Orientadora: Profa. Dra. Silvia Azucena Nebra de Pérez / Tese ( doutorado)- Universidade Federal do ABC. Programa de Pós-Graduação em Energia, 2016. / O objetivo geral deste trabalho é obter uma abordagem termoeconômica sistemática que possa ser aplicada a qualquer sistema de potência e de refrigeração cujos fluidos de trabalho operem num ciclo termodinâmico. Para isso, é proposta uma interpretação termodinâmica dos termos gerados pela formulação dos Modelos H&S e UFS. Neste trabalho também é proposto um novo nível de desagregação da exergia física, chamado aqui Modelo UFS+, tal que supera a limitação do Modelo UFS quanto ao isolamento de dispositivos isentálpicos de estrangulamento quando o fluido expandido comporta-se como gás ideal. Uma comparação com as componentes térmica e mecânica é feita em tal situação. Além disso, um estudo de caso é feito, cujo sistema estudado é uma turbina a gás com reator nuclear operando em cogeração. Os resultados mostram que a desagregação total do sistema, em relação à construção do diagrama funcional, é obtida somente com a aplicação do Modelo UFS+. Também neste trabalho, propõe-se o desenvolvimento de uma sistemática livre de arbitrariedades para obtenção do insumo e do produto de um volume de controle qualquer. A sistemática proposta é aplicada para modelar vários componentes de engenharia. Além disso, um estudo de caso é feito, cujo sistema estudado é uma planta de refrigeração por compressão com dois evaporadores. Os resultados mostram que a sistemática pode ser aplicada para construção do diagrama funcional do sistema para todos os níveis de desagregação de exergia. Por fim, uma síntese dos resultados é feita, além da apresentação das contribuições deste trabalho e de sugestões para trabalhos futuros. / The main goal of this work is to develop a systematic thermoeconomic approach that can be applied to model any power and refrigeration thermodynamic cycles. In order to achieve such goal, it is proposed a thermodynamic meaning of the terms formulated by the H&S and UFS Models. In this work, it is also proposed a new physical exergy splitting level, here called UFS+ Model, which overcomes the UFS Model limitation regarding the throttling devices isolation when the working fluid behaves as an ideal gas. A comparison between the proposed model and the thermal and mechanical components is done. Also, it is done a case study, whose studied system is a nuclear gas turbine plant running in cogeneration mode. Results show that the total system disaggregation is obtained when one applies the UFS+ Model only, regarding the functional diagram drawing. In this work, it is also proposed the development of an arbitrariness free systematic to obtain fuel and product for any control volume. The proposal is applied to model some engineering equipment. Also, a case study is done, whose studied system is a compression refrigeration plant with two evaporators. Results show that the proposal can be applied to draw the system functional diagram for all exergy splitting levels. Finally, it is done a synthetic appraisal of results as well as the presentation of the contributions made by this work and suggestions for future research.

Solid propellant gas generators that have high gas capacity are used for fast pressurization of inflatable devices or elastic shells. However, many applications such as control surface actuation, air bottle pressurization in rocket engines and safety systems of automobiles (airbags) require exit gases at near ambient temperature. A scheme suitable for short duration applications is passive cooling of gas generator gases by using a packed bed as compact heat exchanger. A study indicated that the mass flow rates of solid propellant gas generators for applications such as air bottle pressurization and control system actuators were of the order of 1 kg/s. Since pressure and enthalpy drop correlations for packed beds with mass flow rates (~1 kg/s) and packing sphere based Reynolds number (Red) ~ 9X104 were unavailable in open literature, an experimental investigation was deemed necessary. The objectives of the present study were (a) characterization of packed beds for pressure and enthalpy drop, (b) develop Euler and Nusselt number correlations at Red~105 and (c) evolve an engineering procedure for estimation of packed bed pressure and enthalpy drop. An experimental test facility with a hydrogen-air combustor was designed and fabricated for this purpose to characterize a variety of packed beds for pressure drop and heat transfer. Flow through separate packed beds consisting of 9.5mm and 5mm steel spheres and lengths ~200mm and ~300mm were studied in the sphere based Reynolds numbers (Red) range of 0.4X104 to 8.5X104. The average porosity (є) of the randomly packed beds was ~0.4. The ratios of packed bed diameter to packing diameter for 9.5mm and 5mm sphere packing were ~ 9.5 and 18 respectively. The inlet flow temperature was unsteady and a suitable arrangement using mesh of spheres was used at either ends to eliminate flow entrance and exit effects. Stagnation pressures were measured at entry and exit of the packed beds. The pressure drop factor fpd, (ratio of Euler number (Eu) to packed bed dimensions) for packed bed with 9.5mm spheres exhibited an asymptotically decreasing trend with increasing Reynolds number, and a correlation for the pressure drop factor is proposed as, fpd=Eu/ [6(1-є) (L/dp)] =125.3 Red-0.4; 0.8X104 < Red < 8.5X104 (9.5mm sphere packing). However, for packed beds with 5mm spheres the pressure drop factor fpd, was observed to increase in the investigated Reynolds number range. The correlation based for pressure drop factor is proposed as, fpd= Eu/ [6(1-є) (L/dp)] =0.0479 Red0.37; 0.4X104 < Red < 3.9X104 (5mm sphere packing). The pressure drop factor was observed to be independent of the inlet flow temperature. Gas temperatures were measured at the entry, exit and at three axial locations along centerline in the packed beds. The solid packing temperature was measured at three axial locations in the packed bed. At Red~104, the influence of gas phase and solid phase thermal conductivity on heat transfer coefficient was found to be negligible based on order of magnitude analysis and solid packing temperature data obtained from the experiments. Evaluation of sphere based Nusselt number (Nud) at axial locations in the packed bed indicated a length effect on the heat transfer coefficient, which was a function of Reynolds number and size of spheres used in packing. The arithmetic average of Nusselt numbers at different axial locations in the packed bed were correlated as Nud=3.85 Red0.5; 0.5X104 < Red < 8.5X104. The Nusselt numbers obtained in the experiments were consistent with corresponding literature data available at lower Reynolds numbers. In this experimental study Euler number correlations for pressure drop and Nusselt number correlations for heat transfer were obtained for packed beds at Red~105. An engineering model for estimation of packed bed pressure and enthalpy drop was evolved, which is useful for sizing of packed bed heat exchanger in solid propellant gas generation systems.