Thermo-Economic Evaluation of Maisotsenko-Desiccant Cooling Systems for Gas Turbine Power Plants

Abstract

With the everlasting increase in population, a huge surge in the electricity consumption has been recorded. Thus, power plants manufacturers and utility companies need to augment the plants performance to cope with these rising of energy demands. Turbine blade cooling is a vital procedure in gas turbine power plants due to the high turbine inlet temperatures achieved. The main objective of the thesis is to cool down the air bled from the compressor for turbine blade cooling, using Maisotesnko-desiccant cooling systems. This will reduce the amount of bled air and improve the efficiency. In this research, the performance of 50 MWe gas turbine power plants with three different configurations; a simple gas turbine, a gas turbine with an air bottoming cycle (GTABC) and intercooled, reheated and recuperated (IcRhRc) gas turbine integrated with the proposed cooling systems are investigated. Research results indicated that the GTABC yielded an increase in the overall efficiency from 42.57 % without cooling to 43.27%, to 43.54% and to 43.83% for the triple stage Maisotsenko-desiccant (TS-MD), triple stage precooling Maisotsenko-desiccant (TS-PMD) and triple stage extra cooling Maisotsenko-desiccant (TS-EMD), respectively. Furthermore, a maximum reduction in the fuel mass flow rate was observed from 2.713 kg/s to 2.653 kg/s in the TS-EMD system leading to a decrease in the carbon foot print which agrees with recent United Nations sustainability reports. The exergoeconomic results of the IcRhRc gas turbine exhibited a reduction in the exergy destruction rate from 44.86 MW without cooling to 43.34 MW after integrating TS-EMD cooling system. Consequently, the exergy efficiency has increased from 50.92% to 51.43%, to 51.63% and to 51.86% after incorporating TS-MD, TS-PMD and TS-EMD, respectively. Subsequently, the cost rate of exergy destruction has decreased from 924.2$/hr to 879.1$/hr after implementing the TS-EMD cooling system. Moreover, the investment cost flow rate has decreased from 101$/hr to 99.92$/hr after integrating the TS-EMD cooling system. The exergoeconomic factor and relative cost difference were also evaluated to assess each component for further performance improvement.