No abstract

In this article, a thermodynamic, exergy, and environmental impact assessment was carried out on a Brayton S-CO2 cycle coupled with an organic Rankine cycle (ORC) as a bottoming cycle to evaluate performance parameters and potential environmental impacts of the combined system. The performance variables studied were the net power, thermal and exergetic efficiency, and the brake-specific fuel consumption (BSFC) as a function of the variation in turbine inlet temperature (TIT) and high pressure (PHIGH), which are relevant operation parameters from the Brayton S-CO2 cycle. The results showed that the main turbine (T1) and secondary turbine (T2) of the Brayton S-CO2 cycle presented higher exergetic efficiencies (97%), and a better thermal and exergetic behavior compared to the other components of the System. Concerning exergy destruction, it was found that the heat exchangers of the system presented the highest exergy destruction as a consequence of the large mean temperature difference between the carbon dioxide, thermal oil, and organic fluid, and thus this equipment presents the greatest heat transfer irreversibilities of the system. Also, through the Life Cycle Analysis, the potential environmental impact of the system was evaluated to propose a thermal design according to the sustainable development goals. Therefore, it was obtained that T1 was the component with a more significant environmental impact, with a maximum value of 4416 Pts when copper is selected as the equipment material.

Se hizo una relación de las empresas ladrilleras dedicadas a la producción de materiales cerámicos en el municipio de Ocaña, identificando tipo de horno, capacidad y producción. Luego se seleccionó una muestra de siete empresas ladrilleras, a las que se les practicó un muestreo isocinético donde se determinó la concentración de emisiones reguladas por la resolución 909 de junio de 2008 (porcentajes de oxígeno, monóxido de carbono, dióxido de carbono y óxido de nitrógeno),finalmente se hace un análisis del cumplimiento  de los requisitos establecidos en la normativa ambiental vigente para emisión por fuentes fijas en las ladrilleras a los hornos en mención ,de lo que se establece que las empresas seleccionadas cumplen con los requisitos establecidos en la normatividad ambiental Colombiana.

Este trabajo tiene como propósito la evaluación de la adopción del modelo Constructivista Social, con el fin de validar la hipótesis de que con el avance de los semestres académicos aumenta la incorporación de estrategias pedagógicas que permiten la mejor adopción del enfoque Constructivista Social por parte de los docentes de la UFPSO. El estudio se plantea mediante una metodología descriptiva-evaluativa teniendo en cuenta la población de 362 docentes entre planta y catedráticos, de la cual se toma una muestra de 76 profesores. Se definen como variables el Rendimiento Académico y las Estrategias Pedagógicas, se generan varios inter grupos con cada facultad, se contempla un plan que incluye el análisis comparativo y correlación de Pearson entre facultades. Palabras clave: Estrategias Pedagógicas, Modelo Pedagógico, Rendimiento Académico

Contexto: Las propiedades finales de un bloque cerámico utilizado para mampostería dependen de las temperaturas a las que fue cocida la pasta. Dichas propiedades son relevantes, toda vez que en función de ellas será el comportamiento estructural de los muros en una edificación.Objetivo: El propósito del presente trabajo es determinar la relación entre las propiedades finales del bloque cerámico y las temperaturas a las que fue cocido, considerando la rapidez con que estas varían en el horno.Método: Se implementó un sistema para registrar temperaturas en el horno utilizando Labview, se consideró la velocidad de incremento de temperatura según la curva ideal para la cocción de bloques, que fueron clasificados al interior del horno, y se tomaron muestras de producto para determinar las propiedades siguiendo las normas NTC 4017 y NTC 4205.Resultados: Se determinó la tasa de absorción inicial de agua (TIA), absorción a las 24 horas de inmersión, resistencia a la compresión y módulo de rotura (MR). Mediante un análisis de regresión lineal múltiple se encontró relación existente entre la TIA, la velocidad de incremento de temperatura y el MR.Conclusiones: Los bloques que superaron los 1000 °C poseen el mayor módulo de rotura (con valor de 1,54 MPa). Sin embargo, se encontró la mayor tasa de absorción inicial (0,37 g/cm2/min) y la mejor resistencia a la compresión (7,28 Mpa) en los bloques que fueron cocidos a menor temperatura. Las propiedades no son las adecuadas dado que en el proceso de cocción no es controlada la temperatura ni el tiempo.

In Colombia, the most widely used means of transport today are motorcycles, which have become increasingly numerous, bearing in mind that they are subject to laws and regulations imposed by the country’s mobility, transit and transport agencies, the use of helmets is mandatory for drivers and passengers, safety measures are monitored, the hull must be certified and meet the required technical standards; whereas its role is to protect people in the event of accidents, regulations require that the helmet be completely closed to protect the entire head and chin; the design of the helmet allows air entry and there is no concentration of temperature inside, all this is done by implementing air inlet and outlet ducts, which circulate air when the motorcycle is in motion, unfortunately this does not happen due to the accumulation of temperature in the back of the helmet that makes the user feel tired and uncomfortable. This research proposes the development of a prototype portable cooling system for motorcycle helmets by the physical principle of heat transfer, by using Peltier cells, to have low production cost, optimal operation, and low energy consumption thanks to natural air flow.

This article aims to show direct, diffuse, and total solar radiation in the departments of La Guajira, Magdalena, and Cesar, located on the Caribbean coast of Colombia. In addition, data on climatic variables such as temperature, pressure, and relative humidity measured through different sensors located in these meteorological stations are presented. The data obtained by these stations correspond to measurements from 1993 to 2013 allowed the estimation of the parameters of the total, direct and diffuse solar radiation for each department, by mean of the Bird and Hulstrom model and parameterizations of the Mächler and Iqbal model. In addition, five climatological scenarios that could occur using these data were calculated.

In many devices such as refrigerators, ovens, industrial kitchens, integrated circuits among others, where heat transfer is involved, it is important to know the thermal behavior of the material and the geometric model (cylindrical, spherical, etc.), with which such equipment will be built, to subsequently perform analysis of the parameters evaluated and thus enhance their efficiency. For this reason, it is important to know variables such as thermal conductivity, wall thickness, material, and geometry for new generation equipment. As a result, this work involved the construction of a test bench for the analysis of thermal conductivity in insulating materials, which began with the selection of the components that made up the device, such as resistors, types of thermocouples, specimen geometry, sensors, and finally, the construction of a data acquisition and analysis control system using Arduino and Labview. Subsequently, a device was obtained to measure the temperature in the cylindrical walls with different granular materials. This project was developed in an innovative way, where the thermal behavior of non-pure agglomerated granular materials will generate research in the study area, with the purpose of implementing it in different projects in which heat transfer is involved.