Thermodynamic Optimization And Experimental Design Of A Novel Composition Adjusement Zeotropic Organic Rankine Cycle With Liquid-separation Condensation

Environmental problems caused by energy shortages and energy utilization have prompted the world’s energy structure to gradually shift to a new pattern dominated by renewable energy.Therefore,sustainable energy conversion and utilization technologies are urgently needed.The Organic Rankine Cycle(ORC)has received extensive attention from academia and industry because of its obvious advantages in the utilization of low-grade heat energy.However,the performance of ORC system degrades significantly under the off-design condition because it is significantly affected by environmental parameters.Therefore,it is of great significance to study the operation control strategies and optimization methods of ORC under the variable condition,which can improve the performance of the ORC system and accelerate the large-scale promotion of ORC technology.In order to improve the ORC performance under all operating conditions,A novel composition adjusement zeotropic ORC with liquid-separation condensation was proposed in this paper.The thermodynamic optimization and experimental design of novel ORC were carried out.(1)Analysis of heat matching between working fluid and heat source/sink in zeotropic ORC.Since the types and compositions of the working fluid directly affect the operating performance of the ORC system under the off-design condition.It is necessary to reveal the changing laws of the ORC performance with different working fluids and compositions under different heat source/sink conditions.In response to this problem,a thermodynamic analysis model of zeotropic ORC was established.The effects of ORC performance with working fluids and compositions under no heat source/sink,single heat source,and different heat source/sink conditions were studied.The law of the zeotropic ORC operating parameters and cycle performance was obtained.It is revealed that the working fluid composition is the key parameter that affects the performance of the ORC under variable heat source/sink parameters.The optimal composition changes significantly with the parameters of the heat source/sink.(2)Thermodynamic optimization of zeotropic ORC system.Considering that the the working fluid composition is one of the key parameters that affect the performance of ORC,the zeotropic working fluid composition can be reasonably thermally matched with the heat source/sink by optimizing.A thermodynamic analysis and optimization model of a zeotropic ORC system(AZORC)was established.Based on the genetic algorithm,the working fluid composition of the geothermal-driven AZORC under different conditions was optimized.By analyzing the influence of the optimal composition of AZORC,the change rule of the optimal working fluid composition with the working conditions was obtained.The advantages of the proposed AZORC system compared with the fixed-composition conditional ORC system(BZORC)in thermodynamic performance were verified.(3)Thermo-economic optimization of zeotropic ORC with working fluid composition adjustment.Integrating the thermodynamic advantages of ORC with variable-compositon and the advantages of enhanced heat transfer by liquid separation condensation,a novel composition adjusement zeotropic ORC with liquid-separation condensation(LCAZORC)was proposed.A sequential method and genetic algorithm(GA)were applied to conduct the thermodynamic optimization,component design,and thermo-economic optimization of the proposed ORC.The proposed compostion adjustment unit was simulated based on Aspen Plus.The component design and operating performance of the geothermally driven LCAZORC had been optimized.The advantages of coupling of heat transfer enhancement and composition tuning in a component of LCAZORC system was revealed.The effectiveness of the proposed composition adjusement system was verified.(4)Design and construction of ORC experimental installation with composition adjustment.In order to verify the feasibility and effectiveness of the proposed composition adjusement ORC system,an experimental test installation for the composition adjusement ORC was designed.Designed and selected the components of the experimental installation for the composition adjusement ORC.It provided a guarantee for the new composition adjustable system proposed by the practice experimental test and the reconstruction of the system.