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
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
Combined cooling and power(CCP)system driven by low-grade heat is promising for improving energy efficiency.This work proposes a CCP system that integrates a regenerative organic Rankine cycle(RORC)and an absorption c...Combined cooling and power(CCP)system driven by low-grade heat is promising for improving energy efficiency.This work proposes a CCP system that integrates a regenerative organic Rankine cycle(RORC)and an absorption chiller on both driving and cooling fluid sides.The system is modeled by using the heat current method to fully consider nonlinear heat transfer and heat-work conversion constraints and resolve its behavior accurately.The off-design system simulation is performed next,showing that the fluid inlet temperatures and flow rates of cooling water as well as RORC working fluid strongly affect system performance.The off-design operation even becomes infeasible when parameters deviate from nominal values largely due to limited heat transfer capability of components,highlighting the importance of considering heat transfer constraints via heat current method.Design optimization aiming to minimize the total thermal conductance is also conducted.RORC efficiency increases by 7.9%and decreases by 12.4%after optimization,with the hot fluid inlet temperature increase from 373.15 to 403.15 K and mass flow rate ranges from 10 to 30 kg/s,emphasizing the necessity of balancing system cost and performance.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
The performance of a patented water pumping model with steam-air power was presented, which operates automatically by direct contact cooling method. The main objective was to study feasibility of a pumping model for u...The performance of a patented water pumping model with steam-air power was presented, which operates automatically by direct contact cooling method. The main objective was to study feasibility of a pumping model for underground water. In this model, a heater installed within the heat tank represented sources of waste heat as energy input for finding appropriate conditions of the 10 L pump model. The system operation had five stages： heating, pumping, vapor flow, cooling, and water suction. The overall water heads of 3, 4.5, 6 and 7.5 m were tested. At the same time, it was found that the pump with 50% air volume is sufficient for pumping water to a desired level. In the experiment, the temperatures in the heating and pumping stages were 100-103 ℃and 80-90 ℃, respectively. The pressure in the pumping stage was 12-18 kPa, and the pressure in the suction stage was about-80 kPa, sufficient for the best performance. It could pump 170 L of water at a 2 m suction head, 120 L at a 3.5 m suction head, 100 L at a 5 m suction head, and 65 L at a 6.5 m suction head in 2 h. A mathematical model for larger pumps was also presented, which operates nearly the same as the present system. Economic analysis of the 10 L pump was also included.展开更多
To improve the heat dissipation of high-power light-emitting diodes (LEDs), a cooling system with a fan is proposed. In the experiment, the LEDs array of 18 W composed of 6 LEDs of 3 W is used and the room temperature...To improve the heat dissipation of high-power light-emitting diodes (LEDs), a cooling system with a fan is proposed. In the experiment, the LEDs array of 18 W composed of 6 LEDs of 3 W is used and the room temperature is 26oC. Results show that the temperature of the substrate of LEDs reaches 62oC without the fan, however, it reaches only 32oC when the best cooling condition appears. The temperature of the LEDs decreases by 30oC since the heat produced by LEDs is transferred rapidly by the fan. The experiment demonstrates that the cooling system with the fan has good performance.展开更多
Syngas fuel such as hydrogen and carbon monoxide generated by solar energy is a promising method to use solar energy and overcome its fluctuation effectively.This study proposes a combined cooling,heating,and power sy...Syngas fuel such as hydrogen and carbon monoxide generated by solar energy is a promising method to use solar energy and overcome its fluctuation effectively.This study proposes a combined cooling,heating,and power system using the reversible solid oxide fuel cell assisted by solar energy to produce solar fuel and then supply energy products for users during the period without solar radiation.The system runs a solar-assisted solid oxide electrolysis cell mode and a solid oxide fuel cell mode.The thermodynamic models are constructed,and the energetic and exergetic performances are analyzed.Under the design work conditions,the SOEC mode’s overall system energy and exergy efficiencies are 19.0%and 20.5%,respectively.The electrical,energy and exergy efficiencies in the SOFC mode are 51.4%,71.3%,and 45.2%,respectively.The solid oxide fuel cell accounts for 60.0%of total exergy destruction,caused by the electrochemical reactions’thermodynamic irreversibilities.The increase of operating temperature of solid oxide fuel cell from 800℃to 1050℃rises the exergy and energy efficiencies by 11.3%and 12.3%,respectively.Its pressure from 0.2 to 0.7 MPa improves electrical efficiency by 13.8%while decreasing energy and exergy efficiencies by 5.2%and 6.0%,respectively.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
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.
基金supported by National Natural Science Foundation of China(Grant No.52125604)。
文摘Combined cooling and power(CCP)system driven by low-grade heat is promising for improving energy efficiency.This work proposes a CCP system that integrates a regenerative organic Rankine cycle(RORC)and an absorption chiller on both driving and cooling fluid sides.The system is modeled by using the heat current method to fully consider nonlinear heat transfer and heat-work conversion constraints and resolve its behavior accurately.The off-design system simulation is performed next,showing that the fluid inlet temperatures and flow rates of cooling water as well as RORC working fluid strongly affect system performance.The off-design operation even becomes infeasible when parameters deviate from nominal values largely due to limited heat transfer capability of components,highlighting the importance of considering heat transfer constraints via heat current method.Design optimization aiming to minimize the total thermal conductance is also conducted.RORC efficiency increases by 7.9%and decreases by 12.4%after optimization,with the hot fluid inlet temperature increase from 373.15 to 403.15 K and mass flow rate ranges from 10 to 30 kg/s,emphasizing the necessity of balancing system cost and performance.
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the financial support provided by National Research Council of Thailand and the Energy Technology Division, School of Energy Environment and Materials, King Mongkut’s University of Technology Thonburisupported by the Higher Education Research Promotion and National Research University Project of Thailand, Office of the Higher Education Commission
文摘The performance of a patented water pumping model with steam-air power was presented, which operates automatically by direct contact cooling method. The main objective was to study feasibility of a pumping model for underground water. In this model, a heater installed within the heat tank represented sources of waste heat as energy input for finding appropriate conditions of the 10 L pump model. The system operation had five stages： heating, pumping, vapor flow, cooling, and water suction. The overall water heads of 3, 4.5, 6 and 7.5 m were tested. At the same time, it was found that the pump with 50% air volume is sufficient for pumping water to a desired level. In the experiment, the temperatures in the heating and pumping stages were 100-103 ℃and 80-90 ℃, respectively. The pressure in the pumping stage was 12-18 kPa, and the pressure in the suction stage was about-80 kPa, sufficient for the best performance. It could pump 170 L of water at a 2 m suction head, 120 L at a 3.5 m suction head, 100 L at a 5 m suction head, and 65 L at a 6.5 m suction head in 2 h. A mathematical model for larger pumps was also presented, which operates nearly the same as the present system. Economic analysis of the 10 L pump was also included.
文摘To improve the heat dissipation of high-power light-emitting diodes (LEDs), a cooling system with a fan is proposed. In the experiment, the LEDs array of 18 W composed of 6 LEDs of 3 W is used and the room temperature is 26oC. Results show that the temperature of the substrate of LEDs reaches 62oC without the fan, however, it reaches only 32oC when the best cooling condition appears. The temperature of the LEDs decreases by 30oC since the heat produced by LEDs is transferred rapidly by the fan. The experiment demonstrates that the cooling system with the fan has good performance.
基金supported by the National Natural Science Foundation of China(Grant No.51876064 and 52090064)the Bureau of Shihezi Science&Technology(Grant No.2021ZD02)。
文摘Syngas fuel such as hydrogen and carbon monoxide generated by solar energy is a promising method to use solar energy and overcome its fluctuation effectively.This study proposes a combined cooling,heating,and power system using the reversible solid oxide fuel cell assisted by solar energy to produce solar fuel and then supply energy products for users during the period without solar radiation.The system runs a solar-assisted solid oxide electrolysis cell mode and a solid oxide fuel cell mode.The thermodynamic models are constructed,and the energetic and exergetic performances are analyzed.Under the design work conditions,the SOEC mode’s overall system energy and exergy efficiencies are 19.0%and 20.5%,respectively.The electrical,energy and exergy efficiencies in the SOFC mode are 51.4%,71.3%,and 45.2%,respectively.The solid oxide fuel cell accounts for 60.0%of total exergy destruction,caused by the electrochemical reactions’thermodynamic irreversibilities.The increase of operating temperature of solid oxide fuel cell from 800℃to 1050℃rises the exergy and energy efficiencies by 11.3%and 12.3%,respectively.Its pressure from 0.2 to 0.7 MPa improves electrical efficiency by 13.8%while decreasing energy and exergy efficiencies by 5.2%and 6.0%,respectively.
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.
