WASTE HEAT RECOVERY OF NAVAL SHIP GAS TURBINE EXHAUST USING TRANSCRITICAL CO2 CYCLE

Abstract

ABSTRACT Common power cycles discard a large portion of useful energy into the environment via exhaust gases. Through the use of cascade bottoming cycles, this wasted energy may be utilized for power generation. Heat transfer between cycles occurs through a waste heat recovery heat exchanger. To maximize heat exchange, a transcritical working fluid is used in the Rankine bottoming cycle to better match the heating curve of the sensible heat source. Carbon dioxide is selected as the working fluid because it possesses a relatively low critical temperature which makes it attractive for low temperature waste heat applications. In contrast to many other working fluids, carbon dioxide is inert, abundant, non-flammable, and presents negligible environmental impact. The purpose of this study is to quantify the performance of the transcritical bottoming cycle and the combined cycle as a whole by altering system parameters by using commercially available ‗EES‘ software to gain insight for future research in the field of waste heat recovery. This thesis also includes the economic analysis of system by calculating the cost of system power output annually. Parametric analysis and exergy analysis are conducted to examine the effects of thermodynamic parameters on the cycle performance and exergy destruction in each component. The thermodynamic parameters of the transcritical CO2 power cycle is optimized with exergy efficiency as an objective function by means ‗EES‘ software under the given waste heat condition. It is shown that the key thermodynamic parameters, such as turbine inlet pressure, turbine inlet temperature, environment temperature and exhaust temperature from naval ships gas turbine have significant effects on the performance of the transcritical CO2 power cycle and exergy destruction in each component.