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定压工况下TS-CAES系统释能过程中射气抽气器工作参数的优化分析

Optimization Analysis of the Operating Parameters of the Ejector Integrated in the Energy Release Process of TS-CAES System under Constant Pressure Conditions

【作者】 王琰

【导师】 卿绍伟;

【作者基本信息】 重庆大学 , 工程(动力工程)(专业学位), 2022, 硕士

【摘要】 为了缓解化石能源的大量使用给环境带来的污染问题,可再生能源的研究和利用得到迅速的发展,但是因其不稳定性、间歇性等特点使得太阳能、风能资源浪费严重,并且影响到电网的稳定和安全,因此需要利用储能技术来解决这一重要问题。压缩空气储能技术是一种可以实现大规模储能的储能技术,具有使用寿命长、安全性高、成本低、响应速度快、不受环境限制等诸多优点。在CAES(压缩空气储能)系统的释能阶段增加射气抽气器已经被认为是提高系统效率的有效途径,但是关于射气抽气器工作参数的优化还缺乏详细的建模和分析。因此,本文针对一个带射气抽气器(即系统I)或不带射气抽气器(即系统II)的10 MW TS-CAES(蓄热式压缩空气储能)系统的热动力学模型,在定压运行时分别考虑了固定第一台膨胀机前定压压力P4、固定第二台膨胀机前定压压力P6两种情况。其中,采用一维半经验模型确定特定工作气体压力Pp、低压气源和恒压运行条件下射气抽气器的最大引射系数wmax。本文的主要研究成果如下:(1)本文针对含射气抽气器的10 MW TS-CAES系统,分析了在P4固定和P6固定两种定压工况下性能参数和工作气体压力Pp之间的变化规律。当P4固定时,wmax与Pp正相关,而总释能时间tI、被卷吸总量me和总输出功EI随着Pp的增加呈现抛物线状变化;而当P6固定时,wmax、me、EI与Pp之间的变化规律不变,但是总释能时间tI保持不变。(2)第一台膨胀机的排气是射气抽气器的最佳低压气源,不同的低压气源使wmax、tI、me和EI发生巨大的变化。不管是定压压力P4固定时还是P6固定时,以第一台膨胀机排气作为低压气源的wmax大约比e=7、9和11的情况下的wmax大一个或几个数量级。因此,以第一台膨胀机排气作为低压气源的情况下的tI、me、EI、和利润明显大于以第二、三、四台膨胀机作为低压气源的情况。(3)对于系统I而言,在P4固定时的大多数定压运行工况下,往返效率的上升幅度(48)和利润与Pp呈正相关;而对于P6固定时的任何时刻,往返效率的上升幅度(48)和利润与Pp呈抛物线型的变化关系。(4)选择定压压力P6固定时的最优(48)、利润均大于P4固定时的数值。当P6固定时,当以第一台膨胀机排气作为低压气源时,Pp=Pp,opt时,当P6从2.4630 MPa下降到1.0441 MPa时,相应的最优(48)约从7.109%增加到17.71%,相应的最优利润约从124美元增加到494美元。当P4固定时,同样以T1排气作为低压气源时,Pp=Pp,opt时,当P4从7 MPa下降到3 MPa时,相应的最优(48)约从2%增加到10%,相应的最优利润约从35美元增加到275美元。(5)针对实际和设计阶段的CAES系统,提出了射气抽气器最佳低压气源的两种确定方法;通过对wmax、tI、me和E的综合分析,提出了射气抽气器最佳Pp的三个确定原则;并且通过对定压压力P4和P6固定两种工况的分析,给出了最佳定压运行工况点的确定方法。

【Abstract】 In order to alleviate the pollution problem brought by the massive use of fossil energy to the environment,the research and utilization of renewable energy has been rapidly developed,but its instability,intermittency and other characteristics make solar and wind energy resources wasted seriously,and affect the stability and security of the power grid,so the need to use energy storage technology to solve this important problem.Compressed air energy storage technology is a kind of energy storage technology that can realize large-scale energy storage,with many advantages such as long service life,high safety,low cost,fast response time,and not subject to environmental restrictions.The addition of ejector in the energy release phase of CAES(compressed air energy storage)systems has been considered as an effective way to improve the system efficiency,but there is a lack of detailed modeling and analysis on the optimization of the jet extractor operating parameters.Therefore,in this paper,for a thermodynamic model of a 10 MW TS-CAES(thermal storage compressed air energy storage)system with ejector(i.e.,System I)or without ejector(i.e.,System II),two cases of fixed first expander front pressure P4 and fixed second expander front pressure P6 are considered for constant pressure operation.In this paper,a one-dimensional semi-empirical model is used to determine the maximum induced coefficient wmax of the ejector for a specific operating gas pressure Pp,a low-pressure gas source and a constant-pressure operation.The main results of this paper are as follows(1)In this paper,the variation law between the performance parameters and the working gas pressure Pp under two fixed pressure conditions,P4 fixed and P6 fixed,is analyzed for a 10 MW TS-CAES system with ejector.When P4 is fixed,wmax is positively correlated with Pp,while the total energy release time t I,the total volume me and the total output work EIshow a parabolic variation with the increase of Pp;while when P6 is fixed,the variation law between wmax,me,EI and Pp remains the same,but the total energy release time t I remains the same.(2)The exhaust of the first expander is the best low-pressure source for the ejector,and the different low-pressure sources make a huge difference in wmax,t I,me and EI.The wmaxwith the first expander exhaust as the low pressure source is approximately one or several orders of magnitude larger than the wmax for e=7,9 and 11,regardless of whether the constant pressure is fixed at P4 or P6.Thus,the t I,me,EI,and profit for the first expander exhaust as the low pressure source are significantly larger than for the second,third,and fourth expander as the low pressure source.(3)For system I,the increase in round-trip efficiency and profit are positively correlated with Pp for most constant pressure operating conditions when P4 is fixed,while the increase in round-trip efficiency and profit are parabolic with Pp for any moment when P6 is fixed.(4)The rise and profit of the optimal when the constant pressure P6 is fixed is chosen to be greater than the value when P4 is fixed.When P6 is fixed,the optimal increases from 7.109%to 17.71%when Pp=Pp,opt and P6 decreases from 2.4630 MPa to1.0441 MPa when the first expander exhaust is used as the low-pressure gas source,and the optimal profit increases from 124$to 494$.When P4is fixed and T1 exhaust is used as the low pressure source,Pp=Pp,opt,when P4 decreases from 7 MPa to 3 MPa,the corresponding optimal increases from 2%to 10%,and the corresponding optimal profit increases from about 35$to 275$.(5)For the actual and design stage CAES systems,two methods for determining the optimal low pressure gas source for the ejector are proposed;three principles for determining the optimal Pp for the ejector are proposed through the comprehensive analysis of wmax,t I,me and E;and the determination of the optimal fixed pressure operating condition point is given through the analysis of the two fixed conditions of the fixed pressure P4 and P6.

  • 【网络出版投稿人】 重庆大学
  • 【网络出版年期】2024年 09期
  • 【分类号】TK02
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