نشریه انرژی ایران
سال بیست و چهارم شماره 1 (پیاپی 90، بهار 1400)

Increasing growth in demand for natural gas and its dispersal in the world will causes to the growing dependence of countries with natural gas consumption on international natural gas trade, thus increasing competition among natural gas exporters in terms of volume and scope. therefore, a complex network of trade relations between countries has been created and the interactions between them have been developed. The aim of this study is to analyze the position of countries in the international natural gas trade network by using graph theory. In this research, the international natural gas trade network in 2018 has been examined separately by two HS codes. The distinguishing feature of this article is that all countries are included in the international natural gas trade network. Analysis of the network based on various indicators shows that although Iran is the second largest holder of natural gas resources in the world and has a special position in the transit of natural gas, but is not an important player in the international trade network of natural gas. In addition, according to the Closeness Centrality Index, Singapore, the United Kingdom and Italy have the highest Closeness Centrality Index, and as a result, have been more successful in establishing trade relations with other countries in the network. Also, countries like Norway and Russia as the largest exporters of natural gas, have less Closeness.  Therefore, other criteria, such as having diverse trade relationships, are decisive in the natural gas trade network. The results also show that in the liquid natural gas trade network, the network density is relatively higher than the network density through the pipeline because the pipeline infrastructure is located under geographic constraints, diplomatic relations and political factors while natural gas trade has a relatively more flexibility. With the increasing demand and supply resources in international natural gas trade supply in the future, liquefied natural gas is likely to become the most important form of natural gas trade.

In this research, the trigeneration cycle including regenerative Organic Rankine Cycle, liquified natural gas cold energy, and absorption refrigeration system is simulated by applying condenser boiler hot water from the perspective of energy and exergy-economy. In the proposed cycle, medium temperature water leaving the condensing boiler is used as the heat sources of ORC, LNG cold energy, and absorption refrigeration cycle and then returns to the boiler. The effects of various parameters such as boiler outlet temperature, condenser temperature, generator temperature, evaporator temperature as well LNG turbine pressure on the energy and exergy efficiencies, COP, exergy destruction rate, and total cost rate of the system is investigated. The results indicated that increasing boiler outlet temperature leads to the increase of exergy destruction rate while the decrease of energy and exergy efficiencies. First and second law efficiencies will increase as the condenser temperature, generator and evaporator temperatures, and LNG turbine pressure increase. From economic analysis, it was found that by increasing boiler temperature, the overall system cost rate increases. LNG heat exchanger, ORC condenser, and boiler are components that should be considered as they have the highest exergy destruction.

Currently, high-rise buildings construction is expanding while certain climatic considerations are not foreseen in the design and implementation and design decisions are often made similar to midrise and low-rise buildings, and one of the most important reasons is the lack of relevant specialized research in the country. The purpose of this study is to explain the climatic frameworks in order to select the optimal models in the design of high-rise buildings with the approach of reducing energy consumption in order to develop climate design criteria. In this regard, the present study by means of descriptive analytical method with a quantitative approach compares seven main indicators affecting the reduction of energy consumption including building form, opening form and its area ratio, rotation angle, canopy depth, type, and thickness of thermal insulation and exterior wall glass in different conditions by using energy simulator software to find the optimal mode in terms of energy saving. The results of data analysis show that the ratio of opening areas, glass material and canopy depth are the most influential indicators and building form, for building rotation, form and dimensions of openings are the least effective on research objectives. Also, rectangular buildings with east-west elongation and horizontal windows with horizontal awnings to a depth of 100 cm on the south and east sides and vertical awnings to a depth of 150 cm on the north and west sides have a good performance in the study climate and have minimal energy consumption.

The use of office equipment for various office tasks is increasing day by day due to the advancement of technology. Purchase of low-consumption equipment and the proper operation causes to reduce the energy consumption of the electrical system and the cost of electricity bill of the office building. For this reason, in this article, the optimal selection of conventional office equipment is investigated to improve the technical and economic indices. The consumption rate, speed, and installation and operation costs of equipment are samples of technical and economic indices of devices that are considered using the life cycle cost method for selecting the optimal technology of office equipment. Finally, the optimal technology of devices is selected using the numerical simulation in MATLAB software. The three operational periods, 1, 10, and 20 years starting from 1400, are considered the researchchr(chr(chr('39')39chr('39'))39chr(chr('39')39chr('39')))s operational period. Moreover, the methods for more improvement of technical and economic indices of the office building are also proposed and evaluated after selecting the best technology of equipment. Results show a considerable improvement in the efficiency of the electrical system of the office building. In different devices, electricity consumption and costs are reduced by about 20-70 percent by selecting the proper technology using the proposed method.

PCMs are materials with thermal storage capability which are used with two purposed in buildings: Increase the thermal interia of the building to greater use of the natural heat of the sun to heat and also reduce the need for heating and cooling by cooling-heating equipment. In this study the use of a pcm layer in the ceiling and walls of a building is simulated using the c++ software in a hot and humid climate (Boushehr) and cold and dry climate (Hamedan) to energy consumption and maintain indoor temperature close to comfortable temperature. The effects of PCM layer on reduce input/loss heat in summer and winter and the internal tempreture of the ceiling and walls were evaluted in all months of the year. Also, to explore the best orientation for the wall includes PCM, different orientation of the wall is simulated. The results showed that the phase change temperature of PCM should be in the range work of desired climate. Hence, PCM that used for a climate will not be suitable for another the use of a 3cm layer of PCM with the phase change temperature of 280C can reduce the input/loss heat through the roof of the building to 61% in summer and 12% in winter in Boushehr city. Also, by increasing the thickness of the PCM, it’s performance improvements in this area. The results of the simulation showed that the PCM in the wall facing south show best performance.

Sustainable energy generation, transmission, consumption, and storage is one of the most important concerns in modern world, which includes technical, economic, political, social and environmental aspects. The right approach to solve this challenging and multifaceted problem requires interdisciplinary fashions to power and energy systems that bridge the gap between all the stakeholders (i.e., researchers, engineers, politicians, citizens, industry owners, and others). In such interdisciplinary study, the new Energy Informatics field plays an important role in which various disciplines generally address the techno-economic challenges of energy and power systems throughout the whole chain from production to consumption and sale/purchase. The purpose of this article is to draw an overview and, of course, an accurate view of the field of Energy Informatics by addressing the educational/research opportunities/challenges and considering the current consequences and future directions of industrial innovations related to this innovative field. This study, beyond purely scientific perspectives and by including reflections with applied and industrial approaches, facilitates data analysis to realize education and research policy for this modern area. Initially, recommendations for the content of the Energy Informatics introductory course were drawn up and discussed to educate the new generation of professionals who must meet the interdisciplinary challenges of new and integrated energy systems of the future. Then, a preliminary proposal is made for the establishment of the National Energy Informatics Institute, in which the necessity and structure of such a center is discussed in order to have a precise policy making; preparing to enter the future world of energy.

One of the main parts of energy consumption and greenhouse gasses emission is the building sector. Furthermore, energy auditing is considered as one of the efficient approaches to detect efficiency and energy saving. In 2020, the energy consumption index for Islamic Azad University of Ardabil was equivalent to which has contributed to 4623 tons of greenhouse gasses emission over the year, a sign of inappropriate circumstances for energy consumption. Since natural gas constitutes 91% of the total energy consumption in this section, more investment is essential to reduce the consumption index. In this paper, evaluating the proposed and implemented proceedings is the purpose. A smart design of the powerhouse and utilizing a solar water heater are some of the recommendations for improving energy consumption. Light intensity measuring, contractual demand reduction, capacitor bank panel modification, thermal imaging of the electrical and mechanical plants, and economic evaluation of each of them could result in saving, energy consumption index reduction, and pollution emission.