【作者】 任承钦；

【导师】 汤广发；

【作者基本信息】 湖南大学 ， 供热、供燃气、通风及空调工程， 2001， 博士

【摘要】 本文系统地总结分析了蒸发冷却空调的应用与技术现状，创新性地提出 了对蒸发冷却过程进行（火用）分析研究。板式换热器是间接蒸发冷却中的中重要 设备，本文提出了-一种隔板为六边形的准逆流板式换热器的设想。采用三维 流动与换热的数值计算方法对换热器内传热过程的影响因素和机理进行了 模拟研究。在第二章，基于（火用）分析基本理论及空凋系统特点，分析研究了合 理的环境状态选择方法及（火用）分析在空调中的应用原则。建立了（火用）效率与（火用） 效比的分析评价指标。 第三章对蒸发冷却过程能量及有用能转换关系进行了研究，阐明了湿空 气（火用）作为蒸发冷却潜力的合理性，对蒸发冷却方案的（火用）分析评价指出了各种 蒸发冷却方式的适用性与合理的使用原则以及提高蒸发冷却过程有用能利 用率的发展方向。 第四章针对蒸发冷却过程中饱和湿空气比热容随温度的非线性变化关 系，研究了非平衡流逆流间接蒸发冷却过程（火用）损失及最佳热容量比的计算线 图。 第五、六章对六边形准逆流换热器中对流、导热甚至传质相互耦合的传 热过程建立了相应的数学物理模型及数值格式。以数据结点及指针链接的图 结构方式建立了模拟对象及网格与内存数据之间的对应关系，适用于几何相 似比发生变化时的网格自动生成，为换热器的模拟分析提供了基础。 第七章提出了对流扩散问题中的广义熵概念，研究了扩散熵产非负性特 征与数值格式稳定性的内在联系，分析证明了扩散熵产非负定性及统计非负 定性的稳定性准则，探讨了稳定性与仿真性之间的矛盾与联系。在尽可能满 足对流扩散过程数值格式中的输运性或守恒性及稳定性的同时，以扩散熵产 仿真为原则的伪扩散系数可有效地提高数值模拟的仿真性，为数值计算中扩 散系数的修正提供了一种有效的手段。 第八、九章对数值格式的有效性进行了实验验证。通过模拟研究分析了 换热器内流场结构与温度场、漩涡的形成机理与特征，强化传热作用及回流 损失。建立了换热器效能准则关联式。更多还原

【Abstract】 Exergy analysis is applied on evaporative cooling. A quasi-counterflowPlate heat exchanger with hexagonal dividing plates is proposed for indirectheat exchange and evaporative cooling. Numerical simulation is used toanalyze three-dimensional flow and heat transfer processes.In Chapter 2, research on principles of exergy anaIysis in air-conditioninglead to a new selection of dead-state and proper evaluation of air-conditioningprocess with exergy effectiveness and exergy efficiency ratio.The conversion of available energy in different evaporative coolingprocesses is analyzed and evaluated in Chapter 3. As results, exergy of moistair is suggested to be evaporative cooling potential and regenerativeevaPorative cooling will be most potential in effectively utilizing the availableenergy.ln ChaPter 4, imbalanced counterflow of indirect evaPorative cooling issimulated while taking into account the non-linearity of the saturation line ofmoist air. Four diagrams are provided to assist in determination of theoptimum heat caPacity ratio.Chapter 5 and ChaPter 6 deal with the physical and mathematical modelfor the proposed heat exchanger. Numerical schemes are discussed in detail. AproPbr data structure is used to assist grid generation for different geometricdimensions.A concept of entropy in broad sense is proposed for convective-diffusiveproblems in ChaPter 7. It is proved that there is an intrinsic relationshipbetween the stability of the numerical schemes of the convective--diffusivedifferential equations and the non-negative property of the entropy generationcaused by the effective diffusion. Thus, non-negative property is suggested asthe criterion of stability. Furthef, diffusion coefficient is replaced by anartificial one in the finite difference equation to simulate the entropygeneration can improve the accuracy of the numerical analysis.ln Chapter 8 and ChaPter 9, numerical analysis is validated byexperiment. Flow structure and heat transfer is analyzed numerica1ly. Anequation of effectiveness is correlated with heat transfer units, Reynoldsnumber, and geometric ratios.更多还原