Thermodynamic performance assessment of ammonia/ionic liquid based half-effect absorption refrigeration cycle

Abstract

The potential of ammonia/ionic liquids half-effect absorption refrigeration cycle (ARC) has been investigated. The thermodynamic model of the half-effect ARC and the property models of ammonia/ionic liquid working pairs have been established with verified accuracy. In addition, the thermodynamic and economic performance comparisons between the four ammonia/ionic liquid working pairs and ammonia/water in the half-effect ARC cycle are conducted. With coefficient of performance (COP) and solution circulation ratio as key performance indicators in this paper, the results reveal that, in general, the COP of the four ammonia/ionic liquid working pairs is higher than that of the ammonia/water, and there exists an optimum generation temperature for the cycle to achieve the highest COP. With the cooling capacity per unit UA, the cycle's economic performance is studied. Under the typical operating conditions, the COP of working pairs with [emim][BF4] has the highest value (0.342), followed by [dema][Ac] (0.330), [dmim][DMP] (0.300) and [emim][SCN] with the lowest value (0.293). And the cooling capacity per unit UA of ammonia/[emim][BF4] has the highest value. Moreover, compared to the other candidates, ammonia/[emim][BF4] performs best under most operating conditions and can be recommended as a reasonable working pair for the half-effect ARC.

Keywords

• Half-effect absorption refrigeration cycle
• Ammonia
• Ionic liquid
• Low-grade thermal source
• Thermodynamic performance