本文關(guān)鍵詞：塔式太陽能熱發(fā)電吸熱器蒸發(fā)段沸騰傳熱的數(shù)值模擬　出處：《華北電力大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 太陽能吸熱器 不均勻能流 VOF 多點聚焦

【摘要】：近年來,隨著能源需求的劇烈增長,太陽能熱發(fā)電技術(shù)正成為世界范圍內(nèi)可再生能源領(lǐng)域的熱點。太陽能吸熱器是太陽能熱發(fā)電站中光-熱轉(zhuǎn)換的核心部件,其性能直接影響整個電站的正常運行。吸熱管面向鏡場的半圓周受熱,且熱流密度沿軸向不斷變化,背向鏡場的半圓周絕熱；同時集熱管內(nèi)水-蒸汽工質(zhì)的沸騰流動換熱尤為復(fù)雜,因此研究其受熱特性具有重要意義。本文基于ANSYS FLUENT平臺,數(shù)值計算三維、非穩(wěn)態(tài)的汽液兩相流動。模擬分析結(jié)果呈現(xiàn)了吸熱管管內(nèi)的汽液兩相流動特性,描述了吸熱管軸向方向汽液兩相流的流型演變和速度分布。另一方面,結(jié)果揭示了吸熱管管內(nèi)工質(zhì)和管壁的熱特性。沿軸向方向,工質(zhì)不斷受熱,溫度逐漸升高至飽和溫度373 K。吸熱管管壁溫度在軸向和周向方向溫度分布極不均勻,與管壁受熱側(cè)表面能流密度分布有很大的相關(guān)性。最大壁溫和管道橫截面最大溫差均出現(xiàn)在Z=1000mm的吸熱管管道截面。吸熱管軸向的Nu數(shù)與管內(nèi)汽液兩相流流型密切相關(guān),在泡狀流階段達(dá)到最大值。進(jìn)一步,文章分析了吸熱管三個方向(軸向、軸向、徑向)的溫度梯度變化和最大絕對溫度梯度。該文分析結(jié)果有助于深入了解塔式電站吸熱器吸熱管的整體性能。塔式太陽能熱發(fā)電站定日鏡場通常采用多點聚焦策略來降低吸熱器表面輻射能流的不均勻性,防止發(fā)生過熱故障。本文以塔式電站柱式吸熱器單根吸熱管為研究對象,采用具有多個極大值的高斯函數(shù)來描述多點聚焦時吸熱管表面具有多個能流集中點的輻射能流分布,數(shù)值模擬分析吸熱管的熱參數(shù)特性。結(jié)果顯示：聚焦點個數(shù)一定時,存在最優(yōu)的聚焦點位置,使得吸熱管表面輻射能流不均勻性最低。同時隨著聚焦點個數(shù)增加,吸熱管表面輻射能流更加均勻,最大壁溫減小,而軸向最大絕對溫度梯度增大。因此對于多點聚焦,應(yīng)綜合考慮吸熱管的熱參數(shù),選擇最優(yōu)化的聚焦點個數(shù)和聚焦點位置。
[Abstract]:In recent years, with the rapid growth of energy demand, solar thermal power generation technology is becoming a worldwide hot spot in the field of renewable energy. Solar energy absorber is the core component of photothermal conversion in solar thermal power plants. Its performance directly affects the normal operation of the whole power station. The heat flux of the endothermic tube is heated on the semi-circular circle of the mirror field, and the heat flux is constantly changing along the axial direction, and the semi-circular circumferential adiabatic heat of the backmirror field is obtained. At the same time, the boiling heat transfer of water-steam working fluid in the collector pipe is very complicated, so it is of great significance to study its heating characteristics. Based on the ANSYS FLUENT platform, the three-dimensional numerical calculation is carried out in this paper. The simulation results show the characteristics of vapor-liquid two-phase flow in an endothermic pipe, and describe the evolution and velocity distribution of the gas-liquid two-phase flow in the axial direction of an endothermic tube. The results reveal the thermal characteristics of the working fluid and the tube wall in the endothermic pipe, and the working fluid is continuously heated along the axial direction. The temperature gradually rises to the saturation temperature 373 K. the temperature distribution of the endothermic tube wall in the axial and circumferential directions is extremely uneven. The maximum temperature difference of the cross section of the maximum wall and pipe appears in the section of the endothermic pipe with Z1000 mm. The number of Nu in the axial direction of the endothermic pipe and the steam in the tube are closely related to the distribution of the energy flow density on the surface of the heated side of the tube wall. The flow pattern of liquid two-phase flow is closely related. In the bubbly flow stage, the maximum value is reached. Further, the three directions (axial, axial) of the endothermic tube are analyzed. Radial). The results of this paper are helpful to understand the whole performance of the absorber tube of tower type power station. The multi-point focusing strategy is usually used in the helioscope field of tower solar thermal power station. Reduce the non-uniformity of radiation energy flow on the surface of heat absorber. In this paper, the single tube of column absorber of tower power station is taken as the research object. The Gao Si function with multiple maximums is used to describe the radiation energy flow distribution on the surface of endothermic tube with multiple energy flow concentration points. The numerical simulation results show that there is an optimal focal point position when the number of focal points is fixed. At the same time, with the increase of the number of focal points, the radiation energy flow on the surface of the endothermic pipe is more uniform, and the maximum wall temperature decreases. The axial maximum absolute temperature gradient is increased. Therefore, the heat parameters of endothermic pipe should be considered synthetically, and the optimum number of focal points and the location of focal point should be selected for multi-point focusing.
【學(xué)位授予單位】：華北電力大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TM615

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本文編號：1412686