Use of Exergy Analysis to Quantify the Effect of Lithium Bromide Concentration in an Absorption Chiller

Abstract

Absorption chillers present opportunities to utilize sustainable fuels in the production of chilled water. An assessment of the steam driven absorption chiller at the University of Idaho, was performed to quantify the current exergy destruction rates. Measurements of external processes and flows were used to create a mathematical model. Using engineering equation solver to analyze and identify the major sources of exergy destruction within the chiller. It was determined that the absorber, generator and condenser are the largest contribution to the exergy destruction at 30%, 31% and 28% of the respectively. The exergetic efficiency is found to be 16% with a Coefficient of performance (COP) of 0.65. Impacts of weak solution concentration of lithium bromide on the exergy destruction rates were evaluated using parametric studies. The studies reveled an optimum concentration that could be obtained by increasing the weak solution concentration from 56% to 58.8% a net decrease in 0.4% of the exergy destruction caused by the absorption chiller can be obtained. The 2.8% increase in lithium-bromide concentration decreases the exergy destruction primarily within the absorber with a decrease of 5.1%. This increase in concentration is shown to also decrease the maximum cooling capacity by 3% and increase the exergy destruction of the generator by 4.9%. The study also shows that the increase in concentration will change the internal temperatures by 3 to 7 • C. Conversely, reducing the weak solution concentration results is also shown to increase the exergetic destruction rates while also potentially increasing the cooling capacity.

Energy and Exergy Analysis of an Absorption and Mechanical System for a Dehumidification Unit in a Gelatin Factory

“…Other articles have discussed the necessity of the chemical exergy in evaluating the thermodynamic behavior of the cycle. These values have been determined in [ 21 ], where the error associated with considering (or not) the chemical exergy of the mixture was only significant in the absorber and generator [ 22 , 23 ]. One article has even compared all these methods, as proposed by Palacios et al [ 17 ], in which it was shown that the method of Oliveira-Junior and Le Goff [ 18 ], indeed, may be used to analyze the exergy behavior of a binary mixture.…”

Comparison the start-up time of the key parameters of aqua-ammonia and water–lithium bromide absorption chiller (AC) under different heat exchanger configurations

“…Nowadays, environmental concerns about ozone depletion and global warming, on the one hand, and surplus energy consumption, rising fuel prices, etc., on the other hand, have made the absorption chillers more attractive to researchers. Absorption chillers are very suitable tools for reducing electric energy consumption and recovering waste heat from industrial plants [1][2][3][4]. Simulations are way very important tools for researchers to predict the performance of absorption chillers at the dynamic level with low cost.…”

Analysis on the Performance of Steam Absorption Chiller at Various Operating Conditions

“…Mehyo et al determined the destruction and losses of exergy in system components under operating conditions by MATLAB® computer program and found that the efficiencies for cooling and heating applications have reached up to 0.295, 1.295 respectively [13]. Lake et al also proved that the absorber, generator and condenser are the largest contribution to exergy destruction using engineering equation solver [14].…”