A three-way catalyst comprised novel oxygen storage components for emission control in natural gas powered engines was prepared. The addition of novel oxygen storage components to the Pd/γ-Al2O3 catalysts resulted ...A three-way catalyst comprised novel oxygen storage components for emission control in natural gas powered engines was prepared. The addition of novel oxygen storage components to the Pd/γ-Al2O3 catalysts resulted in improved activities of the fresh and aged catalyst by lowering the light-off temperature for methane in natural gas engines exhaust.展开更多
This work illustrates the steady state, two dimensional natural convective flow and heat transfer features in square enclosure containing heated hexagonal block maintained either at constant wall temperature(CWT) or u...This work illustrates the steady state, two dimensional natural convective flow and heat transfer features in square enclosure containing heated hexagonal block maintained either at constant wall temperature(CWT) or uniform heat flux(UHF) thermal conditions. Governing equations(mass, momentum and energy) are solved by using finite volume method(FVM) with 3rd order accurate QUICK discretization scheme and SIMPLE algorithm for range of field pertinent parameters such as, Grashof number(10~3≤ Gr ≤ 10~6), Prandtl number(1 ≤ Pr ≤ 100) and power law index(0.5 ≤ n ≤ 1.5). The analysis of momentum and heat transfer characteristics are delineated by evolution of streamlines, isotherms, variation of average Nusselt number value and Colburn factor for natural convection(j_(nH)). A remarkable change is observed on fluid flow and thermal distribution pattern in cavity for both thermal conditions. Nusselt number shows linear variation with Grashof and Prandtl numbers; while rate of heat transfer by convection decreases for power law index value. Higher heat transfer rate can be achieved by using uniform heat flux condition. A Nusselt number correlation is developed for possible utilization in engineering/scientific design purpose.展开更多
The year 2017 saw explosive growth in China's natural gas market, and the apparent consumption was 235.7 billion cubic meters, up 18.2% over the same period of 2016. In 2017, China's domestic production growth...The year 2017 saw explosive growth in China's natural gas market, and the apparent consumption was 235.7 billion cubic meters, up 18.2% over the same period of 2016. In 2017, China's domestic production growth picked up significantly, reaching 145.3 billion cubic meters, an increase of 9%.Natural gas imports grew rapidly, and imported pipeline gas and imported LNG totaled 91.6 billion cubic meters. The trade volume of LNG surpassed that of pipeline gas for the first time since 2012. In 2018, the macro-economy is expected to maintain growth at a moderate-to-high rate. However, driven by favorable factors such as environmental policies, China's demand for natural gas is expected to continue to grow rapidly, and natural gas consumption will maintain double-digit growth, roughly at 12%. Nevertheless, the seasonable imbalance between natural gas supply and demand will remain conspicuous.展开更多
At the 75th UN General Assembly,the Chinese government declared to strive to reach peak carbon dioxide emission by 2030 and achieve“carbon neutrality”by 2060.The establishment of this goal not only brings opportunit...At the 75th UN General Assembly,the Chinese government declared to strive to reach peak carbon dioxide emission by 2030 and achieve“carbon neutrality”by 2060.The establishment of this goal not only brings opportunities but also challenges to the development of China's natural gas industry.In order to comprehensively understand the whole chain of China's natural gas industry under the goal of“carbon peak and carbon neutrality”,this paper sorts out the recent related research results and discusses the development prospect of China's natural gas industry in the background of“carbon neutrality”.And the following research results are obtained.First,compared with other low-carbon or carbon-free energies,the foundation for the large-scale stable supply of natural gas in China is the most solid,so natural gas is the most practical option to replace coal and realize“low carbon”.Second,in the process of“carbon neutrality”,natural gas will play an important role in different stages.Finally,several suggestions are proposed to promote the development of China's natural gas industry.First,it is necessary to further strengthen the construction of natural gas infrastructure,especially the construction of emergency peak shaving capacity.Second,market-oriented pipe capacity distribution and two-part pricing will be the reform direction of the operation mode of natural gas pipeline network,but they shall be promoted gradually and appropriately according to the development degree of China's natural gas industry.Third,under the goal of“carbon neutrality”,much attention shall be paid to the development of natural gas fired power generation,especially the development of peak-shaving gas power.Fourth,it is necessary to sufficiently grasp the opportunity period and window period of industry development and strengthen cooperation among upstream,middle and downstream to jointly promote the healthy development of China's natural gas industry.展开更多
Regarding the state's policy that gives a higher on-grid electricity price to natural gas CHP (combined heat and power) projects, this paper studies the effect of it on the operation of those projects by theoretic...Regarding the state's policy that gives a higher on-grid electricity price to natural gas CHP (combined heat and power) projects, this paper studies the effect of it on the operation of those projects by theoretical analysis and a case study. It concludes that on-grid electricity price on the high side, compared to heat price, will lead power plants to produce more electricity but less heat, thus causing decrease of the plants' thermal eff iciency and harm to energy saving of the whole society.展开更多
Followed by the revival in 2016,an explosive growth appeared in the 2017 natural gas market in China,with an annual consumption being up to 233.5 billion cubic meters(bcm)and annual increment being up to 35.3 bcm.In v...Followed by the revival in 2016,an explosive growth appeared in the 2017 natural gas market in China,with an annual consumption being up to 233.5 billion cubic meters(bcm)and annual increment being up to 35.3 bcm.In view of this,it is necessary to analyze the main reasons for that and predict its sustainability in the future.This study demonstrates that(1)such an explosive growth in 2017 mainly benefits from many aspects like the improved macroeconomic situation,deep implementation of air pollution prevention and control measures,price rising of bulk commodities such as petrochemical products,increasing load on natural gas-fueled power generation in East China,rather low prices of pipeline gas,and so on;and(2)natural gas market will be rapidly developed due to the support from the present economic developing trend,the coal-to-gas promotion,orientation of policies implementation,oil and gas prices potential,and so on,but on the other hand,it will be restricted by limited resources,incomplete infrastructure conditions,etc.It is concluded that(1)natural gas demand potential before 2020 will be kept rising but its annual increment will be difficult to remain at 30 bcm;(2)industrial fuels and gas-fueled power generation will be the future target for natural gas market development,and(3)the Circum-Bohai Sea Regions will be the key zone for the natural gas demand soaring potential.To maintain such a satisfying developing trend,we put forward the following proposals:to expand natural gas supply and exploit more substantial natural gas resources home and abroad;to improve infrastructure construction and to plan,design and construct more pipeline networks,LNG terminals,peak-shaving facilities such as underground gas storages all over China;and to make natural gas prices more reasonable and fair with the co-existence of residents and non-residents pricing mechanism,ensuring that the price plays a role of leverage between supply and demand without any administrative interferences.展开更多
China-Africa cooperation in renewable energy can accelerate Africa＇sgreen industrializationONCE the sun sets over Sub-Saharan Africa,switching on the lights is easier said than done.Much of the region remains cloaked...China-Africa cooperation in renewable energy can accelerate Africa＇sgreen industrializationONCE the sun sets over Sub-Saharan Africa,switching on the lights is easier said than done.Much of the region remains cloaked in darkness until daybreak.In2015,Sub-Saharan Africa had more than 635 million people living without access to electricity,mostly in rural areas.according to the International Energy Agency （IEA）.展开更多
The increasing adoption of gas-fired power plants directly strengthens the coupling between electric power and natural gas systems. Current industrial practice in optimal power flow for electric power systems has not ...The increasing adoption of gas-fired power plants directly strengthens the coupling between electric power and natural gas systems. Current industrial practice in optimal power flow for electric power systems has not taken the security constraints of gas systems into consideration, resulting in an overly-optimistic solution. Meanwhile, the operation of electric power and natural gas systems is coupled over multiple periods because of the ramp rate limits of power generators and the slow dynamical characteristics of gas systems. Based on these motivations, we propose a multi-period integrated natural gas and electric power system probabilistic optimal power flow(M-GEPOPF) model, which includes dynamic gas flow models. To address the uncertainties originating from wind power and load forecasting, a probabilistic optimal power flow(POPF) calculation based on a three-point estimate method(3 PEM) is adopted. Moreover, power-togas(Pt G) units are employed to avoid wind power curtailment and enable flexible bi-directional energy flows between the coupled energy systems. An integrated IEEE RTS 24-bus electric power system and the Belgian 20-node natural gas system are employed as a test case to verify the applicability of the proposed M-GEPOPF model, and to demonstrate the potential economic benefits of Pt G units.展开更多
Assessing the reliability of integrated electricity and gas systems has become an important issue due to the strong dependence of these energy networks through the power-to-gas(P2G)and combined heat and power(CHP)tech...Assessing the reliability of integrated electricity and gas systems has become an important issue due to the strong dependence of these energy networks through the power-to-gas(P2G)and combined heat and power(CHP)technologies.The current work,initially,presents a detailed energy flow model for the integrated power and natural gas system in light of the P2G and CHP technologies.Considering the simultaneous load flow of networks,a contingency analysis procedure is proposed,and reliability is assessed through sequential Monte Carlo simulations.The current study examines the effect of independent and dependent operation of energy networks on the reliability of the systems.In particular,the effect of employing both P2G and CHP technologies on reliability criteria is evaluated.In addition,a series of sensitivity analysis are performed on the size and site of these technologies to investigate their effects on system reliability.The proposed method is implemented on an integrated IEEE 24-bus electrical power system and 20-node Belgian natural gas system.The simulation procedure certifies the proposed method for reliability assessment is practical and applicable.In addition,the results prove connection between energy networks through P2G and CHP technologies can improve reliability of networks if the site and size of technologies are properly determined.展开更多
Liquefied natural gas （LNG）, an increasingly widely applied clean fuel, releases a large number of cold energy in its regasification process. In the present paper, the existing power generation cycles utilizing LNG ...Liquefied natural gas （LNG）, an increasingly widely applied clean fuel, releases a large number of cold energy in its regasification process. In the present paper, the existing power generation cycles utilizing LNG cold energy are introduced and summarized. The direction of cycle improvement can be divided into the key factors affecting basic power generation cycles and the structural enhancement of cycles utilizing LNG cold energy. The former includes the effects of LNG-side parameters, working fluids, and inlet and outlet thermodynamic parameters of equipment, while the latter is based on Rankine cycle, Brayton cycle, Kalina cycle and their compound cycles. In the present paper, the diversities of cryogenic power generation cycles utilizing LNG cold energy are discussed and analyzed. It is pointed out that further researches should focus on the selection and component matching of organic mixed working fluids and the combination of process simulation and experi- mental investigation, etc.展开更多
基金the National Natural Science Foundation of China(No:20273043)the Ministry of Education of China for providing financial support for this project
文摘A three-way catalyst comprised novel oxygen storage components for emission control in natural gas powered engines was prepared. The addition of novel oxygen storage components to the Pd/γ-Al2O3 catalysts resulted in improved activities of the fresh and aged catalyst by lowering the light-off temperature for methane in natural gas engines exhaust.
文摘This work illustrates the steady state, two dimensional natural convective flow and heat transfer features in square enclosure containing heated hexagonal block maintained either at constant wall temperature(CWT) or uniform heat flux(UHF) thermal conditions. Governing equations(mass, momentum and energy) are solved by using finite volume method(FVM) with 3rd order accurate QUICK discretization scheme and SIMPLE algorithm for range of field pertinent parameters such as, Grashof number(10~3≤ Gr ≤ 10~6), Prandtl number(1 ≤ Pr ≤ 100) and power law index(0.5 ≤ n ≤ 1.5). The analysis of momentum and heat transfer characteristics are delineated by evolution of streamlines, isotherms, variation of average Nusselt number value and Colburn factor for natural convection(j_(nH)). A remarkable change is observed on fluid flow and thermal distribution pattern in cavity for both thermal conditions. Nusselt number shows linear variation with Grashof and Prandtl numbers; while rate of heat transfer by convection decreases for power law index value. Higher heat transfer rate can be achieved by using uniform heat flux condition. A Nusselt number correlation is developed for possible utilization in engineering/scientific design purpose.
文摘The year 2017 saw explosive growth in China's natural gas market, and the apparent consumption was 235.7 billion cubic meters, up 18.2% over the same period of 2016. In 2017, China's domestic production growth picked up significantly, reaching 145.3 billion cubic meters, an increase of 9%.Natural gas imports grew rapidly, and imported pipeline gas and imported LNG totaled 91.6 billion cubic meters. The trade volume of LNG surpassed that of pipeline gas for the first time since 2012. In 2018, the macro-economy is expected to maintain growth at a moderate-to-high rate. However, driven by favorable factors such as environmental policies, China's demand for natural gas is expected to continue to grow rapidly, and natural gas consumption will maintain double-digit growth, roughly at 12%. Nevertheless, the seasonable imbalance between natural gas supply and demand will remain conspicuous.
文摘At the 75th UN General Assembly,the Chinese government declared to strive to reach peak carbon dioxide emission by 2030 and achieve“carbon neutrality”by 2060.The establishment of this goal not only brings opportunities but also challenges to the development of China's natural gas industry.In order to comprehensively understand the whole chain of China's natural gas industry under the goal of“carbon peak and carbon neutrality”,this paper sorts out the recent related research results and discusses the development prospect of China's natural gas industry in the background of“carbon neutrality”.And the following research results are obtained.First,compared with other low-carbon or carbon-free energies,the foundation for the large-scale stable supply of natural gas in China is the most solid,so natural gas is the most practical option to replace coal and realize“low carbon”.Second,in the process of“carbon neutrality”,natural gas will play an important role in different stages.Finally,several suggestions are proposed to promote the development of China's natural gas industry.First,it is necessary to further strengthen the construction of natural gas infrastructure,especially the construction of emergency peak shaving capacity.Second,market-oriented pipe capacity distribution and two-part pricing will be the reform direction of the operation mode of natural gas pipeline network,but they shall be promoted gradually and appropriately according to the development degree of China's natural gas industry.Third,under the goal of“carbon neutrality”,much attention shall be paid to the development of natural gas fired power generation,especially the development of peak-shaving gas power.Fourth,it is necessary to sufficiently grasp the opportunity period and window period of industry development and strengthen cooperation among upstream,middle and downstream to jointly promote the healthy development of China's natural gas industry.
文摘Regarding the state's policy that gives a higher on-grid electricity price to natural gas CHP (combined heat and power) projects, this paper studies the effect of it on the operation of those projects by theoretical analysis and a case study. It concludes that on-grid electricity price on the high side, compared to heat price, will lead power plants to produce more electricity but less heat, thus causing decrease of the plants' thermal eff iciency and harm to energy saving of the whole society.
文摘Followed by the revival in 2016,an explosive growth appeared in the 2017 natural gas market in China,with an annual consumption being up to 233.5 billion cubic meters(bcm)and annual increment being up to 35.3 bcm.In view of this,it is necessary to analyze the main reasons for that and predict its sustainability in the future.This study demonstrates that(1)such an explosive growth in 2017 mainly benefits from many aspects like the improved macroeconomic situation,deep implementation of air pollution prevention and control measures,price rising of bulk commodities such as petrochemical products,increasing load on natural gas-fueled power generation in East China,rather low prices of pipeline gas,and so on;and(2)natural gas market will be rapidly developed due to the support from the present economic developing trend,the coal-to-gas promotion,orientation of policies implementation,oil and gas prices potential,and so on,but on the other hand,it will be restricted by limited resources,incomplete infrastructure conditions,etc.It is concluded that(1)natural gas demand potential before 2020 will be kept rising but its annual increment will be difficult to remain at 30 bcm;(2)industrial fuels and gas-fueled power generation will be the future target for natural gas market development,and(3)the Circum-Bohai Sea Regions will be the key zone for the natural gas demand soaring potential.To maintain such a satisfying developing trend,we put forward the following proposals:to expand natural gas supply and exploit more substantial natural gas resources home and abroad;to improve infrastructure construction and to plan,design and construct more pipeline networks,LNG terminals,peak-shaving facilities such as underground gas storages all over China;and to make natural gas prices more reasonable and fair with the co-existence of residents and non-residents pricing mechanism,ensuring that the price plays a role of leverage between supply and demand without any administrative interferences.
文摘China-Africa cooperation in renewable energy can accelerate Africa＇sgreen industrializationONCE the sun sets over Sub-Saharan Africa,switching on the lights is easier said than done.Much of the region remains cloaked in darkness until daybreak.In2015,Sub-Saharan Africa had more than 635 million people living without access to electricity,mostly in rural areas.according to the International Energy Agency （IEA）.
基金supported by the National Natural Science Foundation of China(No.51277052,No.51407125)
文摘The increasing adoption of gas-fired power plants directly strengthens the coupling between electric power and natural gas systems. Current industrial practice in optimal power flow for electric power systems has not taken the security constraints of gas systems into consideration, resulting in an overly-optimistic solution. Meanwhile, the operation of electric power and natural gas systems is coupled over multiple periods because of the ramp rate limits of power generators and the slow dynamical characteristics of gas systems. Based on these motivations, we propose a multi-period integrated natural gas and electric power system probabilistic optimal power flow(M-GEPOPF) model, which includes dynamic gas flow models. To address the uncertainties originating from wind power and load forecasting, a probabilistic optimal power flow(POPF) calculation based on a three-point estimate method(3 PEM) is adopted. Moreover, power-togas(Pt G) units are employed to avoid wind power curtailment and enable flexible bi-directional energy flows between the coupled energy systems. An integrated IEEE RTS 24-bus electric power system and the Belgian 20-node natural gas system are employed as a test case to verify the applicability of the proposed M-GEPOPF model, and to demonstrate the potential economic benefits of Pt G units.
文摘Assessing the reliability of integrated electricity and gas systems has become an important issue due to the strong dependence of these energy networks through the power-to-gas(P2G)and combined heat and power(CHP)technologies.The current work,initially,presents a detailed energy flow model for the integrated power and natural gas system in light of the P2G and CHP technologies.Considering the simultaneous load flow of networks,a contingency analysis procedure is proposed,and reliability is assessed through sequential Monte Carlo simulations.The current study examines the effect of independent and dependent operation of energy networks on the reliability of the systems.In particular,the effect of employing both P2G and CHP technologies on reliability criteria is evaluated.In addition,a series of sensitivity analysis are performed on the size and site of these technologies to investigate their effects on system reliability.The proposed method is implemented on an integrated IEEE 24-bus electrical power system and 20-node Belgian natural gas system.The simulation procedure certifies the proposed method for reliability assessment is practical and applicable.In addition,the results prove connection between energy networks through P2G and CHP technologies can improve reliability of networks if the site and size of technologies are properly determined.
文摘Liquefied natural gas （LNG）, an increasingly widely applied clean fuel, releases a large number of cold energy in its regasification process. In the present paper, the existing power generation cycles utilizing LNG cold energy are introduced and summarized. The direction of cycle improvement can be divided into the key factors affecting basic power generation cycles and the structural enhancement of cycles utilizing LNG cold energy. The former includes the effects of LNG-side parameters, working fluids, and inlet and outlet thermodynamic parameters of equipment, while the latter is based on Rankine cycle, Brayton cycle, Kalina cycle and their compound cycles. In the present paper, the diversities of cryogenic power generation cycles utilizing LNG cold energy are discussed and analyzed. It is pointed out that further researches should focus on the selection and component matching of organic mixed working fluids and the combination of process simulation and experi- mental investigation, etc.
