Experimental optimization of an absorption-compression heat pump with wet compression for large temperature glide industrial applications

The present work demonstrates the experimental optimization of a single-stage compression-absorption heat pump system for an application with a large temperature glide on the heat sink side using wet compression. The primary focus is weak solution injection to optimize the compressor discharge temperature and absorber heat sink temperature glide optimizations and their effect. With constant heat sink and source inlet temperatures at 60 °C and a mass flow rate of 0.25 kg/s, preliminary results show that the system delivers 50 kW of heating load and 26 kW of cooling load, respectively. Increasing the heat sink temperature glide between 28 °C and 48 °C reduces Lorenz COP and improves system efficiency. A weak solution mass flow rate of 0.015–0.25 kg/s with a minimum absorber pressure of 15 bar is recommended to achieve a higher heat sink temperature glide. Increasing the weak solution injection flow rate from 0 to 0.03 kg/s decreases the compressor discharge temperature from 139 °C to 122 °C, with a constant 0.0015 kg/s injection directed to the bearing and shaft seal. The results also highlight differences in the overall heat transfer coefficients and heat flux between absorbers 1 and 2. Absorber 1, operating in bubble mode, performs better with a maximum heat transfer coefficient of 1.39 kW/m²K compared to absorber 2, which operates in falling film mode. The system's performance and behavior are comprehensively evaluated, providing a foundation for future improvements and advancements in oil-free absorption-compression heat pump technology.