PERFORMANCE OPTIMIZATION OF SUPERCRITICAL CO2 GAS HEATER IN A BIOMASS-CO2 POWER GENERATION SYSTEM

Abstract

A comprehensive computational fluid dynamics (CFD) simulation model was developed in the current research to simulate a shell-and-tube supercritical CO₂ gas heater used in a biomass-CO₂ power generation system. The model was based on the actual design of the heat exchanger and relevant operational parameters. The simulation model was validated using manufacturer operational data and empirical correlations before being utilized to evaluate the performance of the heat exchanger and its related system under various operating conditions and heat exchanger designs. The results of the simulation demonstrate that the heating capacity of the heat exchanger can be increased differently by increasing the flue gas temperature, flue gas mass flow rate, and CO₂ mass flow rate. Furthermore, there is an optimal CO₂ pressure ratio that can improve the system's thermal efficiency. Decreasing the distance between hot fluid pipe inlet and cold fluid outlet ports, as well as hot fluid pipe outlet and cold fluid inlet ports, can effectively enhance the heating capacity of the shell-and-tube heat exchanger and its associated system. In quantity, with the new heat exchanger design, the heating capacity exhibits maximumly 9.2% average improvement, while the associated system thermal efficiency can have an average 6% enhancement with varied flue gas mass flow rates. Based on the CFD simulation outcomes, recommendations for enhancing the heat exchanger designs and system controls have been identified.