Over the last three decades,flexibility and controllability considerations for heat exchanger networks(HENs)have received great attention,respectively.However,they should be simultaneously incorporated in HEN synthesi...Over the last three decades,flexibility and controllability considerations for heat exchanger networks(HENs)have received great attention,respectively.However,they should be simultaneously incorporated in HEN synthesis to allow the economic performance to be achievable in a practical operating environment.This paper proposes a method for simultaneous synthesis of flexible and controllable HEN by considering their coupling.The key idea is to add the bypasses with optimized initial fractions and positions to explore such coupling,and consequently enabling HENs to be operated successfully over a range of disturbance variations.These are implemented by identifying and quantifying disturbance propagations,and then examining the sensitivity of bypasses to the entire HEN.In this way,the superstructurebased mixed integer non-linear programming(MINLP)with objective function of minimizing the total annual cost is formulated.A case study is used to demonstrate the application of the proposed method.Quantitative measures and dynamic simulation show the ability to provide the satisfactory flexibility and controllability of the obtained HEN.展开更多
Because of its paramount importance in the successful industrial control strategy of a given heat exchanger network(HEN),the control structure designs for providing appropriate manipulated variable(MV)and controlled v...Because of its paramount importance in the successful industrial control strategy of a given heat exchanger network(HEN),the control structure designs for providing appropriate manipulated variable(MV)and controlled variable pairings have received considerable attention.However,quite frequently HENs with such control structures face the problem of hard constraints,typically holding the HENs at less controlled operating space.So both the MV pairings and the above control pairings should be considered to design a control structure.This paper investigates the systematic incorporation of the two pairings,and presents a methodology for designing such two-tier control structure.This is developed based on the sequential strategy,coupling an indirect-tier with direct-tier control structure design,wherein the intention is realized in the former stage and the latter is implemented for further optimization.The MV identification and pairing are achieved through variations in heat load of heat exchangers to design the indirect-tier control structure.Then the direct-tier control structure is followed the relative gain array pairing rules.With the proposed methodology,on the one hand,it generates an explicit connection between the MV pairings and the HEN configuration,and the quantitative interaction measure is improved to avoid the multiple solutions to break the relationship among all the control pairings into individuals;on the other hand,a two-tier control structure reveals control potentials and control system design requirements,this may avoid complex and economically unfavourable control and HEN structures.The application of proposed framework is illustrated with two cases involving the dynamic simulation analysis,the quantitative assessment and the random test.展开更多
The traditional methods for synthesizing flexible heat exchanger networks(HENs)are not directly applicable to inter-plant HEN challenges,primarily due to the spread of system uncertainty across plants via intermedium ...The traditional methods for synthesizing flexible heat exchanger networks(HENs)are not directly applicable to inter-plant HEN challenges,primarily due to the spread of system uncertainty across plants via intermedium fluid circles.This complicates the synthesis process significantly.To tackle this issue,this study proposes a decomposed stepwise methodology to facilitate the flexible synthesis of the interplant HENs performing indirect heat integration.A decomposition strategy is proposed to divide the overall network into manageable sub-networks by dissecting the intermedium fluid circles.To address the variability in intermedium fluid temperatures,a temperature fluctuation analysis approach is developed and a heuristic rule is introduced to maintain the temperature feasibility of the intermedium fluids.To ensure adequate flexibility and cost-effectiveness of the designed networks,flexibility analysis and network retrofit steps are conducted through model-based optimization techniques.The efficacy of the method is demonstrated through two case studies,showing its potential in achieving the desired operational flexibility for inter-plant HENs.展开更多
Solid oxide fuel cell(SOFC)is an extremely promising technology for sustainable energy conversion and storage through highly efficient electrochemical reaction at high-temperature conditions.The existing studies commo...Solid oxide fuel cell(SOFC)is an extremely promising technology for sustainable energy conversion and storage through highly efficient electrochemical reaction at high-temperature conditions.The existing studies commonly address the final equilibrium state of the SOFC electrode reactions,giving less consideration to the micro kinetic of electrode reactions.In this paper,a kinetic model-based SOFC combined cycle power generation system is suggested to recover multiple waste heat,which includes a Kalina cycle(KC)as the bottom cycle and a Rankine cycle(RC)as the top cycle.In devneloping the proposed system,a novel kinetic model is presented for SOFC based on the microscopic mechanism of the oxygen reduction.A dynamic stochastic programming model is established to optimize the integrated system sequentially and simultaneously,with maximum power generation taken as the objective,depending on whether the SOFC system and the KC-RC system are simultaneously optimized.In sequential optimization,the output power of SOFC-KC-RC system is 320.56 kW and it is 415.04 kW using simultaneous optimization,achieving a 29.5%increase in power generation.Further comparison with the previous reports obtained by a thermodynamic model,this work leads to a 10.8%increase in power generation,showing the promising power production performance of the developed system.展开更多
基金Supported by the National Natural Science Foundation of China(21576036,21776035)
文摘Over the last three decades,flexibility and controllability considerations for heat exchanger networks(HENs)have received great attention,respectively.However,they should be simultaneously incorporated in HEN synthesis to allow the economic performance to be achievable in a practical operating environment.This paper proposes a method for simultaneous synthesis of flexible and controllable HEN by considering their coupling.The key idea is to add the bypasses with optimized initial fractions and positions to explore such coupling,and consequently enabling HENs to be operated successfully over a range of disturbance variations.These are implemented by identifying and quantifying disturbance propagations,and then examining the sensitivity of bypasses to the entire HEN.In this way,the superstructurebased mixed integer non-linear programming(MINLP)with objective function of minimizing the total annual cost is formulated.A case study is used to demonstrate the application of the proposed method.Quantitative measures and dynamic simulation show the ability to provide the satisfactory flexibility and controllability of the obtained HEN.
基金financial support from Jiangsu Collaborative Innovation Center for Cultural Creativity (XYN1911)the National Natural Science Foundation of China (22008023+1 种基金21776035)Natural Science Foundation of Jiangsu Education Department (20KJB510041)
文摘Because of its paramount importance in the successful industrial control strategy of a given heat exchanger network(HEN),the control structure designs for providing appropriate manipulated variable(MV)and controlled variable pairings have received considerable attention.However,quite frequently HENs with such control structures face the problem of hard constraints,typically holding the HENs at less controlled operating space.So both the MV pairings and the above control pairings should be considered to design a control structure.This paper investigates the systematic incorporation of the two pairings,and presents a methodology for designing such two-tier control structure.This is developed based on the sequential strategy,coupling an indirect-tier with direct-tier control structure design,wherein the intention is realized in the former stage and the latter is implemented for further optimization.The MV identification and pairing are achieved through variations in heat load of heat exchangers to design the indirect-tier control structure.Then the direct-tier control structure is followed the relative gain array pairing rules.With the proposed methodology,on the one hand,it generates an explicit connection between the MV pairings and the HEN configuration,and the quantitative interaction measure is improved to avoid the multiple solutions to break the relationship among all the control pairings into individuals;on the other hand,a two-tier control structure reveals control potentials and control system design requirements,this may avoid complex and economically unfavourable control and HEN structures.The application of proposed framework is illustrated with two cases involving the dynamic simulation analysis,the quantitative assessment and the random test.
基金financial support provided by the National Natural Science Foundation of China(22378045,22178045).
文摘The traditional methods for synthesizing flexible heat exchanger networks(HENs)are not directly applicable to inter-plant HEN challenges,primarily due to the spread of system uncertainty across plants via intermedium fluid circles.This complicates the synthesis process significantly.To tackle this issue,this study proposes a decomposed stepwise methodology to facilitate the flexible synthesis of the interplant HENs performing indirect heat integration.A decomposition strategy is proposed to divide the overall network into manageable sub-networks by dissecting the intermedium fluid circles.To address the variability in intermedium fluid temperatures,a temperature fluctuation analysis approach is developed and a heuristic rule is introduced to maintain the temperature feasibility of the intermedium fluids.To ensure adequate flexibility and cost-effectiveness of the designed networks,flexibility analysis and network retrofit steps are conducted through model-based optimization techniques.The efficacy of the method is demonstrated through two case studies,showing its potential in achieving the desired operational flexibility for inter-plant HENs.
基金supported by the financial support provided by the National Natural Science Foundation of China(Grant Nos.22008023,and 22178045)Fundamental Research Funds for the Central Universities(Grant No.DUT21RC(3)109).
文摘Solid oxide fuel cell(SOFC)is an extremely promising technology for sustainable energy conversion and storage through highly efficient electrochemical reaction at high-temperature conditions.The existing studies commonly address the final equilibrium state of the SOFC electrode reactions,giving less consideration to the micro kinetic of electrode reactions.In this paper,a kinetic model-based SOFC combined cycle power generation system is suggested to recover multiple waste heat,which includes a Kalina cycle(KC)as the bottom cycle and a Rankine cycle(RC)as the top cycle.In devneloping the proposed system,a novel kinetic model is presented for SOFC based on the microscopic mechanism of the oxygen reduction.A dynamic stochastic programming model is established to optimize the integrated system sequentially and simultaneously,with maximum power generation taken as the objective,depending on whether the SOFC system and the KC-RC system are simultaneously optimized.In sequential optimization,the output power of SOFC-KC-RC system is 320.56 kW and it is 415.04 kW using simultaneous optimization,achieving a 29.5%increase in power generation.Further comparison with the previous reports obtained by a thermodynamic model,this work leads to a 10.8%increase in power generation,showing the promising power production performance of the developed system.
