Study On Utilization Of Fuel Cold Energy In Cargo Hold Of Large LNG Powered Container Ships

Aim at two problems exist in large LNG powered container ships:one is waste of fuel cold energy;secondly,the power consumption of refrigerated containers is large.In this study,a comprehensive utilization system of LNG cold energy is designed,which mainly uses LNG cold energy in the cargo hold of ships to cool refrigerated containers.The world’s first and largest LNG powered container ship（CMA CGM JACQUES SAADE）capable of carrying 23,000 TEUs is selected as typical ship.Firstly,the size of the cargo hold using LNG cold energy is designed and the structure is modeled.LNG cold energy utilization system of is designed,combined with the cold energy released by the ship during sailing and the cold load of ship cargo hold under different working conditions,different combination schemes of the number of high temperature and low temperature cargo holds under different working conditions are preliminary designed.Simulation tool Aspen HYSYS is used for modeling and simulation calculation of the whole system,which verifies the feasibility of various combination schemes and obtains the initial simulation data.System exergy efficiency and cold energy utilization efficiency are established,the sensitivity analysis function of Aspen HYSYS is used to investigate the relationship between the flow rate of node A-2 and the exergy efficiency of heat exchanger LNG-2,and the optimal flow rate of node A-2 corresponding to the exergy efficiency of heat exchanger reached the maximum under different ship working conditions,so as to complete system preliminary optimization.On that basis,for the goal that reduce exergy loss of the system and improve exergy efficiency of the system,the parameters of the ship’s cargo hold system and other cold energy utilization units are optimized,the optimal operating parameters of the system are determined,and realize the optimization of the whole system.Based on the final optimization results and simulation software,exergy efficiency and cold energy utilization efficiency of different combination schemes are calculated.The maximum exergy efficiency of the system is 33.98%,and the maximum cold energy utilization efficiency is 87.09%.Finally,according to the characteristics of such ship’s routes and the number of refrigerated containers loaded in different ports,combination schemes of the number of low temperature and high temperature cargo holds between neighboring ports are selected for the whole route,so as to get the average exergy efficiency and cold energy utilization efficiency of the system on the whole route,the maximum average cold energy utilization efficiency is 76.44%,the maximum average exergy efficiency is31.63%.Calculate the total power consumed by refrigerated containers on the whole voyage before and after using LNG cold energy.Up to 1.01×10⁷ k W·h of electricity can be saved,approximately 1.71×10⁶ kg of LNG fuel consumption can be reduced,and5.13×10⁶ kg of CO₂ emissions can be reduced on the whole route.In conclusion,the comprehensive utilization system of LNG cold energy proposed in this study not only provides a new way for the utilization of LNG cold energy on ships.It promotes the diversified development of LNG cold energy utilization technology in ships,but also promotes the development of green ships.