Study on falling film generation heat transfer of lithium bromide solution in vertical tubes

2009 ◽  
Vol 18 (3) ◽  
pp. 241-245 ◽  
Author(s):  
Chengming Shi ◽  
Canjun Xu ◽  
Huili Hu ◽  
Yang Ying
Keyword(s):  
Heat Transfer ◽  
Lithium Bromide ◽  
Falling Film ◽  
Bromide Solution ◽  
Lithium Bromide Solution ◽  
Vertical Tubes

Modeling an Integral Dual Solar/Gas Fired Generator for a Water-Lithium Bromide Absorption Chiller

1999 ◽  
Author(s):  
Jiming Cao ◽  
Richard N. Christensen
Keyword(s):  
Heat Transfer ◽  
Natural Gas ◽  
Solar Energy ◽  
Current Flow ◽  
Lithium Bromide ◽  
Absorption Chiller ◽  
Transfer Resistance ◽  
Subcooled Liquid ◽  
Bromide Solution ◽  
Lithium Bromide Solution

Abstract This paper presents a design process for a dual solar/gas fired generator. A generator fired by solar energy and/or natural gas for a water-lithium bromide absorption chiller of 25 refrigeration tons (RT) was modeled. The natural gas is considered as the backup heat when the solar energy is unavailable or insufficient. The flue gas and the water-lithium bromide solution are in co-current flow, while the solar fluid and the water-lithium bromide solution are in counter-current flow. Fifty fluted tubes were installed vertically between two concentric cylindrical tubes. A solid ceramic insert was used to enhance heat transfer on the gas side that is considered as having the dominant heat transfer resistance. The burner is installed inside the smaller cylindrical tube. The solar fluid from the solar collector enters the generator through the fluted tubes while the water-lithium bromide mixture flows in the annular channel around the fluted tubes as a subcooled liquid. The generator is divided into two regions according to the heat transfer mechanism: subcooled liquid region and desorption region. In this model, a simultaneous solar and gas fired desorption process was investigated. The amount of makeup heat needed from natural gas was determined as a function of the solar fluid flow rate. Local temperature profiles were predicted by the model.

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