Pinch Point Analysis of Air Cooler in sCO₂ Brayton Cycle Operating Over Ambient Temperature Range

Supercritical CO₂ Brayton Power cycle is getting commercially attractive for power generation due to its numerous advantages like zero water discharge, compactness, low environmental emission and potential to reach high thermal efficiency. A typical recuperated sCO₂ closed cycle consists of three heat exchangers (main heat exchanger, cooler and recuperator) and two turbomachinery (sCO₂ turbine and sCO₂ compressor). The cooler using ambient air for cooling is the focus of this study. Steady state air cooler model is set up to study the effect of air cooler size on cycle efficiency. The effect of change in ambient air temperature on air cooler pinch point for different air cooler sizes is analyzed using transient air cooler model. The simulation is setup for design of approximately 100MWe sCO₂ cycle with operating temperature of 700° C and pressure of 250 barA. Transient calculations are done using LMS AMESim. LMS AMESim is Siemens PLM commercially available software. This work thus serves as a framework to develop a design basis for air cooler in sCO₂ cycle as a function of transient operating conditions.