institución: Biotecnología & Bioingeniería Core S.A, diseñaron un dispositivo compacto y portátil... more institución: Biotecnología & Bioingeniería Core S.A, diseñaron un dispositivo compacto y portátil para terapia respiratoria CPAP en niños prematuros, que resulta innovador frente a los que existen actualmente en el mercado. Desar rollo de dispo sitivo comp acto y portá til para terap ia CPAP de burbu ja en neon atos Invest igador es princi pales
A computational simulation of the thermo hydraulic performance of a trapezoidal Off Set Strip Fin... more A computational simulation of the thermo hydraulic performance of a trapezoidal Off Set Strip Fin (OSF) is performed. The simulations are carried for Reynolds number ranging from 300 to 9000 considering three-dimensional conditions (3D). Calculations were developed assuming a constant flow. Colburn factor j, and the friction factor f, were calculated. Uniform temperature condition is assumed at the solid surface and at the inlet. The results have been compared with studies made by Kays and London, (1984), Manglik and Bergles (1990), and Muzychka and Yovanovich, (2001). According to the obtained results, it can be concluded that Computational Fluid Dynamics (CFD) is able to explore the behavior and performance of this kind of fin, showing that the hydraulic performance is well represented by correlations widely used in literature, while thermal performance seems to be under predicted.
The intrinsic heterogeneous reactivity of biochar in CO2 and steam gasification plays an importan... more The intrinsic heterogeneous reactivity of biochar in CO2 and steam gasification plays an important role in thermochemical reactor design, adjusting operating conditions, and predicting the quality of biomass gasification products, especially when the combined valorization of syngas and biochar with important textural properties is required. In the present work, the intrinsic heterogeneous kinetics of CO2 and steam gasification of corn biochar is estimated by fitting a multimodal pore size distribution (PSD) with random capillary model evolution with respect to the experimental results by thermogravimetric analysis (TGA). As novelty the independence of the initial biochar textural properties was considered, using two samples with different initial pore size distributions (PSDs): A1 sample with an initial surface area of 54.09 m2/g and A2 sample with 22.14 m2/g. The experimental intraparticle gradient effect is considered by using samples with a particle size of 149 µm conventionally ...
Resumen: La teoría de adición de masa es aplicada a la predicción de las fuerzas vertical y horiz... more Resumen: La teoría de adición de masa es aplicada a la predicción de las fuerzas vertical y horizontal y momento restaurador que actúan durante la entrada de secciones tipo cuña con pequeña asimetría antes de la separación del flujo del codillo. Los resultados obtenidos de fuerza horizontal, vertical y momento de rolido se comparan con valores derivados por simulación con CFD y los resultados obtenido por Xu G. (2008). El cálculo del coeficiente de adición de masa se realizó utilizando el modelo de Toyama (1993). Palabra claves: Impacto en 2D, teoría de adición de masa, entrada asimétrica. Abstract: Adding mass theory is applied for the prediction of the vertical and horizontal forces and restoring moment acting during wedge type input sections with small asymmetry before flow separation knuckle. The results for horizontal, vertical and roll moment are compared with values derived by CFD simulations and the results obtained by Xu G. (2008). The coefficient calculation of differe...
Volume 8: Heat Transfer and Thermal Engineering, 2017
Paddy drying is one of the main operations on the rice milling industry and it has a wide impact ... more Paddy drying is one of the main operations on the rice milling industry and it has a wide impact in terms of kernel quality, infestation reduction and costs of operation. That is why process control is one of the main fields to ensure a successful operation. This paper presents the development of an industrial scale drying rate prediction model. The model includes on his structure mass balance equations, drying rate and bulk density equation and an experimental expression that estimates the rate of change in moisture as a function of the dry basis kernel water fraction, Sherwood number, mass transfer Biot number and a proposed non-dimensional temperature -Nt-. The importance of including -Nt- parameter is based on the thermal gradients between the drying air, internal kernel water and the installation environmental conditions. These factors create a distinctive characteristic from other drying rate prediction models because they associate the process with environmental conditions of...
For every nine tons of produced biodiesel, there is another ton of glycerol as a byproduct. There... more For every nine tons of produced biodiesel, there is another ton of glycerol as a byproduct. Therefore, glycerol prices dropped significantly worldwide in recent years; the more significant biodiesel production is, the more glycerol exists as a byproduct. glycerol prices also impact the biodiesel manufacturing business, as it could be sold according to its refinement grade. The primary objective of this work was to evaluate the economic potential of the production of 1,2-propanediol derived from the biodiesel produced in Colombia. A plant to produce 1,2-propanediol via catalytic hydrogenation of glycerol in a trickle-bed reactor was designed. The plant comprised a reaction scheme where non-converted excess hydrogen was recycled, and the heat generated in the reactor was recovered. The reactor effluent was sent to a separation train where 98% m/m purity 1,2-propanediol was attained. Capital and operational costs were estimated from the process simulation. The net present value (NPV) a...
Propylene glycol, also known as 1,2 propanediol, is one of the most important chemicals in the in... more Propylene glycol, also known as 1,2 propanediol, is one of the most important chemicals in the industry. It is a water-soluble liquid, considered by the U.S. Food and Drug Administration as safe to manufacture consumer products, including foodstuffs, medicines, and cosmetics. This chemical has essential properties, such as solvent, moisturizer, or antifreeze, in addition to a low level of toxicity. This paper aims to present the selection, simulation, and dimensioning of a trickle bed reactor at a laboratory scale. The sizing was validated with other authors. Two predictive models have been considered for reactor modeling, intrinsic kinetics and coupled intrinsic kinetics, along with mass transfer equations and the wetting of the catalyst particles. The model was implemented using Aspen Custom Modeler® (20 Crosby Dr. Bedford, MA 01730, EE. UU.) to study the reactor behavior in terms of conversion. The results show the profiles of different variables throughout the reactor and presen...
Advance Journal of Food Science and Technology, 2018
An experimental procedure was carried out to maximize Chaetoceros gracilis growth. Chaetoceros gr... more An experimental procedure was carried out to maximize Chaetoceros gracilis growth. Chaetoceros gracilis, marine microalgae, is considered for feeding fisheries with no GMO (Genetically Modified Organisms) to avoid human health hazards. Furthermore, following United Nations Resolution on water, the microalgae is grown in photobioreactors due to its low water usage. To maximize the microalgae growth, an experimental design was carried out to analyze the effects of Light Intensity, CO2 supply per day, Sparger type, Photoperiod and Inlet airflow, pH and water temperature were monitored but not controlled. It was found that Light intensity and CO2 supply per day have statistical significance. Out of three possible scenarios, 1700 lux and 80 gr/day of CO2, leads to a cell density at day three of 310×10 4 cel/mL which represents 20% more of the density attained in day two under bag (standard) growing conditions. It was also found that water Ph has also a strong effect over cell density.
Planing boat dynamics are a complex phenomenon and the maneuver forces acting on these kind of hu... more Planing boat dynamics are a complex phenomenon and the maneuver forces acting on these kind of hulls are difficult to predict. In the current work, a mathematical model of a two-dimensional impact with three degrees of freedom (3DOF) is developed. The model was used to study wedge sections with knuckles, the vertical, horizontal, and rotational motion are considered. Pressure distribution, forces, and motion during the impact, considering both free fall and forced motion, are evaluated. The commercial CFD (Computational flow dynamics) software Star-CCM+ V9.06 was used to validate the formulation. Simulations with one, two, and three degrees of freedom were carried out, and the results were compared with CFD simulations, experimental data, and numerical solutions by others authors. The results show a good agreement with the authors. The model is extended to three dimensions applying slender body theory, and the forces in the hull are computed. The formulation allows evaluating the se...
This work analyzes the use of palm kernel shells (PKS) produced by the Colombian palm oil mill in... more This work analyzes the use of palm kernel shells (PKS) produced by the Colombian palm oil mill industry, for purposes of fueling a commercial downdraft fixed bed gasifier (Ankur Scientific WGB- 20) designed to operate with wood chips. Operational parameters such as hopper shaking time, ash removal time, and airflow were varied in order to get the highest gasifier performance, computed as the ratio between producer gas chemical energy over biomass feeding energy. Experiments were carried out following a half fraction experimental design 24-1. Since these parameters affect the equivalence ratio (ER), behavior indicators were analyzed as a function of ER. It was found that the shaking time and airflow had a significant effect on higher-heating-value (HHV) and process efficiency, while the removal time is not significant. The highest performance for palm shell was reached at ER=0.35, where the resulting gas HHV and process efficiencies were 5.04 MJ/Nm3 and 58%, respectively.
In this article, data from a 3.5kW mini split air conditioning is presented. A screening 2 3 desi... more In this article, data from a 3.5kW mini split air conditioning is presented. A screening 2 3 design experiment was performed to evaluate the effects of indoor air temperature, absolute humidity and evaporator fan speed in the performance of the air conditioning. This dataset also includes noise factors as outdoor air temperature, fans energy consumption and response as indoor air exit conditions.
The Goswami cycle is a cycle that combines an ammonia–water vapor absorption cycle and a Rankine ... more The Goswami cycle is a cycle that combines an ammonia–water vapor absorption cycle and a Rankine cycle for cooling and mechanical power purposes by using thermal heat sources such as solar energy or geothermal steam. In this paper, a theoretical investigation was conducted to determine the performance outputs of the cycle, namely, net mechanical power, cooling, effective first law efficiency and exergy efficiency, for a boiler and an absorber temperature of 85 °C and 35 °C, respectively, and different boiler pressures and ammonia-water concentrations. In addition, an experimental investigation was carried out to verify the predicted trends of theoretical analysis and evaluate the performance of a modified scroll expander. The theoretical analysis showed that maximum effective first law and exergy efficiencies were 7.2% and 45%, respectively. The experimental tests showed that the scroll expander reached a 30–40% of efficiency when boiler temperature was 85 °C and rectifier temperatu...
A 2D computational fluid dynamics simulation was carried out using a multiphase flow model with a... more A 2D computational fluid dynamics simulation was carried out using a multiphase flow model with an Eulerian-Eulerian approach for a microalgae culture in an airlift column photobioreactor. Simulation was performed for a 0.0625 l/l culture •min inlet airflow. Air, water and microalgae velocity contours showed less gas phase present in the downcomer than in the riser, suggesting the necessity of vigorous mixing in the ascendant portion if homogeneous water and solid flow is to be achieved. Air velocity is smaller in the downcomer (shorter velocity vectors) than in the riser. Water velocity vectors point always in the expected direction, down in the downcomer and up in the riser. Microalgae paths, perhaps due to the small size of the microorganisms, follow the water velocity vectors. As there are fewer hydraulic restrictions to the liquid phase in the riser, a large amount of energy is dissipated by gas-liquid interactions. In the downcomer region, the gas phase is almost nonexistent, and bubble collisions are almost nonexistent as well. A quasi-stagnation zone was found at the lower section of the downcomer, showing that the design requires improvement. Finally, the turbulent kinetic energy is larger at the top and middle region of the riser; meanwhile, it is lower at the downcomer. Similar results were observed for the energy dissipation rate.
The 2D impact phenomenon in calm water, considering symmetric entry with vertical velocity is stu... more The 2D impact phenomenon in calm water, considering symmetric entry with vertical velocity is studied. The analysis was performed by using commercial STAR-CCM+ computational fuid dynamics software. Thee results obtained from the simulations are pressure distribution and force during impact. The study was carried out for typical planning of boat sections. The results are compared with models and data obtained from some authors and they present very good agreement.
This paper analyzes the feasibility of applying model predictive control strategies for mitigatio... more This paper analyzes the feasibility of applying model predictive control strategies for mitigation of the auto-ignition phenomenon, which affects the performance of spark-ignition internal combustion engines. The first part of this paper shows the implementation and experimental validation of a two-dimensional model, based on thermodynamic equations, to simulate operating conditions in engines fueled with natural gas. Over this validated model, several control strategies are studied in order to evaluate, through simulation analysis, which of these offer the best handling capacity of the auto-ignition phenomenon. In order to achieve this goal, multivariate control strategies are implemented for a simultaneous manipulation of the fuel/air ratio, the crank angle at ignition, and the inlet pressure. The controlled variable in this research is the temperature at the ignition point. This temperature is obtained through an estimation based on pressure in the combustion chamber at that poin...
This paper studied, through an experiment design, the significance of particle size, air speed an... more This paper studied, through an experiment design, the significance of particle size, air speed and reactor arrangement for palm shell micro-gasification process in order to optimize the heating value of the syngas obtained. The range of variables was 8 to 13 mm for particle size, 0.8–1.4m/s for air velocity, and updraft or downdraft for the reactor type. It was found that the particle size and air velocity factors were the most significant in the optimization of the output variable, syngas heating value. A heating value of 2.69MJ / Nm3 was obtained using a fixed bed downdraft reactor, with a particle size of 13 mm and 1.4 m/s for air speed; verification of the optimum point of operation under these conditions verified that these operating conditions favor the production of a gas with a high energy value.
institución: Biotecnología & Bioingeniería Core S.A, diseñaron un dispositivo compacto y portátil... more institución: Biotecnología & Bioingeniería Core S.A, diseñaron un dispositivo compacto y portátil para terapia respiratoria CPAP en niños prematuros, que resulta innovador frente a los que existen actualmente en el mercado. Desar rollo de dispo sitivo comp acto y portá til para terap ia CPAP de burbu ja en neon atos Invest igador es princi pales
Volume 4: Heat and Mass Transfer Under Extreme Conditions; Environmental Heat Transfer; Computational Heat Transfer; Visualization of Heat Transfer; Heat Transfer Education and Future Directions in Heat Transfer; Nuclear Energy, 2013
A computational simulation of the thermo hydraulic performance of a trapezoidal Off Set Strip Fin... more A computational simulation of the thermo hydraulic performance of a trapezoidal Off Set Strip Fin (OSF) is performed. The simulations are carried for Reynolds number ranging from 300 to 9000 considering three-dimensional conditions (3D). Calculations were developed assuming a constant flow. Colburn factor j, and the friction factor f, were calculated. Uniform temperature condition is assumed at the solid surface and at the inlet. The results have been compared with studies made by Kays and London, (1984), Manglik and Bergles (1990), and Muzychka and Yovanovich, (2001). According to the obtained results, it can be concluded that Computational Fluid Dynamics (CFD) is able to explore the behavior and performance of this kind of fin, showing that the hydraulic performance is well represented by correlations widely used in literature, while thermal performance seems to be under predicted.
The thermal performance of building materials used in Colombia is not currently characterized, wh... more The thermal performance of building materials used in Colombia is not currently characterized, which is essential to obtain the necessary information for an architectural design based on energy efficiency. The determination of materials thermal properties, as well as thermal and energy performance of building materials commonly used in Colombia are the main challenges for this research. The proposed methodology implies the experimental determination of the different materials thermal properties through the design and construction of an experimental device capable to accommodate different materials configurations. This will allow us to obtain relevant information to develop the government’s energy standards for quality building materials and quality policies for private companies. Among others are included: the Environmental Seal for Sustainable Building, which is currently being developed by the Colombian Council of Sustainable Building (CCCS); the Colombian standard for thermal systems applications in buildings (RITE) currently being developed by the Colombian Association of Air Conditioning and Refrigeration (ACAIRE); and policies for national sustainable buildings that were included in the National Development Plan 2010–2014 and 2015–2019.
institución: Biotecnología & Bioingeniería Core S.A, diseñaron un dispositivo compacto y portátil... more institución: Biotecnología & Bioingeniería Core S.A, diseñaron un dispositivo compacto y portátil para terapia respiratoria CPAP en niños prematuros, que resulta innovador frente a los que existen actualmente en el mercado. Desar rollo de dispo sitivo comp acto y portá til para terap ia CPAP de burbu ja en neon atos Invest igador es princi pales
A computational simulation of the thermo hydraulic performance of a trapezoidal Off Set Strip Fin... more A computational simulation of the thermo hydraulic performance of a trapezoidal Off Set Strip Fin (OSF) is performed. The simulations are carried for Reynolds number ranging from 300 to 9000 considering three-dimensional conditions (3D). Calculations were developed assuming a constant flow. Colburn factor j, and the friction factor f, were calculated. Uniform temperature condition is assumed at the solid surface and at the inlet. The results have been compared with studies made by Kays and London, (1984), Manglik and Bergles (1990), and Muzychka and Yovanovich, (2001). According to the obtained results, it can be concluded that Computational Fluid Dynamics (CFD) is able to explore the behavior and performance of this kind of fin, showing that the hydraulic performance is well represented by correlations widely used in literature, while thermal performance seems to be under predicted.
The intrinsic heterogeneous reactivity of biochar in CO2 and steam gasification plays an importan... more The intrinsic heterogeneous reactivity of biochar in CO2 and steam gasification plays an important role in thermochemical reactor design, adjusting operating conditions, and predicting the quality of biomass gasification products, especially when the combined valorization of syngas and biochar with important textural properties is required. In the present work, the intrinsic heterogeneous kinetics of CO2 and steam gasification of corn biochar is estimated by fitting a multimodal pore size distribution (PSD) with random capillary model evolution with respect to the experimental results by thermogravimetric analysis (TGA). As novelty the independence of the initial biochar textural properties was considered, using two samples with different initial pore size distributions (PSDs): A1 sample with an initial surface area of 54.09 m2/g and A2 sample with 22.14 m2/g. The experimental intraparticle gradient effect is considered by using samples with a particle size of 149 µm conventionally ...
Resumen: La teoría de adición de masa es aplicada a la predicción de las fuerzas vertical y horiz... more Resumen: La teoría de adición de masa es aplicada a la predicción de las fuerzas vertical y horizontal y momento restaurador que actúan durante la entrada de secciones tipo cuña con pequeña asimetría antes de la separación del flujo del codillo. Los resultados obtenidos de fuerza horizontal, vertical y momento de rolido se comparan con valores derivados por simulación con CFD y los resultados obtenido por Xu G. (2008). El cálculo del coeficiente de adición de masa se realizó utilizando el modelo de Toyama (1993). Palabra claves: Impacto en 2D, teoría de adición de masa, entrada asimétrica. Abstract: Adding mass theory is applied for the prediction of the vertical and horizontal forces and restoring moment acting during wedge type input sections with small asymmetry before flow separation knuckle. The results for horizontal, vertical and roll moment are compared with values derived by CFD simulations and the results obtained by Xu G. (2008). The coefficient calculation of differe...
Volume 8: Heat Transfer and Thermal Engineering, 2017
Paddy drying is one of the main operations on the rice milling industry and it has a wide impact ... more Paddy drying is one of the main operations on the rice milling industry and it has a wide impact in terms of kernel quality, infestation reduction and costs of operation. That is why process control is one of the main fields to ensure a successful operation. This paper presents the development of an industrial scale drying rate prediction model. The model includes on his structure mass balance equations, drying rate and bulk density equation and an experimental expression that estimates the rate of change in moisture as a function of the dry basis kernel water fraction, Sherwood number, mass transfer Biot number and a proposed non-dimensional temperature -Nt-. The importance of including -Nt- parameter is based on the thermal gradients between the drying air, internal kernel water and the installation environmental conditions. These factors create a distinctive characteristic from other drying rate prediction models because they associate the process with environmental conditions of...
For every nine tons of produced biodiesel, there is another ton of glycerol as a byproduct. There... more For every nine tons of produced biodiesel, there is another ton of glycerol as a byproduct. Therefore, glycerol prices dropped significantly worldwide in recent years; the more significant biodiesel production is, the more glycerol exists as a byproduct. glycerol prices also impact the biodiesel manufacturing business, as it could be sold according to its refinement grade. The primary objective of this work was to evaluate the economic potential of the production of 1,2-propanediol derived from the biodiesel produced in Colombia. A plant to produce 1,2-propanediol via catalytic hydrogenation of glycerol in a trickle-bed reactor was designed. The plant comprised a reaction scheme where non-converted excess hydrogen was recycled, and the heat generated in the reactor was recovered. The reactor effluent was sent to a separation train where 98% m/m purity 1,2-propanediol was attained. Capital and operational costs were estimated from the process simulation. The net present value (NPV) a...
Propylene glycol, also known as 1,2 propanediol, is one of the most important chemicals in the in... more Propylene glycol, also known as 1,2 propanediol, is one of the most important chemicals in the industry. It is a water-soluble liquid, considered by the U.S. Food and Drug Administration as safe to manufacture consumer products, including foodstuffs, medicines, and cosmetics. This chemical has essential properties, such as solvent, moisturizer, or antifreeze, in addition to a low level of toxicity. This paper aims to present the selection, simulation, and dimensioning of a trickle bed reactor at a laboratory scale. The sizing was validated with other authors. Two predictive models have been considered for reactor modeling, intrinsic kinetics and coupled intrinsic kinetics, along with mass transfer equations and the wetting of the catalyst particles. The model was implemented using Aspen Custom Modeler® (20 Crosby Dr. Bedford, MA 01730, EE. UU.) to study the reactor behavior in terms of conversion. The results show the profiles of different variables throughout the reactor and presen...
Advance Journal of Food Science and Technology, 2018
An experimental procedure was carried out to maximize Chaetoceros gracilis growth. Chaetoceros gr... more An experimental procedure was carried out to maximize Chaetoceros gracilis growth. Chaetoceros gracilis, marine microalgae, is considered for feeding fisheries with no GMO (Genetically Modified Organisms) to avoid human health hazards. Furthermore, following United Nations Resolution on water, the microalgae is grown in photobioreactors due to its low water usage. To maximize the microalgae growth, an experimental design was carried out to analyze the effects of Light Intensity, CO2 supply per day, Sparger type, Photoperiod and Inlet airflow, pH and water temperature were monitored but not controlled. It was found that Light intensity and CO2 supply per day have statistical significance. Out of three possible scenarios, 1700 lux and 80 gr/day of CO2, leads to a cell density at day three of 310×10 4 cel/mL which represents 20% more of the density attained in day two under bag (standard) growing conditions. It was also found that water Ph has also a strong effect over cell density.
Planing boat dynamics are a complex phenomenon and the maneuver forces acting on these kind of hu... more Planing boat dynamics are a complex phenomenon and the maneuver forces acting on these kind of hulls are difficult to predict. In the current work, a mathematical model of a two-dimensional impact with three degrees of freedom (3DOF) is developed. The model was used to study wedge sections with knuckles, the vertical, horizontal, and rotational motion are considered. Pressure distribution, forces, and motion during the impact, considering both free fall and forced motion, are evaluated. The commercial CFD (Computational flow dynamics) software Star-CCM+ V9.06 was used to validate the formulation. Simulations with one, two, and three degrees of freedom were carried out, and the results were compared with CFD simulations, experimental data, and numerical solutions by others authors. The results show a good agreement with the authors. The model is extended to three dimensions applying slender body theory, and the forces in the hull are computed. The formulation allows evaluating the se...
This work analyzes the use of palm kernel shells (PKS) produced by the Colombian palm oil mill in... more This work analyzes the use of palm kernel shells (PKS) produced by the Colombian palm oil mill industry, for purposes of fueling a commercial downdraft fixed bed gasifier (Ankur Scientific WGB- 20) designed to operate with wood chips. Operational parameters such as hopper shaking time, ash removal time, and airflow were varied in order to get the highest gasifier performance, computed as the ratio between producer gas chemical energy over biomass feeding energy. Experiments were carried out following a half fraction experimental design 24-1. Since these parameters affect the equivalence ratio (ER), behavior indicators were analyzed as a function of ER. It was found that the shaking time and airflow had a significant effect on higher-heating-value (HHV) and process efficiency, while the removal time is not significant. The highest performance for palm shell was reached at ER=0.35, where the resulting gas HHV and process efficiencies were 5.04 MJ/Nm3 and 58%, respectively.
In this article, data from a 3.5kW mini split air conditioning is presented. A screening 2 3 desi... more In this article, data from a 3.5kW mini split air conditioning is presented. A screening 2 3 design experiment was performed to evaluate the effects of indoor air temperature, absolute humidity and evaporator fan speed in the performance of the air conditioning. This dataset also includes noise factors as outdoor air temperature, fans energy consumption and response as indoor air exit conditions.
The Goswami cycle is a cycle that combines an ammonia–water vapor absorption cycle and a Rankine ... more The Goswami cycle is a cycle that combines an ammonia–water vapor absorption cycle and a Rankine cycle for cooling and mechanical power purposes by using thermal heat sources such as solar energy or geothermal steam. In this paper, a theoretical investigation was conducted to determine the performance outputs of the cycle, namely, net mechanical power, cooling, effective first law efficiency and exergy efficiency, for a boiler and an absorber temperature of 85 °C and 35 °C, respectively, and different boiler pressures and ammonia-water concentrations. In addition, an experimental investigation was carried out to verify the predicted trends of theoretical analysis and evaluate the performance of a modified scroll expander. The theoretical analysis showed that maximum effective first law and exergy efficiencies were 7.2% and 45%, respectively. The experimental tests showed that the scroll expander reached a 30–40% of efficiency when boiler temperature was 85 °C and rectifier temperatu...
A 2D computational fluid dynamics simulation was carried out using a multiphase flow model with a... more A 2D computational fluid dynamics simulation was carried out using a multiphase flow model with an Eulerian-Eulerian approach for a microalgae culture in an airlift column photobioreactor. Simulation was performed for a 0.0625 l/l culture •min inlet airflow. Air, water and microalgae velocity contours showed less gas phase present in the downcomer than in the riser, suggesting the necessity of vigorous mixing in the ascendant portion if homogeneous water and solid flow is to be achieved. Air velocity is smaller in the downcomer (shorter velocity vectors) than in the riser. Water velocity vectors point always in the expected direction, down in the downcomer and up in the riser. Microalgae paths, perhaps due to the small size of the microorganisms, follow the water velocity vectors. As there are fewer hydraulic restrictions to the liquid phase in the riser, a large amount of energy is dissipated by gas-liquid interactions. In the downcomer region, the gas phase is almost nonexistent, and bubble collisions are almost nonexistent as well. A quasi-stagnation zone was found at the lower section of the downcomer, showing that the design requires improvement. Finally, the turbulent kinetic energy is larger at the top and middle region of the riser; meanwhile, it is lower at the downcomer. Similar results were observed for the energy dissipation rate.
The 2D impact phenomenon in calm water, considering symmetric entry with vertical velocity is stu... more The 2D impact phenomenon in calm water, considering symmetric entry with vertical velocity is studied. The analysis was performed by using commercial STAR-CCM+ computational fuid dynamics software. Thee results obtained from the simulations are pressure distribution and force during impact. The study was carried out for typical planning of boat sections. The results are compared with models and data obtained from some authors and they present very good agreement.
This paper analyzes the feasibility of applying model predictive control strategies for mitigatio... more This paper analyzes the feasibility of applying model predictive control strategies for mitigation of the auto-ignition phenomenon, which affects the performance of spark-ignition internal combustion engines. The first part of this paper shows the implementation and experimental validation of a two-dimensional model, based on thermodynamic equations, to simulate operating conditions in engines fueled with natural gas. Over this validated model, several control strategies are studied in order to evaluate, through simulation analysis, which of these offer the best handling capacity of the auto-ignition phenomenon. In order to achieve this goal, multivariate control strategies are implemented for a simultaneous manipulation of the fuel/air ratio, the crank angle at ignition, and the inlet pressure. The controlled variable in this research is the temperature at the ignition point. This temperature is obtained through an estimation based on pressure in the combustion chamber at that poin...
This paper studied, through an experiment design, the significance of particle size, air speed an... more This paper studied, through an experiment design, the significance of particle size, air speed and reactor arrangement for palm shell micro-gasification process in order to optimize the heating value of the syngas obtained. The range of variables was 8 to 13 mm for particle size, 0.8–1.4m/s for air velocity, and updraft or downdraft for the reactor type. It was found that the particle size and air velocity factors were the most significant in the optimization of the output variable, syngas heating value. A heating value of 2.69MJ / Nm3 was obtained using a fixed bed downdraft reactor, with a particle size of 13 mm and 1.4 m/s for air speed; verification of the optimum point of operation under these conditions verified that these operating conditions favor the production of a gas with a high energy value.
institución: Biotecnología & Bioingeniería Core S.A, diseñaron un dispositivo compacto y portátil... more institución: Biotecnología & Bioingeniería Core S.A, diseñaron un dispositivo compacto y portátil para terapia respiratoria CPAP en niños prematuros, que resulta innovador frente a los que existen actualmente en el mercado. Desar rollo de dispo sitivo comp acto y portá til para terap ia CPAP de burbu ja en neon atos Invest igador es princi pales
Volume 4: Heat and Mass Transfer Under Extreme Conditions; Environmental Heat Transfer; Computational Heat Transfer; Visualization of Heat Transfer; Heat Transfer Education and Future Directions in Heat Transfer; Nuclear Energy, 2013
A computational simulation of the thermo hydraulic performance of a trapezoidal Off Set Strip Fin... more A computational simulation of the thermo hydraulic performance of a trapezoidal Off Set Strip Fin (OSF) is performed. The simulations are carried for Reynolds number ranging from 300 to 9000 considering three-dimensional conditions (3D). Calculations were developed assuming a constant flow. Colburn factor j, and the friction factor f, were calculated. Uniform temperature condition is assumed at the solid surface and at the inlet. The results have been compared with studies made by Kays and London, (1984), Manglik and Bergles (1990), and Muzychka and Yovanovich, (2001). According to the obtained results, it can be concluded that Computational Fluid Dynamics (CFD) is able to explore the behavior and performance of this kind of fin, showing that the hydraulic performance is well represented by correlations widely used in literature, while thermal performance seems to be under predicted.
The thermal performance of building materials used in Colombia is not currently characterized, wh... more The thermal performance of building materials used in Colombia is not currently characterized, which is essential to obtain the necessary information for an architectural design based on energy efficiency. The determination of materials thermal properties, as well as thermal and energy performance of building materials commonly used in Colombia are the main challenges for this research. The proposed methodology implies the experimental determination of the different materials thermal properties through the design and construction of an experimental device capable to accommodate different materials configurations. This will allow us to obtain relevant information to develop the government’s energy standards for quality building materials and quality policies for private companies. Among others are included: the Environmental Seal for Sustainable Building, which is currently being developed by the Colombian Council of Sustainable Building (CCCS); the Colombian standard for thermal systems applications in buildings (RITE) currently being developed by the Colombian Association of Air Conditioning and Refrigeration (ACAIRE); and policies for national sustainable buildings that were included in the National Development Plan 2010–2014 and 2015–2019.
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