Thermodynamical Analysis of the Distillation Column for Targeting Minimum Energy in Ammonia–Water Absorption Refrigeration Cycle

Abstract

In this study, a comprehensive method to optimize distillation columns in ammonia–water absorption refrigeration, power, and cogeneration cycles is introduced. The novelty of this work lies in a comprehensive analysis of the distillation column's thermal performance and the introduction of a new design framework that maximizes heat integration. Key findings include the critical role of the solution heat exchanger, especially at lower generation and evaporation temperatures. Using a saturated liquid or two‐phase feed can achieve up to 80% efficiency at a feed composition of 0.3. Moreover, in the results, the substantial potential for improving the coefficient of performance (COP) through strategic design is highlighted. Notably, minimizing the pinch point temperature difference to 0 °C can boost the COP by 6%, while optimal feed placement can increase it by 9%. Incorporating feed preconditioning and side exchangers can lead to a 22% COP enhancement, indicating the significance of heat integration to the distillation column. In this study, a graphic guideline for selecting cycles that can achieve a minimum of 10% COP improvement without introducing unnecessary complexity is delivered and it suggests that distillation columns can be simplified by using a combination of separators, heaters, and coolers in certain cases.