Transient Thermodynamic Modeling of Air Cooler in Supercritical CO₂ Brayton Cycle for Solar Molten Salt Application

Supercritical carbon dioxide Brayton power cycle is getting commercially attractive for power generation due to numerous advantages like zero water usage, compactness, low environmental emission, and potential to reach high thermal efficiency at lower costs. A typical recuperated closed cycle consists of three heat exchangers (main heat exchanger, cooler, and recuperator) and two turbomachinery (turbine and compressor). Rapid changes in ambient temperature, operating loads, start-ups, and shutdowns affect the performance and operation of the turbomachinery and heat exchangers. The purpose of this research article is to study the thermodynamic parameters of the air cooler during transient operations by running dynamic simulations. Magnitude of change in carbon dioxide temperature due to change in air temperature is calculated. The simulation is a setup by having a steady-state design of 100 MWe cycle with operating temperature of 700 °C and pressure of 250 bar. Dynamic simulations are done using lms amesim. Transients studied in this article include: (i) step variation, (ii) standard variation, and (iii) linear variation of air temperature. This study thus serves as a framework to develop a design and control basis governed by transient scenarios.