Performance Analysis Of A Combined Dynamic Cycle Using Solar Energy And LNG Cold Energy

In order to solve the energy problem faced by our country,the government has put forward two strategic measures for energy development,one of which is to optimize the energy industry structure of our country and enhance the proportion of clean energy in primary energy consumption.In order to reduce the damage to the environment during energy use.Therefore,studying the utilization of LNG cold energy and solar energy is in line with the basic national conditions of our country’s gradual transformation to an energy-saving society,and has far-reaching social and strategic significance.This paper starts from the research status and practical application of LNG cold energy generation system.For improving the generation efficiency and energy recovery efficiency of LNG cold energy recovery process,the process of LNG cold energy utilization is deeply studied.At the same time,a new SCRB/Kalina combined cycle is proposed which utilizes solar energy and recovers LNG cold energy simultaneously.The thermodynamic properties of the circulating working fluid were analyzed in this paper.It was found that the components of the LNG,gasification temperature and pressure had a huge influence on the release of LNG cold energy and cold water.Meanwhile,the incompressibility of carbon dioxide and the characteristics of ammonia mixture during boiling can effectively improve the energy utilization of the system.Upon completion of the physical and mathematical models of the system,the first law efficiency and the second law efficiency of the system are 54.35%and 50.13%,respectively,which can produce a net power output of12.98 MW.LNG gasification pressure,heat source temperature and ammonia mass fraction have huge influence on thermodynamic performance and economic performance.Using genetic algorithm to optimize the thermodynamics and exergoeconomic of the proposed new power cycle,the corresponding operating points of the maximum first law of the system are:T₂₁=650℃、P₂=2195k Pa、P₁₂=3798k Pa、x=0.48,and the corresponding operating points of the second law efficiency are:T₂₁=550℃、P₂=2229k Pa、P₁₂=3949k Pa、x=0.48.The operating points corresponding to the minimum unit cost are:T₂₁=650℃、P₂=2087k Pa、P₁₂=3220k Pa、x=0.48.Finally,the grey box model is used to analyze the system.It is found that the heat exchanger is the main component of the exergy loss,accounting for more than 65%of the total exergy loss,and the exergy loss is the main reason for the increase of the system cost.Based on the research,the thermodynamic and exergoeconomic properties of the new combined power cycle are analyzed,which provides a theoretical basis for the model design and efficient operation of the LNG cold energy generation cycle system.