Browsing by Author "da Silva, Alexandre K."

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    A detailed multi-component heat configuration assessment for complex industrial plants through Monte Carlo simulations: a case study for the cement industry
    (2025) Wolde Ponce, Ian; Starke, Allan R.; da Silva, Alexandre K.; Cardemil, José M.
    The decarbonization of industrial plants involves the integration of cleaner and more efficient energy processes, which might include electrification, renewable energy sources, waste heat recovery, and thermal energy storage. The technical viability of each assisting technology is usually assessed through direct simulations of the integrated system, which makes evaluation often difficult. This study proposes a methodology for estimating the heat demands of different configurations of a generic cement plant, aiming to assess the fuel consumption for the several integration cases considered. The waste heat and the mass flow rate of the internal streams are considered variable parameters, which lead to 32 distinct integration cases and 16,000 plant simulations. The operating conditions are generated through a Monte Carlo approach, ensuring the probability distribution of the results. The waste heat measures increase the plant’s heat demand and hinder its efficiency. A linear regression for fuel heat demand shows results ranging from 113.72MW to 492.62MW
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    A thermo-economical assessment of solar-based low-grade heat applied to the meat and dairy industries in Brazil
    (2024) Lemos, Leonardo F. L.; Starke, Allan R.; Cardemil, Jose M.; da Silva, Alexandre K.
    Solar heating for industrial processes (SHIP) is a promising alternative for heat generation worldwide, especially in industries where low-temperature heat is required. However, despite the large importance of the food industry in Brazil's gross domestic product, SHIP technology is still incipient. Among the reasons, one can mention high installation costs and the fact that many industries in Brazil already use affordable biomass as fuel for heat generation. Therefore, this work carries out a nationwide study of the technical and economic applicability of SHIP for hot water production in the Brazilian food industry, assessing the influence of several variables on SHIP systems profitability, such as the location of the food processing plant, the amount of heat it consumes, the size of the SHIP system installed for this plant, the costs of the solar heating system and of the replaced fuel. Results show that SHIP can be a profitable alternative to natural gas in any part of Brazil but can only compete with firewood in very specific locations, at very specific conditions. For instance, costs reductions around 20% for small SHIP systems allow them to compete with firewood for heat generation, while larger reductions (i.e., similar to 40%) would be beneficial for larger SHIP systems even when firewood costs are below 16 USD/MWh.
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    Geometric optimization of a solar tower receiver operating with supercritical CO2 as working fluid
    (2023) Emerick, Bruno S.; Battisti, Felipe G.; da Silva, Alexandre K.
    Concentrated solar power (CSP) plants represent a viable technology already operational in several locations worldwide. Among the numerous challenges associated with this technology, the proper design of the receiver is arguably one of the most critical. In that sense, the present study proposes using supercritical carbon dioxide (sCO2) as the working fluid for a cylindrical solar tower receiver. The receiver is modeled at steady state and considers a hybrid formulation that combines a 1-D model for the fluid flow and a 2-D CFD-based model for the conduction heat transfer process within the receiver walls. The analysis parametrically considers the number of plates composing the receiver and the number of channels in each plate, the s-CO2 mass flow rate, and the receiver aspect ratio as independent variables while focusing on the receiver's efficiency as the figure of merit. The analysis also considers two radiation boundary conditions over the receiver surface: (i) an idealized uniformly distributed heat flux and (ii) a real TMY-based spatially distributed radiation heat flux. As expected, the results indicate that the number of plates and the mass flow rate of the cooling fluid highly influence the receiver's efficiency. More interesting, however, is that by assuming a fixed external area for the receiver and parametrically varying the number of plates composing that receiver, it is possible to identify the design that maximizes the receiver's efficiency. The optimal number of plates changes with the receiver height, while the maximized efficiency is lightly sensitive to it. Furthermore, the analysis reveals that the appearance of a maximal value for the receiver's efficiency is associated with a competition between the radiation heat losses and the pumping expenditure needed to move the s-CO2 through the receiver.