• 한국산업융합학회 논문집
• /
• 제26권2_2호
• /
• pp.255-263
• /
• 2023

The shell and tube-type heat exchangers have been frequently used in many industrial field because of its simple structure and wide operation conditions and so on. The purpose of this study is to investigate the flow characteristics in single shell of shell and tube-type heat exchanger according to velocity and temperature of hot air released from heat exchanger simulator through numerical analysis. As the results, the temperature was decreased in almost quadratic curve from top to bottom in single shell of the shell and tube-type heat exchanger. Further the changes of pressure and velocity in outlet according to change of inlet temperature were not observed. The cost for operating the shell and tube-type heat exchanger should be compared the supply cost of hot air with that of velocity in order to make a economic decision.

• 소음진동
• /
• 제5권4호
• /
• pp.515-524
• /
• 1995

Tubes in heat exchanger of fuel rods in reactor core are supported at intemediate point by support p0lates or springs. Current practice is, in case of heat exchanger, to allow clearance between tube and support plate for design and manufacturing consideration. And in case of fuel rod the clearance in support point can be generated due to the support spring force relaxation. Flow-induced vibration of a tube can cause it to impact or rub against support plate or against adjacent tubes and can result in fretting-wear. The tube-to- support dynamic interaction is used to relate experimental wear data from single-span test rigs to real multi-span heat exchanger configurations. The dynamic interaction cna be measured during experimental wear tests. However, the dynamic interaction is difficult to measure in real heat exchangers and, therefore, analytical techniques are required to estimate this interaction. This paper describels the nonlinear impact model of DAGS(Dynamic Analysis of Gapped Structure) code which simulates the tube response to external sinusodial or step excitation and predicts tube motion and tube-to-support dynamic interaction. Three experimental measurements-two single span rods excited by sinusodial force and a two span rod impacted by a steel ball are compared from the simulation nonlinear model of DAGS code. The simulation results from DAGS code are in good agreement with measurements. Therefore, the developed model of DAGS code is good analytical tool for estimating tube-to-support dynamic interaction in real heat exchangers.

• 한국압력기기공학회 논문집
• /
• 제5권1호
• /
• pp.1-8
• /
• 2009

본 논문에서는 국제적으로 개발 중인 초고온가스로와 연계하여 대량의 수소를 생산하기 위한 방안의 일환으로 국내에서 개발 중인 고온증기전기분해 시스템에 사용될 열교환기 재료의 고온증기 부식실험에 대해 소개하였다. 이를 위해 관련된 국내외 연구현황을 조사분석한 결과를 요약하여 소개하였으며 마지막으로 현재 수행중인 고온증기부식 연구의 실험조건 및 계획을 제시하였다. 실험 및 연구결과는 초고온가스로와 연계된 고온전기분해를 이용한 수소생산시스템의 개발에 활용될 예정이다.

• 설비공학논문집
• /
• 제10권6호
• /
• pp.773-783
• /
• 1998

The heating system for apartment complex may be classified as old systems including central system with steam boiler(S1), gas engine driven heat pump system(S2), system using waste heat(S3) and new systems including mechanical vapor re-compression system with flashing heat exchangers(S4), system using methanol(S5), system using metal hydride (S6). The purpose of the present study is to suggest optimal heating system by technically, economically and environmentally evaluating old and new heating systems of apartment complex from 500 to 3,000 households. Economic evaluation based on the technical evaluation results which estimated heat transfer area of heat exchangers and capacity of equipments was estimated initial investment cost, annual operating cost and relative payback period by considering annual increasing rates of energy cost and interest. Environmental evaluation provided annual generation rate of carbon dioxide. Initial investment cost was cheap in the order of S6, S5, S3, S2, S4, S1, annual operating cost was cheap in the order of S1, S2, S4, S5 and relative payback period was short in the order of S6, S5, S2, S3 and S4. Relative payback period was within 8 years for all scenarios of 3,000 households, and was increased as annual increasing rates of energy cost and interest were increased. As transportation pipe length was increased twice, payback period was increased by 1.4~2.6 time. The effect of temperatures of waste gas and waste water on the relative payback period was small within 0.8 years. The annual generation rate of carbon dioxide was big in the order of S4, S2 and S1. S4 was the most economic system among whole scenarios when S1 was replaced with other scenarios.

• 설비공학논문집
• /
• 제28권10호
• /
• pp.402-407
• /
• 2016

Ground-coupled heat pump systems have been widely used, as they are regarded as a renewable energy source and ensure a high annual efficiency. Among the system components, borehole heat exchangers (BHE) play an important role in decreasing the entering water temperature (EWT) to heat pumps in the cooling season, and consequently improve the COP. The optimal sizing of the BHEs is crucial for a successful project. Other than the existing sizing methods, a simulation-based design tool is more applicable for modern complex geothermal systems, and it may also be useful since design and engineering works operate on the same platform. A simulation-based sizing method is proposed in this study using the well-known Duct STorage (DST) model in Trnsys. TRNOPT, the Trnsys optimization tool, is used to search for an optimal value of the length of BHEs under given ground loads and ground properties. The result shows that a maximum EWT of BHEs during a design period (10 years) successfully approaches the design EWT while providing an optimal BHE length. Compared to the existing design tool, very similar lengths are calculated by both methods with a small error of 1.07%.

• 대한기계학회논문집B
• /
• 제41권9호
• /
• pp.587-595
• /
• 2017

최근 들어 공조기가 슬림화 되고 따라서 열교환기의 깊이를 줄일 필요가 있다. 본 연구에서는 슬림형 알루미늄 열교환기에 적절한 루버 핀 형상을 도출하였다. 또한 도출된 루버 핀이 적용된 알루미늄 열교환기 시료를 제작하고 성능 시험을 수행하였다. 비교를 위하여 기존 열교환기에 대해서도 실험을 수행하였다. 도출된 형상의 핀 깊이($F_d$)는 10.0 mm, 루버 핏치($L_p$)는 0.9 mm, 루버 각(${\theta}$)은 $35^{\circ}$이다. 기존 시료에 비하여 신규 슬림 시료의 j 인자는 36%, f 인자는 2.3% 크게 나타났다. 따라서 열교환기 체적은 슬림 시료에서 26% 줄어들게 된다. 또한 동일 소비 동력에서의 전열량을 의미하는 $j/f^{1/3}$은 슬림 시료에서 55% 크다. 실험 데이터를 기존 상관식의 예측치와 비교하였다.

• 한국수소및신에너지학회논문집
• /
• 제30권3호
• /
• pp.282-288
• /
• 2019

When liquefied natural gas (LNG) is vaporized to form natural gas for industrial and household consumption, a tremendous amount of cold energy is transferred from LNG to seawater as a part of the phase-change process. This heat exchange loop is not only a waste of cold energy, but causes thermal pollution to coastal fishery areas by dumping the cold energy into the sea. This project describes an innovative new design for reclaiming cold energy for use by cold storage warehouses (operating in the 35 to $62^{\circ}C$ range). Conventionally, warehouse cooling is done by mechanical refrigeration systems that consume large amounts of electricity for the maintenance of low temperatures. Here, a closed loop LNG heat exchange system was designed (by simulator) to replace mechanical or vapor-compression refrigeration systems. The software PRO II with PROVISION V9.4 was used to simulate LNG cold energy, gas re-liquefaction, and the vaporized process under various conditions. The effects on sensible and latent heats from changes to the array type of heat exchangers have been investigated, as well as an examination of the optimum.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2004년도 동계학술대회 논문집
• /
• pp.123-123
• /
• 2004

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2004년도 하계학술발표 논문집
• /
• pp.238-238
• /
• 2004

• 설비공학논문집
• /
• 제8권1호
• /
• pp.110-119
• /
• 1996

A numerical of thermoacoustic refrigerators has been developed. Effects of heat transfer and viscosity on pressure and velocity distributions in resonators and heat exchangers were considered. Predictions of cooling capacity and COP agreed well with previous experimental results. Effects of important design parameters, such as pressure ratio, spacing between the plates in the stack and stack length, on the performance of thermoacoustic refrigerators were shown.