The air conditioning systems currently utilized in automobiles are the vapor compression systems. This type of system has many disadvantages: the refrigerant used is not environmentally friendly, the compressor is in competition with the engine coolant system, and the compressor uses a significant portion of the engine power. A waste heat driven absorption refrigeration system is one alternative to the current systems that could address these problems. The absorption refrigeration system uses solutions for the absorbent-refrigerant pair that do not harm the environment. This investigation includes a theoretical analysis of the feasibility of absorption air conditioning system in automotive applications. Also, a comparison of the power requirements of the proposed system and the vapor compression system is performed.

Orientador: Silvia Azucena Nebra de Perez / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-11T16:10:36Z (GMT). No. of bitstreams: 1 PalaciosBereche_Reynaldo_M.pdf: 8960679 bytes, checksum: a6e8e552788d00fa0fb258923ebe13a9 (MD5) Previous issue date: 2008 / Resumo: Neste trabalho e feita uma revisão em relação à participação do gás natural na matriz energética mundial, brasileira e no Estado de São Paulo. Características do setor terciário, assim como da utilização do gás natural neste setor de consumo, são apresentadas também na primeira parte. Foi feita uma revisão das tecnologias de utilização de gás natural no setor terciário, assim como da tecnologia dos sistemas de refrigeração por absorção, das diferentes configurações do ciclo, e dos fluidos de trabalho utilizados neste tipo de sistema. Uma metodologia para o calculo da exergia da solução água brometo de lítio, comumente utilizada como fluido de trabalho em sistemas de refrigeração por absorção para condicionamento de ambientes, foi elaborada. Para a realização das analises exegética e exergoeconomica do sistema foi realizado o calculo da exergia total dos fluidos de trabalho considerando as parcelas de exergia química e física. A analise exegética compreendeu o calculo da irreversibilidade em cada componente do sistema assim como da total. Na ultima parte do trabalho foi realizada a analise termodinâmica, exegética e exergoeconomica do sistema de refrigeração por absorção de simples e duplo efeito H2O/LiBr, considerando como fontes de aquecimento um sistema de queima direta de gás natural e energia de rejeito de um sistema de cogeração. Os resultados são comparados e discutidos / Abstract: A review about the participation of the natural gas in the energetic matrix was done in this work, considering the scope international, Brazilian and the Sao Paulo State. Characteristics of the tertiary sector and the natural gas utilization in this consumption sector are also presented. A review about the technologies of utilization of natural gas in the tertiary sector was also done. In the following part, the technology of absorption refrigeration systems, different configurations of the cycle and working fluids were reviewed. A methodology for the exergy calculation of the lithium bromide ¿ water solution was elaborated. The lithium bromide ¿ water solution is widely utilized as working fluid in absorption refrigeration system for air conditioning. The exergy calculation takes in account the chemical and physical parcel of the exergy, which is important to realize the exergetic and exergoeconomic analysis of the system. In the last part of the work it was done a thermodynamic, exergetic and exergoeconomic analysis of the absorption refrigeration system H2O/LiBr of single and double effect. The exergetic analysis included the irreversibility calculation in each component and the total irreversibility of the system. Two different energy sources were considered: direct heating through natural gas combustion and the utilization of rejected energy in a cogeneration system. The different results were compared. / Mestrado / Mestre em Planejamento de Sistemas Energéticos

Le stockage de l'énergie solaire thermique s'avère aujourd'hui nécessaire si on veut atteindre une meilleure efficacité et une utilisation à grande échelle de cette ressource. Le stockage sous forme de potentiel chimique se révèle être adapté au stockage de chaleur sur le long terme (cycles saisonniers ou pluriannuels) parce qu'il présente les moindres pertes thermiques par rapport au stockage sensible ou latent. Malgré les avancées significatives faites ces dernières années dans ce domaine, il n'existe pas aujourd'hui de système achevé dédié à ce type de stockage. Le but du présent travail est de démontrer la faisabilité d'un procédé de stockage de chaleur solaire à long terme par absorption pour le chauffage des bâtiments. La chaleur est stockée en été grâce à la désorption et restituée en hiver à travers l'absorption. Une analyse multicritère portant des couples de sorption possibles a permis d'identifier le couple LiBr−H2O pour la démonstration de faisabilité du concept. Il a été montré que la cristallisation d'une partie de la solution permet de multiplier par trois la densité de stockage énergétique et donc d'améliorer la compétitivité du procédé. Un modèle dynamique a été développé pour dimensionner et simuler les performances du système sous différentes conditions opératoires. De nombreuses simulations paramétriques ont permis de discuter de l'influence de différents paramètres et aspects du contrôle du procédé. Cela a donné lieu à la conception et au dimensionnement d'un prototype de démonstration capable de stocker 8 kWh de chaleur et de produire une puissance moyenne de chauffage de 1 kW. Ce prototype a été construit et expérimenté en fonctionnement statique et dynamique sur un banc d'essai, dans des conditions compatibles avec une installation solaire domestique. La faisabilité de la charge du procédé a ainsi été démontrée. L'absorption durant la phase de décharge est effective bien que des problèmes, dus notamment à une conception inadaptée de l'absorbeur, n'ont pas permis d'assurer la restitution de la chaleur. Différents aspects tels que la stratification et la circulation de la solution dans son réservoir ont également été abordés. La confrontation du modèle et des résultats expérimentaux a ainsi été réalisée et discutée. / Energy storage is a key component to improve the efficiency of energy systems, especially when the energy source is intermittent, such as solar energy. Heat storage systems based on sorption processes are relevant in case of long-term storage (seasonal or pluriannual storage) because of their acceptable heat losses. Even though considerable breakthroughs have been made in the past decades, there is no mature long-term sorption heat storage yet. The aim of this work is to demonstrate the feasibility of a long term solar thermal storage by absorption for building space heating. Solar heat is stored in summer using desorption process and released in winter via absorption. A multicriteria analysis on various possible absorption couples leads to the choice of LiBr−H2O as storage media for the concept feasibility demonstration. It has been shown that crystallisation in the solution storage tank can increase the storage density by three times and therefore, is relevant for the process competiveness. A dynamic model has been developed for the system design and simulations under various operating conditions were performed. A lot of parametric simulations are used to investigate the influence of certain parameters and controls aspects. This helps designing a demonstrative prototype that can store 8 kWh of heat and can produce a heating power of 1 kW. The prototype has been built and tested on a test bed in static and dynamic operating conditions that are compatible with domestic solar thermal plants. The charging process has been proved successful. Absorption during discharging phase is also verified. However, some problems related to the absorber design have not made possible to observe the heat release as expected. Various aspects such as stratification and circulation in the solution storage tank have also been addressed. The model comparison with experimental result is then performed and discussed.