• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.672-675
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• 2007

Experimental data are presented which describe heat losses of cavity type receiver in wind tunnel. Experiments are conducted at various conditions such as the heater temperature in cavity changes from 300, 400, and 500 oC, wind speed in tunnel from 2 to 8 m/s, and four different tilt angle of 30, 50, 70, 90o. The power consumption including temperature, voltage and current for each experimental conditions are measured and stored in data logger at everyone second interval. The experimental results show that heat losses increase with increasing wind speed and with tilt angle. However, heat losses for the tilt angle of 70 and 90o is almost same at each heater temperature. In addition, the effects of natural convection in combined convection heat losses vary in according to the tilt angle.

• 대한기계학회논문집B
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• 제33권7호
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• pp.541-551
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• 2009

Configuration of the inlet transition square duct (hereinafter referred to as "transition duct") for heat recovery steam generator (hereinafter referred to as "HRSG") in combined cycle power plant is limited by the construction type of HRSG and plant site condition. The main purpose of the present study is to analyze the effect of a variation in turbulent flow pattern by roof slop angle change of transition duct for horizontal HRSG, which is influencing heat flux in heat transfer structure to the finned tube bank. In this study, a computational fluid dynamics(CFD) is applied to predict turbulent flow pattern and comparisons are made to 1/12th scale cold model test data for verification. Re-normalization group theory (RNG) based k-$\epsilon$ turbulent model, which improves the accuracy for rapidly strained flow and swirling flow in comparison with standard k-$\epsilon$ model, is used for the results cited in this study. To reduce the amount of computer resources required for modeling the finned tube bank, a porous media model is used.

• 한국분무공학회지
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• 제20권2호
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• pp.107-113
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• 2015

To date, the demand for Combined Cycle Power Plant (CCPP) has been continuously increased to overcome the problem of air pollution and lack of energy. In particular, the underground CCPP is exposed to substantial fire and explosion risks induced by gas leakage. The present study conducted numerical simulations to examine the fire behavior and gas leakage characteristics for a restricted region including gas turbine and other components used in a typical CCPP system. The commercial code of FLUENT V.14 was used for simulation. From the results, it was found that flammable limit distribution of leakage gas affects fire behavior. Especially, the flame is propagated in an instant in restricted region with LNG gas. In addition, consequence analysis factors such as critical temperature and radiation heat flux are introduced. These results would be useful in making the safety guidelines for the underground CCPP.

• 신재생에너지
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• 제5권2호
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• pp.15-24
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• 2009

As new small scale LFG (landfill gas) energy project model which can improve economic feasibility limited due to the economy of scale, LFG-Microturbine combined heat and power system with $CO_2$ fertilization into greenhouses was proposed and investigated including basic design process prior to the system installation at Gwang-ju metro sanitary landfill. The system features $CH_4$ enrichment for stable microturbine operation, reduction of compressor power consumption and low CO emission, and $CO_2$ supplement into greenhouse for enhancement plant growth. From many other researches, high $CO_2$ concentration was found to enhance $CO_2$ assimilation (also known as photosynthesis reaction) which converts $CO_2$ and $H_2O$ to sugar using light energy. For small scale landfills which produce LFG under $3\;m^3$/min, among currently available prime movers, microturbine is the most suitable power generation system and its low electric efficiency can be improved with heat recovery. Besides, since its exhaust gas contains very low level of harmful contaminants to plant growth such as NOx, CO and SOx, microturbine exhaust gas is a suitable and economically advantageous $CO_2$ source for $CO_2$ fertilization in greenhouse. The LFG-Microturbine combined heat and power generation system with $CO_2$ fertilization into greenhouse gas to enhance plant growth is technologically and economically feasible and improves economical feasibility compared to other small scale LFG energy project model.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.1986-1991
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• 2007

KEPRI has studied anode-supported planar SOFCs and kW class stacks operated at intermediate temperature for development of a combined heat and power unit. A single cell composed of Ni-YSZ/FL/ScSZ/LSCF showed the maximum power density of 0.55 W/$cm^2$ at $650^{\circ}C$ and 1.8 W/$cm^2$ at $750^{\circ}C$. With 37 cells of 10${\times}10cm^2$ and stainless steel interconnects, a 1kW class SOFC stack was manufactured. When a 1kW class SOFC system was operated at $750^{\circ}C$ with city gas, it showed the power output of 1.3 kWe at 50 A. It also recuperated heat of 0.57-1.2 kWth according to the loaded current through combustion of unreacted anode off-gas. Recently, KEPRI is developing a new kW class SOFC stack and system to increase efficiency and durability at intermediate temperature.

• Nuclear Engineering and Technology
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• 제39권1호
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• pp.31-42
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• 2007

Energy supply is increasingly showing up as a major issue for electricity supply, transportation, settlement, and process heat industrial supply including hydrogen production. Nuclear power is part of the solution. For electricity supply, as exemplified in Finland and France, the EPR brings an immediate answer; HTR could bring another solution in some specific cases. For other supply, mostly heat, the HTR brings a solution inaccessible to conventional nuclear power plants for very high or even high temperature. As fossil fuels costs increase and efforts to avoid generation of Greenhouse gases are implemented, a market for nuclear generated process heat will be developed. Following active developments in the 80's, HTR have been put on the back burner up to 5 years ago. Light water reactors are widely dominating the nuclear production field today. However, interest in the HTR technology was renewed in the past few years. Several commercial projects are actively promoted, most of them aiming at electricity production. ANTARES is today AREVA's response to the cogeneration market. It distinguishes itself from other concepts with its indirect cycle design powering a combined cycle power plant. Several reasons support this design choice, one of the most important of which is the design flexibility to adapt readily to combined heat and power applications. From the start, AREVA made the choice of such flexibility with the belief that the HTR market is not so much in competition with LWR in the sole electricity market but in the specific added value market of cogeneration and process heat. In view of the volatility of the costs of fossil fuels, AREVA's choice brings to the large industrial heat applications the fuel cost predictability of nuclear fuel with the efficiency of a high temperature heat source tree of Greenhouse gases emissions. The ANTARES module produces 600 MWth which can be split into the required process heat, the remaining power drives an adapted prorated electric plant. Depending on the process heat temperature and power needs, up to 80% of the nuclear heat is converted into useful power. An important feature of the design is the standardization of the heat source, as independent as possible of the process heat application. This should expedite licensing. The essential conditions for success include: ${\bullet}$ Timely adapted licensing process and regulations, codes and standards for such application and design ${\bullet}$ An industry oriented R&D program to meet the technological challenges making the best use of the international collaboration. Gen IV could be the vector ${\bullet}$ Identification of an end user(or a consortium of) willing to fund a FOAK

• Journal of Mechanical Science and Technology
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• 제17권11호
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• pp.1746-1755
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• 2003

Operating characteristics of a triple pressure reheat HRSG are analyzed using a commercial software package (Gate Cycle by GE Enter Software). The calculation routine determines all the design parameters including configuration and area of each heat exchanger. The off-design calculation part has the capability of simulating the effect of any operating parameters such as power load, process requirements, and operating mode, etc., on the transient performance of the plant. The arrangement of high-temperature and intermediate-temperature components of the HRSG is changed, and its effect on the steam turbine performance and HRSG characteristics is examined. It is shown that there could be a significant difference in HRSG sizes even though thermal performance is not in great deviation. From the viewpoint of both economics and steam turbine performance, it should be carefully reviewed whether the optimum design point could exist. Off-design performance could be one of the main factors in arranging components of the HRSG because power plants operate at various off-design conditions such as ambient temperature and gas turbine load, etc. It is shown that different heat exchanger configurations lead to different performances with ambient temperature, even though they have almost the same performances at design points.

• 에너지공학
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• 제24권3호
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• pp.67-73
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• 2015

유연탄 및 원자력과 같은 기저 발전원은 대부분 수요지와 떨어진 곳에 위치해 있어 대규모 송전시설을 필요로 하는데, 이러한 송전시설은 다양한 사회적 비용을 야기하고 있다. 반면에 집단에너지사업 열병합발전과 같은 분산형 전원은 주로 수요지 인근에 설치되어 대규모 송전시설을 필요로 하지 않기에 송전시설로 인한 피해를 회피하는 편익을 창출한다. 이에 본 논문에서는 분산형 전원의 송전망 피해 회피편익을 추정하고자 한다. 이를 위해 무작위로 추출된 전국 1,000 가구를 대상으로 조건부 가치측정법을 적용한다. 보다 구체적으로는, 현재 발전량 비중이 가장 큰 유연탄 화력발전을 통해 생산된 전력을 분산형 전원인 집단에너지사업 열병합발전을 통해 생산된 전력으로 교체하여 사용하는 것에 대한 일반 국민의 지불의사액을 추정한다. 분석결과 유연탄 화력발전 대비 집단에너지사업 열병합발전의 송전망 피해 회피편익은 41.4(원/kWh)로 추정되었으며 유의수준 1%에서 통계적으로 유의하였다. 이 값은 2014년 기준 주택용 전력 평균가격의 33%에 해당하는 값으로 분산형 전원으로서의 집단에너지사업 열병합발전의 외부편익이 작지 않음을 시사한다.

• 플랜트 저널
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• 제14권3호
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• pp.42-48
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• 2018

본 연구에서는 판형열교환기 전열면적을 25%, 50%, 75% 증가시킬 때 CHP 회수온도 변화량을 예측하고 변화된 온도를 성능해석 입력 값으로 활용하여 전기출력 변화를 해석하였다. 전열면적 투자비용과 전기 판매수익 증가를 비교하여 경제성 분석을 수행하였다. 광교 열병합발전소 연계운전이 2017년과 유사한 경향으로 이루어지면 CHP 회수온도는 전열면적 증가에 따라 $4^{\circ}C$, $6.3^{\circ}C$, $7.8^{\circ}C$까지 낮아지고 전기출력은 당초 39,025 kW에서 413 kW, 676 kW, 834 kW 증가되어 75% 증가할 경우 39,859 kW 까지 상승하였다. 경제성 분석기준인 NPV는 3.5 억원, 5억원, 5.2억원 까지 발생하여 모든 방안이 투자가치가 있다고 판단된다. 전열면적 증가에 따라 전기출력과 NPV는 비례하여 상승하지만 상승량은 감소하였다. 75%까지 증가할 경우 전기출력과 NPV는 3가지 방안 중 가장 높은 것으로 확인되었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 A
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• pp.194-195
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• 2006

미래의 전력 시스템은 환경과 기술적인 이유로 인해 더욱더 많은 분산전원을 이용하게 될 것이다. 분산전원은 서로 다른 특징을 가지고 있고 또한 배전계통에서 기존의 계통운영과는 다른 형태로 운전될 것이다. 이런 관점에서 다수의 분산전원을 모아 하나의 가상의 발전소로 운영하는 개념이 등장하게 되었는데, 이를 Virtual Power Plant(VPP)라고 한다. VPP는 매니지먼트 시스템이 관리하는 여러 클러스터들로 이루어져 있으며 이들 클러스터들은 각각 여러 종류의 분산전원으로 구성되어 있다. 본 논문에서는 클러스터를 이루는 분산전원을 어떻게 운영하는 것이 최적의 경제적 효율을 지닐 수 있을 지에 대해 논의하게 될 것이다. 디젤 발전기의 출력의 경우 그 소유자에 의해 제어가 가능하지만, 태양광 발전 시스템의 경우 기상 상태에 따라 그 출력이 결정된다. 따라서 이러한 각각의 특성을 고려하여 본 논문에서는 디젤, CHP(Combined Heat and Power), 보일러, 태양광발전으로 구성된 복합 시스템에서 각 시간별로 수용가의 전력 및 열 수요와 분산전원의 에너지 생산을 비교하여 VPP 최적 운영 계획을 구성하였다.