Development of dynamic simulation tool for transcritical carbon dioxide Rankine cycle

Abstract

Waste heat recovery has recently drawn intense research attention; however utilization of low-temperature heat still have many bottlenecks When direct heat source power cycle is applied to low-temperature waste heat the scale effect will greatly affect the system efficiency a proper working fluid and cycle configuration are essential to improve the efficiency Supercritical CO2 power cycle is one of the solutions The results suggest that for a system in kWe scale transcritical CO2 Rankine cycle with regenerator (TCRC-r) is the most efficient and the overall system efficiency will up to 2 times higher than the transcritical Brayton cycle with regenerator (TCBC-r) under specific conditions Further in this research Matlab/Simulink model was built to analyze the operating characteristics of the transcritical CO2 Rankine cycle with a dynamic heat source and explore the problems of system efficiency and power generation changes under the unstable supply of low-grade industrial waste heat The research results show that the cycle with regenerator can reduce the fluctuation of system characteristics that TCRC-r is a relatively stable cycle configuration Although the addition of regenerator has significant benefits for power generation and overall efficiency the delay of TCRC-r is more affected by the period of heat source meaning that the reaction time is less affected by the addition of a regenerator than the heat source period In addition the discontinuous characteristics of the TCRC-r system are caused by the change in the properties of CO2 in the process of transforming from the coexisting state of liquid and vapor to the liquid state

Date of Award	2021
Original language	English
Supervisor	Ming-Hsun Wu (Supervisor)