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Energy Management and Technology - Volume:7 Issue: 1, Winter 2023

Journal of Energy Management and Technology
Volume:7 Issue: 1, Winter 2023

  • تاریخ انتشار: 1401/09/15
  • تعداد عناوین: 7
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  • Seyyed Kazem Yekani, Ebrahim Abdi Aghdam *, Mehrdad Sarabi Pages 1-10
    The dependence of human beings on motor vehicles in their everyday life and the decrease of oil reserves all over the world have doubled the importance of attention to Spark Ignition (SI) engines. One of the most efficient ways to reduce fuel cost and knock intensity in SI engines is to use gasoline-Natural Gas (NG) dual fuel mixture. In the current study, 4 different combinations of gasoline and NG (with gasoline as the predominant fuel), namely G100 (100% gasoline), G87.5 (87.5% gasoline and the rest NG), G75 (75% gasoline and the rest NG), and G62.5 (62.5% gasoline and the rest NG) were investigated under stoichiometric conditions at the engine speed of 1800 rpm and the compression ratio of 10. The safe knocking limit was defined as the range with the knocking cycle percentage of lower than 5%. Then using the data obtained from the in-cylinder pressure of 400 consecutive cycles, the optimum spark advance was determined for each of the fuel modes. It was observed that the optimum spark advance based on indicated mean effective pressure (imep) fell in the non-knocking limit in all of the dual fuel modes. The analysis of the results indicated that as the fraction of NG in the dual fuel mixture increased, standard deviation (σ) and coefficient of variation (COV) of imep decreased. As for fuel economy, the results revealed that with the increase of NG fraction in the dual fuel mixture, the amount of the work generated per unit price increased significantly.
    Keywords: Dual fuel, SI engine, Safe knock limit, Gasoline, Natural gas
  • Hasan Bargozin *, Taher Yousefi Amiri, Sina Hosseini Pages 11-18
    Excessive consumption of energy and the production of various pollutants in the last century has caused global warming. Also, due to the increase in fossil fuel prices in recent decades and non-renewable sources, the country's annual energy consumption has become a fundamental challenge for developing countries. In Iran, energy consumption in various sectors is several times higher than global consumption, and the -building sector has the highest energy consumption. In the building sector, despite the emphasis on insulation, traditional insulation is rarely used due to its problems. A new generation of water-based paints containing silica aerogels is thermal insulators that can be used in various parts of the buildings. These insulation paints with their unique properties are a good option for insulating buildings and preventing excessive energy loss. This research investigates the effect of these paints on energy loss at different thicknesses and environmental conditions.
    Keywords: Building, energy loss, Liquid insulation, Silica Aerogel, Simulation
  • Setare Peirow, Fatemeh Razi Astaraei *, AmirAli Saifoddin Asl, Hossein Yousefi Pages 19-26

    Hospitals are among large-scale buildings with complicated energy system. Due to the significance of the hospital’s energy system in treating patients and general health, monitoring its resiliency is a crucial issue. Unfortunately, most of recent hospitals have been designed and developed, disregarding the importance of energy system’s resiliency. In this study, the resiliency of a hospital’s energy system has been investigated by quantifying the related criteria extracted from Hospitals’ Standard books and determining the system’s resiliency score. First, a hospital located in Tehran, Iran, has been selected as the case study, and its complicated energy system was modeled with Design-Builder software. Results of the simulation showed that the annual energy consumption of the current system was 3.08 GWh of electricity and 4.23 GWh of gas. Then, the energy system was separated into tiny wards, and the resiliency of each ward was measured using criteria linked to the resiliency of medical facilities by the scoring method. Calculating the weighted mean of the various wards yields the system’s overall resiliency. The mean resiliency score of the case study was calculated to be 4.13 (range from 1 to 5), which is considered a good value. However, the hospital’s power supply system which contributes the most to the total resiliency grade, owed the lowest score. Consequently, boosting the performance of this system may lead to a major influence on promoting the total energy system's resiliency.

    Keywords: Hospital' s energy system, Design-builder, resiliency, scoring method, Resilience criteria
  • Abuzar Abazari *, MohammadMahdi Aziminia Pages 27-33

    A surge oscillating flap-type device is one of the most usable wave energy converters for extracting power from ocean waves. The relative movement of the piston and cylinder of a hydraulic power take-off system attached to the vertical flap and the base is responsible for converting the mechanical oscillations of the flap into hydraulic pressure in a bottom-hinged flap-type converter. This study proposes a new design to investigate its hydrodynamic characteristics and output power, including a vertical buoyant flap hinged to a horizontal gravity flap. This analysis is done by solving the governing Laplace equation through the BEM approach in ANSYS AQWA. The steady-state relative displacement between flaps is obtained through a time-domain analysis, which is used to calculate the output power. The results show that the proposed floating design can extract power from ocean waves at offshore sites. The WEC is designed to match its power resonance periods with the most wave dominant periods of 8-10 s.

    Keywords: bottom hinge converter, floating WEC, surge oscillating flap-type converter, time-domain analysis, Regular wave
  • Farkhondeh Jabari *, Morteza Nazari-Heris, Mehdi Abapour Pages 34-42
    Nowadays, large power systems are facing new challenges gifted from emerging and renewable energy resources. This is even worse in developing countries where load is growing rapidly and power systems are relatively weak. With more complex power systems occurrence of a contingency such as unexpected demand during extremely-hot summer days or transient heat waves may lead to voltage drops, cascaded trips and catastrophic wide area blackouts. A few solutions have been proposed, amongst which demand response is known as an effective tool. Demand response programs (DRPs) are implemented on residential, commercial and industrial loads to economically optimize energy systems, improve overall efficiency and reliability, and enhance their stability margins. This paper presents three demand-side management strategies implemented on Iran’s commercial and industrial sectors. Operational reserve programs, incentive-based reduction or disruption of electricity demand during on-peak time intervals, and replacement of traditional lamps with energy efficient ones are applied as three strategic DRPs on industrial and commercial sectors. Three cost-effective solutions are provided for participation of industrial customers in summer peak clipping programs: (a) Transferring the weekend from Friday to one of midweek days, (b) Transferring a part of each co-operated consumer from on-peak demand hours with high electricity tariffs to off-peak time intervals with lower energy prices, (c) DSM by annual overhaul and work suspension. In case of 100 kW power consumption at medium-peak load hours, commercial customer mustat least reduce 10% of this amount at on-peak demand time interval. Economic and environmental benefits obtained from numerical studies are comprehensively provided. It is found that the total asynchronous demand reduction after participation of 287 commercial centers in demand side management programs is equal to 10.187 MW. Total industrial load reduced after implementation of disruption strategy at annual on-peak day (July 20) is equal to 743 MW.
    Keywords: Demand response programs, commercial, industrial sectors, operational reserve, annual overhaul, work suspension
  • Ahmad Hajinezhad, Hossein Yousefi *, Rahim Moltames, Reza Fattahi, Amirhossein Fathi Pages 43-48
    In this paper, a Rankin cycle-based heat and power generation system is simulated. The input energy of the system is supplied by the combustion of natural gas in the boiler. Condenser heat recovery is used to supply thermal energy and on the other hand, the power generated by the turbine is used to supply electricity demand. The first and second laws of thermodynamics and the law of conservation of mass are used to analyze the energy and exergy performance of the system. Finally, the effect of changing each of the performance parameters on the energy and CO2 emission of the system is investigated. According to the results, the turbine output power, net power production, electrical efficiency, energy efficiency, exergy efficiency, and CO2 production is obtained as 354.63 kW, 353.53 kW, 24.23%, 94.92%, 74.38%, and 81.1 g/s, respectively. Furthermore, the simulation results show that increasing the turbine inlet temperature increases electrical efficiency and exergy. Increasing the condenser outlet temperature also reduces electrical and exergy efficiency. On the other hand, increasing natural gas consumption only increases CO2 production and does not affect electrical, energy, and exergy efficiencies.
    Keywords: Cogeneration system, Rankine cycle, Energy, Exergy Analysis, Environment
  • Farhood Ghalkhani, Mohsen Hayati *, Hamdi Abdi Pages 49-58
    Increasing the energy consumption, greenhouse gas emission, the need to improve reliability and sustainable supply of electricity, are some of the most challenging issues in modern power systems. To tackle these challenges, using renewable-energy based sources to reduce dependence on fuel-based energy sources is focused. For this purpose, using the electric vehicles, in the form of distributed generation, as an appropriate solution to replace combustion vehicles is strongly considered. In this paper, the energy management in multi-agent microgrids in an integrated framework including the electric vehicle charging stations and reducing pollution is suggested. In the proposed strategy, to manage the energy optimally, two stages are implemented. First, in each microgrid, local energy management is performed, pollution of diesel generation sources is considered, and the hourly amounts of surplus/shortage powers are determined. At the second stage, the microgrid is connected to the upstream network, and the impacts of electric vehicle charging stations, and also the sale/buy of power are modeled. To improve the power quality and optimize the net power, energy storage systems are used. The results of simulation studies using General Algebraic Modeling System software confirm that by applying the proposed technique the operating costs are optimized. They confirm that the total operation costs of microgrids will be increased by considering the fuel cost and produced pollution by diesel generators. Also, by using the electric vehicles charging stations, the overall costs over 24 hours will be reduced, up to $792.
    Keywords: Energy management, Multiagent MGs, Energy Storage, electric vehicles, Pollution