• 제목/요약/키워드: primary energy use

검색결과 236건 처리시간 0.028초

Assessment of dynamic crushing and energy absorption characteristics of thin-walled cylinders due to axial and oblique impact load

  • Baaskaran, N.;Ponappa, K.;Shankar, S.
    • Steel and Composite Structures
    • /
    • 제28권2호
    • /
    • pp.179-194
    • /
    • 2018
  • Reliable and accurate method of computationally aided design processes of advanced thin walled structures in automotive industries are much essential for the efficient usage of smart materials, that possess higher energy absorption in dynamic compression loading. In this paper, most versatile components i.e., thin walled crash tubes with different geometrical profiles are introduced in view of mitigating the impact of varying cross section in crash behavior and energy absorption characteristics. Apart from the geometrical parameters such as length, diameter and thickness, the non-dimensionalized parameters of average forces which control the plastic bending moment for varying thickness has explored in view of quantifying its impact on the crashworthiness of the structure. The explicit finite element code ABAQUS is utilized to conduct the numerical studies to examine the effect of parametric modifications in crash behavior and energy absorption. Also the simulation results are experimentally validated. It is evident that the circular cross-sectional tubes are preferable as high collision impact shock absorbers due to their ability in withstanding axial and oblique impact loads effectively. Furthermore, the specific energy absorption (SEA), crash force efficiency (CFE), plastic bending moment, peak force responses and its impact for optimally tailoring a design to cater the crashworthiness requirements are investigated. The primary outcome of the study is to provide sufficient information on circular tubes for the use of energy absorbers where impact oblique loading is expected.

Investigation of two-phase natural circulation with the SMART-ITL facility for an integral type reactor

  • Jeon, Byong Guk;Yun, Eunkoo;Bae, Hwang;Yang, Jin-Hwa;Ryu, Sung-Uk;Bang, Yun-Gon;Yi, Sung-Jae;Park, Hyun-Sik
    • Nuclear Engineering and Technology
    • /
    • 제54권3호
    • /
    • pp.826-833
    • /
    • 2022
  • A two-phase natural circulation test using SMART integral test loop (SMART-ITL) was conducted to explore thermo-hydraulic phenomena of two-phase natural circulation in the SMART reactor. Specifically, the test examined the natural circulation in the primary loop under a stepwise coolant inventory loss while keeping the core power constant at 5% of the scaled full power. Based on the test results, three flow regimes were observed: single-phase natural circulation (SPNC), two-phase natural circulation (TPNC), and boiler-condenser natural circulation (BCNC). The flow rate remained steady in the SPNC, slightly increased in the TPNC, and dropped abruptly and maintained in the BCNC. Using a natural circulation flow map, the natural circulation characteristic in the SMART-ITL was compared with those in pressurized water reactor simulators. In the SMART-ITL, a BCNC regime appeared instead of siphon condensation and reflux condensation regimes because of the use of once-through steam generators.

A proposal on SOFC-PEMFC combined system for maritime applications

  • Duong Phan Anh;Ryu Borim;Nguyen Quoc Huy;Lee Jinuk;Kang Hokeun
    • 한국항해항만학회:학술대회논문집
    • /
    • 한국항해항만학회 2022년도 추계학술대회
    • /
    • pp.162-163
    • /
    • 2022
  • Maritime transportation is going to transfer to alternative fuels as a result of the worldwide demands toward decarbonization and tougher maritime emissions regulations. Methanol is considered as a potential marine fuel, which has the ability to reduce SOx and CO2 emissions, reduce climate change effects, and achieve the objective of green shipping. This work proposes and combines the innovative combination system of direct methanol solid oxide fuel cells (SOFC), proton exchange membrane fuel cells (PEMFC), gas turbines (GT), and organic Rankine cycles (ORC) for maritime vessels. The system's primary power source is the SOFC, while the GT and PEMFC use the waste heat from the SOFC to generate useful power and improve the system's ability to use waste heat. Each component's thermodynamics model and the combined system's model are established and examined. The multigeneration system's energy and exergy efficiency are 76.2% and 30.3%, respectively. When compared to a SOFC stand-alone system, the energy efficiency of the GT and PEMFC system is increased by 19.2%. The use of PEMFC linked SOFC has significant efficiency when a ship is being started or maneuvered and a quick response from the power and propulsion plant is required.

  • PDF

에너지$\cdot$환경 제반 시스템에 관한 수치 해석적 연구 (Ⅰ) : LPG 확산, 호소 유동, 일차침전조, 국소 환기용 후두, 싸이클론 연소로, Dow 화학 반응로 (A Numerical Study On Various Energy and Environmental Systems(Ⅰ) : LPG dispersion, Lake flow, Primary clarifier, Hood ventilation, Cyclone combustor, Dow chlorination reactor.)

  • 장동순;김경미;이은주;박병수;김복순
    • 한국전산유체공학회지
    • /
    • 제2권1호
    • /
    • pp.93-108
    • /
    • 1997
  • This paper describes several computational results on the various energy and environmental problems using Patankar's SIMPLE method. The specific problems included in this study are : pollutant and flammable material dispersions in open and confined areas, buoyancy-driven flow in a lake, primary clarifier for water and waste water treatment, hood ventilation in workplace. cyclone combustor and Dow chlorination reactor. A control-volume based finite-difference method is employed together with the power-law scheme. The pressure-velocity coupling is resolved by the use of the revised version of SIMPLE, says SIMPLER and SIMPLEC. The Reynolds stresses are closed using the standard or RNG κ-ε models. A nonequilibrium turbulent reaction model is developed for the application of the chlorination process in the Dow thermal reactor. Other important empirical models and physical insights appeared in this study are presented and discussed in a brief note. The computational method developed in this study is considered, in general, as a viable tool for the design and determination of the optimal operating condition of various environmental engineering system of interest.

  • PDF

전기자동차 충·방전제어 통합 환경을 고려한 전기차 1차 주파수 회복예비력의 계통연계형 모델링 (Gird Connected Modeling of Primary Frequency Recovery Reserve Provided by Electric Vehicle Considering Characteristics of Electric Vehicle Charge/Discharge Control Integrated Environment)

  • 국경수;이지훈;문종희;최우영;박기준;장동식
    • KEPCO Journal on Electric Power and Energy
    • /
    • 제7권2호
    • /
    • pp.249-254
    • /
    • 2021
  • As the spreading speed of electric vehicles increases rapidly, those are expected to be able to use them as flexible resources in the power system beyond the concern for the supply of its charging power. Especially when the Renewable Energy sources (RES) which have no intrinsic control capability have replaced the synchronous generators more and more, the power system needs to secure the additional frequency control resources to ensure its stability. However, the feasibility of using electric vehicles as the frequency control resources should be analyzed from the perspective of the power system operation and it requires the existing simulation frameworks for the power system. Therefore, this paper proposes the grid connected modeling of the primary frequency control provided by electric vehicles which can be integrated into the existing power system model. In addition, the proposed model is implemented considering technical performances constrained by the characteristics of the Vehicle-Grid Integration (VGI) system so that the simulation results can be accepted by the power utilities operating the power system conservatively.

Spectrum Sensing Techniques for Cognitive radio-A Review

  • Matin, Mohammad A.
    • KSII Transactions on Internet and Information Systems (TIIS)
    • /
    • 제8권11호
    • /
    • pp.3638-3654
    • /
    • 2014
  • Cognitive Radio (CR) users need to sense the environment or channel at regular time interval for sharing the spectrum band of the primary users (PUs). Once find the spectrum idle, CR users start their transmission through it. Even while transmitting, they need to continue the sensing process so that they can leave the spectrum immediately whenever find a PU wanting to use the band. Therefore, detecting PUs is one of the main functions of cognitive radio before transmission and higher the detection probability ensures better protection to the primary users. However, it is not possible to attain a high detection probability (or a low miss detection probability) and low false alarm probability simultaneously as there is a tradeoff between false alarm probability ($P_{fa}$) and the probability of detection ($P_d$). In this paper, the author has provided a comprehensive study on different sensing techniques and discussed their advantages and disadvantages. Moreover, it is expected that, with this article, readers can have a through understanding of sensing techniques in CR and the current research trends in this area.

착저식 OWC 파력발전장치의 파에너지 흡수효율 및 파랑하중 계산 (Prediction of Wave Energy Absorption Efficiency and Wave Loads of a Three-Dimensional Bottom-Mounted OWC Wave Power Device)

  • 홍도천;홍기용
    • 한국해양환경ㆍ에너지학회지
    • /
    • 제13권1호
    • /
    • pp.47-52
    • /
    • 2010
  • 근해에 설치되는 3차원 착저식 OWC 파력발전 챔버 구조물의 파 에너지 흡수효율과 구조물에 작용하는 1차 및 시간 평균 2차 파랑하중의 해석기법을 보였다. 쌍동형 OWC챔버 내부의 변동압력을 각 챔버의 내부 자유표면 경계조건에 도입하였으며 챔버 내부는 Rankine, 외부는 유한수심 3차원 자유표면 Green함수에 연계된 하이브리드 적분방정식을 사용하여 포텐셜 유동을 해석하였다. 수치실험 결과로서 3차원 착저식 OWC 파일럿 플랜트의 파력발전 1차변환 효율과 구조물에 작용하는 반복 및 지속적인 파랑하중을 제시하였다.

System Design and Evaluation of a Compact and High Energy X-ray Talbot-Lau Grating Interferometer for Industrial Applications

  • Lee, Seho;Oh, Ohsung;Kim, Youngju;Lee, Seung Wook;Kim, Insoo;Kim, Jinkyu
    • Journal of the Korean Physical Society
    • /
    • 제73권12호
    • /
    • pp.1827-1833
    • /
    • 2018
  • X-ray grating interferometry has been an active area of research in recent years. In particular, various studies have been carried out for the practical use of the x-ray grating interferometer in medical and industrial fields. For the commercialization of the system, it needs to be optimized for its application. In this study, we have developed a prototype of the compact high energy x-ray grating interferometer of which the high effective energy and compactness is of our primary feature of design. We have designed the Talbot-Lau x-ray interferometer in a symmetrical geometry with an effective energy of 54.3 keV. The system has a source-to-analyzer grating distance of 788.4 mm, which is compact enough for a commercial product. In a normal operation, it took less than ten seconds to acquire a set of phase stepping images. The acquired images had a maximum visibility of about 15%, which is relatively high compared with the visibilities of the other high-energy grating interferometric systems reported so far.

건물 에너지 절감조치의 시뮬레이션 모델링 상세수준 (Level of Detail (LOD) for Building Energy Conservation Measures (ECMs))

  • 김선혜
    • KIEAE Journal
    • /
    • 제15권6호
    • /
    • pp.69-80
    • /
    • 2015
  • Purpose: Since most simulation programs take the interface that lists up all the input variables representing all the functionalities, users must know where design variables of an Energy Conservation Measure (ECM) are located and also know what values are appropriate. This is why practitioner designers feel frustrated when they attempt to use simulation. The final objective of this study is to provide a building energy modeling guideline for practitioners in various fields such as architectural design and MEP. Method: As the first step of the modeling guideline, this study provides the Level of Detail (LOD) for simulation modeling of primary ECMs considering the design information available in each design phase. It is prepared by literature review, simulation functionality investigation, and field experts' survey. Result: The proposed simulation LOD offers a milestone at each design phases concerning what design variable and attributes need to be developed with how much of details in order to meet the project goal. Also each design team can set up a simulation usecase considering organizational characteristics based on the proposed LOD.

상한론의 '기기상충(其氣上衝)'과 '계지탕(桂枝湯)'에 대한 연구 (A study of 'Ji-Qi-Shang-Chong(其氣上衝)' and Gui-Zhi-Tang(桂枝湯)in Shang-han-lun)

  • 이승준;김영목
    • 대한한의학방제학회지
    • /
    • 제20권2호
    • /
    • pp.165-176
    • /
    • 2012
  • In pathologically analyzing, 'Qi(氣)' is fall downed 'Zheng-Qi(正氣; Base energy of human body)' or 'Wai-Gan-Xie-Qi(外感邪氣; poisoned energy from outside of human body)'. And all extroverted symptoms from this 'Qi(氣)' is 'Shang-Chong(上衝)'. Also this symptom's basic mechanism is deficiency of 'Zhong-yang(中陽; basic active energy acting pivot)' by non-proper 'Xia-fa(下法; treatment way getting out focus to down side)' at early days of 'Tai-Yang-bing (太陽病; Primary stage symptoms when the cold energy of the outside tresspasses the external layer of body)'. And comparing herbs in medicines for treating 'Shang-Chong(上衝)' in Shang han lun with Japanese in Shang-han medical practitioner's view, there is 'Ping-Chong(平衝; Supress out bursting energy)''s effect when use 'Gui-zhi(桂枝; Cinnamomum cassia loureirii zeylanuicum)' for mass dosage. Based on these, 'Qi-Shang-Chong(氣上衝)' means all of the symptom's aspects which called 'Yang(陽)''s aspect that is extrovesity, dynamic and imminent by results of the experiment about Cinnamaldehyde which are the main ingredients of 'Gui-zhi(桂枝; Cinnamomum cassia loureirii zeylanuicum)' and clinical data of 'Gui-zhi-tang(桂枝湯)'.