Performance evaluation of a low-grade power generation system with CO₂ transcritical power cycles

Globally, there are vast amounts of low-grade heat sources from industrial waste and renewables that can be converted into electricity through advanced thermodynamic power cycles and appropriate working fluids. In terms of the working fluid's environmental impact, temperature match of cycle heat processes and system compactness, CO₂ transcritical power cycles (T-CO₂) were deemed more applicable for low-grade heat to power conversion. However, the system thermal efficiency of a T-CO₂ requires further improvement. Subsequently, a test rig of the small-scale power generation system with T-CO₂ power cycles was developed with essential connected components. These include a plate thermal coil CO₂ supercritical heater, a CO₂ transcritical turbine, a plate recuperator, an air-cooled finned-tube CO₂ condenser and a CO₂ liquid pump. Various preliminary test results from the system measurements are demonstrated in this paper. Meanwhile, the system model has been developed and applied to predict system performance at different operating conditions. The simulation results can therefore instruct further design and optimisation of system and components.