| Summary: | 碩士 === 國立臺北科技大學 === 化學工程研究所 === 101 === This study presents the thermodynamic analysis and thermoeconomic optimization of double-effect (parallel-type and series-type) lithium bromide (LiBr) absorption chillers. The mathematical model of double-effect LiBr absorption chillers is first established based on mass balance relations, energy balance relations, and constitutive state equations of each heat exchanger unit. Then, this study analyzes the thermodynamic properties of the double-effect absorption chiller, and calculates the irreversibility and energy loss of each unit. The effects of the coefficient of performance (COP) and exergy efficiency are investigated.
This study conducts the optimum design of the double-effect absorption chiller using a thermoeconomic method, known as the structural method. This method not only takes the thermodynamic considerations into account but also considers the economic optimization. The advantage of using the structural method for thermoeconomic optimization is that the various elements of the system can be optimized on their own. A simple equation to calculate the optimum area of each heat exchanger can be derived by introducing the coefficient of structural bond (CSB). The effects of important design parameters of the system (solution circulation ratio, LiBr concentration and distribution ratio) on the coefficient of performance (COP), exergy efficiency, irreversibility and total annual cost are investigated. Simulation results show that the total annual cost and the COP are improved after the optimization. The condition of energy loss depends on the annual operation time so that the exergy efficiency is improved for an increasing annual operation time.
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