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The present paper develops a methodology to choose the best connection scheme for traction substations of a Massive Electrical Railway System (MERS) and distribution substations in urban areas using graph theory and economical optimization.

Abstract Small-scale hydroelectric plants, primarily run-of-the-river designs, are regularly subjected to hard particle wear and cavitation erosion due to the wide range of operating points. Depending on the severity of the operating conditions and erosion damage experienced by the machine throughout its service life, the operating companies of these facilities will be impacted. The impact will be technical, operational, logistical, and economic. A small-scale generation plant located in Amaime River in Colombia, is one such case, where severe wear occurs in the turbine components, with a consequent reduction of efficiency. In this study, the analysis of the erosion damage has been expanded and supplemented by computational fluid dynamics (CFD). From this approach, correlations between the wear rate and power output were obtained. Likewise and in conjunction with the computer estimates, a methodology to analyse the costs associated with wear based on historical data of operation was developed, creating a strategy of operation based on a stopping criterion that depends primarily on sediment concentration, turbinated flow, and wear level. The methodology optimizes the use of generators, which takes into consideration the revenue generation and the costs associated with operation and maintenance of pieces under conditions of intrinsic erosion wear in the facility.

The black liquor is a byproduct of the kraft pulping process that contains more than half of the exergy content in the total woody biomass fed to the digester, representing a key supply of renewable energy to the pulping process. In this work, the conventional scenario of the black liquor use (i.e., concentration and combustion) is compared with the black liquor upgrading (via) gasification process for ammonia production in terms of economics, exergy efficiency and environmental impact. The combined energy integration and exergy analysis is used to identify the potential improvements that may remain hidden to the energy analysis alone, namely, the determination and mitigation of the process irreversibility. As a result, the exergy efficiencies of the conventional and the integrated cases average 40% and 42%, respectively, whereas the overall emission balance varies from 1.97 to −0.69 tCO2/tPulp, respectively. The negative CO2 emissions indicate the environmental benefits of the proposed integrated process compared to the conventional kraft pulp mill.

espanolSe presentan los resultados de un estudio sobre la significancia y la optimizacion de algunas variables (granulometria, velocidad de aire, contenido de biomasa y disposicion del reactor) en el poder calorifico del gas de sintesis obtenido de la gasificacion de biomasa (carbon vegetal y cuesco de palma africana). Mediante un diseno de experimento se evaluaron las cuatro variables que oscilaban entre 8-13mm para la granulometria, 0.8-1.4m/s para la velocidad del aire, 0-100 para el contenido de biomasa y ascendente-descendente para la disposicion del reactor. Se encontro que los factores correspondientes a la granulometria y el contenido de biomasa resultan ser los mas significativos en el poder calorifico del gas. Un poder calorifico maximo de 3.84MJ/Nm3 se obtuvo con la disposicion descendente del reactor, alimentacion de carbon vegetal con granulometria de 13mm y suministro maximo de flujo de aire. La verificacion del punto optimo de operacion mostro que tales condiciones de operacion favorecian la produccion de un gas con un alto poder calorifico. EnglishThe results of study on the significance and the optimization of some variables (particle size, air flow, biomass content and reactor disposition) in the calorific value of the synthesis gas obtained by gasification process of biomass (vegetal coal and biomass African palm) is presented. The four variables ranged from 8-13mm for the particle size, 0.8-1.4m/s for air flow, 0-100 for biomass content and updraft-downdraft disposition for the type of reactor were evaluated by an experimental design. It was found that the particle size and biomass content are the most significant factors to maximize the output calorific value of syngas. A maximum calorific value of 3.84MJ/Nm3 was obtained using the downdraft reactor with 13mm particle size and maximum air flow supply. The verification of the optimum operating point under these conditions showed that such operating conditions favored the production of a gas with high calorific value.

Currently Smart Grids are considered as an optimum model for energy supply. It improves the efficiency, reliability and availability of the electricity supply. It uses structures to achieve compliance with interoperation that are used across the entire network. To achieve this, special devices are distributed through the entire grid. A RMU (Ring Main Unit) is a device that makes measurements of electrical variables of the grid and sends wirelessly information to a central station MTU (Master Terminal Unit). The RMU has the capacity to detect failures and perform control by disconnecting the grid. In this article, it is shown the design and manufacture of a scale RMU.

This work is the result to the study a different systems of exhaust pipes. The manufacturers of motorbike use a system with several volumes to reduce noise and use a catalyst to reduce emissions. In contrast, the manufacturers of exhaust system decided made a system using a perforated pipe and a rock wool to noise reducing. This system changes the pressure drop and temperature of exhaust gases and, therefore, request a different composition of catalyst.In this communication, it is shown the tests released in a test bench according with the cycle WLTC and the limits are the defined for EURO3. Where, we have changed the type of catalyst, the diameter of the end pipe and the calibration of electronic control unit of engine in order to measure following the test of homologation.The results of the different experiments indicate is very important the pressure drop in the replace exhaust system must be similar to the original system. The composition of the catalyst and the operating temperature are critical to reduce the emissions and the calibration of engine is the main influence. Keywords: Exhaust systems, Catalyst, Regulatory emissions, WLTC

Abstract The effect of the injection of externally sourced carbon dioxide (CO2) on the stability of the flameless combustion regime was evaluated numerically and experimentally, taking temperature uniformity and pollution emissions (NO and CO) as criteria. The flameless combustion regime was studied in a lab-scale furnace fueled with natural gas (NG) at a thermal power of 20 kW based on the low heating value (LHV). The CO2 was injected into the lower part of the furnace to directly affect the reaction zone. Computational fluid dynamics (CFD) simulations were performed using the ansys-fluent software. The models used to describe the turbulence, the radiation heat transfer, and the turbulence–chemistry interaction were the standard k–ɛ model, discrete ordinate model (DOM), and eddy dissipation concept (EDC) model, respectively. The NG oxidation was described with a seven-step global reaction mechanism with the EDC model. Three excess air conditions were analyzed, 20%, 25%, and 30%, combined with various CO2 injection flows. At 30% excess air, the flame exhibited destabilization without any CO2 injection. Adding CO2 attenuates the destabilization because of the dilution effect. Increasing either the CO2 or excess air flow resulted in a considerable decrease in the global temperature of the process, consequently producing an increase in CO emissions and a decrease in NO emissions. Finally, for the conditions studied, increasing the mass flow of externally sourced CO2 did not destabilize the flameless combustion regimen. This result shows the potential of the implementation of flameless combustion in industrial processes where CO2 is releasing as a result of a reaction external to the combustion process, such as cement, ammonia, or lime production among others.

This paper analyses the behaviour of the demand curve in the residential sector from Bogota, Colombia, based on changes in the electric energy consumption behaviour of users. Initially, a survey divided in analysis units focused on obtaining the main characteristics of residential energy consumption was conducted. Using this information, a stochastic model was designed and developed in order to determine how changes in consumption habits during specific periods of the day influence the demand projection for a residential sector. A base scenario for the users of the selected population group was established from measurements in 18 houses and in the common point of a building, and the average energy consumed was 168.86 kWh/month. Through simulations using a system dynamics software, 12 scenarios were established. Consumption habits of users were modified in relation with periods and appliances, concluding that it is necessary to apply a set of strategies to encourage actions for changing the consumption habits of residential users, which has to be provided by government policies relevant to the energy area.

Spain has been pinpointed as one of the European countries at major risk of extreme urban events. Thus, Spanish cities pursue new urban plans to increase their resilience. In this scenario, experiences in the implementation of Sustainable Urban Drainage Systems (SUDS) have increased substantially. Nevertheless, few cities have developed a global urban strategy for SUDS, lacking, in many cases, a method to identify strategic areas to maximize their synergetic benefits. Furthermore, there is still a need for a holistic Multicriteria Decision Analysis (MCDA) framework that considers the four pillars of SUDS design. The city of Gijón, NW Spain, has been selected as a case study due to its environmental and climatic stresses. This research presents the methodology developed for this city, which aims to analyze the need for SUDS implementation throughout the identification of strategic areas. With this aim, a combination of Geographic Information System (GIS) software and the MCDA Analytical Hierarchical Process (AHP) were proposed. The results show the potential for SUDS’ implementation, according to nine criteria related to the SUDS’ design pillars. We found that the areas where the implementation of SUDS would bring the greatest functional, environmental and social benefits are mainly located in consolidated urban areas.

This paper presents a description of the regulations implemented in Colombia, from Law 1715 of 2014 until nowadays. The main decrees established for the development of projects with non-conventional sources of energy are described, as well as the steps to follow in order to obtain the tax benefits allowed by this law. The different scenarios for the development of photovoltaic projects are also identified, both by type and by size, describing the different procedures to be followed as well as the possible advantages and/or disadvantages of each one.