• 제목/요약/키워드: Heat Transfer Experiment

검색결과 742건 처리시간 0.029초

직관 마이크로채널 PCHE의 열전달특성 및 압력강하 (Heat Transfer Characteristics and Pressure Drop in Straight Microchannel of the Printed Circuit Heat Exchangers)

  • 김윤호;문정은;최영종;이규정
    • 대한기계학회논문집B
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    • 제32권12호
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    • pp.915-923
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    • 2008
  • The performance experiments for a microchannel printed circuit heat exchanger (PCHE) of high-performance and high-efficiency on the two technologies of micro photo-etching and diffusion bonding were performed in this study. The microchannel PCHE were experimentally investigated for Reynolds number in ranges of 100 $\sim$ 700 under various flow conditions in the hot side and the cold side. The inlet temperatures of the hot side were conducted in range of $40^{\circ}C\;{\sim}\;50^{\circ}C$ while that of the cold-side were fixed at $20^{\circ}C$. In the flow pattern, the counter flow was provided 6.8% and 10 $\sim$ 15% higher average heat transfer rate and heat transfer performance than the parallel flow, respectively. The average heat transfer rate, heat transfer performance and pressure drop increases with increasing Reynolds number in all the experiment. The increasing of inlet temperature in the experiment range has not an effect on the heat transfer performance while the pressure drop decrease slightly with that of inlet temperature. The experimental correlations to the heat transfer coefficient and pressure drop factor as a function of the Reynolds number have been suggested for the microchannel PCHE.

충돌판(衝突板) 근방(近傍)에 배열(配列)된 2차원(次元) rod가 충돌분류(衝突噴流) 열전달(熱傳達)에 미치는 영향(影響)[3] : rod직경변화(直徑燮化)에 대한효과(效果) (Heat Transfer Augmentation on Flat Plate with Two-Dimensional Rods in Impinging Air Jet System [3] : Effect of Rod Diameter)

  • 김동춘;이용화;서정윤
    • 설비공학논문집
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    • 제2권4호
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    • pp.295-302
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    • 1990
  • The purpose of this study is augmentation of heat transfer without additional power in two-dimensional impinging air jet. The technique of heat transfer augmentation used in this experiment is to place rod bundles in front of the flat heated surface. The effects of rod diameter, nozzle-to-target plate distance and the nozzle exit velocity on heat transfer have been investigated. The main conclusions obtained from this experiment are as follows. High heat transfer augmentation is achieved by means of flow acceleration and thinning of boundary layer by placing rod bundles in front of the flat plate. Average heat transfer coefficient becomes maximum in the case of H/B=10,D=4mm. For H/B=2,D=4mm, maximum heat transfer augmentation has been determined to be about 1.5 times larger than that of the flat plate. Heat transfer augmentation by placing the rod bundles at 12m/s is to be about 2 times more than increasing nozzle exit velocity from 12m/s to 18m/s.

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비이온계 계면활성제 첨가수에 대한 관내 유동저항 감소 및 열전달 촉진에 관한 연구 (A Study on the Drag Reduction Effect and Heat Transfer Enhancement of Non ionized Surfactant and Water Mixture in a Circular Pipe Flow)

  • 김명준
    • Journal of Advanced Marine Engineering and Technology
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    • 제31권5호
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    • pp.552-557
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    • 2007
  • This paper has dealt with the effect of non ionized surfactant and water mixture on drag reduction and heat transfer enhancement in a circular pipe flow with experimentally. The test section was consisted of stainless steel pipe with inside diameter of 16mm. The wire coil was used to increase heat transfer in a pipe and the on ionized surfactant(Oleyl Dihydroxyethyl Amino Oxide, ODEAO) was used to reduce the drag force of water mixture with surfactant. The main parameters of this experiment were diameter and pitch of wire coil and the ratio of test section length and horizontal wire coil length. In this experiment, the acquired results were 1) Drag reduction effect existed in this ODEAO-water mixture, 2) Friction factor and heat transfer were increased with insertion the heat transfer enhancement coil, 3) With increasing of pitch ratio, heat transfer was decreased, and 4) Heat transfer was decreased by the decreasing of inserting coil diameter.

흡수식 냉온수기용 증발기의 전열성능에 관한 연구 (A study on the heat transfer performance of evaporator for absorption chiller)

  • 권오경;차동안;윤재호;김효상
    • 대한설비공학회:학술대회논문집
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    • 대한설비공학회 2008년도 동계학술발표대회 논문집
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    • pp.192-197
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    • 2008
  • The objectives of this paper are to measure the heat transfer and pressure drop of the heat transfer tube for an evaporator of absorption system applications. Five types of heat transfer tubes with different shape and heat transfer area are tested in the present experiment. Heat transfer and pressure drop performance of heat transfer tubes are measured in various operating conditions, and compared each other. The results show that the heat transfer rate of thermoexcel notch tube and low fin tube increases about 27.6% and 11.6% at the refrigerant flow rate 250 kg/h compared with that of bare tube, respectively. The thermoexcel notch tube is shown the best performance considering pressure drop and heat transfer coefficient.

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발포 금속을 사용하는 채널의 열전달 특성 실험 및 해석 (Experiment and Analysis on the Heat Transfer Characteristics of a Channel Filled with Metal Form)

  • 손영석;신지영;조영일
    • 설비공학논문집
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    • 제22권7호
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    • pp.448-453
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    • 2010
  • Porous media containing complex fluid passage have especially large surface area per unit volume. This study is aimed to identify the heat transfer characteristics of high-porosity metal foams in a horizontal channel. Experiment is performed under various heat flux, velocity and pore density. Nusselt number decreases with higher pore density. Metal foams shows higher heat transfer coefficients than pin-fin structure with the same porosity. This is due to the more complex flow passage and larger heat transfer area based on the structure of the metal foams. The analysis on the pin-fin structure may not be suitable to the metal foam structure but should be identified extensively through further study.

열전달과 물질전달의 유사성에 관한 연구 (A study on the Analogy between Heat Transfer and Mass Transfer)

  • 유성연;노종광;정문기
    • 대한기계학회논문집
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    • 제17권10호
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    • pp.2624-2633
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    • 1993
  • Mass transfer experiment by naphthalene sublimation method has great advantages in measurement of local transfer coefficients in the region of a three dimensional flow or for a model of complex geometry, which is considered to be very difficult with conventional heat transfer measurements. Mass transfer data obtained by naphthalene sublimation technique are converted to the heat transfer data through heat/mass transfer analogy. This analogy is valid for a simple or laminar flow, but new insight is needed when applying to a turbulent flow or complex flow such as separation, reattachment and recirculation, The purpose of this research is to investigate how geometries and flow conditions incorporate heat/mass transfer analogy. Mass transfer experiments are performed using naphthalene sublimation technique for a flat plate, a circular cylinder, and rectangular cylinders. And mass transfer data are compared with earlier heat transfer measurements for the same geometries. Usefulness of analogy relation between heat and mass transfer is examined with these results.

신형 알루미늄관의 열전달 특성에 관한 실험적 연구 (Experimental study on the characteristics of heat transfer for new type aluminum tube)

  • 문춘근;윤정인;김재돌
    • Journal of Advanced Marine Engineering and Technology
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    • 제24권2호
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    • pp.31-37
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    • 2000
  • This study investigated heat transfer characteristics of refrigeration system using new type aluminium heat transfer tube for evaporator of refrigeration and air-conditioning comparing with bare tube. From the result of heat transfer experiment form one phase flow using cooled and hot water, about 20% heat transfer performance is superior in case of same quantity of flow and about 4% heat transfer performance if superior in case of same velocity comparing with bare tube. Casing of two phase flow, heat transfer performance of new type aluminum heat transfer tube shows about 50% superior heat transfer performance comparing with bare tube in the same evaporating pressure when using heat transfer tube as evaporator and shows about 47% increase when expressing performance coefficient as the rate of refrigerating capacity and compressing work. However, it can be known that pressure drop in the heat transfer tube is taken higher value of about 18% in case of new type aluminum heat transfer tube. From the above result, new type aluminum heat transfer tube is excellent comparing with bare heat transfer tube using the existing heat exchanger for refrigerator.

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Wilson plot법을 이용한 Plate & Shell 열교환기의 단상유동 열전달 특성에 관한 실험적 연구 (Experimental Study on Heat Transfer Characteristics for Single-phase Flow in Plate & Shell Heat Exchangers by Using Wilson Plot Method)

  • 서무교;김영수;이상경
    • 동력기계공학회지
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    • 제3권4호
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    • pp.22-27
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    • 1999
  • Single phase heat transfer coefficients were measured for turbulent water flow in a plate & shell heat exchangers by using Wilson plot method. An experiment for counterflow heat exchange between the plate and shell was performed. The shell side heat transfer resistance was varied and the overall heat transfer coefficients were measured. The single-phase heat transfer coefficients in a plate side were obtained by Wilson plot method. Single-phase heat transfer correlations based on projected heat transfer area have been proposed for a plate & shell heat exchanger.

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최적화 기법을 활용한 열전달계수의 측정 (A study on the Evaluation of Heat Transfer Coefficient by Optimization Algorithm)

  • 김정태;임채호;최정길
    • 소성∙가공
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    • 제15권9호
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    • pp.679-685
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    • 2006
  • New method for evaluation of heat transfer coefficient is proposed. In general, many researchers have been studied about inverse problem in order to calculate the heat transfer coefficient on three-dimensional heat conduction problem. But they can get the time-dependent heat transfer coefficient only through inverse problem. In order to acquire temperature-dependent heat transfer coefficient, it requires much time for numerous repetitive calculation and inconvenient manual modification. In order to solve these problems, we are using the SQP(Sequential Quadratic Programming) as an optimization algorithm. When the temperature history is given by experiment, the optimization algorithm can evaluate the temperature-dependent heat transfer coefficient with automatic repetitive calculation until difference between calculated temperature history and experimental ones is minimized. Finally, temperature-dependent heat transfer coefficient evaluated by developed program can used on various heat transfer problem.

원형휜-원형관 열교환기의 휜효율 이론에 관한 수치적 검증 (VERIFICATION OF FIN EFFICIENCY THEORY FOR THE CIRCULAR FINNED-TUBE HEAT EXCHANGER BY NUMERICAL EXPERIMENT)

  • 강희찬;임복빈;이종휘;장병춘;안서욱
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 2008년도 학술대회
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    • pp.137-142
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    • 2008
  • The purpose of the present study is to investigate the convective heat transfer characteristics and the validity of fin efficiency of the circular finned-tube heat exchanger by using commercial CFD code. The heat transfer coefficient obtained by using the laminar model was 22% overestimated to the experimental data. The fin surface temperature compared with the experimental data measured by the liquid crystal method. The fin efficiency by the present numerical experiment, defined as normalized and averaged fin surface temperature, was greater than the theoretical fin efficiency and the difference is increased at high value of the factor m.

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