• Title/Summary/Keyword: 압력강하

Search Result 779, Processing Time 0.096 seconds

Prediction and Experiment of Pressure Drop of R22 and R134a on Design Conditions of Condenser (응축기의 설계조건에서 R22와 R134a의 압력강하 예측 및 실험)

  • Kang, Shin-Hyung;Byun, Ju-Suk;Kim, Chang-Duk
    • Journal of Energy Engineering
    • /
    • v.15 no.4 s.48
    • /
    • pp.243-249
    • /
    • 2006
  • An experimental study on the refrigerant-side pressure drop of slit fin an tube heat exchanger has been carried out. A comparison was made between the predictions of previously proposed empirical correlations and experimental data for the pressure drop on design conditions of condenser in micro-fin tube for R22 and Rl34a. Experiments were carried out under the conditions of inlet refrigerant temperature of $60^{\circ}C$ and mass fluxes varying from $150\;to\;250\;kg/m^{2}s$ for R22 and Rl34a. The inlet air conditions are dry bulb temperature of $35^{\circ}C$, relative humidity of 40% and air velocity varying from 0.68 to 1.43 m/s. Experiments show that pressure drop for R134a was $22{\sim}22.6%$ higher than R22 for the degree of subcooling $5^{\circ}C$ For the mass fluxes of $200{\sim}250\;kg/m^{2}s$, the deviation between the experimental and predicted values for the pressure drop was less than ${\pm}20%$ for R22 and Rl34a.

Study on Design Factor and Design-code Development for Plate Type Heat Exchangers (판형 열교환기의 주요 설계인자와 설계프로그램 개발에 관한 고찰)

  • Ko, Jea-Hyun;Park, Kweon-Ha;Song, Young-Ho
    • Journal of Advanced Marine Engineering and Technology
    • /
    • v.36 no.8
    • /
    • pp.1003-1009
    • /
    • 2012
  • Heat exchanger has been widely used in the industry which needs energy transport, and the application of the plate type heat exchanger having high efficiency has been greatly increased. In this study main design parameters are analyzed and new equations are induced. The induced formulation was compared with a commercial program in order to design an optimal heat exchanger. The equations of heat transfer coefficient and pressure drop for Chevron angles are introduced as functions of Reynolds number. The program implemented the equations is tested with Chevron angle variation. The results show that the convective heat transfer coefficients take errors within 8% and the pressure drops have errors within 5% in the analysis conditions.

Improvement on Pressure Drop Performance of Flow Control Disk in Portable Resuscitator (CFD 해석을 통한 인공호흡기 유량조절디스크의 압력 강하 성능개선)

  • Kim, Young-Soo;Kim, Min-Wook;Park, Yong-Hwan
    • Fire Science and Engineering
    • /
    • v.30 no.1
    • /
    • pp.1-5
    • /
    • 2016
  • Cases of cardiac arrests due to cardiovascular ailments have increased recently., portable Current portable resuscitators which can be automatically supply oxygen operated by the pressure of supplied oxygen without manual or electronic actuators are now widely used in emergency worldwide. However, reductions in Pressure drop characteristics through the extended use of this type of resuscitator, however, is are not well-known described. This paper describes the reduction in pressure loss drop performance of the various holes in within the flow control disc of with various hole size of the portable resuscitators using on breathing resistance through the CFD simulation, and suggests the an optimum optimal design of the hole shapes for the minimization of alteration in order to minimize this pressure drops.

An Investigation of Pressure Drop Characteristics of Finned Rod Bundles (핀 봉다발의 압력강하 특성 연구)

  • Chung, Moo-Ki;Chung, Chang-Hwan;Chung, Heung-June;Song, Chul-Hwa;Yang, Sun-Kyu
    • Nuclear Engineering and Technology
    • /
    • v.23 no.3
    • /
    • pp.328-339
    • /
    • 1991
  • A multi-purpose research reactor called KMRR has been developed by Korea Atomic Energy Research Institute(KAERI) to generate a maximum thermal output of 30 MW. As a part of thermal hydraulics study, pressure drop characteristics of the longitudinally finned fuel rod bundles were experimentally investigated in a recirculating water test loop. The present study is focused on the investigation of fin effects on pressure drop and the development of pressure drop correlation for the finned rod bundles in a wide range of flow conditions. Friction factor correlations for each design of the finned rod bundles are developed. The value of friction factor for the finned rod bundles was higher than the analytical solution (64/Re) of laminar circular channel new but became lower than the Blasius equation as Reynolds number was increased.

  • PDF

An Experimental Study on Pressure Drop and Heat Transfer Coefficient of Laminar Ag Nanofluid Flow in Mini-Tubes (은 나노유체의 미세관내 층류 유동의 압력강하 및 열전달계수에 관한 실험적 연구)

  • Kwon, Jeong-Tae;Nahm, Taek-Hun;Kim, Tae-Wan;Kwon, Young-Chul
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.10 no.12
    • /
    • pp.3525-3532
    • /
    • 2009
  • This study presents the heat transfer and pressure drop characteristics of Ag nanofluid in mini-tubes(outer diameters of 1/8inch, 3/16inch). Experiments were performed for Reynolds numbers ranged from 500 to 2,500 and nanofluid concentrations of 0.1 and 0.3vol.%. The pressure drop of nanofluid flow increased by max. 21% compared with that of distilled water. The heat transfer coefficients of the nanofluid of 0.1 vol.% enhanced 3~42% for 1/8inch tube, and 3~69% for 3/16inch tube. Also, the heat transfer coefficients of the nanofluid of 0.3 vol.% enhanced 35~65% for 1/8inch tube, and 62~125% for 3/16inch tube. From the results Ag nanofluid can be a better candidate as a coolant than distilled water when using in mechanical and/or electronic systems.

Numerical Analysis of the Effect of Rounded Tube at the Counter Flow Manifold on the Performance of a Heat Exchanger Used in High Temperature and High Pressure System (대향류 매니폴드 내의 튜브 라운드 적용에 따른 고온 고압 열교환기의 성능특성에 관한 수치적 연구)

  • Kim, Sang-Jo;Choi, Byoung-Ik;Kim, Kui-Soon;Son, Chang-Min;Ha, Man-Young;Jeong, Ji-Hwan;Go, Jeong-Sang
    • Journal of the Korean Society of Propulsion Engineers
    • /
    • v.15 no.6
    • /
    • pp.47-55
    • /
    • 2011
  • The present paper deals with numerical analysis to investigate the effect of rounded tube on the pressure drop and heat transfer in a compact tubular heat exchanger designed for high temperature and high pressure system. The pressure drop and heat transfer in the tubular heat exchanger greatly depend on the location of rounded tubes. The effect of locations of the rounded tubes was also analyzed. Three different locations which were tube inlet, tube outlet, and inlet&outlet were considered. In this paper, the tube with a rounded inlet&outlet showed the minimum pressure drop with decreased heat transfer while the tube with a rounded outlet showed better characteristics of pressure drop and heat transfer compared with the results of original model.

Effect of the lubrication oil on heat transfer and pressure drop characteristics of supercritical carbon dioxide in a microfin tube (마이크로핀관내 냉동기유가 초임계 이산화탄소의 열전달과 압력강하에 미치는 영향)

  • Ku, Hak-Keun
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.13 no.4
    • /
    • pp.1440-1446
    • /
    • 2012
  • This paper presents an experimental study of heat transfer and pressure drop characteristics of supercritical carbon dioxide with PAG inside a horizontal microfin tube. Heat transfer coefficient and pressure drop gradients were measured at 10 MPa in pressure and 520 kg/$m^2s$ in mass flux with variation of PAG mass concentration from 0.06% to 2.26%. The tendencies of both heat transfer and frictional pressure drop characteristics show the same as those of pure $CO_2$ up to 0.3% in PAG mass concentration. In case of 2.26% in PAG mass concentration, measured heat transfer coefficients showed 50% lower than those of pure $CO_2$ near the pseudocritical temperature and measured frictional pressure drop gradients show 1.6 times higher in comparison with those of pure $CO_2$ at $60^{\circ}C$ in $CO_2$ bulk temperature.

Development of New Correlation and Assessment of Correlations for Two-Phase Pressure Drop in Rectangular Microchannels (사각 마이크로채널 내의 2 상 유동 압력강하 상관식의 검증 및 개발)

  • Choi, Chi-Woong;Yu, Dong-In;Kim, Moo-Hwan
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.34 no.1
    • /
    • pp.9-18
    • /
    • 2010
  • There are two kinds of models in two-phase pressured drop; homogeneous flow model and separated flow model. Many previous researchers have developed correlations for two-phase pressure drop in a microchannel. Most correlations were modified Lockhart and Martinelli's correlation, which was based on the separated flow model. In this study, experiments for adiabatic liquid water and nitrogen gas flow in rectangular microchannels were conducted to investigate two-phase pressure drop in the rectangular microchannels. Two-phase frictional pressure drop in the rectangular microchannels is highly related with flow regime. Homogeneous model with six two-phase viscosity models: $Owen^{(21)}$'s, $MacAdams^{(22)}$'s, Cicchitti et ${al.}^{(23)}$'s, Dukler et ${al.}^{(24)}$'s, Beattie and ${Whalley}^{(25)}$'s, Lin et ${al.}^{(26)}$'s models and six separated flow models: Lockhart and $Martinelli^{(27)}$'s, ${Chisholm}^{(31)}$'s, Zhang et ${al.,}^{(15)}$'s, Lee and ${Lee}^{(5)}$'s, Moriyama and ${Inue}^{(4)}$'s, Qu and $Mudawar^{(8)}$'s models were assessed with our experimental data. The best two-phase viscosity model is Beattie and Whalley's model. The best separated flow model is Qu and Mudawar's correlation. Flow regime dependency in both homogeneous and separated flow models was observed. Therefore, new flow pattern based correlations for both homogeneous and separated flow models were individually proposed.

An Experimental Investigation on Condensation Heat Transfer Inside Vertical Tubes (수직관내 응축열전달에 관한 실험적 연구)

  • 윤정인;김재돌;김성규
    • Journal of Advanced Marine Engineering and Technology
    • /
    • v.20 no.4
    • /
    • pp.59-69
    • /
    • 1996
  • 냉동.공조 및 각종 화학공업에 널리 사용되는 열교환기인 응축기의 고성능화 및 합리적인 설계를 위해서는 냉매의 정확한 응축열전달률 예측과 그 메카니즘 규명이 필수 요건이다. 본 연구에서는 내경 9.7mm, 외경 12.7mm, 길이 1200mm의 수직 이중관 응축기의 압력강하 및 응축열전달특성을 실험적으로 밝혔다. 실험으로부터 Lockart-Martinelli의 상관 관계식을 이용한 수직 응축관내 압력강하 특성을 종래의 실험식들과 비교.검토하고 새로운 압력강하식을 제안하였다. 그리고 종래의 해석방법과는 달리 비환상류 모델을 가정한 해석결과로부터 전 유동양식에 걸쳐 적용할 수 있는 새로운 응축열전달 예측식을 제안하였다.

  • PDF