Two novel thermal cycles based on Brayton cycle and Rankine cycle are proposed, respectively, which integrate the recovery of low-level waste heat and Liquefied Nature Gas （LNG） cold energy utilization for power gen...Two novel thermal cycles based on Brayton cycle and Rankine cycle are proposed, respectively, which integrate the recovery of low-level waste heat and Liquefied Nature Gas （LNG） cold energy utilization for power generation. Cascade utilization of energy is realized in the two thermal cycles, where low-level waste heat,low-temperature exergy and pressure exergy of LNG are utilized efficiently through the system synthesis. The simulations are carried out using the commercial Aspen Plus 10.2, and the results are analyzed. Compared with the conventional Brayton cycle and Rankine cycle, the two novel cycles bring 60.94% and 60% in exergy efficiency, respectively and 53.08% and 52.31% in thermal efficiency, respectively.展开更多
Modulating the macro/nanoarchitecture of evaporators to effectively harness diverse renewable energy sources is of paramount importance for optimizing the performance of solar-driven interfacial evaporation.Inspired b...Modulating the macro/nanoarchitecture of evaporators to effectively harness diverse renewable energy sources is of paramount importance for optimizing the performance of solar-driven interfacial evaporation.Inspired by the geometric structure of a windmill,we designed an innovative solar evaporator that expertly harnesses both strong and weak convection.During the purification of heavy metal wastewater,the maximum evaporation rate can reach 4.95 kg m^(−2)h^(−1)under one sun irradiation by introducing an ultralow wind flow(0.1 m s^(−1)),yielding an evaporation rate that is twice that of traditional evaporators.However,the gradual deposition of inorganic salt sediments on the evaporator surface is clearly observable.To address this issue,we present several innovative proof-of-concept cascade treatments that significantly extend the evaporator’s operational lifespan.The innovative design and exceptional performance of this solar evaporator open avenues for advancements in sustainable water treatment,energy generation,and environmental remediation.展开更多
At present,the oxy-fuel combustion(O_(2)/CO_(2)circulating combustion)is dominant in natural gas generating systems,but it consumes much energy for air separation oxygen generation and carbon capture,leading to a seve...At present,the oxy-fuel combustion(O_(2)/CO_(2)circulating combustion)is dominant in natural gas generating systems,but it consumes much energy for air separation oxygen generation and carbon capture,leading to a severe reduction of generating efficiency.The O_(2)/H_(2)O combustion system,as the new generation of an oxy-combustion system,is superior to the oxy-fuel combustion,and its pollutant emission is lower,but during its combustion,air separation oxygen generation is still needed,so CO_(2)compression energy consumption is still higher.In this paper,a set of carbon capture system applying LNG cold energy to the O_(2)/H_(2)O combustion was developed,and its mathematical model was established to calculate thermal efficiency and exergy efficiency.And then,it was compared with the COOLCEP system which also makes use of LNG cold energy for carbon capture.The combustion process of this system is operated under high pressure with H_(2)O as the circulation medium,and LNG is utilized in a cascading pattern,so the energy consumption of air separation oxygen generation and carbon capture system is reduced,the generating efficiency of the system is increased and carbon capture is conducted at low cost.The thermal efficiency and energy efficiency of this system increase continuously as the inlet temperature of gas turbine rises.When the flow rate of circulating water is 13.5 kmol/s,the combustion pressure is 1.6 MPa,and the inlet temperature of gas turbine reaches 1328.1℃,the thermal efficiency and exergy efficiency is 57.9%(maximum)and 42.7%,respectively.Compared with COOLCEP system,the O_(2)/H_(2)O combustion system is much lower in energy consumption and its thermal efficiency and exergy efficiency are 6.3%and 5.4%higher,respectively.展开更多
This paper briefly summarizes the current status of typical solar thermal power plant system,including system composition,thermal energy storage medium and performance.The thermo-physical properties of the storage med...This paper briefly summarizes the current status of typical solar thermal power plant system,including system composition,thermal energy storage medium and performance.The thermo-physical properties of the storage medium are some of the most important factors that affect overall efficiency of the system,because some renewable energy sources such as solar and wind are unpredictable.A thermal storage system is therefore necessary to store energy for continuous usage.Based on the form of storage or the mode of system connection,heat exchangers of a thermal storage system can produce different temperature ranges of heat transfer fluid to realize energy cascade utilization.Founded upon the review,a small hybrid energy system with a molten-salt energy storage system is proposed to solve the problems of heating,cooling,and electricity consumption of a 1000 m2 training hall at school.The system uses molten-salt storage tank,water tank and steam generator to change the temperature of heat transfer fluid,in order to realize thermal energy cascade utilization.Compared to the existing heating and cooling system,the proposed system needs more renewable energy and less municipal energy to achieve the same results according to simulation analysis.Furthermore,by improving the original heating and cooling system,PMV has been improved.The comprehensive efficiency of solar energy utilization has been increased to 83%.展开更多
We propose and demonstrate a simplified and tunable frequency interval optical frequency comb(OFC) generator based on a dual-drive Mach-Zehnder modulator(DD-MZM) using a single continuous-wave(CW) laser and low-power ...We propose and demonstrate a simplified and tunable frequency interval optical frequency comb(OFC) generator based on a dual-drive Mach-Zehnder modulator(DD-MZM) using a single continuous-wave(CW) laser and low-power radio frequency(RF) driven signal. A mathematical model for the scheme is established. The 21-and 29-mode OFCs with frequency interval ranging from 6 GHz to 40 GHz are obtained under DD-MZM driven by a low-power RF signal within a maximum bandwidth of 1.12 THz. The generated OFCs exhibit spectral flatnesses of less than 0.5 d B and 0.8 d B within bandwidths of 160 GHz and 400 GHz, respectively.展开更多
Estimating the residual heat of blast furnace slag flushing in China,classifying and introducing the current proposed methods of slag flushing waste heat utilization,and listing existing cases.In order to better save ...Estimating the residual heat of blast furnace slag flushing in China,classifying and introducing the current proposed methods of slag flushing waste heat utilization,and listing existing cases.In order to better save energy and water in the slag flushing process of blast furnaces,an ideal comprehensive cascade utilization system scheme for annual recovery of waste heat is proposed.Based on the measured waste heat data of a steel plant,design calculations are carried out to further analyze the economic feasibility of the new scheme and provide reference for its promotion and application.展开更多
Multi-energy complementary distributed energy system(MECDES)is an important development direction for the energy system.It has the advantages of energy conservation and environmental protection and has great potential...Multi-energy complementary distributed energy system(MECDES)is an important development direction for the energy system.It has the advantages of energy conservation and environmental protection and has great potential to realize efficient energy cascade utilization through the energy conversion and utilization of cooling,heating,and power in place,achieving a user-oriented energy supply.The present study thoroughly reviews the current research status and puts forward the key scientific issues that urgently need to be resolved by investigating the problems and challenges of the MECDES from the perspectives of the characterization of the energetic mass-energy potential,the synergistic transformation and energy-potential coupling mechanism of multi-energy complementation,energy quality improvement and storage,and proactive regulation of the MECDES.Furthermore,the latest research progress of the MECDES for trickling the key scientific issues is comprehensively presented by proposing the distributed energy system with the complementation of multi-energy sources,developing novel ways of the energy potential coupling and energy cascaded comprehensive utilization of multi-energy complementation,proposing a new theory of multi-energy complementation and energy potential coupling and a new mechanism of source complementation,processing matching and thermodynamic cycle system collaborative conversion of both the fossil energy and renewable energy,and developing a new method of proactive adjust and control for adapting to fluctuating energy input and various energy load demands.Finally,the prospects and recommendations for the future research and development direction of MECDES are provided.展开更多
New trigeneration system consists of an internal combustion engine,a power and cooling cogeneration system and an absorption heat transformer system.The exhaust gas is recovered by the power and cooling cogeneration s...New trigeneration system consists of an internal combustion engine,a power and cooling cogeneration system and an absorption heat transformer system.The exhaust gas is recovered by the power and cooling cogeneration subsystem producing the cooling and power.The jacket water is recovered by the absorption heat transformer subsystem producing lowpressure steam.The exergy performance and the energy saving performance which is evaluated by the primary energy saving ratio of the new distributed energy system are analyzed.The effects of the ratio of the output power and cooling of the power and cooling cogeneration subsystem and the generator outlet temperature of the absorption heat transformer subsystem to the primary energy saving ratio are considered.The contributions of the subsystems to the primary energy saving ratio are quantified.The maximum primary energy saving ratio of the new distributed energy system is 15.8%,which is 3.9 percentage points higher than that of the conventional distributed energy system due to the cascade utilization of the waste heat from the internal combustion engine.展开更多
A detailed thermal power plant model was developed to evaluate power plant waste heat usage in terms of the operating parameters,energy consumption,water consumption,and pollutant emissions.This model was used to anal...A detailed thermal power plant model was developed to evaluate power plant waste heat usage in terms of the operating parameters,energy consumption,water consumption,and pollutant emissions.This model was used to analyze the bypass flue gas energy cascade utilization design which provides excellent energy savings and emission reductions.This paper then presents a design to use the low-temperature waste heat and to extract water from the flue gas.The low-grade heat can be recovered from a coal-fired unit using absorption heat pumps to increase the air preheating.This method significantly reduces the turbine steam extraction in the low pressure stages which increases the turbine power and reduces the coal consumption.This design has a small heat transfer temperature difference between the air preheater and the air warmer,resulting in a smaller exergy loss.The power output of the present design was 1024.28 MW with a coal consumption savings of 3.69 g·(kWh)^(−1).In addition,the present design extracts moisture out of the flue gas to produce 46.48 t·h^(−1)of water.The main goal of this work is to provide a theoretical analysis for studying complex thermal power plant systems and various energy conservation and CO_(2)reduction options for conventional power plants.展开更多
The high-frequency pulse tube cryocooler(HPTC)has been attracting increasing and widespread attention in the field of cryogenic technology because of its compact structure,low vibration,and reliable operation.The gas-...The high-frequency pulse tube cryocooler(HPTC)has been attracting increasing and widespread attention in the field of cryogenic technology because of its compact structure,low vibration,and reliable operation.The gas-coupled HPTC,driven by a single compressor,is currently the simplest and most compact structure.For HPTCs operating below 20 K,in order to obtain the mW cooling capacity,hundreds or even thousands of watts of electrical power are consumed,where radiation heat leakage accounts for a large proportion of their cooling capacity.In this paper,based on SAGE10,a HPTC heat radiation calculation model was first established to study the effects of radiation heat leakage on apparent performance parameters(such as temperature and cooling capacity),and internal parameters(such as enthalpy flow and gas distribution)of the gas-coupled HPTC.An active thermal insulation method of cascade utilization of the cold energy of the system was proposed for the gas-coupled HPTC.Numerical simulations indicate that the reduction of external radiation heat leakage cannot only directly increase the net cooling power,but also decrease the internal gross losses and increase the mass and acoustic power in the lower-temperature section,which further enhances the refrigeration performance.The numerical calculation results were verified by experiments,and the test results showed that the no-load temperature of the developed cryocooler prototype decreased from 15.1 K to 6.4 K,and the relative Carnot efficiency at 15.5 K increased from 0.029%to 0.996%when substituting the proposed active method for the traditional passive method with multi-layer thermal insulation materials.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 coal partial gasification process produces a large number of chars.They have similar combustion characteristics to anthracite and can be utilized as a material manufacturing clean briquette to replace residential ...The coal partial gasification process produces a large number of chars.They have similar combustion characteristics to anthracite and can be utilized as a material manufacturing clean briquette to replace residential coal to achieve clean combustion.Moreover,the coal partial gasification produced more tar at relatively low temperature,which can be applied as naphtha or diesel after purification and hydrogenation.Herein,experiments of coal partial gasification coproducing char,tar,and gas are carried out on a bench-scale fluidized bed reactor during the temperature range of 625–762℃.The effect of equivalence ratio on the characteristics of coal partial gasification products is studied.The results show that the equivalence ratio increasing from 0.06 to 0.13 leads to a higher partial gasification temperature and lower char yield,and tar yield reaches a maximum value and the lower calorific value of gas reaches as high as 6.14 MJ/m^(3).When the gasification temperature is lower than 643℃,the increase in temperature promotes the generation of oxygen-containing functional groups and aromatic compounds in coal particles,and the microstructures of char become more disordered.The combustion stability of char is getting worse,whereas the pore structures in char become abundant at high temperatures.From the analysis of the tar chromatography column,it is observed that asphaltene and non-hydrocarbon account for 77%–88%of the total amount of tar.展开更多
Traditional condensing air-conditioning systems consume large amounts of energy in hot and humid areas,and it is difficult to achieve simultaneous control of temperature and humidity.A combined absorption refrigeratio...Traditional condensing air-conditioning systems consume large amounts of energy in hot and humid areas,and it is difficult to achieve simultaneous control of temperature and humidity.A combined absorption refrigeration(AR)and liquid desiccant dehumidification(LDD)air-conditioning system based on cascade utilization of low-grade heat source is proposed.The system can realize independent control of temperature and humidity and carry out profound recovery of low-grade heat sources.Under the design conditions,the heat utilization rate C reaches 21.05%,which is 2.73 times that of the conventional absorption refrigeration reference system.A parametric sensitivity analysis is performed to optimize the system.The C increases from 9.79%to 18.55%and the coefficient of performance C O P t increases from 0.33 to 0.35 with an increase in chilled water temperature from 7°C to 15°C.With an increase in regenerant solution temperature from 60°C to 70°C,the C achieves the optimal value of 21.05%at 68°C.C decreases from 21.05%to 15.05%as the concentration of the regenerant solution increases from 36%to 40%.Under variable environmental temperature and humidity,the C the proposed system changes within a small range and stays much higher than that of the reference system with the same quality heat source,which indicates that the proposed system has a better adaptability to changing environmental parameters.展开更多
A new cleaner power generation system(IPGS) is proposed and investigated in this paper. Integrating combined cycle with supercritical water gasification of coal, the thermodynamic energy of the produced syngas is casc...A new cleaner power generation system(IPGS) is proposed and investigated in this paper. Integrating combined cycle with supercritical water gasification of coal, the thermodynamic energy of the produced syngas is cascade utilized according to its temperature and pressure, both sensible and latent heat of the syngas can be recycled into the system, and thereby the net power efficiency can be about 6.4 percentage points higher than that of the traditional GE gasification based power plant(GEPP). The exergy analysis results show that the exergy efficiency of the proposed system reaches 52.45%, which is 13.94% higher than that of the GEPP, and the improvement in exergy efficiency of the proposed system mainly comes from the exergy destruction decline in the syngas energy recovery process, the condensation process and the syngas purification process. The syngas combustion process is the highest exergy destruction process with a value of 157.84 MW in the proposed system. Further performance improvement of the proposed system lies in the utilization process of syngas. Furthermore, system operation parameters have been examined on the coal mass fraction in the supercritical water gasifier(GF), the gasification temperature, and the gasification pressure. The parametric analysis shows that changes in coal concentration in the GF exert more influence on the exergy efficiency of the system compared with the other two parameters.展开更多
We experimentally demonstrate a cascaded Raman scattering continuum, utilizing a compact mode-locked Yb-doped fiber laser based on a nonlinear polarization rotation technique in the all normal dispersion regime.There ...We experimentally demonstrate a cascaded Raman scattering continuum, utilizing a compact mode-locked Yb-doped fiber laser based on a nonlinear polarization rotation technique in the all normal dispersion regime.There is no physical filter or polarization controller in the oscillator, and a different mode-locked operation is achieved, corresponding to the extra fiber location in the oscillator. The broadband spectrum generation owes to the enhanced stimulated Raman scattering progress. The maximum output average power and peak power are14.75 n J and 18.0 W, and the short coherence light is suited for optical coherence tomography.展开更多
基金the Science and Technology Foundation of Shaanxi Province (No.2002K08-G9).
文摘Two novel thermal cycles based on Brayton cycle and Rankine cycle are proposed, respectively, which integrate the recovery of low-level waste heat and Liquefied Nature Gas （LNG） cold energy utilization for power generation. Cascade utilization of energy is realized in the two thermal cycles, where low-level waste heat,low-temperature exergy and pressure exergy of LNG are utilized efficiently through the system synthesis. The simulations are carried out using the commercial Aspen Plus 10.2, and the results are analyzed. Compared with the conventional Brayton cycle and Rankine cycle, the two novel cycles bring 60.94% and 60% in exergy efficiency, respectively and 53.08% and 52.31% in thermal efficiency, respectively.
基金s supported by the Fundamental Research Funds for National Natural Science Foundation of China(W2412102 and 52376063),Central Universities of Hohai University(B220203014)Ningbo Natural Science Foundation(2023J251)China Postdoctoral Science Foundation funded project(2019M651682).
文摘Modulating the macro/nanoarchitecture of evaporators to effectively harness diverse renewable energy sources is of paramount importance for optimizing the performance of solar-driven interfacial evaporation.Inspired by the geometric structure of a windmill,we designed an innovative solar evaporator that expertly harnesses both strong and weak convection.During the purification of heavy metal wastewater,the maximum evaporation rate can reach 4.95 kg m^(−2)h^(−1)under one sun irradiation by introducing an ultralow wind flow(0.1 m s^(−1)),yielding an evaporation rate that is twice that of traditional evaporators.However,the gradual deposition of inorganic salt sediments on the evaporator surface is clearly observable.To address this issue,we present several innovative proof-of-concept cascade treatments that significantly extend the evaporator’s operational lifespan.The innovative design and exceptional performance of this solar evaporator open avenues for advancements in sustainable water treatment,energy generation,and environmental remediation.
基金Project supported by the Special Fund for Basic Scientific Researches of Central Universities“Study on the Ignition Mechanism of Pulverized Coal under High Pressure O_(2)/CO_(2)Atmosphere”(No.:2017KFYXJJ214).
文摘At present,the oxy-fuel combustion(O_(2)/CO_(2)circulating combustion)is dominant in natural gas generating systems,but it consumes much energy for air separation oxygen generation and carbon capture,leading to a severe reduction of generating efficiency.The O_(2)/H_(2)O combustion system,as the new generation of an oxy-combustion system,is superior to the oxy-fuel combustion,and its pollutant emission is lower,but during its combustion,air separation oxygen generation is still needed,so CO_(2)compression energy consumption is still higher.In this paper,a set of carbon capture system applying LNG cold energy to the O_(2)/H_(2)O combustion was developed,and its mathematical model was established to calculate thermal efficiency and exergy efficiency.And then,it was compared with the COOLCEP system which also makes use of LNG cold energy for carbon capture.The combustion process of this system is operated under high pressure with H_(2)O as the circulation medium,and LNG is utilized in a cascading pattern,so the energy consumption of air separation oxygen generation and carbon capture system is reduced,the generating efficiency of the system is increased and carbon capture is conducted at low cost.The thermal efficiency and energy efficiency of this system increase continuously as the inlet temperature of gas turbine rises.When the flow rate of circulating water is 13.5 kmol/s,the combustion pressure is 1.6 MPa,and the inlet temperature of gas turbine reaches 1328.1℃,the thermal efficiency and exergy efficiency is 57.9%(maximum)and 42.7%,respectively.Compared with COOLCEP system,the O_(2)/H_(2)O combustion system is much lower in energy consumption and its thermal efficiency and exergy efficiency are 6.3%and 5.4%higher,respectively.
基金funded by 2017 Research Project of Tianjin Sino-German University of Applied Sciences(Project No.zdkt2017-001)The Science&Technology Development Fund of Tianjin Education Commission for Higher Education(Project No.2018KJ260)The Science&Technology Development Fund of Tianjin Education Commission for Higher Education(Project No.2020ZD03).
文摘This paper briefly summarizes the current status of typical solar thermal power plant system,including system composition,thermal energy storage medium and performance.The thermo-physical properties of the storage medium are some of the most important factors that affect overall efficiency of the system,because some renewable energy sources such as solar and wind are unpredictable.A thermal storage system is therefore necessary to store energy for continuous usage.Based on the form of storage or the mode of system connection,heat exchangers of a thermal storage system can produce different temperature ranges of heat transfer fluid to realize energy cascade utilization.Founded upon the review,a small hybrid energy system with a molten-salt energy storage system is proposed to solve the problems of heating,cooling,and electricity consumption of a 1000 m2 training hall at school.The system uses molten-salt storage tank,water tank and steam generator to change the temperature of heat transfer fluid,in order to realize thermal energy cascade utilization.Compared to the existing heating and cooling system,the proposed system needs more renewable energy and less municipal energy to achieve the same results according to simulation analysis.Furthermore,by improving the original heating and cooling system,PMV has been improved.The comprehensive efficiency of solar energy utilization has been increased to 83%.
基金supported by the National Natural Science Foundation of China(No.61571251)the Public Technical Application Research Project of Zhejiang(No.2015C34004)+2 种基金the Discipline Open Fund Project of Zhejiang(No.xkxl1534)the National Education Research of Information Technology(No.146232081)the K.C.Wong Magna Fund in Ningbo University
文摘We propose and demonstrate a simplified and tunable frequency interval optical frequency comb(OFC) generator based on a dual-drive Mach-Zehnder modulator(DD-MZM) using a single continuous-wave(CW) laser and low-power radio frequency(RF) driven signal. A mathematical model for the scheme is established. The 21-and 29-mode OFCs with frequency interval ranging from 6 GHz to 40 GHz are obtained under DD-MZM driven by a low-power RF signal within a maximum bandwidth of 1.12 THz. The generated OFCs exhibit spectral flatnesses of less than 0.5 d B and 0.8 d B within bandwidths of 160 GHz and 400 GHz, respectively.
文摘Estimating the residual heat of blast furnace slag flushing in China,classifying and introducing the current proposed methods of slag flushing waste heat utilization,and listing existing cases.In order to better save energy and water in the slag flushing process of blast furnaces,an ideal comprehensive cascade utilization system scheme for annual recovery of waste heat is proposed.Based on the measured waste heat data of a steel plant,design calculations are carried out to further analyze the economic feasibility of the new scheme and provide reference for its promotion and application.
基金supported by the Major Program of the National Natural Science Foundation of China(Grant No.52090060)。
文摘Multi-energy complementary distributed energy system(MECDES)is an important development direction for the energy system.It has the advantages of energy conservation and environmental protection and has great potential to realize efficient energy cascade utilization through the energy conversion and utilization of cooling,heating,and power in place,achieving a user-oriented energy supply.The present study thoroughly reviews the current research status and puts forward the key scientific issues that urgently need to be resolved by investigating the problems and challenges of the MECDES from the perspectives of the characterization of the energetic mass-energy potential,the synergistic transformation and energy-potential coupling mechanism of multi-energy complementation,energy quality improvement and storage,and proactive regulation of the MECDES.Furthermore,the latest research progress of the MECDES for trickling the key scientific issues is comprehensively presented by proposing the distributed energy system with the complementation of multi-energy sources,developing novel ways of the energy potential coupling and energy cascaded comprehensive utilization of multi-energy complementation,proposing a new theory of multi-energy complementation and energy potential coupling and a new mechanism of source complementation,processing matching and thermodynamic cycle system collaborative conversion of both the fossil energy and renewable energy,and developing a new method of proactive adjust and control for adapting to fluctuating energy input and various energy load demands.Finally,the prospects and recommendations for the future research and development direction of MECDES are provided.
基金This work was supported in part by the National Basic Research Program of China(No.2014CB249202)International Science&Technology Cooperation Program of China(No.S2014GR03880).
文摘New trigeneration system consists of an internal combustion engine,a power and cooling cogeneration system and an absorption heat transformer system.The exhaust gas is recovered by the power and cooling cogeneration subsystem producing the cooling and power.The jacket water is recovered by the absorption heat transformer subsystem producing lowpressure steam.The exergy performance and the energy saving performance which is evaluated by the primary energy saving ratio of the new distributed energy system are analyzed.The effects of the ratio of the output power and cooling of the power and cooling cogeneration subsystem and the generator outlet temperature of the absorption heat transformer subsystem to the primary energy saving ratio are considered.The contributions of the subsystems to the primary energy saving ratio are quantified.The maximum primary energy saving ratio of the new distributed energy system is 15.8%,which is 3.9 percentage points higher than that of the conventional distributed energy system due to the cascade utilization of the waste heat from the internal combustion engine.
基金The authors acknowledge financial support from the National Natural Science Foundation of China(No.51876057)the NSFC Projects of International Cooperation and Exchanges(No.52061125101)the Fundamental Research Funds for the Central Universities(No.2022JG006).
文摘A detailed thermal power plant model was developed to evaluate power plant waste heat usage in terms of the operating parameters,energy consumption,water consumption,and pollutant emissions.This model was used to analyze the bypass flue gas energy cascade utilization design which provides excellent energy savings and emission reductions.This paper then presents a design to use the low-temperature waste heat and to extract water from the flue gas.The low-grade heat can be recovered from a coal-fired unit using absorption heat pumps to increase the air preheating.This method significantly reduces the turbine steam extraction in the low pressure stages which increases the turbine power and reduces the coal consumption.This design has a small heat transfer temperature difference between the air preheater and the air warmer,resulting in a smaller exergy loss.The power output of the present design was 1024.28 MW with a coal consumption savings of 3.69 g·(kWh)^(−1).In addition,the present design extracts moisture out of the flue gas to produce 46.48 t·h^(−1)of water.The main goal of this work is to provide a theoretical analysis for studying complex thermal power plant systems and various energy conservation and CO_(2)reduction options for conventional power plants.
基金This work was supported by the National Key R&D Program of China(Grant No.2018Y FB0504603)the National Natural Science Foundation of China(Grant No.U1831203)+2 种基金the Strategic Pilot Projects in Space Science of China(Grant No.XDA15010400)the Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(Grant No.QYZDY-SSW-JSC028)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2019030).
文摘The high-frequency pulse tube cryocooler(HPTC)has been attracting increasing and widespread attention in the field of cryogenic technology because of its compact structure,low vibration,and reliable operation.The gas-coupled HPTC,driven by a single compressor,is currently the simplest and most compact structure.For HPTCs operating below 20 K,in order to obtain the mW cooling capacity,hundreds or even thousands of watts of electrical power are consumed,where radiation heat leakage accounts for a large proportion of their cooling capacity.In this paper,based on SAGE10,a HPTC heat radiation calculation model was first established to study the effects of radiation heat leakage on apparent performance parameters(such as temperature and cooling capacity),and internal parameters(such as enthalpy flow and gas distribution)of the gas-coupled HPTC.An active thermal insulation method of cascade utilization of the cold energy of the system was proposed for the gas-coupled HPTC.Numerical simulations indicate that the reduction of external radiation heat leakage cannot only directly increase the net cooling power,but also decrease the internal gross losses and increase the mass and acoustic power in the lower-temperature section,which further enhances the refrigeration performance.The numerical calculation results were verified by experiments,and the test results showed that the no-load temperature of the developed cryocooler prototype decreased from 15.1 K to 6.4 K,and the relative Carnot efficiency at 15.5 K increased from 0.029%to 0.996%when substituting the proposed active method for the traditional passive method with multi-layer thermal insulation materials.
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 Key Research and Development Projects of China(2019YFE0100100-05).
文摘The coal partial gasification process produces a large number of chars.They have similar combustion characteristics to anthracite and can be utilized as a material manufacturing clean briquette to replace residential coal to achieve clean combustion.Moreover,the coal partial gasification produced more tar at relatively low temperature,which can be applied as naphtha or diesel after purification and hydrogenation.Herein,experiments of coal partial gasification coproducing char,tar,and gas are carried out on a bench-scale fluidized bed reactor during the temperature range of 625–762℃.The effect of equivalence ratio on the characteristics of coal partial gasification products is studied.The results show that the equivalence ratio increasing from 0.06 to 0.13 leads to a higher partial gasification temperature and lower char yield,and tar yield reaches a maximum value and the lower calorific value of gas reaches as high as 6.14 MJ/m^(3).When the gasification temperature is lower than 643℃,the increase in temperature promotes the generation of oxygen-containing functional groups and aromatic compounds in coal particles,and the microstructures of char become more disordered.The combustion stability of char is getting worse,whereas the pore structures in char become abundant at high temperatures.From the analysis of the tar chromatography column,it is observed that asphaltene and non-hydrocarbon account for 77%–88%of the total amount of tar.
基金The authors express gratitude for the support of the National Key Research and Development Program of China(No.2018YFB0905103)the National Natural Science Foundation of China(No.51806213)Beijing Key Laboratory of Distributed Combined Cooling Heating and Power System.
文摘Traditional condensing air-conditioning systems consume large amounts of energy in hot and humid areas,and it is difficult to achieve simultaneous control of temperature and humidity.A combined absorption refrigeration(AR)and liquid desiccant dehumidification(LDD)air-conditioning system based on cascade utilization of low-grade heat source is proposed.The system can realize independent control of temperature and humidity and carry out profound recovery of low-grade heat sources.Under the design conditions,the heat utilization rate C reaches 21.05%,which is 2.73 times that of the conventional absorption refrigeration reference system.A parametric sensitivity analysis is performed to optimize the system.The C increases from 9.79%to 18.55%and the coefficient of performance C O P t increases from 0.33 to 0.35 with an increase in chilled water temperature from 7°C to 15°C.With an increase in regenerant solution temperature from 60°C to 70°C,the C achieves the optimal value of 21.05%at 68°C.C decreases from 21.05%to 15.05%as the concentration of the regenerant solution increases from 36%to 40%.Under variable environmental temperature and humidity,the C the proposed system changes within a small range and stays much higher than that of the reference system with the same quality heat source,which indicates that the proposed system has a better adaptability to changing environmental parameters.
基金the financial support of the National Key Research and Development Program of China(Grant No.2016YFB0600105)。
文摘A new cleaner power generation system(IPGS) is proposed and investigated in this paper. Integrating combined cycle with supercritical water gasification of coal, the thermodynamic energy of the produced syngas is cascade utilized according to its temperature and pressure, both sensible and latent heat of the syngas can be recycled into the system, and thereby the net power efficiency can be about 6.4 percentage points higher than that of the traditional GE gasification based power plant(GEPP). The exergy analysis results show that the exergy efficiency of the proposed system reaches 52.45%, which is 13.94% higher than that of the GEPP, and the improvement in exergy efficiency of the proposed system mainly comes from the exergy destruction decline in the syngas energy recovery process, the condensation process and the syngas purification process. The syngas combustion process is the highest exergy destruction process with a value of 157.84 MW in the proposed system. Further performance improvement of the proposed system lies in the utilization process of syngas. Furthermore, system operation parameters have been examined on the coal mass fraction in the supercritical water gasifier(GF), the gasification temperature, and the gasification pressure. The parametric analysis shows that changes in coal concentration in the GF exert more influence on the exergy efficiency of the system compared with the other two parameters.
基金supported by the National Natural Science Foundation of China(No.61575011)the Key Project of the National Natural Science Foundation of China(No.61235010)
文摘We experimentally demonstrate a cascaded Raman scattering continuum, utilizing a compact mode-locked Yb-doped fiber laser based on a nonlinear polarization rotation technique in the all normal dispersion regime.There is no physical filter or polarization controller in the oscillator, and a different mode-locked operation is achieved, corresponding to the extra fiber location in the oscillator. The broadband spectrum generation owes to the enhanced stimulated Raman scattering progress. The maximum output average power and peak power are14.75 n J and 18.0 W, and the short coherence light is suited for optical coherence tomography.
