COMPARISON OF WASTE HEAT RECOVERY SYSTEMS FOR THE REFITTING OF A CRUISE FERRY

During recent research activities carried out also in collaboration with leading industries, the authors have developed design and simulation models for the recovery of the exhaust thermal energy released from diesel engines. This previous experience is applied, in this paper, to an existing cruise ferry, whose propulsion system consists of two controllable pitch propellers driven, each one, by a couple of four stroke diesel engines. Starting from the available data on the current board systems, a proposal of refitting is presented, based on the comparison of six different waste heat recovery (WHR) plant solutions, optimized in relation to the peculiar requirements of the ship. The steam produced by the heat recovery steam generator (HRSG) can be used, depending on the selected configuration, to meet the on board steam needs and/or to contribute to the production of electric energy. The comparison of the proposed solutions, between them and with the simple originally available on board, is carried out taking into account not only the amount of thermal energy recovered and the consequent fuel saving, but also some other important aspects such as the sizes and weights of the WHR plant components and the related problems of installation on board.