Abstract:A short-term photovoltaic power generation prediction model based on adaptive noise complete ensemble empirical mode decomposition-long short-term memory network-sparrow search algorithm(ICEEMDAN-LSTM-SSA)is proposed.Taking a certain photovoltaic power station in Bohu County,Baotou City,Xinjiang as the research object,the influence of different climate conditions on the prediction accuracy is analyzed.The research shows that using the ICEEMDAN decomposition algorithm to preprocess the power generation sequence can effectively improve the prediction accuracy of the LSTM model for photovoltaic power generation,the ICEEMDAN-LSTM-SSA prediction model demonstrates obvious universality under different climate conditions,and the prediction results are more accurate.

Abstract:To reduce the high energy consumption of air conditioning systems in rail transit vehicles and achieve precise testing and standardized evaluation,taking the trains of Chongqing City metro line 6 as the object,a combination of numerical calculation and experimental testing is adopted to compare the energy consumption testing and calculation methods of air conditioning systems in rail transit vehicles,such as orthogonal experiment method,typical sky method and weight method,and to provide the applicable scenarios of each method.The results show that the orthogonal experiment method,the typical sky method and the weight method can all obtain highly accurate energy consumption of the air conditioning system of rail transit vehicles.The orthogonal experimental method has high accuracy and can establish the energy consumption prediction relationship.The typical sky method is applicable to the simulation calculation of energy consumption of air conditioning systems in rail transit vehicles.The working conditions of the weighting method are uniform and stable,and it is easy to implement in the laboratory.

Abstract:Increasing the reheating times of the unit and adopting higher steam parameters are effective methods to improve the energy utilization efficiency of coal-fired power plants.Through the research on the different main steam and reheat steam parameters adopted in the Kemen Phase Ⅲ project,the economic comparison of different main steam and reheat steam parameter improvement schemes is conducted.The economic changes of the project after the improvement of main steam and reheat steam parameters under different coal prices and utilization hours are obtained,and suggestions are provided for the parameter selection of subsequent secondary reheat units.The results show that through technical and economic comparison,the appropriate main steam parameters for the Kemen Phase Ⅲ project are as follows,main steam pressure of 32 MPa,main steam temperature of 600℃,primary reheating temperature of 623℃,and secondary reheating temperature of 620℃.The lower the coal price,the lower the utilization hours,and the longer the static payback period for the improvement of main steam parameters.For projects with high coal prices and high utilization hours,improving the main steam parameters is more beneficial to the project's economic efficiency.

Abstract:To address the issue of uniformity in velocity and temperature fields in high-space cold storage,a combination of numerical simulation and experimental verification is adopted to study the air flow organization characteristics of high-space cold storage under four different supply and return air modes,air distribution duct supply air and natural return air,vertical orifice plate return air through ordinary air supply,natural return air through unpowered air supply,and natural return air through low pressure difference air supply.The results show that under non-steady-state conditions,the absolute error between the test results of the average temperature at the measurement points in the warehouse and the simulation results is less than 0.2℃,verifying the reliability of the theoretical model.Under steady-state conditions,the velocity non-uniformity coefficients in the warehouse of the four different supply and return air methods in numerical simulation are 0.85,1.11,1.07 and 1.09,respectively.The air distribution duct supply air and natural return air method improves the uniformity of the velocity field by more than 15%compared with other supply methods.The temperature non-uniformity coefficients inside the warehouse under four different supply and return air methods are 0.76,0.63,0.18 and 0.59,respectively.The temperature uniformity of the natural return air without powered supply air is more than 60%higher than that of other supply air methods.Considering the temperature uniformity requirements for goods storage in cold storage,for high-space logistics cold storage,it is recommended to adopt the supply and return air method in sequence,unpowered supply air and natural return air,low-pressure difference supply air and natural return air,air distribution duct supply air and natural return air,and ordinary supply air and vertical orifice plate return air.

Abstract:Aiming at the energy loss problem of the power plant boiler system,an energy-saving design scheme based on the stepwise utilization of energy is proposed.A technical path for the stepwise recovery of flue gas waste heat,multi-level optimization of feed water heating,staged utilization of steam extraction and dynamic regulation of system heat flow is constructed,and operation tests are carried out in a 350 MW unit.The results show that the coal consumption per unit of power generation has decreased from 322.47 g/kWh to 284.36 g/kWh,the thermal efficiency of the boiler has increased from 86.23%to 93.89%,and the flue gas temperature has decreased from 167.62℃to 142.71℃.The load fluctuation range has decreased from 6.47%to 3.26%,and the feed water temperature deviation has decreased from 8.26℃to 5.48℃.The operational stability has been significantly enhanced.The CO2 emission intensity has decreased from 0.942 kg/kWh to 0.843 kg/kWh,with an investment payback period of approximately 1.5 a to 2.0 a,demonstrating good economic and environmental benefits.

Abstract:In light of the unique climatic characteristics of the region and the design requirements of rural affordable housing,building information modeling(BIM)technology is adopted to construct a model,and green building analysis software is utilized to simulate and analyze key performance indicators such as indoor and outdoor sunlight,ventilation,lighting,and thermal environment,thereby optimizing the design scheme.The results show that the introduction of BIM technology can provide a reference for the optimization of the scheme in the early design stage,effectively reduce energy consumption and improve the performance of the thermal environment.BIM technology is an important means to achieve the green,low-carbon and energy-saving economic goals of rural affordable housing in hot summer and warm winter regions,and it is of great significance for improving the quality of rural green building design.

Abstract:Four typical metro stations in hot summer and warm winter areas are selected,and high-precision micro-differential pressure sensors are used to continuously collect the infiltration wind pressure on both sides of the platform screen doors during the operation period.Taking the second pressure extreme value during the station entry process as the benchmark,the effective data segment is intercepted to establish a dynamic time axis calibration to eliminate the train arrival dispersion,eliminate the sudden acceleration change,and introduce a bimodal Gaussian function to fit the pressure waveforms at the station entry and exit,thereby achieving the quantitative representation of the wind pressure of the platform screen door penetration.The results show that the track area of the train entering the station is higher than the platform level,forming a positive pressure peak,while leaving the station forms a negative pressure trough.The platform screen door at the rear of the train has a larger peak when the train enters the station and a smaller trough when it leaves.The pressure difference increase between adjacent gates in the non-peak area is 0 Pa to 5 Pa,and in the peak area it is 5 Pa to 25 Pa.The gradient statistics are obvious.During peak hours,the intervals between trains are compressed,and the disturbance of the following vehicles causes the pressure difference at the station to increase,but the difference is limited.When leaving the station,due to insufficient negative pressure recovery,the suction force weakens,and the absolute value of the pressure difference drops by 50%.The volume and type of the station are the key factors influencing the pressure difference fluctuation of the exhaust system.In a standard station with relatively small space,the pressure difference fluctuation range is reduced by 30.05%.

Abstract:Based on the elliptical deep pit tube and combined with the theory of self-excited oscillation pulse flow enhanced heat transfer,a new type of self-excited pulse type pit heat transfer tube is proposed.The study uses numerical simulation methods to compare and analyze three-dimensional models of light tubes,concave pit tubes,and a new type of self-excited oscillating pulse concave pit heat transfer tube.By observing the velocity and temperature fields inside the new heat transfer tube,the enhanced heat transfer mechanism is analyzed.The results showed that when the parameters of the self-excited oscillation cavity are d1=15 mm,D=120 mm,L=42 mm,and the inlet flow velocity is 1.5 m/s,the comprehensive evaluation coefficient(PEC)of the new heat exchange tube increased by about 21.1%compared to the light tube and about 2.7%compared to the concave pit tube.Compared with the concave pit tube,the velocity of the central jet in the new heat exchange tube is faster and more evenly distributed,the overall temperature is higher,and the rate of temperature rise along the flow direction is also faster.This heat transfer tube generates multi-scale vortices through a unique structural design,utilizing vortex excitation phenomena to stimulate the synergistic effect of vortices and pulsating flows,achieving composite enhanced heat transfer and providing innovative ideas for optimizing the performance of heat transfer equipment.

Abstract:To explore the influence of surface roughness on the performance of wind turbine blades,a rectangular protrusion is used instead of the actual rough band to numerically simulate the aerodynamic performance of two airfoil types,DU93-W-210 and DU97-W-300,to determine the roughness sensitive position of this airfoil.On this basis,the protrusion size is changed.Analyze the specific degree of damage caused by the size of the rough zone to the aerodynamic performance of the wind turbine airfoil.The results show that surface contamination can seriously damage the aerodynamic performance of wind turbine blades.Moreover,as the relative thickness increases,the influence of roughness on the aerodynamic performance of the airfoil becomes more severe.However,the relative thickness does not change the roughness sensitive position of the airfoil.The roughness sensitive position of the DU series airfoil is at 1%c from the leading edge.The size of the boss also affects the aerodynamic performance of the airfoil,and the change in boss height has a greater impact on the performance of the airfoil than the boss width.By analyzing the influence of roughness on the airfoil of wind turbine blades,the operating status of the blades can be accurately identified,and the operating conditions of the blades can be inferred,providing a reference for the safe and stable operation of wind turbines.

Abstract:The roof of a building plays a significant role in energy-saving and emission reduction in construction due to its high peak heat gain and large roof area.The influence of factors such as the dimensions of ventilation outlets,air inlets and air outlets,cavity wind speed,solar panels and wind deflector plates on the thermal performance of the ventilated roof is analyzed through the heat fluid-radiation coupling simulation method.The results show that the ventilation roof structure equipped with ventilation openings and air deflector plates has better thermal performance.The energy-saving effect is better when the air inlet wind speed is within 1.0 m/s to 1.5 m/s.The increase in the size of the air inlet and outlet causes the thermal performance of the ventilated roof to first improve and then decrease.The larger the area of the solar panels,the greater the energy savings of the ventilated roof.

Abstract:The additional solar room is a passive energy-saving method that sets up a closed glass space on the south side of a residence to utilize solar energy.It has the characteristics of reducing heating energy consumption in winter,improving the indoor thermal environment,simple structure and low cost,and is widely used in rural houses in cold regions.Based on relevant domestic and international research,analyzing the application of solar rooms in energy-saving renovations of rural houses.It summarizes the research progress in recent years from aspects such as thermal performance optimization,application of new materials,space design and comfort improvement,and points out that there are still deficiencies in summer overheating control,economic feasibility and user feedback.

Abstract:Under the background of low-altitude economy and green transformation,focusing on the optimization path of carbon footprint models in the field of unmanned aerial vehicle mapping.In response to the problems of high energy consumption and high emissions in traditional mapping,combined with the full life cycle assessment(LCA)and sensitivity analysis of unmanned aerial vehicle mapping,it extracts policy factors of low-altitude economy and proposes a multi-dimensional optimization path for unmanned aerial vehicle mapping to construct a dynamic carbon footprint accounting framework.The results show that under the same conditions,the carbon footprint mapped by unmanned aerial vehicles is directly proportional to the carbon intensity coefficients of raw materials,transportation vehicles and electricity,and inversely proportional to the policy factor of low-altitude economy.

Abstract:To explore the applicability of different machine learning algorithms in the performance prediction of deep well ground source heat pumps with enhanced heat transfer using nano-fluids as circulating fluids,the operation data of the heat pump system using 2%Al2O3 nano-fluids are monitored and collected in real time,and then a database is constructed.And calculation and analysis are carried out respectively by using algorithms such as support vector machine(SVM),particle swarm optimization-support vector machine(PSO-SVM),and extreme gradient boost(XGBoost).The results show that the XGBoost algorithm has excellent predictive performance.Its prediction of system coefficient of performance(COP)and heat supply(Q)has a fitting degree of 100%within an error range of±5%.This result fully demonstrates that the algorithm has high fitting accuracy and no obvious overfitting phenomenon occurs.

Abstract:To clarify the air conditioning system solution suitable for ultra-low energy consumption buildings in hot summer and cold winter regions,based on EnergyPlus simulation,a certain ultra-low energy consumption office building in Shanghai is taken as the research object to comparatively analyze the operational energy consumption and carbon emission characteristics of multi-split systems,centrifugal chiller+gas boiler and air-cooled heat pump systems.The results show that the energy consumption per unit air conditioning area of each system is 22.47～29.00 kWh/(m2·a),and the air conditioning system accounts for 41.0%～47.2%of the total energy consumption of the building.The total energy consumption of multi-split systems is relatively low and the indirect carbon emissions are less.The proportion of carbon emissions from refrigerant leakage will rise from 33.8%to 46.0%as the carbon factor of the power grid decreases.

Abstract:Ten motor vehicles covering different types,emission standards,driving ranges and fuel types are selected as test samples.Urban roads are divided into three functional zones,core commercial areas,industrial areas and residential areas,and test routes are planned.The exhaust gas is collected by condensation drying method,and the volatile organic compounds(VOCs)samples are extracted by solid-phase microextraction technology for analysis.Targeted traffic control and urban air quality management plans are formulated.The results show that the concentration of VOCs emissions increases significantly in the core commercial area,while it decreases successively in the industrial area and the residential area.Freight vehicles are the main contributor to VOCs emissions,among which trucks have a relatively large contribution rate under medium-speed operating conditions.When the traffic volume reaches 900 vehicles per hour,the VOCs emission concentration in the core commercial area is the highest,reaching 7.8 μg/cm3.Under low-speed,medium-speed and high-speed operating conditions,the contribution rates of VOCs emissions from freight vehicles are 40%,32%and 25%,respectively.

Abstract:Taking a large exhibition hall park as the research object,a smart energy management system architecture based on internet of things(IoT)and digital twin technology is proposed.By automating the transformation of existing equipment,building a smart energy management platform,and establishing a smart command center,a full-chain closed-loop management of energy data is achieved.The results show that the system reduces the energy consumption of the water pump by 23.1%,shortens the fault response time by 81.0%,and saves over 1.5 million yuan in operation and maintenance costs annually,providing a reference for the digital and low-carbon transformation of the park.

Abstract:In response to the security issues of the power system caused by the large-scale integration of distributed photovoltaic power into the distribution network containing multiple main resources,analyzing the impact degree of the complex planning of distributed photovoltaic power,acquiring the configuration planning of distributed photovoltaic power,and identifying key challenges such as the complexity of distribution network planning,the expansion of power quality fluctuations,and the narrowing of relay protection range.Propose a site selection and capacity determination method following the principle of'local,nearby and networked',a grid connection parameter configuration strategy enabling Volt/VAR control,construct a key performance indicator(KPI)system including voltage over-limit rate and line loss rate,and design a closed-loop implementation process of'analysis-simulation-implementation-evaluation'.Research shows that reasonable planning can reduce line losses by 5%to 12%,effectively enhance local consumption capacity.

Abstract:Based on the internally reversible Rallis cycle model,the performance characteristics of it under the effective power(Ep)target are studied,and the analytical formula of Ep is derived.The isothermal process expansion ratio(σ)is taken as the optimization variable to analyze the influences of compression ratio(ε),pressurization ratio(λ),pre-expansion ratio(ρ),and heat transfer loss(B)on the cycle performance.And compare the performance differences of the cycle under the Ep and power(P)targets.The results showed that the cyclic relationship curve between Ep and σ presents a parabolic shape,σ is the best value(σEp)make cycle Ep to achieve the maximum(Ep)max.The relationship curve between the cyclic Ep and efficiency(η)presents a twisted leaf shape that returns to the origin.When ε,λ and ρ increase while B decreases,(Ep)max and its corresponding efficiency(ηEp)increase.When other conditions are constant,the η corresponding to the maximum Ep of the cycle is greater than that corresponding to the maximum P.When Ep is selected as the objective function,the loop can achieve an efficiency improvement at the expense of less power.

Abstract:To promote the low-carbon transformation of road engineering,based on the data of expansion and renovation projects,the carbon energy calculation method is adopted to quantify the carbon emissions and energy consumption in the production,transportation and mixing stages of asphalt pavement recycled aggregate(RAP),and to evaluate the carbon emission benefits and energy consumption benefits at each stage.The results show that the carbon dioxide emissions during the RAP production process are only 2.312 kg/t,which is 84.1%lower than that of natural aggregates.Application of RAP reduced the carbon emissions and energy consumption of ATB-25 mixture by 3.435 kg/t and 1.557 38 kg/t,respectively,and the plant-mixed cold recycled mixture by 8.771 kg/t and 3.949 06 kg/t,respectively.Research shows that RAP technology has obvious advantages in energy-saving and emission reduction and can provide a reference for the construction of green transportation.

Abstract:Based on the operating characteristics of the power-distributed system,the Pipe Flow Expert professional simulation software is used to construct a refined model,and the comprehensive performance differences between the power-distributed system and the traditional power-centralized system are systematically compared and studied from the aspects of energy consumption and hydraulic characteristics.The results show that the power-distributed system reduces the total energy consumption of the water pumps by 40.8%by replacing the balance valve with distributed water pumps in each branch,and the energy-saving effect is obvious.However,due to the enhanced coupling degree between branches,when some branches are shut down,the flow offset coefficient of the remaining branches reaches 1.15,which is higher than 1.12 of the traditional system.The system stability and anti-interference ability are relatively weak.