Abstract:Focusing on the'two to one'gas steam combined cycle cogeneration unit of a certain gas-fired thermal power plant,investigating the uniformity of the flue gas flow field in the selective catalytic reduction(SCR)denitrification system of the waste heat boiler,and using computational fluid dynamics(CFD)methods,exploring the control effect of adding a guide plate group on the flue gas flow field.The results show that the guide plate group can guide the direction of flue gas flow,weaken local vortices,and significantly optimize the uniformity of the flue gas flow field.When no guide plate group is added to the key section upstream of the catalyst,the coefficient of non-uniformity(Cv)of flue gas velocity distribution is 30.35%,indicating the problem of local flow velocity being too high or too low.After adding a guide plate group and optimizing its angle,spacing,and arrangement position,the Cv of the section decreased to 14.62%,and the uniformity of the flow field is improved by over 50%.

Abstract:Based on the existing thermal physical parameters of rocks and soils,the shallow geothermal energy reserves and the area available for heating and cooling within the Qiannan Prefecture region are estimated,and the suitable areas for development and utilization are qualitatively evaluated.The results show that the total heat capacity of geothermal energy beneath 200 m on the surface of Qiannan Prefecture is 7.75×1015 kJ/℃.The total heat exchange power in summer is approximately 2.450 billion kW,and in winter it is approximately 2.780 billion kW.The area available for heating in winter is approximately 55.600 billion m2,and the area available for cooling in summer is approximately 35.000 billion m2.Among them,the urban basin of Huishui and the Dushan basaltic karst basin are typical areas for the development and utilization of ground heat source heat pump systems and groundwater heat source heat pump systems,and two characteristic development and utilization models can be established,further promoting the regionalized development and utilization of shallow geothermal energy in the karst area of Southwest China,and helping to achieve the regional'double carbon'goals.

Abstract:In response to the problem of high energy consumption and serious waste of exhaust heat in the ventilation of a comprehensive pipe gallery,taking the standard ventilation section of an underground comprehensive pipe gallery power room in Jining City as the research object,conducting on-site testing and analysing of the winter exhaust temperature characteristics,proposing a heat pump system based on the utilization of exhaust waste heat in the comprehensive pipe gallery,and exploring its heating performance.The results show that when the outdoor air temperature dropped to-11.2℃in winter,the exhaust temperature remained at 13.0℃,and the exhaust temperature increased by 24.2℃.Compared with conventional air source heat pumps,the exhaust waste heat utilization heat pump system has an average coefficient of performance(COP)increase of 26.7%during the heating season.When the additional power consumption of the ventilation fan is not considered,the power consumption can be reduced by as much as 21.1%.Even if the additional power consumption of the 1.0 kW ventilation fan is included,the power consumption can still be reduced by 13.0%.The energy-saving effect is significant,and it can effectively avoid the technical problems of conventional air source heat pumps such as frosting and heating capacity degradation at low temperatures.

Abstract:In response to the upgrading requirements for the secondary Ⅳ-class effluent of an industrial wastewater treatment plant,in order to meet the surface water Ⅳ-class standards of chemical oxygen demand(COD)≤30.00 mg/L and ammonia nitrogen≤1.50 mg/L,the'aerated biological filter+powdered activated carbon adsorption'process is adopted for enhanced treatment.The results show that the effluent COD is stabilized at 22.00～24.00 mg/L after the renovation,and ammonia nitrogen is lower than 1.00 mg/L under winter low-temperature conditions,both of which were superior to the target limits,achieving a balance between stable compliance and effective operation cost.

Abstract:Taking the condensing gas-fired boiler as the research object,through methods such as establishing thermodynamic models,the operating and emission characteristics of the gas-fired boiler under the hydrogen blending ratio ranging from 0 to 100%are studied.The results show that under the condition where the boiler's output heat load and theoretical combustion temperature remain unchanged,as the proportion of natural gas blending with hydrogen increases,the radiation heat exchange ratio in the furnace rises,the heat exchange capacity of the condenser significantly increases,and the overall thermal efficiency of the boiler based on lower calorific value increases from 102.08%to 103.55%,with an increase of approximately 1.3%.The overall thermal efficiency of the boiler based on higher calorific value increases from 93.24%to 89.14%,with a decrease of approximately 4.4%.The NOx emission volume decreases from 69 mg/m3 to 24 mg/m3,a reduction of approximately 65.22%.The volume fraction of CO2 decreases from 8.90%to 0.

Abstract:A method for dynamic aggregation and regulation management of large-scale resources in a virtual power plant(VPP)is proposed.By determining the peak periods,off-peak periods,and normal periods of regional electricity consumption,the power system load demand data,flexible load characteristic data,and price data for each period are obtained.The operation objective function of VPP under the market mechanism is proposed,and its participation in the market operation mechanism is established.The types of flexible resources are identified,and a multi-flexible resource dynamic aggregation model of VPP is constructed.The improved wolf pack algorithm(WPA)is used to optimize the satisfaction factor of the satisfactory decision.The results show that compared with traditional methods,the improved WPA algorithm can significantly reduce costs,enabling VPP to meet electricity demand through gas turbines and energy storage equipment during peak periods,thereby enhancing the flexibility and economy of the power system.

Abstract:The rotary kiln is the core equipment in the production of asphalt coke.Its combustion process integrates multiple physical fields such as flow,heat transfer,mass transfer and the rotational motion of materials,as well as chemical reactions,and is a typical complex coupled process.Considering the influence of physical and chemical reactions on the heat transfer process inside the kiln,for a rotary kiln with a length of 55 m,a one-dimensional axial comprehensive heat transfer mathematical model is established to analyze the heat transfer law under the reverse flow of gas and materials inside the kiln.A material volatilization analysis model and a material layer heat transfer model are constructed,and the volatilization rate curve and the temperature distribution curve of the material layer are obtained through calculation.The results show that the volatilization rate is the highest at approximately 15 m from the kiln tail,and the temperature of the material layer reaches the highest at approximately 38 m.

Abstract:In response to the severe hydraulic imbalance and high electricity consumption of the centralized heating system in a certain residential area of Tianjin City,a simulation model is established using the Viheating hydraulic calculation software to compare and analyze the operating characteristics of the jet pump system and the original balance valve system.The results show that the jet pump system can reduce the frequency of the circulating pump to 26.00 Hz,decrease the flow by approximately 50%,reduce the head by approximately 59%,and lower the power of the circulating pump from 25.07 kW to 7.36 kW.During the heating season,it can save 64 250 kWh of electricity and the investment recovery period is 6.16 a.The jet pump technology can effectively solve the problem of hydraulic imbalance in the secondary network,achieve the goal of energy-saving and emission reduction,and has good economic and social benefits.

Abstract:Based on the remote sensing image data of land use in the Chengdu-Chongqing urban agglomeration from 2000 to 2020 for five periods,the urban form is quantified.The spatial econometric model is used to analyze the impact of urban form on carbon emissions.The results show that from 2000 to 2020,the carbon emission volume of the Chengdu-Chongqing urban agglomeration increased from 154.72 Mt in 2000 to 439.28 Mt in 2020.Spatially,it presented a bipolar pattern with Chengdu and Chongqing as the core.There is a significant correlation between urban form and carbon emissions.For every 1%increase in the area of urban patches and the maximum patch index,the total carbon emissions in the region will increase by 2.642%and 4.600%,respectively.For every 1%increase in the percentage of similar adjacent areas,the total carbon emissions will decrease by 7.600%.

Abstract:Taking residential buildings in Shandong Province as the research object,exploring their spatiotemporal evolution as well as future development trends.Based on the calculation of carbon emissions from residential buildings in Shandong Province from 2000 to 2021,the spatiotemporal evolution characteristics of carbon emissions from residential buildings at the municipal and county levels in Shandong Province are analyzed using night-time light inversion.Feature selection is conducted using Pearson-RF,and the STIRPAT model and scenario analysis are employed to predict the carbon emissions from residential buildings in Shandong Province.The results show that the carbon emissions from residential buildings in Shandong Province are continuously increasing,with regional differences and spatial correlations existing within the system.Only under the low-carbon scenario,carbon peak(peak of 14 151.43 million t)can be achieved in 2030.It is recommended to achieve the emission reduction targets by measures such as controlling building scale,promoting green renovations,and formulating differentiated regional policies.

Abstract:For the optimization of operating parameters of the top-floor radiation cooling coupled with fresh air supply system,a multi-objective optimization and decision-making method is proposed.The non-dominated sorting genetic algorithm(NSGA-Ⅱ)is applied,with system energy consumption and the expected dissatisfaction percentage(PPD)as the objective functions for optimization.Pareto optimal solution sets under different personnel numbers are generated,and the entropy weight-approaching ideal solution sorting(EW-TOPSIS)decision-making model is introduced to objectively determine the global optimal configuration.The results show that in the low-load condition with 3 people and the high-load condition with 7 people,energy consumption is the dominant factor in decision-making,with weights of 0.70 and 0.76,respectively.While in the medium-load condition with 5 people,the importance of thermal comfort increases,with a weight of 0.32.After optimization,the system tends to adopt a higher supply water temperature and a lower supply water flow rate,and adjusts the supply air temperature and supply air volume to cope with different load changes,providing a reference for the energy-saving and comfortable operation of the radiation air conditioning system in variable working conditions.

Abstract:To explore the influence of the selection of mixed working fluids on the performance of the cascade heat pump system,the working principle of the cascade heat pump is systematically elaborated,and the screening process of mixed working fluids is described.The model of the cascade heat pump is designed and simulated using Matlab,and the REFPROP software is called to analyze the effects of factors such as condensation and evaporation pressures,compressor power consumption,mass fraction,and intermediate condensation temperature of different mixed working fluids on the energy efficiency ratio(COP).The results show that the application of 3 types of mixed working fluids increases the condensation pressure by 8.60%to 25.40%and the evaporation pressure by 8.70%to 26.23%.When the mass fraction of R134a is 10%,the compressor power consumption of the R134a+R152a combination is lower,at 24.26 kW.Compared with the other 3 groups of working fluids,the COP of the R152a+R1234ze combination is higher,reaching 3.27.For the cascade heat pump system,different mixed working fluids have specific optimal intermediate condensation temperatures,and the R152a+R1234ze combination has the lowest power consumption of 48.28 kW.As a low-temperature-level mixed working fluid,R152a+R1234ze always maintains the maximum COP when the low-temperature evaporation temperature and high-temperature condensation temperature change.

Abstract:In response to the problems of complex coupling of operating parameters in central air conditioning refrigeration systems,strong reliance on traditional manual parameter adjustment experience,and the tendency of single intelligent algorithms to fall into local optima,resulting in poor energy efficiency optimization effects,a new energy-saving optimization method based on multiple genetic algorithms(MGA)is proposed.Through grey correlation analysis(GRA),three key influencing parameters,namely the outlet water temperature of the main unit,the frequency of the chilled water pump,and the frequency of the cooling water pump,are selected from 10 parameters.The backpropagation(BP)neural network is used to construct an energy efficiency ratio(EER)prediction model with a prediction error of less than 0.4%as the fitness function.The parameter association rules mined by the association rule algorithm(Apriori)are introduced as constraints.The MGA is used for global optimization.The results show that under a load rate of 80%to 90%in a commercial building,the method increases the system energy efficiency ratio by an average of 5.75%and up to 7.93%,effectively improving the system operation efficiency.

Abstract:An abnormal vibration occurred in the drain pipe of the high-pressure heater of a thermal power station,causing severe erosion of the pipe.Particularly at the bends,it affected the safe and stable operation of the unit.By investigating the causes of the abnormal vibration of the drain pipe of the high-pressure heater in this thermal power station,and conducting calculation and analysis using the pipeline stress analysis software CAESAR Ⅱ,the main cause of the abnormal vibration of the pipe is determined,and improvement measures are proposed.It is found that the design defect of the pipe support led to insufficient stiffness,and the pulsation excitation generated by the gas-liquid two-phase flow coupled with the third-order mode frequency of the piping system is the main cause of the vibration.By adjusting the layout of the pipe support and improving the rigidity of the pipe,the third-order mode frequency of the pipe can be increased,effectively solving the vibration problem of the drain pipe.Optimizing the layout of the pipe support can effectively solve the vibration problem,providing a reference for the design of high-pressure heater drain pipes in new power plants.

Abstract:To study the carbon emissions of the external insulation walls of prefabricated residential buildings in cold regions,based on the full life cycle theory,the full life cycle of prefabricated concrete insulation exterior walls is divided into five stages:production,distribution,construction,operation and demolition.A carbon emission calculation model for the full life cycle of prefabricated concrete insulation exterior walls is established,and the carbon emission factor method is used to calculate its full life cycle carbon emissions.The results show that the carbon emissions from the production stage account for 90.28%of the total carbon emissions,while those from other stages together account for 9.72%.The production stage makes a significant contribution to the carbon emissions throughout the entire life cycle.Putting forward suggestions on energy-saving and emission reduction methods in the production stage is conducive to the transformation of the production of prefabricated concrete insulation exterior wall components in cold regions,achieving energy-saving and emission reduction in the construction industry,and contributing to the realization of the'double carbon'goals.

Abstract:To improve the prediction accuracy of the energy storage frequency regulation instructions for wind farms,the global curvature-stability analysis method is adopted to calculate the non-linear degree(curvature scaling factor)S1 of the deviation from the linear trend of the original wind speed sequence and the stability(change suppression index)S2 of the sequence value changes.The update gate parameters of the gated recurrent unit(GRU)are dynamically adjusted using the non-linear degree S1 and stability S2,and the original wind speed sequence is placed in the improved GRU network for prediction,obtaining the final prediction result.The results show that in terms of prediction error,the method proposed in this study reduces the MAE of the GRU network by an average of 83.34%,the SSE by an average of 98.24%,the RMSE by an average of 74.21%,and the MAPE by an average of 86.10%compared to the GRU network.

Abstract:Taking the sintering desulfurization and denitrification project of a certain steel enterprise as the research object,based on the actual operation data of the existing activated carbon process,the energy consumption index and carbon emissions are systematically analyzed,and the energy-saving and carbon reduction potential of the circulating fluidized bed(CFB)desulfurization+selective catalytic reduction(SCR)denitrification process is compared and predicted.The results show that compared with the existing activated carbon desulfurization and denitrification process,the energy consumption index can be decreased by approximately 48.9%,with an annual reduction of 19 320 tons of standard coal in energy consumption and a 43.4%decrease in carbon emissions,resulting in an annual reduction of 122 640 t of carbon emissions.

Abstract:To investigate the energy utilization status of liquefied natural gas(LNG)receiving stations,taking a large domestic LNG receiving station as the research object,a method combining on-site testing and data analysis is adopted to calculate the efficiency and conduct economic evaluations of the low-pressure pumps,high-pressure pumps,BOG compressors and seawater pumps of this receiving station.Specific optimization measures are proposed in terms of equipment maintenance management,intelligent control,operation processes and equipment renovation.The results showed that the low-pressure pump and high-pressure pump units are not economically operated by 57.1%and 33.3%,respectively.The seawater pump unit is not economically operated at all.The BOG compressor operated reasonably.Through measures such as optimizing unit operation,strengthening equipment maintenance,and implementing frequency conversion renovations,annual electricity costs are saved and CO2 emissions are reduced.

Abstract:Accurately predicting the process parameters of oil receiving and dispatching in the crude oil depot and selecting the appropriate heating process scheme is of great significance for reducing the energy consumption of oil depot operation and improving operational efficiency.Based on the principles of heat transfer and fluid mechanics,a steady-state simulation model including components such as pipelines,heating furnaces,and storage tanks is constructed.The solution is obtained by using the node-component association matrix method and the Broyden iterative algorithm,and by utilizing the self-developed large-scale crude oil depot process simulation software.Establish a total energy consumption calculation model,analyze the energy consumption of the two heating processes,'furnace first then tank'and'tank first then furnace',under different environmental temperatures and storage periods,and propose a heating process selection strategy based on environmental temperature and storage period.The results show that,verified through a case of an oil depot in the north,the relative deviations of the model's predictions for pressure and temperature are respectively lower than 5.96%and 3.92%.When the environmental temperature is-25℃and the storage period is 10 d,the'tank first then furnace'process can save 26.80%of energy.

Abstract:For the organic waste liquid and waste gas generated by a certain enterprise,a thermal insulation incineration disposal scheme is proposed.The mixed low calorific heat of the waste liquid and waste gas is calculated using the element mixture analysis method.The detailed structural design of the vertical thermal insulation incinerator is completed,and the actual operation adjustment of the incinerator is carried out based on the temperature rise curve combined with the staged air distribution technology.The results show that the mixed fuel can achieve self-sustaining combustion at around 1 100℃,with the flue gas temperature remaining stable at 1 100℃to 1 200℃,and the pollutants are discharged in compliance with standards.