Perfomance Improvement And Application Analysis Of Kalina Cycles Based On Waste Heat Of Marine Diesel Engine

According to the energy utilization of marine two-stroke low-speed diesel engines,the situation of the utilization of waste heat of marine diesel engines is briefly introduced.Since the exhaust temperature of the marine diesel engine is in the range of medium and low temperature(below 300 ° C),it is easy to cause the problem that the conventional Rankine cycle will receive lower thermal performance.The Kalina cycle can effectively recover the medium and low temperature waste heat,and has practical application in the production process.Therefore,it is necessary to study the application scheme of Kalina cycle in the waste heat recovery of marine diesel engine.Therefore,this paper completed the following work:(1)According to the range of the exhaust temperature of the marine diesel engine,the performance comparison of different Kalina cycle systems is performed.This includes determining initial conditions and the establishment of system performance parameters.The physical properties of the ammonia mixture are calculated by means of MATLAB calling REFPROP.According to the system composition and structural characteristics of different Kalina cycles,the determination method of each state point parameter of each system and the calculation model of each component are obtained,and the calculation of each system is performed.Finally,the advantages and disadvantages of each system are compared and analyzed from the perspective of thermodynamic performance and economic efficiency.(2)This paper analyzes ammonia concentration,expander expansion ratio and system cold source temperature on the thermodynamic performance and economic performance of the more complex KCS1 system in the Kalina cycle.Thus the variation of system performance parameters can be concluded.(3)This paper briefly introduces the method of residual pressure energy recovery in industrial production process.According to the characteristics of Kalina cycle,the hydraulic turbine and two-phase expander are used respectively to utilize the residual pressure of the lean ammonia solution at the outlet of the separator.According to both of characteristics of the work process,the power capability has been calculated and the influence that different parameters in the system to power capability are analyzed.The research shows that the hydraulic turbine has a slightly higher power capability than the two-phase expander’s,but the two-phase expander is more suitable for the change of the ammonia concentration in the system.(4)According to the parameters of 6S50ME-C8.2 marine diesel engine and combined with the characteristics of the waste heat utilization system,the KCS34 system that the high-temperature regenerator after expander is used as the WHR system of this type diesel engine.The two-phase expander is utilized to recover the residual pressure energy.According to the actual situation,the initial conditions and assumptions of the calculation were reconsidered,and the evaluation indexes of the system were added.Finally,the effects of different working conditions and cold source temperature on the system performance were discussed.