Impact of Transients on Supercritical Co2 Compressor

Supercritical CO2 Brayton power cycle (sCO2) is getting attention due to the advantages of low emission to the environment, high efficiency with low costs and compactness when compared with Helium Brayton and steam power cycle. Each sCO2 power cycle consists of heat exchangers (main heat exchanger, cooler and recuperator) and the two turbo machinery parts (compressor, turbine). One of the most important components is the compressor. The changing of the CO2 properties near the critical point may affect the cooler and compressor. To reduce operating costs and increase the cycle efficiency and net power it is necessary to understand the behavior of the connection between cooler and the compressor. To avoid any issues related to durability and operating conditions of the power cycle, transient conditions need to be considered.

In this research, the transient simulation of the air cooler will be presented. The boundary conditions of the simulation are 100MWe net power, turbine inlet temperature 700℃, and Compressor outlet pressure 250bar in the steady-state. The transient simulation is performed using the commercial LMS AMESim software. For transient simulations, different temperature variations such as linear and standard steps are considered. The detailed description of the transient behavior according to the results will be presented. The results show the positive/negative effects of different temperature variations depending on ambient conditions.