An advanced marine engine waste heat utilization scheme: Electricity-cooling cogeneration system integrated with heat storage device

Abstract The waste heat recovery technology is an effective means to cut down the consumption of fossil fuel by ships, which improves the energy efficiency but reduces the pollution emissions caused by marine diesel engines. Unlike previous simple cascade utilization of energy, this paper designs two evaporators for Organic Rankine cycle to make full use of exhaust heat and takes the heat from condenser as heat source to drive absorption refrigeration system for reducing heat loss. The thermodynamic models of integrated system, optimization program of genetic algorithm and evaluation modules of economy are established. From the selection of non-azeotropic mixtures, it can be aware of that cyclopentane/pentane is adaptable to the variable working conditions of ship. Meanwhile, the calculation results indicate that output power, thermal and exergy efficiency of this binary fluid are up to 2866 kW, 16.22% and 48.25% at 80% engine load. In view of the case that cooling capacity produced by refrigeration system cannot meet the demand, a heat storage device is used to reserve heat and supply the extra cooling energy. The effect analysis shows that the material with higher specific heat is more conform to the refrigeration target. However, from the economic point of view, the various evaluation indexes are improved notably with the support of heat storage device.