Study On Thermodynamic And Thermo-economic Performance Of Solar CPC-KCS Hybrid System

Most of the existing research is about KCS integrated with concentrating collectors such as parabolic trough solar collector and nonconcentrating collectors like flat plate collector and evacuated tube collector.However,little research focuses on the KCS powered by compound parabolic concentrator?CPC?.Considering the merits of CPC such as no tracking device and convenient operation,a Kalina 11 cycle system which is directly powered by CPC,named as solar CPC-KCS hybrid system is studied as the research object by using the software EES and REFPROP9.0.Firstly,from the perspective of thermodynamics and thermoeconomics,energy,exergy and thermo-economic models in terms of?_th,?_exx and levelized energy cost?LEC?are established to estimate the system performance by changing the solar radiation,evaporating temperature and concentration of working fluid.And the results show that under the condition of lower X_b and higher X_r,the system has better performance.However,when T_e>416.15K,lower X_b is not beneficial to improve the cycle performance anymore.And with the increment of T_e,the?_th,?_ex and LEC of the hybrid system can be also improved a lot.But higher T_e has higher corresponding working pressure,considering the loading capacity of the components,T_e cannot exceed445.15K.Under the designed working condition,?_th is generally lower than?_ex,and according to the exergy analysis,CPC collectors is the component that takes the largest part of exergy loss in the system.Morever,it also contributes to the most investment cost of the whole cycle.Secondly,considering the corrosion problem of exhaust steam at the turbine exit,the dryness of exhaust steam x_r has been discussed.For the condition of x_r<0.9,adding a superheater before the turbine is aimed to improve the dryness of ammonia water.And a comparison between improved system and original system is also conducted.The result shows that whenT_e>421.15K,under the condition of X_b?0.7 and X_r?0.95,x_r is probably lower than 0.9,and there is a necessity of using a superheater.And the dryness of exhaust steam can be improved a lot by adding a superheater and then avoding the corrison problem.However,adding a superheater into the system can lead to not only a decrease of the system performoance but also a growth of capital investment.When T_e>424.15K,?_ex of the improved system is higher than the original system,and LEC of these two system are very close.Thus,adding a superheater into the system is a necessary and economic choice.Finally,the project chooses three kind of solar collectors that have similar heat collecting characteristic to actuate Kalina system.They are flat plate solar collector?FPCS?,evacuated tube solar collector?ETSC?and CPC collector,respectively.According to the comparison,the hybrid system powered by FPSC shows the worst performance.When T_e<358.15K,ETSC hybrid system shows a better performance than CPC-KCS system.However,when T_e exceeds 358.15K,CPC-KCS is the best choice to use solar energy to generate electricity.