• 설비공학논문집
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• 제16권2호
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• pp.194-201
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• 2004

In the present study, the improvement of absorption characteristics on combined heat and mass transfer process in a falling film of a vertical absorber by change of geometric parameters were studied experimentally and analytically. The energy and diffusion equations are solved simultaneously to give the temperature and concentration variations at the liquid solution-refrigerant vapor interface and at the wall. Absorption behaviors of heat and mass transfer were analyzed through falling film of the LiBr aqueous solution contacted by refrigerant vapor in the absorber. Effects of film Reynolds number, geometric parameters by insert device (spring) and flow pattern on heat and mass transfer performances have been also investigated. Especially, effects of the flow pattern by geometric parameters have been considered to observe the total heat and mass transfer rates through falling film along the absorber. As a numerical and experimental result, maximum absorption rate was shown at the wave-flow by insert device (spring). The error ranges between experiment and analysis were from 5.8 to 12％ at Re$_{f}$ > 100.0.

• 대한기계학회논문집B
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• 제27권5호
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• pp.604-611
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• 2003

This study was concerned with the enhancement of mass transfer by surfactant added to the aqueous solution of LiBr. Different vertical inner tubes were tested with and without an additive of normal octyl alcohol. The test tubes were a bare tube, groove tube, corrugate tube and inserted spring tubes. The additive concentration of normal octyl alcohol as a surfactant is about 0.08mass%. The Sherwood number was measured as a function of film Reynolds number 20~200. The experimental results were compared with those which use no surfactant. The enhancement of mass transfer by Marangoni convection effect which was generated by addition of the surfactant is proved for each testing tube Especially, it is clarified that the tube with the spring has the highest enhancement effect. A correlation of the experimental mass transfer data for the bare, groove, corrugate and insert spring tubes results expressed as the form of Sh=cㆍ Re$_{f}$ $^{n}$ .

• Journal of Advanced Marine Engineering and Technology
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• 제28권8호
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• pp.1239-1250
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• 2004

This research was concerned with the enhancement of heat transfer by surfactant added to the aqueous solution of LiBr. Different vertical tubes were tested with and without an additive of normal octyl alcohol. The test tubes are a bare inner surface. a groove inner surface, a corrugated inner surface and a spring inserted inner surface tubes. The additive concentration was about 0.08 mass%. The heat transfer coefficient was measured as a function of the film Reynolds number in the range of 20~200. Experiments were carried out at higher cooling water temperature of $35^{\circ}C$ to simulate an air cooling condition for several kinds of absorber testing tubes. The experimental results were compared with and without surfactant. The enhancement of heat transfer by Marangoni convection effect which was generated by addition of the surfactant is observed in each test tube. Especially, it is clarified that the tube with an inserted spring has the highest enhancement effect.

• International Journal of Air-Conditioning and Refrigeration
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• 제8권2호
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• pp.1-10
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• 2000

This research is concerned with the enhancement of heat transfer by surfactant added to the aqueous solution of LiBr. Different vertical tubes were tested with and without an additive of normal octyl alcohol. The test tubes are a bare tube, a groove tube, a corrugated tube and a spring-inserted tube. The additive concentration is about 0.08 mass%. The heat transfer coefficient is measured as a function of the film Reynolds number in the range of 20~200. Experiments are carried out at higher cooling water temperature of $35^{\circ}C$to simulate an air cooling condition for several kinds of absorber testing tubes. The experimental results with and without surfactant are compared. The enhancement of heat transfer by Marangoni convection effect which is generated by addition of the surfactant is observed in each test tube. Especially, it is clarified that the tube with an spring-inserted has the enhancement effect.

• Journal of Advanced Marine Engineering and Technology
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• 제30권4호
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• pp.463-473
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• 2006

The effect of tube diameter on heat and mass transfer characteristics of absorber in absorption chiller/heater using LiBr solution as a working fluid has been investigated by both of numerical and experimental study to develop a high performance and compact absorber. The diameter of the heat exchanger tube inside absorber was changed from 15.88mm to 12.70mm and 9.52mm. In numerical study a model of vapor pressure drop inside tube absorber based on a commercial 20RT absorption chiller/heater was performed. The effect of tube diameter, longitudinal pitch, vapor Reynolds number, longitudinal pitch to diameter ratio on vapor pressure drop across the heat exchanger tube banks inside absorber have been investigated and found that vapor pressure drop decreases as tube diameter increases, longitudinal pitch increases, vapor Reynolds number decreases and longitudinal pitch to diameter ratio increases. In experimental study, a system includes a tube absorber, a generator, solution distribution system and cooling water system was set up. The experimental results shown that the overall heat transfer coefficient, mass transfer coefficient. Nusselt number and Sherwood number increase as solution flow rate increases. In both of study cases, the heat and mass transfer performance increases as tube diameter decreases. Among three different tube diameters the smallest tube diameter 9.52mm has highest heat and mass transfer performance.

• 한국응용과학기술학회지
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• 제29권2호
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• pp.278-285
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• 2012

낮은 농도와 높은 농도의 염 용액에서 Poly(styrene sulfonic acid)(PSSA) 겔의 팽윤도에 대한 이온 특성화 효과를 ${SO_3}^-$와 페닐 고리의 수소결합을 통하여 조사하였다. 낮은 농도에서 PSSA 수화 겔의 수축 정도는 ${SO_3}^-$와 물 사이의 수소 결합에 대한 음이온의 불안정화 영향 때문에 음이온에서는 $SCN^-$<$Br^-$<$Cl^-$<$F^-$의 순서를 따랐다. 재 팽윤은 계에서 특별한 상호 작용이 있을 때 높은 농도에서 관찰되었다. 반면 양이온에서 PSSA 겔의 수축은 $Li^+$<$Na^+$<$K^+$<$Ca^{+2}$ 순서를 따랐다. $Ca^{+2}$ 이온에서의 큰 수축 효과는 이가 양이온(+2)에 의한 PSSA 겔의 물리적 가교 때문에 나타난 것으로 보인다. 양이온에서의 수축은 ${SO_3}^-$와 양이온 사이의 상호작용 정도에 비례하였다. PSSA의 팽윤에 대한 이온 특성화 효과는 ${SO_3}^-$와 페닐 고리의 수화 수소결합에 대한 이온의 영향 정도, 양이온과 ${\pi}$ 전자의 상호작용, 소수성 상호작용, 그리고 분산력 등이 복합적으로 작용하여 나타난다고 볼 수 있다.