(384b) Optimization of Series and Parallel Flow Configurations of Vapor Absorption Chiller

Increased energy demand with reduced emissions is the main challenge of the present world. This purpose can be fulfilled either by efficiency improvement or by utilizing alternative energy resources or fuels. Efficiency of the plant may be improved not only by optimizing its design and operation but also by utilizing its waste heat. Vapor absorption chillers (VAC) can utilize the low quality energy as compared to the conventional vapor compression cycles (VCC) which require electricity for compression. In addition to the use of low grade energy, other benefits of VAC over VCC includes the use of safe work fluids, low maintenance cost and low noise pollution. However, the major issue with VAC is its low efficiency. Therefore, the efficiency improvement is of significant importance and it can be achieved by optimizing the various process configurations of the cycle. In this work, exergy analysis (exergy efficiency) is used to indicate the performance of the VAC instead of conventional energy analysis (coefficient of performance) approach. Both the series and parallel flow configurations have been considered. Various operating parameters have been optimized for both configurations. The thermodynamic model was developed in MATLAB using the best available correlations for state properties and vapor-liquid equilibrium. A global optimization algorithm such as Genetic Algorithm has been used to optimize the operating conditions. Significant improvement in the performance of the VAC has been shown in terms of exergy efficiency. The effect of weather conditions and the used of various types of heating sources have also been considered.