• Journal of Advanced Marine Engineering and Technology
• /
• 제13권3호
• /
• pp.48-55
• /
• 1989

The purpose of present study is to evaluate both the radiative heat loss from a flame and the local formation and oxidation rate of soot. The present paper describes a comprehensive mathematical model to deal with combustion and radiative heat transfer simultaneously. The involved radiative heat transfer model was based on the "heat ray tracing method" originally proposed by Hayasaka et al.. Some predicted results were compared with the experiments.periments.

• 한국전산유체공학회지
• /
• 제13권2호
• /
• pp.68-72
• /
• 2008

NUFLEX is a general purpose thermo/fluid flow analysis program which has various physical models including spray. In NUFLEX, spray models are composed of breakup and collision models of droplet. However, in case of diesel engine, interaction between wall-film and impingement model considering heat transfer is not coded in NUFLEX. In this study, Lee & Ryou impingement & wall-film model considering heat transfer is applied to NUFLEX. For the verification of this NUFLEX program, numerical results are compared with experimental data. Differences of film thickness and radius between numerical results and experimental data are within 10% error range. The results show that NUFLEX can be used for comprehensive analysis of spray phenomena.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2008년도 춘계학술대회논문집
• /
• pp.71-74
• /
• 2008

NUFLEX is a general purpose thermo/fluid flow analysis program which has various physical models including spray. In NUFLEX, spray models are composed of breakup and collision models of droplet. However, in case of diesel engine, interaction between wall-film and impingement model considering heat transfer is not coded in NUFLEX. In this study, Lee & Ryou impingement & wall-film model considering heat transfer is applied to NUFLEX. For the verification of this NUFLEX program, numerical results are compared with experimental data. Differences of film thickness and radius between numerical results and experimental data are within 10% error range. The results show that NUFLEX can be used for comprehensive analysis of spray phenomena.

• 패션비즈니스
• /
• 제20권3호
• /
• pp.30-42
• /
• 2016

The objective of this study was to perform 3D solid modeling from 3D scanned surface images of cotton and silk in order to calculate the thermal heat transfer responses using numerical simulations. Continuing from the previous methodology, which provided 3D surface data for a fabric through optical measurements of the fabric microstructure, a simplified 3D solid model, containing a defined unit cell, pattern unit and fabric structure, was prepared. The loft method was used for 3D solid-model generation, and heat transfer calculations, made for the fabric, were then carried out using the 3D solid model. As a result, comprehensive protocols for 3D solid-model generation were established based on the optical measurements of real fabric samples. This method provides an effective means of using 3D information for building 3D models of actual fabrics and applying the model in numerical simulations. The developed process can be used as the basis for other analogous research areas to investigate the physical characteristics of any fabrics.

• 대한기계학회논문집B
• /
• 제26권6호
• /
• pp.883-892
• /
• 2002

A numerical study has been carried out to investigate the flow and heat transfer from an aluminum foam heat sink in a confined channel. A uniform heat flux is given at the bottom of the aluminum foam heat sink, which is horizontally placed on the heated surface. The channel walls are assumed to be adiabatic. Cold air is supplied from the top opening of the channel and exhausted to the channel outlet. Comprehensive numerical solutions are acquired to the governing Wavier-Stokes and energy equations, using the Brinkman-Forchheimer extended Darcy model and the local thermal non-equilibrium model f3r the region of porous media. Details of flow and thermal fields are examined over wide ranges of the principal parameters; i.e., the Reynolds number Re, the height of heat sink h/H, porosity $\varepsilon$and pore diameter ratio $R_{H}$.

• 대한기계학회논문집B
• /
• 제26권7호
• /
• pp.983-990
• /
• 2002

A numerical analysis has been carried out on forced convection heat transfer in the developing region of a porous channel. The channel is filled with an isotropic porous medium. At the channel walls, a uniform heat flux is given. Comprehensive numerical solutions are acquired to the Brinkman-Forchheimer extended Darcy equation and the LTNE model which does not employ the assumption of local thermal equilibrium between solid and fluid phases. Details of thermal fields in the developing region are examined over wide ranges of the thermal parameters. The numerical solutions at the fully developed region are compared with the previous analytical solutions. The correlation for predicting local Nusselt number in a porous channel is proposed.

• 한국가스학회지
• /
• 제27권3호
• /
• pp.123-133
• /
• 2023

상용 수소연료전지 차량은 기체 수소를 고압으로 압축하여 차량 내 저장 탱크로 저장하는 방식으로 충전이 진행된다. 이러한 압축 과정은 기체의 온도 상승을 유발하며, 저장 탱크의 안전성을 확보하기 위해 온도는 제한된다. 따라서 이러한 온도 상승을 설명하기 위한 열전달 모델이 필요하다. 열전달 모델은 대류 열전달 현상을 포함하며 정확한 대류 열전달 계수 추산이 요구된다. 본 연구에서는 수소 충전 과정에서의 대류 열전달 계수를 물리적 현상을 고려한 다양한 상관관계식을 이용하여 계산하고 비교 분석하였다. 수소 충전 과정은 디스펜서로부터 탱크 입구까지의 충전라인과 차량 내 저장 탱크로 분류하였고, 각각의 내부 및 외부에서의 대류 열전달 계수를 질량 유량, 직경, 온도와 압력 등 공정 변수에 따라 추산하였다. 그 결과, 충전라인 내부의 경우 저장 탱크 내부에서보다 대류 열전달 계수가 약 1000배 크게 나타났고, 충전라인 외부의 경우 저장 탱크 외부에서보다 대류 열전달 계수가 약 3배 크게 나타났다. 마지막으로 각 과정에서의 대류 열전달 계수를 종합 분석한 결과 전체 수소 충전 과정에서 저장 탱크 외부에서의 열전달 계수가 가장 낮아 열전달 현상을 지배하는 것으로 나타났다.

• 설비공학논문집
• /
• 제25권11호
• /
• pp.600-605
• /
• 2013

Ground source heat pump systems (GSHP) can achieve higher performance of the system, by supplying more efficient heat source to the heat pump, than the conventional air-source heat pump system. But building clients and designers have hesitated to use GSHP systems, due to expensive initial cost, and uncertain economic feasibility. In order to reduce the initial cost, many researches have focused on the energy-pile system, using the structure of the building as a heat exchanger. Even though several experimental studies for the energy-pile system have been conducted, there was not enough data of quantitative evaluation with economic analysis and comprehensive analysis for the energy-pile. In this study, a prediction method has been developed for the energy pile system with barrette pile, using the ground heat transfer model and ground heat exchanger model. Moreover, a feasibility study for the energy pile system with barrette pile was conducted, by performance analysis and LCC assessment. As a result, it was found that the heat exchange rate of a barrette pile was 2.55 kW, and the payback period using LCC analysis was 8.8 years.

• 대한조선학회논문집
• /
• 제41권6호
• /
• pp.134-139
• /
• 2004

It is known that over 60% of engine power is dissipated into circumstance, cooling water and cooling oil without any conversion into useful work. Following the first law of thermodynamics, it is possible that heat loss to cooling water can be converted into mechanical work through crankshaft. But in case that the engine is operating without any cooling effect, the serious problem unsolved so far is the engine durability. In this study, LHR(Low Heat Rejection) engine was introduced as one of the promising engine and several useful qualitative and quantitative data were drawn.

• 한국가시화정보학회지
• /
• 제14권2호
• /
• pp.52-60
• /
• 2016

The Passive Auxiliary Feedwater System(PAFS) is one of the advanced safety concepts adopted in the Advanced Power Reactor Plus(APR+). To validate the operational performance of the PAFS, detailed understanding of a boiling heat transfer on horizontal tube outside is of great importance. Especially, in the mechanistic boiling heat transfer model, it is important to visualize the phenomena but there are some limitations with conventional experimental approaches. In the present study, we devised a heater based on the Flexible Printed Circuit Board (FPCB) for a more comprehensive visualization and subsequently, a digital image processing technique for the bubble motion measurement was established. Using the measurement technique, important parameters of the nucleate boiling are analyzed.