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    25 October 2021, Volume 43 Issue 10
    Investigation and analysis on carbon emission status in China on the path to carbon neutrality
    ZHANG Junfeng, XU Wenjuan, WANG Yueqi, YIN Yan, XIE Hui, LIANG Xingyu, ZHAO Jun
    2021, 43(10):  1-10.  doi:10.3969/j.issn.1674-1951.2021.10.001
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    Co-ordinating energy structure and regulating energy market are powerful tools for China to achieve carbon peaking and carbon neutrality by 2030 and 2060.To complete the target,it is necessary to conduct a comprehensive investigation on energy structures and carbon emission patterns of various regions,and explore the key factors affecting energy structure transformation.According to geographic environment,economy,energy and other factors,China can be divided into four regions:the North Corridor (the traditional energy storehouse),the Important Industry Area (energy-intense industrial areas),the East Group (the major energy customer) and the Green Zone(the clean energy treasure-house). By analyzing the energy history in the regions above,three “unbalanced” issues are considered to be solved,which are unreasonable proportions of traditional fossil energy and clean energy,the unbalance between energy supply and demand in space,and the disparate development of green energy and high-quality GDP.Therefore,three suggestions are put forward in order to take economic and environmental benefits into account:connecting GDPs to total carbon emissions;setting GDP weight coefficient,namely "GDP grade";registering ID for green energy users and formulating reference pricing standards for them;establishing energy bridges and making energy allocation aiming to balance the energy structure and economic development and realizing sustainable development of economic environment in China.

    Analysis on solution for green and low-carbon transformation of thermal power enterprises to achieve carbon peak and carbon neutrality
    ZHAO Guotao, QIAN Guoming, WANG Sheng, DING Quan, ZHU Haidong
    2021, 43(10):  11-21.  doi:10.3969/j.issn.1674-1951.2021.10.002
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    The proposal of carbon peaking and carbon neutrality brings profound changes to the development of energy and power industry, especially on promoting the green and low-carbon transformation of power generation enterprises. Based on the full interpretation of the goals, their impacts on energy industry are analyzed from the perspectives of energy structure adjustment, energy supply, energy consumption, energy informatization and emerging energy technologies. Then, according to the problems existing in the production and operation of thermal power enterprises, the strategies and methods to deal with green and low-carbon transformation are put forward,which include enterprise positioning, renewable energy consumption, energy saving, cost control and enterprise digital transformation, so as to provide reference and ideas for the transformation and development of thermal power enterprises in the future.

    Application analysis and prospect of heat pump technology under the goal of carbon neutrality
    SUN Jian, MA Shicai, HUO Cheng, GE Zhihua, ZHOU Shaoxiang
    2021, 43(10):  22-30.  doi:10.3969/j.issn.1674-1951.2021.10.003
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    Since the proposal of carbon peaking and carbon neutrality has made higher requirements for carbon emission reduction in different industries,the energy structure in China will make important adjustments accordingly.The research focuses on the way to reduce carbon emission in conventional industries and making full use of renewable energy.Among different energy saving and emission reduction technologies,heat pump technology has been widely used in civil,industrial and agricultural areas due to its remarkable performance of energy saving and emission reduction.The applications of heat pump technology in distributed household cooling and heating,centralized heating,agricultural,industrial and energy storage areas have been analyzed comprehensively.The main research direction of heat pump technology will focus on new circulation process,new environmental-friendly working medium,key component development,etc.Heat pump technology will be a significant energy saving and emission reduction technical route under the goals of carbon peaking and carbon neutrality.

    Topic Review
    Research progress of Fe based catalysts for hydrogen-rich gas production from biomass catalytic gasification
    ZHOU Yufeng, WANG Xuetao, LIANG Yanzheng, LUO Shaofeng
    2021, 43(10):  31-42.  doi:10.3969/j.issn.1674-1951.2021.10.004
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    Tar, a by-production from biomass gasification, is a main obstacle that hinders the development of biomass gasification. The main methods of tar removal from gasified biomass can be classified into physical and chemical methods. The catalysts of biomass pyrolysis for hydrogen production were summarized. The catalytic ability, reaction mechanism and performance evaluation of Fe-based catalysts with different oxidation states were analyzed. Then, the influence of oxygen potential, carrier type and interaction between carriers and Fe catalyst on Fe-based catalyst was summarized.The new chemical looping gasification technology was introduced.The performance of Fe-based oxygen carrier in biomass chemical looping gasification and the performance of the new composite Fe-based oxygen carriers added with La, Mn, Ni and other elements were analyzed. The research direction of Fe-based catalysts is made.

    Research progress on biomass power generation in CFB boilers
    ZHANG Kaiping, ZHANG Hongfu, GAO Mingming, WANG Yong, MA Cong
    2021, 43(10):  43-49.  doi:10.3969/j.issn.1674-1951.2021.10.005
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    As a renewable energy,biomass energy can effectively solve the problem of fossil energy shortage,so the research on the development and application technology of biomass energy has gradually become the focus of attention.Biomass energy has a variety of types and application technologies,and its application in the field of thermal power is also increasing.At the same time,biomass power generation technology based on circulating fluidized bed has gradually begun to develop.The recent development of biomass energy in China is briefly introduced,and the existing biomass circulating fluidized bed power generation technology is expounded.The research on the three technologies of direct combustion,direct co-combustion and indirect coupling circulating fluidized bed is mainly discussed.Finally,the problems to be solved in the development of biomass circulating fluidized bed power generation technology and the technology in the 'dual carbon' target development prospects.

    Analysis and prospect of key factors affecting the coupling of municipal sludge combustion and coal-fired power plants
    CHEN Quanxi, FU Jiangtao
    2021, 43(10):  50-60.  doi:10.3969/j.issn.1674-1951.2021.10.006
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    By analyzing the policies and application status of municipal sludge combustion technology coupled with coal-fired power plants,the key factors affecting the co-combustion technology can be summarized as water content,calorific value,sand content, sludge drying and suppression methods for heavy metals,dioxins and other pollutants generated from the co-combustion process.The advantages and disadvantages of various deep dehydration and drying processes for municipal sludge are compared.The technical routes of municipal sludge combustion respectively coupled with pulverized coal boilers and circulating fluidized bed boilers are compared,and the influences of sludge' coupling on different boilers' power generation processes are analyzed.The results show that,to implement the projects of municipal sewage sludge combustion coupled with coal-fired power plants effectively,the sand content in sludge should be reduced in order to alleviate the wear of drying equipment and boilers.Meanwhile,the fly ash and slag produced from the co-combustion should to monitored and treated to control the secondary pollution.Furthermore,innovative cooperation relationship should be built between water services companied,coal-fired power plants,power grid enterprises and government sectors,to ensure the technical and economic performances of the projects.

    Research on heat transfer of gas-solid two-phase flow in CFB boilers
    TAN Xuemei, LIU Shijie, ZHAO Bing, GONG Taiyi, WANG Jialin, HU Nan
    2021, 43(10):  61-67.  doi:10.3969/j.issn.1674-1951.2021.10.007
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    The particle size distribution of bed materials in circulating fluidized bed (CFB) boilers is wide.Gas-solid flow,a kind of multi-fluid composite flows,is of a complicated heat-transfer process.The common heat transfer mechanism of the two-phase flow in different states is analyzed,and its influencing factors,mechanism models and numerical simulation are investigated.The calculation methods for the heat transfer mechanisms of three gas-solid two-phase flows are summarized:solid-phase flow heat transfer,gas-phase flow heat transfer and radiation heat transfer.The important influencing factors of heat transfer are air velocity,particle size,bed pressure and temperature.The particle movement characteristics and concentration distribution are crucial for the heat transfer in CFB boilers.The improvement of the current calculation model should focus on wide particle size distribution.Optimizing the heat transfer efficiency of gas-solid two-phase flow in CFB boilers can boost the energy utilization rate and facilitate the achievement of carbon peaking and carbon neutrality.

    Research progress of immersion phase-change cooling for data centers
    ZHAO Tiantian, WANG Luyuan, ZHANG Xingyu, SUN Rongfeng, XUAN Chengbo, GENG Wenguang, CHENG Xingxing, WANG Zhiqiang
    2021, 43(10):  68-72.  doi:10.3969/j.issn.1674-1951.2021.10.008
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    With the advancement of Internet and 5G technology, the rapid development of data base stations in various industries puts forward higher requirements on the heat dissipation of electronic devices with high heat flux. Immersion phase-change heat dissipation technology has become hot issue because of its high heat dissipation performance, being convenient for maintenance and low noise. Based on the research on the principle, cooling material selection, boiling heat transfer mechanism and sealing material selection of the immersion phase-change cooling technology, the development and research status of the technology applied in data centers are systematically explored. Finally, the development direction of high heat dissipation technologies for digital base stations is prospected.

    Research and Development
    Event-triggered mechanism with settling time for actuator failures
    HUANG Kunfeng, HONG Jiachun, WU Yushen, ZHU Houyao
    2021, 43(10):  73-79.  doi:10.3969/j.issn.1674-1951.2021.10.009
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    Unknown forms of actuator failures during the operation of industrial systems might lead to the instability or even crash of the control systems. For a class of uncertain nonlinear systems with actuator failures,an event-triggered adaptive compensation control with prescribed settling time consensus is proposed.A finite time neural network adaptive controller which introduces a nonlinear transformation function is designed,so as to ensure the tracking error converges to the predefined interval within a prescribed settling time. Meanwhile,based on the backstepping technology,an event-triggered compensation control strategy with prescribed settling time consensus is proposed. Under this strategy,the system can achieve rapid compensation for the event of failure and preset the finite convergence time. Finally,the simulation experiments validate that the proposed strategy is able to effectively save network bandwidth and ensure the global uniform bounded convergence of the system.

    Design,analysis and application of large temperature difference cooling systems
    WEI Ruhua, WANG Yifeng
    2021, 43(10):  80-85.  doi:10.3969/j.issn.1674-1951.2021.10.010
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    In the analysis on the key factors affecting energy consumption of large temperature difference cooling systems powered by distributed energy,the effects of large temperature difference cooling on the evaporating temperature,COP(Coefficient of Performance)and auxiliary terminal equipment of chillers are studied.According to the calculation results,with the expansion of the temperature difference between supply and return and the drop of supply water temperature in a large temperature difference cooling system,the evaporating temperature of the chiller will decrease and the chiller's energy consumption will increase,but the energy consumption of the chilled water pumps will fall significantly.The energy consumption reduction realized by the large temperature difference cooling system has to be calculated on the premise of ensuring the operation of the chillers and fan coil units.This normal operation can be realized by lowering the cooling supply temperature,increasing the number of coils and adding anti-freezing measures.There is an actual project installed 15 large temperature difference chillers with 130 MW cooling load.The 15 refrigeration devices include three sets of 8 600 kW centrifugal chillers in series with lithium bromide units, nine sets of 7 384 kW centrifugal chillers and three sets of 2 813 kW centrifugal chillers.Compared with the conventional refrigeration system (7/12 ℃),the energy saved annually by the large temperature difference refrigeration system (3/13 ℃) grows by about 1.75 GW·h.This analysis provides a reference for subsequent similar projects.

    Study on shape-stable phase-change heat-storage materials based on waste concrete
    XIONG Yaxuan, HU Ziliang, WANG Huixiang, YAO Chenhua, SONG Chaoyu, DING Yulong
    2021, 43(10):  86-91.  doi:10.3969/j.issn.1674-1951.2021.10.011
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    The collection and synthesis of the skeleton materials for thermal energy storage(TES) will pollute our environment.To achieve the goal of carbon peaking and carbon neutrality as soon as possible,consume large-scale municipal solid wastes and avoid serious waste concrete accumulation,we take waste concrete as the skeleton material to fabricate shape-stable phase-change heat-storage materials.The chemical compatibility of a shape-stable phase-change material was analyzed by X-Ray Diffraction(XRD).And the micro-structure,thermal conductivity and TES performance of the composite were characterized by Scanning Electron Microscopy(SEM),Differential Scanning Calorimeter(DSC)and Laser Flash Analysis(LFA).The experimental results show the shape-stable composite is of the best molding effect and decent chemical compatibility when its nitrate mass fraction is 50%.With this proportion,its latent heat is 31 kJ/kg,the heat storage density is 505.90 kJ/kg in the range of 100~400 ℃,and the thermal conductivity is 0.12 W/(m·K).It can be concluded that using waste concrete as the skeleton material for heat-storage composite is feasible.