Research On Ocean Thermal Energy Conversion System And Its Heat Exchanger And Ejector

With rapid economic growth,China has become the world's largest consumer of resources.With the increase of energy demand,environmental issues should be taken into account.Therefore,in response to the call of "improving the utilization of resources and building a recycling system",industries are actively developing clean energy and expanding energy saving production.Among them,ocean thermal energy as a promising renewable energy has attracted widespread attention.As its core,Ocean Thermal Energy Conversion(OTEC)system has great potential in alleviating energy crisis.The specific research contents of this paper are as follows:Firstly,introduce the distribution of ocean thermal energy and the research progress of OTEC,discuss the heat exchanger classification and its application status in OTEC project,found ASPEN suitable for heat exchanger process design and dynamic simulation,and summarize the ejector's effect on OTEC system and the key factors affecting the ejector's performance.Then,carry out thermodynamic modeling,calculation and engineering check of the 50 kW R134a/R717 Organic Rankine Cycle(ORC),propose the 2D/3D ORC prototype scheme design with cooling and heating source control module,use ASPEN EDR to design dry heat exchanger,flooded heat exchanger,herringbone corrugated plate heat exchanger,compare the heat transfer performance of these heat exchangers,select the optimal structure and conduct HYSYS dynamic simulation analysis,discuss the effects of heat source temperature,cold source temperature,evaporation pressure and condensation pressure on heat transfer performance and thermal efficiency of the system.Secondly,put forward a new OTEC system with two ejectors using ammonia-water,establish thermodynamic model of the system,introduce the principle of supersonic ammonia ejector and design its structure,use adaptive meshing method and set import and export pressure boundary conditions of the 2D axisymmetric ejector,simulate the effects of the primary flow pressure(Pp),secondary flow pressure(Ps),back pressure(Pb),area ratio(AR)and nozzle exit location(NXP)on fluid characteristics,ejector performance and system thermal efficiency of the supersonic ejector.Thirdly,add solar heat collector to new OTEC system to improve heat source temperature and working conditions,further study the fluid flow characteristics in supersonic ejector,and analyze the effects of Pp,Ps and Pb on ejector performance and thermal efficiency of the system under this working condition.Finally,summarize the research contents and conclusions of this paper,and put forward the shortcomings and the need for improvement.