• Journal of the Korea Institute of Military Science and Technology
• /
• v.14 no.6
• /
• pp.1178-1185
• /
• 2011

In the present study, a recuperator is suggested to improve the thermal efficiency of a micro gas turbine. Primary design parameters of the recuperator are determined from the ideal cycle analysis. The counter flow plate-fin heat exchanger with offset strip fins is chosen as the type of the recuperator. In order to satisfy the design constraints which are the minimum effectiveness and the maximum pressure drop, the optimization for the internal structure of the recuperator is performed with varying the fin spacing and the fin height of offset strip fins. Also the effects of the thermal conductivity of fins and separation plates and the longitudinal heat conduction on the thermal performance of the recuperator are investigated.

• 월간 기계설비
• /
• s.307
• /
• pp.87-92
• /
• 2016

대한기계설비산업연구원(원장 이언구)은 지난해 4월 연구심의위원회에서 선정된 ${\triangle}$기계설비건설업 동향분석 ${\triangle}$기계설비건설업체의 부도예측 모형 연구 ${\triangle}$기계설비건설공사 시공상세도면 작성비 산정기준 연구 ${\triangle}$플랜트 건설 현장 외국인력 고용 개선방안 ${\triangle}$녹색기술 기준에 근거한 연구과제 도출을 위한 기초연구 ${\triangle}$대용량 지열설비 이용을 위한 지중열교환기 용량 설계 툴 개발 ${\triangle}$기계설비배관 및 장비 단열 기준 연구 등의 기본과제와 외부기관과 공동으로 수행한 ${\triangle}$플랜트 건설현장 외국인력 고용 개선방안 ${\triangle}$기계설비건설업 관련법류 개선방안 연구를 추진했다. 본지는 연구결과에 대한 요약 보고서를 연재한다.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
• /
• v.18 no.2
• /
• pp.121-129
• /
• 1989

헬륨을 이용한 극저온 냉동기는 압축기(compressor)을 통하여 압력을 10-20 기압 정도로 높혀준후 여러 단계의 열교환기(heat exchanger)를 통하여 상전위온도(maximum inversion temperature) 이하로 떨어뜨린후 Joule-Thomson 밸브를 통하면 4K까지 온도가 떨어진다. 이때 압력은 1기압 정도이며 헬륨가스는 액체로 변한다. 본 연구의 목적은 Gifford-McMahon 냉동기와 Joule-Thomson 냉동기의 혼합형인 극저온 냉동기를 설계, 제작하여 죠셉슨(Josephson) 소자를 이용한 SQUID(초전도양자 간섭장치), 여러 종류의 탐지기, 컴퓨터 소자 개발 등을 위한 냉동기로 사용하는데 그 목적이 있다. 개발되는 법동기의 용량은 1 W이며, 최저온도는 4K 정도가 된다.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.16 no.1
• /
• pp.17-25
• /
• 2020

Ground-coupled heat pump (GCHP) systems have become an efficient alternative to conventional cooling and heating methods due to their higher energy using efficiency. Although some experimental and simulation works related to performance analysis of GCHP systems for commercial buildings have been done, relatively little has been reported on the performance evaluation of GCHP systems for school buildings. The purpose of this simulation study is to evaluate the performance of a hypothetical GCHP system for a school building in Seoul. We collected various data of building specifications and construction materials for the building and then modeled to calculate hourly building loads with SketchuUp and TRNSYS V17. In addition, we used GLD (Ground Loop Design) V2016, a GCHP system design and simulation software, to design the GCHP system for the building and to simulate temperature of circulating water in ground heat exchanger. The variation of entering source temperature (EST) into the system was calculated with different prediction time and then each result was compared. For 20 years of prediction time, EST for baseline design (Case A) based on the hourly simulation results were outranged from the design criteria.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.8 no.1
• /
• pp.89-99
• /
• 1999

The automatic design of shell & tube type oil cooler can be used in real industrial environments. Since the automatic design system is intended to be used in small companies, it is designed to be operated well under environments of CAD package in the personal computer. It has adopted GUI in design system, and has employed DCl language. Design parameters to be considered in the design stage of shell and tube type oil cooler are type of oil cooler, outer diameter, thickness, length of tube, tube arrangement, tube pitch, flow rate, inlet and outlet temperature, physical properties, premissive pressure loss on both sides, type of baffle plate, baffle plate cutting ratio, clearance between baffle plate outer diameter and shell inner diameter and clearance between baffle plate holes. As a result, the automatic design system of shell & tube type oil cooler is constructed by the environment of CAD software using LISP. We have built database of design data for various kinds of shell & tube type oil coolers. The automatic design system have been assessed and compared with existing specification of design. Good agreement with Handbook of heat exchanger and design dta of real industrial environments has been found.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.05a
• /
• pp.97.2-97.2
• /
• 2011

본 연구는 연료전지 중 용융탄산염을 전해질로 하는 MCFC의 MBOP에 포함된 부품으로 매우 중요한 역할을 하는 가습기와 이때 발생되는 폐열을 회수하기 위한 장치인 HRU에 관한 것이다. 가습기는 연료와 물이 가습기 상부로 유입되어 가습기 하부로 유입되는 배가스와 열교환을 하면서 물이 스팀화 되어 연료가 가습된 상태로 가습기 출구로 일정온도를 유지하며 배출된다. 또한 HRU는 가습기에서 배출된 고온의 배가스를 물을 이용하여 열교환을 통해서 열을 회수하여 난방 및 온수로 사용할 수 있는 열교환 장치를 말한다. 먼저 이들의 특성을 파악하기 위해 가습기 및 HRU를 설계, 제작하여 각각의 특성을 확인하였다. 가습기와 HRU의 성능 향상을 위해 먼저 열교환부에 적용될 튜브의 수치해석적 분석을 통해서 최적의 열전달 성능을 얻을 수 있는 가습기 및 HRU를 설계, 제작하였으며 이들의 성능을 파악하기 위해 120,000kcal/h 용량을 테스트 할 수 있는 장치를 구축하여, 이들의 열전달 특성, 압력강하, 회수 열량, 가습기 온도 등의 특성을 파악하였다. 이 장치를 통해서 확인된 가습기와 HRU의 특성은 수치해석을 통해서 얻은 값과 거의 유사함을 확인할 수 있었으며, 가습 성능도 효과적으로 달성할 수 있었다. 가습기와 HRU의 특성 중 압력강하 부분은 지속적인 연구가 필요한 부분이며, 가습기와 HRU의 일체화를 통하여 소형화 및 설치공간 축소 효과를 얻을 것으로 본다.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.8 no.6
• /
• pp.517-525
• /
• 1984

This paper presents a typical solar domestic hot water system and estimates their performances with variance of collector size, storage volume, collector tilt and other factors. The analysis is performed by th computer simulation for which conceptual system against 8760 hourly solar intensities and ambient temperature for a model year stored in the computer has been running. System performance is analyzed on hourly, monthly and yearly basis respectively and at the same time, the economics of various systems are evaluated. And also, this paper shows how an optimized design can be selected for any locality for which solar data and collector performance are provided. The results of this study are as follows. (1)Storage volume of 45 liter per square meter of solar collector lead to the best design. (2)Tilting the collectors to the same angle of the latitude is generally the best (3)Optimal size of collector is approximately 6.68-8.35m$^{2}$ when the latitude is 37.6 .deg. N and storage volume is 300 liter. (4)The performances of a solar domestic hot water system does not depend on the hourly usage but the daily usage.

• Journal of Energy Engineering
• /
• v.25 no.3
• /
• pp.59-65
• /
• 2016

MVR evaporation is a method of pressurizing the evaporating steam to raise its temperature with an electric compressor instead of burning fuel and reusing the heat source through the embraced heat exchanger to minimize energy use. MVR desalination system with wind power uses varying wind power instead of stable electricity and can flexibly control the volume of fresh water production. The present study introduces the design, construction and operation of a MVR desalination system of 30ton/day capacity. Experimental results, MVR compression ratio is higher than 1.5, temperature difference of the main heat exchanger is $5{\sim}7^{\circ}C$. This value shows the same performance as the designed value.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.34 no.5
• /
• pp.531-537
• /
• 2010

This paper optimized the design parameters of the offset strip fin in a heat exchanger. To decrease the pressure drop and increase heat transfer, the performance factors such as j/f, $j/f^{1/3}$, and JF, which could be used to estimate the pressure drop and heat transfer simultaneously, were employed as the criteria for optimization. In the present study, STDQAO, PQRSM, and MGA were used for solving the constrained nonlinear optimization problem. The JF factor and heat transfer performance of the optimized offset-strip fin were greater than those of the reference offset-strip fin by 36% and 280%, respectively.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.31 no.3 s.258
• /
• pp.256-263
• /
• 2007

The purpose of this study is to investigate the cooling performance of heat sinks for an electronic telecommunication system by adequate natural convection. Heat generation rates of electronic components and the temperature distributions of heat sinks and surrounding air are analyzed experimentally and numerically. In order to perform the heat transfer analysis for the thermal design of telecommunication system a program is developed. The program used the graphic user interface environment to determine the arrangement of heat sources, interior fan capacity, and heat sink configuration. The simulation results showed that the heat sinks were able to achieve a cooling capacity of up to 230W at the maximum temperature difference of $19^{\circ}C$. To verify the results from the numerical simulation, an experiment was conducted under the same condition as the numerical simulation, and their results were compared. The design program gave good prediction of the effects of various parameters involved in the design of a heat sinks for an electronic telecommunication system.