Enhanced thermal output from air-source cascade heat pumps configuration for steam generation

Steam generating heat pumps (SGHPs) present a promising solution for replacing coal-fired boilers and advancing industrial decarbonization by utilizing waste heat to produce high-temperature steam. This study proposes a novel air-source cascade steam generating heat pump (CSGHP) designed to address the challenge of sustaining high-temperature steam output. The system incorporates innovative design enhancements to effectively mitigate insufficient heat dissipation and temperature slip in the autocascade cycle condenser. A variable-condition model was developed for the CSGHP, along with a detailed operational framework to guide the optimization of critical parameters during system coupling. The feasibility and reliability of generating 170 °C steam using low-temperature air sources were comprehensively evaluated through thermodynamic, environmental, and economic analyses. Results demonstrate the robust adaptability of the CSGHP across a wide temperature range, enabling efficient steam production with heat sources ranging from -30 °C to 80 °C. At a heat source temperature of -30 °C and a steam output temperature of 170 °C, the system achieves a COP of 1.42 and a steam flow rate of 10,296.00 L/h. During extended operation in Beijing, the CSGHP maintained steam production exceeding 22,923.80 L/h with a COP consistently above 1.52. Furthermore, comparative analysis showed superior performance over conventional electric boilers in terms of CO 2 emission reduction and operational cost-effectiveness. This work provides theoretical guidance for expanding SGHP applications and advancing the development of high-temperature-lift heat pump systems. • Generates 170°C steam from -30∼80°C heat sources. • Novel system enables year-round stable operation in cold regions. • Addresses autocascade cycle condenser overheating issues. • Optimizes matching in cascade high/low-temperature cycles.