• Energy Research

This paper aims to present the real improvement opportunities of a simple organic Rankine cycle (ORC) as waste heat recovery system (WHRS) from the exhaust gases of a natural gas engine using toluene as the working fluid, based on the exergy and environmental point of view. From the energy and exergy balances, the advanced exergetic analysis was developed to determine the irreversibilities and opportunities for improvement. Since the traditional exergo-environmental analysis, it was found that the component with the greatest potential environmental impact associated with exergy (bF = 0.067 mPts/MJ) and per unit of exergy (ḂD = 8.729 mPts/h) was the condenser, while the exergy-environmental fraction was presented in the turbine (52.51%) and pump-2 (21.12%). The advanced exergo-environmental analysis showed that the environmental impact is more associated with the operational behavior of the components, with 75.33% of the environmental impacts being of endogenous nature, showing that the environmental impacts are generated to a reduced magnitude through the interactions between components. However, it was identified that much of the environmental impacts in ITC 1 could be reduced, with 81.3% of these impacts being avoidable. Finally, the sensitivity analysis results revealed that steel is the material of the components with the least environmental impact.

Cette étude étudie une méthodologie de carburant alternatif pour les moteurs diesel qui se concentrent sur l'influence de l'éthanol en tant qu'agent additif dans les mélanges de biodiesel dérivés des déchets liquides industriels d'huile de palme et de résidus d'huile de tournesol. Plus précisément, l'étude aborde les aspects pertinents des performances de combustion et des caractéristiques des émissions dans un moteur diesel monocylindre. Pour le développement expérimental, quatre carburants différents ont été testés : le diesel commercial, un mélange de biodiesel formé à partir de la matière résiduelle d'huile de palme et d'huile de tournesol (PB3SB2), deux mélanges avec une addition de 2%, et 4% d'éthanol dans le biodiesel produit (PB3SB2E2 et PB3SB2E4). Le moteur fonctionnait selon neuf modes de fonctionnement différents suivant les méthodologies de test internationales. Les résultats ont indiqué que l'incorporation d'éthanol dans le mélange de biodiesel PB3SB2 améliore l'efficacité thermique de 0,8 %. L'augmentation du rapport de mélange de l'éthanol à 4 % permet une amélioration supplémentaire de l'efficacité allant jusqu'à 1,2 %. L'analyse des émissions a montré que l'ajout d'éthanol inférieur à 4 % dans le mélange de biodiesel facilite la minimisation des niveaux de polluants de CO, CO2, NOx, HC et opacité de la fumée par rapport au biodiesel formé par les deux huiles résiduelles (PB3SB2). Dans l'ensemble, l'incorporation d'éthanol a réduit les niveaux d'émissions entre 7,5 et 13,87 % par rapport au PB3SB2. En conclusion, l'intégration du biodiesel et de l'éthanol en tant qu'additif apparaît comme une alternative prometteuse pour promouvoir un fonctionnement fiable et durable des moteurs diesel. Este estudio investiga una metodología de combustible alternativo para motores diesel que se centra en la influencia del etanol como agente aditivo en mezclas de biodiesel derivadas de los residuos líquidos industriales de aceite de palma y residuos de aceite de girasol. Específicamente, el estudio aborda aspectos relevantes del rendimiento de la combustión y las características de las emisiones en un motor diésel monocilíndrico. Para el desarrollo experimental, se probaron cuatro combustibles diferentes: diesel comercial, una mezcla de biodiesel formada a partir del material residual de aceite de palma y aceite de girasol (PB3SB2), dos mezclas con una adición de 2% y 4% de etanol en el biodiesel producido (PB3SB2E2 y PB3SB2E4). El motor funcionó bajo nueve modos de operación diferentes siguiendo metodologías de prueba internacionales. Los resultados indicaron que la incorporación de etanol en la mezcla de biodiesel PB3SB2 mejora la eficiencia térmica en un 0,8%. El aumento de la proporción de mezcla de etanol al 4% proporciona una mejora adicional de la eficiencia de hasta el 1,2%. El análisis de emisiones mostró que la adición de etanol por debajo del 4% en la mezcla de biodiesel facilita la minimización de los niveles contaminantes de CO, CO2, NOx, HC y opacidad del humo en comparación con el biodiesel formado por los dos aceites residuales (PB3SB2). En general, la incorporación de etanol redujo los niveles de emisiones entre 7.5 y 13.87% en comparación con PB3SB2. En conclusión, la integración del biodiesel y el etanol como agente aditivo surge como una alternativa prometedora para promover un funcionamiento fiable y sostenible en los motores diésel. This study investigates an alternative fuel methodology for diesel engines that focus on the influence of ethanol as an additive agent in biodiesel blends derived from the industrial liquid waste of palm oil and sunflower oil residues. Specifically, the study addresses relevant aspects of the combustion performance and emissions characteristics in a single-cylinder diesel engine. For the experimental development, four different fuels were tested: commercial diesel, a blend of biodiesel formed from the residual material of palm oil and sunflower oil (PB3SB2), two blends with an addition of 2%, and 4% ethanol in the biodiesel produced (PB3SB2E2 and PB3SB2E4). The engine operated under nine different operation modes following international testing methodologies. Results indicated that incorporating ethanol in the PB3SB2 biodiesel blend improves thermal efficiency by 0.8%. Increasing the ethanol mixing ratio to 4% provides a further efficiency improvement of up to 1.2%. The emissions analysis showed that the addition of ethanol below 4% in the biodiesel blend facilitates the minimization of pollutant levels of CO, CO2, NOx, HC, and smoke opacity compared to the biodiesel formed by the two residual oils (PB3SB2). Overall, ethanol incorporation reduced emissions levels between 7.5 and 13.87% compared to PB3SB2. In conclusion, integrating biodiesel and ethanol as additive agent emerges as a promising alternative to promote a reliable and sustainable operation in diesel engines. تبحث هذه الدراسة في منهجية الوقود البديل لمحركات الديزل التي تركز على تأثير الإيثانول كعامل مضاف في خلطات الديزل الحيوي المشتقة من النفايات السائلة الصناعية لزيت النخيل وبقايا زيت عباد الشمس. على وجه التحديد، تتناول الدراسة الجوانب ذات الصلة لأداء الاحتراق وخصائص الانبعاثات في محرك ديزل أحادي الأسطوانة. بالنسبة للتطوير التجريبي، تم اختبار أربعة أنواع مختلفة من الوقود: الديزل التجاري، ومزيج من الديزل الحيوي المتكون من المادة المتبقية من زيت النخيل وزيت عباد الشمس (PB3SB2)، ومزيجان بإضافة 2 ٪، و 4 ٪ إيثانول في الديزل الحيوي المنتج (PB3SB2E2 و PB3SB2E4). يعمل المحرك في تسعة أوضاع تشغيل مختلفة وفقًا لمنهجيات الاختبار الدولية. أشارت النتائج إلى أن دمج الإيثانول في مزيج الديزل الحيوي PB3SB2 يحسن الكفاءة الحرارية بنسبة 0.8 ٪. توفر زيادة نسبة خلط الإيثانول إلى 4 ٪ تحسينًا إضافيًا للكفاءة يصل إلى 1.2 ٪. أظهر تحليل الانبعاثات أن إضافة الإيثانول أقل من 4 ٪ في مزيج الديزل الحيوي يسهل تقليل مستويات الملوثات من ثاني أكسيد الكربون وثاني أكسيد الكربون وأكاسيد النيتروجين والهيدروكربون وشفافية الدخان مقارنة بالديزل الحيوي الذي يتكون من الزيتين المتبقيين (PB3SB2). بشكل عام، أدى دمج الإيثانول إلى خفض مستويات الانبعاثات بين 7.5 و 13.87 ٪ مقارنة بـ PB3SB2. في الختام، يظهر دمج الديزل الحيوي والإيثانول كعامل مضاف كبديل واعد لتعزيز عملية موثوقة ومستدامة في محركات الديزل.

This article presents a multivariable optimization of the energy and exergetic performance of a power generation system, which is integrated by a supercritical Brayton Cycle using carbon dioxide, and a Simple Organic Rankine Cycle (SORC) using toluene, with reheater ( S - C O 2 R H - S O R C ), and without reheater ( S - C O 2 N R H - S O R C ) using the PSO algorithm. A thermodynamic model of the integrated system was developed from the application of mass, energy and exergy balances to each component, which allowed the calculation of the exergy destroyed a fraction of each equipment, the power generated, the thermal and exergetic efficiency of the system. In addition, through a sensitivity analysis, the effect of the main operational and design variables on thermal efficiency and total exergy destroyed was studied, which were the objective functions selected in the proposed optimization. The results show that the greatest exergy destruction occurs at the thermal source, with a value of 97 kW for the system without Reheater (NRH), but this is reduced by 92.28% for the system with Reheater (RH). In addition, by optimizing the integrated cycle for a particle number of 25, the maximum thermal efficiency of 55.53% (NRH) was achieved, and 56.95% in the RH system. Likewise, for a particle number of 15 and 20 in the PSO algorithm, exergy destruction was minimized to 60.72 kW (NRH) and 112.06 kW (RH), respectively. Comparative analyses of some swarm intelligence optimization algorithms were conducted for the integrated S-CO2-SORC system, evaluating performance indicators, where the PSO optimization algorithm was favorable in the analyses, guaranteeing that it is the ideal algorithm to solve this case study.

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.

This article presents the modeling and simulation of a hybrid generation system, which uses solar energy generation, wind energy, and the regulation of a proton exchange membrane (PEM) cell to raise the demanded load, empowering the use of these hydride systems worldwide. This generation system was simulated for different locations in Puerto Bolivar (Colombia), Bremen (Germany), Beijing (China), and Texas (USA), for two demand profiles. The data used for the simulation was calculated using the mathematical solar model proposed by Beistow and Campbell for solar radiation. In contrast, for the wind resource evaluation, the Weibull probability distribution was used to calculate the most probable wind speed for each day, according to the historical data for each of the studied locations. Considering these data, the process transfer functions were used for tuning the control parameters for the hydrogen and oxygen production system. For the evaluation of the performance of these controllers, the indices of the absolute value of the error (IAE), the integral of the square of the error (ISE), the integral of the absolute value of the error for time (ITAE), and the integral of the square of the error for time (ITSE) were used. It was found that in the second load profile studied, better performance of the ITSE performance parameter was obtained, with stabilization times lower than those of the first profile.

Abstract This paper compares the performance of a group of intelligent algorithms such as the genetic algorithm (GA), particle swarm optimization (PSO), and repulsive particle swarm optimization (RPSO) based on the optimization of thermo-economic indicators such as the payback period (PBP), the levelized energy cost (LEC), the specific investment cost (SIC), and also in the optimization of the thermodynamic process (net power output) of an energy recovery system in a 2 MW natural gas internal combustion engine based on an organic Rankine cycle. Four parameters were considered to analyze and compare the performance of these algorithms: integral of squared error (ISE), integral of absolute error (IAE), integral of time-weighted absolute error (ITAE), and the integral of time-weighted squared error (ITSE). Analyses of variances (ANOVA) were proposed for each of the parameters studied. The PSO and RPSO algorithms presented the best performance in terms of the mean and the standard deviation of the ISE, IAE, ITAE, and ITSE parameters. Significant differences were not found between the three algorithms in terms of the parameters considered. However, significant differences did exist when comparing groups (pairs) of algorithms considering a significance level of 5%. The ANOVA analysis showed that ITAE was the most affected parameter by population size, while the IAE and ITSE parameters were the less affected. In the optimization, the PSO algorithm obtained the best performance in terms of convergence with values of 0.1110 USD/kWh (LCOE), 4.6971 years (PBP), 1114 USD/kWh (SIC), and 173.64 kW (Wnet). PSO-based algorithms obtained better performance in computational terms compared with the genetic algorithms.

This study evaluates the influence on the combustion process, fuel consumption, and polluting emissions in a diesel engine, which operates with biodiesel from soybean oil and water emulsions with percentages of 4% and 8%. For this study, a stationary diesel engine operating at four different torque conditions and a fixed rotation speed of 3400 rpm is used. Test fuels are diesel, soybean oil biodiesel, and SB4W and SB8W water emulsions. The results indicate that SB4W and SB8W cause a 6% reduction in calorific value and an 18% and 1% increase in viscosity and density. However, the presence of water in biodiesel can help reduce engine BSFC by 8%. The SB4W and SB8W allow a 23% reduction in NOx emissions. With the use of SB4W fuel, a reduction of 16%, 29%, and 14% in CO, HC, and smoke opacity is obtained compared to soybean oil biodiesel. The maximum inclusion of 8% water in soybean oil biodiesel is recommended since a higher percentage can cause the presence of incomplete combustions.

Abstract The excessive and irrational use of non-renewable energy is the consequence of the interaction of economic growth and environmental pollution. Therefore, it is increasingly necessary to propose energy and environmental improvements in the energy conversion systems according to sustainable development goals, especially in internal combustion engines. The exergetic analyses are a great tool because they allow identifying the components of greater irreversibilities. However, sustainable continuous improvement and opportunities can be found only by means of its advanced development. The study showed that in the waste heat recovery of a 2 MW gas engine based on the recuperative organic Rankine cycle (RORC) using R123 as working fluid, much of the exergy destroyed was endogenous 105.08 kW (81.6%). Steel, copper and aluminum were the proposed materials for the construction of the components, and through a life cycle analysis, it was found that the significant environmental impacts were found in the turbine for the aluminum with a value of 27617.21 kg of CO2 equivalent. Through the carbon footprint and advanced exergo-environmental analysis, it was found that the heat exchanger 1 is the equipment with the largest endogenous exergy destruction opportunities for improvement, also is the heat exchanger device with the most significant rate of environmental impacts, and the recommended material to use in the construction phase of the life-time of the system is the aluminum.