• Title, Summary, Keyword: Heat Exchanger

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Heat Transfer Characteristics of Fin-Tube Heat Exchanger using Two-Port Tube of Small Inner Diameter by Mechanical Expansion (연결세경관을 이용한 휜관형 열교환기의 기계확관에 의한 전열특성)

  • Lee, Sangmu;Park, Byung-Duck
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.28 no.11
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    • pp.428-433
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    • 2016
  • The fin and tube heat exchanger using a two-port tube has in air-conditioner heat exchanger because heat transfer performance. This study investigates the feasibility of a fin and tube heat exchanger using two-port copper tube by mechanical expansion. The optimum size of the tube-expanding bullet for the heat exchanger using two-port tube was through numerical calculation. The heat exchanger using a two-port tube was fabricated by mechanical expansion, and the heat exchanger performance was evaluated condensation and evaporation experiments. Compared to the heat exchanger of a conventional circular tube, the pressure drop per unit length of the heat exchanger with a two-port tube decreased. Compared to the heat exchanger using a conventional circular tube, the overall heat transfer coefficient of heat exchanger with a two-port tube increased up to 13% in the case of condensation, and up to 25% in the case of evaporation. The two-port tube heat exchanger outperforms conventional heat exchanger for air conditioner with a inner grooved circular tube.

Local and Overall Heat Transfer Characteristics of Fin- Flat Tube Heat Exchanger with Vortex Generators

  • Yoo, Seong-Yeon;Chung, Min-Ho;Park, Dong-Seong
    • International Journal of Air-Conditioning and Refrigeration
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    • v.11 no.3
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    • pp.150-157
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    • 2003
  • Local and overall heat transfer characteristics of fin-flat tube heat exchangers with and without vortex generators were investigated. Local heat transfer coefficients were measured with the heat exchanger model using naphthalene sublimation technique. In case of a fin-flat tube heat exchanger without vortex generators, only the horseshoe vortices formed around tubes augment the heat transfer. On the other hand, longitudinal vortices created artificially by vortex generators additionally enhance heat transfer in case of a fin-flat tube heat exchanger with vortex generators. Overall heat transfer coefficients were measured with the prototypes of the fin-flat tube heat exchanger with and without vortex generators in a wind tunnel and results were compared with those of a fin-circular tube heat exchanger with wavy fin. Friction losses for heat exchangers were also measured and compared. The fin-flat tube heat exchanger with vortex generators is found to be more effective than the fin-circular tube heat exchanger with wavy fin.

A Study on Heat Transfer Characteristics in the Air Side of Louvered Fin Heat Exchanger (루우버핀형 열교환기의 공기측 열전달 특성에 관한 연구)

  • Kim, Sun-Jung
    • Journal of the Korean Solar Energy Society
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    • v.23 no.1
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    • pp.9-16
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    • 2003
  • For the study of an effect that fin thickness and shape of heat exchanger have on the elevation of heat transfer efficiency, we make models of plate fin type heat exchanger and louvered fin type heat exchanger which was given a transformation of fin thickness in plate f)n type heat exchanger and louvered fin type heat exchanger which are often used now. And the effect of fin thickness on pressure drop and characteristics of heat transfer was experimented and analysed when air velocity and temperature of plate heating was a variable. The results of experiment shows below. Pressure drop shows larger in louvered fin type exchanger than in plate fin type exchanger, size of pressure drop shows like this order that fin thickness is 0.3mm, 0.2mm, 0.1mm. Mean heat transfer coefficient shows higher in louvered fin type exchanger than in plate fin type exchanger, size of mean heat transfer coefficient by fin thickness shows same in both case in louvered fin type heat exchanger and plate fin type exchanger like this order that fin thickness is 0.1mm, 0.2mm, 0.3mm.

A study on the behavior of frost formation according to surface characteristics in the fin-tube heat exchanger (핀-관 열교환기의 표면특성에 따른 착상 거동에 관한 연구)

  • 류수길;이관수
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.11 no.3
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    • pp.377-383
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    • 1999
  • In this study, the behavior of frost formation according to surface characteristics in the fin-tube heat exchanger has been examined experimentally. The results show that the thickness of the frost which is attached to the hydrophilic heat exchanger becomes thin and the air pressure drop is smaller than that of bare aluminium heat exchanger However, the frost mass of hydrophilic heat exchanger is more than the bare one. Hence, high density frost is attached to hydrophilic heat exchanger. The sensible and latent heat flux of hydrophilic heat exchanger is bigger than that of bare one, but the increasing amount is very small and the improvement of thermal performance is also very small. The variation of fin-pitch of heat exchanger shows little influence on frost formation and hydrophilic heat exchanger loses its surface characteristics rapidly with increasing relative humidity.

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Thermal Performance Analysis of a Shell-and-Tube Heat Exchanger with Plate Fins of Various Shape (다양한 형상의 판형 휜을 장착한 원통다관형 열교환기의 열성능 해석)

  • 신지영;손영석
    • Journal of the Korean Society of Marine Engineering
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    • v.28 no.4
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    • pp.648-656
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    • 2004
  • In this study, a highly efficient shell-and-tube heat exchanger with plate fins is considered to improve thermal performance of the conventional shell-and-tube heat exchanger. This type of shell-and-tube heat exchanger with plate fins of various shape is simulated three-dimensionally using a commercial thermal-fluid analysis code. CFX4.4. The effect of the shape of the plate fin on heat transfer characteristics is also investigated by the simulation. Plate fins of four different shapes. plane, plane-slit. wave. and wave-slit fins, are considered. The flow fields, pressure drop and heat transfer characteristics in the heat exchanger are calculated. It is proved that the shell-and-tube heat exchanger with plate fins is superior to the conventional shell-and-tube heat exchanger without plate fins in terms of heat transfer. The shape of the plate fin is important in the performance of a heat exchanger such as heat transfer and pressure drop.

Performance of a Shell-and-Tube Heat Exchanger with Spiral Baffle Plates

  • Son, Yeong-Seok;Sin, Ji-Yeong
    • Journal of Mechanical Science and Technology
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    • v.15 no.11
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    • pp.1555-1562
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    • 2001
  • In a conventional shell-and-tube heat exchanger, fluid contacts with tubes flowing up and down in a shell, therefore there is a defect in the heat transfer with tubes due to the stagnation portions . Fins are attached to the tubes in order to increase heat transfer efficiency, but there exists a limit. Therefore, it is necessary to improve heat exchanger performance by changing the fluid flow in the shell. In this study, a highly efficient shell-and-tube heat exchanger with spiral baffle plates is simulated three-dimensionally using a commercial thermal-fluid analysis code, CFX4.2. In this type of heat exchanger, fluid contacts with tubes flowing rotationally in the shell. It could improve heat exchanger performance considerably because stagnation portions in the shell could be removed. It is proved that the shell-and-tube heat exchanger with spiral baffle plates is superior to the conventional heat exchanger in terms of heat transfer.

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Performance Test of Low Temperature Waste Heat Recovery Heat Exchanger Using Self-excited Oscillating Heat Pipe (자려 진동형 히트 파이프를 이용한 저온 폐열 회수 열교환기의 성능 실험)

  • 이욱현;이종현;김종수
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.12 no.9
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    • pp.853-859
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    • 2000
  • In this study, low temperature waste heat recovery heat exchanger was developed using a principle of self-excited oscillating heat pipe. The heat exchanger of serpentine type was composed of extruded flat aluminum tube with 6 channels (3 nm$\times$ 2.75nm) and louvered fin. The heat transfer area density of heat exchanger was $331.9 m^2/m^3$. Working fluid is R141b and charge ratio was 40% by volume. Heat transfer rate and the effectiveness of heat exchanger was primary concern of this study. As a result, the effectiveness of heat exchanger was about 0.4-0.67, and recovered waste heat rate was about 4.5 kW per one unit of heat exchanger.

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A study on the Heat Transfer Performance according to Ground Heat Exchanger Types (지중열교환기의 종류에 따른 열전달 성능에 관한 연구)

  • Hwang, SuckHo;Song, Doosam
    • KIEAE Journal
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    • v.10 no.4
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    • pp.75-80
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    • 2010
  • Generally, ground-source heat pump (GSHP) systems have a higher performance than conventional air-source systems. However, the major fault of GSHP systems is their expensive boring costs. Therefore, it is important issue that to reduce initial cost and ensure stability of system through accurate prediction of the heat extraction and injection rates of the ground heat exchanger. Conventional analysis methods employed by line source theory are used to predict heat transfer rate between ground heat exchanger and soil. Shape of ground heat exchanger was simplified by equivalent diameter model, but these methods do not accurately reflect the heat transfer characteristics according to the heat exchanger geometry. In this study, a numerical model that combines a user subroutine module that calculates circulation water conditions in the ground heat exchanger and FEFLOW program which can simulate heat/moisture transfer in the soil, is developed. Heat transfer performance was evaluated for 3 different types ground heat exchanger(U-tube, Double U-tube, Coaxial).

Experimental Study on Thermal Characteristics of Heat Exchanger Modules for Multi Burner Boiler (멀티버너 보일러용 열교환기 모듈 특성 시험 - 모듈 순서에 따른 특성결과 -)

  • Kang, Sae-Byul;Kim, Jong-Jin;Ahn, Joon
    • Proceedings of the KSME Conference
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    • pp.3053-3058
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    • 2008
  • We develop a heat exchanger modules for a multi-burner boiler. The heat exchanger module is kind of a heat recovery steam generator (HRSG). This heat recovery system has 4 heat exchanger modules. The 1st module consists of 27 bare tubes due to high temperature exhaust gas and the others consist of 27 finned tubes. The maximum steam pressure of each module is 1 MPa and tested steam pressure is 0.7 MPa. In order to test these heat exchanger modules, we make a 0.5t/h flue tube boiler (LNG, $40\;Nm^3/h$). We tested the heat exchanger module with changing the position of each heat exchanger module. We measured the inlet and outlet temperature of each heat exchanger module and calculated the heat exchange rate. The results show that if module C is placed at second stage (the 1st stage is always module O, bare tube module), there is no need to attach an additional heat exchanger module. In this case the exit temperature of module C is low enough to enter an economizer which is more effective in heat recovery than a heat exchanger module.

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A Study on the Characteristics of Pressure Distribution for Heat Exchanger Types of Domestic Gas Boiler (가정용 가스보일러 열교환기 유형에 따른 압력분포특성에 관한 연구)

  • 최경석;오율권;차경옥
    • Journal of the Korean Society of Safety
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    • v.16 no.4
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    • pp.22-28
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    • 2001
  • Heat transfer and pressure distribution for heat exchanger type of domestic gas boiler are different from shape, pitch, thickness of fin and array of pipe respectively. In order to measure the pressure distribution across the heat exchanger, a suction type wind tunnel was constructed and velocity distribution was measured for pilot tube(4 point) of rack type. The experiments were performed for 5 different air flow mass, rpm=3,6,9,12,15 and transverse axis of heat exchanger(x-length) is 5cm respectively. Results showed that above 9.5m/s, pressure distribution dispersion for wet type of heat exchanger is on the increase and above 5.5m/s, pressure distribution dispersion for dry type of heat exchanger is on the increase. Also, pressure distribution dispersion by comparing two different types heat exchanger, dry type of heat exchanger showed a higher augmentation than wet type of heat exchanger.

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