Recovery of waste heat from engines: An AD view

Abstract

The Newcomen engine (1705) and the Watt engine (1769) are good examples of coupled and uncoupled designs. The Watt engine had an efficiency of about 3%, a shallow value when compared to engines of nowadays while resulting in a significant increase at those times. According to Axiomatic Design, Watt engine had a better performance than the Newcomen design due to its uncoupled nature. This work aims at applying the same reasoning to choose between new inventions designed for recovering waste heat from engines as to produce work. The most popular of those inventions are the organic Rankine cycle (ORC) and the Kalina cycle. Marine applications use those inventions to improve the efficiency of Diesel engines because the increase of weight of the recovery system does not affect power propulsion. A controversial regarding what system to develop occurred in scientific community as well as in the industry. The application of AD to those cycles classifies ORC as an uncoupled design and the Kalina cycle as a coupled design. Therefore, the ORC might be pondered for future development regarding energy efficiency.