• 제목/요약/키워드: Colburn j계수

검색결과 22건 처리시간 0.03초

세관내 액단상의 열전달과 압력강하에 관한 연구 (The Heat Transfer and Pressure drop Characteristics of R7l8 in Small Diameter Tubes)

  • 김세웅;홍진우;손창효;노건상;오후규
    • 한국마린엔지니어링학회:학술대회논문집
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    • 한국마린엔지니어링학회 2001년도 추계학술대회 논문집(Proceeding of the KOSME 2001 Autumn Annual Meeting)
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    • pp.28-35
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    • 2001
  • The heat transfer and pressure drop characteristics of R718 flowing in smooth horizontal copper tubes with inner diameter of 3.36 mm, 5.35 mm, 6.54 mm and 8.12 mm were investigated. The test section is a counterflow heat exchanger with refrigerant flowing in the inner tube and water flowing in the annulus. Experiments were peformed for the flowing range of variables : Reynolds number (1000 to 20000), mass flow rate of brine (450 kg/h) and refrigerant temperature (5$0^{\circ}C$). The main results were summarized as follows : (1) The heat transfer coefficient of 3.36 mm ID was about 10% to 30% higher than that of 5.35 mm, 6.54 mm and 8.12 mm ID, and the heat transfer coefficients for small diameter. tubes are about 20% to 27% higher than these predicted by Gnielinski. The new correlation is proposed to predict the experimental data. (2) As a result of comparison with correlation prosed by Blasius. the deviation of the experimental data slightly increased as the tube diameter decreased. (3) The ratio of heat transfer to friction factor (j/f) correlated by all experimental data increased as the tube diameter decreased.

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증발기의 설계조건에서 공기측 열전달계수 및 압력강하 산출 (Evaluation of Air-side Heat Transfer and Friction Characteristics on Design Conditions of Evaporator)

  • 김창덕;이진호
    • 설비공학논문집
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    • 제15권12호
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    • pp.1007-1017
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    • 2003
  • An experimental study on the air-side pressure drop and heat transfer coefficient of slit fin-tube heat exchanger has been carried out. The data reduction methodology for air-side heat transfer coefficients in the literature is not based on a consistent approach. This paper focuses on new method of data reduction to obtain the air-side performance of fin-tube heat exchanger using R22 and recommends standard procedures for dry and wet surface heat transfer estimation in fin-tube heat exchanger having refrigerant on the tube-side. Results are presented as plots of friction f-factor and Colburn j -factor against Reynolds number based on the fin collar outside diameter and compared with previous studies. The data covers a range of refrigerant mass fluxes of 150∼250 kg/$m^2$s with air flows at velocity ranges from 0.3 m/s to 0.8 m/s.

응축기의 설계조건에서 공기측 열전달계수 및 압력강하 산출 (Evaluation of Air-side Heat Transfer and Friction Characteristics on Design Conditions of Condenser)

  • 김창덕;전창덕;이진호
    • 설비공학논문집
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    • 제15권3호
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    • pp.220-229
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    • 2003
  • An experimental study on the air-side pressure drop and heat transfer coefficient of slit fin-tube heat exchanger has been carried out. The data reduction methodology for air-side heat transfer coefficients in the literature is not based on a consistent approach. This paper focuses on new method of data reduction to obtain the air-side performance of fin-tube heat exchanger using R22 and recommends standard procedures for dry surface heat transfer estimation in fin-tube heat exchanger having refrigerant on the tube-side. Results are presented as plots of friction f-factor and Colburn j -factor against Reynolds number based on the fin collar outside diameter and compared with previous studies. The data covers a range of refrigerant mass fluxes of 150~250 kg/$m^2$s with air flows at velocity ranges from 0.6 m/s to 1.6 m/s.

입구영향 및 주름높이의 변화를 고려한 판형열교환기의 유동 및 열전달 특성 (Investigation of Flow and Heat Transfer Characteristics of Plate Heat Exchanger Taking into Account Entrance Effects and Variation in Corrugation Height)

  • 모정하
    • 대한기계학회논문집B
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    • 제34권11호
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    • pp.965-973
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    • 2010
  • 본 연구에서는 입구영향과 주름높이가 고려된 판형열교환기의 유동 및 열전달특성을 수치적으로 해석하였다. 여러 개의 단위셀을 연결한 다중셀에 입구부와 출구부가 부착된 모델을 기본으로 입구부의 길이변화($L_{cell}{\sim}5L_{cell}$)에 따른 모델과 P/H비 변화($2{\leq}P/H{\leq}4$)에 따른 모델에 대하여 수치해석을 수행하였다. 수치조건은 쉐브론각 $15^{\circ}$, 주름피치 24mm이며, $1,000{\leq}Re{\leq}10,000$이다. 마찰인자는f=$CRe^m$의 형태로, Colburn j 계수는 j=$CRe^m$의 형태로 상관관계식을 제시하였다. 이러한 상관관계식은 향후 판형열교환기 설계시에 기초자료로 활용될 수 있을 것으로 판단된다.

주름높이의 변화를 고려한 판형열교환기의 완전발달유동 및 열전달 수치해석 (Numerical Simulation of the Fully Developed Flow and Heat Transfer of a Plate Heat Exchanger Taking into Account Variation in the Corrugation Height)

  • 모정하
    • 대한기계학회논문집B
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    • 제36권1호
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    • pp.1-8
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    • 2012
  • 본 연구에서는 주름높이가 고려된 판형열교환기의 완전발달유동 및 열전달특성을 수치적으로 해석하였다. 여러 개의 단위셀(5개 또는 7개)을 연결한 다중셀에 입구부와 출구부가 부착된 모델을 기본으로 P/H비 변화($2.0{\leq}P/H{\leq}4.0$)에 따른 모델에 대하여 수치해석을 수행하였다. 작동유체는 물이며, 수치조건은 쉐브론각 $20^{\circ}$, $300{\leq}Re{\leq}1,500$이다. 그리고 마찰인자는 $f=CRe^m$의 형태로, Colburn 계수는 $j=CRe^m$의 형태로 상관관계식을 제시하였다. 수치해석 결과 완전발달유동은 세 번째 셀부터 시작되었으며, 누셀트수는 P/H비가 작을수록 큰 값을 나타냈다.

자동차용 응축기의 휜 열전달 및 압력강하 특성 (Characteristics of Fin-Side Heat-Transfer and Pressure Drop in a Condenser for Automobile)

  • 곽경민;이홍열
    • 한국자동차공학회논문집
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    • 제12권3호
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    • pp.152-158
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    • 2004
  • An experimental study was performed to determine the fin-side heat transfer and pressure drop of a condenser for automobile. Five sample with different fin height and louver angle were tested, 9mm, 8mm, 7.5mm, 5.4mm and 4.5mm. Results are presented as plot of Colburn j-factor(or heat transfer coefficients) and friction factor(or pressure drop) against the Reynolds number(or inlet air velocity) based on louver pitch, in the range of 110 to 480. The results show that both heat transfer and pressure drop on the fin are mainly affected by the louver angle in a lower range of air velocity, but, by the fin height in a higher range of air velocity. The performance of 5.4mm fin is the highest, compared to other fin sample.

휜-히트파이프로 구성된 채널에서 히트파이프의 엇갈림배열에 따른 유동 및 열전달 특성 (Flow and Heat Transfer Characteristics due to Staggered Arrangement of Heat Pipes in Channels with Heat Pipes and Fins)

  • 김성훈;진윤근;김철주
    • 설비공학논문집
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    • 제14권11호
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    • pp.871-879
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    • 2002
  • The characteristics of flow and heat transfer in the heat exchanger of heat pipes with fins have been studied numerically for cooling enhancement of electronic components of KTX (Korea Train eXpress). Numerical analysis and methodology have been conformed by comparing the experimental results for inlined array of heat pipes. The staggered arrangement of heat pipes has been proposed in order to achieve heat transfer enhancement. As results, the geometry change to the staggered array is conformed to increase the heat transfer of the system accompanied by an increase of pressure drop. The current results of friction factor and Colburn j factor are presented in terms of Reynolds number and staggered distance, and are expected to use for design and manufacture of such a system.

습표면 조건에서 슬릿 핀-튜브 열교환기의 열전달 및 압력강하 특성 (Heat Transfer and Friction Characteristics of Slit Fin and Tube Heat Exchangers in Wet Conditions)

  • 장근선
    • 설비공학논문집
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    • 제19권1호
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    • pp.1-9
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    • 2007
  • Water condensate accumulated on the surface of a fin-and-tube heat exchanger significantly affects its thermal and hydraulic performance. The purpose of this study is to investigate the effect of condensate retention on the air-side heat transfer performance and flow friction. Total 12 samples of slit and plate fin-and-tube heat exchangers with varying fin spacing and number of tube rows are tested under dry and wet conditions. The thermal fluid measurements are made using a psychometric calorimeter. Frontal air velocity varies in the range from 0.7 m/s to 1.5 m/s. Using the experimental data, presented are the heat transfer coefficients in terms of Colburn j-factor and friction factor.

설계 조건에 따른 7mm 직경 핀-관 열교환기의 성능비교 (Performance Comparison of 7mm Fin-Tube Heat Exchangers for Various Design Conditions)

  • 장근선;김혁;홍석률;김영재
    • 대한설비공학회:학술대회논문집
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    • 대한설비공학회 2006년도 하계학술발표대회 논문집
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    • pp.633-638
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    • 2006
  • This study presents the air side heat transfer and friction characteristics of fin-tube heat exchangers with various fin types. A total of 8 samples of heat exchangers are tested. Fin patterns tested are slit, louver and plate fins. Each fin type has three cases of number of tube rows(N=1, 2, 3) and two different fin pitches. The results are plotted in terms of Colburn j-factor and friction factor f with respect to Reynolds number in the range of 200 to 510.

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Louver-Fin 열교환기의 열전달 특성 실험 연구 (Experimental Study of Heat Transfer Performance of Louver-Fin Heat Exchanger)

  • 장근선;권영철;홍석률;김재덕;이현수;박병권
    • 대한설비공학회:학술대회논문집
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    • 대한설비공학회 2007년도 동계학술발표대회 논문집
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    • pp.209-215
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    • 2007
  • This study presents the air side heat transfer and friction characteristics of fin-tube heat exchangers. Variations of heat transfer performance in each row are investigated in the present work. Experiments were performed for the Louver fin-tube heat exchangers using air-enthalpy type calorimeter, which is based on air-enthalpy method described in ASHRAE standards. The air velocity was varied from 0.7 to 2.5 m/s with 0.3 m/s interval. The results are plotted in terms of Colburn j-factor and friction factor of with respect to Reynolds number in the range of 200 to 1100.

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