Energy and Exergy Analysis of a Lithium Bromide – Water (LiBr – H2O) Solar Absorption Refrigeration System

Abstract

Energy and environmental analysis establishes an important role in industrial performance due to the ease at which improvement processes are developed to increase production targets while minimizing the level of pollution and operating costs. Additionally, the exergy destruction analysis defines a clearly structured understanding related to the performance of the thermodynamic cycle. Exergy and energy analysis of the thermodynamic process is investigated based on advanced theories of thermal sciences in order to improve their energy efficiency and to evaluate the exergy destruction developed during their operation. Consequently, thermodynamic efficiency and total exergy destruction studies are used to define the thermodynamic interactions between mechanical devices and to establish the optimal behavior of refrigeration systems under specific operating conditions. This paper performs an energy and exergy analysis of a single effect absorption refrigeration system using a LiBr - H2O solution as working fluid and cooling water for the cycle, considering flat plate solar collectors as heat sources for the absorption refrigeration system. The solar field has been modeled by using a proposed model based on meteorological data, and the cycle is modeled in Aspen Plus® simulation environment, obtaining the thermodynamic properties necessary for the subsequent calculations. Afterwards, some indicators are calculated, such as the Coefficient of Performance (COP), exergy yield and exergy destruction, using Engineering Equation Solver (EES). Consequently, by using MATLAB®, it has been possible to determine the set of parametric variables and operating conditions where a better energy performance of the system can be obtained through optimization algorithms improving the COP from 0.7374 to 0.8097 according to the meteorological conditions of Colombia.