Combined Cycle Inlet Air Cooling by Cold Thermal Storage: Aeroderivative vs. Heavy Duty GT Comparison

An assessment of energetic performance achievable by GT inlet air cooling through cold thermal storage is presented. Results have been obtained by a numerical code specifically developed to model the whole system behavior all over a year. Some cases with hot climatic condition have been compared and discussed in order to enlighten performance differences due to GT characteristics and possible enhancement strategies for different configurations. An existing 127 MWe combined cycle power plant with a twin GT configuration was assumed as a reference case. Two heavy-duty units with different technology levels have been compared with an advanced aero-derivative model, in the range of 40 MW power output. Aero-derivative unit provided a much better performance than the more advanced heavy-duty model; this was strictly related to the higher sensitivity to inlet air temperature of the aero derivative unit. The comparison between the two heavy-duty GTs has clearly shown that a high specific power is needed to obtain cost-effective solutions for inlet air cooling systems. The analysis for the considered GT units was then extended also to a plant configuration including an inlet air supercharging system. The boost fan head has been selected in order to only compensate all inlet pressure losses, i.e. inlet duct, filters and air coils pressure drops.