Optimization of Waste Heat Recovery on Cruise Ships using Dynamic Simulation

The shipping industry is currently facing tightening emission regulations and demands for more efficient cruise ships to demand shipyards to find solutions for increased efficiency and lower emissions. Cruise ships still largely use internal combustion engines using marine gas oil as a fuel source. These engines have large heat losses that could be utilized to increase efficiency. The largest part of the lost energy is in the exhaust gases, these can be recovered by boilers producing steam, there covery rate in these is limited by the fuel type and exhaust gas temperature. The second large source for waste heat is in high-temperature cooling water unlike the exhaust gas heat recovery, which is widely used on cruise ships there is large amounts of heat in the HT water being unutilized. The aim of this thesis was to investigate a waste heat recovery system utilizing HT water as its heat source to find both ways to improve the system and possible problems in the current system. The thesis uses a simulation model to investigate the different heat consumers in the system and the possibility to improve the overall heat recovery rate in the system. The simulation model was built in Apros dynamic simulation software to mimic an actual waste heat recovery system. The simulation model was built based on an existing waste heat recovery system and validated using measurement data from an existing ship. Different alternative configurations were investigated and the simulations showed possibilities to improve the heat recovery rate in different ways