• Energy Research

Mini solar flat plate collectors have gained traction due to their cost-effectiveness, high efficiency in converting solar radiation to heat energy, and versatility in residential and commercial applications, offering long lifespans with minimal maintenance. Optimizing the thermal performance of solar flat plate collectors using numerical simulations helps enhance their efficiency, making them even more appealing for small-scale heating and hot water applications. This study investigates the flow behavior and temperature distribution of air within a small-sized solar collector (286 × 800 × 70 mm) and optimizes its design for achieving the highest outlet air temperature. The optimization process included varying geometric parameters, such as the wavy structure hole diameter, and considering a range of operating conditions, including ambient conditions and solar intensities. This analysis aimed to understand the flow behavior and temperature distributions within the solar collector. The numerical studies provided valuable insights into the thermal and flow characteristics of the collector. The velocity distribution of the fluid within the collector aided in understanding the flow behavior, optimizing the flow path to minimize pressure drop, and maximizing heat transfer. Additionally, calculations were performed to determine total useful heat, outlet temperatures, and efficiencies. The study also discusses the optimal design and operating conditions for the collector.

This study examined an Organic Rankine Cycle powered by a parabolic trough collector and a two-tank thermal storage system based on the development of a mathematical model, for the conditions of the city of Itajubá in Brazil. First, geometrical optics and heat transfer models of the collector–receiver set were used to determine the thermal equilibrium of the solar thermal collector system and parameters such as the efficiency of the solar field, heat and optical losses, and thermal energy of the outlet fluid. Next, the thermal equilibrium of the Organic Rankine Cycle was found in order to establish its operational parameters. Finally, the behavior of the thermal storage system was analyzed through its modeling. Once the characterization of the storage system was completed, the integrated operation of the proposed system was evaluated. Given Itajubá’s weather conditions, the results indicate that an electricity generation system can be implemented with the Solel UVAC Cermet selective coating for the absorber tube, water as the heat transfer fluid, and R-245fa as the working fluid. Based on the solar irradiation profile (1 March 2019), the parabolic trough collectors provided 63.3% of the energy required by the Organic Rankine Cycle to generate 7.4 kW, while the thermal storage system provided 36.4% of the energy demanded by the power generation block. Additionally, the results demonstrate the main conclusions that the turbine’s efficiency was influenced by parameters such as rotational speed, which is affected by the turbine inlet temperature, which, in turn, depends on the behavior of the solar irradiation profile onsite.

One way to increase overall natural gas engine efficiency is to transform exhaust waste heat into useful energy by means of a bottoming cycle. Organic Rankine cycle (ORC) is a promising technology to convert medium and low grade waste heat into mechanical power and electricity. This paper presents an energy and exergy analysis of three ORC-Waste heat recovery configurations by using an intermediate thermal oil circuit: Simple ORC (SORC), ORC with Recuperator (RORC) and ORC with Double Pressure (DORC), and Cyclohexane, Toluene and Acetone have been proposed as working fluids. An energy and exergy thermodynamic model is proposed to evaluate each configuration performance, while available exhaust thermal energy variation under different engine loads was determined through an experimentally validated mathematical model. Additionally, the effect of evaportating pressure on net power output , absolute thermal efficiency increase, absolute specific fuel consumption decrease, overall energy conversion efficiency, and component exergy destruction is also investigated. Results evidence an improvement in operational performance for heat recovery through RORC with Toluene at an evaporation pressure of 3.4 MPa, achieving 146.25 kW of net power output, 11.58% of overall conversion efficiency, 28.4% of ORC thermal efficiency, and an specific fuel consumption reduction of 7.67% at a 1482 rpm engine speed, a 120.2 L/min natural gas Flow, 1.784 lambda, and 1758.77 kW mechanical engine power.

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.  

Dans le secteur industriel du raffinage et de la pétrochimie, de grandes quantités d'énergie sont utilisées, donc l'utilisation du concept d'exergie permet une utilisation rationnelle de cette ressource. Dans les différentes études d'exergie et d'exgoéconomie appliquées dans les usines pétrochimiques, des paramètres d'intérêt ont été déterminés pour évaluer l'efficacité thermique, le potentiel d'amélioration des procédés, les irréversibilités produites par l'interaction entre les composants du système et le fonctionnement de chacun, et les coûts énergétiques associés à chacune de ces irréversibilités. Cet article présente une analyse exergétique avancée et une analyse exergétique-économique appliquée à une usine de production d'acide nitrique d'une capacité installée de 350 tonnes métriques par jour, dont le principe de fonctionnement est basé sur la méthode d'Ostwald, et à la fois le comportement de destruction exergétique endogène et le comportement de destruction exergétique exogène, évitable et inévitable sont étudiés, la destruction exogène exogène, évitable et inévitable et les coûts exergétiques associés dans chacun des équipements de transfert de chaleur et des équipements réactifs qui composent l'usine, autour de la température de refroidissement dans les étapes intermédiaires du train de compression sont étudiés à l'aide d'un modèle mathématique. Les réactions chimiques impliquées dans le processus de production sont les points d'intérêt dans la recherche de ce travail. Certains des résultats montrent que 54 % de la destruction totale de l'exergie peut être récupérée en intervenant dans les composants. D'autre part, dans le convertisseur catalytique (CONV), il est pratique de considérer les coûts d'investissement pour réduire les coûts de destruction de l'exergie. De même, dans le réchauffeur de gaz de queue (TGH), il est avantageux de réduire l'investissement total pour améliorer l'économie du processus. En revanche, le coût de la destruction exergétique de l'usine s'est traduit par 770,77 USD/h. En outre, il a pu être déterminé que les interactions entre les composants affectent de manière significative les coûts d'investissement. En el sector industrial refino y petroquímico se utilizan grandes cantidades de energía, por lo que utilizar el concepto de exergía permite un uso racional de este recurso. En los diferentes estudios de exergía y exergoeconomía aplicados en plantas petroquímicas, se han determinado parámetros de interés para evaluar la eficiencia térmica, el potencial de mejora de procesos, las irreversibilidades producidas por la interacción entre los componentes del sistema y el funcionamiento de cada uno, y los costes energéticos asociados a cada una de estas irreversibilidades. En este trabajo se presenta un análisis de exergía avanzado y un análisis de exergía-económico aplicado a una planta de producción de ácido nítrico con una capacidad instalada de 350 toneladas métricas por día, cuyo principio de funcionamiento se basa en el método de Ostwald, y se estudian tanto el comportamiento de la destrucción de exergía endógena como el comportamiento de la destrucción de exergía exógena, evitable e inevitable, la destrucción de exergía exógena, evitable e inevitable y los costos de exergía asociados en cada uno de los equipos de transferencia de calor y equipos reactivos que componen la planta, sobre la temperatura de enfriamiento en las etapas intermedias del tren de compresión se estudian utilizando un modelo matemático. Las reacciones químicas que intervienen en el proceso productivo son los puntos de interés en la investigación de este trabajo. Algunos de los resultados muestran que el 54% de la destrucción total de exergía se puede recuperar interviniendo en los componentes. Por otro lado, en el Convertidor Catalítico (CONV), es conveniente considerar los costes de inversión para reducir los costes de destrucción de exergía. Del mismo modo, en el calentador de gas de cola (TGH), es beneficioso reducir la inversión total para mejorar la economía del proceso. Por otro lado, el coste de destrucción exergética de la planta resultó en 770,77 USD/h. Además, se podría determinar que las interacciones entre los componentes afectan significativamente a los costes de inversión. In the refining and petrochemical industrial sector, large amounts of energy are used, so using the concept of exergy allows a rational use of this resource. In the different exergy and exergoeconomics studies applied in petrochemical plants, parameters of interest have been determined to evaluate the thermal efficiency, the potential for process improvement, the irreversibilities produced by the interaction between the components of the system and the operation of each one, and the energy costs associated with each of these irreversibilities. This paper presents an advanced exergy analysis and an exergy-economic analysis applied to a nitric acid production plant with an installed capacity of 350 metric tons per day, whose operating principle is based on the Ostwald method, and both the behavior of endogenous exergy destruction and the behavior of exogenous, avoidable and unavoidable exergy destruction are studied, exogenous, avoidable and unavoidable exergy destruction and the associated exergy costs in each of the heat transfer equipment and reactive equipment that make up the plant, about the cooling temperature in the intermediate stages of the compression train are studied using a mathematical model. The chemical reactions involved in the production process are the points of interest in the research of this work. Some of the results show that 54 % of the total exergy destruction can be recovered by intervening in the components. On the other hand, in the Catalytic Converter (CONV), it is convenient to consider the investment costs to reduce the exergy destruction costs. Similarly, in the Tail Gas Heater (TGH), it is beneficial to reduce the total investment to improve the process economics. On the other hand, the cost of exergy destruction of the plant resulted in 770.77 USD/h. In addition, it could be determined that the interactions between the components significantly affect the investment costs. في قطاع التكرير والصناعات البتروكيماوية، يتم استخدام كميات كبيرة من الطاقة، لذلك فإن استخدام مفهوم الطاقة الخارجية يسمح بالاستخدام الرشيد لهذا المورد. في دراسات الطاقة الخارجية والاقتصاد الخارجي المختلفة المطبقة في مصانع البتروكيماويات، تم تحديد المعلمات ذات الأهمية لتقييم الكفاءة الحرارية، وإمكانية تحسين العملية، واللارجعات الناتجة عن التفاعل بين مكونات النظام وتشغيل كل منها، وتكاليف الطاقة المرتبطة بكل من هذه اللارجعات. تقدم هذه الورقة تحليلًا متقدمًا للطاقة الخارجية وتحليلًا اقتصاديًا للطاقة الخارجية يطبق على مصنع لإنتاج حمض النيتريك بسعة مركبة تبلغ 350 طنًا متريًا يوميًا، يعتمد مبدأ تشغيله على طريقة أوستوالد، ويتم دراسة كل من سلوك تدمير الطاقة الخارجية الذاتية وسلوك تدمير الطاقة الخارجية الخارجية التي يمكن تجنبها والتي لا يمكن تجنبها، وتدمير الطاقة الخارجية الخارجية التي يمكن تجنبها والتي لا يمكن تجنبها وتكاليف الطاقة الخارجية المرتبطة بها في كل من معدات نقل الحرارة والمعدات التفاعلية التي تشكل المصنع، حول درجة حرارة التبريد في المراحل الوسيطة من قطار الضغط يتم دراستها باستخدام نموذج رياضي. التفاعلات الكيميائية التي تنطوي عليها عملية الإنتاج هي نقاط الاهتمام في البحث في هذا العمل. تظهر بعض النتائج أنه يمكن استرداد 54 ٪ من إجمالي تدمير الطاقة الخارجية عن طريق التدخل في المكونات. من ناحية أخرى، في المحول الحفاز (CONV)، من المناسب النظر في تكاليف الاستثمار لتقليل تكاليف تدمير الطاقة الخارجية. وبالمثل، في سخان الغاز الذيلي (TGH)، من المفيد تقليل إجمالي الاستثمار لتحسين اقتصاديات العملية. من ناحية أخرى، أسفرت تكلفة تدمير الطاقة الخارجية للمحطة عن 770.77 دولار أمريكي/ساعة. بالإضافة إلى ذلك، يمكن تحديد أن التفاعلات بين المكونات تؤثر بشكل كبير على تكاليف الاستثمار.

Given the increase in population and energy demand worldwide, alternative methods have been adopted for the production of hydrogen as a clean energy source. This energy offers an alternative energy source due to its high energy content, and without emissions to the environment. In this bibliometric analysis of energy production using electrolysis and taking into account the different forms of energy production. In this analysis, it was possible to evaluate the research trends based on the literature in the Scopus database during the years 2011–2021. The results showed a growing interest in hydrogen production from electrolysis and other mechanisms, with China being the country with the highest number of publications and the United States TOP in citations. The trend shows that during the first four years of this study (2011–2014), the average number of publications was 74 articles per year, from 2015 to 2021 where the growth is an average of 209 articles, the journal that published the most on this topic is Applied Energy, followed by Energy, contributing with almost 33% in the research area. Lastly, the keyword analysis identified six important research points for future discussions, which we have termed clusters. The study concludes that new perspectives on clean hydrogen energy generation, environmental impacts, and social acceptance could contribute to the positive evolution of the hydrogen energy industry.