• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.11 no.5
• /
• pp.570-578
• /
• 1999

An experimental study has been performed on heat and mass transfer in a falling film absorber with a strong lithium bromide solution in small-sized household absorption chiller/heater. Components were concentrically arranged in a cylindrical form. from the center, low temperature generator, absorber and evaporator. This arrangement of helical-typed heat exchangers allows to make the machine much more compact than conventional one. Experimental measurements were conducted with a helical absorber and the obtained data were compared with data in the literatures. The comparison revealed that the helical absorber tube provides a similar performance to existing tube bundle absorber in heat and mass transfer. As a result, the heat and mass transfer characteristics of helical type absorber showed the possibility of the reduction in size and weight of small] capacity absorption chiller/heater.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.24 no.11
• /
• pp.1428-1436
• /
• 2000

The absorption of vapor involves simultaneous heat and mass transfer in the vapor/liquid system. In this paper, a numerical study for vapor absorption process into LIBr-H$_2$O solution film flowing over helical absorber has been carried out. Axisymmetric cylindrical coordinate system was adopted to model the helical tube and the transport equations were solved by the finite volume method. The effects of operating conditions, such as the cooling water temperature. the system pressure, the film Reynolds number and the solution inlet concentration have been investigated in view of the absorption mass flux and the total absorption mass flux and the total absorption rate. The results for the temperature and concentration profiles, as well as the local absorption mass flux at the helical absorber are presented. It is shown that solution inlet concentration affected other than operation conditions for a mass flux.

• Proceedings of the KSME Conference
• /
• 2000.04b
• /
• pp.228-233
• /
• 2000

An experimental study has been performed regarding heat and mass transfer in a falling film absorber of domestic small-sized absorption chiller/heater. Components were concentrically arranged in cylindrical form : from the center, with a series of low temperature generator, absorber and evaporator. The arrangement of such helical-typed heat exchangers allows to make the system more compact as compared to conventional one. Experimental measurements were conducted with a helical absorber using $LiBr+LiI+LiNO_3+LiCl$ and LiBr solutions. As a result, the heat and mass flux performance of $LiBr+LiI+LiNO_3+LiCl$ solution shows the tendency of $2{\sim}5%$ increase. Therefore, $LiBr+LiI+LiNO_3+LiCl$ solution can be taken consideration into applying to small-sized absorption chiller/heater because of using without crystal through high concentration as 4wt% comparing with LiBr solution.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.28 no.1
• /
• pp.81-88
• /
• 2004

In this study, heat and mass transfer characteristics of five components solution (LiBr＋Lil＋LiNO$_3$＋LiCl＋$H_2O$) which could be substituted for commonly used LiBr solution are tested using a helical absorber. The arrangement of helical-typed heat exchangers allows to make the system more compact as compared to conventional one. The effects of experimental parameters, such as the solution flow rate, cooling water, solution temperature, solution concentration and surfactant have been investigated in view of the heat and mass transfer. The results of the experiment of heat and mass transfer performance show that five components solution should have 2％ higher concentration fur equal absorption capacity of LiBr solution. But considering that five components solution have higher solubility than LiBr solution about 4％ high concentration, five components solution could be applied to a small sized water cooled or air cooled absorption chiller/heater. The increase of heat and mass transfer coefficient by surfactant addition is about 25∼30％ and 23∼40％ respectively.

• 한국가스학회:학술대회논문집
• /
• 2000.09a
• /
• pp.232-243
• /
• 2000

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.16 no.1
• /
• pp.16-25
• /
• 2004

The flow and heat/mass transfer in the falling-film of a heat exchanger can be influenced by the motion of the surrounding refrigerant vapor. In this study, the effect of the vapor flow direction on the absorption heat transfer has been investigated for a falling-film helical coil which is frequently used as the absorber of ammonia/water absorption refrigerators. The experiments were carried out for different solution concentration. The heat and mass transfer performance was measured for both parallel and counter-current flow. The effect of vapor flow on the heat and mass transfer is found to be increased with decreasing solution concentration. In the experiments with low solution concentration, whose vapor specific volume is great, the counter-current flow of vapor resulted in uneven distribution of falling-film and reduced the heat transfer performance of the absorber. The direction of the vapor flow hardly affected the thermal performance as the solution concentration became stronger since the specific volume of the ammonia/water vapor was much smaller than that of the water vapor.