The determination of source-side extracted heating parameters is of great significance to the economic operation of cogeneration systems.This paper investigated the coupling performance of a cogeneration heating and p...The determination of source-side extracted heating parameters is of great significance to the economic operation of cogeneration systems.This paper investigated the coupling performance of a cogeneration heating and power system multidimensionally based on the operating characteristics of the cogeneration units,the hydraulic and thermodynamic characteristics of the heating network,and the energy loads.Taking a steam network supported by a gas-steam combined cycle cogeneration system as the research case,the interaction effect among the source-side prime movers,the heating networks,and the terminal demand thermal parameters were investigated based on the designed values,the plant testing data,and the validated simulation.The operating maps of the gas-steam combined cycle cogeneration units were obtained using THERMOFLEX,and the minimum source-side steam parameters of the steam network were solved using an inverse solution procedure based on the hydro-thermodynamic coupling model.The cogeneration operating maps indicate that the available operating domain considerably narrows with the rise of the extraction steam pressure and flow rate.The heating network inverse solution demonstrates that the source-side steam pressure and temperature can be optimized from the originally designed 1.11 MPa and 238.8°C to 1.074 MPa and 191.15°C,respectively.Under the operating strategy with the minimum source-side heating parameters,the power peak regulation depth remarkably increases to 18.30%whereas the comprehensive thermal efficiency decreases.The operation under the minimum source-side heating steam parameters can be superior to the originally designed one in the economy at a higher price of the heating steam.At a fuel price of$0.38/kg and the power to fuel price of 0.18 kg/(kW·h),the critical price ratio of heating steam to fuel is 119.1 kg/t.The influence of the power-fuel price ratio on the economic deviation appears relatively weak.展开更多
As a potentially viable renewable energy, Enhanced Geothermal Systems(EGSs) extract heat from hot dry rock(HDR) reservoirs to produce electricity and heat, which promotes the progress towards carbon peaking and carbon...As a potentially viable renewable energy, Enhanced Geothermal Systems(EGSs) extract heat from hot dry rock(HDR) reservoirs to produce electricity and heat, which promotes the progress towards carbon peaking and carbon neutralization. The main challenge for EGSs is to reduce the investment cost. In the present study, thermo-economic investigations of EGS projects are conducted. The effects of geofluid mass flow rate, wellhead temperature and loss rate on the thermo-economic performance of the EGS organic Rankine cycle(ORC) are studied. A performance comparison between EGS-ORC and the EGS combined heating and power system(CHP) is presented. Considering the CO_(2)emission reduction benefits, the influence of carbon emission trading price on the levelized cost of energy(LCOE) is also presented. It is indicated that the geofluid mass flow rate is a critical parameter in dictating the success of a project. Under the assumed typical working conditions, the LCOE of EGS-ORC and EGS-CHP systems are 24.72 and 16.1 cents/k Wh, respectively. Compared with the EGS-ORC system, the LCOE of the EGS-CHP system is reduced by 35%. EGS-CHP systems have the potential to be economically viable in the future. With carbon emission trading prices of 12.76 USD/ton, the LCOE can be reduced by approximately 8.5%.展开更多
The increasing pace of urbanization means that cities and global organizations are looking for ways to increase energy efficiency and reduce emissions. Combined cooling, heating, and power （CCHP） systems have the po...The increasing pace of urbanization means that cities and global organizations are looking for ways to increase energy efficiency and reduce emissions. Combined cooling, heating, and power （CCHP） systems have the potential to improve the energy generation efficiency of a city or urban region by providing energy for heating, cooling, and electricity simultaneously. The purpose of this study is to estimate the water consumption for energy generation use, carbon dioxide （CO2） and NOx emissions, and economic impact of implementing CCHP systems for five generic building types within the Atlanta metropolitan region, under various operational scenarios following the building thermal （heating and cooling） demands. Operating the CCHP system to follow the hourly thermal demand reduces CO2 emissions for most building types both with and without net metering. The system can be economically beneficial for all building types depending on the price of natural gas, the implementation of net metering, and the cost structure assumed for the CCHP system. The greatest reduction in water consumption for energy production and NOx emissions occurs when there is net metering and when the system is operated to meet the maximum yearly thermal demand, although this scenario also results in an increase in greenhouse gas emissions and, in some cases, cost. CCHP systems are more economical for medium office, large office, and multifamilv residential buildings.展开更多
Iran’s removing subsidy from energy carrier in four years ago leads to spike electricity price dramatically. This abrupt change increases the interest on distributed generation (DG) because of its several benefits su...Iran’s removing subsidy from energy carrier in four years ago leads to spike electricity price dramatically. This abrupt change increases the interest on distributed generation (DG) because of its several benefits such as lower electricity generation price. In Iran among all type of DGs, because of wide natural gas network infrastructure and several incentives that government legislated to support combined cooling, heat and power (CCHP) investors, this type of technology is more prevalent in comparison with other technologies. Between existing CCHP technologies, certain economic choices are to be taken into account. For different buildings with different load curves, suitable size and operation of CCHP should be calculated to make the project more feasible. If CCHP does not well suited for a position, then the whole energy efficiency would be plunged significantly. In this paper, a model to find the optimal size and operation of CCHP and auxiliary boiler for any users is proposed by considering an integrated view of electricity and natural gas network using GAMS software. Then this method is applying for a hospital in Tehran as a real case study. Finally, by applying COMFAR III software, useful financial parameters and sensitivity analysis are calculated.展开更多
To improve the overall thermal efficiency of the organic Rankine cycle（ ORC）, a simulation study was carried out for a combined heat and power（ CHP） system, using the Redlich-Kuang-Soave（ RKS） equation of state....To improve the overall thermal efficiency of the organic Rankine cycle（ ORC）, a simulation study was carried out for a combined heat and power（ CHP） system, using the Redlich-Kuang-Soave（ RKS） equation of state. In the system,R245 fa was selected as the working fluid. A scroll expander was modeled with empirical isentropic expansion efficiency.Plate heat exchangers were selected as the evaporator and the condenser, and detailed heat transfer models were programmed for both one-phase and two-phase regions. Simulations were carried out at seven different heat source temperatures（ 80,90, 100, 110, 120, 130, 140 ℃） in combination with eight different heat sink temperatures（ 20, 25, 30, 35, 40, 45, 50,55 ℃）. Results showthat in the ORC without an internal heat exchanger（ IHE）, the optimum cycle efficiencies are in the range of 7. 0% to 7. 3% when the temperature differences between the heat source and heat sink are in the range of 70 to90 ℃. Simulations on CHP reveal that domestic hot water can be produced when the heat sink inlet temperature is higher than40 ℃, and the corresponding exergy efficiency and overall thermal efficiency are 29% to 56% and 87% to 90% higher than those in the non-CHP ORC, respectively. It is found that the IHE has little effect on the improvement of work output and efficiencies for the CHP ORC.展开更多
This paper presents the solution to the combined heat and power economic dispatch problem using a direct solution algorithm for constrained optimization problems. With the potential of Combined Heat and Power (CHP) pr...This paper presents the solution to the combined heat and power economic dispatch problem using a direct solution algorithm for constrained optimization problems. With the potential of Combined Heat and Power (CHP) production to increase the efficiency of power and heat generation simultaneously having been researched and established, the increasing penetration of CHP systems, and determination of economic dispatch of power and heat assumes higher relevance. The Combined Heat and Power Economic Dispatch (CHPED) problem is a demanding optimization problem as both constraints and objective functions can be non-linear and non-convex. This paper presents an explicit formula developed for computing the system-wide incremental costs corresponding with optimal dispatch. The circumvention of the use of iterative search schemes for this crucial step is the innovation inherent in the proposed dispatch procedure. The feasible operating region of the CHP unit three is taken into account in the proposed CHPED problem model, whereas the optimal dispatch of power/heat outputs of CHP unit is determined using the direct Lagrange multiplier solution algorithm. The proposed algorithm is applied to a test system with four units and results are provided.展开更多
Combined heat and power (CHP) plants (co-generation plants) using biomass as fuel, can be an interesting alternative to the predominant electrical heating in Canada. The biomass-fueled boiler provides heat for the ste...Combined heat and power (CHP) plants (co-generation plants) using biomass as fuel, can be an interesting alternative to the predominant electrical heating in Canada. The biomass-fueled boiler provides heat for the steam cycle which in turn generates electricity from the generator connected to the steam turbine. In addition, heat from the process is supplied to a district heating system. The heat can be extracted from the system in a number of ways, by using a back-pressure steam turbine, an extraction steam turbine or by extracting heat directly from the boiler. The objective of the paper is the design, modeling and simulation of such CHP plant. The plant should be sized for providing electric-ity and heat for the Anticosti Island community in Quebec.展开更多
This paper considers comparative assessment of combined-heat-and-power (CHP) performance of three small-scale aero-derivative industrial gas turbine cycles in the petrochemical industry. The bulk of supposedly waste e...This paper considers comparative assessment of combined-heat-and-power (CHP) performance of three small-scale aero-derivative industrial gas turbine cycles in the petrochemical industry. The bulk of supposedly waste exhaust heat associated with gas turbine operation has necessitated the need for CHP application for greater fuel efficiency. This would render gas turbine cycles environ-mentally-friendly, and more economical. However, choosing a particular engine cycle option for small-scale CHP requires information about performances of CHP engine cycle options. The investigation encompasses comparative assessment of simple cycle (SC), recuperated (RC), and intercooled-recuperated (ICR) small-scale aero-derivative industrial gas turbines combined-heat-and-power (SS-ADIGT-CHP). Small-scale ADIGT engines of 1.567 MW derived from helicopter gas turbines are herein analysed in combined-heat-and-power (CHP) application. It was found that in this category of ADIGT engines, better CHP efficiency is exhibited by RC and ICR cycles than SC engine. The CHP efficiencies of RC, ICR, and SC small-scale ADIGT-CHP cycles were found to be 71%, 60%, and 56% respectively. Also, RC engine produces the highest heat recovery steam generator (HRSG) duty. The HRSG duties were found to be 3171.3 kW for RC, 2621.6 kW for ICR, and 3063.1 kW for SC. These outcomes would actually meet the objective of aiding informed preliminary choice of small-scale ADIGT engine cycle options for CHP application.展开更多
针对燃气-蒸汽联合循环且余热锅炉不补燃的热电联产机组(combined power and heat unit,CHP),首先,基于能量守恒建立天然气流量与电力电压、电流的等值关系,进而考虑功率进行变换的物理特性,构建CHP的气电变换等效电路;考虑功率进行传...针对燃气-蒸汽联合循环且余热锅炉不补燃的热电联产机组(combined power and heat unit,CHP),首先,基于能量守恒建立天然气流量与电力电压、电流的等值关系,进而考虑功率进行变换的物理特性,构建CHP的气电变换等效电路;考虑功率进行传递、释放的物理特性,构建CHP的气热转换、烟气排放及运行热损失方程;据此,确立CHP的物理特性等值模型,并定义该模型“以热定电”和“以电定热”策略下的控制参量。其次,利用牛顿法和管网水力计算基本原理,推导电潮流和气、热能流的修正方程及其雅可比元素表达式,提出计及CHP固有特性参数随系统运行状态变化的气-电-热混合能流统一分析方法。最后,通过具有不同CHP控制策略的气-电-热混合系统,验证所提方法的有效性及可行性。展开更多
The universal mathematical model of an engine is established,and an economical zone,in which an engine mainly provides medium output load at medium speed,is presented.Based on the experimental data and the universal m...The universal mathematical model of an engine is established,and an economical zone,in which an engine mainly provides medium output load at medium speed,is presented.Based on the experimental data and the universal model of such an engine above,a mathematical model of a refitted engine is provided.The boundary of the corresponding economical zone is further demarcated,and the optimal operating curve and the operating point of the engine are analyzed.Then,the energy transforming models of the power system are established in the mode of cooling,heating and power（MCHP）,the mode of heating and power（MHP）and the mode of electricity powering（MEP）.The parameter matching of the power system is optimized according to the transmission ratios of the gear box in the power distribution system.The results show that,in the MCHP,the speed transmission ratio of the engine to the gear box（ies）and the speed transmission ratio of the motor to the gear box（ims）are defined as 2.9 and 1,respectively;in the MHP,when the demand load of the power system is less than the low critical load of the economical zone,the speed transmission ratio of the motor to the engine（ime）is equal to 1,and when the demand load of the power system exceeds the low critical load of the economical zone,ime equals 0.85;in the MEP,the optimal value of ims is defined as 2.5.展开更多
The complementary of biomass and solar energy in combined cooling,heating and power(CCHP)system provides an efficient solution to address the energy crisis and environmental pollutants.This work aims to propose a mult...The complementary of biomass and solar energy in combined cooling,heating and power(CCHP)system provides an efficient solution to address the energy crisis and environmental pollutants.This work aims to propose a multi-objective optimization model based on the life cycle assessment(LCA)method for the optimal design of hybrid solar and biomass system.The life-cycle process of the poly-generation system is divided into six phases to analyze energy consumption and greenhouse gas emissions.The comprehensive performances of the hybrid system are optimized by incorporating the evaluation criteria,including environmental impact in the whole life cycle,renewable energy contribution and economic benefit.The non-dominated sorting genetic algorithmⅡ(NSGA-Ⅱ)with the technique for order preference by similarity to ideal solution(TOPSIS)method is employed to search the Pareto frontier result and thereby achieve optimal performance.The developed optimization methodology is used for a case study in an industrial park.The results indicate that the best performance from the optimized hybrid system is reached with the environmental impact load reduction rate(EILRR)of 46.03%,renewable energy contribution proportion(RECP)of 92.73%and annual total cost saving rate(ATCSR)of35.75%,respectively.By comparing pollutant-eq emissions of different stages,the operation phase emits the largest pollutant followed by the phase of raw material acquisition.Overall,this study reveals that the proposed multi-objective optimization model integrated with LCA method delivers an alternative path for the design and optimization of more sustainable CCHP system.展开更多
Although numerous studies have considered the two traditional operation strategies:following the electric load(FEL)and following the thermal load(FTL),for combined cooling,heating,and power(CCHP)systems in different c...Although numerous studies have considered the two traditional operation strategies:following the electric load(FEL)and following the thermal load(FTL),for combined cooling,heating,and power(CCHP)systems in different case studies,there are limited theoretical studies on the quantification methods to assess the feasibility of these two strategies in different load demands scenarios.Therefore,instead of a case study,we have undertaken a theoretical analysis of the suitable application scenarios for FEL and FTL strategies based on the energy-matching performance between systems'provision and users'demands.To compare the calculation models of energy saving rate(ESR)for FEL and FTL strategies in the left and right sub-regions of the energy-supply curve,a comprehensive parameter(^)that combines three inherently influential factors(off-design operation parameter,energy-matching parameter,and install capacity coefficient)is defined to determine the optimal installed capacity and feasibility of FEL or FTL strategies quantitatively.The results indicate that greater value of x contribute to a better energy saving performance,and FEL strategy shows better performance than FTL in most load demands scenarios,and the optimal installed capacity occurs when the load demand points were located in different regions of the energy-supply curve.Finally,taking a hotel in Beijing as an example,the value of the optimal install capacity coefficient is 0.845 and the FEL strategy is also suggested,and compared to the maximum install capacity,the average values of the ESR on a typical summer day,transition season,and winter can be enhanced by 3.9%,8.8%,and 1.89%,respectively.展开更多
This article is focused on technical and economic evaluation of more than 6-years experiences of operating the Waste Heat Recovery technology—the manner and system of flue gas processing generated in the combustion p...This article is focused on technical and economic evaluation of more than 6-years experiences of operating the Waste Heat Recovery technology—the manner and system of flue gas processing generated in the combustion process in heat & power plants, cogeneration units, etc., which burn the gaseous fuel, primarily natural gas, or methane, biogas, geothermal gas, or other gaseous mixtures containing hydrogen. The solution proposes a more effective and non-traditional use of gaseous fuel for heating, the flue gases of which are processed in order to extract additional utilisable heat, with potential elimination of CO2 from them. Deploying of the heating plant in an island regime (OFF-GRID) enables definition of the benefits brought by the 3 years of operational experience and presents visions for the future offering the possibility to utilise the support energy services at the municipal as well as regional level.展开更多
Integrated energy systems(IESs)can improve energy efficiency and reduce carbon emissions,essential for achieving peak carbon emissions and carbon neutrality.This study investigated the characteristics of the CHP model...Integrated energy systems(IESs)can improve energy efficiency and reduce carbon emissions,essential for achieving peak carbon emissions and carbon neutrality.This study investigated the characteristics of the CHP model considering P2G and carbon capture systems,and a two-stage robust optimization model of the electricity-heat-gascold integrated energy system was developed.First,a CHP model considering the P2G and carbon capture system was established,and the electric-thermal coupling characteristics and P2G capacity constraints of the model were derived,which proved that the model could weaken the electric-thermal coupling characteristics,increase the electric power regulation range,and reduce carbon emissions.Subsequently,a two-stage robust optimal scheduling model of an IES was constructed,in which the objective function in the day-ahead scheduling stage was to minimize the start-up and shutdown costs.The objective function in the real-time scheduling stage was to minimize the equipment operating costs,carbon emission costs,wind curtailment,and solar curtailment costs,considering multiple uncertainties.Finally,after the objective function is linearized with a ψ-piecewise method,the model is solved based on the C&CG algorithm.Simulation results show that the proposed model can effectively absorb renewable energy and reduce the total cost of the system.展开更多
The customarily discarded exhaust from the fossil fuel-based power plants of the off-grid mines holds the thermal potential to fulfill the heating requirement of the underground operation.This present research fills i...The customarily discarded exhaust from the fossil fuel-based power plants of the off-grid mines holds the thermal potential to fulfill the heating requirement of the underground operation.This present research fills in an important research gap by investigating the coupling effect between a diesel exhaust heat recovery and an intake air heating system employed in a remote mine.An integrative approach comprising analytical,numerical,and experimental assessment has been adapted.The novel analytical model developed here establishes the reliability of the proposed mine heating system by providing comparative analysis between a coupled and a decoupled system.The effect of working fluid variation has been examined by the numerical analysis and the possible improvement has been identified.Experimental investigations present a demonstration of the successful lab-scale implementation of the concept and validate the numerical and analytical models developed.Successful deployment of the fully coupled mine heating system proposed here will assist the mining industry on its journey towards energy-efficient,and sustainable mining practices through nearly 70%reduction in fossil fuel consumption for heating intentions.展开更多
通过综合考虑冷热电联供(CCHP)系统中各类约束条件,基于夏冬两季典型日负荷需求曲线,构建了吸收式制冷机、燃气内燃机和燃气锅炉等主要机组设备模型。针对区域内系统经济性与环保性两者的协调优化问题,提出一种改进的基于分解的多目标...通过综合考虑冷热电联供(CCHP)系统中各类约束条件,基于夏冬两季典型日负荷需求曲线,构建了吸收式制冷机、燃气内燃机和燃气锅炉等主要机组设备模型。针对区域内系统经济性与环保性两者的协调优化问题,提出一种改进的基于分解的多目标进化算法(multi-objective optimization algorithm based on Decomposition, MOEA/D)对系统模型进行多目标优化求解。最后以某商业区能源站为实际算例,通过Matlab进行仿真。仿真结果显示所提出的系统优化方法,能使该能源站的运行更加经济与高效。展开更多
Combined Heat and Power Economic Dispatch(CHPED)is an important problem in the energy field,and it is beneficial for improving the utilization efficiency of power and heat energies.This paper proposes a Modified Genet...Combined Heat and Power Economic Dispatch(CHPED)is an important problem in the energy field,and it is beneficial for improving the utilization efficiency of power and heat energies.This paper proposes a Modified Genetic Algorithm(MGA)to determine the power and heat outputs of three kinds of units for CHPED.First,MGA replaces the simulated binary crossover by a new one based on the uniform and guassian distributions,and its convergence can be enhanced.Second,MGA modi-fies the mutation operator by introducing a disturbance coefficient based on guassian distribution,which can decrease the risk of being trapped into local optima.Eight instances with or without prohibited operating zones are used to investigate the efficiencies of MGA and other four genetic algorithms for CHPED.In comparison with the other algorithms,MGA has reduced generation costs by at least 562.73$,1068.7$,522.68$and 1016.24$,respectively,for instances 3,4,7 and 8,and it has reduced generation costs by at most 848.22$,3642.85$,897.63$and 3812.65$,respectively,for instances 3,4,7 and 8.Therefore,MGA has desirable convergence and stability for CHPED in comparison with the other four genetic algorithms.展开更多
基金Guangdong Province Key Laboratory of Efficient and Clean Energy Utilization(South China University of Technology)(2013A061401005)Research Fund(JMSWFW-2110-044)from Zhongshan Jiaming Electric Power Co.,Ltd.
文摘The determination of source-side extracted heating parameters is of great significance to the economic operation of cogeneration systems.This paper investigated the coupling performance of a cogeneration heating and power system multidimensionally based on the operating characteristics of the cogeneration units,the hydraulic and thermodynamic characteristics of the heating network,and the energy loads.Taking a steam network supported by a gas-steam combined cycle cogeneration system as the research case,the interaction effect among the source-side prime movers,the heating networks,and the terminal demand thermal parameters were investigated based on the designed values,the plant testing data,and the validated simulation.The operating maps of the gas-steam combined cycle cogeneration units were obtained using THERMOFLEX,and the minimum source-side steam parameters of the steam network were solved using an inverse solution procedure based on the hydro-thermodynamic coupling model.The cogeneration operating maps indicate that the available operating domain considerably narrows with the rise of the extraction steam pressure and flow rate.The heating network inverse solution demonstrates that the source-side steam pressure and temperature can be optimized from the originally designed 1.11 MPa and 238.8°C to 1.074 MPa and 191.15°C,respectively.Under the operating strategy with the minimum source-side heating parameters,the power peak regulation depth remarkably increases to 18.30%whereas the comprehensive thermal efficiency decreases.The operation under the minimum source-side heating steam parameters can be superior to the originally designed one in the economy at a higher price of the heating steam.At a fuel price of$0.38/kg and the power to fuel price of 0.18 kg/(kW·h),the critical price ratio of heating steam to fuel is 119.1 kg/t.The influence of the power-fuel price ratio on the economic deviation appears relatively weak.
基金supported by Major International(Regional)Joint Research Project of the National Natural Science Foundation of China(61320106011)National High Technology Research and Development Program of China(863 Program)(2014AA052802)National Natural Science Foundation of China(61573224)
基金financial support provided by the National Key Research and Development Program of China(No.2018YFB1501805)China Geological Survey Project(Grant No.DD2019135,and No.DD20211336)。
文摘As a potentially viable renewable energy, Enhanced Geothermal Systems(EGSs) extract heat from hot dry rock(HDR) reservoirs to produce electricity and heat, which promotes the progress towards carbon peaking and carbon neutralization. The main challenge for EGSs is to reduce the investment cost. In the present study, thermo-economic investigations of EGS projects are conducted. The effects of geofluid mass flow rate, wellhead temperature and loss rate on the thermo-economic performance of the EGS organic Rankine cycle(ORC) are studied. A performance comparison between EGS-ORC and the EGS combined heating and power system(CHP) is presented. Considering the CO_(2)emission reduction benefits, the influence of carbon emission trading price on the levelized cost of energy(LCOE) is also presented. It is indicated that the geofluid mass flow rate is a critical parameter in dictating the success of a project. Under the assumed typical working conditions, the LCOE of EGS-ORC and EGS-CHP systems are 24.72 and 16.1 cents/k Wh, respectively. Compared with the EGS-ORC system, the LCOE of the EGS-CHP system is reduced by 35%. EGS-CHP systems have the potential to be economically viable in the future. With carbon emission trading prices of 12.76 USD/ton, the LCOE can be reduced by approximately 8.5%.
基金This work was partially supported by the Brook Byers Institute for Sustainable Systems, the Hightower Chair, Georgia Research Alliance, and grants （083604, 1441208） from the US National Science Foundation Program for Emerging Frontiers in Research and Innovation （EFRI）.
文摘The increasing pace of urbanization means that cities and global organizations are looking for ways to increase energy efficiency and reduce emissions. Combined cooling, heating, and power （CCHP） systems have the potential to improve the energy generation efficiency of a city or urban region by providing energy for heating, cooling, and electricity simultaneously. The purpose of this study is to estimate the water consumption for energy generation use, carbon dioxide （CO2） and NOx emissions, and economic impact of implementing CCHP systems for five generic building types within the Atlanta metropolitan region, under various operational scenarios following the building thermal （heating and cooling） demands. Operating the CCHP system to follow the hourly thermal demand reduces CO2 emissions for most building types both with and without net metering. The system can be economically beneficial for all building types depending on the price of natural gas, the implementation of net metering, and the cost structure assumed for the CCHP system. The greatest reduction in water consumption for energy production and NOx emissions occurs when there is net metering and when the system is operated to meet the maximum yearly thermal demand, although this scenario also results in an increase in greenhouse gas emissions and, in some cases, cost. CCHP systems are more economical for medium office, large office, and multifamilv residential buildings.
文摘Iran’s removing subsidy from energy carrier in four years ago leads to spike electricity price dramatically. This abrupt change increases the interest on distributed generation (DG) because of its several benefits such as lower electricity generation price. In Iran among all type of DGs, because of wide natural gas network infrastructure and several incentives that government legislated to support combined cooling, heat and power (CCHP) investors, this type of technology is more prevalent in comparison with other technologies. Between existing CCHP technologies, certain economic choices are to be taken into account. For different buildings with different load curves, suitable size and operation of CCHP should be calculated to make the project more feasible. If CCHP does not well suited for a position, then the whole energy efficiency would be plunged significantly. In this paper, a model to find the optimal size and operation of CCHP and auxiliary boiler for any users is proposed by considering an integrated view of electricity and natural gas network using GAMS software. Then this method is applying for a hospital in Tehran as a real case study. Finally, by applying COMFAR III software, useful financial parameters and sensitivity analysis are calculated.
基金Special Fund for IndustryUniversity and Research Cooperation(No.2011DFR61130)
文摘To improve the overall thermal efficiency of the organic Rankine cycle（ ORC）, a simulation study was carried out for a combined heat and power（ CHP） system, using the Redlich-Kuang-Soave（ RKS） equation of state. In the system,R245 fa was selected as the working fluid. A scroll expander was modeled with empirical isentropic expansion efficiency.Plate heat exchangers were selected as the evaporator and the condenser, and detailed heat transfer models were programmed for both one-phase and two-phase regions. Simulations were carried out at seven different heat source temperatures（ 80,90, 100, 110, 120, 130, 140 ℃） in combination with eight different heat sink temperatures（ 20, 25, 30, 35, 40, 45, 50,55 ℃）. Results showthat in the ORC without an internal heat exchanger（ IHE）, the optimum cycle efficiencies are in the range of 7. 0% to 7. 3% when the temperature differences between the heat source and heat sink are in the range of 70 to90 ℃. Simulations on CHP reveal that domestic hot water can be produced when the heat sink inlet temperature is higher than40 ℃, and the corresponding exergy efficiency and overall thermal efficiency are 29% to 56% and 87% to 90% higher than those in the non-CHP ORC, respectively. It is found that the IHE has little effect on the improvement of work output and efficiencies for the CHP ORC.
文摘This paper presents the solution to the combined heat and power economic dispatch problem using a direct solution algorithm for constrained optimization problems. With the potential of Combined Heat and Power (CHP) production to increase the efficiency of power and heat generation simultaneously having been researched and established, the increasing penetration of CHP systems, and determination of economic dispatch of power and heat assumes higher relevance. The Combined Heat and Power Economic Dispatch (CHPED) problem is a demanding optimization problem as both constraints and objective functions can be non-linear and non-convex. This paper presents an explicit formula developed for computing the system-wide incremental costs corresponding with optimal dispatch. The circumvention of the use of iterative search schemes for this crucial step is the innovation inherent in the proposed dispatch procedure. The feasible operating region of the CHP unit three is taken into account in the proposed CHPED problem model, whereas the optimal dispatch of power/heat outputs of CHP unit is determined using the direct Lagrange multiplier solution algorithm. The proposed algorithm is applied to a test system with four units and results are provided.
文摘Combined heat and power (CHP) plants (co-generation plants) using biomass as fuel, can be an interesting alternative to the predominant electrical heating in Canada. The biomass-fueled boiler provides heat for the steam cycle which in turn generates electricity from the generator connected to the steam turbine. In addition, heat from the process is supplied to a district heating system. The heat can be extracted from the system in a number of ways, by using a back-pressure steam turbine, an extraction steam turbine or by extracting heat directly from the boiler. The objective of the paper is the design, modeling and simulation of such CHP plant. The plant should be sized for providing electric-ity and heat for the Anticosti Island community in Quebec.
文摘This paper considers comparative assessment of combined-heat-and-power (CHP) performance of three small-scale aero-derivative industrial gas turbine cycles in the petrochemical industry. The bulk of supposedly waste exhaust heat associated with gas turbine operation has necessitated the need for CHP application for greater fuel efficiency. This would render gas turbine cycles environ-mentally-friendly, and more economical. However, choosing a particular engine cycle option for small-scale CHP requires information about performances of CHP engine cycle options. The investigation encompasses comparative assessment of simple cycle (SC), recuperated (RC), and intercooled-recuperated (ICR) small-scale aero-derivative industrial gas turbines combined-heat-and-power (SS-ADIGT-CHP). Small-scale ADIGT engines of 1.567 MW derived from helicopter gas turbines are herein analysed in combined-heat-and-power (CHP) application. It was found that in this category of ADIGT engines, better CHP efficiency is exhibited by RC and ICR cycles than SC engine. The CHP efficiencies of RC, ICR, and SC small-scale ADIGT-CHP cycles were found to be 71%, 60%, and 56% respectively. Also, RC engine produces the highest heat recovery steam generator (HRSG) duty. The HRSG duties were found to be 3171.3 kW for RC, 2621.6 kW for ICR, and 3063.1 kW for SC. These outcomes would actually meet the objective of aiding informed preliminary choice of small-scale ADIGT engine cycle options for CHP application.
文摘针对燃气-蒸汽联合循环且余热锅炉不补燃的热电联产机组(combined power and heat unit,CHP),首先,基于能量守恒建立天然气流量与电力电压、电流的等值关系,进而考虑功率进行变换的物理特性,构建CHP的气电变换等效电路;考虑功率进行传递、释放的物理特性,构建CHP的气热转换、烟气排放及运行热损失方程;据此,确立CHP的物理特性等值模型,并定义该模型“以热定电”和“以电定热”策略下的控制参量。其次,利用牛顿法和管网水力计算基本原理,推导电潮流和气、热能流的修正方程及其雅可比元素表达式,提出计及CHP固有特性参数随系统运行状态变化的气-电-热混合能流统一分析方法。最后,通过具有不同CHP控制策略的气-电-热混合系统,验证所提方法的有效性及可行性。
基金The Natural Science Foundation of Jiangsu Higher Education Institutions of China(No.2009112TSJ0124)
文摘The universal mathematical model of an engine is established,and an economical zone,in which an engine mainly provides medium output load at medium speed,is presented.Based on the experimental data and the universal model of such an engine above,a mathematical model of a refitted engine is provided.The boundary of the corresponding economical zone is further demarcated,and the optimal operating curve and the operating point of the engine are analyzed.Then,the energy transforming models of the power system are established in the mode of cooling,heating and power（MCHP）,the mode of heating and power（MHP）and the mode of electricity powering（MEP）.The parameter matching of the power system is optimized according to the transmission ratios of the gear box in the power distribution system.The results show that,in the MCHP,the speed transmission ratio of the engine to the gear box（ies）and the speed transmission ratio of the motor to the gear box（ims）are defined as 2.9 and 1,respectively;in the MHP,when the demand load of the power system is less than the low critical load of the economical zone,the speed transmission ratio of the motor to the engine（ime）is equal to 1,and when the demand load of the power system exceeds the low critical load of the economical zone,ime equals 0.85;in the MEP,the optimal value of ims is defined as 2.5.
基金supported by the National Natural Science Foundation of China(Grant No.51976164)。
文摘The complementary of biomass and solar energy in combined cooling,heating and power(CCHP)system provides an efficient solution to address the energy crisis and environmental pollutants.This work aims to propose a multi-objective optimization model based on the life cycle assessment(LCA)method for the optimal design of hybrid solar and biomass system.The life-cycle process of the poly-generation system is divided into six phases to analyze energy consumption and greenhouse gas emissions.The comprehensive performances of the hybrid system are optimized by incorporating the evaluation criteria,including environmental impact in the whole life cycle,renewable energy contribution and economic benefit.The non-dominated sorting genetic algorithmⅡ(NSGA-Ⅱ)with the technique for order preference by similarity to ideal solution(TOPSIS)method is employed to search the Pareto frontier result and thereby achieve optimal performance.The developed optimization methodology is used for a case study in an industrial park.The results indicate that the best performance from the optimized hybrid system is reached with the environmental impact load reduction rate(EILRR)of 46.03%,renewable energy contribution proportion(RECP)of 92.73%and annual total cost saving rate(ATCSR)of35.75%,respectively.By comparing pollutant-eq emissions of different stages,the operation phase emits the largest pollutant followed by the phase of raw material acquisition.Overall,this study reveals that the proposed multi-objective optimization model integrated with LCA method delivers an alternative path for the design and optimization of more sustainable CCHP system.
基金This work was supported by the National K ey Research and Development Program of China(Grant No.2016 Y F B 0901405)the Science Fund for Creative Research Groups(No.51621062)the National Natural Science Foundation of China(Grant No.51806117,51236004).
文摘Although numerous studies have considered the two traditional operation strategies:following the electric load(FEL)and following the thermal load(FTL),for combined cooling,heating,and power(CCHP)systems in different case studies,there are limited theoretical studies on the quantification methods to assess the feasibility of these two strategies in different load demands scenarios.Therefore,instead of a case study,we have undertaken a theoretical analysis of the suitable application scenarios for FEL and FTL strategies based on the energy-matching performance between systems'provision and users'demands.To compare the calculation models of energy saving rate(ESR)for FEL and FTL strategies in the left and right sub-regions of the energy-supply curve,a comprehensive parameter(^)that combines three inherently influential factors(off-design operation parameter,energy-matching parameter,and install capacity coefficient)is defined to determine the optimal installed capacity and feasibility of FEL or FTL strategies quantitatively.The results indicate that greater value of x contribute to a better energy saving performance,and FEL strategy shows better performance than FTL in most load demands scenarios,and the optimal installed capacity occurs when the load demand points were located in different regions of the energy-supply curve.Finally,taking a hotel in Beijing as an example,the value of the optimal install capacity coefficient is 0.845 and the FEL strategy is also suggested,and compared to the maximum install capacity,the average values of the ESR on a typical summer day,transition season,and winter can be enhanced by 3.9%,8.8%,and 1.89%,respectively.
文摘This article is focused on technical and economic evaluation of more than 6-years experiences of operating the Waste Heat Recovery technology—the manner and system of flue gas processing generated in the combustion process in heat & power plants, cogeneration units, etc., which burn the gaseous fuel, primarily natural gas, or methane, biogas, geothermal gas, or other gaseous mixtures containing hydrogen. The solution proposes a more effective and non-traditional use of gaseous fuel for heating, the flue gases of which are processed in order to extract additional utilisable heat, with potential elimination of CO2 from them. Deploying of the heating plant in an island regime (OFF-GRID) enables definition of the benefits brought by the 3 years of operational experience and presents visions for the future offering the possibility to utilise the support energy services at the municipal as well as regional level.
基金supported by the National Natural Science Foundation of China(Grant number 51977154)。
文摘Integrated energy systems(IESs)can improve energy efficiency and reduce carbon emissions,essential for achieving peak carbon emissions and carbon neutrality.This study investigated the characteristics of the CHP model considering P2G and carbon capture systems,and a two-stage robust optimization model of the electricity-heat-gascold integrated energy system was developed.First,a CHP model considering the P2G and carbon capture system was established,and the electric-thermal coupling characteristics and P2G capacity constraints of the model were derived,which proved that the model could weaken the electric-thermal coupling characteristics,increase the electric power regulation range,and reduce carbon emissions.Subsequently,a two-stage robust optimal scheduling model of an IES was constructed,in which the objective function in the day-ahead scheduling stage was to minimize the start-up and shutdown costs.The objective function in the real-time scheduling stage was to minimize the equipment operating costs,carbon emission costs,wind curtailment,and solar curtailment costs,considering multiple uncertainties.Finally,after the objective function is linearized with a ψ-piecewise method,the model is solved based on the C&CG algorithm.Simulation results show that the proposed model can effectively absorb renewable energy and reduce the total cost of the system.
文摘The customarily discarded exhaust from the fossil fuel-based power plants of the off-grid mines holds the thermal potential to fulfill the heating requirement of the underground operation.This present research fills in an important research gap by investigating the coupling effect between a diesel exhaust heat recovery and an intake air heating system employed in a remote mine.An integrative approach comprising analytical,numerical,and experimental assessment has been adapted.The novel analytical model developed here establishes the reliability of the proposed mine heating system by providing comparative analysis between a coupled and a decoupled system.The effect of working fluid variation has been examined by the numerical analysis and the possible improvement has been identified.Experimental investigations present a demonstration of the successful lab-scale implementation of the concept and validate the numerical and analytical models developed.Successful deployment of the fully coupled mine heating system proposed here will assist the mining industry on its journey towards energy-efficient,and sustainable mining practices through nearly 70%reduction in fossil fuel consumption for heating intentions.
文摘通过综合考虑冷热电联供(CCHP)系统中各类约束条件,基于夏冬两季典型日负荷需求曲线,构建了吸收式制冷机、燃气内燃机和燃气锅炉等主要机组设备模型。针对区域内系统经济性与环保性两者的协调优化问题,提出一种改进的基于分解的多目标进化算法(multi-objective optimization algorithm based on Decomposition, MOEA/D)对系统模型进行多目标优化求解。最后以某商业区能源站为实际算例,通过Matlab进行仿真。仿真结果显示所提出的系统优化方法,能使该能源站的运行更加经济与高效。
基金supported by the National Natural Science Foundation of China(NSFC)under Grant 61873272,62073327in part by the Natural Science Foundation of Jiangsu Province under Grant BK20200086,BK20200631.
文摘Combined Heat and Power Economic Dispatch(CHPED)is an important problem in the energy field,and it is beneficial for improving the utilization efficiency of power and heat energies.This paper proposes a Modified Genetic Algorithm(MGA)to determine the power and heat outputs of three kinds of units for CHPED.First,MGA replaces the simulated binary crossover by a new one based on the uniform and guassian distributions,and its convergence can be enhanced.Second,MGA modi-fies the mutation operator by introducing a disturbance coefficient based on guassian distribution,which can decrease the risk of being trapped into local optima.Eight instances with or without prohibited operating zones are used to investigate the efficiencies of MGA and other four genetic algorithms for CHPED.In comparison with the other algorithms,MGA has reduced generation costs by at least 562.73$,1068.7$,522.68$and 1016.24$,respectively,for instances 3,4,7 and 8,and it has reduced generation costs by at most 848.22$,3642.85$,897.63$and 3812.65$,respectively,for instances 3,4,7 and 8.Therefore,MGA has desirable convergence and stability for CHPED in comparison with the other four genetic algorithms.
