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©2020 Elsevier Ltd. All rights reserved. This document is the Published version of a Published Work that appeared in final form in Applied Energy. To access the final edited and published work see https://doi.org/10.1016/j.apenergy.2020.114753 The demand for biodiesel as an alternative and potentially renewable fuel is constantly rising. Biodiesel production from lipids in supercritical conditions offers several advantages over other catalytic processes. These advantages include high-efficiency production, environmental friendliness and the possibility of using a broad range of feedstock sources. As a consequence, there is a great interest in biodiesel production research using supercritical fluids as a sustainable technology option. In this sense, bibliometric reviews can be very useful for the interpretation of scientific production and research trends in this field. Thus, this work presents a scientometric study on biodiesel production research under supercritical conditions from 2001 to 2019, based on the Web of Science© database. 608 articles were analyzed and the parameters considered were: (i) publication type, language and output characteristics, (ii) Lotka's Law, Price's index and h-index, (iii) authors, countries and institutions collaboration analysis, (iv) publication performance by authors, journals, institutions and countries and (v) author keywords, single title words and keywords Plus analysis. The productivity patterns of authors, journals, institutions and authors keywords were found to fit Lotka's law. In terms of feedstock used in supercritical conditions, the bibliometric analysis showed a clear transition from first- to third-generation biodiesel, with special attention paid to the experimental study of supercritical reaction conditions. By contrast, further process optimization, the reduction of the severity of the supercritical conditions through devised strategies to lower energy consumption and further economic analysis are still needed, among other factors, for the real implementation of the technology.

Abstract The cement industry is one of the world’s largest energy consumers. In this work, a walk-through study of representative cement companies was carried out to characterize the energy profile of the cement industry in Colombia, with emphasis on evaluating the degree of obsolescence of the technology used in the processes, as well as identifying the main barriers that prevent the adaptation of more efficient technologies. Perception-surveys were performed among the energy managers to determine the barriers that hinder the implementation of energy efficiency measures. A factor that quantifies the influence of each type of barrier was defined according to the results of the survey. The results show that the Colombian cement industry has a specific energy consumption that is competitive with the largest cement producers in the world, while the technological obsolescence found is at a medium - low level. Furthermore, the main barrier to the penetration of energy efficiency technologies and measures is identified as the hidden costs associated with the implementation of these technologies. Finally, some conventional and emerging technologies are proposed to improve the efficiency of thermal energy use in the processes studied.

Les dimensions des coûts et des incitations nécessaires à l'intégration de la participation active de la demande dans le marché de gros de l'électricité sont soumises aux politiques énergétiques et à l'exploitation du système en vrac. L'industrie de l'électricité doit gagner en flexibilité opérationnelle pour soutenir la transition énergétique causée par les énergies renouvelables et la décarbonisation. Les services et technologies complémentaires des programmes de réponse à la demande peuvent être optimisés en exploitant la variété des utilisations de cette ressource. L'objectif principal de ce travail est d'appliquer le concept d'élasticité de substitution dans un programme de déplacement stratégique de la demande pour promouvoir l'intégration des énergies renouvelables et la réduction de l'énergie non desservie, en considérant une répartition de la production économique et sûre. La méthodologie est analysée à travers une étude de cas appliquée sur le marché de l'électricité de la République dominicaine, dans laquelle l'élasticité des coefficients de substitution est utilisée pour ajuster les variations inférieures à 10,49% de la demande de base en période de pointe. Ces variations réduisent le coût d'exploitation de la production de 8,4 %, le coût marginal de 30,19 % et l'énergie non desservie de 19,1 % lorsque l'énergie renouvelable augmente de 5 %. L'inclusion du coût des émissions de CO 2 dans la simulation de la fonction de coût d'exploitation rend la fonction objectif supérieure à la fonction de base. Pour des variations relatives du coût d'exploitation allant de 7,27% à 16,03%, la réduction en tonnes d'équivalent CO 2 varie de 2,77 à 28,02. Cette étude contextualise l'effet économique du contrôle des émissions de CO 2, offrant de nouvelles possibilités pour optimiser le fonctionnement du système et le marché de gros de l'électricité sur la base de programmes de réponse à la demande qui encouragent une consommation flexible, avec des résultats économiques et environnementaux favorables. Las dimensiones de los costos e incentivos necesarios para integrar la respuesta de la demanda en el mercado mayorista de electricidad están sujetas a las políticas energéticas y a la operación del sistema a granel. La industria eléctrica debe ganar flexibilidad operativa para apoyar la transición energética causada por las energías renovables y la descarbonización. Los servicios complementarios y las tecnologías de los programas de respuesta a la demanda se pueden optimizar explotando la variedad de usos de este recurso. El objetivo principal de este trabajo es aplicar el concepto de elasticidad de sustitución en un programa estratégico de cambio de demanda para promover la integración de energías renovables y la reducción de la potencia no servida, considerando un despacho de generación económico y seguro. La metodología se analiza a través de un estudio de caso aplicado en el mercado eléctrico de la República Dominicana, en el que se utiliza la elasticidad de los coeficientes de sustitución para ajustar las variaciones por debajo del 10,49% de la demanda base en el período pico. Estas variaciones reducen el coste operativo de generación en un 8,4%, el coste marginal en un 30,19% y la energía no servida en un 19,1% cuando la energía renovable aumenta en un 5%. La inclusión del coste de las emisiones de CO 2 en la simulación de la función de coste operativo hace que la función objetivo sea superior a la función de referencia. Para variaciones relativas en el costo de operación que van del 7.27% al 16.03%, la reducción en toneladas de CO 2 equivalente varía de 2.77 a 28.02. Este estudio contextualiza el efecto económico del control de emisiones de CO 2, dando nuevas posibilidades para optimizar la operación del sistema y el mercado eléctrico mayorista a partir de programas de respuesta a la demanda que incentiven el consumo flexible, con resultados económicos y ambientales favorables. The dimensions of the costs and incentives necessary for integrating demand response into the wholesale electricity market are subject to energy policies and bulk system operation. The electricity industry must gain operational flexibility to support the energy transition caused by renewable energy and decarbonization. Complementary services and technologies of demand response programs can be optimized by exploiting the variety of uses of this resource. The main objective of this work is to apply the concept of elasticity of substitution in a strategic demand shift program to promote the integration of renewable energies and the reduction of non-served power, considering an economical and safe generation dispatch. The methodology is analyzed through a case study applied in the Dominican Republic's electricity market, in which the elasticity of substitution coefficients is used to adjust variations below 10.49% of the base demand in the peak period. These variations reduce the generation operating cost by 8.4%, marginal cost by 30.19%, and non-served power by 19.1% when renewable energy increases by 5%. The inclusion of the cost of CO 2 emissions in the simulation of the operating cost function makes the objective function higher than the baseline function. For relative variations in operating cost ranging from 7.27% to 16.03%, the reduction in tons of CO 2 equivalent varies from 2.77 to 28.02. This study contextualizes the economic effect of the CO 2 emissions control, giving new possibilities to optimize system operation and the wholesale electricity market based on demand response programs that encourage flexible consumption, with favorable economic and environmental results. تخضع أبعاد التكاليف والحوافز اللازمة لدمج استجابة الطلب في سوق الكهرباء بالجملة لسياسات الطاقة وتشغيل النظام بالجملة. يجب أن تكتسب صناعة الكهرباء مرونة تشغيلية لدعم انتقال الطاقة الناجم عن الطاقة المتجددة وإزالة الكربون. يمكن تحسين الخدمات التكميلية وتقنيات برامج الاستجابة للطلب من خلال استغلال مجموعة متنوعة من استخدامات هذا المورد. الهدف الرئيسي من هذا العمل هو تطبيق مفهوم مرونة الاستبدال في برنامج تحويل الطلب الاستراتيجي لتعزيز تكامل الطاقات المتجددة وتقليل الطاقة غير المخدومة، مع مراعاة إرسال توليد اقتصادي وآمن. يتم تحليل المنهجية من خلال دراسة حالة مطبقة في سوق الكهرباء في جمهورية الدومينيكان، حيث يتم استخدام مرونة معاملات الاستبدال لتعديل الاختلافات دون 10.49 ٪ من الطلب الأساسي في فترة الذروة. تقلل هذه الاختلافات من تكلفة تشغيل التوليد بنسبة 8.4 ٪، والتكلفة الحدية بنسبة 30.19 ٪، والطاقة غير المخدومة بنسبة 19.1 ٪ عندما تزيد الطاقة المتجددة بنسبة 5 ٪. إن إدراج تكلفة انبعاثات ثاني أكسيد الكربون في محاكاة وظيفة تكلفة التشغيل يجعل وظيفة الهدف أعلى من وظيفة خط الأساس. بالنسبة للتغيرات النسبية في تكلفة التشغيل التي تتراوح من 7.27 ٪ إلى 16.03 ٪، يتراوح الانخفاض في أطنان مكافئ ثاني أكسيد الكربون من 2.77 إلى 28.02. تضع هذه الدراسة في سياق التأثير الاقتصادي للتحكم في انبعاثات ثاني أكسيد الكربون، مما يتيح إمكانيات جديدة لتحسين تشغيل النظام وسوق الكهرباء بالجملة بناءً على برامج الاستجابة للطلب التي تشجع الاستهلاك المرن، مع نتائج اقتصادية وبيئية مواتية.

In Colombia en paz Oil Field, the opportunity to increase productivity through the implementation of secondary recovery methods is visualized. The project aims at basal sands because the quality of its fluid is better compared to the upper sands (30 ° API vs 20 ° API, respectively). The main objective is to evaluate the effect of gas reinjection on oil production. Today, the field has a gas lift network (Gas Lift) with an available pressure of 1,200 psi. Which would be used for the implementation of the process both cyclic and continuous and with flow rates between 100 - 1,000 kscfpd (kilo standard cubic feet per day). Oil production is expected to increase due to pressurization in the well drainage area and increased mobility by partial solubility of the gas in the crude. At the Center of Innovation and Technology - Instituto Colombiano del Petróleo, the recovery of crude oil was measured by the injection of production gas. The technical standard GTN-I-009 was used to conduct runs with production gas. The tests were performed at 138 ° F reservoir temperature, 440 scf / STB Gas Oil Ratio and crude with Basic Sediments and Water (BS&W) less than 1% as required by the experimental protocols. At the laboratory, the total recovered crude with production gas was 18 % at the maximum operating pressure of 1,600 psi for the Gas Lift system. The Minimum Miscibility Pressure was estimated at 8,407 psi by linear extrapolation using experimental data taken from Slim Tube Equipment

This paper presents the state of the art regarding electrical equipment's immunity to voltage sags. It deals with immunity analysis and voltage sag generators. An alternative methodology for testing equipment regarding voltage sag is proposed, along with immunity assessment. A comprehensive bibliographic review was made, describing voltage sag immunity standards and selected research and industry publications. The proposed methodology for assessing immunity was based on the literature presented and the authors' work.

Abstract Active configuration i.e., source coupling via a power converter, is the most common configuration for fuel cell/supercapacitor (FC/SC) vehicles. Passive connection of the FC with the SCs without any converters is an original and less expensive solution to distribute the power among the sources. This passive configuration does not require an energy management strategy. In fact, the power distribution only depends on the FC and SC impedance characteristics. Conventional methods to size the SC follow two criteria: storage capacity and maximum voltage. In this paper, a third criterion is added which is the FC operating current dynamics. This novel sizing methodology reduces the FC degradation and improves the global system efficiency. Experimental results provide validation to the proposed sizing approach. The SCs boost the FC to meet the requirements of the load with a guarantee of system stability reaching higher global performances and less stress to the FC.

Abstract The present paper reports the construction of an experimental installation to measure local condensing two-phase flow heat transfer coefficient and frictional pressure drop within mini-channel tubes, the validation measurements developed with R134a and the experimental measurements of heat transfer coefficient and frictional pressure drop made with R32 and R410A. This experimental work is carried out in a test apparatus which allows determining the local heat flux extracted from the condensing fluid. For this purpose, the wall temperature is measured along the test section in several points. The saturation temperature is determined from the saturation pressure, which is measured at the inlet and the outlet of the test channel. Experimental data of R32 and R410A are also compared with some predicting models widely accepted in the literature.