• Title/Summary/Keyword: 작동 변수

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Exergy analysis of R717 high-efficiency OTEC cycle (R717용 고효율 해양온도차 발전 사이클의 엑서지 분석)

  • Yoon, Jung-In;Son, Chang-Hyo;Yang, Dong-Il;Kim, Hyeon-Uk;Kim, Hyeon-Ju;Lee, Ho-Saeng
    • Journal of Advanced Marine Engineering and Technology
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    • v.37 no.8
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    • pp.829-835
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    • 2013
  • This paper describes an analysis on exergy efficiency of proposed high-efficiency R717 OTEC power system to optimize the design for the operating parameters of this system. The operating parameters considered in this study include outlet pressure in an evaporator and high turbine, inlet pressure condenser and vapor quality at cooler outlet, respectively. The main results are summarized as follows : As the outlet pressure in an evaporator and vapor quality at cooler outlet of R717 OTEC power system increases, the exergy efficiency of this system increases, respectively. But outlet pressure in the high turbine, inlet pressure in the condenser of R717 OTEC power system increases, the exergy efficiency of this system decreases, respectively. And, incase of exergy efficiency of this OTEC system, the effect of inlet pressure in an evaporator and outlet pressure in the high turbine on R717 OTEC power system is the largest and the lowest among operation parameters, respectively.

Performance Characteristics of R744 OTEC Power Cycle with Operation Parameters (운전조건에 따른 R744용 해양온도차 발전 사이클의 성능 특성)

  • Yoon, Jung-In;Son, Chang-Hyo;Baek, Seung-Moon;Kim, Hyeon-Ju;Lee, Ho-Saeng
    • Journal of Advanced Marine Engineering and Technology
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    • v.36 no.5
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    • pp.580-585
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    • 2012
  • In this paper, the cycle performance analysis for condensation and evaporation capacity, total work and efficiency of ocean thermal energy conversion power system using R744 ($CO_2$) is presented to offer the basic design data for the operating parameters of this system. The operating parameters considered in this study include superheating and subcooling degree, evaporation and condensation temperature, pump and turbine efficiency. The main results were summarized as follows : The evaporation capacity of R744 increases with superheating and subcooling degree, but decreases with the increasing condensation temperature. The total work increases with superheating and subcooling degree of R744, but decreases with the increasing evaporating temperature. And, the efficiency increases with subcooling and superheating degree, but decreases with the increasing condensation temperature. Therefore, superheating and subcooling degree, evaporation and condensation temperature and pump and turbine efficiency of R744 OTEC power system have an effect on the evaporation and condensation capacity, total work and efficiency of this system. With a thorough grasp of these effect, it is necessary to design the OTEC power cycle using R744.

Exergy Analysis of R744 OTEC Power Cycle with Operation Parameters (작동변수에 따른 R744용 해양온도차 발전 사이클의 엑서지 분석)

  • Yoon, Jung-In;Son, Chang-Hyo;Baek, Seung-Moon;Kim, Hyeon-Ju;Lee, Ho-Saeng
    • Journal of Advanced Marine Engineering and Technology
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    • v.36 no.8
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    • pp.1036-1042
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    • 2012
  • This paper describes an analysis on exergy efficiency of R744 OTEC power system to optimize the design for the operating parameters of this system. The operating parameters considered in this study include subcooling and superheating degree, evaporation and condensation temperature, and turbine and pump efficiency, respectively. The main results are summarized as follows : As the evaporation temperature, superheating degree, and turbine and pump efficiency of R744 OTEC power system increases, the exergy efficiency of this system increases, respectively. But condensation temperature and subcooling degree of R744 OTEC power system increases, the exergy efficiency of this system decreases, respectively. The effect of evaporation temperature and pump efficiency on R744 OTEC power system is the largest and the lowest among operation parameters, respectively. Therefore, the refrigerant temperature in the evaporator must be closely to the surface seawater temperature to enhance the exergy efficiency of R744 OTEC power system.

Performance Analysis of an Ammonia(R717) and Carbon Dioxide(R744) Two-Stage Cascade Refrigeration System ($NH_3-CO_2$를 사용하는 이원 냉동 시스템의 성능 분석)

  • Son, Chang-Hyo
    • Journal of the Korean Institute of Gas
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    • v.14 no.1
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    • pp.1-7
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    • 2010
  • In this paper, cycle performance analysis of $NH_3-CO_2$(R717-R744) two-stage cascade refrigeration system is presented to offer the basic design data for the operating parameters of the system. The operating parameters considered in this study include subcooling and superheating degree, compressor efficiency, and condensing and evaporating temperature in the ammonia(R717) high temperature cycle and the carbon dioxide low temperature cycle. The main results were summarized as follows : The COP of two-stage cascade refrigeration system increases with the increasing subcooling degree, but decreases with the increasing superheating degree. The COP of two-stage cascade refrigeration system decreases with the increasing condensing temperature, but increases with the increasing evaporating temperature. And the COP of two-stage cascade refrigeration system increases with increasing the compressor efficiency. Therefore, superheating and subcoolng degree, compressor efficiency, and evaporating and condensing temperature of $NH_3-CO_2$(R717-R744) two-stage cascade refrigeration system have an effect on the COP of this system.

Flow Characteristics of R600a in an Adiabatic Capillary Tube (단열 모세관내 R600a의 유동 특성)

  • Ku, Hak-Geun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.11 no.2
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    • pp.449-454
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    • 2010
  • In this paper, flow characteristics of R600a in an adiabatic capillary tube were investigated employing the homogeneous flow model. The model is based on fundamental equations of mass, energy and momentum which are solved simultaneously. Two friction factors(Churchill) and viscosity(McAdams) are comparatively used to investigate the flow characteristics. Thermodynamic and transport properties of R600a are calculated employing EES property code. Flow characteristics analysis of R600a in an adiabatic capillary tube is presented to offer the basic design data for the operating parameters. The operating parameters considered in this study include condensation temperature, evaporation temperature, subcooling degree and inner diameter tube of the adiabatic capillary tube. The main results were summarized as follows: condensation and evaporation temperature, inlet subcooling degree and inner diameter tube of an adiabatic capillary tube using R600a have an effect on length of an adiabatic capillary tube. The length of an adiabatic capillary tube using R600a is expressed to the correlation shown in Eq. (15).

Performance Characteristics of Cascade Refrigeration System Using R744 and R410A (R744-R410A용 이원 냉동시스템 성능 특성)

  • Ku, Hak-Keun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.14 no.4
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    • pp.1548-1554
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    • 2013
  • This paper presents the analysis on performance characteristics of R744-R410A cascade refrigeration system to offer the basic design data for the operating parameters of this system. The performance of cascade refrigeration system is analyzed by using EES program. The operating parameters include compressor efficiency, and condensing and evaporating temperature in R410A high- and R744 low-temperature cycle, respectively. The COP of this system increases with the decrease of condensing temperature, and increases with the increasing evaporating temperature. And the COP of this system increases with the compression efficiency. Therefore, it can be seen that the compression efficiency, and evaporating and condensing temperature of R744-R410A cascade refrigeration system have an effect on the COP of this system. Also, it can be known that the cascade evaporation temperature with the highest efficiency in each parameter is present. Thus, it is an important to design R744-R410A cascade refrigeration system by considering these parameters.

Modeling of PEM Fuel Cell System-Sensitivity Analysis of System Efficiency with Different Main Operating Parameters of Automotive Fuel Cell System (PEM 연료전지 시스템 모델링-자동차용 연료전지 시스템의 주요 작동 변수 변경에 따른 시스템 효율 민감도 분석)

  • KIM, HAN-SANG;KANG, BYUNGGIL;WON, KWONSANG
    • Transactions of the Korean hydrogen and new energy society
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    • v.30 no.5
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    • pp.401-410
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    • 2019
  • The operating conditions greatly impact the efficiency and performance of polymer electrolyte membrane (PEM) fuel cell systems and must be properly managed to ensure better performance and efficiency. In particular, small variations in operating conditions interact with each other and affect the performance and efficiency of PEM fuel cell systems. Thus, a systematic study is needed to understand how small changes in operating conditions affect the system performance and efficiency. In this paper, an automotive fuel cell system (including cell stack and balance of plant [BOP]) with a turbo-blower was modeled using MATLAB/Simulink platform and the sensitivity analyses of main operating parameters were performed using the developed system model. Effects of small variations in four main parameters (stack temperature, cathode air stoichiometry, cathode pressure, and cathode relative humidity) on the system efficiency were investigated. The results show that cathode pressure has the greatest potential impact on the sensitivity of fuel cell system efficiency. It is expected that this study can be used as a basic guidance to understand the importance of achieving accurate control of the fuel cell operating conditions for the robust operation of automotive PEM fuel cell systems.

Performance Analysis of R744(Carbon Dioxide) for Transcritical Refrigeration System (R744용 초임계 냉동사이클의 성능 분석)

  • Roh, Geun-Sang;Son, Chang-Hyo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.10 no.1
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    • pp.32-38
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    • 2009
  • In this paper, cycle performance analysis for cooling capacity, compression work and COP of R744($CO_2$) transcritical vapor compression refrigeration system is presented to offer the basic design data for the operating parameters of the system. The operating parameters considered in this study include superheating degree, outlet temperature of gas cooler and evaporating temperature in the R744 vapor compression cycle. The main results were summarized as follows : The cooling capacity of R744 increases with superheating degree, but decreases with the increasing evaporating temperature and outlet temperature of gas cooler. The compression work increases with superheating degree and cooling pressure of R744, but decreases with the increasing evaporating temperature. And, The COP increases with outlet temperature and evaporating temperature of R744 gas cooler, but decreases with the increasing superheating degree. Therefore, superheating degree, outlet temperature and evaporating temperature of R744 vapor compression refrigeration system have an effect on the cooling capacity, compression work and COP of this system. With a thorough grasp of these effect, it is necessary to design the compression refrigeration cycle using R744.

Study on Spray Atomization Characteristics Depending on the Operating Parameters of Urea Injector (요소수 인젝터의 작동 변수에 따른 분무미립화 성능에 관한 연구)

  • Kim, Donghwan;Park, Junkyu;Park, Sungwook
    • Journal of ILASS-Korea
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    • v.24 no.1
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    • pp.1-7
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    • 2019
  • This study was carried out to analyze the spray characteristics as a function of the operating parameters of urea injector used in Urea-SCR system of passenger diesel vehicle. Spray visualization and PDPA experiment were performed to analyze the macroscopic spray development and atomization performance of urea-water-solution. For the urea injector, the deformation of the spray head does not appear to be significant because it operates at a low pressure conditions, and the liquid core and primary droplet are observed throughout the operating conditions. No increase in atomization is seen when the operating pressure is increased, and the spray develops linearly due to poor atomization characteristics. The macroscopic spray behavior of the low-pressure urea injector is predictable through the modification of the Hiroyasu equation.

Study on the Combustion Performance Estimation of Hydrazine Mono Propellant Thruster (하이드라진 단일 추진제 추력기의 연소 성능예측에 관한 연구)

  • 정인석;윤영빈;최정열;김철중;명대근;정기훈
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.30-30
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    • 1998
  • 다목적 실용위성의 자세 제어용으로 장착되는 하이드라진 단일 추진제 추력기의 연소성능 특성을 살펴보았다. 일차적으로, 연소기내의 화학 평형 계산을 통하여 하이드라진 연소 생성물인 암모니아의 분해율과 초기 엔탈피 수준에 따른 추력기의 성능 특성을 살펴보았다. 다음 순서로, 연소기 내의 비평형 화학 반응 계산을 통하여 연소진행 시간에 화학 조성 및 성능 특성을 살펴 볼 수 있었으며, 최종적으로, 점성 및 비점성, 동결 및 비평형 화학 반응 해석에 따른 성능 특성 변화를 살펴보았다. 본 연구 결과로부터 각 작동 변수에 따른 추격기 성능 특성의 변화를 이해할 수 있었으며, 이는 단일 추진제 추력기 연소실의 구성, 설계 및 추력기의 운용 조건 설정에 중요한 자료로 이용될 수 있을 것으로 기대된다.

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