压缩空气储能系统是一种新型大规模电力储能系统,目前已发展到第三代,系统效率是评价系统性能的重要指标,已有的研究很少基于相同的系统配置定量研究三代系统效率的差异.本文基于相同的系统配置,针对三代典型系统分别建模,比较各系统能量转换效率,分析能量损失分布,同时研究压缩机压比对系统效率的影响.仿真结果表明,先进绝热压缩空气储能系统回收利用压缩热,效率分别为63.17％(储热介质为导热油)和58.71％(储热介质为水),高于传统系统(44.95％)和带回热的系统(49.04％).提高压缩机压比,对各系统的能量效率影响不同.本文仿真研究结果为提高对三代储能系统的热力性能认识提供了理论支撑.

Solar tower aided coal-fired power generation is a kind of technology which can improve the utilization of solar thermal energy and reduce coal consumption.In this technology,solar tower thermal energy with high temperature is coupled with the conventional coal-fired power generation systems.And the solar tower field generated high temperature steam to work in the coal-fired power plants.In this paper,the electricity generation and the composition thereof (generated from coal and solar energy) as well as techno-economic analysis during the whole lifecycle of an 1 000 MW solar tower aided coal-fired power generation system (STCG) are studied under variable direct normal irradiance (DNI) and grid power dispatching.The results show that the average solar-toelectricity efficiency of STCG is 18.2％,which is higher than common solar tower power plants.Levelized costs of electricity (LCOE) of STCG plant project is 0.319 yuan/(kW·h),and internal rate of return is 11.29％,which show a good profitability and a low investment cost.In addition,STCG can save 2.574 million tons of coal and reduce 7.238 million tons of CO2 emission compared with coal-fired power plant with the same power dispatching.When considering the costs of CO2 capture,the feed-in tariff subsidy should be 0.065 yuan/(kW.h) for STCG to have the same market competitiveness with the same capacity coal-fired power plants.

This paper presents an integration methodology for medium and high temperature solar aided coal-fired power generation systems. A set of preferred integration methods is proposed using analysis of pinch point, exergy and solar share and the application of system simulation methods. These methods can be used for hybrid (solar/ fossil) systems screening, pre-assessment and decision-making. Power plant annual performance is analyzed to confirm the validity of the abovementioned methods. The presented methodology has been applied into a 100 + 1000 MWe grade solar tower aided coal-fired power generation plant (STAPG). According to the proposed methodology, the best integration scheme is found for a scenario where high-temperature solar thermal energy is used for steam reheating, while the remaining solar thermal energy is used for feedwater heating providing the maximum utilization of solar energy. The analysis reveals that as much as 214.7 MWe could be generated using solar thermal energy under the best integration scheme. This accounts for 21.3% of total electricity produced, while representing more than twice as much the power produced by an equivalent stand-alone solar tower power plant of the same solar field size. Furthermore, solar-to-electricity efficiency of the hybrid system may reach 36.8%, with power block efficiency of 43.3%, and the coal consumption rate is 203.5 g/kW h. All these parameters are representative of the best scenario amongst the seven integration schemes studied in this paper.

In this paper, we conduct a techno-economic analysis of a 1000 MWe solar tower aided coal-fired power generation system for the whole life cycle. Firstly, the power output (from coal and solar thermal energy) under variable direct normal irradiance and grid demand are studied. Secondly, a financial assessment is performed, including profits and losses of the plant project. Thirdly, sensitivity analysis is taken on some external factors that can affect the cost or profits and losses of the plant project. The results indicate that the project has high profits with an internal rate of return (IRR) of 8.7%. In addition, the effects of solar tower field cost, power purchase agreement (PPA) price of solar thermal electricity, coal price, and the interest rate of debt on the main criteria decrease gradually. Therefore, it is better to improve solar tower technology first, and then look for low-interest debts from banks to cope with the reduction of PPA price of solar thermal electricity and the increase of coal price. Despite the introduction of solar tower field increasing levelized cost of electricity (LCOE), it contributes to the reduction of CO2 capture cost compared to the case of standard coal-fired power plants.

The energy penalty of MEA based post-combustion CO2 capture technology will reduce the efficiency of coal-fired power generation significantly. The introduction of solar energy to the capture system can compensate the CO2 capture penalty. This paper proposed three integrations of 1000 MW coal-fired power plant retrofitted with solar energy and post-combustion CO2 capture system (PP + Solar + PCC), which the solar energy is used to replace the 1st extraction to heat the feedwater or provide the MEA regeneration heat demand is the main difference in three PP + Solar + PCC both in thermal and economic. The 1000 MW coal-fired power plant, solar aided coal-fired power system and coal-fired power plant with post-combustion CO2 capture system (PP + PCC) are selected as the reference cases. By comparison of six systems, it was concluded that the integration of using solar energy to replace the first high pressure extraction and taking a part of intermediate pressure cylinder exhaust to provide the reboiler heat demand is the best in three strategies of PP + Solar + PCC. In addition, this paper analyzed the evaluation indicators variation with the changes of CO2 removal rate, solar collector field area, DNI, solar collector field cost, coal cost and carbon tax. (C) 2017 Elsevier Ltd. All rights reserved.

Solar tower aided coal-fired power generation system (STCG) is able to provide high solar utilization efficiency with low coal consumption rate. This paper compares performances of a solar tower aided coal-fired power plant, a solar tower power plant and a coal-fired power plant under different operative conditions. The comparison includes various solar multiple and thermal energy storage size. According to solar radiation resource and grid power dispatching demand, STCG, solar tower power generation system (STG) and coal-fired power generation system (CPG) work under off-design conditions all the year around. Results show that STCG has higher solar utilization efficiency than STG and lower coal consumption rate arid CO2 emission rate than CPG. In addition, solar-to-electricity exergy efficiency of STCG is at least 1.83% higher than that of STG. Compared to CPG, the 1000 MWe STCG can reduce coal consumption by 2.0 x 10(5) t/y, with the saving ratio being 10.4%. The annual average coal consumption rate of STCG is 27.3 g/kWh lower than that of CPG. In addition, the annual average CO2 emission rate of STCG is reduced by 10.1% compared with that of CPG. Solar tower aided coal-fired power generation can facilitate energy conservation and emission reduction of STG and CPG. (C) 2016 Elsevier Ltd. All rights reserved.

Polymethylmethacrylate (PMMA) plastic fiber has been used in daylighting system for a long time, however, the quantitative study of its optical properties is still limited. It has been verified in this paper that shortpass dichroic mirror (SDM) can effectively filter out up to 64% of infrared ray from high flux, resulting in small losses of visible spectrum of natural light. Experiments confirmed as well that SDM can significantly reduce infrared thermal effects effectively protecting PMMA plastic fiber. In addition, the effect of incidence angle on the attenuation of fiber is also measured. It has been proven that attenuation rate increases with the incident angle. Experimental data presented here can be used for daylighting system optimization using PMMA fibers. (C) 2016 Elsevier Ltd. All rights reserved.

The solar tower aided coal-fired power generation system (STCG) is based on a solar tower field and a conventional coal-fired power plant. Solar thermal energy is used to generate high-temperature and pressure steam to work in the coal-fired power plant. Indirect solar power generation and coal energy conservation goals can be achieved under this arrangement. The paper conducts a conventional and an advanced exergetic analysis of a 1000 MWe STCG. Exergy distribution of the system, exergy efficiency of each component and exergy destruction construction have been analyzed. Conventional exergetic analysis method has been used for exergy flow and loss distribution of STCG, whereas the advanced exergetic analysis method has been applied to exergy destruction of components, including endogenous and exogenous exergy destruction. These two methods complement each other and reveal the causes of exergy destruction in STCG. Results indicate that boiler and solar tower field systems are the components with the lowest exergy efficiency (53.5% and 26.0%, respectively). Total exergy losses of these two components account for more than 85% of all exergy losses of STCG. Exergy destruction of components is caused mainly by thermal performance of these components. Based on the degree of system and component association, the component ratio of endogenous and exogenous exergy destruction is different. Exogenous exergy destruction is directly proportional to the association degree. Connection complexity between a solar tower field and a coal-fired power plant system is the simplest, and 99.9% of solar tower exergy destruction is produced by the solar tower field itself. The results of this paper indicate that the boiler and solar tower field should be analyzed in detail when designing STCG systems. Before optimizing the system integration, thermal performance of components should be improved. Doing so, more energy from solar and coal can be converted to electricity, guiding the design and optimization of real demonstrators. (C) 2016 Published by Elsevier Ltd.

塔式太阳能辅助燃煤发电是将塔式太阳能所获得的热量与燃煤电站相同品位的能量相耦合,借助燃煤电站的发电系统,实现太阳能热的间接发电,该方法可以省却单纯塔式太阳能热发电所需的汽轮机、发电机和回热换热器等部件,从而降低太阳能热发电的初投资.由于太阳能热在系统中间接发电,如何准确评价太阳能在发电过程中的贡献度值得深入研究.基于热力学第二定律和热经济学基本原理,对塔式太阳能辅助燃煤发电系统中太阳能的贡献度进行研究,厘清太阳能热在系统中的分布关系,得出太阳能热的实际发电量和由于太阳能设备的投入而增加的度电成本.最后对某600 MW塔式太阳能辅助燃煤发电系统进行案例分析,验证该方法的可行性.该塔式太阳能辅助燃煤发电系统中,太阳能的发电量占4.24％,而其度电成本中太阳能所占比例仅有0.91％.

Solar aided coal-fired power plants utilize solar thermal energy to couple with coal-fired power plants of various types by adopting characteristics of different thermal needs of plants. In this way, the costly thermal storage system and power generating system will become unnecessary, meanwhile the intermittent and unsteady nature of power generation can be avoided. In addition, large-scale utilization of solar thermal power and energy saving can be achieved. With the ever-deepening analyses of solar aided coal-fired power plants, the contribution evaluating system of solar thermal power is worth further exploration. In this paper, five common evaluation methods of solar contribution are analyzed, and solar aided coal-fired power plants of 1000 MW, 600 MW and 330 MW are studied with these five methods in a comparative manner. Therefore, this study can serve as a theoretical reference for future research of evaluation methods and subsidies for new energy. (c) 2015 Elsevier Ltd. All rights reserved.

In this paper, a fiber optic daylighting system based on the parallel mechanism is designed and fabricated. This system is composed of 49 concentrating cells, which are arranged in a 7 x 7 array. The array consists of 48 sunlight-collecting cells and a sun position sensor using direct focus detection. A linear actuator, which is composed of two stepper motors and two roller screws, is used to drive the concentrating array to track the sun with the movement in a plane parallel to the plane containing the array of fiber optic collecting aperture. The solid angle of the sun tracking angle range for the concentrating cells is 4 pi/3 sr (covering 2/3 of the sky), satisfying the demand for 8 h of tracking. This system is suitable for building integration because it has a compact and flat shape. The sun position sensor consists of photodiodes and a fiber array in the shape of a cross. The sun position sensor can directly measure the high flux density of the focus (2500 suns). A series of tests were performed using a lux meter and spectrometer to investigate the photometric characteristics of the system for a lightless underpass of 8.6 m x 4.2 m x 2.3 m. The experiments show that the transfer efficiency of this system can reach 25% (with a 10-m long fiber). The luminous efficacy can reach 250 lum/W, which is two times than that of natural light because the fiber can filter out infrared light. The experiments also verified the feasibility of the daylighting system using the parallel mechanism and a direct detection device for highly concentrated light. (C) 2015 Elsevier Ltd. All rights reserved.

A new single-axis solar tracking device is designed and explored, which is able to lift and lower the photovoltaic panels. The photovoltaic panels can be tilted to east-west directions in the process of tracking the sun. In windy weather, the solar panels can be placed close to horizontal rail by using stent, which can minimize the frontal area. What's more, the mechanical strength of this device is better than traditional single-axis solar tracking system, so as to enhance wind resistance in windy weather. The device in this paper is suitable for PV power plants on building roofs because it can meet the strict requirements of wind resistance capacity and safety.

A daylighting system consisting of optical fibers and a sun-tracking model has been developed. The system has a concentrating level of 2500 suns and a tracking precision of better than 0.10 to ensure that the amount of overlap of the focal spot and the entrance face is greater than 80%. The device includes two feedback circles, coarse and fine adjustments, using an angle encoder and a special photodiode array, respectively. The coarse adjustment process relies on predictable a priori information of the sun's trajectory, and discrete features of the output signals from the photodiode array are used by the control program for the fine adjustment. The system then operates in a predictive control mode and exhibits good tracking performance. The optical transmission efficiency is maintained between 37% and 40%, which is close to the theoretical maximum value of 42%. The fluctuation range of illuminance on the working face is less than 20%, which meets visual demands. Five lenses (100 mm in diameter) and five 10-m, 2-mm-diameter plastic optical fibers can provide an illumination of 26.71x for an underpass (4.6 m x 4.2 m) 10 m away. Of a direct normal irradiance of 514 W/m(2), about 70% of the light illuminates the floor. (C) 2014 Elsevier Ltd. All rights reserved.

Solar aided coal-fired power plants utilize solar thermal energy for coupling coal-fired power plants in various types by using the characteristics of different thermal needs of the plants. In this way, the costly thermal storage system and power generating system will be unnecessary while the intermittent and unsteady of power generation will be avoided. Moreover, the aim of large-scale utilization of solar thermal power and the energy-saving will be realized. With the deep analysis of solar aided coal-fired power plants, the contribution evaluating system of solar thermal power needs to be explored. Five common evaluation methods of solar contribution are analyzed in this paper, and a 600MW solar aided coal-fired power plant is studied by these five methods comparatively. Therefore this study will supply the theoretical reference for the future research of evaluation methods and the subsidy policy of new energy.

In this paper, a dual-axis tracking trough solar collector system is established, and used to measure and calibrate flow rate at different conditions by using the ultrasonic flow meter and mass flow meter, providing important reference for follow-up experimental study. With the changing of the medium's temperature and the rotation speed variation of the pump, the two flow meters were used to work together to measure the accurate flow measurements, obtaining the measurement error of the mass flow meter. After that, the reason of error and methods used to reduce the error are analyzed.

This paper investigates a high precision tracking system that adopts the coordinate calculation algorithm and a photosensitive sensor. This system is designed to satisfy the precision requirement in sun tracking for a concentrated sunlight transmitting system via optical fibers. This system is based on a two-stage tracking process, which consists of a coarse adjustment based on the coordinate calculation algorithm and a fine adjustment using a specially designed photosensitive sensor. The core of the photosensitive sensor is a photodiode matrix that could exactly detect the position of the sunlight focal spot via lens focusing. A predictive control process based on the running trend of sun traces will begin once the fine adjustment is completed. The tracking process is steady and accurate because of the predictability of sun traces based on the coordinate calculation algorithm and the acuteness of the photodiode matrix. The highest tracking precision depends on the compactness of the photodiode matrix and has no limits in the accuracy of the coordinate calculation algorithm. The proposed system can track the sun's focal spot with a position precision of less than 0.3 mm, which is the space between the adjacent photodiodes. The tracking angle precision is determined by the ratio of the position resolution of the photodiode matrix to the focal length, and reaches 0.1 degrees. (C) 2013 Elsevier Ltd. All rights reserved.

This paper mainly focuses on the utilization of reversible carbonation reaction of CaO to capture \(\text{CO}_{2}\) from the flue gas. The operating analysis regarding the effects of superficial gas velocity, the particle diameter and the calcination/carbonation cycle number on the carbonation process has been performed and compared to experimental data. It is concluded that in order to optimize the carbonation process the superficial gas velocity can decrease gradually during the reaction and smaller-sized absorbent should be chosen. However, the limits of superficial gas velocity and absorbent size need to be taken into consideration as well to avoid entrainment.

Solar aided coal-fired power plants utilize various types of solar thermal energy for coupling coal-fired power plants by using the characteristics of various thermal needs of the plants. In this way, the costly thermal storage system and power generating system will be unnecessary while the intermittent and unsteady way of power generation will be avoided. Moreover, the large-scale utilization of solar thermal power and the energy-saving aim of power plants will be realized. The contribution evaluating system of solar thermal power needs to be explored. This paper deals with the evaluation method of solar contribution based on the second law of thermodynamics and the principle of thermoeconomics with a case of 600 MW solar aided coal-fired power plant. In this study, the feasibility of the method has been carried out. The contribution of this paper is not only to determine the proportion of solar energy in overall electric power, but also to assign the individual cost components involving solar energy. Therefore, this study will supply the theoretical reference for the future research of evaluation methods and new energy resource subsidy.

A solar-aided coal-fired power plant realizes the integration of a fossil fuel (coal or gas) and clean energy (solar). In this paper, a conventional 600 MW coal-fired power plant and a 600 MW solar-aided coal-fired power plant have been taken as the study case to understand the merits of solar-aided power generation (SAPG) technology. The plants in the case study have been analyzed by using the First and Second Laws of Thermodynamics principles. The solar irradiation and load ratio have been considered in the analysis. We conclude that if the solar irradiation was 925 W/m(2) and load ratio of the SAPG plant was 100%, the exergy efficiency would be 44.54% and the energy efficiency of the plant (46.35%). It was found that in the SAPG plant the largest exergy loss was from the boiler, which accounted for about 76.74% of the total loss. When the load ratio of the unit remains at 100%, and the solar irradiation varies from 500 W/m(2) to 1,100 W/m(2), the coal savings would be in the range of 8.6 g/kWh to 15.8 g/kWh. If the solar irradiation were kept at 925 W/m(2) while the load ratio of the plant changed from 30% to 100%, the coal savings could be in the range of 11.99 g/kWh to 13.75 g/kWh.