Waste heat recovery from a diesel engine using shell and tube heat exchanger

• Diesel engine exhaust contains 38% energy which can be used to produce extra power.
• Optimum pressure of fluid exists for maximum power which was 30 bar for this study.
• The optimum pressure at 25%, 83%, 100% loads were 2, 20 and 30 bar, respectively.
• Extra 24% power gained with optimized heat exchangers using water as working fluid.
• Parallel heat exchangers showed better performance than series up to 30 bar.

Exhaust heat from diesel engines can be an important heat source to provide additional power using a separate Rankine Cycle. In this study, experiments were conducted using water as the working fluid to estimate the exhaust waste heat obtainable from a diesel engine using two available heat exchangers purchased from the marketplace. An additional power of 16% was found. As these heat exchangers were not specifically designed for this application, attempts were then made to improve the overall performance of the exhaust heat recovery system by optimizing the design of the heat exchangers. The working fluid pressure and the orientation of heat exchangers were also optimized. After optimization, the additional power increased from 16% to 23.7%.