• Clean Technology
• /
• v.11 no.4
• /
• pp.181-188
• /
• 2005

Developed is the new gas-solid flow ball valve where air injection purging concept is applied for the control and the reduction of particle fouling. CFD analyses are conducted for investigating the interaction between gas-sold and air injection streams and the fouling phenomena in valve, and the analysis results are reflected in the design of valve geometry and air injection condition. Through the actual tests on designed ball valve, the present valve is shown to be superior in fouling reduction.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.4 no.4
• /
• pp.289-298
• /
• 1992

Fouling is "a major unsolved" area in heat transfer research. Currently, fouling researches are performed in every directions-fundamental aspects, modeling and cumulating experimental data. In this study, an attempt was made to extend the knowledge in enhanced tube fouling. The Kern-Seaton fouling model which was originally proposed for smooth tube fouling was extended to repeated rib tubes. Key parameters-mass transfer coefficient and wall shear stress-were modeled for repeated rib tubes. Some critical points related with the enhanced tube fouling-uncertainties in the mass transfer rate, wall shear stress modeling, deformation of roughness shape during fouling-were discussed, and some quantitative evaluations were made.

• Journal of Energy Engineering
• /
• v.4 no.1
• /
• pp.59-66
• /
• 1995

본 연구에서는 액체 유동층 열교환기의 수직관내에 유리알 (직경 3.0mm, 비중 2.54) 이 물과 함께 흐를 때 압력 손실, 열전달 계수 및 화울링 계수를 측정하였다. 실험 결과 유리알은 1.0 m/s 이하의 낮은 유속에서 열전달을 증진시켰고 실험범위 내에서 열전달 계수는 유속 및 고체의 흐름양에 관계없이 거의 일정하였다. 압력 손실은 고체의 흐름양이 증가할수록 급격히 증가하였다. 실험 결과를 토대로 압력손실 및 열전달 계수를 예측할 수 있는 상관식을 개발하였다. 유리알 유동층 흐름은 화울링 조절에 효과적인 것으로 일어나지 않았고 이미 화울링이 심하게 일어난 때에도 유리알은 효과적으로 산화철을 제거할 수 있음을 알 수 있었다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
• /
• 1995.05a
• /
• pp.207-212
• /
• 1995

본 연구에서는 발전소 응축기를 시뮬레이션 할 수 있는 프로그램을 개발하였다. 관 내외 측 열전달계수의 계산에는 기존 상관식들과 응축 모델을 사용하였고 $\varepsilon$-NTU 방법을 사용하여 응축기를 해석하였다. 실제 응축기를 모사하기 위하여 관다발 보정계수 및 화울링 계수도 도입하였다. 이 프로그램을 사용하여 기존 평관을 대체할 전열촉진관의 형상을 도출하였다. 시뮬레이션 결과 전열촉진관을 사용하면 증기 응축 온도를 6 - 8 $^{\circ}C$ 정도 낮출 수 있음을 알 수 있었다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.7 no.3
• /
• pp.450-460
• /
• 1995

A modified circulating fluidized bed heat exchanger under severe fouling condition is developed. The effects of fouling deposits on the performance of a heat exchanger are investigated. The principle and operating characteristics of a circulating fluidized bed heat exchanger are dicussed. A modified circulating fluidized bed heat exchanger shows more stable operating than the other circulating fluidized bed heat exchanger. The characteristics of self cleaning and heat transfer enhancement of a circulating fluidized bed heat exchanger are studied. The movement of spherical particles in a tube is visualized and heat transfer enhancement and scale reduction mechanism by particles are investigated.

• Proceedings of the KSME Conference
• /
• 2004.04a
• /
• pp.1582-1588
• /
• 2004

The present experimental study aimed to investigate the feasibility of physical water treatment (PWT) devices using catalytic materials to mitigation of crystalization fouling. Two PWT devices having different shape and material were used. The results from microscopic observation and SEM photographs demonstrate that the crystal structure of $CaCO_3$ is Argonite type without water treatment while Calcite type with water treatment, which clearly shows the feasibility of PWT techinque using catalytic materials to mitigate crystalization fouling. For 500 ppm solution, the fouling resistance decreased up to about 23% due to physical water treatment using catalytic materials. The results also reveal that if two more techniques are used simultaneously the additional effects could be expected.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.7
• /
• pp.31-41
• /
• 2016

A computer program that simulates electric utility steam condensers was developed, and used to investigate the effects of enhanced tubes in steam condensers. The replacement of smooth tubes with enhanced tubes reduces the steam condensing temperature, and increases the efficiency of the electric utility. Therefore, a significant amount of power may be reserved without any modification of the utility. Three enhanced tubes, corrugated, low fin with internal ribs, and low fin with internal 3-D roughness, were considered. The results showed that there is an optimal internal roughness height. Low fin tubes with a 3-D roughness were superior to the other enhanced geometries. This was attributed to longitudinal vortices generated between the circumferential dimples. An additional 0.5 MW~1.3 MW was possible when smooth tubes were replaced with enhanced tubes in the 600 MW electric utility condenser. The additional power increased with increasing coolant temperature. More investigations on fouling, corrosion, and mechanical properties will be necessary for actual applications of enhanced tubes in electric utility condensers.