DSpace Collection:http://hdl.handle.net/10174/144232024-03-04T08:51:50Z2024-03-04T08:51:50ZNew plant communities to define the southern boundary of the European Atlantic Province in mainland PortugalRaposo, Maurodel Río, SaraVázquez-Pardo, FranciscoCosta, José CarlosCano-Ortiz, AnaPinto-Gomes, Carloshttp://hdl.handle.net/10174/361792024-01-23T11:13:57Z2023-11-01T00:00:00ZTitle: New plant communities to define the southern boundary of the European Atlantic Province in mainland Portugal
Authors: Raposo, Mauro; del Río, Sara; Vázquez-Pardo, Francisco; Costa, José Carlos; Cano-Ortiz, Ana; Pinto-Gomes, Carlos
Abstract: This study identifies and analyzes the plant communities that allow the definition of the geographic limits between Temperate and Mediterranean macrobioclimates, for the center of Portuguese mainland. The altitude of Serra da Estrela, Açor and Lousã, combined with the increase in atmospheric humidity, allows the presence of vegetation typical of a Temperate macrobioclimate. Thus, based on the phytosociological methodology, floristic relevés were carried out in order to identify the series of vegetation existing in these territories. Through these relevés carried out, four new plant associations were identified: Cytisetum grandifloro-striati ass. nova, Scrophulario grandiflorae-Sambucetum nigrae ass. nova, Pruno lusitanicae-Coryletum avellanae ass. nova that lives in the submediterranean bioclimatic variant, mesotemperate humid to hyper-humid. A new association namely Genisto falcatae-Quercetum broteroanae ass. nova with two subassociations were also identified. Based on the vegetation distribution, new biogeographic limits are proposed. Thus, it was intended to identify the southern limits of the European Atlantic Province (Atlantic Orolusitania Subrovince) based on the vegetation cover, namely the distinction between the Estrela Sierran District and a new Biogeographical District, the Alvo-Gardunhense.2023-11-01T00:00:00ZSimulation of a Thermal Recuperative Incinerator of VOCs with a Special Focus on the Heat ExchangerZdanowski, FranciscoMalico, IsabelCanhoto, PauloLima, Rui Pedrohttp://hdl.handle.net/10174/358572024-01-08T11:26:23Z2024-02-01T00:00:00ZTitle: Simulation of a Thermal Recuperative Incinerator of VOCs with a Special Focus on the Heat Exchanger
Authors: Zdanowski, Francisco; Malico, Isabel; Canhoto, Paulo; Lima, Rui Pedro
Abstract: Simulation and modeling of thermal recuperative incinerators may play an important role in enhancing efficiency and ensuring compliance with environmental regulations. In this context, the primary objective of this study is to simulate and comprehensively understand the operation of a geometrically complex thermal recuperative incinerator with an integrated preheater featuring varying levels of heat recovery. To achieve this objective, a simple yet effective 0D model was developed. This modeling approach allows for a holistic evaluation of the performance of the incinerator, enabling the assessment of key parameters, such as temperatures and heat transfer rates, under varying operating conditions. Successful validation of the model is established by comparing its results with measurements from an industrial thermal recuperative incinerator in operation at a vehicle assembly plant, with maximum relative differences of around 9%. Simulations for different percentages of flue gases bypassing the preheater were conducted, indicating a good compromise between heat transfer and pressure drop and a 22% heat recovery at around 50%. The model presented in this paper provides a robust foundation for comprehensively assessing and optimizing the performance of thermal recuperative incinerators and systems that comprise thermal recuperative incinerators, with implications for waste management and sustainable energy recovery systems.2024-02-01T00:00:00ZCFD Analysis of Perforated Plates and Open-Cell Materials AerodynamicsAntonio, F. Miguelhttp://hdl.handle.net/10174/358072023-12-20T11:11:37Z2023-01-01T00:00:00ZTitle: CFD Analysis of Perforated Plates and Open-Cell Materials Aerodynamics
Authors: Antonio, F. Miguel
Abstract: In this paper, a numerical study of fluid flow through perforated panels with square holes and open-cell material with cubic cells is presented. Structures with a wide variety of porosities (0.15<E<0.94) and Reynolds numbers (0.01<Re<6000) are studied. Among the various outcomes obtained, the results indicate that pressure gradient vs Reynolds number exhibits three different forms of variation, including linear (Re<1), nonlinear (1≤Re<4000), and one where the pressure gradient is virtually constant with the Reynolds number (Re≥4000). The results were provided in terms of loss factor, but also of intrinsic permeability and the Forchheimer coefficient. Relationships that connect porosity to the loss factor, intrinsic permeability, and Forchheimer coefficient are also presented. These findings may prove useful in better understanding the flow behaviors in perforated panels and cell metal foams, which have a wide range of applications.2023-01-01T00:00:00ZPrediction of circumsolar irradiance and its impact on CSP systems under clear skiesAbreu, Edgar F.M.Canhoto, PauloCosta, Maria Joãohttp://hdl.handle.net/10174/357822023-12-12T14:26:02Z2023-12-07T00:00:00ZTitle: Prediction of circumsolar irradiance and its impact on CSP systems under clear skies
Authors: Abreu, Edgar F.M.; Canhoto, Paulo; Costa, Maria João
Abstract: In this work, a model to estimate circumsolar normal irradiance (CSNI) for several half-opening angles under clear skies was developed. This approach used a look-up table to determine the model parameters and estimate CSNI for half-opening angles between 0.5° and 5°. To develop and validate the proposed model, data from five locations worldwide were used. It was found that the proposed model performs better at the locations under study than the models available in the literature, with relative mean bias error ranging from −13.94% to 0.70%. The impact of CSNI for these different half-opening angles on concentrating solar power (CSP) systems was also studied. It was found that neglecting CSNI could lead to up to a 7% difference between the direct normal irradiance (DNI) measured by a field pyrheliometer and the DNI that is captured by CSP systems. Additionally, a case study for parabolic trough concentrators was performed as a way to estimate the impact of higher circumsolar ratios (CSR) on the decrease of the intercept factor for these systems. It was also concluded that if parabolic trough designers aim to reduce the impact of CSNI variation on the intercept factor, then parabolic troughs with higher rim angles are preferred.2023-12-07T00:00:00Z