本文關鍵詞： Super ORV 相變傳熱 數(shù)值模擬 優(yōu)化　出處：《華南理工大學》2015年碩士論文　論文類型：學位論文

【摘要】：隨著能源危機和環(huán)境問題日益嚴峻,液化天然氣(Liquefied Natural Gas,簡稱LNG)作為一種清潔高熱值能源備受關注,天然氣工業(yè)的發(fā)展已成為改善能源結構、推動低碳經(jīng)濟發(fā)展的重要力量。在實際應用中,液化天然氣需要氣化并加熱到常溫才能使用,因而LNG氣化器成為天然氣工業(yè)中必不可少的核心設備。目前,我國用于基本負荷型LNG接收站的開架式氣化器設備主要依賴國外進口。LNG產(chǎn)業(yè)快速發(fā)展與LNG接受終端再氣化技術受限的矛盾越來越突出,對超級開架式氣化器(Super Open Rack Vaporizer,簡稱Super ORV)的國產(chǎn)化提出了強烈的要求。本論文分析了前人關于Super ORV的研究狀況,并設計了一種與新型開架式內(nèi)螺旋氣化器配套的氣化內(nèi)管,對其傳熱傳質特性進行了研究。本論文首先根據(jù)不同的混合規(guī)則對液化天然氣(LNG)和氣態(tài)天然氣(NG)熱物性進行計算。通過計算得到了LNG泡點溫度隨壓力的變化曲線圖以及LNG和NG密度、定壓比熱容、導熱系數(shù)、動力粘度隨溫度的變化曲線圖。分析了Super ORV的傳熱過程:預熱過程、氣化過程、加熱過程。并對每一個過程的傳熱計算進行了總結。建立了Super ORV氣化段的物理模型和數(shù)值模型。其中,數(shù)值模型包括:Mixture多相流模型、湍流模型、相變模型以及自定義相變傳熱傳質函數(shù)(UDF)。應用FLUENT流體力學軟件模擬了兩種氣化管的流動和傳熱特性,分析了兩種氣化管速度場、溫度場和截面含氣率分布情況。結果表明:螺旋氣化管截面有顯著垂直于主流方向的二次流;入口速度0.91m/s時,螺旋管出口氣相含量比光滑管高6.1%;入口速度在0.91 m/s增加到1.63 m/s的流量范圍內(nèi),傳熱強化綜合性能評價因子η皆大于1,螺紋管傳熱強化效果明顯;隨著LNG入口流速的增大傳熱綜合性能評價因子η也增大。用正交試驗方法對螺紋氣化管進行結構優(yōu)化。根據(jù)正交實驗結果,對壁面平均換熱系數(shù)的影響因素排序為:小徑、螺紋肋寬度、螺距;對管程壓降的影響因素排序為小徑、螺距、螺紋肋寬度。螺紋氣化管最優(yōu)結構方案為:螺旋氣化管的小徑為8 mm、螺旋肋寬度為55°、螺距為120 mm。最后,確定數(shù)值模擬的驗證方法,即通過借助前人實驗研究數(shù)據(jù),在相同的工況下進行數(shù)值模擬,結果表明:模擬值與實驗值誤差在合理范圍內(nèi)。本論文的研究成果不但為Super ORV的開發(fā)提供理論依據(jù),同時為其性能研究與優(yōu)化提供一種合理的研究方法與思路。
[Abstract]:With the increasingly severe energy crisis and environmental problems, LNG (liquefied Natural Gas) as a clean and high calorific energy source has attracted much attention, and the development of natural gas industry has become the improvement of energy structure. In practice, liquefied natural gas needs to be gasified and heated to normal temperature before it can be used, so LNG gasifier has become an essential core equipment in the natural gas industry. The contradiction between the rapid development of imported LNG industry and the limitation of LNG receiving terminal regasification technology is becoming more and more prominent in China, which is mainly used in the open-shelf gasifier equipment for the basic load type LNG receiving station. A strong requirement for the localization of Super Open Rack Vaporizer (Super ORV) for super open-shelf gasifier is put forward. In this paper, the research status of Super ORV is analyzed, and a new type of gasification inner tube is designed to match the new open-shelf internal spiral gasifier. The characteristics of heat and mass transfer are studied in this paper. Firstly, the thermal properties of liquefied natural gas (LNG) and gaseous natural gas (NGG) are calculated according to different mixing rules. The curves of LNG bubble temperature with pressure are obtained by calculation. Graphs and LNG and NG densities, The curves of specific heat capacity, thermal conductivity and dynamic viscosity with temperature at constant pressure are analyzed. The heat transfer process of Super ORV is analyzed: preheating process, gasification process, The heat transfer calculation of each process is summarized. The physical model and numerical model of Super ORV gasification section are established. Phase change model and self-defined phase change heat and mass transfer function are used to simulate the flow and heat transfer characteristics of two kinds of gasification tubes by using FLUENT fluid dynamics software, and the velocity fields of two kinds of gasification tubes are analyzed. The distribution of temperature field and gas content in the section. The results show that there is a significant secondary flow perpendicular to the main stream in the section of the spiral gasification tube, and the inlet velocity is 0.91m / s. The gas phase content at the outlet of the spiral tube is 6.1 higher than that of the smooth tube, and the inlet velocity increases from 0.91 m / s to 1.63 m / s, the evaluation factor 畏 of heat transfer enhancement is all greater than 1, and the heat transfer enhancement effect of the threaded tube is obvious. With the increase of inlet velocity of LNG, the heat transfer evaluation factor 畏 also increases. The structure of threaded gasification tube is optimized by orthogonal test. According to the results of orthogonal experiment, the influence factors of wall average heat transfer coefficient are ranked as small diameter. Thread rib width, pitch, pressure drop of pipe are ranked as small diameter, pitch, thread rib width. The optimum structure scheme of screw gasification pipe is: diameter of helical gasification pipe is 8 mm, width of helical rib is 55 擄, pitch is 120 mm. The verification method of numerical simulation is determined, that is, by means of previous experimental research data, numerical simulation is carried out under the same working conditions. The results show that the error between the simulated value and the experimental value is within a reasonable range. The research results of this paper not only provide a theoretical basis for the development of Super ORV, but also provide a reasonable research method and train of thought for its performance research and optimization.
【學位授予單位】：華南理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TE96;TK124

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