隨著緊湊型熱交換器的廣泛使用,許多科研人員已經(jīng)密切關(guān)注著它。在不顯著增加其設(shè)計成本的情況下進(jìn)一步提高緊湊熱轉(zhuǎn)換器效率的方法已得到積極開發(fā),使用扭曲的N瓣管就是其中之一。但是,對于三瓣管和四瓣管的研究通常僅限于以水為工作介質(zhì)的情況,并沒有詳細(xì)分析四瓣管的結(jié)構(gòu)參數(shù)對流動特性和傳熱的影響。因此,這項工作從四瓣管結(jié)構(gòu)特性對流動特性和傳熱的影響方面進(jìn)行了全面的分析。同時,還對三瓣管和四瓣管進(jìn)行了比較。針對超臨界CO2,CH4和水這三種介質(zhì),研究人員研究了運行條件對流動特性和傳熱特性的影響。首先,使用ANSUYS FLUENT軟件包,使用以下設(shè)置開發(fā)了所考慮橫截面幾何形狀的三維模型:穩(wěn)態(tài)、SST k-ω湍流模型。接下來分析了結(jié)構(gòu)參數(shù)對壓降、傳熱系數(shù)和TPF的影響。結(jié)果表明,管的L/D比和扭曲角α越高,導(dǎo)熱率和壓降就越高。然后通過分析TPF值(與傳統(tǒng)圓管的傳熱效率相比),可以得出最大TPF的計算公式。對于四瓣管:L/D=0.05,α=1.285o;對于三瓣管:L/D=0.05,α=2.57o。之后,對這些橫截面形狀進(jìn)行比較,最終選擇了四瓣管進(jìn)行更深入的研究。其次,分析了運行條件對超臨界CO2,CH4的...

【文章頁數(shù)】：84 頁

【學(xué)位級別】：碩士

【文章目錄】：
摘要
Abstract
Nomenclature
Chapter 1 Introduction
    1.1 Research background, research purpose and significance
    1.2 Literature review
    1.3 Analysis of literature review
Chapter 2 Numerical calculation method
    2.1 Introduction
    2.2 Mathematical approach
        2.2.1 Basic governing equation of viscous flow
        2.2.2 Turbulence models
        2.2.3 Numerical method
    2.3 Numerical model comparison and validation
        2.3.1 Computational methods and models.#.
        2.3.2 Meshing
        2.3.3 Supercritical CO₂ verification
        2.3.4 Supercritical CH₄ verification
    2.4 Water analytical verification
    2.5 Chapter summary
Chapter 3 The study of the influence of tube geometry on the flow and heat transfer characteristics
    3.1 Introduction
    3.2 Geometric model parameters of the lobed tubes
    3.3 Mesh independence test
    3.4 The influence of the structural parameters of the tube on the heat transfercharacteristics of the flow
        3.4.1 L/D ratio influence
        3.4.2 The influence of the tube twisting angle α
    3.5 Chapter summary
Chapter 4 The study of the influence of operational conditions on the flow and heattransfer characteristics
    4.1 Introduction
    4.2 Supercritical CO2

        4.2.1 Mass flow influence
        4.2.2 Inlet temperature influence
    4.3 Supercritical CH₄

        4.3.1 Mass flow influence
        4.3.2 Inlet temperature influence
    4.4 Water
        4.4.1 Mass flow influence
        4.4.2 Inlet temperature influence
    4.5 Development of correlation equations
    4.6 Chapter summary
結(jié)論
Conclusions
References
Acknowledgement



本文編號：4052822

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