• Solar Energy
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• v.14 no.2
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• pp.51-60
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• 1994

The fluidization characteristics of the furan foundry sand fluidized bed and the heat transfer characteristics on a single spiral coil tube in the bed have been investigated. In the paper, the heat transfer coefficients for a single spiral coil tube are measured in the furan foundry sand bed as a function of the ratio of heated coil tube pitch to diameter(p/Do) and the ratio of heated coil tube pitch to particle size(p/dp). The experimental results are as follows. 1) Mean heat transfer coefficients increases according to the increasing ratio of heated coil tube pitch to diameter(p/Do). 2) The Increasing rates of mean Nusselt numbers are more greater in the case of p/Do=1.58 than p/Do=4.75. 3) Mean Nusselt number can be expressed by the following equation, $Nu_{mean}=C\;Re^m\;Pr_g^{0.4}(p/dp)^n$.

• Korean Chemical Engineering Research
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• v.43 no.4
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• pp.525-530
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• 2005

The erosion rate of water wall tube has been measured and discussed in a commercial circulating fluidized bed combustor (200 ton steam/hr, $4.97{\times}9.90{\times}28.98m\;height$). Tube thickness was measured with ultrasonic method. Severe tube erosion rate was observed in the splash region on all waterwalls including wingwalls. The tube erosion rate increased after an initial decrease as height from the distributor increased. The difference of erosion rate among wing walls was found due to unbalanced distribution of gas and solid flow rates. The erosion rate of the wing wall increased as location of the wing wall became closer to the center of combustor crosssection.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.4
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• pp.971-980
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• 1990

본 연구에서는 실험적으로 2상 밀폐 직사각형 열사이폰 루프에 대하여 안정성 에 주된 영향을 줄수 있는 변수들, 즉 루프 경사각도, 작동유체의 유동현상을 관찰하 고 작동유체의 온도변동과 류프의 전열성능을 측정하여 열사이폰이 안정하게 작동하는 범위를 종합적으로 조사해 보았다.

• Solar Energy
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• v.15 no.1
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• pp.85-94
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• 1995

This research has been proceeded over the potential core region(H/B=2) of two-dimensional impinging air jet sytem, in which square rods(width of 6 mm) has been set up in front of heating surface in order to increase heat transfer. The objective of this research was to investigate the characteristics of heat transfer and air flow, in eases of the clearance from rods to heating surface(C=1, 2, 4, 6 mm) and the pitch between each rods(P=30, 40, 50 mm) changed. And this research compared the above with the experimentation without rods. As result, heat transfer performance was best under the condition of C=1mm, in case clearance changed, and there was no serious difference in the effect of heat transfer augmentation in the case of pitch of rods changed.

• Solar Energy
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• v.18 no.2
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• pp.145-152
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• 1998

In this experimental study, for obtaining the data to be used in the increased recover rate of waste heat from the recirculated sand, the furan foundry sand were used as the fluidized particle in the fluidized bed in which the smooth, spiral and finned tubes($Do={\varphi}12.7$) were horizontally installed and used as the heat-transfer tubes. The heat transfer experiments were performed in the conditions of water Reynolds number of inside tubes in the range of 4,000 to 18,000 and particle Reynolds number of outside tube in the range of 0.8 to 7.5. The heat-transfer coefficients(ho) increase as the higher inside temperature of the fluidized bed and the maximum heat-transfer coefficients can be obtained in the range of 3.5 to 5.5 of particle Reynolds number in the all tubes. The maximum Nu numbers of smooth, spiral and finned tubes are figured as about 1:1.5:3 in order even if the ratios show little different as the temperatures of bed.

• Journal of Power System Engineering
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• v.13 no.5
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• pp.5-10
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• 2009

본 연구에서는 판형열교환기를 적용한 청수제조장치의 성능에 대하여 연구를 수행하였다. 판형열교환기는 자체의 높은 열전달 성능과 컴펙트한 장점으로 하여 산업에서 점차 널리 사용되고 있다. 또한 사용, 유지보수가 다른 종류의 열교환기에 비하여 편리하여 유연성 있게 사용할 수 있다. 본 실험에서는 세브론 각도가 60도인 전열판을 사용하였으며 이젝터의 작동으로 열교환기를 장착하고 있는 탱크내부에 진공압력을 유지함으로서 내부유체가 $51^{\circ}C{\sim}57^{\circ}C$에서 증발현상이 발생하는 것을 확인하였다. 또한 수치해석적 방법을 통하여 복잡하며 좁은 세브론전열판으로 이루어진 유로내의 유동특성을 파악할 수 있었다.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.1199-1204
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• 2006

The pressure drop and heat transfer coefficient were measured at room temperature in CFB heat exchanger with multiple vertical tubes. Also the circulation rate of solid particles was measured. The theoretical model for predicting heat transfer coefficient using the solid flowrate was developed in this study. The model predictions were compared with the measured heat transfer coefficient to show relatively good agreement.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.05a
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• pp.91.1-91.1
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• 2004

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.27 no.3
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• pp.284-296
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• 1998

• Solar Energy
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• v.13 no.2_3
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• pp.91-106
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• 1993

The purpose of this study was to investigate the enhancement of heat transfer coefficient in double pipe fluidized bed heat exchangers. The inner tube used a smooth tube and a finned tube equipped with longitudinal fins. The heat transfer coefficients between the heated tube and fluidized bed of alumina beads were calculated as a function of fluidized velocity in various particle sizes($d_p$=0.41, 0.54, 0.65, 0.77mm) and static bed heights($H_o$=50, 100, 150, 200, 250mm). The coefficient for finned tube is higher than for smooth tube. And the maximum increasing rate is 7.8 times in smooth tube and 12.9 times in finned tube.