In this study a novel frost-free air-source heat pump (FASHP) system

which uses the waste heat of a screw compressor for auxiliary desorption

was proposed. A mathematical model of FASHP with waste heat desorption was developed

and the accuracy of this model was verified experimentally. A theoretical analysis was conducted concerning the influence of ambient temperature

relative humidity

air temperature

and flow rate on the desorption of the system. The results show that the ratio of the waste heat that the system can use for desorption to the total energy required for desorption could reach 0.61. The coefficient of performance (COP) was affected by the air temperature and humidity

but less affected by the temperature and mass flow of the desorption air. As the ambient temperature increased and the relative humidity decreased to the working condition at 7 °C/70%

the COP reached 2.52. The COP of the novel FASHP system increased by 10% compared to the original system. It was proved that this system can run efficiently and continuously under low-temperature and high-humidity environmental conditions