Energy and exergy analysis of pebble bed thermal energy storage system for diesel engine exhaust

Abstract

In the present work, a pebble bed thermal energy storage (PBTES) system is developed to utilize the waste energy from engine exhaust. The developed PBTES is integrated with an electric dynamometer coupled stationary Diesel engine for experimental investigation. The engine performance is compared with and without integration of the PBTES system. The 60-75% of energy can be stored in the fabricated system during the charging process at various load conditions. It is found that nearly 11-15% of engine fuel energy can be saved using this storage system considering the charging process. Heat recovery/discharging from PBTES shows that 6-8.5% of fuel primary energy can be saved. The system combined (engine+PBTES) efficiency varies from 11-38% at different load conditions. The highest exergy saved is obtained as 3.32% when a 3 kW load is applied. The developed system can be easily used for domestic or industrial use space heating or hot fluid requirements.