Analysis of single and double effect LiBr-H2O absorption cooling systems to meet the cooling requirements of surface ships

Abstract

As technology advances, the cooling loads of future surface ship electronic systems are increasing. Increasing cooling loads and the need for efficient energy use on board necessitate studies on cooling systems. This study demonstrates the feasibility of using single and double-effect LiBr-H2O absorption cooling systems on surface ships facing increasing cooling demands. The proposed systems utilize exhaust waste heat from gas turbines and diesel generators as a heat source. In the study, the combustion analysis of the exhaust gases is performed, and the waste heat that can be used for the absorption system generator supply is calculated for each speed stage for the gas turbine and each load condition for the diesel generator. Thermodynamic analysis of the system is conducted based on the surface ship's seasonal air and sea temperatures and average port and sailing hours over the ship's life cycle. Under these conditions, the energy obtained from the absorption cooling system on the simulated surface ship is used to reduce the ship generator load. Using the single effect LiBr-H2O absorption cooling system designed for the diesel generator reduces the load on the diesel generator, saving 20.2 tons in port, 7.4 tons underway, and 27.6 tons per year (1.83 %). The double effect LiBr-H2O absorption cooling system designed for the gas turbine saves 104.1 tons (6.92 %) of fuel for the diesel generator and 131.7 tons per year (8.75 %) for all systems. It was discovered that integrating the two systems on board can reduce 417.9 tons of CO2 emissions. It is also observed that an average of 894.1 kW of excess cooling power can be obtained, sufficient to meet the future cooling needs of the ship. This study confirms that the proposed cooling system is feasible and effective in meeting surface ships' increasing cooling demands.