Thermodynamic Analysis of an Evaporative Inlet Air Cooled Combined Cycle for Marine Application

The integration of inlet air cooling to gas turbine based power utilities is a well accepted practice as this modification to the utility delivers superior utility performance. However, application of inlet-air cooling to drive turbines and specifically to marine mobility sector is rare in literature. Marine vessels are generally propelled by diesel engines, however large marine vessels specifically cruise ships and high speed naval vessels may have requirements of higher speeds and on-board power requirements which can fulfilled by gas turbine driving the propellers while on-board power needs can be met by steam turbine power generated from gas turbine exhaust heat. Such gas-steam combined cycles have the potential to become popular for high capacity marine vessels. The choice of gas turbine based combined cycle power plant for marine vessels in comparison to diesel engine powered vessel is also superior due to lower emission from the former. Higher ambient temperatures are known to negatively affect gas turbine and hence also marine combined cycle performance. The present article discusses the prospects of using an evaporative inlet air cooled combined cycle as a prime mover for marine application. A parametric study of the effect of compressor pressure ratio, turbine inlet temperature, ambient relative humidity and ambient temperature on energy, exergy and emission performance of combined cycle used in marine application has been carried out. Evaporative inlet cooling integrated to cooled gas-turbine based combined-cycle has been observed to improve the power output by 10.25% and efficiency by 1.55%. This improvement has been observed to be higher at higher ambient temperature and lower ambient relative humidity. Inlet air cooling has also observed to improve emission performance with lower NO_X and CO emission. The overall cycle exergy destruction has also been observed to reduce due to the addition of inlet air cooling to a gas turbine propelled/powered based combined cycle.