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Air conditioning is an essential topic in heat transfer phenomena because it is widely applied in homes and industries. It has an incredible amount of applications ranging from health care to food shelf life. With the enhancement of technology, it is necessary to create new devices that increase the efficiency of air conditioning. Hence, it is required to evaluate the trend of study of this topic to help researchers to get the best research direction that promotes the acquisition of better experimental results. For that reason, it was collected a total of 2431 documents about air conditioning from the Science Citation Index Expanded during the period from 2008 to 2019. Next, it was used HistCite to analyze the yearly output, country, institution, citation impact, and citation relationships in this field of study. Results suggest that the research of air conditioning had an increase during the studied 11-year period. The countries with the highest research output were China, The USA, and Japan, and the institutions with the highest research output were the National Natural Science Foundation of China and the Hong Kong Polytech University. The journals with the largest number of articles were Energy and Buildings with 195 publications and Applied Thermal engineering with 164 papers.

Greater incorporation of wind energy into power systems has necessitated the development of accurate and reliable techniques for wind speed forecasting. However, although there are multiple studies, none are set up for the Colombia Caribbean coast. This is a disadvantage because the potential of wind resources in this region is greater than the hydroelectric potential of the whole country, but all this potential has yet to be developed. In this paper, based on time series, Autoregressive Integrated Moving Average (ARIMA), and Multiple Regression with Ordinary Least Squares (OLS) in the study, two models are proposed and their performance for wind speed prediction is compared. The data were collected in the meteorological station located in the experimental farm of the Atlantic University, in Barranquilla, Colombia, and variables analyzed included wind speed, wind direction, temperature, relative humidity, solar radiation, and pressure. The results of the two approaches indicated that among all the involved models, the ARIMA model has the best predicting performance. Also, it is essential to highlight that through this work, decision-makers would explore the local wind potential, allowing for the possibility of predicting future wind speed, and thus giving them the ability to plan the production and the interaction of other sources of energy.

This paper presents a bibliometric study of the nuclear energy research output from 2008 to 2018, by mean of the Web of Science (WoS) database. From the 2545 papers published in the period studied, bibliometric indicators were calculated to identify the tendency of this energy source, such as the number of publications by countries, institutions, authors, main keywords reported and the identification of the most cited articles. The results shown the scientific paper as the document type with a more significant number of publications from the total considered (83.4%), and the country with the highest h-index value was the United States, which is also the country with the highest production of articles with a total of (643), followed by China and Germany. An increase in the research outlet was presented in USA (213%) and Germany (182 %) from 2013 to 2017, which is close with the number amount of publication developed by these countries under the figure of international collaboration. Also, the Chinese Academy of Science was the institution with the highest number of publications (79), and the top institution with publications under international network. The results allow to identify the main stakeholders in the nuclear energy research output and determine projections and tendencies on new and complementary topics in this field of study.Keywords: research trend, nuclear energy, bibliometric study, collaboration network, h-index.JEL Classification: Q42DOI: https://doi.org/10.32479/ijeep.8515

This study investigates the current situation of electricity generation from renewable energy sources in Colombia and the energy situation of the Colombian population. In general, it was demonstrated that Colombia has potential in renewable sources, mainly in solar energy, wind, and biomass. However, technical, economic and social barriers such as the lack of human capital, policies focusing on conventional technologies, high investment costs, as well as technological limitations due to the instability, intermittency and low efficiency inherent in renewable energy sources, have impeded their development. Despite the promotion of these renewable sources through Law 1715, greater commitments are needed to implement and improve energy policies, as well as investments in precise research on Colombia's energy potential and new existing technologies. For the technological limitations, this study proposes the use of energy storage systems, by means of battery systems or the use of biomasses such as chicken feather fibers and the peel of the oil palm for the production, storage and use of hydrogen as an energy gas. This with the aim of eliminating the instability and intermittency of renewable energy sources. Additionally, the advantages of thermoelectric devices are presented, which, coupled to photovoltaic cells allow increases of 2 to 10% in the efficiency of solar panels. In addition, the features of these devices allow you to generate electricity from the waste heat of virtually any process. This quality could increase in industrial sectors in Colombia such as the steel industry, the ceramics sector, the cement industry, and in the recovery of heat from the exhaust gases of diesel generators. The latter is used mainly in non-interconnected zones. This is intended to improve the efficiency of the processes, as well as the reduction of fuels in the case of diesel generators.

Given the growth in energy demand, the limited energy resources, and the high environmental impact of energy generation from fossil fuels, it is vital to find methods to obtain save energy costs in differentsectors, such as residential, industrial,transportation sector, and domestic. This paper presents a methodology that allows the implementation of an energy management system following the guidelines of the ISO 50001 standard. Agap analysis was performed to determine the position of the organization with respect to the requirements ofthe standard,andthe next step was the inspection of the plant to find opportunities for improvement that would lead to energy optimization. From the results, six equipmentwasthe cause of the 82% of the energy consumption in the production process, and some recommendation was proposed with the aim to optimize energy consumption. A methodology is proposed for the standard implementation, which can be implemented by different organizations from different fields to achievesavings in energy costs in the plant.Some relevant actions to improve the energy performance of the plant were proposed, such as the optimization of the compressed airsystem,the reduction ofpotential numbers of leakage, and the reduction ofthe working pressure of the system. Dado el crecimiento en la demanda de energía, los recursos energéticos limitados y el alto impacto ambiental de la generación de energía a partir de combustibles fósiles, es vital encontrar métodos para obtener ahorros en los costos de energía en diferentes sectores, como el residencial, el industrial y el transporte. nivel doméstico Este artículopresenta una metodología que permite la implementación de un sistema de gestión de energía siguiendo las pautas de la norma internacional ISO 50001. Donde, en primer lugar, se realizó un análisis de brechas para determinar la posición de la organización con respecto a los requisitos que se encuentran en la norma, el siguiente paso fue la inspección de la planta para encontrar oportunidades de mejora que condujeran a la optimización energética. De los resultados, seis equipos fueron la causa del 82% del consumo de energía en el proceso de producción, y se propusieron algunas recomendaciones con el objetivo de optimizar el consumo de energía. Se propone una metodología para la implementación estándar, que puede ser implementada por diferentes organizaciones de diferentes campos para lograr ahorros en los costos de energía en la planta.Se propusieron algunas acciones relevantes para mejorar el rendimiento energético dela planta, como la optimización del sistema de aire comprimido, la reducción del número potencial de fugas y la reducción de la presión de trabajo del sistema.

This study investigates the influence of biodiesel blends produced from agro-industrial residues of palm oil (Elaeis guineensis), on the performance and emission characteristics of a small diameter single-cylinder diesel engine. The engine tests have been performed at three different loads with a constant speed of 3600 rpm. Experimental results have showed that the blends of biodiesel PB5 and PB10 cause a consumption of 1.12% and 2.45% higher than diesel. The addition of biodiesel from palm oil residues has allowed the reduction of CO, CO2, and HC emissions by 28.6%, 12.6%, and 14.3%. However, biodiesel has caused an increase in NOx emissions and smoke density. The evaluation of the thermal efficiency of the brake has showed a difference of 2.4% and 3.7% for PB5 and PB10 compared to conventional diesel. Similar efficiency compared to diesel and significant reductions in CO, CO2, and HC emissions, show that biodiesel blends produced from palm oil agro-industrial wastes have the potential to replace partially the diesel content in the fuel, thus contributing to the reduction of engine emissions and reducing the environmental pollution caused by this type of waste.

This article presents a sensitivity analysis based on a validated model of average value in natural gas generation engines under the phenomenologically based semi-physical modeling methodology, which includes both the cylinder, exhaust, and intake manifold and it can define the average operational variables and thermochemical properties of exhaust gases as a function of the variables instrumented in this type of engine at the industrial level. The results for a month of operation showed errors no greater than 5% in the temperature at the entrance of the cylinders (Temperature 6), while the power, load temperature and load pressure of the model presented deviations of less than 2% from the measured data. Additionally, the results of the sensitivity analysis evidenced that the main variable affecting most of the parameters under study is the flow of gas entering the engine, which causes a variation of 12.3% in Temperature 6, and 22.4% in electrical power. Next, the second most influential variable is Lambda, significantly affecting the efficiency by 8%. Finally, there is the RPM of the engine in its work cycle, which affects the temperature of the cylinder outlet by 34.5%. This means that when the flow of fuel in the engine decreases, there will be significant operational changes in the engine, and therefore in the thermal availability of exhaust gases.

This article presents the application of a new educational thermodynamic software called MOLECULARDISORDER, based on graphical user interfaces created in Matlab&reg, to promote critical thinking in youth engineering students, by means of the energy and entropy balance application in different systems. Statistics of the results obtained by the youth students are shown to determine the influence of the software in a regular course in thermodynamics to promote critical thinking. Two case studies were done by the students, where parameters such as temperature of the fluid and metal surfaces, pressure of the system, mass of the fluid and solid, volume, and velocity of the fluid are used to obtain output variables such as enthalpy, entropy, changes in entropy, entropy production, and energy transfer in the chosen system. Four cognitive skills were considered to evaluate the cognitive competencies of interpreting, arguing and proposing, and interacting with the different graphical user interfaces, these cognitive skills (CS) were argumentative claim (CS1), modeling (CS2), interpreting data/information (CS3), and organization (CS4). Student&acute, s T-test was used to compare the degree of difficulty of each criterion. The case studies were evaluated first without using the software and then with the use of the software to determine the significant effect of the software quantitatively. A population of 130 youth students was taken to perform the statistical analysis with a level of significance of 5%. With the help of the software, the students obtained an improvement when performing case study 1 since the p-value obtained was 0.03, indicating that there are significant differences between the results before and after taking the software. The overall averages of the grades for case study 1 had an increase after using the software from 3.74 to 4.04. The overall averages for case study 2 were also higher after taking the software from 3.44 to 3.75.

The quality of the energy transformation processes focuses on improving the energy efficiency of the components used in a thermodynamic cycle with the aim to upgrade the application of the resources needed to produce energy in power generation plants. Due to the great importance of thermal analysis in the kinetic energy transformation of a fluid into electrical energy through combined Rankie cycles applied on industrial processes, this paper proposes an energetic and exergetic analysis of a heat exchanger used as a steam surface condenser with the aim to reduce the fuel consumption used by a steam turbine and to establish parameters that define the performance of the shell and tube heat exchanger using computational tools of thermal analysis. An experimental model has been used to validate the numerical analysis developed in a virtual environment. MATLAB software has been used as a numerical tool to develop the matrix manipulations written in .m code that define the thermal analysis of the equations that describe the behavior of the combined regenerative Rankine cycle power plant. Numerical data generated in the numerical model with MATLAB has been compared with the experimental model of the steam surface condenser. A good agreement has been reached between the CFD analysis and the experimental model of the steam surface condenser.

Background/Objectives: To take into an account the effects of compressibility when studying the flow of any fluid, it is necessary to define a series of additional parameters in the nozzle analysis, which is a complex job to do in a manual strategy, leaving as a suitable option the use of numerical methods programmed in a commercial software (such as MATLAB®). Methods: Variations were made in compressible flow parameters, such as initial pressure and temperature, and the Mach number, to study their influence over the pressure profile of the air inside a nozzle. Findings: The results show a low influence of the temperature over the pressure profile, a medium to high influence from its intake pressure, and a close relationship with the Mach number, getting even higher pressure drops when it only increases a bit. Application: To predict the behavior of the fluid flow through a nozzle, and to establish design and simulation criteria for these, when subjected to a particular application. Keywords: Compressible Flow, Isentropic Process, Mach Number, Nozzle, Subsonic Flow

Background/Objectives: To make implementation of a thermodynamic diagnostic model to determine the rate of heat release in low displacement Diesel engines so that the performance of the combustion process can be quantified and sub-models of heat transfer can be adjusted; so that it can be applied in subsequent predictive modeling. Methods: With the pressure data in the combustion chamber and the set of variables composed of the pressure and temperature in the admission, fuel consumption, speed of rotation, injection pressure, compression ratio and environmental conditions, a thermodynamic model is defined. It allows quantifying how the heat release process occurs in the combustion process. Findings: The results allow verifying the influence of the compression ratio on the heat release process, finding that the rate of heat released increases with the increase of the variable under study. Likewise, it is verified that the most pronounced difference between the release rates for different compression ratios studied is in the premix combustion zone. Application: This methodology can be used for the process of optimization and redesign of thermal engines, to maximize the output power for the same fuel and operational conditions. Keywords: Combustion, Compression Ratio, Diesel, Engine, Heat Released, Thermodynamic Model

Background/Objectives: The implementation of a methodology for the calibration of a force sensor, applied to a commercial-type FSR for a seat occupancy detection application in a vehicle. This methodology is basedon the use of an Arduino® board, to establish a direct conversion between the sensor output, and the measured variable, which in this case correspond to the force applied. Methods: With the study of the behavior of the sensor response when coupled with a conditioning circuit, and the following calibration of this, to program a direct conversion between the circuit output voltage and the force detected by the sensor. Findings: It was found that using the programming of the Arduino board, the force value given by the Arduino GUI, have a maximum deviation from the real ones of approximately 1%, which can be attributed to conversion issues, but for the application required, the system studied has a great potential to use. Application: To calibrate a FSR force sensor, using a circuit conformed by a conditioning signal system, the sensor and the transducer element between the sensor and the graphical interface on a PC. Keywords: Arduino, Calibration, Conditioning, Force-Sensing Resistor, Seat Occupancy Detection

Background/Objectives: The implementation of a novel method for the characterization of energy efficiency in centrifugal pumps based on the first law of thermodynamics is studied, with which the energy consumption of the turbomachine can be diagnosed. Methods: With the measurement of temperature and pressure at the inlet and outlet of the pump, energy efficiency is determined, without the need to measure electrical or mechanical parameters, which allows determining quickly on site if the pump is operated in an area of high efficiency. Findings: The results allow corroborating the high predictive capacity of the proposed methodology so that the trend is followed compared with efficiency data calculated by conventional methods. A deviation close to 1% was observed in the average efficiencies, compared with the developed method. Application: To develop an online diagnosis and energy assessment of Centrifugal Pumps based on the thermodynamic Approach Method. Keywords: Centrifugal Pumps, Energy Assessment, Energy Efficiency, On-Line Diagnosis, Thermodynamic Approach

This article presents the study of the surface roughness inside cylinders, machined by honing in industrial honing machines, with a detailed review of the variability of the values obtained in the measurement of the machined surface. The determination of the amount of measurement data on the cover is displayed to get characteristic mean values of the measured surface. For this reason, and due to the randomness of the surfaces machined by honing, an experimental study has been proposed to carry out this analysis, where the roughness has been measured with a roughness meter with a contact probe, since this type of instrument is widely used academically and especially industrially, and is apparently standardized by international standards such as ISO 3274 or ASME B46.1.

In the present investigation, the effect of main parameters for the development of parts in production such as feed rate and depth were evaluated, obtaining the machining costs depending on the characteristics of the material. The machining process used was that of turning in pieces with carbon steels and cast iron as the base material, varying the feed rate in a range between 0.2mm/tooth and 0.8mm/tooth and the depth between 1mm and 4mm allowing important parameters to be determined such as cutting speed and machine operating conditions to obtain a good final finish without affecting the surface of the piece and in production time required to optimize costs.

The reduction of the amount of pollution and toxicity by the manufacture of products has been a topic widely investigated by many international organizations, looking for an answer that help humanity to minimize the environmental impact. The main objective of this paper is to study the literature of Green engineering from 2007 to 2017 using bibliometric techniques for obtaining an overview of the production behavior of publications in this topic. The information was discharged and analyzed using tools such as Web of Science (WOS) and HistCite to get important results of the international contribution developing significant advances in this area. According to the results obtained, USA has been the most important country researching in this subject, providing 36.8% of the total publications. From the 257 publications, 60.9% were journal articles, where the Abstracts of papers of the American Chemical Society was the most relevant journal with 14 papers. Between 2014 and 2017 an important increase in the published production was presented, being 2016 the year with the most papers published with 15.6% of total investigations. In recent years, green engineering has been consider in many process on industries as a key tool to help the control of the greenhouse emissions, reducing the environmental impact providing some steps to achieve goals proposed for 2050 according to the ISO 50001 standard.Introducción.

The hybrid system is analyzed and optimized to produce electric energy in Non-Interconnected Zones in the Colombian Caribbean region, contributing both to the improvement in the reduction of greenhouse gas emissions and to the rational use of energy. A comparative analysis of the performance of these systems was carried using a dynamic model in real wind and solar data. The model is integrated by a Southwest Wind Power Inc. wind turbine. AIR 403, a proton exchange fuel cell (PEM), an electrolyze, a solar panel and a charge regulator based on PID controllers to manipulate oxygen and hydrogen flows in the cell. The transient responses of the cell voltage, current, and power were obtained for the demand of 200 W for changes in solar radiation and wind speed for all days of the year 2013 in the Ernesto Cortissoz airport, Puerto Bolívar, Alfonso Lopez airport and Simon Bolívar airport, by regulating the flow of hydrogen and oxygen into the fuel cell. The maximum contribution of power generation from the fuel cell was presented for the Simon Bolívar airport in November with a value of 158,358W (9.45%). A multi-objective design optimization under a Pareto front is presented for each place studied to minimize the Levelized Cost of Energy and CO2 emission, where the objective variables are the number of panel and stack in the PV system and PEM.&nbsp

This article shows the application of an energy management system and the calculation of energy efficiency indicators to a pyrotubular boiler, following the guidelines of the ISO50001 standard. The actual energy consumption indicators, the theoretical consumption index, the energy baseline and the efficiency index 100 were evaluated based on gas consumption and steam production data. As for the savings measure, a 20% reduction in gas consumption can be achieved by reducing the operational variability equivalent to 186,633 m3/month, thereby achieving a monthly savings of $70,920,717 COP and a large reduction in natural gas equivalent to a reduction in CO2 emissions (1,318,739.05 kg CO2/month). Also, the purges currently recorded in the boiler are higher than the recommended value for this equipment, and the excess air released varies between 6% and 11%, increasing the losses due to sensible heat. Three main implementations were applied to improve the energy performance of the steam boiler. The first saving implementation was the reduction of the generation pressure from 250 to 180 psig, achieving a lower gas temperature with a reduction of heat losses from the boiler, pipes and steam leakage losses, achieving a saving of 2% of the average natural gas consumption. The second implementation was the automation of the boiler purges, in accordance with the recommended value UNE-9075/85, achieving a total saving of 0.66%, and the third measurement allows on-line correction of the combustion air by direct measurement of O2, which maintains the measured oxygen value at 3%, which is the recommended value. With this practical and novel method energy performance indicator on the boiler, was increased the performance of the equipment, as well as the production costs and environmental impact reduction.Keywords: Energy Optimization, Steam Boiler, Energy Performance Indicator, ISO 50001 Standard.JEL Classification: Q42DOI: https://doi.org/10.32479/ijeep.8188

This article presents the analysis of the political, economic, social and technological aspects of the countries with the greatest development and generation of wind energy in the world, with the aim of studying the successes and disadvantages over the years and serve as a reference to a country like Colombia, which is in full technological development and is very interested in investing in new alternatives to the imminent ecological disaster resulting from polluting emissions. Colombia signs the Paris Agreement and immediately creates a large number of opportunities supported by state policies and economic investment, specifically in the construction of wind farms that guarantee a real alternative to the country's energy demand. Wind energy supplies 5% of the world's electricity, a contribution in which countries such as the United States, China, and Germany are the main producers. For this reason, it is necessary to study and analyze the factors that prevent the technological development of wind energy in Colombia, if it is considered a country with abundant resources in renewable energy sources and zero cost, a country that aspires to be a protagonist in the next 5 years according to the Ministry of Mines and Energy.