• Title/Summary/Keyword: Energy Systems

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Comparison of Energy Performance between Ground-Source Heat Pump System and Variable Refrigerant Flow(VRF) Systems using Simulation (시뮬레이션을 통한 지열 히트펌프 시스템과 VRF 시스템의 에너지 성능비교)

  • Sohn, Byonghu;Lim, Hyojae;Kang, Seongjae
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.17 no.3
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    • pp.30-40
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    • 2021
  • This paper compares the annual energy performance of four different types of air-conditioning systems in a medium-sized office building. Chiller and boiler, air-cooled VRF, ground-source VRF, and ground-source heat pump systems were selected as the systems to be compared. Specifically, the energy performance of the GSHP system and the ground-source VRF system were compared with each other and also with conventional HVAC systems including the chiller and boiler system and air-cooled VRF system. In order to evaluate and compare the energy performances of four systems for the office building, EnergyPlus, a whole-building energy simulation program, was used. The EnergyPlus simulation results show that both the GSHP and the ground-source VRF systems not only save more energy than the other two systems but also significantly reduce the electric peak demand. These make the GSHP and the VRF systems more desirable energy-efficient HVAC technologies for the utility companies and their clients. It is necessary to analyze the impact of partial load performance of ground-source heat pump and ground-source VRF on the long-term (more than 20 years) performance of ground heat exchangers and entire systems.

A Study on the Optimization of New Renewable Energy Systems in Public-Purpose Facilities (공공용 업무시설의 신재생에너지시스템 최적화 연구)

  • Lee, Yong-Ho;Seo, Sang-Hyun;Cho, Young-Hum;Hwang, Jung-Ha
    • Journal of the Korean Solar Energy Society
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    • v.33 no.5
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    • pp.95-104
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    • 2013
  • This study set out to devise an optimized system to take into account life cycle cost(LCC) and ton of carbon dioxide($TCO_2$) by applying the weighted coefficient method(WCM) to "public-purpose" facility buildings according to the mandatory 5% and 11% of new renewable energy in total construction costs and anticipated energy consumption, respectively, based on the changes of the public obligation system. (1) System installation capacity is applied within the same new renewable energy facility investment according to the mandatory 5% of new renewable energy in total construction costs. Both LCC and $TCO_2$ recorded in the descending order of geothermal, solar, and photovoltaic energy. The geothermal energy systems tended to exhibit an excellent performance with the increasing installation capacity percentage. (2) Optimal systems include the geothermal energy(100%) system in the category of single systems, the solar energy(12%)+geothermal energy(88%) system in the category of 2-combined systems, and the photovoltaic energy(12%)+solar energy(12%)+geothermal energy(76%) system and the photovoltaic energy(12%)+solar energy(25%)+geothermal energy(63%) system in the category of 3-combined systems. (3) LCC was the highest in the descending order of photovoltaic, geothermal and solar energy due to the influences of each energy source's correction coefficient according to the mandatory 11% of new renewable energy in anticipated energy consumption. The greater installation capacity percentage photovoltaic energy had, the more excellent tendency was observed. $TCO_2$ recorded in the descending order of geothermal, photovoltaic and solar energy with the decreasing installation capacity of photovoltaic energy. The greater installation capacity percentage a geothermal energy system had, the more excellent tendency it demonstrated. (4) Optimal systems include the geothermal energy(100%) system in the category of single systems, the photovoltaic energy(62%)+geothermal energy(38%) system in the category of 2-combined systems, and the photovoltaic energy(50%)+solar energy(12%)+geothermal energy(38%) system and the photovoltaic energy(12%)+solar energy(12%)+geothermal energy(76%) system in the category of 3-combined systems.

A Study on the Validation Methodology of Network Analysis Applications in Energy Management Systems (계통운영시스템 계통해석 프로그램 검증 방안에 관한 연구)

  • Cho, Yoon-Sung
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.28 no.10
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    • pp.27-36
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    • 2014
  • Network analysis applications in energy management systems play a key role in the economic and reliable operation of power systems. In order to provide operators with useful network information, the accurate results of topology processing, state estimation, power flow, and contingency analysis must be simulated. This paper proposes a validation methodology of network analysis applications in energy management systems. The energy management systems was checked to ensure that it meets the originally specified functions based on the proposed methodology. In addition, the performance of state estimation is evaluated with the reference of the proposed methodology. The proposed methodology is being conducted by energy management systems and the Korean power systems have been utilized for the test systems.

Preliminary Feasibility Study on Wind and Solar Hybrid Power Systems based on Venturi Effects for Buildings (벤투리 효과를 활용한 도심형 건물용 하이브리드 풍력 및 태양광 발전 시스템 기초타당성 예비연구)

  • Suhyun Kim;Yoonsoo Kim;Sumin Park;Jihyeon An;Sanghun Lee
    • New & Renewable Energy
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    • v.19 no.1
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    • pp.22-30
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    • 2023
  • Recently, the use of renewable energy has been increasing to achieve carbon neutrality. The concept of a zero-energy building is also attracting attention. In this study, a preliminary study was conducted to analyze the feasibility of a hybrid wind and solar power generation system between buildings that utilize the building wind generated by the Venturi effect. For this purpose, the wind speed and sunshine hours were monitored in the area where the building wind blows by the Venturi effect, and the power generation depending on system types, areas, and season was estimated. Consequently, the wind power generation system showed a larger amount of power per area than solar power. The wind power systems can generate larger power if wind power blades are installed along the height of the building. As a preliminary study, this study verified the feasibility of the system utilizing building wind and suggested follow-up studies.

Economic Evaluations of Secondary Battery Energy Storage Systems in Power Distribution Systems (전력저장전지시스템의 경제성 평가)

  • No, Dae-Seok;O, Yong-Taek
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.49 no.4
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    • pp.152-160
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    • 2000
  • This paper presents an efficient evaluation method on the role of new energy storage systems, especially the secondary Battery Energy Storage (BES) systems, in the case where they are interconnected with the power distribution systems. It is important to perform the economic evaluation for the new energy storage systems in a synthetical and quantitative manner, because they are very costly in the early stage of their development and commercialization. In this paper, the multiple functions of BES systems, which are operated at distribution systems, such as load levelling, effective utilization of power distribution systems and uninterruptible power supply at the emergency conditions are classified and analyzed. And then the quantitative evaluation methods of the multiple functions for BES systems are proposed using the mathematical modelling.

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Hydrogen Generation by Electrical Discharge Through Metal / Water System

  • Park, Yong-Man;Kang, Goo-Jin;Cha, Suk-Yal;Lee, Woong-Moo
    • Journal of Energy Engineering
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    • v.5 no.2
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    • pp.198-202
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    • 1996
  • Reactive metals like aluminum generate hydrogen gas when it reacts with water. Aluminum, despite its high chemical affinity with water, cannot continue the reaction due to the passive oxide layers formed on its surface. When the reaction is assisted by electrical energy dissipation in the form of discharge, the reaction is more likely to be sustained. In this report, some preliminary experimental results are presented regarding the hydrogen generation based on this scheme.

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Performance Test of 2 kW Class Reverse Brayton Refrigeration System (냉동능력 2 kW 급 역브레이튼 극저온 냉각시스템 성능시험)

  • KO, JUNSEOK;LEE, KEUN-TAE;PARK, SEONG-JE;KIM, JONGWOO;CHOO, SANGYOON;HONG, YONG-JU;IN, SEHWAN;PARK, JIHO;KIM, HYOBONG;YEOM, HANKIL
    • Transactions of the Korean hydrogen and new energy society
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    • v.31 no.5
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    • pp.429-435
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    • 2020
  • This paper describes the experimental study of reverse-Brayton refrigeration system for application to high temperature superconductivity electric devices and LNG re-liquefaction. The reverse-Brayton refrigeration cycle is designed with operating pressure of 0.5 and 1.0 MPa, cooling capacity of 2 kW at 77 K, and neon as a working fluid. The refrigeration system is developed with multi scroll compressor, turbo expander and plate heat exchanger. From experiments, the performance characteristics of used components is measured and discussed for 77-120 K of operating temperature. The developed refrigeration system shows the cooling capacity of 1.23 kW at 77 K and 1.64 kW at 110 K.

Conceptual Design Strategy of Renewable Energy Application for Building Certification and Mandatory System (신재생에너지설비 건물설치 의무화 및 인증제를 고려한 용량설계 방안)

  • Lee, Kyoung-Ho;Lee, Dong-Won;Kown, Hyeok-Min;Lee, Chang-Jun
    • 한국태양에너지학회:학술대회논문집
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    • 2011.11a
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    • pp.99-104
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    • 2011
  • This paper describes a design strategy at conceptual design stage using RETScreen software tool for building application of renewable energy resources. Currently, government and public buildings are required to adopt renewable energy systems with a minimum requirement for the amount of renewable energy supply. Meanwhile, there is a certificate program for private office buildings to enhance propagation of renewable energy systems. When considering application of renewable energy systems to a building, it is worthwhile developing a method to determine optimal design sizes of renewable energy systems. In the paper, a design strategy is introduced with a couple of case studies to determine optimal capacities of each renewable energy system in a building and suggest to use the method to evaluate the system for the building certificate program and the mandatory renewable target program. Objective functions considered in the study are initial system cost and reduction of CO2 emissions from the system. In the optimization study, it is assumed that solar thermal collectors are installed to satisfy solar fraction of 60%. Other renewable energy systems such as ground-source heat pump, solar PV and non-renewable systems such as electric chiller and gas-fired boiler are sized using an optimal sizing method with RETScreen suggested the authors previously.

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Monte Carlo simulations for gamma-ray spectroscopy using bismuth nanoparticle-containing plastic scintillators with spectral subtraction

  • Taeseob Lim ;Siwon Song ;Seunghyeon Kim ;Jae Hyung Park ;Jinhong Kim;Cheol Ho Pyeon;Bongsoo Lee
    • Nuclear Engineering and Technology
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    • v.55 no.9
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    • pp.3401-3408
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    • 2023
  • In this study, we used the Monte Carlo N-Particle program to simulate the gamma-ray spectra obtained from plastic scintillators holes filled with bismuth nanoparticles. We confirmed that the incorporation of bismuth nanoparticles into a plastic scintillator enhances its performance for gamma-ray spectroscopy using the subtraction method. The subtracted energy spectra obtained from the bismuth-nanoparticle-incorporated and the original plastic scintillator exhibit a distinct energy peak that does not appear in the corresponding original spectra. We varied the diameter and depth of the bismuth-filled holes to determine the optimal hole design for gamma-ray spectroscopy using the subtraction method. We evaluated the energy resolutions of the energy peaks in the gamma-ray spectra to estimate the effects of the bismuth nanoparticles and determine their optimum volume in the plastic scintillator. In addition, we calculated the peak-to-total ratio of the energy spectrum to evaluate the energy measuring limit of the bismuth nanoparticle-containing plastic scintillator using the subtraction method.

Trends in Mobile Network Energy-Saving Technology (모바일 네트워크 에너지 절감 기술 동향)

  • S. Jung;S.-E. Hong;J. Na
    • Electronics and Telecommunications Trends
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    • v.38 no.2
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    • pp.26-35
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    • 2023
  • Energy efficiency is an important factor toward sustainable future mobile network systems. As the size of the 5G mobile network system increases, the consumption and costs of energy increase. Accordingly, energy-saving optimization has become a major process in network systems, and various related technologies for energy saving are being developed. We provide a brief review of the technical trends in energy saving in 3GPP 5G & 5G Advanced systems and O-RAN systems. We focus on power models and energy-saving technologies in various resource domains of 3GPP 5G & 5G Advanced systems and energy-saving use cases of O-RAN systems.