• Nuclear Engineering and Technology
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• 제54권7호
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• pp.2728-2735
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• 2022

The research on the flow and heat transfer characteristics of lead bismuth(LBE) is significant for the thermal-hydraulic calculation, safety analysis and practical application of lead-based fast reactors(LFR). In this paper, a new CFD model is proposed to solve the thermal-hydraulic analysis of LBE. The model includes two parts: turbulent model and turbulent Prandtl, which are the important factors for LBE. In order to find the best model, the experiment data and design of 19-pin hexagonal rod bundle with spacer grid, undertaken at the Karlsruhe Liquid Metal Laboratory (KALLA) are used for CFD calculation. Furthermore, the turbulent model includes SST k - 𝜔 and k - 𝜀; the turbulent Prandtl includes Cheng-Tak and constant (Pr_t =1.5,2.0,2.5,3.0). Among them, the combination between SST k - 𝜔 and Cheng-Tak is more suitable for the experiment. But in the low Pe region, the deviation between the experiment data and CFD result is too much. The reason may be the inlet-effect and when Pe is in a low level, the number of molecular thermal diffusion occupies an absolute advantage, and the buoyancy will enhance. In order to test and verify versatility of the model, the NCCL performed by the Nuclear Thermal-hydraulic Laboratory (Nuthel) of Xi'an Jiao tong University is used for CFD to calculate. This paper provides two verification examples for the new universal model.

• Nuclear Engineering and Technology
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• 제53권12호
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• pp.3910-3917
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• 2021

Reactor fuel's power distribution plays a vital role in designing the new generation thermionic Space Reactor Power Systems (SRPS). In this paper, the 1/12th SPACE-R's full reactor core was numerically analyzed with two kinds of different axial power distribution, to identify their impacts on thermal-hydraulic and thermoelectric characteristics. In the benchmark study, the maximum error between numerical results and existing data or design values ranged from 0.2 to 2.2%. Four main conclusions were obtained in the numerical analysis: a) The axial power distribution has less impact on coolant temperature. b) Axial power distribution influenced the emitter temperature distribution a lot, when the core power was cosine distributed, the maximum temperature of the emitter was 194 K higher than that of the uniform power distribution. c) Comparing to the cosine axial power distribution, the uniform axial power distribution would make the maximum temperature in each component of the reactor core much lower, reducing the requirements for core fuel material. d) Voltage and current distribution were similar to the axial electrode temperature distribution, and the axial power distribution has little effect on the output power.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2003년도 학술대회 논문집
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• pp.167-170
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• 2003

The thermal and hydraulic characteristics of the cooling passage for HTS power cable should be carefully investigated to get the highly reliable and economic operation. In this study, the pressure drop and temperature change of the coolant flowing the corrugated passage was estimated using the simple one-dimensional approach, and the temperature distribution in the radial direction was calculated. The results show the dependency of the mass flow rate, thermal conductivities on the cooling performance of the HTS cable.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2380-2382
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• 1999

An Ampacity of a power cable depends on the soil thermal property, especially the soil thermal resistivity. Also, The soil thermal resistivity depends on the soil moisture contents in soil surrounding the power cable. This paper propose the prediction algorithm of the soil moisture contents using the Thornthwaite theory.

• International Journal of Precision Engineering and Manufacturing
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• 제2권3호
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• pp.61-68
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• 2001

A linear motor has a lot of advantages in comparison with conventional feed mechanisms: high transitional speed, acceleration, high control performance and good positioning at high speed. Through the omission of a power transfer element, the linear motor shows no wear and no backlash, has along lifetime and is easy to assemble. Recently, the two types of linear motors, asynchronous and synchronous linear motors, are often applied to machine tools as a fast feed mechanism. In this paper, a comparison between the two types of linear motors as to power loss and thermal behavior is made. The heat sources of the linear motor-the electrical power loss in the motor and the frictional heat on the linear guidance-are measured and compared. Also, the temperature on the linear motor and machine structure is measured and presented.

• Journal of Welding and Joining
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• 제23권1호
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• pp.61-68
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• 2005

An analytical method for determining the thermal stress distributions in a 3-layered beam is developed, which is focused on the end effects. This method gives the stress distributions which satisfy the stress-free boundary condition at the end completely. For verification of the method, a numerical example which was introduced by other researchers is treated. The stress distributions agree with the results of other researchers. The results show that the show and peeling stresses at the interfaces are significant near the edge and become negligible in the interior region.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 추계학술대회
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• pp.45-46
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• 2017

The operating characteristics of power MOSFETs greatly vary depending on the junction temperature. A PSpice thermal model is implemented to simulate the temperature characteristics of the power MOSFETs in this paper. A thermal model is derived that can be applied online in PSpice simulations and PSpice parameters are reconstructed using a curve fitting from commercial data sheets. The implemented PSpice model is applied to the buck converter and the validity of the model is verified through experiments.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2007년도 춘계학술대회 논문집
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• pp.417-420
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• 2007

1997년 교토 기후협약이 체결되었고, 우리나라도 2013 년부터 기후협약 규제가 거의 확실시 되고 있다. 화석 연료의 연소로 대부분의 전력 을 생산하는 발전 산업은 우리나라 CO2 배출량의 25%를 차지하고 있으며, 발전소의 전력 생산에 따른 CO2배출량의 계산은 매우 중요한 일이 되었다. 본 논문은 발전소의 시험data 와 IPCC (Intergovernmental Panel on Climate Change)의 온실가스 추계방법론을 이용하여 시간당 CO2 대기 배출량을 계산하는 방법을 제시한다. 발전출력에 대한 CO2 배출량을 계산하는 한 예를 도시하였다.

• 한국경영과학회지
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• 제15권1호
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• pp.99-115
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• 1990

This paper is concerned with the unit commitment problem in an electric power system with both thermal and pumped-storage hydroelectric units. This is a mixed integer programming problem and the Lagrangean relaxation method is used. We show that the relaxed problem decomposes into two kinds of subproblems : a shortest-path problem for each thermal unit and a minimum cost flow problem for each pumped-storage hydroelectric unit. A method of obtaining an incumbenet solution from the solution of a relaxed problem is presented. The Lagrangean multipliers are updated using both subgradient and incremental cost. The algorithm is applied to a real Korean power generation system and its computational results are reported and compaired with other works.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 심포지엄 논문집 정보 및 제어부문
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• pp.240-242
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• 2006

The inspection method, which is used to inspect the electronic system for the control system of the fossil-powered thermal power plant, has the technical restrictions based on its primary application area, whereas the reliability is requested more and more by the plant operators to minimize the shutdown of a plant. This paper reviews the inspection methods currently used by the thermal power plant and how to adopt the condition based maintenance to increase the availability of power plant.