A novel generator–condenser heat exchange coupled auto-cascade absorption refrigeration cycle for low-grade heat utilization

To improve the thermodynamic performance of auto-cascade absorption refrigeration (ACAR) systems driven by low-grade heat, a generator–condenser heat exchange coupled cycle (GCX-ACAR) is proposed. It utilizes condensation heat from non-azeotropic refrigerant mixtures at higher temperatures, enabling more effective internal heat recovery over a wider operating range. A thermodynamic model of the GCX-ACAR cycle is developed and validated, and the effects of key operating parameters, including high-side pressure, generation temperature, and absorption temperature, are systematically investigated. The results show that the new cycle significantly reduces generator heat input while maintaining comparable refrigeration capacity. A minimum refrigeration temperature of −105°C is achieved and the maximum coefficient of performance (COP) reaches 0.04, representing an improvement of 45%-114% compared with the conventional ACAR cycle. The enhanced performance is mainly attributed to the efficient utilization of temperature glide during the condensation process of non-azeotropic mixtures and the cascade recovery of condensation and rectification heat. The proposed cycle provides a promising pathway for improving the efficiency of low-grade heat-driven refrigeration systems and shows potential applications in LNG precooling and hydrogen liquefaction processes.