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Numerical Simulation of Solution Droplets and Falling Films in Horizontal Tube Absorbers
Phan Thanh-Tong,Lee Ho-Saeng,Yoon Jung-In,Kim Eun-Pil The Korean Society of Marine Engineering 2006 한국마린엔지니어링학회지 Vol.30 No.5
This paper presents a numerical simulation of the behavior of the LiBr solution droplets and falling films in horizontal tube banks of absorber. The model developed here accounts for the details of the droplets formation and impact process for absorption on horizontal tubes including the heat transfer from solution film to the tube wall. Especially. the characteristic of unsteady behavior of solution flow has been investigated. Flow visualization studies shown that the solution droplets and falling films have some of the complex characteristics. It is found that. with the numerical conditions similar to the operating condition of an actual absorption chiller/heater, the outlet solution temperature and heat flux from solution film to the tube wall have a stable periodic behavior with time. The solution droplets and falling films in horizontal tube banks of absorber is a periodic unsteady flow. The results from this model are compared with previous experimental observation taken with a high-speed digital video camera and shown good agreement.
Modeling of Pressure Drop for Water Vapor Flow across Tube Banks inside Horizontal Tube Absorber
Phan Thanh Tong,Yoon Jung-In,Kim Eun-Pil The Korean Society of Marine Engineering 2006 한국마린엔지니어링학회지 Vol.30 No.4
A model for a pressure drop of water vapor flow across tube banks in a horizontal tube absorber of an absorption chiller/heater using LiBr solution as a working fluid has been developed based on a commercial 20RT(70kW) absorption chiller/heater. The numerical results show that the characteristic of the pressure drop in the shell side of the horizontal tube absorber is completely different from that in a conventional shell and tube heat exchanger. Especially, solution film thickness has significant influence on the vapor pressure drop in the horizontal tube absorber. In addition, the effects by the tube diameters, the longitudinal pitch to diameter ratio, and Reynolds number of the vapor flow, on the vapor pressure drop have been studied to evaluate the compactness of tube absorber. It was found that the vapor pressure drop decreases as tube diameter increases, the longitudinal pitch to diameter ratio increases, and Reynolds number of the vapor flow decreases. A comparison of the present study results with well-established experimental and numerical results showed a good overall agreement.
Experimental Study on Heat and Mass Transfer in Abfsorber using Small Diameter Enhanced Tubes
Thanh Tong Phan,Ho-Saeng Lee,Gwang-Hoon Seong,Jung-In Yoon 한국마린엔지니어링학회 2006 한국마린엔지니어링학회 학술대회 논문집 Vol.2006 No.-
This article reports on the results of experimental study on the heat and mass transfer characteristics of a horizontal tube falling film absorber, which made by corrugated tubes and having small diameter tubes, using LiBr solution as a working fluid. Three different tube diameters of 15.88㎜, 12.70㎜ and 9.52㎜ are installed inside the absorber to investigate the effect of the tube diameter on the heat and mass transfer performance of the absorber. The experimental results show that the heat and mass fluxes increase as the solution flow rate and cooling water velocity increase and the inlet cooling water temperature decreases. At the experimental conditions, the heat and mass transfer coefficients of the corrugated tube are respectively higher than those of the bare tube from 11.9% ti 28.4% abd from 16.2% to 23.1%. The absorber shows better heat and mass transfer performance with smaller tube diameter.
Experimental Investigation of Heat Transfer in Absorber with Small Diameter Tube
Thanh Tong Phan,Choon-Geun Moon,Jae-Dol Kim,Jung-In Yoon 한국마린엔지니어링학회 2006 한국마린엔지니어링학회 학술대회 논문집 Vol.2006 No.-
The effect of tube diameter on heat transfer characteristics of absorber in absorption chiller/heater using LiBr solution as a working fluid has been investigated by experimental study to develop a high performance and compact absorber. A system includes a tube absorber, a generator, solution distribution system and cooling water system was set up. The diameter of the heat exchanger tube inside absorber was changed from 15.88㎜ to 12.7㎜ and 9.52㎜. The experimental results show that the heat transfer coefficient, Nusselt number and heat flux increase as solution flow rate and cooling water flow rate increase. The heat transfer performance increases as tube diameter decreases. Among three different tube diameters, the smallest tube diameter 9.52㎜ has highest heat transfer performance. A comparison of the heat transfer coefficient obtained by the present study with those of previous experimental results showed good overall agreement.
문춘근,Thanh-Tong Phan,방기석,윤정인 한국마린엔지니어링학회 2003 한국마린엔지니어링학회 학술대회 논문집 Vol.2003 No.-
Recently, the usage of an absorption chiller/heater is positively promoted in the viewpoint of unused energy application, the preservation of earth environment, and the settlement of unbalance demand between electric power and city gas. Using of the absorption chiller/heater which uses heat source energy as a driving power can not only reduce the electric power demand but also obtain the promotive effect of city gas demand. Absorption chiller/heater can utilize the unused energy of the life waste heat, the industry waste heat, the solar energy and the earth energy. These contribute to a energy saving. But the absorption chiller/heater has the demerit that the size of absorption chiller/heater is larger than the type of vapor compression on based same capacity. In this study, the experimental apparatus of an absorber is manufactured as a plate which is newly applied in an absorber. The characteristic heat/mass transfer is searched by the experimental method in the absorber of a plate. The absorption enhancement by surfactant in the absorber is examined closely through the experiment of heat and mass transfer characteristic to the quantitative and qualitative analysis.
이호생,성광훈,Phan Thanh Tong,윤정인 대한설비공학회 2006 설비공학 논문집 Vol.18 No.12
Experimental results for heat transfer characteristic and pressure gradient of hydrocarbon refrigerants(R-290, R-600a, R-1270) and HCFC refrigerant(R-22) during condensation inside horizontal double pipe heat exchangers are presented. The test sections which have one tube diameter of 12.70mm with 0.89mm, 9.52mm with 0.76mm, 6.35mm with 0.13 mm wall thickness are used for this investigation, respectively. The local condensing heat transfer coefficients of hydrocarbon refrigerants were higher than those of R-22. The average condensing heat transfer coefficient increased with the increase of the mass flux. It showed the higher values in hydrocarbon refrigerants than R-22. Hydrocarbon refrigerants have higher pressure drop than R-22 in 10.92mm, 8mm and 6.1mm inner diameters. These results from the investigation can be used in the design of heat transfer exchangers using hydrocarbons as the refrigerant for the air-conditioning systems.
Study on High Performance and Compact Absorber Using Small Diameter Heat Exchanger Tube
Yoon Jung-In,Phan Thanh Tong,Moon Choon-Geun,Kim Eun-Pil,Kim Jae-Dol,Kang Ki-Cheol The Korean Society of Marine Engineering 2006 한국마린엔지니어링학회지 Vol.30 No.4
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.