Parametric Study of a Supercritical CO2 Power Cycle for Waste Heat Recovery with Variation in Cold Temperature and Heat Source Temperature

EasyChair Preprint 3471

Abstract

A supercritical carbon dioxide (S-CO₂) power cycle is a promising development for waste heat recovery (WHR) because of its high efficiency despite its simplicity and compactness compared with a steam bottoming cycle. A simple recuperated S-CO₂ power cycle cannot fully utilize the waste heat because of the trade-off between heat recovery and thermal efficiency of the cycle. A split-cycle in which the working fluid is preheated by the recuperator and the heat source separately can be used to maximize the power output from a given waste heat source. In this study, the operating conditions of the split S-CO₂ power cycles for waste heat recovery from a gas turbine and an engine were studied to accommodate the temperature variation of the heat sink and the waste heat source. The results show that it is vital to increase the low pressure of the cycle along with a corresponding increase in the cooling temperature to keep the low-compression work near the critical point. The net power decreases by 6 to 9% for every 5 °C rise in the cooling temperature from 20 °C to 50 °C because of the decrease in heat recovery and thermal efficiency of the cycle. The effect of the heat-source temperature on the optimal low-pressure side is negligible, and the optimal high pressure of the cycle increases with a rise in the heat-source temperature. As the heat-source temperature increases in steps of 50 °C from 300 °C to 400 °C, the system efficiency increases by about 2% (absolute efficiency), and the net power significantly increases by 30 to 40%.

Keyphrases: Cold temperature, Split cycle, Supercritical CO2 (S-CO2) power cycle, Waste heat recovery, exhaust gas

@booklet{EasyChair:3471,
  author    = {Young Min Kim and Young Duk Lee and Kook Young Ahn},
  title     = {Parametric Study of a Supercritical CO2 Power Cycle for Waste Heat Recovery with Variation in Cold Temperature and Heat Source Temperature},
  howpublished = {EasyChair Preprint 3471},
  year      = {EasyChair, 2020}}