Exergy analyses and optimization of a single flash geothermal power plant combined with a trans-critical CO2 cycle using genetic algorithm and Nelder–Mead simplex method

Geothermal Energy

Science – Society – Technology

Table 1 Proposed system initial values (Wang et al. 2015)

Parameter definition	Symbol	Values
Dead state temperature	T₀	25 °C
Dead state Pressure	P₀	100 kPa
Geothermal fluid inlet temperature	T₁	170 °C
Geo-fluid mass flow	\(\dot{m}_{1}\)	10 kg/s
Geo-fluid inlet pressure	P₁	Saturated steam
Separator pressure	P₂	500 kPa
Steam turbine output pressure	P₅	20 kPa
CO₂ turbine inlet pressure	P₁₀	15,000 kPa
CO₂ condenser temperature	T_cond	30 °C
Turbine isentropic efficiency	η_tur	80%
Pump isentropic efficiency	η_pump	75%
Evaporator inlet–outlet difference temperature	ΔT_TTD	20 °C
Heat exchanger pinch point	ΔT_PP	5 °C