Theoretical analysis, experimental research, and industrial verification of ultra-high temperature heat pump heating system

To address the demand for high-temperature heat supply in industrial scenarios where recoverable waste heat is unavailable, this study designs and develops a coupled system by combining the cascaded air-source high-temperature heat pump (ASHTHP) and steam compression system (SC). The system is intended to replace conventional fossil-fuel boilers and significantly reduce energy consumption. Utilizing a cascaded cycle with R410A and R245fa, the system extracts low-grade heat from ambient air. This heat is then upgraded through the coupled steam compression system to deliver pressurized steam with a temperature up to 150 °C. Based on theoretical investigation, an enthalpy-difference test bench and a steam compressor test rig are established to evaluate the performance of the ASHTHP and SC under various operating conditions, respectively. Test results show that under an ambient temperature of 20 °C and an output steam temperature of 125 °C, the ASHTHP delivers coefficient of performance (COP) of 1.71. The SC stably produces 1.69 t/h high-temperature steam at an inlet temperature of 110 °C and an outlet temperature of 150 °C at 2400 rpm. The deviation between simulation and experimental results is within 4%, validating the accuracy and reliability of the model. The system has been successfully demonstrated at a pharmaceutical plant in Yinan, Shandong Province, China. Under an ambient temperature of approximately 30 °C and a steam outlet temperature of 150 °C, the coupled system achieves a COP of 1.65. These results demonstrate the system's strong economic benefits and engineering potential for replacing fossil-fuel boilers in industrial applications.