• Title/Summary/Keyword: Flow friction loss

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The Comparative Experiment of Duct Design Method with Equal Friction Loss Method and T-Method on a House Ventilation System (등압법과 T-Method법을 이용한 주택환기시스템 덕트설계법의 비교실험)

  • Joo, Sung-Yong;Kim, Kwang-Hyun;Choi, Seok-Yong;Yee, Jurng-Jae
    • Proceedings of the SAREK Conference
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    • 2006.06a
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    • pp.99-104
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    • 2006
  • Accurate flow rate distribution has been become a very important part for controling of air change rate since the introduction of house ventilation system. An inappropriate selection of fan due to Incorrect prediction of friction loss makes waste energy. The purpose of this study is to recognize applicability of T-Method at house ventilation system by comparing experiment with T-method, The result of this study is as follows Flow rate is small amount in a house, so duct size must be accurate. And duct design with Equal Friction Loss Method presented large error range. Equal friction loss method is not fit to applicate small amount air flow rate. T-Method predicts accurate flow rate comparatively in a house ventilation system. Error range was 3.5%.

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Velocity and Flow Friction Characteristic of Working Fluid in Stirling Engine Regenerator (II) - Flow Friction Characteristic of Working Fluid in Stirling Engine Regenerator - (스털링기관 재생기내의 작동유체 유속 및 마찰저항 특성(II) - 작동유체 유동마찰저항 특성 -)

  • Kim, T.H.;Choi, C.R.
    • Journal of Biosystems Engineering
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    • v.33 no.1
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    • pp.1-6
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    • 2008
  • The output of the Stirling engine is influenced by the regenerator effectiveness. The regenerator effectiveness is influenced by heat transfer and flow friction loss of the regenerator matrix. In this paper, in order to provide basic data for the design of regenerator matrix, characteristics of flow friction loss were investigated by a packed method of matrix in the oscillating flow as the same condition of operation in a Stirling engine. As matrices, two different wire screens were used. The results are summarized as follows; 1. With the wire screen of No. 50 as regenerator matrices, pressure drop of working fluid of the oscillating flow is shown as 3 times higher than that of one directional flow, not too much influenced by the number of packed meshes. 2. With the wire screen of No. 100 as regenerator matrices, pressure drop of working fluid of the oscillating flow is shown as 2.5 times on the average higher than that of one directional flow, not too much influenced by the number of packed meshes. 3. Under one directional flow which used regenerator matrices with both 200, 240, and 280 wire screens of No. 50 and 320, 370, and 420 wire screens of No. 100, the relationship between the friction factor and Reynold No. is shown as the following formula. $$f=\frac{0.00326639}{Re\iota}-1.29106{\times}10^{-4}$$ 4. Under oscillating flow which used regenerator matrices with both 200, 240, and 280 wire screens of No. 50 and 320, 370, and 420 wire screens of No. 100, the relationship between the friction factor and Reynold No. is shown as the following formula. $$f_r=\frac{0.000918567}{Re\iota}+1.86101{\times}10^{-5}$$ 5. The pressure drop is shown as high in proportion as the number of meshes has been higher, and the number of packed wire screens as matrices increases.

Basic Simulation for Vuilleumier Cycle Heat Pump (VM사이클 히트펌프 기초 설계프로그램)

  • Park, Byung-Duck
    • Journal of the Korean Society of Industry Convergence
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    • v.3 no.3
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    • pp.265-273
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    • 2000
  • Basic simulation program for Vuilleumier cycle heat pump was developed that can use precise VMHP design and analysis. VMHP system was divided 11 sections in simulation. Simulation was used adiabatic model analysis and that considered with heat transfer performance for heat exchanger, regenerator loss, conduction loss, shuttle loss, pumping loss and pressure loss by flow friction. Specially, friction loss of connection pipe between heat compression side and heat pump side, leakage of rod seal and piston seal was considered in the analysis.

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Basic Study on the Regenerator of Stilting Engine (III) - Heat Transfer and Flow Friction Characteristic of the Regenerator with Combined Wire-mesh Matrix - (스털링 기관용 재생기에 관한 기초 연구 (III) - 복합메쉬 철망을 축열재로 한 재생기의 전열 및 유동손실 특성 -)

  • Lee S. M.;Kim T. H.
    • Journal of Biosystems Engineering
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    • v.30 no.4 s.111
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    • pp.195-201
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    • 2005
  • The output of Stirling engine is influenced by the regenerator effectiveness. The regenerator effectiveness is influenced by heat transfer and flow friction loss of the regenerator matrix. In this paper, in order to provide a basic data for the design of regenerator matrix, characteristics of heat transfer and flow friction loss were investigated by a packed method of matrix in the oscillating flow as the same condition of operation in a Stirling engine. As matrices, several kinds of combined wire screen meshes were used. The results are summarized as follows; The packed meshes with high mesh no. in the side of heater part of regenerator showed effective than the packed meshes with low mesh no. in the side of cooler part of regenerator. The temperature difference and pressure drop of the regenerator were not made by the specific surface area of wire screen meshes but by the minimum free-flow area to the total frontal area. Among the No. 150 single screen meshes, 200-60 combined meshes, the 200-150-100 combined meshes showed the highest in effectiveness.

Heat transfer and friction loss characteristics of shaped short pin-fin arrays (짧은 못형핀의 형상 변화에 따른 열전달 및 마찰손실 특성)

  • Cho, H.H.;Goldstein, R.J.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.9 no.3
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    • pp.259-267
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    • 1997
  • Average heat transfer coefficients and friction coefficients have been measured from staggered short pin-fin arrays to investigate the effect of fin shapes. Flow entering into the test section is a fully developed duct flow and the Reynolds number ranges from 5,000 to 25,000 based on fin diameter and average approaching velocity. The fin has three different shapes; uniform-diameter circular fin, two stepped-diameter circular fins. Average heat transfer rates change slightly with the fin shapes. However, friction loss(pressure loss) for the stepped-diameter fins is significantly less than that for the uniform-diameter fin. This results indicate that the stepped-diameter fin arrays in duct flow enhance heat transfer rates largely based on unit pumping power.

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Performance Characteristic Analysis for Open Channel Type Regenerative Pump (개수로형 재생펌프의 특성해석에 관한 연구)

  • Shin, Dong-Yun;Choi, Chang-Ho;Kim, Jin-Han
    • The KSFM Journal of Fluid Machinery
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    • v.10 no.2 s.41
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    • pp.46-53
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    • 2007
  • An improved performance characteristics analysis model of a regenerative pump is proposed in the present paper. For its low characteristic speed, a regenerative pump generates high head with low flow rate. However, the efficiency is fairly low due to the skin friction between impeller and casing. Also, the complexity of its internal flow pattern makes prediction of performance characteristics difficult. In the present research, a one-dimensional analysis model was improved with consideration of disc friction loss, minor loss, and modified flow length, and the result was proven to be close in range with the results from experiments.

The Estimation of Friction Velocity by Hydraulic Parameters Reflecting Turbulent Flow Characteristics in a Smooth Pipe Line (매끄러운 관수로 내 난류흐름특성을 반영한 수리학적 매개변수에 의한 마찰속도의 산정)

  • Choo, Tai Ho;Son, Jong Keun;Kwon, Yong Been;Ahn, Si Hyung;Yun, Gwan Seon
    • The Journal of the Korea Contents Association
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    • v.16 no.4
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    • pp.614-623
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    • 2016
  • Grid(pipe network) design is an important element of Smart Water Grid, which essential to estimate hydraulic parameters such as the pressure, friction factor, friction velocity, head loss and energy slope. Especially, friction velocity in a grid is an important factor in conjunction with energy gradient, friction coefficient, pressure and head loss. However, accurate estimation friction head loss, friction velocity and friction factor are very difficult. The empirical friction factor is still estimated by using theory and equation which were developed one hundred years ago. Therefore, in this paper, new equation from maximum velocity and friction velocity is developed by using integration relationship between Darcy-Weisbach's friction head loss equation and Schlichting equation and regression analysis. To prove the developed equation, smooth pipe data areis used. Proposed equation shows high accuracy compared to observed data. Study results are expected to be used in stability improvements and design in a grid.

Friction loss of multi-purpose stormwater tunnel simulated by Flow 3D (Flow 3D를 이용한 다목적 수로 터널의 마찰 손실 산정)

  • Lee, Du Han;Kim, Jung Hwan;Chung, Gunhui
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.3
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    • pp.14-21
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    • 2017
  • The extreme floods recently are have been attributed global warming, The development of a canal tunnel to prevent floods by making a bypass or undercurrent to flood discharge in a major flooding area is required because urban flooding in heavy rainfall occurs frequently, increasing the impermeability according to lack of capacity in sewage to urbanization by the existing urban basin. In this study, a numerical simulation was performed to support design standards for a multi-purpose waterway tunnel combined road tunnel of canal tunnel. The numerical simulation showed that the size of the friction loss occurring in the tunnel section of the same channel occurred more than the theoretically calculated frictional loss derived from the numerical simulations. This is probably due to the additional frictional loss caused by the change in the flow structure due to the geometry of the pipe when the shape of the channel is non-circular. The increase in friction loss was more pronounced in the laminar flow than in the turbulent flow. Depending on the shape of the conduit, the friction loss should be adjusted for accurate flow calculations. This result can provide the basin information about the design of flood by a pass conduit.

Basic Study on the Regenerator of Stilting Engine (II) - Heat transfer and flow friction loss characteristics of the regenerator with wire screen matrix - (스털링기관용 재생기에 관한 기초연구 (II) - 철망을 축열재로 한 재생기의 전열 및 유동손실특성 -)

  • 김태한;이시민;이정택
    • Journal of Biosystems Engineering
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    • v.27 no.6
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    • pp.529-536
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    • 2002
  • The performance of stilting engine, in particular, its energy conversion efficiencies are critically influenced by the regenerator characteristics. The regenerator characteristics are influenced by effectiveness, void fraction. heat transfer loss and fluid friction loss in the regenerator matrix. These factors were influenced by the surface geometry and material properties of the regenerator matrix. The regenerator design goals arc good heat transfer and low pressure drop of working Bas across the regenerator. Various data for designing a wire screen matrix have been given by Kays and London(1984). The mesh number of their experiment. however, was confined below the No. 60. which seems rather small for the Stirling engine applications. In this paper. in order to provide a basic data for the design of regenerator matrix, characteristics of heat transfer and flow friction loss were investigated by a packed mettled of matrix in oscillating flow as the same condition of operation in a Stirling engine. Seven kinds of sing1e wire screen meshes were used as the regenerator matrices. The results are summarized as follows; 1. While the working fluid flew slowly in the regenerator. the temperature difference was great at the both hot-blow(the working fluid flows from healer to cooler) and cold-blow(the working fluid flows from cooler to healer). On the other hand. while the working fluid flew fast. the temperature difference was not distinguished. 2. The No.150 wire screen used as the regenerator matrix showed excellent performance than tile others. 3. Phase angle variation and filling rate affected heat transfer or regenerator matrices. 4. Temperature difference between the inlet and outlet of the regenerator is very hish in degree of 120 phase angle.

A Study on the Friction Loss Reduction in Fire Hoses Used at a Fire Scene (화재현장에서 사용하는 소방호스의 마찰손실 감소 방안에 관한 연구)

  • Min, Se-Hong;Kwon, Yong-Joon
    • Fire Science and Engineering
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    • v.27 no.3
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    • pp.52-59
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    • 2013
  • It was described the measured friction loss depending on pressure used and changes in water flow rates for a fire hose used at a fire scene on this study. As a result of actual measurement based on the result obtained by analyzing the use situation of a fire hose such as the kind, quantity, pressure used, etc. of a fire hose, the friction loss in a fire hose under the condition of using by a fire officer at a fire scene was measured as up to 56.8 %. This is much different from the equivalent length of a fire hose used to calculate the pump head in an indoor and outdoor fire-fighting facility. There is no related restrictive regulation on friction loss, there are even no data on friction loss measured by fire hose makers, and spreading a fire hose without considering friction loss at a fire scene can result in an increased length of hose used and a high-pressure water discharge from a fire engine, so this study aims to establish a standard for an equivalent length to friction loss in a fire hose and to propose a spreading method considering friction loss in a fire hose at a fire scene.