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Fluidos y Térmicas – FLUTER

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Effect of concentration areas in sensitive analysis of a hybrid solar Brayton cycle

Moreno Gamboa, Faustino | 2021-06-11

A simple hybrid solar thermal Brayton cycle plant thermodynamic model is evaluated in northern Colombia, where the maximum solar radiation values in the country are found. The model considers the different irreversibilities of the cycle and is coupled to a model for estimating direct solar radiation as a complementary energy source for the plant. The stability in the operation of the cycle is determined by a combustion chamber that complements the energy supply. As a result of the analysis, this work presents the sensitivity analysis of different operating parameters of the plant as a function of the areas of the concentration ratio of the solar system when the contribution of this system is maximum. It is observed that fuel consumption is reduced by 34.7% when increasing the concentration ratio between 200 and 700.

Alternatives to Improve Performance and Operation of a Hybrid Solar Thermal Power Plant Using Hybrid Closed Brayton Cycle

Moreno Gamboa, Faustino | 2022-08-02

Hybrid solar thermal power plants using the Brayton cycle are currently of great interest as they have proven to be technically feasible. This study evaluates mechanisms to reduce fuel consumption and increase the power generated, improving plant efficiency. An energy and exergy model for the hybrid solar plant is developed using an estimation model for the solar resource to determine the plant operation under specific environmental conditions. The effect of using different working fluids in the Brayton cycle, such as air, and helium in transcritical conditions and carbon dioxide in subcritical and supercritical conditions, is evaluated. Additionally, the plant’s exergy destruction and exergy efficiency are evaluated. In those, it can be highlighted that the helium cycle in the same operating conditions compared to other working fluids can increase the power by 160%, increasing fuel consumption by more than 390%.

Analysis of a three-dimensional numerical modeling approach for predicting scour processes in longitudinal walls of granular bedding rivers

calixto, nelson javier | 2023-07-27

In rivers, longitudinal walls are protective structures that are directly supported on the riverbank are frequently used as hydraulic prevent the current from eroding the bank and causing scouring. However, these structures have the potential to block flow and produce erosive processes that progressively worsen scour in their area, leading to faulting and other problems. The current study used Flow-3D software to understand the scour process at the base of longitudinal walls in rivers with a well-graded granular bed. Experimental data from a physical model replicating a river with a longitudinal wall and a well-graded granular bed were used to validate the model. The investigation examined the average flow velocity and its effects on scour behavior along the longitudinal wall using the Flow-3D program. The findings showed that the Flow-3D model could improve the evaluation of debugging processes, because it provided a useful answer that closely matched the experimental data derived from the physical model. Validation with a 0.07 m mesh demonstrated that the Flow-3D model could faithfully simulate the scour process along the longitudinal wall. Overall, the findings of this study suggest that the Flow-3D software can be a useful tool for predicting the scouring process in rivers with well-graded granular beds and longitudinal walls. This is particularly important for engineers and researchers who are interested in designing and optimizing hydraulic structures to mitigate the effects of scouring, because it provided a useful answer that closely matched the experimental data derived from the physical model

Energy and exergetic performance analysis of a hybrid solar multi-stage Brayton cycle with different working fluids

Moreno Gamboa, Faustino | 2023-08-10

An energy and exergy model for a hybrid multi-stage Brayton cycle solar thermal plant is presented, incorporating an arbitrary number of compression stages with intermediate cooling and expansion with reheating. In hybrid operation, the cycle receives thermal energy from a solar concentration system of a heliostat field and a central tower complemented by reheaters and an external main combustion chamber of natural gas. The proposed model considers the irreversibility of the plant’s components, and direct solar radiation is estimated with the Daily Integration Approach model. The model is validated and implemented with the Solugas experimental plant parameters and is applied in Barranquilla, Colombia. Additionally, this work presents a comparative analysis of different plant configurations using air, carbon dioxide and helium as working fluids. Comparing the power, the energetic and exergetic efficiencies, and the destruction of exergy on an average day of the year, the maximum points of these variables are also found as a function of the pressure ratio. Observing that the twocompression-one-expansion CO2 cycle presents maximum fuel conversion rates and the slightest destruction of total exergy.

Analysis Of The Overturning Of Heavy Vehicles In The “The Adioses” Curve Of The Highway Pamplona-Cúcuta

Moreno Contreras, Gonzalo Guillermo | 2021-09

Over time, it has been observed that accidents due to vehicle overturning in the “The Adioses” curve of the Pamplona - Cúcuta road are a fairly frequent problem due to several factors such as: high speeds, absence of traffic signs, driver maneuvers, among others. This is why this section of the road has been classified as a critical accident point. The vehicles that are most affected are heavy vehicles (truck tractors), which due to their large size have a high gravity center, which hinders their stability compared to other vehicles. Another important aspect that it is taken into account is the characteristics of the road that can modify the load distribution in the vehicle. All these aspects are evaluated through a case study which allows calculating the stability factor for a particular heavy vehicle and calculating the safe traffic speed for this vehicle in the specified sector.

Thermodynamics performance optimization of a hybrid solar gas turbine power plant in Colombia

Moreno Gamboa, Faustino | 2022-02-10

A thermodynamic model is presented for evaluation of a solar hybrid gas-turbine power plant. The model uses variable ambient temperature and estimates direct solar radiation at different day times. The plant is evaluated in Barranquilla, Colombia, with a solar concentration system and a combustion chamber that burns natural gas. The hybrid system enables to maintain almost constant the power output throughout day. The model allows optimizing the different plant parameters and evaluating maximum performance point. This work presents pressure ratio ranges where the maximum values of overall efficiency, power output, thermal engine efficiency and fuel conversion rate are found. The study is based on the environmental conditions of Barranquilla, Colombia. The results obtained shows that optimum pressure ratio range for power output and overall efficiency is between 6.4 and 8.3, when direct solar radiation its maximum at noon. This thermodynamic analysis is necessary to design new generations of solar thermal power plants.

Effect of a regenerator on hybrid solar gas turbine performance in Barranquilla, Colombia

Moreno Gamboa, Faustino | 2021

A thermodynamic analysis of a hybrid gas turbine solar plant, represented in three basic subsystems related to the power cycle, the combustion chamber subsystem, and the solar concentrator subsystem, allows evaluating the performance of a hybrid cycle from a reduced number of parameters, which include energy losses in each of its components. The solar radiation values are estimated with an evaluated and validated theoretical model, the combustion chamber uses natural gas as fuel and the numerical values of the system are taken from the Solugas experimental plant in Spain. This work presents an integrated model that allows to estimate the operation of a hybrid solar Brayton power plant in any place and day of the year. The evaluation of the plant in Barranquilla, Colombia is shown from the influence of the regenerator has on the plant performance and solar concentrating system. The results show that the regenerator can increase the overall efficiency of the plant by 29% and allows reaching a maximum temperature of the central receiver of the concentrator of 1044 K at noon, when solar radiation is maximum.

Daily performance of a solar hybrid regenerative gas turbine in Colombia

Moreno Gamboa, Faustino | 2021-06-11

This work presents the evolution of the operation of a regenerative hybrid solar gas turbine in an average day of the year. The system is evaluated by means of a thermodynamic model that includes a solar concentrated heliostat field solar concentrator with central receiver, a combustion chamber, and the thermal engine. The model is applied in Barranquilla, Colombia using local temperature and the solar radiation estimated with a theoretical model. Power output, the global efficiency and thermal engine efficiency are estimated. Additionally, to estimate the temperatures in different states of the cycle with and without regenerator. Finally, the impact of the regenerator is evaluated, which can increase the temperature of the solar receiver by up to 13.6%, and the inlet temperature to the combustion chamber increases by 17.3% at noon, when solar radiation is maximum.

Analysis of the physicochemical process in the production of biogas from equine manure

Sanchez-Beltrán, J M | 2021

. The present research aims to evaluate the physicochemical variables involved in the anaerobic digestion process to produce methane from manure on an agricultural farm; the farm has 2 equines that generate 12 Kg of manure per day. A manure sample was collected, and the following physicochemical parameters were determined: total solids, volatile solids, chemical oxygen demand, and pH. A tubular household biodigester was then implemented, consisting mainly of a polyethylene geomembrane that stores the organic matter and in which anaerobic digestion takes place. The performance of the biodigester was determined by the removal of organic matter quantified by volatile solids and chemical oxygen demand in the biodigester influent and digestate, of which removal of 82% of volatile solids and 74% of chemical oxygen demand was achieved. The average biogas production was 0.5 m3 /day, and its lower heating value was 26,000 kJ/m3 . The pH level of the biodigester was within the range of 6-7, in order to keep the methanogenic bacteria active, in charge of carrying out physicochemical process that guarantees anaerobic digestion and thus, the production of biogas.

Solar energy: a source for water disinfection in Colombia

Barajas Forero, Carmen Leonor | 2016-05-20

Colombia, due to its geographical position, receives a high solar radiation throughout the year. This implies that the country has great potential for solar energy production, but can also use this resource to enhance the living conditions of its inhabitants by using solar radiation to improve the quality of drinking water. Mainly in rural areas, the country has serious problems with drinking water for its inhabitants. This generates high morbidity and mortality, especially in children under five. The main purpose of this preliminary work was to investigate if weather conditions in northeastern Colombia permit to use the sun's energy to disinfect water from water sources which are normally heavily contaminated. The results are encouraging and may lead to establish programs for appropriate use of this technology in areas where the construction of treatment plants very difficult.

Determinación de la emisividad de llama y el calor de radiación por combustión en el hogar de una caldera

Rubio Ramirez, Cristian Ricardo | 2016-06-12

El calor de radiación depende de la emisividad del cuerpo y de la temperatura a la que éste se encuentra. En el caso de los productos que se generan por combustibles líquidos, se considera la emisividad luminosa, causada por la flama, y la emisividad no luminosa, producida por los gases. Se establece una comparación entre el cálculo de la emisividad no luminosa descrita por Michael Modest en su libro Radiative heat transfer y los cálculos propuestos por Prabir Basu, Cen Kefa y Louis Jestin, en su libro Boilers and burnes, design and theory. Además, se contrasta el total de la energía de radiación calculada por ambos métodos.

Modelo matemático de la transferencia de calor en el hogar de una caldera pirotubular

Rubio Ramirez, Cristian Ricardo | 2016-12-30

El tubo principal de una caldera denominado hogar, cumple la función de aprovechar la energía liberada por el combustible para efectos de evaporar el agua. Se varía el exceso de aire para observar los cambios en la cantidad de transferencia de calor. Para el estudio se utiliza el software EES.

Prototipo de sistema remoto para el análisis del recurso eólico en zonas rurales de Colombia

Vásquez Vega, Alejandro | 2017-06

Se diseña y construye el prototipo de un sistema remoto para el sensado, análisis y caracterización del recurso eólico en las zonas rurales de Colombia. El montaje del prototipo se realiza en una estructura opcional de globo sonda cautivo, y, mediante una herramienta elaborada bajo un entorno de desarrollo integrado, se determina la viabilidad y las características de un futuro emplazamiento eólico in situ, a partir de las mediciones de dirección del viento, velocidad a dos diferentes alturas y condiciones meteorológicas influyentes como humedad, temperatura y presión barométrica.

Modelo de transferencia de calor por ebullición de una caldera horizontal de 10BHP

Rubio Ramirez, Cristian Ricardo | 2018-09-28

Se deduce y analiza el modelo matemático de la ebullición en las calderas de tipo pirotubular teniendo en cuenta los primeros estudios de nucleación, y los postulados de carácter empírico que desarrollaron las ecuaciones de comportamiento de evaporación. Se observa la cantidad de energía que es capaz de recibir el agua, detallando los mecanismos por los cuales lo hace. Con estos valores se calcula el coeficiente de transferencia de calor por convección generado en la ebullición, dependiendo de la presión de operación a la cual trabaja la caldera. Además, se calcula el tamaño de las burbujas que se crean alrededor de las superficies de calentamiento, según la orientación horizontal de los tubos y el hogar.

Modelado termodinámico de una planta solar térmica hibrida de ciclo Brayton en Colombia

Moreno Gamboa, Faustino | 2018-12-18

Introducción: Actualmente en Colombia, existe gran interés por la aplicación de energías renovables y la diversificación de la matriz energética. Por lo tanto, en el presente trabajo se muestran los resultados de la simulación de una planta solar térmica hibrida de ciclo Brayton cerrado en Colombia, que recibe calor de un sistema de concentración de torre central y heliostatos. El recurso solar se estima por un modelo horario, adicionalmente cuenta con una cámara de combustión que utiliza gas natural como combustible, la cual garantiza la estabilidad del calor suministrado a la planta. La ubicación de la planta se selecciona en función de la radiación global y difusa media diaria mensual, y adicionalmente, se realiza una simulación de los principales parámetros de operación, optimizando la potencia y el rendimiento global en función de la relación de presión. Por último, se realiza un análisis exergético de la planta, especialmente de los componentes afectados por la variación de la radiación en el día. Objetivo: Evaluar una planta solar térmica de concentración de ciclo Brayton cerrado, desde el punto de vista energético y exegético bajo las condiciones ambientales de Colombia. Metodología: Integrar en lenguaje modélica, por medio de un compilador Dymola un modelo de recurso solar, un modelo energético y un modelo exergético aplicado a las condiciones ambientales de Colombia. Resultados: Se presenta el análisis correspondiente a la evolución de los principales parámetros de operación de la planta a lo largo del día, la variación del rendimiento y la potencia en función de la relación de presiones. Conclusiones: Es viable técnicamente la operación de una planta solar térmica de concentración de ciclo Brayton en algunos lugares de Colombia, dado el recurso solar disponible y el ahorro de combustible que genera a pesar del detrimento del rendimiento energético y exergético.

Estudio de diferentes modelos de turbulencia para obtener las curvas características de un perfil naca 2415 mediante la simulación tridimensional de flujos de fluidos

Mendoza, Luis Daniel | 2019-01-22

Se realizó un análisis computacional, mediante la técnica del CFD, del perfil NACA 2415, con los modelos de turbulencia Realizable K-ε y el modelo de turbulencia K-ω SST para obtener sus curvas aerodinámicas. El software utilizado fue el ANSYS FLUENT V14. La simulación se realizó con mallas no estructuradas y bidimensionales, en un dominio computacional cuyas dimensiones corresponden al túnel de viento AF6109 de la Universidad Nacional Experimental del Táchira, Venezuela. Las curvas aerodinámicas se realizaron para diferentes ángulos de ataque, los cuales consistieron en 0°, 4°, 8°, 12° y 16° respectivamente. Las condiciones de borde usadas están basadas en el túnel de viento AF6109. La simulación computacional se validó con las curvas aerodinámicas obtenidas mediante el diseño experimental realizado en el túnel de viento. Se concluye que el modelo de turbulencia K-ω SST predice mejor los gradientes adversos de presión.

Influencia de productos de la hidrólisis en el desempeño de un vehículo que opera con gasolina y gas natural en la altura

Moreno Gamboa, Faustino | 2019-04-24

Introducción: En la actualidad existe un gran interés en la reducción en el uso de combustibles fósiles por la variación de los precios y los fuertes controles normativos, por lo cual se buscan métodos para disminuir el consumo de combustible en los motores de combustión interna, tales como el suministro de productos de la hidrólisis del agua en la admisión del motor. Objetivo: El objetivo del este trabajo es presentar los resultados de una metodología experimental aplicada para estimar el desempeño mecánico y ambiental de un vehículo alimentado con gasolina y gas natural, específicamente cuando al motor se le suministran productos resultantes de la hidrólisis del agua. Metodología: Para el suministro de dichos productos al vehículo se le instalo un dispositivo hidrólisis externo, y el vehículo fue instrumentado con una quinta rueda, sensores de temperatura y velocidad de revoluciones del motor, para realizar pruebas de aceleración en una carretera plana y una carretera con pendiente longitudinal. Adicionalmente, se realizaron pruebas de torque y potencia con dinamómetro de chasis y pruebas de emisiones contaminantes y de consumo de combustible. Las pruebas fueron realizadas en las afueras de la ciudad de Bogotá DC - Colombia, ubicada a 2650 m sobre el nivel del mar. Resultados: Los resultados muestran que los productos de la hidrólisis no mejoran el desempeño mecánico del vehículo, ya que aumentan el tiempo para llegada a las velocidades definidas en las pruebas de aceleración hasta en un 18% en el motor con gasolina y 7% en el motor con gas natural, mientras que el torque y la potencia del motor se incrementa alrededor del 1%. Por otro lado, los resultados de las pruebas de emisiones contaminantes indican que el consumo de combustible se reduce aproximadamente en un 7%. Conclusiones: Los resultados indican que el desempeño del vehículo no mejora, aunque el consumo de combustible disminuye, el desempeño ambiental no disminuye.

Modeling and simulation of an electrolyser for the production of HHO in Matlab- Simulink

Rincón Castrillo, Erick Daniel | 2019-05-01

The electrolyzers work through an electrochemical process, their derivatives (H2, O2, and HHO) are used as enriching fuels due to the electrolysis of water, being cleaner than gasoline and diesel. This article presents the dynamic model of an alkaline electrolyzer that uses an electrolyte (KOH o NaHCO3) dissolved in distilled water to accelerate the production of oxyhydrogen (HHO). The model shows the phase change that occurs inside the electrolytic cell. The EES® software was used to determine the values of enthalpy, entropy, and free energy that vary during the electrochemical reaction; the equations were simulated in Matlab-Simulink® to observe their dynamic behavior. The Simulations presented varying every 5 g the electrolyte until reaching 20 g. The flow rate of HHO with potassium hydroxide (20 g) is higher than 0.02 L / s, and with sodium bicarbonate (20 g) it is above 0.0006 L / s, confirming what the literature of alkaline cells state, that the most efficient electrolyte for its energy conversion is KOH

Metodología para el cálculo del desempeño térmico de turbuladores helicoidales en calderas de vapor: modelo matemático y simulación

Rubio Ramirez, Cristian Ricardo | 2019-09-23

El desempeño térmico que hoy en dia ofrecen las maquinas generadoras de vapor es medido principalmente por la cantidad de calor que es aprovechado. Para incrementar la transferencia de calor dentro los recipientes de presión se usan turbuladores que distribuyen uniformemente el contenido de gases de combustión al paso del haz de tubos. En este artículo se analizó el desempeño de los turbuladores helicoidales al interior de una sección del haz de tubos, presente en el segundo paso de calentamiento de una caldera pirotubular. Se deduce el modelo matemático de la transferencia de calor de los gases de combustión de acuerdo al régimen de fluidez. Para la caracterización del modelo se obtienen los contornos de imagen a partir de fotogrametría digital, apoyados en el software CAD para el procesamiento del sólido en 3D. Se realiza la simulación de los flujos de gases que atraviesan estos dispositivos, calculando la temperatura de los gases, componentes de velocidad, transferencia de calor y caídas de presión, comparando los resultados con un entorno sin turbulador aumentando la transferencia de energía en un 31,23%. Así mismo se establece un patrón de la trayectoria que obtienen los gases en presencia de los turbuladores.

Performance evaluation of external fired hybrid solar gas-turbine power plant in Colombia using energy and exergy methods

Moreno Gamboa, Faustino | 2020-12-01

Hydro and thermal generation power systems dominate the Colombian electricity sector. In 2017, Colombia installed electrical generation capacity was 16.8 GW. Renewable energy sources represent at least 85% of the total generation, being hydro the principal source. Several alternatives had been evaluated through the years to improve the Colombian energy matrix and capacity, including solar photovoltaic and wind plants; despite that, no consensus about the appropriate solution in terms of the available resource, energy demand, and energy mix has been attained. Thermosolar power plants arise as an alternative to produce energy in sites where nearly constant solar irradiance throughout the year is available, which is the case for most Colombian cities. This work concerned the evaluation of a single-stage hybrid Central Solar Power (CSP) plant at a location on the Caribbean Colombian coast. The study is focused on establishing the effect of local environmental conditions (ambient temperature and solar resource availability), as well as some operational cycle parameters (heat exchanger effectiveness and the system pressure ratio) on the CSP plant performance. Additionally, site emplacement conditions, i.e., proximity to the power grid, presence of conventional thermal power plants, proximity to principal cities, and availability of natural gas), are also considered to attain the factors that might constrain the plant optimal operating conditions. The CSP plant and the Direct Normal Irradiance (DNI) model results obtained fitted in good agreement the experimental data from the literature used for validation. Results have shown a global plant efficiency of 35% without solar resource which is reduced to 30% when solar contribution attains its maximum value at midday. Additionally, fuel-saving per day varies between 9.21% and 6.3% during the months of maximum and minimum global radiation, respectively. Finally, that the combustion chamber, its associated heat exchanger and the one that is in direct exchange with the surroundings, are the components with the most exergy destruction, as expected. From the above, it is sensible to explore alternatives regarding different working fluids that could be used in lower temperature cycles and other applications for heat recovery.