Design of an Electricity Generation Plant Utilizing Wasted Thermal Energy

Abstract

A combustion process, including the combustion of fossil and non-fossil-based fuels, will produce thermal energy. This energy can be converted into electrical energy utilizing a conventional Rankine cycle. However, there is still thermal energy left in the flue gas, characterized by a relatively high temperature of the flue gases. This energy is usually ignored and released into the atmosphere causing inefficient combustion. To increase combustion efficiency, the heat wasted from the flue gas cleaning unit can still be extracted using an adequate system. This article aims to obtain the best design of a system that utilized wasted heat to generate electricity using a thermodynamic system known as the organic Rankine cycle (ORC). Three working fluids of Hexane, R11, and R113 were used and simulated at the same operational conditions to get the optimum performance of the designed system. Performances were studied in terms of turbine output power and thermal efficiency. The results show that the Hexane working fluid produces higher turbine power compared to R11 and R113. Meanwhile, the temperatures and pressure do not greatly affect system efficiency, but the flow rate of the working fluid greatly affects the output power of the turbine. The simulation results show that the Hexane working fluid is the most suitable for use to recover the wasted heat of a combustion process included in the flue gases.