Study on the off-design performance of supercritical carbon dioxide power cycle for waste heat recovery of gas turbine

Abstract

The off-design performance of partial heating carbon dioxide power cycle driven by the waste heat of gas turbine is quantitatively analyzed in this paper. Firstly, multi-objective optimization is carried out from the perspective of thermodynamics and economics to determine the cycle parameters in design phase. The heat exchanger and turbomachinery are preliminarily designed based on the optimization results. Then, the performance of partial heating cycle under off-design conditions is investigated considering variable flue gas parameters and ambient temperature. The results indicate that the net power output would increase by 0.62 MW on average as the mass flow rate of flue gas increases by 5 kg/s. For every 10 °C increase in flue gas inlet temperature, the net output power will increase by 0.29 MW. However, the system exergy efficiency first increases then decreases as the mass flow rate of flue gas increases. The net power output and system exergy efficiency show descending tendency as ambient temperature increases. In summary, the regulation of cycle maximum pressure should be highlighted in response to the variation of flue gas parameters while the adjustment of cycle minimum pressure should be emphasized in response to the variation of ambient temperature.