DSpace Angular :: Browsing by Author "Escobar, Rodrigo"

Browsing by Author "Escobar, Rodrigo"

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Advances in aerosol optical depth evaluation from broadband direct normal irradiance measurements
(2021) Salmon, Alois; Quinones, Gonzalo; Soto, Gonzalo; Polo, Jesus; Gueymard, Christian; Ibarra, Mercedes; Cardemil, Jose; Escobar, Rodrigo; Marzo, Aitor
Aerosols are part of the attenuation processes that impact solar radiation within the atmosphere. They influence the availability and spectrum of the solar resource for each location at the earth's surface. The present study presents advances in the development of a methodology intended to estimate the aerosol optical depth (AOD) at a given location from broadband direct normal irradiance (DNI) measurements and an appropriate radiative transfer model (RTM) operated backwards. For this purpose, databases provided by AERONET and BSRN at 16 stations throughout the world are jointly employed as inputs to the proposed methodology. The validation of two RTMs (SMARTS and SOLIS) is first undertaken to estimate DNI under clear-sky conditions at each station, assuming both AOD and additional atmospheric inputs are known from sunphotometric measurements. Results indicate that both models achieve good performance, characterized by a relative rRMSE of 3.2% for SMARTS and 3.8% for SOLIS. In the second, and most important stage, the AOD at 550 nm (AOD550) is derived using these models again, but in an iterative mode, now using the 1-minute DNI measurements as inputs. Periods of clear line of sight to the sun first need to be selected from the irradiance measurement record. This, along with other difficulties, make this operation prone to errors when only DNI measurements are available. In spite of this, the results show that AOD can be estimated with a 16-site average mean bias error of only between -0.024 and 0.015 AOD unit and an absolute RMSE between 0.025 and 0.050 AOD unit (compared to the AERONET ground truth), depending on model. Notable improvements are obtained if secondary atmospheric variables are extracted from the MERRA-2 reanalysis and are included as inputs for local computations. The present results suggest that the method is able to compare favorably with AOD estimates from MERRA-2 predictions or MODIS observations, for instance.
An in-depth system-level assessment of green hydrogen production by coupling solid oxide electrolysis and solar thermal systems
(2025) Arias, Ignacio; Castillejo Cuberos, Armando; Battisti, Felipe G.; Romero Ramos, J.A.; Pérez, Manuel; González Portillo, L.F.; Valenzuela, Loreto; Cardemil Iglesias, José Miguel; Escobar, Rodrigo
This study presents a comprehensive techno-economic analysis of green hydrogen production utilizing a third-generation Concentrated Solar Power system integrated with Solid Oxide Electrolysis Cells, examining system configurations under variable climatic conditions in Chile and Spain. By employing dynamic simulation models that consider hourly and sub-hourly datasets, the research assesses the impact of solar irradiance variability on hydrogen production efficiency. The integration approach explores the efficacy of utilizing high-temperature solar power-derived heat for enhanced electrolysis operation, highlighting the critical influence of solar resource quality and data temporal resolution in system performance. Several scenarios involving different solar multiples, thermal energy storage capacities, and electrolyzer sizes were analyzed to identify their effects on the Levelized Cost of Hydrogen. The economic analysis reveals that this cost is notably sensitive to operational parameters and system configurations, suggesting that optimal integration and scaling of solar power and electrolysis technologies could significantly reduce hydrogen production costs. The findings underscore the need for targeted energy policies and investments in renewable technologies to support cost-effective hydrogen production, promoting future research focusing on advanced materials for electrolysis cells and improved system integration strategies. This work enhances the understanding of integrating advanced solar thermal and electrolysis technologies, providing a robust framework for advancing global sustainable energy solutions.
Comparison of the levelized cost and thermoeconomic methodologies - Cost allocation in a solar polygeneration plant to produce power, desalted water, cooling and process heat
(2018) Leiva-Illanes, Roberto; Escobar, Rodrigo; Cardemil Iglesias, José Miguel; Alarcon-Padilla, Diego-Cesar
Dense transient pinches and pulsed power technology: research and applications using medium and small devices
(2008) Soto, Leopoldo; Pavez, Cristian; Moreno, Jose; Cardenas, Miguel; Tarifeno, Ariel; Silva, Patricio; Zambra, Marcelo; Huerta, Luis; Tenreiro, Claudio; Giordano, Jose Luis; Lagos, Miguel; Retamal, Cesar; Escobar, Rodrigo; Ramos Grez, Jorge; Altamirano, Luis
Evolution of corrosion products on ASTM A36 and AISI 304L steels formed in exposure to molten NaNO₃-KNO₃ eutectic salt: Electrochemical study
(2022) Pineda, Fabiola; Walczak, Magdalena; Vilchez, Franco; Guerra, Carolina; Escobar, Rodrigo; Sancy, Mamie
Thermal energy storage uses molten salt as a heat transfer fluid implies a high corrosion risk. In this work, ASTM A36 and AISI 304L steel, exposed to solar salt at 390 degrees C for 21 days, were studied by electrochemical impedance spectroscopy. The results were validated by mass gain and the characterization of corrosion products. Carbon steel revealed a porous behavior related to the formation of corrosion products based on iron oxides, as described the De Levies theory, whereas stainless steel showed the formation of a passive multilayer of iron and chromium oxides, which was adjusted to the Power-law model.
Modeling and Hourly Time-Scale Characterization of the Main Energy Parameters of Parabolic-Trough Solar Thermal Power Plants Using a Simplified Quasi-Dynamic Model
(2021) Arias, Ignacio; Zarza, Eduardo; Valenzuela, Loreto; Perez-Garcia, Manuel; Romero Ramos, Jose Alfonso; Escobar, Rodrigo
A simplified mathematical model of parabolic-trough solar thermal power plants, which allow one to carry out an energetic characterization of the main thermal parameters that influence the solar field performance, was evaluated through a comparison of simulation results. Two geographical locations were selected to evaluate the mathematical model proposed in this work-one in each hemisphere-and design considerations according with the practical/operational experience were taken. Furthermore, independent simulations were performed using the System Advisor Model (SAM) software, their results were compared with those obtained by the simplified model. According with the above, the mathematical model allows one to carry out simulations with a high degree of flexibility and adaptability, in which the equations that allow the plant to be energetically characterized are composed of a series of logical conditions that help identify boundary conditions between dawn and sunset, direct normal irradiance transients, and when the thermal energy storage system must compensate the solar field energy deficits to maintain the full load operation of the plant. Due to the above, the developed model allows one to obtain satisfactory simulation results; referring to the net electric power production, this model provides results in both hemispheres with a relative percentage error in the range of [0.28-8.38%] compared with the results obtained with the SAM, with mean square values of 4.57% and 4.21% for sites 1 and 2, respectively.
Net energy analysis for concentrated solar power plants in northern Chile
(PERGAMON-ELSEVIER SCIENCE LTD, 2012) Larrain, Teresita; Escobar, Rodrigo
Chilean energy policy goals attempts to promote efficiency and sustainability in the energy system. These objectives have been considered in recent modifications to the electricity generation laws by establishing that generation companies must reach a quota of up to a 10% from renewable energy sources by 2024. Concentrated solar power (CSP) is an interesting alternative to help achieve those objectives, as it is estimated that northern Chile has high radiation levels, coupled with the high values of the local clearness index and flat land availability. However, from the sustainability point of view it seems necessary to assess if a CSP plant is effectively an energy source. Here we propose a hybrid solar power plant lifecycle model which through a net energy analysis obtains and analyzes the plant energy sustainability attributes such as net energy, energy return over investment and energy payback time. The stages of construction, operation, maintenance and decommissioning are considered in the lifecycle analysis. The model is then applied in order to determine good locations where to install a CSP plant in the Chilean Atacama Desert. Monthly means of solar radiation are used in order to estimate the solar fraction for a 100MW direct steam generation parabolic trough collector plant. The results indicate that solar power plants are effectively a net energy source for the analyzed locations, and that higher energy costs are related to the fossil fuel backup lifecycle. A relation is established between yearly radiation, energy return over investment and energy payback time. It is estimated that the net energy analysis is a useful tool for determining under which conditions a power plant becomes a net energy source and therefore a more convenient option from the sustainability point of view, and thus can be utilized in order to define best geographical locations and operation conditions for different renewable energy sources. The sustainability attributes are greatly enhanced when considering a solar-only operation mode, which highlights the advantages of using that configuration, and presents a case for the use of thermal energy storage systems rather than fossil fuel hybridization if a constant or dispatchable energy profile is required. (C) 2011 Elsevier Ltd. All rights reserved.
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.
Performance model to assist solar thermal power plant siting in northern Chile based on backup fuel consumption
(PERGAMON-ELSEVIER SCIENCE LTD, 2010) Larrain, Teresita; Escobar, Rodrigo; Vergara, Julio
In response to environmental awareness, Chile introduced sustainability goals in its electricity law. Power producers must deliver 5% from renewable sources by 2010 and 10% by 2024. The Chilean desert has a large available surface with one of the highest radiation levels and clearest skies in the World. These factors imply that solar power is an option for this task. However, a commercial plant requires a fossil fuel system to backup the sunlight intermittency. The authors developed a thermodynamical model to estimate the backup fraction needed in a 100 MW hybrid -solar-fossil- parabolic trough power plant. This paper presents the model aiming to predicting the performance and exploring its usefulness in assisting site selection among four locations. Since solar radiation data are only available in a monthly average, we introduced two approaches to feed the model. One data set provided an average month with identical days throughout and the other one considered an artificial month of different daylight profiles on an hourly basis for the same monthly average. We recommend a best plant location based on minimum fossil fuel backup, contributing to optimal siting from the energy perspective. Utilities will refine their policy goals more closely when a precise solar energy data set becomes available. (C) 2010 Elsevier Ltd. All rights reserved.
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.
Techno-economic evaluation of hybrid solar thermal and photovoltaic cooling systems in the industrial sector implementing a dynamic load estimation method
(2025) Villarruel Jaramillo, Andrés Fabricio; Rosales Pérez, Josue Fihnlay; Pérez García, Manuel; Cardemil Iglesias, José Miguel; Escobar, Rodrigo
Hybrid solar cooling systems (HYBS) that combine air-to-water and absorption chillers driven by photovoltaic and solar thermal collector fields could improve the techno-economic performance of renewable cooling technologies in industrial applications. However, the limited access to dynamic cooling load data is a notable barrier to evaluating these systems. This research evaluates and compares the techno-economic performance of HYBS with conventional solar and fossil-powered alternatives. For this purpose, a dynamic cooling load profile method for the winemaking industry based on the conduction time series and the heat balance methods was developed, which only requires meteorological data and the annual volume of wine production. The HYBS were evaluated considering Chilean wine regions (high, medium and low solar radiation). The results showed that the HYBS could achieve the highest solar fraction values in all evaluated scenarios. Moreover, HYBS reaches a reduction of 7% of the levelized cost of heating and cooling in medium and low solar radiation sceneries, and the economic performance is highly influenced by the local cost of fossil energy. This research contributes to identifying the potential of HYBS in the industry and presents a useful method to generate dynamic cooling loads from commonly available data.
The impact of concentrated solar power in electric power systems : A Chilean case study
(2019) Mena, R.; Escobar, Rodrigo; Lorca Gálvez, Álvaro Hugo; Negrete Pincetic, Matías Alejandro; Olivares Quero, Daniel
The state of solar energy resource assessment in Chile
(PERGAMON-ELSEVIER SCIENCE LTD, 2010) Ortega, Alberto; Escobar, Rodrigo; Colle, Sergio; de Abreu, Samuel Luna
The Chilean government has determined that a renewable energy quota of up to 10% of the electrical energy generated must be met by 2024. This plan has already sparked interest in wind, geothermal, hydro and biomass power plants in order to introduce renewable energy systems to the country. Solar energy is being considered only for demonstration, small-scale CSP plants and for domestic water heating applications. This apparent lack of interest in solar energy is partly due to the absence of a valid solar energy database, adequate for energy system simulation and planning activities. One of the available solar radiation databases is 20-40 years old, with measurements taken by pyranographs and Campbell-Stokes devices. A second database from the Chilean Meteorological Service is composed by pyranometer readings, sparsely distributed along the country and available from 1988, with a number of these stations operating intermittently. The Chilean government through its National Energy Commission (CNE) has contracted the formulation of a simulation model and also the deployment of network of measurement stations in northern Chile. Recent efforts by the authors have resulted in a preliminary assessment by satellite image processing. Here, we compare the existing databases of solar radiation in Chile. Monthly mean solar energy maps are created from ground measurements and satellite estimations and compared. It is found that significant deviation exists between sources, and that all ground-station measurements display unknown uncertainty levels, thus highlighting the need for a proper, country-wide long-term resource assessment initiative. However, the solar energy levels throughout the country can be considered as high, and it is thought that they are adequate for energy planning activities although not yet for proper power plant design and dimensioning. (C) 2010 Elsevier Ltd. All rights reserved.
Thermal and lighting behavior of office buildings in Santiago of Chile
(ELSEVIER SCIENCE SA, 2012) Pino, Alan; Bustamante, Waldo; Escobar, Rodrigo; Pino, Felipe Encinas
Overheating, high cooling energy demand and glare are recurrent problems in office buildings in Santiago. It is necessary to know the influence of different architectural strategies in energy demands to meet thermal comfort of the users and energy efficiency. Based on dynamic simulations, cooling and heating demand are estimated for an office building located in Santiago. It is shown that the size of envelope's glazed areas highly influences the energy demand. A totally glazed facade building might reach up to 155 kWh/m(2) year for total cooling and heating demands. On the other hand, in a building with a window-to-wall ratio (WWR) of 20%, external solar protection and selective glazing, demand might be as low as 25 kWh/m(2) year. If night ventilation is applied during cooling periods an additional reduction of 37% can be achieved. A WWR of 20% is enough to keep a useful daylight around 80% of the time throughout the year. Main conclusions are: (i) for the climate conditions of Santiago, completely glazed facades are not recommended, even with selective glazing; (ii) night ventilation shows to be highly effective to reduce cooling demand; and (iii) lower WWRs with solar protection can achieve a better daylight performance than larger WWRs due to prevention of glare. (C) 2011 Elsevier B.V. All rights reserved.
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.

Browsing by Author "Escobar, Rodrigo"

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