Supply Mode Research Articles

The airflow distribution and aerosol diffusion rules in the negative pressure isolation ward

Negative pressure wards are significant in preventing the spread of infectious pathogens which play a crucial role in fighting against COVID-19. Owing to the negative pressure, contaminated air with pathogens is not able to flow from the wards to non-contaminated zones while fresh filtered air will be transported to the ward via the ventilation system. As airflow controlled by ventilation systems affects the motion of pathogens, for example, infectious aerosol particles, the ability of a negative pressure ward to reduce the risk of infection highly relies on an effective ventilation system. In this investigation, impacts of airflow patterns under various human postures and ventilation processes aerosols diffusion are analyzed via the computational fluid dynamics (CFD) simulation. According to the results, among three airflow patterns, the highest contaminant removal efficiency is 57% at 200 s with the top supply and bottom return mode; besides, in three postures, in the case that the patient is in a standing position, the contaminant removal efficiency is the highest. Furthermore, it is found that the best airflow scheme is a slit tuyere in the ward, with a top supply and side return mode and a sitting position for the patient. This study may provide a reference for the design of airflow in negative pressure isolation wards, control of contaminants, and prevention of viral infections, so as to ensure a good working and recovery environment for medical staff and patients.

Design of triple cogeneration system for hydrogen fuel cell in greenhouse based on resource analysis

Introduction: Hydrogen energy has a massive advantage in the energy supply mode regarding greenhouse gas emissions. Nevertheless, the energy supply system needs to be redesigned to meet the heating/cooling needs and the goals of using hydrogen energy.Methods: The comprehensive utilization efficiency of system energy can be improved using resource analysis to solve the problem of waste heat and formulate a technical plan for triple cogeneration of hydrogen greenhouse.Results: By calculation, the energy efficiency of the coal boiler heating system, the hydrogen energy heating system and the hydrogen greenhouse triple heating system are 65%, 52.93%, and 73.36%, respectively. Compared to the coal boiler heating system and the hydrogen energy heating system, the advantages of the hydrogen greenhouse triple cogeneration system are that the comprehensive utilization efficiency of the system energy has been improved, and no CO2 is generated when it works, which does not cause pressure on environmental protection. At the same time, the exergy efficiency of the hydrogen greenhouse triple cogeneration system is higher. Currently, due to the high price of hydrogen and fuel cells, the economic advantages are not outstanding. Still, coal energy is expected to be replaced in the future with the continuous decline in the cost of hydrogen and fuel cells. According to the current coal price, when the hydrogen price decreases to below $1.3/kg, coal will lose its price advantage in terms of fuel. At the same time, hydrogen has a high energy density, small volume, and low transportation cost. According to IRENA and Hydrogen Council, the cost of producing hydrogen from renewable energy will drop to $1/kg by 2050. The system will significantly reduce the operating costs of greenhouses in the future.Discussion: As a result, the hydrogen greenhouse triple cogeneration system is suitable for producing greenhouse agriculture and the heating method of fossil fuel combustion that will replace coal in the future.

An experimental study of various load control strategies for an ammonia/hydrogen dual-fuel engine with the Miller cycle

Hydrogen and ammonia, as two renewable carbon-free combustibles, are considered to be potentially excellent alternative fuels for internal combustion engines. Since hydrogen and ammonia have opposite and complementary combustion characteristics, the co-combustion of ammonia with hydrogen is reasonable. However, there are few detailed experimental studies of load control strategies for an ammonia‑hydrogen engine. In this study, four load control strategies including the variation of ammonia volume share (AVS), qualitative control, quantitative control, and adjustment of intake variable valve timing (VVT) are proposed and assessed for their applicability in an ammonia/hydrogen dual-fuel engine. The ignition and combustion characteristics of ammonia do not allow for high thermal efficiency, so the Miller cycle is introduced to improve engine performance. The engine employs fuel supply modes of ammonia port injection and hydrogen direct injection at 1500 rpm. In general, the engine achieves higher brake mean effective pressure (BMEP) and brake thermal efficiency (BTE) at different AVS. Moreover, qualitative control and adjustment of intake VVT allow the engine to own a wide regulation range of BMEP and maintain the BTE of more than 37% under most conditions. However, quantitative control appears to be an inadequate strategy for the engine due to the lower BMEP and BTE.

Global energy and leakage optimization in water distribution systems from water treatment plants to customer taps

Delivering drinking water from water treatment plants (WTPs) to customer taps results in significant energy consumption and water loss due to leakage. The energy consumption involved in this process includes both the energy used in the water distribution networks (WDNs) and buildings. Existing research primarily focuses on optimizing energy consumption in WDNs while ignoring the energy consumption at buildings. Building height and water supply mode are crucial factors that impact energy consumption. A building hydraulic model involving various supply modes coupled with the WDN hydraulic model is developed to calculate the energy consumption and leakage from WTPs to taps. An optimization model is then proposed to minimize expenses by placing regional pump stations (RPSs) and scheduling pumps in WTPs. The application of the proposed method to a realistic WDN resulted in a 1.17% decrease in energy consumption and a 6.98% reduction in water leakage compared to traditional methods.

Carbon-neutral power system transition pathways for coal-dominant and renewable Resource-abundant regions: Inner Mongolia as a case study

Under the vision of carbon neutrality, reaching carbon peaking and neutrality targets in the power industry in coal-dominated, renewable energy-rich provinces is facing unprecedented development pressure. This study used the optimization model to research the deeper decarburisation path with the lowest cost to the Inner Mongolian power industry. Then, three scenarios were set based on the gradual increase of carbon emission constraints and the increased renewable energy target. The electricity demand, installed capacity and generation, cost-effectiveness, and carbon emissions were evaluated under the three scenarios. Results showed that (1) electricity demand will grow steadily in all three scenarios by 2060, to achieve carbon peak and carbon neutrality targets, with industrial electricity demand falling by an average of 41.15%, while the ‘transport, storage & postal’ needs to rise by 88.82%. (2) Inner Mongolia needs to fully tap the renewable energy potential, establish a renewable energy storage system, diversify its power supply mode, and achieve the 2060 carbon neutrality target. (3) Achieving a profound emission reduction at minimum cost is feasible. Compared with keeping 13.01% of coal power as a flexible power supply in the nationally determined contributions scenario, completely withdrawing coal power in the carbon neutrality scenario in 2060 will reduce carbon emissions by 148.10 million metric tons and costs by 1375.92 billion yuan. This method can analyse the carbon emission pathways and emission reduction measures of the resource-based provincial power sector, including setting boundaries, scenario analysis, forecasting future emissions, analysing results, and providing policy recommendations. Providing relevant countermeasures for government departments, industry organisations, power companies, and individuals to conduct carbon neutrality-related work.

Study on the operation strategies and carbon emission of heating systems in the context of building energy conservation

AbstractCoal‐fired thermal power must be flexible to enable the grid absorption of inconsistent photovoltaic (PV) and wind power. Combined heat and power (CHP) coal‐fired plants are the primary source for district heating systems. This paper uses a 330 MW subcritical CHP unit as an example to carry out the study. With the promotion of building energy efficiency, when the thermal index is reduced to below 20 W/m2, the low‐load operation of CHP can meet the wind power and PV feed‐in demand and guarantee residential heating without the need for flexibility modification. Meanwhile, more renewable energy generation can reduce carbon emissions from the power supply, further contributing to reducing carbon emissions from buildings. The impacts of different envelope parameters and supplementary heat sources on building carbon emissions are also studied. The conclusion shows that the degree of their impact on carbon emissions ranks as ESMs (energy supply modes) > Factor D (infiltration N50) > Factor A (external wall heat transfer coefficient) > Factor C (window heat transfer coefficient) > Factor B (roof heat transfer coefficient). When the building's heating energy consumption gradually decreases, the distributed heat pump unit can replace the coal‐fired boiler to supply the peak heat load demand. In the future, China's district heating systems can be gradually changed from the current CHP and coal‐fired boilers to CHP and distributed heat pumps.

Impact of different supply modes of stratum ventilation on airflow and contaminant distribution characteristics

For non-uniform air distribution, the contaminant accumulation occurs in the stagnant zone and leads to high exposure risk. A high supply airflow rate increases the air mixing and contaminant dilution but also the risk of the draft sensation. This study proposes dynamic stratum ventilation with variable supply air direction. The variable supply air direction is achieved by a supply grille with swing flaps. Experiments are conducted with various combinations of the constant/variable supply air direction, high/low supply airflow rate, and different contaminant source locations. The impact of different supply modes of stratum ventilation on the airflow and contaminant distribution characteristics are investigated. For stratum ventilation with the variable supply air direction, the turbulence intensity is quadratic polynomial correlated to the mean air velocity with a coefficient of 0.9853 because the periodically changed supply air direction affects the velocity fluctuation. Stratum ventilation with the variable supply air direction has airflow with the β-value of 1.37–1.59. The different air supply modes influence the horizontal CO2 distribution differently regarding the location of the contaminant source, which provides new insights into indoor air quality control under stratum ventilation. When the contaminant source is in the mixing zone, stratum ventilation with a high supply airflow rate and variable supply air direction can effectively reduce the draft risk and contaminant concentration.

Simulation of Influencing Factors of Buried Pipeline Interfered by Subway Stray Current

The degree of interference of stray currents generated by urban rail transit to nearby buried pipeline was governed by a variety of factors. The buried pipeline model containing the subway return current system was built by COMSOL software, and the fluctuation characteristics of pipeline potential under single and bilateral power supply modes were analyzed to determine the influence of subway return current system parameters and soil resistivity and pipeline corrosion layer resistivity on pipeline potential, while the distribution of pipeline potential under non-uniform soil model was calculated. The results show that when the locomotive traction current and rail longitudinal resistance are doubled, the fluctuation degree of pipeline potential is approximately the same multiple. When the soil resistivity is 1000Ω·m or the pipeline anti-corrosion coating resistivity is 106Ω·m, the pipeline is free from stray current interference. The rail ground transition resistance is not a significant factor of pipeline potential fluctuation. The operation of the train causes the corrosion sate of the pipeline to change constantly. When the longitudinal soil resistivity is unevenly distributed, the increase of soil resistivity at the traction substation side leads to the overall positive shift of pipeline potential and further intensification of pipeline corrosion. The simulation results provide a reference for the railway department and pipeline department in the reasonable planning and layout of rail transit and pipeline.

Optimal Mode of Interaction between Rail and Ground Urban Passenger Transport within the TIH

The development of the infrastructure of transport interchange hubs is currently necessary to meet the growing demand for passenger services and to prevent infrastructural constraints on technological modernisation of entire transport system. Large-scale infrastructure projects are of a pronounced complex nature, involving many related industries in their sphere, which ultimately leads to an additional increase in GDP. A modern transport interchange hub is a public and business centre that ensures the quality of services, safety, technological reliability and creates an active business environment based on development of passenger infrastructure. Considering the latest global trends in the field of passenger transportation that englobe multimodality, speed, comfort and safety of passenger transportation, there is a pronounced need to develop modern transport interchange hubs.Minimisation of passenger transfer time between interacting modes of transport at TIH can be achieved by coordinating contact timetables of different modes of transport. To do this, it is necessary first, to solve the problem of determining the optimal mode of interaction between ground urban passenger and rail transport.The objective of the study described in the article is to determine the mode of supply of the units of ground urban passenger transport, which ensures the minimum time for a passenger to stay at TIH in accordance with the timetable of electric trains regarding the considered TIH. To reduce the dimension of the problem, it is assumed that all electric trains will have the same composition.The methods of scheduling theory were used to solve the problem in the context of the study that resulted in a formalised problem of determining the optimal mode of interaction between ground urban passenger transport in transport interchange hubs illustrated by the example of interaction of rail and urban road transport and considering all existing constraints.

Research and Application on High Quality Power Supply Technology of New Distribution System

Under the dual-carbon target, the intermittent grid-connection of high-permeability distributed power generation and random charging of large-scale electric vehicles increase the volatility and randomness of the distribution network. Meanwhile, the coupling correlation between the power network, information network and social network will be significantly enhanced. In view of the highly uncertain operation of the new distribution system, under the existing distribution network operation control and operation and maintenance management system, This paper puts forward the realization mode of high quality power supply for the new distribution system from three aspects: the adaptability of the grid, the overall perception ability and the improvement of the operation control ability.

Research on Application of Three Closed-loop Autonomous Current Sharing Control Technology in Artillery Power System

The new artillery power system adopts the power supply mode of multiple power modules in parallel, which has the advantages of strong versatility, high power, high reliability, and low cost. The main difficulty lies in the current sharing of the power supply modules. Aiming at the shortcomings of traditional current sharing method such as low current sharing accuracy, poor dynamic response, poor output voltage stability, and low anti-interference ability, this article analyzes the necessity of parallel power supply current sharing and the principle of traditional average current sharing method, based on average current sharing method, a three-closed-loop autonomous current sharing control method is proposed, and a system model of power supply modules operating in parallel is established to realize the intelligent and autonomous average current distribution of power supply modules operating in parallel in the artillery power system to meet the power required by the load in the system. Through simulation analysis and prototype test, it is verified that the three closed-loop autonomous current sharing control has the advantages of high current sharing accuracy, fast dynamic response, good stability and strong robustness.

Investigation on Induced Energy Extraction from High-Voltage Transmission Lines Based on Three-Coil WPT Systems

In order to realize an online power supply, this article develops an explicit design of induction power extraction technology combined with wireless power transmission (WPT) technology. Unlike the power supply mode of traditional batteries of online monitoring devices of high-voltage transmission lines, this technology solves the short battery life cycle problems. First, the principle of induction power extraction is analyzed. Based on the equivalent circuit of the mutual inductance model, expressions of induction power extraction without and with core saturation are derived, respectively. According to the current transformer (CT) magnetic coupling diagram, the open-circuit voltage of the secondary side of the CT is deduced. Therefore, the CT material and size could be selected. The CT coupling model is used to equivalent the current transformer to the ideal voltage source. Then, the four basic topological spaces of the magnetic coupling resonant WPT system are analyzed and calculated, and the efficiency of the SS topology WPT system is analyzed. Furthermore, aiming at long-distance power transmission, this article described the building of a three-coil WPT system and the analysis of the corresponding transmission efficiency and output power expression. With the aid of Maxwell, the technology proposed is simulated based on a 110 kV high-voltage transmission line with 1.2 m as the transmission distance of the system. Finally, the influence of a coupling coefficient and load resistance on the transmission characteristics of the multicoil system is obtained. Consequently, the simulation results with a system output power of 14.4 W verify the effectiveness of the technology.

Study on hot air heating characteristics of greenhouse in cold region

Agriculture is the main industry in northeast China. As an important part of facility agriculture, agricultural greenhouses are playing a more and more important role. Due to geographical location, Northeast China is cold in winter, and the solar radiation energy is less, therefore, the large-span greenhouses commonly used in northeast China are prone to uneven temperature and insufficient heating. In this paper, in order to solve the phenomenon of uneven air flow field, humidity field and temperature field in greenhouse, based on AIRPAK simulation, four kinds of hot air heating return air modes, such as upper air supply and lower air return mode, lower air supply and upper air return mode, two-side air supply mode and left air supply and right air return mode, we explored the influence of temperature field, humidity field and air flow field in greenhouse. The results showed that the heat load of the greenhouse in winter is 161.51 kW, using two-side air supply mode is the best way. The air supply wind speed is 1.6 m/s, and the return wind speed is 3.1 m/s. The environment of the greenhouse can be maintained at about 15°C day and night, and the relative humidity is relatively uniform. In the crop growing area, the wind speed is between 0 m/s and 0.25 m/s. According to this research, suitable crops can be selected for reasonable planting and distribution in the greenhouse to maximize productivity.

Electrochemical oxidation degradation of Rhodamine B dye on boron-doped diamond electrode: Input mode of power attenuation

Electrochemical oxidation is a rapid and efficient technology to remove organic matter from wastewater, but the most obvious defects are low current efficiency and high energy consumption. This paper presents a novel power supply mode with power attenuation. The attenuated power is periodically input to the reaction system to improve the average current efficiency and reduce energy consumption. The removal efficiency, current efficiency and energy consumption of treating Rhodamine B were compared between the two modes of power attenuation and the conventional direct current. Applying current attenuation in the step-Mode A1, 98.58% Rhodamine B was decomposed and the COD removal efficiency was 91.47%. The current efficiency reached 18.49% and electrocal energy consumption was only 44.58 kWh∙m−3. Under the conditions of the same removal efficiency of Rhodamine B, the current efficiency of Mode A1 was 2.04 times larger than that of Mode D1, and the energy consumption was only 45.41% of Mode D1. Five cycles of experiments show that the boron-doped diamond electrode has obvious stability and reusability in the electrochemical oxidation process. ·OH was the main active substance involved in Rhodamine B degradation. The power attenuation mode to treat Rhodamine B dyes electrochemically will be the most promising saving energy method for efficient processing dyes wastewater in the future.

A thermal balance method for measuring thermal conductivity by compensation of electric cooling or heating based on thermoelectric modules

To achieve the accuracy and convenience of thermal conductivity measurement, a thermal balance method for measuring thermal conductivity by compensation of electric cooling or heating based on thermoelectric modules is proposed in this paper. In this method, the thermoelectric module is regarded as the compensation unit to achieve the thermal balance between the compensation and test sides. Using the balance principle, the sample's thermal conductivity to be measured can be obtained by knowing the thermal conductivity of the compensation side. According to theoretical and experimental research, the compensation model is divided into self-supply energy and energy supply modes, and the law of thermal conductivity changes in thermoelectric modules in the two supply modes is summarized. To verify the feasibility of the thermal balance method, the thermal conductivity of alumina ceramics and polymethyl methacrylate (PMMA) materials with large differences in thermal conductivity were measured. The experiment proved that the thermal conductivity of alumina ceramic is 19.23 W/mK, slightly smaller than the standard value. The average thermal conductivity of PMMA is 0.21 W/mK, consistent with standard values. Taking the experiment conditions and error into account, the data are effective, which verified the feasibility of this method.

Receding Horizon Optimization of Ethylene Cracking Operation and Scheduling under Supply Chain Fluctuations

The global supply chain is experiencing ongoing turmoil after COVID-19, which inevitably affects the supply and demand of the chemical industry. Ethylene plants are regarded as one of the most profitable chemical industry chains, and thus, there is a need to track fluctuations in the supply chain and responsively adjust their operations and scheduling decisions to achieve optimal economic benefits. However, previous studies about ethylene cracking optimization are mostly limited to fixed supply chain parameters and cannot meet the need for real-time updates according to supply chain fluctuations. To address this problem, we propose an ethylene cracking optimization framework which combines parameter prediction and receding horizon optimization (predictive RHO) for real-time optimal operation and scheduling under supply chain fluctuations. This optimization framework uses historical supply chain data (supply quantities, feedstock prices, and product prices) to predict future parameters and uses the predicted parameters to optimize the operation and scheduling of ethylene cracking furnace systems in a receding horizon way. Two industrial case studies were used to validate the efficacy of the proposed optimization framework. In case 1, the predictive-RHO framework achieved comparable economic profits of 147,370 and 146,483 $/day without violating daily inventory constraints (vs 151,204 $/day from the original model violating inventory constraints) and a faster calculation speed of 40 s (vs 32 min) under two fluctuating feed supply modes. In case 2, predictive RHO improves economic profits by 1.8% through integrating operations with scheduling and 1.1% by tracking the feed and product price fluctuations. These two cases show the strong capability of predictive RHO in tracking supply chain fluctuations and improving the inventory management level as well as the economic profits of ethylene cracking plants.

An Intelligent System with Multiple Power Supply Modes

A low-cost and intelligent power supply system with an STC15 single-chip microcomputer as the main controller is designed. The single chip monitors the mains voltage and controls the relay to switch between the mains and battery power supply. Battery constant current, constant voltage, and floating charge intelligent charging management are achieved through the battery voltage execution. Through the ESP8266WIFI module networking, we can access weather information, and weather judgment, and choose whether to enter the battery mode, which can better protect the power system. The experimental results show that the system can operate reliably and complete the switch between mains supply mode and battery supply mode quickly.

Исследование характеристик U-образного плазменного канала импульсных ксеноновых ламп

The paper presents main results of investigating electrical parameters and characteristics of the pulsed xenon lamp ultraviolet radiation with a U-shaped plasma channel and caprod current leads. The gas-discharge lamp design feature suggests presence of the ballast transelectrode volumes contributing to the xenon escape from the discharge and the radiation acting from one part of the U-shaped plasma channel on the other. Literature sources devoted to the specified phenomena were analyzed. Factors influencing the xenon plasma thermophysical state were established. Due to the lack of techniques for registering the pulsed radiation in a narrow spectral range of 200--300 nm, measurement techniques and investigation hardware were considered in detail. The time interval for establishing the gas-dynamic equilibrium in a pulsed xenon lamp in the process of its entry into the nominal operating mode was determined by calculation and experiment. Studies of the Vt transelectrode volume effect on characteristics of the pulsed xenon plasma were carried out in the range of 0.16 < Vt /Vi < 0.3. It was established that the possible factors leading to a decrease in the current density and intensity of the UV radiation included the modes of electrical supply and evaporation of the quartz shell limiting the discharge. It was shown that self-radiation return in plasma contributed to an increase in the current density of the pulsed xenon lamp

Research on electric vehicle charging load based on the monte Carlo

With the increasing number of electric cars, they may become the most important load in the grid of the future. Due to the randomness of electric vehicles access to the grid, when large-scale electric vehicles are linked to the grid, they will fluctuate on the grid, resulting in the failure of the power supply mode and operation control means of the traditional distribution network to attain the optimal result. In view of this phenomenon, based on the Monte Carlo calculation and simulation, the charging load of electric vehicles is predicted, which can achieve comprehensive prediction under different kinds of electric cars, different battery capacities, different charging methods, etc, and provide theoretical and technical support for the effect analysis of electric vehicles access to power grid.

A Multipurpose and Power Quality Improved Electric Vessels Charging Station for the Seaports

To avoid air and noise pollution on seaports, the use of electric vessels and shore-to-ship power supply based charging station on seaports are in trend, which is also known as cold ironing (CI) infrastructure. In the starting stage, electric vessels charging stations are being implemented on the most busiest commercial ports, where modern electronic devices are used to serve different types of vessels. These devices only take care of the quality of output power. However, on the input side, it creates a serious harmonic issue. During CI, megawatt range of power is supplied to the ships, so generated harmonics and interharmonics in the high-power supply based charging system become more dangerous for the grid. In this article, we propose a novel power quality improved cold ironing (PQICI) system (charging mechanism) to overcome this issue. Moreover, due to inherent multipurpose useability, this novel PQICI is able to supply different types of power to various types of vessels, such as ac power, dc power, 50 Hz frequency, 60 Hz frequency, single phase, three phases, three-wire network, four-wire network, five-wire network, and different ac and dc voltages. Furthermore, this PQICI supply system is capable of serving four vessels at a time. In every type of loading condition with different kinds of power supply mode, the PQICI maintains the power quality on the input side, with fulfilling the varieties of the power demand of vessels. The capability of the developed “PQICI” system is tested for different types of ships and vessels on the simulation platform as well as through real-time hardware-in-the-loop experimentation. On IEEE standard 519, satisfactory test results on both platforms show the efficiency of the developed system and its control mechanism.