Performance analysis of a novel dual exhaust mixed refrigerant heat pump with large temperature lift

The substantial demand for heat energy, ranging from 70 − 100°C in industrial and commercial sectors, presents a significant challenge when utilizing traditional air source heat pumps. The conventional single-stage air source heat pumps often struggle with low system efficiency and poor operating conditions when tasked with heating with large temperature lift. To address these issues, a novel dual exhaust mixed refrigerant heat pump cycle was proposed. By incorporating an intermediate pressure compression stage in parallel, the proposed system can achieve an optimal temperature match in the recuperator, and lead to a significant enhancement in the coefficient of performance (COP). Compared to a single stage mixed refrigerant heat pump cycle, the novel system improves the COP from 5.063 to 5.756, representing an increase of 13.68 %. Concurrently, the exergy loss proportion of the recuperator decreases from 18.8 % to 13.7 %. The proposed system consistently demonstrates superior COP and exergy efficiency, regardless of whether the ambient temperature is within the range of 0 °C to 20 °C or the outlet water temperatures between 80 °C to 100 °C are present. These findings provide theoretical guidance for enhancing the performance of high-temperature heat pumps with large temperature lift.