Characterization, optimization and feasibility analysis of a novel high-temperature heat pump with large temperature differentials for combined cooling and heating supply

High-temperature heat pumps (HTHPs) experience significant performance degradation when operating under large temperature differentials, which undermines their competitiveness in practical applications. To address these challenges, a novel HTHP system designed for combined cooling and heating (CCH) applications with large temperature differences is proposed. An in-depth characterization, optimization and feasibility analysis of the improved system is conducted, leveraging three HTHP cycles as a control and incorporating an advanced CCH performance indicator. The study demonstrates the following key findings: (1) The proposed system exhibits the highest heating COP, moderate operational stability and heating capacity when operating under large temperature differentials. (2) Under the set specified CCH conditions, the system attains a first-place operational COP of 2.623, surpassing the second-place system by 8.06 % and the lowest-performing system by 20.79 %. This performance level aligns with the heating performance achievable using a 50 °C waste heat source. (3) Through the selection of refrigerant pairs, R152a/R1233zd(E) is found to have relatively optimal CCH performance, with a 5.15 % improvement compared to the initially used R1234ze(E)/R1234ze(Z). (4) Compared to gas boilers, the system presents remarkable economic advantages, achieving payback within five years. Over its lifecycle, the system reduces operational costs by 11.70 % (Beijing), 20.45 % (Guangzhou), and 28.70 % (Singapore), respectively. (5) The CO2 emission level of the system under the set CCH mode reaches that of gas boilers, effectively mitigating the environmental drawbacks associated with HTHPs operating under large temperature differentials.