This paper proposes a cascaded recovery system for industrial blower exhaust heat based on a cascade heat pump, in which waste heat is first recovered by a heat exchanger and then further upgraded by the cascade heat pump to meet end-user demands. Thermodynamic and exergy models were developed according to the first and second laws of thermodynamics, and economic indicators were introduced. MATLAB simulations evaluated the effects of refrigerant combinations (R22/R123, R152a/R245fa, R134a/R142b, R152a/R134a, R134a/R134a), blower pressure ratio (1.1–1.8), low-temperature evaporation temperature (13–23 °C), intermediate temperature (46–68 °C), and compressor isentropic efficiency (0.60–0.95) on coefficient of performance (COP), specific heat-source energy consumption, and exergy efficiency. Results show that refrigerant pairing strongly affects performance, with R22/R123 achieving the highest COP (5.45) and lowest energy use. Higher exhaust and evaporation temperatures improved COP, while optimal intermediate temperature minimized power use for some refrigerants. Increasing compressor efficiency boosted COP by over 40%. Exergy analysis identified the high-temperature condenser and expansion valve as major loss points (30%–40%). This study identifies key parameters and optimization pathways for improving system performance, providing valuable theoretical and engineering guidance for the design, operation, and refrigerant selection of high-efficiency industrial waste heat recovery systems.

 

Blower waste heat; Cascade heat pump; Thermodynamic modeling; Performance analysis; Exergy efficiency; Economic analysis