Browsing by Author "Cardemil, Jose M."

Now showing 1 - 7 of 7
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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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    Application of layer view factor method in high temperature thermal storage packed bed
    (2024) Cortes, Eduardo; Gavino, David; Calderon-Vasquez, Ignacio; Garcia, Jesus; Estay, Danilo; Cardemil, Jose M.; Barraza, Rodrigo
    This study provides a comprehensive evaluation of radiation effects on the thermal behavior of a packed bed using a discrete model for heat transfers integrating a novel method called Layer View Factor for view factors estimation, which significantly decreases computational time by less than 9000 times compared to the parallel ray tracing method. The model is validated and strongly aligned with experimental data at 823 K, with a maximum mean bias and root mean square errors of +/- 4.5 K and 10 K, respectively. Analyses of temperature profiles and thermocline lengths for charging, discharging, and stand-by processes at a charge temperature of 1473 K were performed, finding a thermal flattening effect with radiation, leading to lower peak temperatures and quicker thermocline length evolutions. Notably, the stand-by process exhibited the largest impact, with a maximum temperature difference of up to 100 K compared to the non-radiation case. Moreover, analysis of the temperature and energy of discharge found that the maximum discharge temperature drops below 90% of the charge temperature when radiation is included. Finally, efficiency analysis of the processes showed differences of up to 2% between having or not the radiation effect, aiming its role as a redistribution mechanism in the packed bed's temperature.
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    Design and assessment of a concentrating solar thermal system for industrial process heat with a copper slag packed-bed thermal energy storage
    (2024) David-Hernandez, Marco A.; Calderon-Vasquez, Ignacio; Battisti, Felipe G.; Cardemil, Jose M.; Cazorla-Marin, Antonio
    Decarbonising the industrial sector is a key part of climate change mitigation targets, and Solar Heat for Industrial Process (SHIP) is a promising technology to achieve this. However, one of the drawbacks of SHIP systems is that they rely on an intermittent energy source. Therefore, sensible energy storage has emerged as a potential solution. In addition, solid byproducts have been proposed as a low-cost but effective material for thermal energy storage (TES). This work presents a SHIP system model coupled with a copper slag-packed-bed TES (PBTES) model using air as heat transfer fluid. The TES has been implemented to preheat the makeup water of the tank where steam is generated. A system design was carried out using a parametric analysis to find a solar field size and a corresponding TES volume. The resulting system was simulated, and the operating variables were analysed in detail. The results show that it is possible to generate 20% more energy due to the storage system. Additionally, a techno-economic analysis indicates that the SHIP with PBTES system results in a payback period of 14 years and a savings of CO2 emissions of 30 t CO2.
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    Exergy cost and thermoeconomic analysis of a Rankine Cycle plus Multi-Effect Distillation plant considering time-varying conditions
    (2019) Mata-Torres, Carlos; Zurita, Adriana; Cardemil, Jose M.; Escobar, Rodrigo A.
    A detailed exergy cost and thermoeconomic analysis applied to a Rankine Cycle (RC) coupled to a Multi-Effect Distillation (MED) plant was performed. The aim of this work is to identify the impact of design and operating conditions on the exergy and thermoeconomic costs of the final products, electricity, and freshwater, and to assess the distribution of the destroyed exergy, the fuel, and the plant costs. The plant model considers a high disaggregation model, which includes MED plant and condenser parasitic losses, a seawater pumping system and a brine energy recovery system. It also considers solar molten salts as the RC fuel, which is the typical fluid used in solar tower plants. The impact of RC + MED plant part-load operation, ambient temperature, MED plant size, and location plant's altitude was evaluated and an analysis of operational day of the RC + MED plant was carried out. Results indicate that the plant part-load operation has a significant influence on the unit exergy and thermoeconomic product costs, while the ambient temperature evidences only a minor effect on the water costs. As well, the largest MED plant sizes (above 50,000 m(3)/day) offer the lowest electric and water costs, while the altitude strongly increases the water costs.
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    On the analytical solution of the one-dimensional convection-conduction equation for packed-bed thermal energy storage systems
    (2024) Calderon-Vasquez, Ignacio; Battisti, F. G.; Rosales-Vera, Marco; Cardemil, Jose M.; Escobar, Rodrigo
    Temperature distribution modeling within packed-bed thermal energy storage (PBTES) systems is crucial to simulate its integration into heat sources and perform techno-economic analyses to assess the actual benefits associated with its use. This article proposes a one-dimensional convection-conduction equation to model a fluid-solid system by assuming volume-averaged properties for the energy balance and determines the analytic solution through Integral Transforms. The present study analyzes the applicability of this analytic solution considering different operational conditions of PBTES systems. The article revealed that the P & eacute;clet number (Pe) and the fluid-to-solid capacity ratio (kappa) must be limited to obtain stable solutions, while the dimensionless time tau cannot be arbitrary despite computing an analytic solution. A sensitivity study of the solution for parameter a=kappa Pe/2 defined the minimum dimensionless time required for the solution to be stable. This stability was assessed with existing experimental setups, indicating the solution's feasibility for air-solid PBTES systems.
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    Techno-economic analysis of hybrid solar thermal systems with flat plate and parabolic trough collectors in industrial applications
    (2024) Rosales-Perez, Josue F.; Villarruel-Jaramillo, Andres; Perez-Garcia, Manuel; Cardemil, Jose M.; Escobar, Rodrigo
    Hybrid configurations that combine two different solar thermal collector technologies are considered to improve the economic competitiveness of solar systems in district heating applications. However, the performance of these systems in the industrial sector has been scarcely studied. This study evaluates the energetic and economic potential of hybrid systems with flat plate and parabolic trough collectors under different industrial process temperatures and radiation levels. To enable this evaluation, a hybrid field sizing methodology was developed. The results showed that the hybrid system could achieve high solar fractions with a lower levelized cost of heat than parabolic trough collector individual systems and smaller solar field areas than flat plate collector individual systems. Furthermore, the hybrid system with approximately 50% flat plate collectors reached monthly solar fractions up to 91% higher than the individual flat plate collector alternative. The seasonal performance demonstrates that the hybrid configuration could have great potential for applications with higher demand in the summer months, such as solar cooling with absorption chillers and solar water desalination for crop irrigation. This study contributes to the understanding of the potential of hybrid systems in the industrial sector and presents tools and insights for future research of hybrid solar thermal configurations.
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    Transient modeling of stratified thermal storage tanks: Comparison of 1D models and the Advanced Flowrate Distribution method
    (2024) Riebel, Adrian; Wolde, Ian; Escobar, Rodrigo; Barraza, Rodrigo; Cardemil, Jose M.
    Thermal energy storage (TES) is one of the key technologies for enabling a higher deployment of renewable energy. In this context, the present study analyzes the modeling strategies of one of the most common TES systems: stratified thermal storage tanks. These systems are essential to many solar thermal installations and heat pumps, among other clean energy technologies. Three different one-dimensional tank models are compared by their computing speed and resilience to long time steps. Two of the models analyzed are numerical, one being explicit and the other one implicit, and the other is analytical. The models are validated against data from experiments carried out considering small-scale stratified tanks, showing that their performance can be improved by using the Advanced Flowrate Distribution (AFD) method. The results show that the analytical model maintains its accuracy with longer time steps and is robust against divergence. Conversely, the numerical models show equivalent performance for short time steps, while the computation time is reduced. Although the AFD method shows promising results by achieving an improvement of 43% in terms of Dynamic Time Warping, its parameter optimization must be generalized for different tank designs, flow rates, and temperatures.