• 한국연소학회지
• /
• 제10권2호
• /
• pp.18-25
• /
• 2005

An experimental study has been conducted to evaluate the effects of reburning on $NO_x$ reduction and also to examine heat transfer characteristics from LPG flame. Experiments were performed in flames stabilized by a co-flow swirl burner, which was mounted at the bottom of the furnace. Tests were conducted using LPG gas as main fuel and also as reburn fuel. The effects of reburn fuel fraction and injecting location of reburn fuel are studied. The paper reports data on flue gas emissions, temperature distribution in furnace and various heat fluxes at the wall for a wide range of experimental conditions. In a steady state, the total as well as radiative heat flux from the flame to the wall of furnace has been measured using a heat flux meter. Temperature distribution and emission formation in furnace have been also measured and compared.

• 한국수소및신에너지학회논문집
• /
• 제26권2호
• /
• pp.127-135
• /
• 2015

High-Temperautre Polymer Electrolyte Membrane Fuel Cell (HT-PEMFC) with phosphoric acid-doped polybenzimidazole (PBI) membrane has high power density because of high operating temperature from 100 to $200^{\circ}C$. In fuel cell stack, heat is generated by electrochemical reaction and high operating temperature makes a lot of heat. This heat is caouse of durability and performance decrease about stack. For these reasons, heat management is important in HT-PEMFC. So, we developed HT-PEMFC model and study heat flow in HT-PEMFC stack. In this study, we placed coolant plate number per cell number ratio as variable and analysed heat flow distribution in stack.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1997년도 춘계학술대회 논문집
• /
• pp.799-804
• /
• 1997

This paper is concerned with the heat flux distribution and energy partition for creep-feed grinding. Form measurements of transient grinding temperatures in the workpiece sub-surface using an embeded thermocouple, the overall energy partition to the workpiece was estimated form moving heat source theory for a triangular heat flux distribution as 3.0% for down grinding and 4.5% for up grinding. The higher energy partition for up grinding can be attributed to the need to satisfy thermal compatibility at the grinding zone. The influence of cooling outside the grinding zone can be analytically taken into account by specifying convective heat transfer coefficients on the workpiecs surface h /sab a/ heat source (grinding zone) and h /sab b/ behind the heat source. The smaller energy patition together with slightly lower grinding power favors down grinding over up grinding.

• 설비공학논문집
• /
• 제26권4호
• /
• pp.193-198
• /
• 2014

Heat transfer performance variation of a condenser caused by non-uniform distribution of air flow was investigated using a numerical simulation method. A heat exchanger used for a outdoor unit of a commercial heat pump system and represented by a numerical model was selected. Non-uniform profile of air-velocity was constructed by measuring the air velocity at various locations of the outdoor unit. Simulation was conducted for various refrigerant circuits and air flow conditions. Simulation results show that the heat transfer capacity was reduced depending on the air-flow rate and the refrigerant circuit configuration. It is also shown that the capacity reduction rate is increased as the average air velocity decreases.

• 대한기계학회논문집A
• /
• 제20권12호
• /
• pp.3856-3870
• /
• 1996

The objective of this study is to evaluate heat transfer coefficient distribution during heat treatment by inverse analysis. As a first procedure, the inverse heat transfer formulation by using two dimensional finite element method has been developed. The formulation can handlematerial nonlinearity and allow arbitrary placement and number of sensors. The formulation was verified through application to simulated exact and inexact measurements.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2006년도 추계학술대회
• /
• pp.40-43
• /
• 2006

Public demand for the heat pump system as a next generation energy equipment is increasing for its eco-friendly and cost-effective advantage. Many researches have been concentrated on how to calculate and develop its own efficiency, while the possible effect of the heat pump operation on the whole subsurface temperature distribution is relatively less considered, During the current study, subsurface temperature disturbance caused by seasonal surface temperature cycle in Busan area and general W-tube heat pump operation is simulated in 3-dimensional heterogeneous medium. It shows that subsurface deeper than 10m from the surface remains nearly unchanged throughout the 4 seasons and groundwater convect ion in highly permeable layer near the surface acts like a main path of heat plume from heat pump system, This implies the significance of detail descript ion in shallow sedimentary layer or highly permeable layer which plays an important role on the regional flow advection and heat transfer. Also, the effect of groundwater convection increases when the arrangement of the 2 injection pipes and 2 extract ion well is maintained parallel to groundwater flow. Therefore, more careful and detail investigation is required before installation and operation of heat pump system that it may not cause any possible change of microbial ecosystem in the shallow subsurface environment or 'contamination of temperature' for groundwater use as well as the loss of efficiency of the equipment itself. This can also help to design the optimized grouting system for heat pump.

• 대한지리학회지
• /
• 제42권3호
• /
• pp.332-343
• /
• 2007

본 연구에서는 우리나라 열파의 지역별 분포를 파악하고 그 원인을 분석하고자 하였다. 이를 위해 $1973\sim2005$년 $5\sim9$월까지 60개 기상관측지점의 일최고기온과 수증기압, 상층의 바람 자료 등을 사용하여 일최고기온 상위 5% 이상인 날이 3일 이상 지속되는 현상을 열파로 정의하고, 열파일수의 분포와 그 원인을 분석하였다. 우리나라 열파일수는 충청 내륙 및 충청 서해안, 전라 내륙, 경상 내륙, 제주도 남부 지역에서 160일 이상으로 많고 동해안 중부와 제주도 북부 지역에서 110일 이하로 적다. 충청 내륙 및 충청 서해안과 전라 내륙 지역은 열파 발생 시 남서기류의 영향이 크므로 열파가 장기간 지속된다. 경상 내륙 지역은 남서기류에 소백산맥의 지형 효과가 결합되어 고온 건조해진 공기가 분지 지형 때문에 정체되고 지속적인 남서기류의 유입으로 인해 기온 편차가 큰 열파가 장기간 지속된다. 동해안 중부 지역은 태백산맥이 남서기류를 차단하기 때문에 열파일수가 적으나 일단 열파가 발생하면 푄 효과가 결합되어 기온 편차가 크다.

• 한국안전학회지
• /
• 제14권3호
• /
• pp.33-39
• /
• 1999

In a compartment fire with openings, convective heat transfer consists of natural convection from the hot bodies and forced convection by airflow through the openings. The same finite volume method that was applied to pure natural convection in part I was utilized without modification to the square cavity with two openings. The objective of this study is to investigate effects of the openings on temperature distribution. Flow patterns, temperature distribution and heat transfer were compared for different Rayleigh numbers and with and without the openings.

• Structural Engineering and Mechanics
• /
• 제56권3호
• /
• pp.341-354
• /
• 2015

The dual-phase lag heat transfer model is employed to study the problem of isotropic generalized thermoelastic medium with internal heat source. The normal mode analysis is used to obtain the exact expressions for displacement components, force stress and temperature distribution. The variations of the considered variables through the horizontal distance are illustrated graphically. The results are discussed and depicted graphically.

• 대한기계학회논문집B
• /
• 제25권11호
• /
• pp.1492-1499
• /
• 2001

In order to develop the compact and flexible heat exchangers, we made the helically coiled heat exchangers. They can be manufactured with small diameter copper tubes without the need for fins; inner diameter=1.0 mm, straight tube length=1.5 m. The experiments were carried out with the following conditions; evaporation pressure=0.6 MPa, air velocity=0.7 ∼ 1.7 m/s, and working fluid=R-22. Pressure drop and heat transfer coefficient of heat exchangers were experimented according to the air velocity. The results of heat transfer coefficient show a 35% beneficial increase fur these heat exchangers over the other covered fin-tube heat exchangers. A cooling capacity of about 3 kW was obtained with an air velocity of 1.5 m/s. The distribution header has also been designed fur efficient distribution of refrigerant flow.