’huile au groupe refroidisseur d’eau. Une réduction de la température de refoulement du compresseur et de lapuissance consommée par le compresseur est mesurée, mais elle est plus faible que la réduction prévue théoriquement. Enintégrant une augmentation du diamètre des gouttes durant la compression dans le modèle théorique, les résultats de la simulation sont proches des résultats expérimentaux. / Current global warming problem leads to more stringent environmental standards. Thus the HVAC field is affected by these standard changes, which requires the transition to a new generation of refrigerants with lower environmental impact. In this thesis, this aspect is studied in the case of water chillers using R-410A that is subject to substitution due to new standards. But solving this problem doesn’t stop at mere refrigerant change by another with lower GWP. It is necessary that improvement or maintain of cooling capacity and energy efficiency of the system accompanies this transition by fear of having a reverse effect because global energy consumption represents a greater effect on the environmental impact than refrigerant GWP.A review of literature and experimental tests carried out by replacing R-410A show that refrigerants used in the market and offered by manufacturers to replace R-410A don’t allow the desired improvements. Among these substituents, R-32 is the most used and seems promising, but it causes a decrease of COP and very high compressor discharge temperatures. Thus, the solution of cooled compression by injection of lubricating oil in the compressor is studied and modeled. The theoretical model shows that this solution helps cooling the compression and reduces compressor power consumption provided that injection is characterized by very fine drops of oil with controllable flowrate and oil temperature.To implement this solution, an oil atomization system is designed and tested, the results show that it is possible to create a spray of very fine droplets for injection pressures of the order of the difference between the high and low pressures of the water chiller. Cooled compression is then tested by connecting the oil atomization system to the water chiller. Reductions of compressor discharge temperature and of compressor power consumption are measured, but measured reductions are lower than the theoretical expected reductions. By integrating an increased droplet

La maîtrise de la demande en climatisation des bâtiments tertiaires peut contribuer à la limitation du réchauffement climatique à 2°C. Les réseaux de froid urbain sont une solution pour répondre à cette demande avec une haute efficacité énergétique. Une conduite performante est cependant essentielle pour maintenir et augmenter leurs avantages compétitifs. L'objectif de la thèse est de contribuer à la construction d'un outil d'aide à la conduite journalière des réseaux de froid. La difficulté réside à deux niveaux : la diversité des décisions et la complexité des phénomènes physiques sous-jacents. L'originalité est de proposer une méthodologie pour aider au pilotage des groupes frigorifiques, des tours aéroréfrigérantes, de la pression différentielle et de la répartition de puissance entre des centrales de production aux performances variables. La méthodologie développée est appliquée au réseau de froid de Paris-Bercy exploité par Climespace. Tout d'abord, un modèle intégrant une représentation physique des centrales de production, du réseau de distribution et des sous-stations, est développé. En particulier, un modèle de type semi-empirique, paramétrable sur des mesures, est modifié pour calculer les performances non-nominales des groupes frigorifiques centrifuges. La validation du modèle complet est réalisée sur un jeu de données indépendant de l'identification. Ensuite, le modèle est exploité pour rechercher une conduite optimisée à partir d'un modèle de prévision de la demande. La méthode proposée est séquentielle : résolution a priori des optimisations locales puis génération de modèles quadratiques de centrales servant à déterminer la répartition optimale. La pression différentielle est minimisée à partir de l'identification, par simulation, de la sous-station défavorisée. Enfin, la réduction de la consommation électrique est évaluée sur une semaine d'été. / Cooling demand management of commercial buildings can contribute to limit global warming below 2°C. District cooling is an energy-efficient option. However, improving operational performance is of great importance to ensure and increase its competitive advantages. The aim of this thesis is to contribute to the development of a decision-support tool for daily operation of district cooling networks. Challenges lie at two levels: diversity of decisions to be taken and complexity of physical phenomena involved. The original aspect of our work is to propose a methodology to improve chillers and cooling towers control, differential pressure management and dispatching between production plants with variable efficiency. Our developments are applied to the district cooling of Paris-Bercy, operated by Climespace. First; a model featuring a physical description of chilled-water production plants, distribution network and buildings substations, is developed. In particular, a semi-empirical model with identified parameters is modified to compute non-nominal characteristics of centrifugal chillers. The system model is validated against an independent dataset. Then, the model is used to find optimized controls from cooling loads forecast. The proposed methodology is sequential: pre-computation of optimal set-points at plant level and then generation of quadratic plant models to solve the dispatching optimization problem at each time step. Differential pressure is minimized with a simulation-based tracking of the critical substation. To conclude, electricity consumption reduction with optimized controls is evaluated during a summer week.

e master's thesis clarifies the concept of trigeneration and the principle of absorbing cooling. Compare the advantages and disadvantages of this method of manufacture cool with compressor cooling. It presents an overview of the implementation of a developing cold absorption and performance. Acquainted with the types of absorption chillers of the two leading suppliers, their characteristics and existing applications of these refrigeration units in operation in the Czech Republic and abroad. It also assesses the possibility of using these units in conjunction with a cogeneration unit powered by internal combustion engine. It follows from the economic assessment of costs and income of the absorption chillers and compressor chillers and on concrete examples and an assessment of the effectiveness of the various options.