Comprehensive Utilization Efficiency Research Articles

Multi-objective Optimization of Park-level Integrated Energy System: Model and Analysis

Using an integrated energy system can increase the proportion of renewable energy and comprehensive energy utilization efficiency, which help solve problems such as environmental pollution, carbon emissions, and depletion of fossil energy. The actual construction and operation of an integrated energy system need to consider not only the economy, but also the energy consumption and carbon emissions. Therefore, it is necessary to establish a multi-objective optimization model of the integrated energy system to achieve the combination of economics, energy saving and environmental protection for the system is optimal. In this paper, a multi-objective optimization model for an integrated energy system is established, and the influence of different decision makers’ preferences on the optimization results is studied through the model.

Simultaneous removal of CO2 and H2S from coalbed methane in a membrane contactor

Coalbed methane (CBM) is an unconventional natural gas, and vigorous development of CBM has great significance for improving the current status of global coal mine safety production, alleviating market gas supply pressure, and protecting the ecological environment. CBM mainly consists of CH4, CO2 and a small amount of H2S. In order to improve the comprehensive energy utilization efficiency of CBM, it is necessary to capture both CO2 and H2S from CBM. In this paper, a comprehensive 2D model was established by COMSOL Multiphysics for simultaneously removing CO2 and H2S in CBM. The K2CO3/potassium lysinate (PL) mixed solution was employed as the absorbent in a membrane contactor. The impacts of gas and liquid velocities, liquid concentration and temperature on the absorbent performance were studied. The results obtained by using the simulated membrane contactor were consistent with the experimental data in the literature. The results indicate that the gas velocity was the most significant influential factor to the gases removal efficiency. Furthermore, it was concluded that the K2CO3/PL mixed solution had a better decarburization performance than the single K2CO3 solution. The optimal operating conditions for simultaneous removal process by using K2CO3/PL mixed solution were obtained by response surface method. More importantly, the blends of amino acid salts and carbonate solution have great prospects in the membrane absorption of acid gases from CBM.

Comprehensive utilization of waste heat produced by fuel cell on manned space process

In order to solve the problem of large amount of waste heat generated by aerospace fuel cells and improve the comprehensive energy utilization efficiency of fuel cells, the proposes of a comprehensive utilization plan of fuel cell waste heat for the working conditions involved in manned spaceflight, including gas preheating, system insulation and microorganisms were designed in this paper. The waste heat were proposed to be used in cultivation, plant cultivation, urinary treatment of ring hole bio-protection system, harmful gas and carbon dioxide removal, and the construction of heat utilization methods and processes. Combined with high-efficiency phase change material heat storage, a comprehensive utilization method of fuel cell waste heat were designed. The comprehensive utilization of waste heat provides an effective path for optimizing the spacecraft system for improving the comprehensive utilization efficiency of fuel cells.

Overview of Regional Integrated Energy System Operation Optimization Based on Comprehensive Demand Side Respons

Regional Integrated Energy System (RIES) provides a new way to solve the energy dilemma. In order to improve the economic benefits of a regional integrated energy system, a regional integrated energy system with energy storage considering Integrated Demand Respones (IDR) is proposed. Under the premise of not affecting user comfort, fully mobilizing user-side resources can improve the comprehensive utilization efficiency of energy, reduce energy costs, and consume more renewable energy. This paper introduces the concept of IDR, layered interactive architecture and interaction mechanism, analyzes the multi-energy, and focuses on the analysis of integrated energy system scheduling considering IDR uncertainty. Finally, the key scientific issues in IDR research are summarized, and future research directions are prospected.

Evaluation of comprehensive potential productivity and resource utilization efficiency of Camellia oleifera in Jiangxi Province, China

As an area suitable for the plantation of Camellia oleifera, Jiangxi had a low degree of development and utilization. Evaluating its potential productivity and resource utilization efficiency could provide reference for optimizing C. oleifera planting division, increasing yield and rationally utilizing land resources. Natural production potential of C. oleifera in Jiangxi was estimated by stepwise revised potential attenuation method. The comprehensive potential productivity was estimated by combined with social efficiency coefficient, with the resource utilization efficiency being evaluated. There were three main results. 1) Potential productivity of C. oleifera in Jiangxi varied from 10229 to 17724 kg·km-2, which decreased from the south to the northwest, with an average potential of 12550 kg·km-2. After classification, the area with higher and highest potential productivity reached 51656 km2, accounting for 31.1% of the total area. Among the cities, Ganzhou had the highest potential productivity. 2) The changes of potential productivity of C. oleifera ranged from 2223 to 3857 kg·km-2, with small regional difference for various levels. The resource satisfaction rate ranged from 69.3% to 122.7%, with small regional difference. The resource utilization efficiency varied from 49.1% to 85%. Regional utilization rate at all levels differed obviously. 3) The estimated comprehensive potential productivity was in line with the real production of C. oleifera in Jiangxi, and the assessed resource utilization efficiency was consistent with natural and social conditions. These results could be used as a reference for related research and policy making.

Operational optimization of wastewater reuse integrated energy system

With the rush in global energy demand and the popularization of renewable energy utilization, the integrated energy system has been rapidly developed, and there have been diverse comprehensive energy resources, which includes wind energy, solar energy, sewage etc. In order to improve the comprehensive energy utilization efficiency of energy systems with sewage resources, this paper proposes an integrated energy system of wastewater reuse and an optimal operation model of it. Firstly, this paper proposes an integrated energy system operation control strategy based on sewage source heat pump and biogas trigeneration energy production. Secondly, the genetic algorithm model with the objective function of comprehensive energy utilization efficiency and economic operation cost is established. Finally, this paper adopts a sewage treatment system area as the simulation target to carry out the simulation analysis of wastewater reuse integrated energy system (WRIES) operation, and constructs an operation optimization scheduling scheme. Simulation results show that compared with no optimization, the operating cost of the system can be reduced more than 9%, and the renewable energy utilization rate can be increased more than 5%. After the thermoelectric ratio adjustment, the results of system operation optimization can be further improved.

Energy and optical analysis of photovoltaic thermal integrated with rotary linear curved Fresnel lens inside a Chinese solar greenhouse

In this paper, a cylindrical Fresnel lens concentrating photovoltaic/thermal (CPV/T) system is established in the non-planting area of the Chinese solar greenhouse. The system changes as the solar elevation angle changes between the summer solstice and the winter solstice, ensuring that the light is incident perpendicular to the lens. A row of Fresnel lens at this location does not block the photosynthetically active radiation of the plants in the planting area, and only reduces part of the direct light from the north wall of the greenhouse. The space utilization rate of non-planting space is 18.2%. Through optical simulation, the acceptance rate has little effect when the axial incident angle is within 10°. In contrast, the concentrating performance of the cylindrical Fresnel lens is better than that of the elliptical and parabolic Fresnel lenses. In actual weather, an experimental study was conducted on a concentrating photovoltaic/thermal system in which a gallium arsenide concentrating cell was used as a receiver. The main parameters such as temperature distribution of the concentrating photovoltaic/photothermal system receiver, output power and thermal power, utilization efficiency of electric energy and thermal energy were tested. The test results under clear sky conditions show that the maximum power generation efficiency is about 18% at noon (11:00–13:00), the maximum thermal efficiency of cooling water is about 45%, and the total efficiency of thermal and electrical power is about 55%. Combined with facility agricultural engineering, it comprehensively solves the problem of land resource utilization and comprehensive utilization efficiency of solar energy system.

Research on energy efficiency management method of AC/DC hybrid distribution system

With the increasingly serious problems of fossil energy crisis and environmental pollution, vigorous development of Distributed Renewable Energy has become an important means of energy structure reform and energy consumption transformation. On the distribution side, AC/DC hybrid distribution system has been widely studied for its advantages of accessing multiple types of energy, satisfying diversification energy demand, realizing multi-energy complementation and improving grid security. The energy efficiency evaluation and management of AC/DC hybrid system are of great guiding significance to the planning and design of AC/DC system. However, traditional energy efficiency management mainly reduces primary energy consumption by saving electricity. For AC/DC systems with multiple distributed energy sources, it is difficult to reflect the efficiency level of the whole system by considering a single technology or a single part of energy efficiency management. Aiming at the characteristics of AC/DC hybrid distribution system, this paper studies the energy efficiency management method of the system. Firstly, combined with energy efficiency evaluation and system economic analysis, energy efficiency evaluation index of AC/DC hybrid distribution system are formulated. Secondly, the energy efficiency management method is studied through the study of adjustable load, transferable load and different types of load overall management method. Then the method of combining power quality and energy efficiency is studied. Finally the interaction between source and load is studied to improve the energy efficiency of the system. The energy efficiency management method proposed in this paper can fully tap the potential of load adjustable and energy saving, improve the comprehensive energy utilization efficiency of the system, which provides a basis for the engineering application of AC/DC hybrid power grid.

Performance analysis of solar assisted heat pump coupled with build-in PCM heat storage based on PV/T panel

PV/T (photovoltaic/thermal) technology is a combination of PV module (photovoltaic utilization) and collector (photothermal utilization), which can improve the comprehensive utilization efficiency of solar energy and has a broad application prospect. In this paper, PV/T module is coupled with heat pump evaporator to form a direct-expansion solar PV/T heat pump which is suitable for heat application in high latitude area. To achieve stable residential heating, a solar PV/T heat pump system coupled with build-in PCM (phase change material) heat storage is therefore proposed and simulated. Meanwhile, the mathematical model of solar PV/T heat pump coupled with build-in PCM heat storage system is established and verified. The simulation results show that the temperature of underfloor heating which using build-in PCM heat storage can reach 22–31 °C after 39 h when the circulating water is 40 °C. Moreover, the heating COP (Coefficient of Performance) increases with the increase of solar radiation, ambient temperature and area of PV/T collector, and decrease of wind speed, respectively. A 20 m2 PV/T panel module can output 21.4% of the electricity to power grid when the solar radiation intensity is 600 W/m2 and meet the heat demand of a 100 m2 room while maintain the operation of the system. Meanwhile, the heating COP can reach 5.79 which is 70% higher than the conventional air conditioning system and the electrical, thermal, overall efficiencies are 17.77%, 55.76% and 75.49%, respectively.

Business classification of Power Grid Enterprises in the development environment of Energy Internet

Energy Internet is centered on electricity, based on a strong smart grid, and deeply integrates advanced information and communication technology, control technology and advanced energy technology to support the clean and low-carbon transformation of energy and electric power, comprehensive utilization efficiency optimization of energy, and the access of flexible and convenient multiple entities, which is a smart energy system with the characteristics of green safety, ubiquitous interconnection, efficient interaction, and intelligent openness. This article focuses on the impact of the development of the Energy Internet on power grid companies and the main business of power grid companies in the future development environment of the Energy Internet, providing references for the transformation and development of power grid companies.

First-principles investigation on electronic structure and solar radiation shielding performance of Tl<sub>0.33</sub>WO<sub>3</sub>

<sec>With energy-saving and emission-reduction have become the theme of today's social development, the theoretical design and research of novel transparent heat insulation materials for windows, which can save energy and improve the comprehensive utilization efficiency of solar energy, are particularly crucial.</sec><sec>In this paper, a calculation method based on DFT(density functional theory) is used to study the lattice parameters (the geometric structure of h-WO<sub>3</sub> crystal was optimized by calculation) electronic band structure, formation energy, and optical properties of pure hexagonal phase tungsten trioxide(h-WO<sub>3</sub>) before and after doping with Tl. The calculated results indicate that the lattice volume increases and the total system energy decreases to a negative value after Tl-doped h-WO<sub>3</sub>, while the system has better stability; The electron band structure changes greatly after doping, but the material still maintains n-type conductivity. In the meantime, the optical properties of the material also changed, h-WO<sub>3</sub> had no near-infrared absorption performance before Tl-doping, and Tl<sub>0.33</sub>WO<sub>3</sub> after Tl-doped had strong near-infrared absorption performance. On this basis, the solar radiation shielding performance of h-WO<sub>3</sub> before and after Tl doping has been studied. The results show that pure h-WO<sub>3</sub> has no solar radiation shielding performance, while Tl<sub>0.33</sub>WO<sub>3</sub> thin films after Tl-doped h-WO<sub>3</sub> have high transparency in visible light region and strong absorption in near infrared radiation. The calculation results provide a theoretical basis for the application of transparent thermal insulating material for windows of Tl-doped h-WO<sub>3</sub>.</sec>

Performance analysis of a wind supercharging solar chimney power plant combined with thermal plant for power and freshwater generation

In this article, a wind supercharging solar chimney power plant combined with seawater desalination and waste heat (WSCPPDW) and a solar chimney power plant combined with seawater desalination and waste heat (SCPPDW) were proposed. Both of them were equipped with a spiral exhaust gas heating channel (SGC), and the main difference between the two was the presence or absence of the wind supercharging device. Then the physical and mathematical models were constructed for evaluating the output characteristics under different conditions. It was found that the rise of chimney height and flue gas temperature were both beneficial to the overall performance of WSCPPDW and SCPPDW. The reduction of seawater thickness improved the entirety output characteristics under adequate irradiance conditions. As the solar irradiance and flue gas mass flow increased, the electricity generation was augmented, but the freshwater production and comprehensive efficiency represented a downward trend. Besides, the performance of WSCPPDW was always better than that of SCPPDW, and the energy comprehensive utilization efficiency of WSCPPDW was increased by 15.4% throughout the utilization of high-altitude wind. Concretely, the hourly freshwater yield, power generation and comprehensive efficiency of WSCPPDW reached 193.7 kW, 17.2 ton/h and 13.5% respectively.

Energy transfer and utilization efficiency of regenerative braking with hybrid energy storage system

In order to increase the recovery and utilization efficiency of regenerative braking energy, this paper explores the energy transfer and distribution strategy of hybrid energy storage system with battery and ultracapacitor. The detailed loss and recovery of energy flow path are analyzed based on the driving/regenerative process of dual supply electric vehicle. Considering the charge-discharge loss of ultracapacitor and battery as well as DC/DC converter loss, a distribution strategy of comprehensive efficiency optimum is proposed for power allocation to maximize energy recovery and utilization efficiency. The quantitative formulas suitable for HESS are deduced to evaluate the regenerative energy recovery rate. Through comparing different power allocation strategies and regenerative braking strategies, it is verified that the proposed allocation strategy can improve the comprehensive energy utilization efficiency of energy storage system.

Chemical constituents, biological functions and pharmacological effects for comprehensive utilization of Eucommia ulmoides Oliver

Eucommia ulmoides Oliver is a native plant and valuable tonic Chinese medicine in China with a long history, great economic value and comprehensive development potential. Traditionally, the comprehensive utilization rate of E. ulmoides Oliv. is still very low, only bark has been used as medicine and other parts of Eucommia ulmoides Oliv. cannot be fully utilized, even the leaves have been well utilized in food products in Japan in the past decades. In order to improve the comprehensive utilization efficiency of E. ulmoides Oliv., in this review, we summarized the varieties and contents of main active compounds, biological functions and pharmacological effects in different parts of E. ulmoides Oliv. The findings suggest that other parts of E. ulmoides Oliv. could replace the bark of E. ulmoides Oliv. to some extent besides of their respective applications. The unique and extensive physiological functions between different parts of E. ulmoides Oliv. indicate that the comprehensive utilization of E. ulmoides Oliv. has a wide space to develop, which is also an effective way to protect E. ulmoides Oliv. resources and improve its the utilization rate.

Preliminary study of wind supercharging solar chimney power plant combined with seawater desalination by indirect condensation freshwater production

In this study, the physical and mathematical models of wind supercharging solar chimney power plant combined with seawater desalination by indirect condensation freshwater production (WSSCPPSDIC) were proposed. The numerical simulation was carried out for analyzing the flow field characteristics of WSSCPPSDIC. Subsequently, a comparison of solar chimney power plant (SCPP), solar chimney power plant combined with seawater desalination by indirect condensation freshwater production (SCPPSDIC) and WSSCPPSDIC was conducted in different rotational speed. It was found that the ingenious and special condenser combined in the integrated system could preheat the seawater and realize the full utilization of the latent heat of condensation released by water vapor. Besides, the negative pressure generated by the wind supercharging system installed at chimney exit remarkably increased the electricity production. Generally, WSSCPPSDIC could effectively improve the freshwater output and the solar energy comprehensive utilization efficiency, specifically 9.805 ton/h and 16.73%.

A novel efficiency assessment criterion for thermo-economic analysis of Gas-Steam Combined Cycle combined heat and power

Gas-steam combined cycle (GSCC) plants are among the best technologies for power production, in particular when operating in combined heat and power (CHP) generation. As far as we know, there is not any efficiency assessment criterion for thermo-economic analysis of GSCC-CHP plants until now. To solve this problem, this paper proposes a novel efficiency assessment criterion through establishing a mathematical model of heat-consume apportionment and then defining a set of thermo-economic performance indexes for the GSCC-CHP plants, based on the basic principle of heat quantity method by synchronically considering some predefined parameters such as energy utilization efficiency of gas turbine units and the unit comprehensive energy utilization efficiency. With the multi-condition analysis of the changed heat load, extraction pressure and water recovery rate, it verifies the feasibility of the efficiency assessment criterion.

Variation on sandbar of tributary in Xiaolangdi Reservoir on Yellow River, China

Sandbar development would stop the water and sediment exchange between main river and tributary and even influence the normal reservoir opeartion. From the surveyed data of reservoir built many years ago, it shows that when there is a bar in tributary mouth, the tributary volume below the bar will become nullification during the period of flood control or water and sediment regulation of reservoir. There are more tributaries in Xiaolangdi reservoir than the others that it occupies 41.3% of the total initial volume of tributary volume. Obviously, the effective use of tributary volume has been important influenced by comprehensive utilization efficiency of reservoir scheduling, such as flood control, sedimentation reduction and comprehensive utilization. Results of Xiaolangdi Reservoir mobile-bed physical model experiments show that tributary is equivalent to lateral extension of river bed, the tributary intrusion deposition process have strongly relations with the factors, such as original topography, river bed deposition shape and its regime, process with input discharge and input sediment, and method of reservoir regulation. The variation trends of main river and tributary terrain forecasted by model test are basically in accordance with field surveyed data. The results could be used for research, design, and forecasting of reservoirs in sediment-laden river.

Physical Model Results on Intrusion Between Channel and Tributary in Xiaolangdi Reservoir

Interaction between reservoir sedimentation topography and water and sediment transportation characteristic is deeply affected the reservoir storage capacity. From the surveyed data of reservoir built many years ago, it shows that when there is a bar in tributary mouth, the tributary volume below the bar will become nullification during the period of flood control or water and sediment regulation of reservoir. There are more tributaries in Xiaolangdi reservoir than the others that it occupies 41.3% of the total initial volume of tributary volume. Obviously, the effective use of tributary volume has been important influenced by comprehensive utilization efficiency of reservoir scheduling, such as flood control, sedimentation reduction and comprehensive utilization. Results of Xiaolangdi Reservoir mobile-bed physical model experiments show that tributary is equivalent to lateral extension of river bed, the tributary intrusion deposition process have strongly relations with the factors, such as original topography, river bed deposition shape and its regime, process with input discharge and input sediment, and method of reservoir regulation. The variation trends of main river and tributary terrain forecasted by model test are basically in accordance with field surveyed data. Based on the physical graphics revealed by mobile-bed physical model experiments, a method of tributary diversion ratio is preliminarily generalized for calculation and is verified by field surveyed data. The results could be used for research, design, and forecasting of reservoirs in sediment-laden river.

汉江上游梯级水库联合调度研究

汉江上游缺乏梯级水库联合调控中心，各水库单独调度运行，导致梯级水能资源利用率较低。引汉济渭黄金峡、三河口水电站正在建设，新形势下汉江上游梯级调度中心位置的论证已迫在眉睫。本文采用大系统分解协调理论对汉江上游梯级水库联合调度进行了研究。结果表明：引汉济渭调水后，各梯级电站均获得了较大补偿效益，梯调中心由安康水库转移至三河口水库。研究成果对于汉江上游梯级水库联合调度运行、提高水资源综合利用效率具有重要的理论意义和应用价值。 The reservoirs located in the upper Hanjiang River lack a cascade hydropower station joint control center, which are operated separately, leading to the lower water resources utilization efficiency. The Huangjinxia and Sanhekou hydropower stations are constructing; the argument on cascade reservoir operation center of the upper Hanjiang River is urgent. In this paper, the cascade reservoirs in the upper Hanjiang River are studied by large system decomposition and coordination theory. The results show that each cascade hydropower station has received better compensation benefits, and the cascade control center from the Ankang reservoir should be transferred to the Sanhekou reservoir, owing to the water diversion from the Han to the Wei River. The research has an important theoretical significance and application value for the joint operation of cascade reservoirs in the upper Hanjiang River as well as the improvement of the comprehensive utilization efficiency of water resources.

Evaluation of water resources comprehensive utilization efficiency in the Yellow River Basin

This study investigated appropriate indicators using the trapezoidal fuzzy number method, and constructed an evaluation index system for water resources comprehensive utilization efficiency (WRCUE). A WRCUE evaluation model is applied to areas in the Yellow River Basin in China using a genetic projection pursuit method. Results show that WRCUE is well developed in Shanxi, Shandong, and Henan provinces, moderately developed in Shanxi, Inner Mongolia, and Sichuan provinces, and poorly developed in the Ningxia Autonomous Region, Gansu Province, and Qinghai Province. According to the capacities of provinces, related measures are proposed.