Operation optimization of an organic rankine cycle (ORC) heat recovery power plant

This paper presents a detailed analysis of an organic rankine cycle (ORC) heat recovery power plant using R134a as working fluid. Mathematical models for the expander, evaporator, air cooled condenser and pump are developed to evaluate and optimize the plant performance. Computer programs are developed based on proposed models and algorithms. The effects of controlled variables, including working fluid mass flow rate, air cooled condenser fan air mass flow rate, and expander inlet pressure, on the system thermal efficiency and system net power generation have been investigated. ROSENB optimization algorithm combining with penalty function method is proposed to search the optimal set of operating variables to maximize either the system net power generation or the system thermal efficiency. The optimization results reveal that the relationships between controlled variables (optimal relative working fluid mass flow rate, the optimal relative condenser fan air mass flow rate) and uncontrolled variables (the heat source temperature and the ambient dry bulb temperature) are near liner function for maximizing system net power generation and quadratic function for maximizing the system thermal efficiency.