• Title/Summary/Keyword: Offset strip fin

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Optimization for the Internal Structure of a Recuperator with Offset Strip Fins (오프셋 스트립 휜을 가지는 리큐퍼레이터의 내부 형상 최적화)

  • Do, Kyu-Hyung;Han, Yong-Shik;Choi, Byung-Il;Kim, Myung-Bae
    • Journal of the Korea Institute of Military Science and Technology
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    • v.14 no.6
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    • pp.1178-1185
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    • 2011
  • In the present study, a recuperator is suggested to improve the thermal efficiency of a micro gas turbine. Primary design parameters of the recuperator are determined from the ideal cycle analysis. The counter flow plate-fin heat exchanger with offset strip fins is chosen as the type of the recuperator. In order to satisfy the design constraints which are the minimum effectiveness and the maximum pressure drop, the optimization for the internal structure of the recuperator is performed with varying the fin spacing and the fin height of offset strip fins. Also the effects of the thermal conductivity of fins and separation plates and the longitudinal heat conduction on the thermal performance of the recuperator are investigated.

A Study on the Effect of Fin Pitch of Offsets Strip Fin on Heat Transfer of High Prandtl Fluid (옵셋 스트립 휜의 휜피치가 고 Prandtl 유체 열전달 특성에 미치는 영향)

  • 강덕종;양대일;전승환;정형호
    • Journal of Advanced Marine Engineering and Technology
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    • v.26 no.1
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    • pp.83-89
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    • 2002
  • In the present study, heat transfer characteristics of oil flow over offset strip fins were predicted by the numerical methods. Oil flow in the plate-fin passage was idealized by 2 dimensions. The flow patterns and heat transfer characteristics were predicted in details. Numerical results shows that the average convective heat transfer coefficients are almost independent on the raws of fins and affected by fin pitches. At the rear face of fin, there exists minimum point of heat transfer coefficients where stream are separated from the fin surfaces. The convective heat transfer coefficients were effected by separation bubbies which appeared at the wake region of offset strip fins.

Counter-Current Gas-Liquid Two-Phase Flow in Narrow Rectangular Channels with Offset Strip Fins (휜이 있는 협소 사각 유로에서 대향류 기/액 2상 유동)

  • Sohn, B.H.;Kim, B.J.;Jeong, S.
    • Proceedings of the KSME Conference
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    • 2001.06e
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    • pp.229-234
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    • 2001
  • An adiabatic counter-current vertical two-phase flow of air and water in narrow rectangular channels with offset strip fm was investigated experimentally. Tests were systematically performed with downward liquid superficial velocities and upward gas velocities covering 0 to 0.06 m/s and 0 to 2.5 m/s ranges, respectively. Two-phase flow regimes were classified by examining the video images of flow patterns in transparent test sections of 760 mm long and 100 mm wide channel with gaps of 3.0 and 5.0 mm. The channel average void fraction was measured by the quick-closing valve method. Unlike the flow regimes in the channels without fin, where bubbly, slug, chum, and annular flow were identified, only bubbly and chum flow regimes were found for the channels with offset strip fin. However the existence of fin in the channels showed negligible effects on the void fraction. Instead counter-current flow limitations were found to happen at lower air superficial velocity once offset strip fin was introduced in narrow rectangular channels.

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CFD Analysis of Offset Strip Fin with a Gap between Rows (CFD를 이용한 핀의 열 사이에 간극을 가지는 Offset Strip Fin의 성능 해석)

  • Hwang, Seongwon;Jeong, Ji Hwan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.26 no.8
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    • pp.381-387
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    • 2014
  • The off-set strip fins (OSF) have been widely used to construct plate-fin heat exchangers. Conventional OSF is constructed in successive rows of fins. New OSF structure is suggested to have a gap between adjacent rows of fins. The gap is intended to reduce fouling by allowing small objects to flow through fins. The objective of this work is to investigate the performance of off-set strip fins with gap between successive rows. Results showed that the performance of OSF with gap can't be predicted by previous correlation.

2 Dimensional Correlations of Heat Transfer of Oil Flows over Offset Strip Fins (옵셋 스트립 휜을 가로지르는 오일유동의 열전달 2차원 상관관계식)

  • 강덕종;신성학;정형호
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.14 no.9
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    • pp.734-740
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    • 2002
  • In the present study, heat transfer characteristics of oil flow over offset strip fins are predicted by the numerical methods. Oil flow in the plate-fin passage is idealized by 2 dimensions. Inlet velocity, Prandtl number and fin pitch ratio are chosen as parameters which affect the heat transfer of offset strip fins. The effect of parameters on pressure drops and convective heat transfer coefficients are described. Characteristic length is derived in case of 2 dimensional flow situation. Correlations for friction factor and convective heat transfer coefficient are derived.

Optimum Design of Offset-Strip Fins (옵셋 스트립 휜 최적 설계)

  • Kim, Min-Soo;Lee, Kwan-Soo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.34 no.5
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    • pp.531-537
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    • 2010
  • This paper optimized the design parameters of the offset strip fin in a heat exchanger. To decrease the pressure drop and increase heat transfer, the performance factors such as j/f, $j/f^{1/3}$, and JF, which could be used to estimate the pressure drop and heat transfer simultaneously, were employed as the criteria for optimization. In the present study, STDQAO, PQRSM, and MGA were used for solving the constrained nonlinear optimization problem. The JF factor and heat transfer performance of the optimized offset-strip fin were greater than those of the reference offset-strip fin by 36% and 280%, respectively.

Thermal Analysis of Compact Circular Water Cooled Engine Oil Cooler (고집적 원통형 수냉식 엔진 오일쿨러의 열적 해석)

  • 윤준규
    • Journal of Advanced Marine Engineering and Technology
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    • v.22 no.6
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    • pp.771-781
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    • 1998
  • A highly compact and thermally efficient water cooled oil cooler for automotive use without offset strip fin and casing is developed in this study. The study result has shown that eliminating the fin and casing in the oil cooler the manufacturing process and cost and can be simplified and reduced greatly without sacrificing the thermal capacity. The oil cooler developed in the study uses the dimply type heat transfer core element design instead of offset strip fin and eliminates the outer casing for coolant water flow by applying specially made parallel loop flow design. In the study the thermal design program for the present oil cooler also was developed and validated experimentally.

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Experimental Study on Heat Transfer Characteristics of Oil Cooler Inserted Offset Strip Fin (옵셋 스트립 휜 삽입 오일쿨러의 열전달에 관한 실험적 연구)

  • Yoo, Jung-Won;Park, Jae-Hong;Kwon, Yong-Ha;Kim, Young-Soo;Lee, Byung-Kil
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.1237-1242
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    • 2004
  • In this study, single-phase heat transfer experiments were conducted with oil cooler with offset strip fin using water. An experimental water loop has been developed to measure the single-phase heat transfer coefficient in a vertical oil cooler. Downflow of hot water in one channel receives heal from the cold water upflow of water in the other channel. Similar to the case of a plate heat exchanger, even at a very low Reynolds number, the flow in the on cooler with offset strip fin remains turbulent. The present data show that the heat transfer coefficient increases with the Reynolds number. Based. On the present data, empirical correlation of the heat transfer coefficient was proposed. Also, performance prediction analysis for oil cooler were executed and compared with experiments. ${\varepsilon}-NTU$ method was used in this prediction program. Independent variables are flow rates and inlet temperature. Compared with experimental data, the accuracy of the program is within the error bounds of ${\pm}5$% in the heat transfer rate.

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A Study on the Heat Transfer Characteristics of Oil Flow over Offset Strip Fins (옵셋 스트립 휜에서 오일유동의 열전달 특성에 관한 연구)

  • 양대일;정형호
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.13 no.11
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    • pp.1134-1140
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    • 2001
  • In the present study, heat transfer characteristics of oil flow over offset strip fins were predicted by the numerical methods. Oil flow in the plate-fin passage was idealized by 2 dimension. Power law scheme and SIMPLE algorithm were used for convective diffusion formulation and pressure term respectively. Governing equations were discretized by control volume formulation. The flow patterns and heat transfer were predicted in details. The convective heat transfer coefficients were affected by separation bubbles which appeared at the wake region of offset strip fins.

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An Experimental Study on the Thermal Resistance Characteristics of Layered Heat Sink (적층형 Heat Sink의 열저항 특성에 관한 실험적 연구)

  • 김종하;윤재호;권오경;이창식
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.13 no.4
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    • pp.271-287
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    • 2001
  • This paper has been made to investigate the thermal performance characteristics for the several types of layered aluminum heat sinks with offset-strip fin. Heat sinks with different fin height, fin length, number of fin layer and slanted fin are prepared and tested for natural convection as well as forced convection. The experimental results for layered heat sink(LHS) are compared to those for advanced pin fin heat sink (PHS) so that the appropriate heat sink can be designed or chosen according to the heating conditions. The overall heat transfer performances for LHS are almost comparable to those of PHS under natural convection, and become 1.2∼1.5 times as high as those of PHS under forced convection situation. This study shows that fin height and number of fin layer re important parameters, which have a serious influence on thermal performance for layered heat sinks.

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