The Study And Design Of Organic Rankine Cycle In The Waste Heat Recovery System Of The Marine Diesel Engine

As the one of main force in the transportation industry,the ship is the transportation tool which consumes huge energy.With the continuous rise in international crude oil prices,improving fuel economy has become the most concerned topic in the whole shipping industry.The ship’s high energy consumption not only makes the cost,but also brings serious environmental problems.A series of international shipbuilding new rules and new standards are developed to implement by the International Maritime Organization(IMO)recently,especially the influence of ship’s energy efficiency design index EEDI.Keeping the ship with the marine diesel engine waste heat utilization system(WHR)is one of the effective ways to improve energy efficiency design index(EEDI)of a new ship.Conventional refrigerant water rankine cycle thermodynamic performance is low and heat exchanger flue gas acid dew point and corrosion when the marine diesel engine exhaust gas temperature in the low temperature range(under 300 ℃),which results the conventional WHR system can only recovery the energy of main exhaust temperature over 175 ℃.The range of recovery energy is low.However,Organic Rankine Cycle(ORC)technology can recovery diesel engine exhaust gas waste heat in low temperature effectively,and expand the scope of temperature to recovery the exhaust,so it has theoretical and practical significance in application of ORC in Ship Research and design in WHR system.The main contents of this plan are as follows:1、With the 6S50ME diesel engine of MAN company as the basis to analysis the loss and toward of the energy.Based on the thermal balance principle,it calculate the energy dissipation of diesel engines in details,such as the heat taken away from diesel exhaust,and the heat taken away from the water of air cooler and jacket.Bringing the modulated MAN6S50ME diesel engine parameter into the calculation,it work out the waste heat utilization potential value of each part,and then analyzing the "quality" and "quantity" of each residual heat,which makes the foundation for adopting various projects to recovery waste heat with different qualities.2.Research the basic principles of Organic Rankine Cycle(ORC),lists the selection criteria and restrictions of application conditions,and selected nine kinds of refrigerant as alternative refrigerants.For the ORC steady state thermal cycle diagram,list the key components of various thermodynamic calculation formula and simulating calculation was carried out by EXCLE Ref Prop software called R245fa,analyze the simulating result the comprehensive performance of R245ca the best,the best evaporation temperature 90-100 ℃.3.Distribute each part of the waste heat utilization potential of diesel engine reasonably,use R245fa to design various projects of recovering the waste heat of the MAN6S50ME with low speed marine diesel engine,formate four scheme and gives the computational formula to the whole performance of ship’s WHR system.After the simulating calculation,it comes out that scheme three is the best in energy efficiency,scheme four with good comprehensive properties and scheme two is more simple and reliable than scheme one.4.Propose selection standards of ORC heat exchanger,analyze the advantages and disadvantages of the plate heat exchanger,shell and tube heat exchanger and finned tube heat exchanger,summarized that three kinds of heat transfers’ coefficient of heat transfer and structure parameters can meet the demand of the best resistance loss under given conditions.Using the heat exchanger structure to design evaporator,preheater and condenser which are used in ORC recycle respective.5.According to the selection criteria proposed by ORC expander,the radial turbine design formulas are given for the one-dimensional gas,written using EXCLE program,the R245fa and the design condition,design runoff ORC steam turbine under different input parameters,prediction of single stage centrifugal ORC turbine isentropic efficiency and other key parameters.6,At last,through the selection and design of the heat exchanger,expansion machine,pump,tank,pipe valves,etc.The preliminary,it has the formation of design scheme of waste heat recovery ORC experiment platform for ship.The full text of ORC in marine WHR system application,design and performance evaluation was systematically described.Using reasonable way can improve the thermal efficiency of diesel engine about 6%and generation power is about 1200kW.Additionally can supply ship with needed water,so recovery effect is obvious.