• 대한기계학회논문집B
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• 제41권8호
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• pp.545-552
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• 2017

본 연구에서는 1 kW급 가정용 열병합 시스템의 원동기로 설계된 스털링 엔진의 고온 열교환기에 대하여 Fin 길이, 간격, 각도 등을 조정한 새로운 형상 및 기존 형상에 대하여 수치해석을 수행하여 형상 개선에 따른 성능 향상을 확인하였다. 형상을 개선하는 과정에서 고려하지 않았던 공기예열기를 포함하여 수치해석을 수행한 결과 실린더 헤드 부분에서 음의 열유속이 발생하는 현상이 관찰되었다. 배가스 온도 및 연소실 벽면 온도를 분석하여 이 현상을 규명하였다. 다음으로 이상적인 사이클을 가정하여 형상 개선에 의한 열전달량 증가가 열역학적 사이클 및 시스템 성능에 미치는 영향을 예측하였다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.1226-1231
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• 2009

This paper presents operating characteristics of internal heat exchanger(IHX) for $CO_2$ geothermal heat pump in the heating mode. Mass flow rate of $CO_2$, inlet temperatures of $CO_2$ at high and low pressure side were selected as main effect factors by using fractional factorial DOE(Design of Experiments). And RSM(Response Surface Method) was used in optimization phase. The results show that heat transfer rate of IHX increases when either inlet temperature of low pressure side decreases or inlet temperature of high pressure side increases. Effectiveness of IHX increases with increasing of inlet temperature of either high pressure side or low pressure side. Finally, performance contour map was provided over the operation ranges of the main design factors.

• 융합정보논문지
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• 제10권2호
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• pp.82-88
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• 2020

본 연구는 화공용 열교환기에서 법랑코팅 적용을 위한 고온의 소성 공정조건 최적화에 대한 기초자료를 얻고자 하는데 그 목적이 있다. Shell & Tube 형태인 열교환기에 법랑코팅 적용을 위해 소성온도를 순차적으로 높이는 방안에 대해 검토하였다. 소성로 내부에서 열교환기의 온도분포에 대해 CFD 상용 프로그램으로 수치계산하여 구한 온도를 하중조건으로 열응력 해석을 수행하는 연성 해석(FSI) 방식을 이용하여 열교환기의 구조 안전성에 미치는 영향을 확인하였다. 수치해석 및 실험결과 상온의 열교환기를 바로 860℃도의 소성로에 넣으면 열교환기의 국부적 온도차로 인한 구조 안전성에 문제가 발생하므로 온도차를 줄이기 위한 예열 과정이 필요하다. 소성공정 단계가 적은 Case2와 같이 1단계 예열온도 445℃, 2단계 소성온도 860℃가 가장 적합한 것으로 판단된다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.1294-1299
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• 2009

Since the operating pressure of $CO_2$ gascooler is so high compared with that of previous subcritical condenser, the optimization of gascooler is needed for improve heat exchanger performance. In this study, the performance characteristics of five kinds of heat exchangers were analyzed and compared with operating conditions. As a result, the 4-20 HX-tube shows the maximum gascooler capacity because the heat transfer is effective and pressure drop is small. Beside, the high performance of 4-20 HX-tube could be keep for wide operating condition.

• 소성∙가공
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• 제23권7호
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• pp.419-424
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• 2014

In order to improve efficiency, an outdoor unit using a refrigerant cooling method is designed into many air conditioner systems. The heat exchanger is composed of a Cu tube and an plate. The optimal design for the cold plate is very important because the efficiency of the heat transfer depends on the contact area between the Cu tube and the cold plate. The current study focused on the design of the cold plate to obtain a uniform contact between the Cu tube and the cold plate. Both FE(finite element) analysis and optimization were used in the design. The contact area between the tube and plate was predicted and improved by 16% through the press forming simulations. The springback after press forming was also reduced when the optimized design parameters were used. To verify the validity of the optimal cold plate design, a verification test was conducted. As a result, the performance of the heat exchanger improved by 34% when compared to benchmarked products.

• 한국군사과학기술학회지
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• 제14권6호
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• pp.1178-1185
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• 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.

• 대한기계학회논문집B
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• 제38권11호
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• pp.925-933
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• 2014

오늘날 고성능컴퓨터로 인해 많은 산업분야에서 전산해석이 사용되고 있다. 하지만 정해진 컴퓨터자원과 시간에 의해 3 차원 풀 스케일 해석에서는 많은 어려움 등이 있다. 본 연구에서 ${\varepsilon}-NTU$ 식과 열교환기 성능의 데이터베이스를 이용해 열교환기의 성능예측프로그램을 개발하였다. 다양한 타입의 열교환기 형상정보와 성능데이터베이스를 구축하였고, 이를 바탕으로 정해진 작동 조건에서 열교환기의 성능을 계산하였다. 계산된 정보를 바탕으로 최적의 사이즈를 갖는 형상을 찾기 위해 유전알고리즘(Genetic Algorithm)을 이용하였다. 계산을 위해 상용 소프트웨어인 MATLAB 과 REFPROP 이 사용되었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1053-1057
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• 2004

This paper presents the adjoint variable design sensitivity analysis for thermal systems considering both conduction and convection heat transfer. Both nodal temperature and total heat flow are considered to be objective functions and design sensitivity formulas are derived for each case. For the case of convection heat transfer, the adjoint analysis is carefully proceeded to obtain a precise result. A topology optimization example is examined for a simple planar square plate in order to design a heat exchanger as verification.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1022-1027
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• 2004

In this study, the shape of plate-fin type heat sink is numerically optimized to acquire the minimum pressure drop under the required temperature rise. To do this, a new sequential approximate optimization (SAO) is proposed and it is integrated with the computational fluid dynamics (CFD). In thermal/fluid systems for constrained nonlinear optimization problems, three fundamental difficulties such as high cost for function evaluations (i.e., pressure drop and thermal resistance), the absence of design sensitivity information, and the occurrence of numerical noise are confronted. To overcome these problems, the progressive quadratic response surface method (PQRSM), which is one of the sequential approximate optimization algorithms, is proposed and the heat sink is optimize by means of the PQRSM.

• 설비공학논문집
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• 제19권7호
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• pp.500-511
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• 2007

The Optimal solutions of the design variables in internally finned tubes have been obtained for three-dimensional periodically fully developed turbulent flow and heat transfer. For a trapezoidal fin profile, performances of the heat exchanger are determined by considering the heat transfer rate and pressure drop, simultaneously, that are interdependent quantities. Therefore, Pareto frontier sets of a heat exchanger can be acquired by integrating CFD and a multi-objective optimization technique. The optimal values of fin widths $(d_1,\;d_2)$, fin height(h) and helix angle$(\gamma)$ are numerical1y obtained by minimizing the pressure loss and maximizing the heat transfer rate within ranges of $d_1=0.5\sim1.5mm$, $d_2=0.5\sim1.5mm$, $h=0.5\sim1.5mm$, and $\gamma=0\sim20^{\circ}$. For this, a general CFD code and a global genetic algorithm(GA) are used. The Pareto sets of the optimal solutions can be acquired after $30^{th}$ generation.