IMPACT OF THE USE OF INLET AIR COOLING AND EVAPORATIVE AFTER COOLING ON THE ENERGETIC- EXERGETIC- ENVIRONMENTAL PERFORMANCE OF COMBUSTION GAS TURBINES

In the Kingdom of Saudi Arabia peak demand of electric power occurs during the middle of the day in summer and is almost double the off peak demand. The demand profile is ill matched to the performance profile of combustion gas turbines as their power output suffers significantly at increased ambient temperature due to the reduced available combustion air mass flow rate. Introducing Brayton refrigeration cycle for inlet air cooling along with the evaporative after cooling of the compressor discharge in combustion turbines is very much capable of achieving a significant reduction in inlet air temperature close to 0 deg-C and increase in mass flow rate which in turn enhances the power output and thermal efficiency significantly and reduces the NOx emissions considerably. Therefore in the current proposal, a natural gas fuelled combustion gas turbine subjected to inlet air cooling and evaporative after cooling is proposed which can meet out the peak demand of electric power of the Kingdom at summer ambient conditions in an efficient and eco-friendly manner as it eliminates the use of CFCs for producing cooling and reduces the NOx emissions while maintaining a higher thermal efficiency of the plant. The performance of the proposed cycle will be assessed theoretically and compared with the simple cycle combustion gas turbines operated by the Saudi electric utility company in the Kingdom. The study is also aimed to develop the exergetic sustainability indicators in order to determine sustainability aspects of combustion gas turbine based power plant. To this effect, first a comprehensive exergy analysis will be carried out to identify the causes and locations of thermodynamic imperfection and then the exergetic sustainability indicators, viz; exergy efficiency, exergy destruction factor, environmental effect factor, and exergetic sustainability index will be calculated. The effects of several design parameters such as the compressor inlet air temperature, ambient relative humidity, extraction pressure ratio, and turbine inlet temperature on energetic, exergetic, and environmental performance of the cycle will be observed. The optimum values of all these design parameters will be determined based on the concept of minimum exergy destruction and NOx emissions. The results obtained through present research using the proposed combustion gas turbine cycle will contribute towards increasing the energy contribution of existing gas turbine plants operating in a region of hot and humid climates of the Kingdom of Saudi Arabia. The research findings will be published in the Journals of International repute and hence will fill the gap of the open literature related to the proposed technology.