A study on the application of the absorption type refrigeration system using exhaust gas waste heat of ship to the ship was carried out.
There is an unusual climate all over the world, and global warming is the main cause. There are various discussions on the idea that global warming is the cause of greenhouse gas, but there is a close correlation between the increase of greenhouse gas and the increase of global temperature. Efforts are being made to reduce greenhouse gas emissions globally as the awareness of greenhouse gases and global warming increases.
In the case of ships, the waste heat recovery system can be operated to improve efficiency and reduce greenhouse gas emissions. And confirmed the effect of increasing energy efficiency of ship and reduction of greenhouse gas through A Study on the Ship’s Thermal Efficiency Improvement by the ORC Power Generation System by Temperature Difference between Exhaust Heat and Sea Water.
We considered additional efficiency improvement method after the ORC power generation system using exhaust gas waste heat. The absorption refrigeration system using waste heat was constructed, and the optimization method and the application of the ship were carried out.
A double effect absorption refrigeration system was designed using the HYSYS process design program and simulations were conducted to check the coefficient of performance and refrigeration capacity. As a result of simulation by inputting arbitrary temperature, pressure, and flow rate to the designed system, the results were obtained with a coefficient of performance of 0.48 and a freezing capacity of 185.5kW. The working fluid of the system was ammonia and water.
In order to optimize the system, the temperature of the exhaust gas supplied to the generator, the flow rate of the working fluid supplied to the generator, and the temperature of the cooling seawater supplied to the condenser were selected as parameters. The simulation results show that each parameter is changed and it affects the coefficient of performance. Then, simulation was performed by applying a combination of three parameters. Through the optimization process, the grade coefficient of performance could be improved to 0.58. For reference, the refrigeration capacity of 73kW was obtained.
The optimized absorption refrigeration system was applied to the BOG re-liquefaction system of the LPG carrier. The BOG re-liquefaction system of the LPG carrier was simplified by using HYSYS, and the refrigeration load was used in the BOG cooling process. As a result, energy savings of 16.5kW were confirmed.
Through this study, we confirmed the efficiency improvement after the ORC power generation system using exhaust gas waste heat. This study is expected to be useful for improving the energy efficiency of ship in industrial field.