Thermoeconomic Optimization of a LiBr/H2O Absorption Chiller Using Structural Method

Abstract

The optimization strategy for absorption chiller systems is generally based on thermodynamic analysis. However, the optimum, so obtained, does not always guarantee the economic optimum. In this regard, the thermoeconomics that combines the thermodynamic principles with economic parameters plays a vital role for achieving the cost effectiveness of these systems. In this paper, this technique is applied to optimize a single-effect LiBr/H2O absorption chiller system for air-conditioning applications aiming at achieving the minimum product cost. This optimization methodology is based on the relative interdependence between component irreversibility and the total system irreversibility. This relationship, known as structural coefficient, is used to evaluate the economic cost of the product of the system. The use of structural coefficient eliminates complex numerical procedures, and the optimization is achieved by sequential local optimization of the subsystems of the system. The analysis reveals that the capital cost of the optimum configuration is increased by about 33.3% from the base case, however, the additional cost is well compensated by reduced fuel cost. This is possible because of reduction of plant irreversibilities by about 47.2%.