<p dir="ltr">The chemical industry faces unprecedented pressure to reduce its carbon footprint while meeting growing global demand. As a major contributor to greenhouse gas emissions, accounting for approximately 7% of global carbon release, the sector plays a crucial role in achieving net-zero goals. This challenge is further compounded by projections suggesting that demand for chemicals could increase up to four-fold by 2050, and by the sector's role in producing several raw materials for other industries.</p><p dir="ltr">Within this context, endothermic reactors are of particular concern. The production of ethylene, propylene, and hydrogen alone accounts for around 3.6% of global CO2 emissions, representing over half of the chemical industry's total release. This situation underscores the need for alternatives in reactor design and operation.</p><p dir="ltr">To address these challenges, we introduce novel decarbonized process schemes and unit operations. The research centers around the development of Electric Reaction Towers (ERTs), a novel reactor configuration designed to ensure consistent product composition despite intense process fluctuations, such as those associated with Variable Renewable Energy (VRE). This is achieved by creating Custom Non-linear Heat Profiles (CNHPs) that maintain the key dimensionless groups of the system under dynamic conditions.</p><p dir="ltr">We present the concept of ERTs, explore their key principles, and the intuition behind their design. Additionally, we introduce Modular Reaction Towers (MRTs), which retain the benefits of handling fluctuations while addressing the investment and logistical challenges of adopting electric reactors.</p><p dir="ltr">The research employs a combination of Dimensional Analysis, Process Simulations, and Computational Fluid Dynamics (CFD) to evaluate these novel designs. Using ethylene production as a case study, we demonstrate that ERTs can enhance output by up to 4.2 times compared to state-of-the-art industrial designs.</p><p dir="ltr">The study further explores several additional concepts: Intermediate Cooling Zones (ICZs) and their potential to optimize complex reaction systems; the application of MRTs in the decentralized production of liquid hydrocarbons from shale gas to reduce flaring; and TurboQuenching, a novel approach to rapidly cool reaction products without a cooling agent while co-producing power. Finally, we discuss the broader implications of these innovations for the chemical industry's transition to more sustainable and efficient production methods.</p><p dir="ltr">By fundamentally re-thinking reactor design, this research contributes to the development of more efficient and sustainable production methods in the chemical industry, supporting the transition to a Net-Zero future.</p><p><br></p>

<p dir="ltr">Managing transient heat loads has become more challenging with the increasing electrification of ground, air, and marine vehicles. Doing so requires novel designs of thermal management systems, or in some cases, novel retrofits of legacy TMSs to accommodate the addition of more electrified subsystems. However, design tools that are well suited for examining and optimizing the dynamic response of TMS over candidate operation or mission profiles are limited. In this thesis, a principled methodology and associated tools for the enumeration and dynamic optimization of all feasible architectures of an air cycle machine are presented. Graph-based modeling is pivotal for exploring and optimizing ACM architectures, providing a structured representation of system components and interactions. By modeling the ACM as a graph, with vertices and edges representing components and interactions, respectively, various component configurations and performance metrics can be systematically analyzed. This approach enables efficient exploration of design alternatives and consideration of dynamic boundary conditions (representing, for example, a complex mission profile) during optimization. Another unique contribution of this thesis is a novel application of a multi-state graph-based modeling approach for developing dynamic models of turbomachinery components. By representing multiple states within each control volume or component and connecting them through power flows, this approach accurately captures both first and second law dynamics, enabling the computation of dynamic entropy generation rates. A detailed case study demonstrates the optimization of ACM architectures based on entropy generation minimization and dynamic bleed air flow rate minimization. This study highlights the trade-offs between different optimization criteria and the potential for generalizing the tool to more complex thermofluid systems in thermal management applications. The results underscore the importance of entropy-based analysis in comparing the thermodynamic losses across various system architectures.</p>

<p>The ongoing and rapidly accelerating integration of inverter-based resources (IBRs), such as solar panels, into power distribution systems has heightened the importance of computational tools that can be used to study the dynamics of such systems. IBRs use power electronics to interface the energy sources to the grid, thereby introducing faster dynamics than their electromechanical counterparts, which could lead to instabilities in distribution systems and microgrids. Hence, there is a need for conducting simulations of distribution systems containing large numbers of single- and three-phase inverters, which could be operating under either grid-following or grid-forming modes.</p> <p>A key objective of this thesis is to derive detailed, high-fidelity models of inverters and their controls in the context of unbalanced distribution networks. In addition, a diesel synchronous generator model is derived, for the sake of completeness. The main contribution of this work is that these models are developed for use in a novel simulation toolbox called Dynamic Simulation Tool using a Sparse Tableau Approach in Python, DynaSTPy (pronounced dynasty). This thesis outlines how the components can be modeled in the sparse tableau framework as electrical networks with topology described using a node-branch incidence matrix. In addition, the thesis explains how controller dynamics and constraints can be handled within this framework. These models are tailored to seamlessly integrate into the DynaSTPy toolbox. The proposed approach can be readily extended to model other such components in the future.</p>

<div> <div> <div> <p>Organic-inorganic halide perovskite solar cells have increased efficiencies substantially (from 3% to > 22%), within a few years. However, these solar cells degrade very rapidly due to humidity and no longer are capable of converting photons into electrons. Methylammonium Lead Triiodide (CH3NH3PbI3 or MAPbI3) is the most common type of halide perovskite solar cell and is the crystal studied in this thesis. Graphene is an effective encapsulation method of MAPbI3 perovskite to reduce degradation, while also being advantageous because of its excellent optical and conductive properties. Using a PMMA transfer method graphene was chemical vapor depostion (CVD) grown graphene was transferred onto MAPbI3 and reduced the MAPbI3 degradation rate by over 400%. The PMMA transfer method in this study is scalable for roll-to- roll manufacturing with fewer cracks, impurites, and folds improving upon dry transfer methods. To characterize degradation a fluorescent microscope was used to capture photoluminescence data at initial creation of the samples up to 528 hours of 80% humidity exposure. Atomic force microscopy was used to characterize topographical changes during degradation. The study proves that CVD graphene is an effective encapsulation method for reducing degradation of MAPbI3 due to humidity and retained 95.3% of its initial PL intensity after 384 hours of 80% humidity exposure. Furthermore, after 216 hours of 80% humidity exposure CVD graphene encapsulated MAPbI3 retained 80.2% of its initial number of peaks, and only saw a 35.1% increase in surface height. Comparatively, pristine MAPbI3 only retained 16% of its initial number of peaks and saw a 159% increase in surface height. </p> </div> </div> </div>

Despite the central importance of porous electrodes to any advanced electrochemical system, there is no clear answer to “<i>How to make the best electrode</i>?”. The source of ambiguity lies in the incomplete understanding of convoluted material interactions at smaller – difficult to observe length and timescales. Such mesoscopic interactions, however, abide by the fundamental physical principles such as mass conservation. The porous electrodes are investigated in such a physics-based setting to comprehend the interplay among structural arrangement and off-equilibrium processes. As a result, a synergistic approach exploiting the complementary characteristics of controlled experiments and theoretical analysis emerges to allow mechanistic insights into the associated mesoscopic phenomena. The potential of this philosophy is presented by investigating three distinct electrochemical systems with their unique peculiarities.

Encontrar soluções para a problemática dos resíduos e, em virtude da crescente demanda por energia, diminuir a dependência dos combustíveis fósseis têm constituído grandes desafios para os pesquisadores. O setor hospitalar é um potencial gerador dos chamados Resíduos de Serviços de Saúde (RSS) que também apresenta um alto consumo de energia em decorrência do seu período de funcionamento e de equipamentos que necessitam de infraestrutura adequada. Apesar de representarem uma pequena parcela perante o montante dos Resíduos Sólidos Urbanos (RSU), no Brasil, nem todos os geradores se preocupam com seu tratamento e destinação final. O emprego de tecnologias desenvolvidas para o tratamento desses resíduos com a possibilidade de recuperação energética deve ser avaliado. O Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto (HC-FMRP-USP) gera cerca de 1,9 ton/dia de RSS. Nesse contexto, o objetivo geral desta pesquisa foi avaliar a viabilidade legal, ambiental e econômico-financeira da implantação de um sistema próprio de tratamento de RSS no HCFMRP- USP para geração de energia. A metodologia foi estruturada em pesquisa exploratória, coleta de dados por meio de entrevistas semi-estruturadas com responsáveis pelo setor dos RSS no hospital, com pesquisadores da área da saúde, de escolas de engenharia, órgãos técnicos e indústrias fabricantes dos equipamentos; levantamento bibliográfico e análise de conteúdo. Para a avaliação econômico-financeira, foi empregada a avaliação custoefetividade. Estudos comparativos sobre os tipos de tratamento disponíveis e utilizados nacionalmente foram considerados. Assim, o processo que melhor se adequou ao sistema proposto foi o da incineração com tecnologia de gaseificação e combustão combinadas (GCC). Os resultados demonstraram que o sistema proposto está sob a égide da lei contemplando, inclusive, a Política Nacional de Resíduos Sólidos (PNRS), desde que mediante anuência do Conselho Gestor do campus da USP e de sua Comissão de Meio Ambiente, além do devido processo de licenciamento ambiental junto à CETESB e pré-análise dos RSS. Contudo, sob o aspecto ambiental há questões públicas e políticas sobre a aceitação de sua implantação no complexo hospitalar. Embora haja o emprego de avançada tecnologia, o equipamento avaliado necessita de instalação, manutenção e monitoramento adequados por profissionais capacitados para operá-los, a fim de se evitar possíveis danos às pessoas e ao meio-ambiente, para isso, os envolvidos devem agir com responsabilidade. Por fim, sob o aspecto econômico-financeiro houve um empate técnico entre os custos do tratamento realizado atualmente e os da proposta do investimento. Assim, esse último aspecto avaliado incidiu sobre o benefício implícito da decisão de se implantar ou não o processo. Portanto, considera-se a viabilidade da implantação de um sistema próprio para tratamento de RSS no HCFMRP-USP para geração de energia sob os três aspectos: legal, ambiental e econômicofinanceiro. / Finding solutions to the waste problem and reducing dependence on fossil fuels due to the growing demand for energy have become big challenges for researchers to deal with. Hospitals are large producers of Medical waste (MW) and also big energy consumers due to their long running hours and the running of equipment that demands adequate infrastructure. Despite accounting for a small share of all the Municipal Solid Waste (MSW) not all producers, in Brazil, are concerned about waste treatment and its final destination. The use of technologies developed with the aim of treating such waste in order to generate energy has to be assessed. The Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto (HCFMRP-USP) generates around 1.9 tons of waste per day. In this context, the general aim of this research program was to assess the legal, environmental and economic-financial feasibility of the implementation of a private system of biomedical waste treatment at HCFMRP-USP in order to generate energy. The method was structured in exploratory research, data gathering by means of semi-structured interviews with MW department staff at the hospital, with Health researchers, with Engineering College researchers, technical organizations and equipment manufacturers, besides bibliographic referencing and content analysis. Cost-effectiveness analysis was used for the economic-financial analysis. Comparative studies of the types of treatment available and used nationwide were taken into consideration. Thus, the process which best suited the proposed system was that of incineration by means of Gasification Combined Cycle (GCC). Results showed that the proposed system is under the support of Law and it also takes into consideration the National Policy for Solid Waste (NPSW), provided that it has the approval of the Director Council of the Administration of the campus of USP and of its Environment Committee as well as appropriate environmental licenses granted by CETESB and pre-analysis of MW. However, under the environmental aspect, there are public and political issues regarding the acceptance of this implementation in the hospital premises. Although there is the use of advanced technology, the equipment which was assessed needs to be installed, maintained and monitored adequately by professionals trained to operate it so as to avoid possible damage to humans and the environment. Staff involved must be responsible. Finally, under the economic-financial aspect there was a draw between the costs of the treatment conducted at present and those of the proposed investment. Therefore, this last aspect assessed prevailed over the implicit benefit of the decision on whether to implement the process or not. However, the feasibility of the implementation of a private MW treatment system at HC-FMRP-USP in order to generate energy is to be considered under the legal, environmental and economicfinancial aspects.

Submitted by Maria Aparecida (cidazen@gmail.com) on 2017-08-29T13:12:16Z No. of bitstreams: 1 Tiago Silva.pdf: 3175763 bytes, checksum: 8eba0f17a1a1f6fa2606a5235969987e (MD5) / Made available in DSpace on 2017-08-29T13:12:16Z (GMT). No. of bitstreams: 1 Tiago Silva.pdf: 3175763 bytes, checksum: 8eba0f17a1a1f6fa2606a5235969987e (MD5) Previous issue date: 2012-11-09 / CNPQ / The Distributed Generation (DG) can improve the power quality indices associated with Short Duration Voltage Variations (SDVV) due to the reduction in the electric network loading, which in turn causes an improvement in the pre-fault voltage profile. On the other hand, the DG can also deteriorates the power quality indices related to SDVV due to the increasing in the fault currents, which in turns reduce the post-fault voltages. Furthermore, the assessment of the DG impact on SDVV is more difficult with the presence of renewable energy resources. This complexity is due to fluctuations in output power caused by stochastic variations in the primary energy source (sun, wind, tide levels, etc.). Additionally, the bibliographical review on Predictive Assessment of Short Duration Voltage Variations (PAVV) revealed that none of the existing methodology considered the impact of fluctuations in the output power of a wind DG on power quality indices related to SDVV. It was also noticed that the load variations during the study period are ignored in the papers on SDVV. The existence of these deficiencies and the governmental incentives for the use of wind generation motivated this research. The main aim of this dissertation is the development of a methodology for the PAVV capable of recognizing uncertainties associated with wind DG and load fluctuations. The modeling of these uncertainties was carried out using NonSequential Monte Carlo Simulation (MCS). The nodal voltages in the fault scenarios generated by MCS were evaluated using the Admittance Summation Method (ASM) in phase coordinates. The combination of the MCS with the ASM allowed estimating the following indices related to SDVV: the expected value of the SARFI (“System Average RMS – Variation – Frequency Index”) and expected nodal frequency of SDVV. Furthermore, the probability distributions and box plots of the SARFI index have been obtained. The proposed method for the PAVV was tested and validated in a test system with 32 buses. The tests results demonstrated that the DG insertion causes an improvement in the power quality indices associated with SDVV. Additionally, the substitution of conventional DG by wind DG cause a small deterioration in the power quality indices related to SDVV due to fluctuations in the output power of the wind DG. Finally, it was observed that the load fluctuations during the study period cause significant variations in the SARFI index. / A Geração Distribuída (GD) pode melhorar os índices de qualidade de energia associados com as Variações de Tensão de Curta Duração (VTCD) devido a redução no carregamento da rede elétrica, que por sua vez causa uma melhoria no perfil de tensão pré- falta. Por outro lado, a GD também pode degradar os índices de qualidade de energia associados com VTCD devido ao aumento nas correntes de falta, que por sua vez reduzem as tensões pós-falta. Além disso, a avaliação do impacto da DG sobre VTCD é mais difícil com a presença de fontes de energia renováveis. Esta complexidade se deve as flutuações na potência de saída causadas pelas variações estocásticas na fonte de energia primária (sol, vento, níveis de maré, etc.). Adicionalmente, a revisão bibliográfica realizada sobre Avaliação Preditiva de VTCD (APVT) revelou que nenhuma metodologia existente considerou o impacto de flutuações na potência de saída de geradores eólicos nos índices de qualidade referentes às VTCD. Também foi observado que flutuações de carga ao longo do período de estudo são desconsideradas nos artigos sobre APVT. A existência destas deficiências nos métodos de APVT e os incentivos governamentais para o uso de geração eólica motivaram esta pesquisa. O principal objetivo desta dissertação é o desenvolvimento de uma metodologia para a APVT capaz de reconhecer as incertezas associadas com a GD eólica e flutuações de carga. A modelagem destas incertezas na APVT foi realizada através do uso da Simulação Monte Carlo (SMC) não-sequencial. As tensões nodais nos cenários de falta gerados pela Simulação Monte Carlo (SMC) foram calculadas usando-se o Método de Soma de Admitância (MSA) em coordenadas de fase. A combinação da SMC com o MSA permitiu estimar os seguintes índices probabilísticos relacionados com as VTCD: valor esperado do SARFI (“System Average RMS – Variation – Frequency Index”) e frequência nodal esperada de VTCD. Além disso, foram obtidas distribuições de probabilidade e diagramas de caixa associados com o SARFI. O método proposto nesta dissertação para a APVT foi testado em uma rede de distribuição de 32 barras. Os resultados dos testes mostram que a inserção de GD causa uma melhoria nos índices de qualidade associados com as VTCD. Adicionalmente, a substituição de GD convencional por GD eólica causa uma pequena deterioração nos índices de qualidade referentes às VTCD devido as flutuações na potência de saída da GD eólica. Finalmente, também foi observado que as flutuações na carga ao longo do período de estudo causam variações significativas no índice SARFI.

The North American forest industry has long been an important part of North America’s economy. The industry has traditionally been the only industrial demand on timberland creating a long established balance between the supply (timberland) and the demand (manufacturing). Recently the forest industry has been troubled due to the collapse of the solid wood products largest market, housing, and a global recession. These troubled times have lead many operation in the industry to curtail operations. Since the industry curtailed, high oil prices and increasing environmental concern have advocated the investment in renewable energy sources. As a renewable energy source, biomass holds great potential for satisfying a portion of our continental energy demands. This increased demand for timberland products could be very profitable to the timberland owners but also holds many concerns to the extent of additional supply that can be harvested from our timberlands. Further complicating the balance of supply and demand are the large global and domestic effects that are reducing the total amount of timberland and increasing the demand for the remaining timberlands. The supply and demand changes have the potential to make the forest industry evermore important part of the North American economy but care must be taken to not over extend our resources.

Made available in DSpace on 2014-12-17T14:56:16Z (GMT). No. of bitstreams: 1 AugustoCFW_DISSERT.pdf: 4069800 bytes, checksum: c488b0f09f064b7a5254eca8a4fff499 (MD5) Previous issue date: 2013-08-30 / The generation of electricity in Brazil is predominantly renewable, with internal hydraulic generation being more than 70% of its energy matrix. The electricity rationing occurred in 2001 due to lack of rain, led the country to increase the participation of alternative energy sources. This need for new sources of energy makes the regional potential to be exploited, which configures the change of generation model from centralized generation to distributed generation. Among the alternative sources of energy, the solar energy is presented as very promising for Brazil, given that most of its territory is located near to the equator line, which implies days with greater number of hours of solar radiation. The state of Rio Grande do Norte (RN) has one of the highest levels of solar irradiation of the Brazilian territory, making it eligible to receive investments for the installation of photovoltaic solar plants. This thesis will present the state-of-the-art in solar photovoltaic power generation and will examine the potential for generation of solar photovoltaic power in Brazil and RN, based on solarimetrics measurements conducted by various institutions and also measurements performed in Natal, the state capital / A gera??o de energia el?trica no Brasil ? predominantemente renov?vel, com a gera??o interna hidr?ulica sendo superior a 70% do total de sua matriz energ?tica. O racionamento de energia el?trica ocorrido em 2001, devido ? falta de chuvas, levou o pa?s a incrementar a participa??o de fontes alternativas de energia. Esta necessidade por novas fontes de energia faz com que as potencialidades regionais sejam aproveitadas, o que configura a mudan?a do modelo de gera??o, passando de gera??o centralizada para gera??o distribu?da. Dentre as fontes alternativas de energia, a solar apresenta-se como uma fonte bastante promissora para o Brasil, tendo em vista que a maior parte do seu territ?rio est? localizada pr?ximo ? linha do equador, o que implica em dias com maior quantidade de horas de radia??o solar. O Estado do Rio Grande do Norte (RN) tem um dos maiores ?ndices de incid?ncia solar do territ?rio brasileiro, o que o torna apto a receber investimentos para a instala??o de usinas solares fotovoltaicas. Esta disserta??o apresentar? o estado da arte em gera??o de energia solar fotovoltaica e analisar? o potencial de gera??o da energia solar fotovoltaica no Brasil e no RN, baseando-se em medi??es solarim?tricas realizadas por diversas institui??es e tamb?m em medi??es realizadas em Natal

Made available in DSpace on 2014-07-29T12:05:39Z (GMT). No. of bitstreams: 1 tese ana.pdf: 3317264 bytes, checksum: 1b832f28771563b1839c5af29d886623 (MD5) Previous issue date: 2008-09-11 / Este trabalho apresenta o desenvolvimento de uma modelagem para inserção de restrição de qualidade de água ao planejamento da operação de sistemas hidrotérmicos de longo prazo. Considerar a qualidade da água no planejamento garante, o enfoque do uso múltiplo da água. O objetivo deste é explorar a sensibilidade do planejamento de sistemas hidrotérmicos à inserção de uma variável ambiental, focando a qualidade da água. Dentre os indicadores de qualidade da água, a escolha foi pela clorofila-a e aporte de fósforo estabelecendo uma relação com o volume do reservatório. / Este trabalho apresenta o desenvolvimento de uma modelagem para inserção de restrição de qualidade de água ao planejamento da operação de sistemas hidrotérmicos de longo prazo. Considerar a qualidade da água no planejamento garante, o enfoque do uso múltiplo da água. O objetivo deste é explorar a sensibilidade do planejamento de sistemas hidrotérmicos à inserção de uma variável ambiental, focando a qualidade da água. Dentre os indicadores de qualidade da água, a escolha foi pela clorofila-a e aporte de fósforo estabelecendo uma relação com o volume do reservatório.