【作者】 杜顺祥；

【导师】 杜垲；

【作者基本信息】 东南大学 ， 制冷与低温工程， 2006， 硕士

【摘要】 面临全球能源和环境问题的困扰,吸收式制冷在利用工业余热,且对环境影响中占据了优势。传统的氨水吸收式制冷机,存在着系统中设备多,体积大,钢材消耗量大,制冷循环COP值较低等缺点。为了克服氨水吸收式制冷系统的缺点,提高其COP值,本文提出了对吸收器施加一磁场,通过磁场对氨水溶液物性的改变及对吸收过程的影响,提高吸收器的吸收效率,进而达到减小吸收器体积的目的。主要工作如下:1)在气液界面传质的经典模型的基础上,根据试验条件完善了三膜模型,将气液界面分为气相膜层,界面阻力膜层,液相膜层。在吸收气体为纯净氨气时,理想化地忽略了气相传质阻力,提出磁场影响下化学势变化,将界面阻力和液相阻力进行了分析和比较。2)分析了氨水降膜流动的流动特性,传热特性,传质特性和动量,热量,质量的耦合关系,在对实际的氨水降膜吸收过程进行简化假设下,提出了磁场强化氨水吸收的数学模型。考虑到求解区域的不规则,引入了流函数,进行变量代换,使得求解区域规则化,然后采用乘方定律对方程进行离散化求解。根据求解结果,对氨水吸收过程中的各个参数在磁场作用下的变化趋势以及其它因素对吸收效果的影响进行了分析,得出了磁场在一定程度上增强了氨气吸收的结论。3)分析了氨水溶液磁化的机理,以场协同和非平衡热力学的观点对磁场的作用进行了分析,认为磁场能够和浓度场,速度场和温度场协同起来促进氨气吸收。对磁场磁化后的氨水溶液的表面张力,粘度和溶解度进行了微观分析,了解其性质的变化对氨水吸收氨气的过程的影响。4)实验方面包括设计磁场强化氨水吸收实验流程,各个实验设备的结构设计和理论计算,试验关键参数的测量与采集,以及搭建试验台的实际问题。考虑到磁场对氨水吸收过程的两方面的影响,确定了实验目的和步骤,确保能够了解各个因素对吸收过程的改变。更多还原

【Abstract】 Due to the global energy sources and environmental problems, absorption refrigeration system has much more superiority in the use of industrial waste heat. However the COP of conventional ammonia-water absorption refrigeration system is relatively smaller because of its more equipments, large volume and more steel consumption. For the sake of overcoming the defect of the ammonia-water absorption refrigeration system and improve its COP, in this thesis we put forward to put a magnetic field on the absorber. The magnetic field affects the physical property of ammonia solution and the absorption process, which enhances the absorption efficiency of the absorber and achieves the purpose of reducing the size of absorber. The main works are as follows:1) The three-film model is perfected in the basis of experimentation condition and the classical models of gas-liquid inter-phase mass transfer. The model divides the gas-liquid inter-phase into three parts: gas film, interfacial resistance film, liquid film. The gas mass transfer resistance is ignored idealistically because of pure ammonia air; the interfacial resistance and liquid resistance are analyzed and compared.2) The characteristic of flow, heat transfer, mass transfer in the flow of aqueous ammonia falling down the vertical tube and the coupling of momentum, heat and mass is realized. After simplified the real process, the mathematical model of magnetic field promoting the absorption of ammonia is put forward. Considering the abnormity of the physics district, stream function is imported and variable transformed, the equations are dispersed using power law. The change of ammonia absorption process on the magnetic field effect and the absorption efficiency impacted by other factors are analyzed according the result.3) The effect of magnetic filed is analyzed in the point of field coordination and non-equilibrium thermodynamic. The better coordination between the magnetic, concentration, velocity and temperaion fields will lead a higher absorption of ammonia. A microcosmic analysis for the change of the magnetic solution’s surface tension, viscidity and solubility, the effect of physical property on the process of aqueous ammonia absorb ammonia are exposed.4) The experimental facet, including the experiment system of magnetic field promoting the absorption of ammonia, the structure design and theoretic calculation of each experiment equipment, the measure and collection of key parameter. Considering the effect of magnetic field on the absorption process, the purpose and step of experiment do fix on, which make sure comprehend the effect of various factor on the absorption process.更多还原