A combined-cycle power plant (CCPP) is broadly utilized in many countries to cover energy demand due to its higher efficiency than other conventional power plants. The performance of a CCPP is highly sensitive to ambi...A combined-cycle power plant (CCPP) is broadly utilized in many countries to cover energy demand due to its higher efficiency than other conventional power plants. The performance of a CCPP is highly sensitive to ambient air temperature (AAT) and the generated power varies widely during the year with temperature fluctuations. To have an accurate estimation of power generation, it is necessary to develop a model to predict the average monthly power of a CCPP considering ambient temperature changes. In the present work, the Monte Carlo (MC) method was used to obtain the average generated power of a CCPP. The case study was a combined-cycle power plant in Tehran, Iran. The region’s existing meteorological data shows significant fluctuations in the annual ambient temperature, which severely impact the performance of the mentioned plant, causing a stochastic behavior of the output power. To cope with this stochastic nature, the probability distribution of monthly outdoor temperature for 2020 was determined using the maximum likelihood estimation (MLE) method to specify the range of feasible inputs. Furthermore, the plant was accurately simulated in THERMOFLEX to capture the generated power at different temperatures. The MC method was used to couple the ambient temperature fluctuations to the output power of the plant, modeled by THERMOFLEX. Finally, the mean value of net power for each month and the average output power of the system were obtained. The results indicated that each unit of the system generates 436.3 MW in full load operation. The average deviation of the modeling results from the actual data provided by the power plant was an estimated 3.02%. Thus, it can be concluded that this method helps achieve an estimation of the monthly and annual power of a combined-cycle power plant, which are effective indexes in the economic analysis of the system.展开更多
This letter proposes a novel hybrid component and configuration model for combined-cycle gas turbines(CCGTs) participating in independent system operator(ISO) markets. The proposed model overcomes the inaccuracy issue...This letter proposes a novel hybrid component and configuration model for combined-cycle gas turbines(CCGTs) participating in independent system operator(ISO) markets. The proposed model overcomes the inaccuracy issues in the current configuration-based model while retaining its simple and flexible bidding framework of configuration-based models. The physical limitations—such as minimum online/offline time and ramping rates—are modeled for each component separately, and the cost is calculated with the bidding curves from the configuration modes. This hybrid mode can represent the current dominant bidding model in the unit commitment problem of ISOs while treating the individual components in CCGTs accurately. The commitment status of the individual components is mapped to the unique configuration mode of the CCGTs. The transitions from one configuration mode to another are also modeled. No additional binary variables are added, and numerical case studies demonstrate the effectiveness of this model for CCGT units in the unit commitment problem.展开更多
Process safety in chemical industries is considered to be one of the important goals towards sustainable development.This is due to the fact that,major accidents still occur and continue to exert significant reputatio...Process safety in chemical industries is considered to be one of the important goals towards sustainable development.This is due to the fact that,major accidents still occur and continue to exert significant reputational and financial impacts on process industries.Alarm systems constitute an indispensable component of automation as they draw the attention of process operators to any abnormal conditi on in the plant.Therefore,if deployed properly,alarm systems can play a critical role in helping plant operators ensure process safety and profitability.How-ever,in practice,many process plants suffer from poor alarm system configuration which leads to nuisance alarms and alarm floods that compromise safety.A vast amount of research has primarily focused on developing sophisticated alarm management algorithms to address specific issues.In this article,we provide a simple,practical,systematic approach that can be applied by plant engineers(i.e.,non-experts)to improve industrial alarm system performance.The proposed approach is demonstrated using an industrial power plant case study.展开更多
Flame temperature and spectral emissivity were the important parameters characterizing the sufficient degree of fuel combustion and the particle radiative characteristics in the Rocket Based Combined Cycle(RBCC)combus...Flame temperature and spectral emissivity were the important parameters characterizing the sufficient degree of fuel combustion and the particle radiative characteristics in the Rocket Based Combined Cycle(RBCC)combustor.To investigate the combustion characteristics of the complex supersonic flame in the RBCC combustor,a new radiation thermometry combined with Levenberg-Marquardt(LM)algorithm and the least squares method was proposed to measure the temperature,emissivity and spectral radiative properties based on the flame emission spectrum.In-situ measurements of the flame temperature,emissivity and spectral radiative properties were carried out in the RBCC direct-connected test bench with laser-induced plasma combustion enhancement(LIPCE)and without LIPCE.The flame average temperatures at fuel global equivalence ratio(a)of 1.0b and 0.6 with LIPCE were 4.51%and 2.08%higher than those without LIPCE.The flame combustion oscillation of kerosene tended to be stable in the recirculation zone of cavity with the thermal and chemical effects of laser induced plasma.The differences of flame temperature at a=1.0b and 0.6 were 503 K and 523 K with LIPCE,which were 20.07%and42.64%lower than those without LIPCE.The flame emissivity with methane assisted ignition was 80.46%lower than that without methane assisted ignition,due to the carbon-hydrogen ratio of kerosene was higher than that of methane.The spectral emissivities at 600 nm with LIPCE were 1.25%,22.2%,and 4.22%lower than those without LIPCE at a=1.0a(with methane assisted ignition),1.0b(without methane assisted ignition)and 0.6.The effect of concentration in the emissivity was removed by normalization to analyze the flame radiative properties in the RBCC combustor chamber.The maximum differences of flame normalized emissivity were 50.91%without LIPCE and 27.53%with LIPCE.The flame radiative properties were stabilized under the thermal and chemical effects of laser induced plasma at a=0.6.展开更多
Combined-cycle pulse detonation engines are promising contenders for hypersonic propulsion systems.In the present study,design and propulsive performance analysis of combined-cycle pulse detonation turbofan engines(PD...Combined-cycle pulse detonation engines are promising contenders for hypersonic propulsion systems.In the present study,design and propulsive performance analysis of combined-cycle pulse detonation turbofan engines(PDTEs)is presented.Analysis is done with respect to Mach number at two consecutive modes of operation:(1)Combined-cycle PDTE using a pulse detonation afterburner mode(PDA-mode)and(2)combined-cycle PDTE in pulse detonation ramjet engine mode(PDRE-mode).The performance of combined-cycle PDTEs is compared with baseline afterbuming turbofan and ramjet engines.The comparison of afterburning modes is done for Mach numbers from 0 to 3 at 15.24 km altitude conditions,while that of pulse detonation ramjet engine(PDRE)is done for Mach 1.5 to Mach 6 at 18.3 km altitude conditions.The analysis shows that the propulsive performance of a tubine engine can be greatly improved by replacing the conventional afterbumer with a pulse detonation afterburner(PDA).The PDRE also outperforms its ramjet counterpart at all flight conditions considered herein.The gains obtained are outstanding for both the combined-cycle PDTE modes compared to baseline turbofan and ramjet engines.展开更多
文摘A combined-cycle power plant (CCPP) is broadly utilized in many countries to cover energy demand due to its higher efficiency than other conventional power plants. The performance of a CCPP is highly sensitive to ambient air temperature (AAT) and the generated power varies widely during the year with temperature fluctuations. To have an accurate estimation of power generation, it is necessary to develop a model to predict the average monthly power of a CCPP considering ambient temperature changes. In the present work, the Monte Carlo (MC) method was used to obtain the average generated power of a CCPP. The case study was a combined-cycle power plant in Tehran, Iran. The region’s existing meteorological data shows significant fluctuations in the annual ambient temperature, which severely impact the performance of the mentioned plant, causing a stochastic behavior of the output power. To cope with this stochastic nature, the probability distribution of monthly outdoor temperature for 2020 was determined using the maximum likelihood estimation (MLE) method to specify the range of feasible inputs. Furthermore, the plant was accurately simulated in THERMOFLEX to capture the generated power at different temperatures. The MC method was used to couple the ambient temperature fluctuations to the output power of the plant, modeled by THERMOFLEX. Finally, the mean value of net power for each month and the average output power of the system were obtained. The results indicated that each unit of the system generates 436.3 MW in full load operation. The average deviation of the modeling results from the actual data provided by the power plant was an estimated 3.02%. Thus, it can be concluded that this method helps achieve an estimation of the monthly and annual power of a combined-cycle power plant, which are effective indexes in the economic analysis of the system.
基金supported by the U.S.Department of Energy under Contract No.DE-AC36-08GO28308 with Alliance for Sustainable Energy,LLC,the Manager and Operator of the National Renewable Energy LaboratoryU.S.Department of Energy Office of Energy Efficiency and Renewable Energy Wind Energy Technologies Office
文摘This letter proposes a novel hybrid component and configuration model for combined-cycle gas turbines(CCGTs) participating in independent system operator(ISO) markets. The proposed model overcomes the inaccuracy issues in the current configuration-based model while retaining its simple and flexible bidding framework of configuration-based models. The physical limitations—such as minimum online/offline time and ramping rates—are modeled for each component separately, and the cost is calculated with the bidding curves from the configuration modes. This hybrid mode can represent the current dominant bidding model in the unit commitment problem of ISOs while treating the individual components in CCGTs accurately. The commitment status of the individual components is mapped to the unique configuration mode of the CCGTs. The transitions from one configuration mode to another are also modeled. No additional binary variables are added, and numerical case studies demonstrate the effectiveness of this model for CCGT units in the unit commitment problem.
文摘Process safety in chemical industries is considered to be one of the important goals towards sustainable development.This is due to the fact that,major accidents still occur and continue to exert significant reputational and financial impacts on process industries.Alarm systems constitute an indispensable component of automation as they draw the attention of process operators to any abnormal conditi on in the plant.Therefore,if deployed properly,alarm systems can play a critical role in helping plant operators ensure process safety and profitability.How-ever,in practice,many process plants suffer from poor alarm system configuration which leads to nuisance alarms and alarm floods that compromise safety.A vast amount of research has primarily focused on developing sophisticated alarm management algorithms to address specific issues.In this article,we provide a simple,practical,systematic approach that can be applied by plant engineers(i.e.,non-experts)to improve industrial alarm system performance.The proposed approach is demonstrated using an industrial power plant case study.
基金supported by the National Natural Science Foundation of China (Grant Nos.52276185,52276189 and 51976057)the Fundamental Research Funds for the Central Universities (Grant No.2021MS126)+1 种基金the Natural Science Foundation of Jiangsu Province (Grant No.BK20231209)the Proof-of-Concept Project of Zhongguancun Open Laboratory (Grant No.20220981113)。
文摘Flame temperature and spectral emissivity were the important parameters characterizing the sufficient degree of fuel combustion and the particle radiative characteristics in the Rocket Based Combined Cycle(RBCC)combustor.To investigate the combustion characteristics of the complex supersonic flame in the RBCC combustor,a new radiation thermometry combined with Levenberg-Marquardt(LM)algorithm and the least squares method was proposed to measure the temperature,emissivity and spectral radiative properties based on the flame emission spectrum.In-situ measurements of the flame temperature,emissivity and spectral radiative properties were carried out in the RBCC direct-connected test bench with laser-induced plasma combustion enhancement(LIPCE)and without LIPCE.The flame average temperatures at fuel global equivalence ratio(a)of 1.0b and 0.6 with LIPCE were 4.51%and 2.08%higher than those without LIPCE.The flame combustion oscillation of kerosene tended to be stable in the recirculation zone of cavity with the thermal and chemical effects of laser induced plasma.The differences of flame temperature at a=1.0b and 0.6 were 503 K and 523 K with LIPCE,which were 20.07%and42.64%lower than those without LIPCE.The flame emissivity with methane assisted ignition was 80.46%lower than that without methane assisted ignition,due to the carbon-hydrogen ratio of kerosene was higher than that of methane.The spectral emissivities at 600 nm with LIPCE were 1.25%,22.2%,and 4.22%lower than those without LIPCE at a=1.0a(with methane assisted ignition),1.0b(without methane assisted ignition)and 0.6.The effect of concentration in the emissivity was removed by normalization to analyze the flame radiative properties in the RBCC combustor chamber.The maximum differences of flame normalized emissivity were 50.91%without LIPCE and 27.53%with LIPCE.The flame radiative properties were stabilized under the thermal and chemical effects of laser induced plasma at a=0.6.
基金This work was supported by the National Natural Science Foundation of China(NSFC No.50776045,51076064)China Scholarship Council's International Students Scholarship(CSC No.2011YXS867)from the Minister of Education,China and NUAA.
文摘Combined-cycle pulse detonation engines are promising contenders for hypersonic propulsion systems.In the present study,design and propulsive performance analysis of combined-cycle pulse detonation turbofan engines(PDTEs)is presented.Analysis is done with respect to Mach number at two consecutive modes of operation:(1)Combined-cycle PDTE using a pulse detonation afterburner mode(PDA-mode)and(2)combined-cycle PDTE in pulse detonation ramjet engine mode(PDRE-mode).The performance of combined-cycle PDTEs is compared with baseline afterbuming turbofan and ramjet engines.The comparison of afterburning modes is done for Mach numbers from 0 to 3 at 15.24 km altitude conditions,while that of pulse detonation ramjet engine(PDRE)is done for Mach 1.5 to Mach 6 at 18.3 km altitude conditions.The analysis shows that the propulsive performance of a tubine engine can be greatly improved by replacing the conventional afterbumer with a pulse detonation afterburner(PDA).The PDRE also outperforms its ramjet counterpart at all flight conditions considered herein.The gains obtained are outstanding for both the combined-cycle PDTE modes compared to baseline turbofan and ramjet engines.
