Enlarged temperature lift of hybrid compression-absorption heat transformer via deep thermal coupling

Highlights: • A novel high-temperature heat pump for local waste heat recovery. • Thermally coupled compression and absorption sub-cycles for large temperature lift. • Experimental study of a 35 kW prototype for validation of the proposed cycle. • Prototype COP of 1.81 with a maximum temperature lift of 54 °C. The energy level mismatch between heat sources and industry users has posed a huge barrier for the wide application of local waste heat recovery, which cannot be efficiently addressed by traditional options due to the limited temperature lift. To fill this gap, a hybrid heat transformer is proposed to achieve large temperature lift via deep thermal coupling between compression and absorption sub-cycles. Firstly, simulation shows that 42.1 kW heat output (at 100 °C) is provided with the costs of 20.0 kW electricity and 67.4 kW waste heat (at 45 °C), resulting in a COP of 2.15 and a large temperature lift of 55 °C. Secondly, an experimental prototype was established for performance validation, which stably upgraded the waste heat from 47–51 °C to 99–102 °C with an overall COP of 1.81. Further investigation shows that the proposed system is quite flexible with waste heat source temperatures of 30–60 °C and output temperatures of 90–115 °C. Such an effective heat transformer with large temperature lift could be promoted for the efficient utilization of low-grade waste heat, and contribute to the industrial decarbonization.