Mechanical Engineering ETDs

Publication Date



Common power cycles discard a large portion of useful energy into the environment via exhaust gasses. Through the use of cascade bottoming cycles, this wasted exergy may be utilized for power generation and hot water production. Heat transfer between cycles occurs through a heat exchanger. To maximize heat exchanger effectiveness, 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 topping cycle to be used is an air Brayton cycle with methane as the fuel source. 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 to gain insight for future research in the field of waste heat recovery.


Heat recovery, Waste heat, Heat exchangers, Carbon dioxide, Rankine cycle.

Degree Name

Mechanical Engineering

Level of Degree


Department Name

Mechanical Engineering

First Committee Member (Chair)

Razani, Arsalan

Second Committee Member

Truman, Randall

Third Committee Member

Poroseva, Svetlana

Document Type