• Title/Summary/Keyword: Combined cycle

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A Study on Economic Analysis of LNG Fuel Propulsion Ships using Life Cycle Cost(LCC) Based on Combined Interest Rates and Sensitivity Analysis (복합이자율과 민감도분석에 기반한 LCC 기법에 의한 LNG 연료추진 선박 경제성 평가 사례 연구)

  • Hong, Jin Pyo;Kim, Su Yeong;Kim, Chwa Jin
    • Journal of the Society of Naval Architects of Korea
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    • v.51 no.6
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    • pp.451-458
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    • 2014
  • The purpose of this study is to compare the economics between a diesel propulsion vessel and a LNG fuel propulsion vessel through the analysis of the present value using the LCC(Life Cycle Cost) method. This study is also to judge the economics for long-term operation of a LNG fuel propulsion vessel as a result of analysis about the equivalent uniform annual cost. In particular, LCC method was strengthened by sensitivity analysis based on combined interest rate which is considering discount rate and inflation rate simultaneously.

Design Study of a Dual-Mode Ramjet Engine with Large Backward-Facing Step (큰 후향 계단이 있는 이중 모드 램젯 엔진의 설계 연구)

  • Yang, Inyoung;Lee, Yang-Ji;Lee, Kyung-Jae
    • Journal of the Korean Society of Propulsion Engineers
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    • v.19 no.6
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    • pp.33-41
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    • 2015
  • Scaled model of a dual-mode ramjet engine with large backward-facing step, as a component of the rocket-based combined cycle engine, was designed. Design parameters were derived for this engine with the consideration of application for the rocket-based combined cycle engine. Design methodology was established for these design parameters. The design was partially verified through numerical study. Flow characteristics of the dual-mode ramjet engine with large backward-facing step was investigated experimentally. The design methodology for relevant design parameters established in this study was verified as feasible.

Analysis of the Influence of Anti-icing System on the Performance of Combined Cycle Power Plants (가스터빈 결빙방지 시스템이 복합화력발전 시스템의 성능에 미치는 영향)

  • Moon, Seong Won;Kim, Jeong Ho;Kim, Tong Seop
    • The KSFM Journal of Fluid Machinery
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    • v.19 no.6
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    • pp.19-25
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    • 2016
  • Anti-icing is important in gas turbines because ice formation on compressor inlet components, especially inlet guide vane, can cause performance degradation and mechanical damages. In general, the compressor bleeding anti-icing system that supplies hot air extracted from the compressor discharge to the engine intake has been used. However, this scheme causes considerable performance drop of gas turbines. A new method is proposed in this study for the anti-icing in combined cycle power plants(CCPP). It is a heat exchange heating method, which utilizes heat sources from the heat recovery steam generator(HRSG). We selected several options for the heat sources such as steam, hot water and exhaust gas. Performance reductions of the CCPP by the various options as well as the usual compressor bleeding method were comparatively analyzed. The results show that the heat exchange heating system would cause a lower performance decrease than the compressor bleeding anti-icing system. Especially, the option of using low pressure hot water is expected to provide the lowest performance reduction.

Fault Location and Classification of Combined Transmission System: Economical and Accurate Statistic Programming Framework

  • Tavalaei, Jalal;Habibuddin, Mohd Hafiz;Khairuddin, Azhar;Mohd Zin, Abdullah Asuhaimi
    • Journal of Electrical Engineering and Technology
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    • v.12 no.6
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    • pp.2106-2117
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    • 2017
  • An effective statistical feature extraction approach of data sampling of fault in the combined transmission system is presented in this paper. The proposed algorithm leads to high accuracy at minimum cost to predict fault location and fault type classification. This algorithm requires impedance measurement data from one end of the transmission line. Modal decomposition is used to extract positive sequence impedance. Then, the fault signal is decomposed by using discrete wavelet transform. Statistical sampling is used to extract appropriate fault features as benchmark of decomposed signal to train classifier. Support Vector Machine (SVM) is used to illustrate the performance of statistical sampling performance. The overall time of sampling is not exceeding 1 1/4 cycles, taking into account the interval time. The proposed method takes two steps of sampling. The first step takes 3/4 cycle of during-fault and the second step takes 1/4 cycle of post fault impedance. The interval time between the two steps is assumed to be 1/4 cycle. Extensive studies using MATLAB software show accurate fault location estimation and fault type classification of the proposed method. The classifier result is presented and compared with well-established travelling wave methods and the performance of the algorithms are analyzed and discussed.

Performance Analysis of a Gas Turbine for Power Generation Using Syngas as a Fuel (Syngas를 연료로 사용하는 발전용 가스터빈의 성능해석)

  • Lee, Jong-Jun;Cha, Kyu-Sang;Sohn, Jeong-Lak;Joo, Yong-Jin;Kim, Tong-Seop
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.32 no.1
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    • pp.54-61
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    • 2008
  • Integrated Gasification Combined Cycle (IGCC) power plant converts coal to syngas, which is mainly composed of hydrogen and carbon monoxide, by the gasification process and produces electric power by the gas and steam turbine combined cycle power plant. The purpose of this study is to investigate the influence of using syngas in a gas turbine, originally designed for natural gas fuel, on its performance. A commercial gas turbine is selected and variations of its performance characteristics due to adopting syngas is analyzed by simulating off-design gas turbine operation. Since the heating value of the syngas is lower, compared to natural gas, IGCC plants require much larger fuel flow rate. This increases the gas flow rate to the turbine and the pressure ratio, leading to far larger power output and higher thermal efficiency. Examination of using two different syngases reveals that the gas turbine performance varies much with the fuel composition.

An Analysis of the Performance of a Combined Expander-Compressor Unit for a CO2 Automotive Air Conditioning Cycle (차량용 CO2 에어컨 사이클 성능 향상을 위한 일체형 팽창기-압축기 성능 해석)

  • Choi, Jae Woong;Lim, Jeong Taek;Kim, Hyun Jin
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.30 no.3
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    • pp.107-115
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    • 2018
  • A design combining the use of a compressor and expander was introduced in order to improve the cycle performance of a $CO_2$ automotive air conditioning system. Both the compressor and expander used were of rotary vane type and were designed to share a common shaft in a housing. Numerical simulation was carried out to evaluate the merit of the combined unit. In a typical automotive air conditioning operating conditions, the COP of the system was improved by 8.7% by the application of the combined unit. The compressor input was reduced by 5.2% through use of the expander output. In addition, about 3.06% increase in the cooling capacity was obtained through isentropic expansion in the expander. Our study noted that, as the pressure difference between the gas cooler and the evaporator becomes larger, the COP of the system improved increases unless the mass flow rate in the expander exceeds that in the compressor.

Theoretical Characteristics of Thermodynamic Performance of Combined Heat and Power Generation with Parallel Circuit using Organic Rankine Cycle (유기랭킨사이클을 이용한 병렬 열병합 발전시스템의 열역학적 이론 성능 특성)

  • Kim, Kyoung-Hoon
    • Journal of the Korean Solar Energy Society
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    • v.31 no.6
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    • pp.49-56
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    • 2011
  • In this study a novel cogeneration system driven by low-temperature sources at a temperature level below $190^{\circ}C$ is investigated by first and second laws of thermodynamics. The system consists of Organic Rankine Cycle(ORC) and an additional heat generation as a parallel circuit. Seven working fluids of R143a, R22, R134a, R152a, $iC_4H_{10}$(isobutane), $C_4H_{10}$(butane), and R123a are considered in this work. Maximum mass flow rate of a working fluid relative to that of the source fluid and optimum turbine inlet pressure are considered to extract maximum power from the source. Results show that due to a combined heat and power generation, both the efficiencies by first and second laws can be significantly increased in comparison to a power generation, however, the second law efficiency is more resonable in the investigation of cogeneration systems. Results also show that the working fluid for the maximum system efficiency depends on the source temperature.

Economical and Environmental Study on SNG Combined Cycle Integrated with CCS for Large-Scale Reduction of CO2 (Based on NETL Report) (대용량 CO2 감축을 위한 CCS 연계 SNGCC의 경제성 및 환경성에 대한 연구(NETL 보고서를 중심으로))

  • SEO, DONG-KYUN;KWON, WON SOON
    • Transactions of the Korean hydrogen and new energy society
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    • v.26 no.5
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    • pp.499-506
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    • 2015
  • Recently the Korean government announced its decision to select the $3^{rd}$ proposal, which targets reducing $CO_2$ by 37% of the BAU level by 2030, for the Intended Nationally Determined Contribution (INDC). According to this proposal, natural gas (or equivalent gas) combined cycle (NGCC) are suggested as alternatives for conventional pulverized coal (PC). In this study, we analyzed the environmental, economic, and energy mixing aspects of synthetic natural gas combined cycle(SNGCC) using NETL material (2011~2012 version) and other domestic materials (2014 version). We found the following conclusions: 1) Considering carbon capture and storage (CCS) integration, $CO_2$ emission factors of SNGCC and supercritical PC are the same. However, 60% of $CO_2$ from SNGCC is produced as high pressure and high purity (99%) gas, making it highly suitable for CCS, which is now strongly supported by the government. 2) Based on the economic analysis for SNGCC using domestic materials and comparison with NGCC, it was found that the settlement price of SNGCC was 30% lower than that of NGCC.

Evaluation by Rocket Combustor of C/C Composite Cooled Structure for Combined-cycle Engine

  • Takegoshi, Masao;Ono, Fumiei;Ueda, Shuichi;Saito, Toshihito;Hayasaka, Osamu
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2008.03a
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    • pp.804-809
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    • 2008
  • In this study, the cooling performance of a C/C composite material structure with metallic cooling tubes fixed by elastic force without chemical bonding was evaluated experimentally using combustion gas in a rocket combustor. The C/C composite chamber was covered by a stainless steel outer shell to maintain its airtightness. Gaseous hydrogen as a fuel and gaseous oxygen as an oxidizer were used for the heating test. The surface of these C/C composites was maintained below 1500 K when the combustion gas temperature was about 2900 K and heat flux to the combustion chamber wall was about 9 $MW/m^2$. No thermal damage was observed on the stainless steel tubes which were in contact with the C/C composite materials. Results of the heating test showed that such a metallic-tube-cooled C/C composite structure is able to control the surface temperature as a cooling structure(also as a heat exchanger), as well as indicating the possibility of reducing the amount of the coolant even if the thermal load to the engine is high. Thus, application of the metallic-tube-cooled C/C composite structure to reusable engines such as a rocket-ramjet combined cycle engine is expected.

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Reliability-based combined high and low cycle fatigue analysis of turbine blade using adaptive least squares support vector machines

  • Ma, Juan;Yue, Peng;Du, Wenyi;Dai, Changping;Wriggers, Peter
    • Structural Engineering and Mechanics
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    • v.83 no.3
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    • pp.293-304
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    • 2022
  • In this work, a novel reliability approach for combined high and low cycle fatigue (CCF) estimation is developed by combining active learning strategy with least squares support vector machines (LS-SVM) (named as ALS-SVM) surrogate model to address the multi-resources uncertainties, including working loads, material properties and model itself. Initially, a new active learner function combining LS-SVM approach with Monte Carlo simulation (MCS) is presented to improve computational efficiency with fewer calls to the performance function. To consider the uncertainty of surrogate model at candidate sample points, the learning function employs k-fold cross validation method and introduces the predicted variance to sequentially select sampling. Following that, low cycle fatigue (LCF) loads and high cycle fatigue (HCF) loads are firstly estimated based on the training samples extracted from finite element (FE) simulations, and their simulated responses together with the sample points of model parameters in Coffin-Manson formula are selected as the MC samples to establish ALS-SVM model. In this analysis, the MC samples are substituted to predict the CCF reliability of turbine blades by using the built ALS-SVM model. Through the comparison of the two approaches, it is indicated that the reliability model by linear cumulative damage rule provides a non-conservative result compared with that by the proposed one. In addition, the results demonstrate that ALS-SVM is an effective analysis method holding high computational efficiency with small training samples to gain accurate fatigue reliability.