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Energy and exergy analysis of syngas production from different biomasses through air-steam gasification

S. Rupesh,C. Muraleedharan,P. Arun

《能源前沿(英文)》 2020年 第14卷 第3期   页码 607-619 doi: 10.1007/s11708-016-0439-1

摘要: Gasification is a thermo-chemical reaction which converts biomass into fuel gases in a reactor. The efficiency of conversion depends on the effective working of the gasifier. The first step in the conversion process is the selection of a suitable feedstock capable of generating more gaseous fuels. This paper analyses the performance of different biomasses during gasification through energy and exergy analysis. A quasi-equilibrium model is developed to simulate and compare the feasibility of different biomass materials as gasifier feedstock. Parametric studies are conducted to analyze the effect of temperature, steam to biomass ratio and equivalence ratio on energy and exergy efficiencies. Of the biomasses considered, sawdust has the highest energy and exergy efficiencies and lowest irreversibility. At a gasification temperature of 1000 K, the steam to biomass ratio of unity and the equivalence ratio of 0.25, the energy efficiency, exergy efficiency and irreversibility of sawdust are 35.62%, 36.98% and 10.62 MJ/kg, respectively. It is also inferred that the biomass with lower ash content and higher carbon content contributes to maximum energy and exergy efficiencies.

关键词: gasification     modeling     energy     exergy     syngas    

Exergy and exergoeconomic analyses for integration of aromatics separation with aromatics upgrading

《化学科学与工程前沿(英文)》 2023年 第17卷 第2期   页码 183-193 doi: 10.1007/s11705-022-2192-9

摘要: Methanol to aromatics produces multiple products, resulting in a limited selectivity of xylene. Aromatics upgrading is an effective way to produce more valuable xylene product, and different feed ratios generate discrepant product distributions. This work integrates the aromatics separation with toluene disproportionation, transalkylation of toluene and trimethylbenzene, and isomerization of xylene and trimethylbenzene. Exergy and exergoeconomic analyses are conducted to give insights in the splitting ratios of benzene, toluene and heavy aromatics for aromatics upgrading. First, a detailed simulation model is developed in Aspen HYSYS. Then, 300 splitting ratio sets of benzene and toluene for conversion are studied to investigate the process performances. The results indicate that there are different preferences for the splitting ratios of benzene and toluene in terms of exergy and exergoeconomic performances. The process generates lower total exergy destruction when the splitting ratio of toluene varies between 0.07 and 0.18, and that of benzene fluctuates between 0.55 and 0.6. Nevertheless, the process presents lower total product unit cost with the splitting ratio of toluene less than 0.18 and that of benzene fluctuating between 0.44 and 0.89. Besides, it is found that distillation is the biggest contributor to the total exergy destruction, accounting for 94.97%.

关键词: aromatics separation and upgrading     variant splitting ratios     total exergy destruction     total product unit cost    

Exergy analysis of multi-stage crude distillation units

Xingang LI, Canwei LIN, Lei WANG, Hong LI

《化学科学与工程前沿(英文)》 2013年 第7卷 第4期   页码 437-446 doi: 10.1007/s11705-013-1349-y

摘要: This paper aims to investigate the multi-stage effect on crude distillation units (CDUs) in thermodynamics. In this regard, we proposed three-, four-, five-, and six-stage CDU processes with all variables constrained to be almost the same except for the number of stages. We also analyzed the energy and exergy to assess the energy consumed by each process. Because additional distillation units would share the processing load and thus prevent products with low boiling points from overheating, the heat demand of the CDUs decreases with increasing stages and thus reduces the heat supply. Exergy loss is considered as a key parameter to assess these processes. When the exergy losses in heat exchangers are disregarded, the three- and four-stage CDUs have lower exergy losses than the five- and six-stage CDUs. When the overall exergy losses are considered, the optimum number of stages of CDUs depends on the exergy efficiency of heat integration.

关键词: exergy     exergy loss     crude oil distillation     multi-stage     energy saving    

A review on membrane distillation in process engineering: design and exergy equations, materials and

《化学科学与工程前沿(英文)》 2022年 第16卷 第5期   页码 592-613 doi: 10.1007/s11705-021-2105-3

摘要: One of the problems that most afflicts humanity is the lack of clean water. Water stress, which is the pressure on the quantity and quality of water resources, exists in many places throughout the World. Desalination represents a valid solution to the scarcity of fresh water and several technologies are already well applied and successful (such as reverse osmosis), producing about 100 million m3·d−1 of fresh water. Further advances in the field of desalination can be provided by innovative processes such as membrane distillation. The latter is of particular interest for the treatment of waste currents from conventional desalination processes (for example the retentate of reverse osmosis) as it allows to desalt highly concentrated currents as it is not limited by concentration polarization phenomena. New perspectives have enhanced research activities and allowed a deeper understanding of mass and heat transport phenomena, membrane wetting, polarization phenomena and have encouraged the use of materials particularly suitable for membrane distillation applications. This work summarizes recent developments in the field of membrane distillation, studies for module length optimization, commercial membrane modules developed, recent patents and advancement of membrane material.

关键词: membrane distillation     recent developments     heat and mass transfer     wetting     membrane material    

Exergy analysis and performance enhancement of isopropanol-acetone-hydrogen chemical heat pump

Min XU, Jun CAI, Xiulan HUAI

《能源前沿(英文)》 2017年 第11卷 第4期   页码 510-515 doi: 10.1007/s11708-017-0508-0

摘要: Exergy loss analysis was conducted to identify the irreversibility in each component of the isopropanol-acetone-hydrogen chemical heat pump (IAH-CHP). The results indicate that the highest irreversibility on a system basis occurs in the distillation column. Moreover, the effect of operating parameters on thermodynamic performances of the IAH-CHP was studied and the optimal conditions were obtained. Finally, the potential methods to reduce the irreversibility of the IAH-CHP system were investigated. It is found that reactive distillation is apromising alternative. The enthalpy and exergy efficiency of the IAH-CHP with reactive distillation increases by 24.1% and 23.2%, respectively.

关键词: waste heat reuse     chemical heat pump     exergy analysis     isopropanol    

Entropy flow, entropy generation, exergy flux, and optimal absorbing temperature in radiative transfer

Zeshao CHEN, Songping MO, Peng HU, Shouli JIANG, Gang WANG, Xiaofang CHENG,

《能源前沿(英文)》 2010年 第4卷 第3期   页码 301-305 doi: 10.1007/s11708-010-0006-0

摘要: Taking nonequilibrium radiative heat transfer between two surfaces as an example, the nonequilibrium thermodynamics of radiation is studied and discussed. The formulas of entropy flow, entropy generation, exergy flux, and optimal temperature of absorbing surface for maximum exergy output are derived. The result is a contribution to the thermodynamic analysis and optimization of solar energy utilization and can be applied in more complex radiative heat transfer cases.

关键词: radiative heat transfer     entropy generation     exergy     thermodynamics    

Search for a natural scientific measure of economy

John E COULTER

《环境科学与工程前沿(英文)》 2011年 第5卷 第1期   页码 111-118 doi: 10.1007/s11783-011-0285-7

摘要: Through human history, wealth has been measured in grain, gold, and, now, dollars. Though counterfeiting of coins and notes goes back a long way, it is only with electronic financial accounting in a global economy tainted by toxic loans and imaginary funds that there is an urgency to search for a realistic objective way to monitor and regulate what we are doing to our Earth and ourselves. Various schemes using analysis of utility functions, oil equivalents, entropy, energy, and other units have been tried and, while helping to understand some basic processes and flows, have always been swamped by the machinations of financiers and the attention big sums of money attract. Now, the concept of exergy, pioneered in Eastern Europe in the 1950s, is being researched, developed, and applied, especially in China, driven by the desperation to measure the reality beyond the twin specters of global financial and environmental crises. A rough inventory of the matter in the biosphere at the coordinate details of an angstrom and an appreciation of how humans harness and manipulate electromagnetic forces can be enlightening as to what is and is not sustainable. Without that understanding, any financial estimate and proposed stimulus packages or IMF reform will be wildly wrong and may even be headed in the wrong direction.

关键词: climate change     financial crisis     energy     exergy     environment    

Performance analysis of combined cycle power plant

Nikhil DEV,Rajesh ATTRI

《能源前沿(英文)》 2015年 第9卷 第4期   页码 371-386 doi: 10.1007/s11708-015-0371-9

摘要: Combined cycle power plants (CCPPs) are in operation with diverse thermodynamic cycle configurations. Assortment of thermodynamic cycle for scrupulous locality is dependent on the type of fuel available and different utilities obtained from the plant. In the present paper, seven of the practically applicable configurations of CCPP are taken into consideration. Exergetic and energetic analysis of each component of the seven configurations is conducted with the help of computer programming tool, i.e., engineering equation solver (EES) at different pressure ratios. For Case 7, the effects of pressure ratio, turbine inlet temperature and ambient relative humidity on the first and second law is studied. The thermodynamics analysis indicates that the exergy destruction in various components of the combined cycle is significantly affected by the overall pressure ratio, turbine inlet temperature and pressure loss in air filter and less affected by the ambient relative humidity.

关键词: first-law     second-law     exergy destruction     components    

Exergy-energy analysis of full repowering of a steam power plant

S. NIKBAKHT NASERABAD,K. MOBINI,A. MEHRPANAHI,M. R. ALIGOODARZ

《能源前沿(英文)》 2015年 第9卷 第1期   页码 54-67 doi: 10.1007/s11708-014-0342-6

摘要: A 320 MW old steam power plant has been chosen for repowering in this paper. Considering the technical conditions and working life of the power plant, the full repowering method has been selected from different repowering methods. The power plant repowering has been analyzed for three different feed water flow rates: a flow rate equal to the flow rate at the condenser exit in the original plant when it works at nominal load, a flow rate at maximum load, and a flow rate when all the extractions are blocked. For each flow rates, two types of gas turbines have been examined: V94.2 and V94.3A. The effect of a duct burner has then been investigated in each of the above six cases. Steam is produced by a double-pressure heat recovery steam generator (HRSG) with reheat which obtains its required heat from the exhaust gases coming from the gas turbines. The results obtained from modeling and analyzing the energy-exergy of the original steam power plant and the repowered power plant indicate that the maximum efficiency of the repowered power plant is 52.04%. This maximum efficiency occurs when utilizing two V94.3A gas turbines without duct burner in the steam flow rate of the nominal load.

关键词: full repowering     exergy analysis     V94.2 and V94.3A gas turbines     double-pressure HRSG     duct burner     Bandarabbas steam power plant     efficiency    

Exergy analysis of R1234ze(Z) as high temperature heat pump working fluid with multi-stage compression

Bin HU, Di WU, L.W. WANG, R.Z. WANG

《能源前沿(英文)》 2017年 第11卷 第4期   页码 493-502 doi: 10.1007/s11708-017-0510-6

摘要: In this paper, the simulation approach and exergy analysis of multi-stage compression high temperature heat pump (HTHP) systems with R1234ze(Z) working fluid are conducted. Both the single-stage and multi-stage compression cycles are analyzed to compare the system performance with 120°C pressurized hot water supply based upon waste heat recovery. The exergy destruction ratios of each component for different stage compression systems are compared. The results show that the exergy loss ratios of the compressor are bigger than that of the evaporator and the condenser for the single-stage compression system. The multi-stage compression system has better energy and exergy efficiencies with the increase of compression stage number. Compared with the single-stage compression system, the coefficient of performance (COP) improvements of the two-stage and three-stage compression system are 9.1% and 14.6%, respectively. When the waste heat source temperature is 60°C, the exergy efficiencies increase about 6.9% and 11.8% for the two-stage and three-stage compression system respectively.

关键词: multi-stage compression     high temperature heat pump     heat recovery     exergy destruction     R1234ze(Z) working fluid    

End-use energy utilization efficiency of Nigerian residential sector

Fidelis I. ABAM,Olayinka S. OHUNAKIN,Bethrand N. NWANKWOJIKE,Ekwe B. EKWE

《能源前沿(英文)》 2014年 第8卷 第3期   页码 322-334 doi: 10.1007/s11708-014-0329-3

摘要: In this paper, the end-use efficiencies of the different energy carriers and the overall energy efficiency in the Nigerian residential sector (NRS) were estimated using energy and exergy analysis. The energy and exergy flows were considered from 2006 to 2011. The overall energy efficiency ranges from 19.15% in 2006 to 20.19% in 2011 with a mean of (19.96±0.23)% while the overall exergy efficiency ranges from 4.34% in 2006 to 4.40% in 2011 with a mean of (4.31±0.059)%. The energy and exergy efficiency margin was 15.58% with a marginal improvement of 0.07% and 0.02%, respectively when compared with previous results. The contribution of the energy carriers to the total energy and exergy inputs were 1.45% and 1.43% for electricity, 1.95% and 3% for fossil fuel and 96.6% and 95.57% for bio-fuel. The result shows that approximately 65% of the residence use wood and biomass for domestic cooking and heating, and only a fraction of the residence have access to electricity. LPG was found to be the most efficient while kerosene, charcoal, wood and other biomass the least in this order. Electricity utilization exergy efficiency is affected by vapor-compression air conditioning application apart from low potential energy applications. In addition, this paper has suggested alternatives in the end-use application and has demonstrated the relevance of exergy analysis in enhancing sustainable energy policies and management and improved integration techniques.

关键词: end-use     energy     exergy efficiency     residential sector     Nigeria    

Exergy analysis and simulation of a 30MW cogeneration cycle

Nikhil Dev, Samsher, S. S. Kachhwaha, Rajesh Attri

《机械工程前沿(英文)》 2013年 第8卷 第2期   页码 169-180 doi: 10.1007/s11465-013-0263-9

摘要:

Cogeneration cycle is an efficient mean to recover the waste heat from the flue gases coming out of gas turbine. With the help of computer simulation, design parameters may be selected for the best performance of cogeneration cycle. In the present work a program is executed in software EES on the basis of mathematical modelling described in paper to study cogeneration cycle performance for different parameters. Results obtained are compared with the results available in literature and are found in good agreement with them. Real gas and water properties are inbuilt in the software. Results show that enthalpy of air entering the combustion chamber is higher than that of the flue gases at combustion chamber outlet. For different operative conditions, energy and exergy efficiencies follow similar trends; although, exergy efficiency values are always lower than the corresponding energy efficiency ones. From the results it is found that turbine outlet temperature (TIT) of 524°C is uniquely suited to efficient cogeneration cycle because it enables the transfer of heat from exhaust gas to the steam cycle to take place over a minimal temperature difference. This temperature range results in the maximum thermodynamic availability while operating with highest temperature and highest efficiency cogeneration cycle. Effect of cycle pressure ratio (CR), inlet air temperature (IAT) and water pressure at heat recovery steam generator (HRSG) inlet on the 30 MW cogeneration cycle is also studied.

关键词: Cogeneration cycle     air compressor     HRSG     gas turbine     regenerator     CR     IAT    

Exergy losses in premixed flames of dimethyl ether and hydrogen blends

Tongbin ZHAO, Jiabo ZHANG, Dehao JU, Zhen HUANG, Dong HAN

《能源前沿(英文)》 2019年 第13卷 第4期   页码 658-666 doi: 10.1007/s11708-019-0645-8

摘要: A second-law thermodynamic analysis was conducted for stoichiometric premixed dimethyl ether (DME)/hydrogen (H )/air flames at atmospheric pressure. The exergy losses from the irreversibility sources, i.e., chemical reaction, heat conduction and species diffusion, and those from partial combustion products were analyzed in the flames with changed fuel blends. It is observed that, regardless of the fuel blends, chemical reaction contributes most to the exergy losses, followed by incomplete combustion, and heat conduction, while mass diffusion has the least contribution to exergy loss. The results also indicate that increased H substitution decreases the exergy losses from reactions, conduction, and diffusion, primarily because of the flame thickness reduction at elevated H substitution. The decreases in exergy losses by chemical reactions and heat conduction are higher, but the exergy loss reduction by diffusion is slight. However, the exergy losses from incomplete combustion increase with H substitution, because the fractions of the unburned fuels and combustion intermediates, e.g., H and OH radical, increase. The overall exergy losses in the DME/H flames decrease by about 5% with increased H substitution from 0% to 100%.

关键词: second law analysis     flame     dimethyl ether (DME)     hydrogen     binary fuels    

Exergetic sustainability evaluation and optimization of an irreversible Brayton cycle performance

Mohammad H. AHMADI,Mohammad-Ali AHMADI,Esmaeil ABOUKAZEMPOUR,Lavinia GROSU,Fathollah POURFAYAZ,Mokhtar BIDI

《能源前沿(英文)》 2019年 第13卷 第2期   页码 399-410 doi: 10.1007/s11708-017-0445-y

摘要: Owing to the energy demands and global warming issue, employing more effective power cycles has become a responsibility. This paper presents a thermodynamical study of an irreversible Brayton cycle with the aim of optimizing the performance of the Brayton cycle. Moreover, four different schemes in the process of multi-objective optimization were suggested, and the outcomes of each scheme are assessed separately. The power output, the concepts of entropy generation, the energy, the exergy output, and the exergy efficiencies for the irreversible Brayton cycle are considered in the analysis. In the first scheme, in order to maximize the exergy output, the ecological function and the ecological coefficient of performance, a multi-objective optimization algorithm (MOEA) is used. In the second scheme, three objective functions including the exergetic performance criteria, the ecological coefficient of performance, and the ecological function are maximized at the same time by employing MOEA. In the third scenario, in order to maximize the exergy output, the exergetic performance criteria and the ecological coefficient of performance, a MOEA is performed. In the last scheme, three objective functions containing the exergetic performance criteria, the ecological coefficient of performance, and the exergy-based ecological function are maximized at the same time by employing multi-objective optimization algorithms. All the strategies are implemented via multi-objective evolutionary algorithms based on the NSGAII method. Finally, to govern the final outcome in each scheme, three well-known decision makers were employed.

关键词: entropy generation     exergy     Brayton cycle     ecological function     irreversibility    

Simulation and experiments on a solid sorption combined cooling and power system driven by the exhaust waste heat

Peng GAO, Liwei WANG, Ruzhu WANG, Yang YU

《能源前沿(英文)》 2017年 第11卷 第4期   页码 516-526 doi: 10.1007/s11708-017-0511-5

摘要: A solid sorption combined cooling and power system driven by exhaust waste heat is proposed, which consists of a MnCl sorption bed, a CaCl sorption bed, an evaporator, a condenser, an expansion valve, and a scroll expander, and ammonia is chosen as the working fluid. First, the theoretical model of the system is established, and the partitioning calculation method is proposed for sorption beds. Next, the experimental system is established, and experimental results show that the refrigerating capacity at the refrigerating temperature of –10°C and the resorption time of 30 min is 1.95 kW, and the shaft power is 109.2 W. The system can provide approximately 60% of the power for the evaporator fan and the condenser fan. Finally, the performance of the system is compared with that of the solid sorption refrigeration system. The refrigerating capacity of two systems is almost the same at the same operational condition. Therefore, the power generation process does not influence the refrigeration process. The exergy efficiency of the two systems is 0.076 and 0.047, respectively. The feasibility of the system is determined, which proves that this system is especially suitable for the exhaust waste heat recovery.

关键词: solid sorption     exhaust waste heat     combined cooling and power system     exergy efficiency    

标题 作者 时间 类型 操作

Energy and exergy analysis of syngas production from different biomasses through air-steam gasification

S. Rupesh,C. Muraleedharan,P. Arun

期刊论文

Exergy and exergoeconomic analyses for integration of aromatics separation with aromatics upgrading

期刊论文

Exergy analysis of multi-stage crude distillation units

Xingang LI, Canwei LIN, Lei WANG, Hong LI

期刊论文

A review on membrane distillation in process engineering: design and exergy equations, materials and

期刊论文

Exergy analysis and performance enhancement of isopropanol-acetone-hydrogen chemical heat pump

Min XU, Jun CAI, Xiulan HUAI

期刊论文

Entropy flow, entropy generation, exergy flux, and optimal absorbing temperature in radiative transfer

Zeshao CHEN, Songping MO, Peng HU, Shouli JIANG, Gang WANG, Xiaofang CHENG,

期刊论文

Search for a natural scientific measure of economy

John E COULTER

期刊论文

Performance analysis of combined cycle power plant

Nikhil DEV,Rajesh ATTRI

期刊论文

Exergy-energy analysis of full repowering of a steam power plant

S. NIKBAKHT NASERABAD,K. MOBINI,A. MEHRPANAHI,M. R. ALIGOODARZ

期刊论文

Exergy analysis of R1234ze(Z) as high temperature heat pump working fluid with multi-stage compression

Bin HU, Di WU, L.W. WANG, R.Z. WANG

期刊论文

End-use energy utilization efficiency of Nigerian residential sector

Fidelis I. ABAM,Olayinka S. OHUNAKIN,Bethrand N. NWANKWOJIKE,Ekwe B. EKWE

期刊论文

Exergy analysis and simulation of a 30MW cogeneration cycle

Nikhil Dev, Samsher, S. S. Kachhwaha, Rajesh Attri

期刊论文

Exergy losses in premixed flames of dimethyl ether and hydrogen blends

Tongbin ZHAO, Jiabo ZHANG, Dehao JU, Zhen HUANG, Dong HAN

期刊论文

Exergetic sustainability evaluation and optimization of an irreversible Brayton cycle performance

Mohammad H. AHMADI,Mohammad-Ali AHMADI,Esmaeil ABOUKAZEMPOUR,Lavinia GROSU,Fathollah POURFAYAZ,Mokhtar BIDI

期刊论文

Simulation and experiments on a solid sorption combined cooling and power system driven by the exhaust waste heat

Peng GAO, Liwei WANG, Ruzhu WANG, Yang YU

期刊论文