【作者】 牛润萍；

【导师】 由世俊；

【作者基本信息】 天津大学 ， 供热、供燃气、通风及空调工程， 2008， 博士

【摘要】 传统的压缩式制冷空调系统为创造室内舒适的生活和工作环境作出了很大的贡献,但是相应地也带来了一些负面的影响,特别是大大地加重了能源和环境方面的负担。因此,当前研究开发新型节能、环保的空调系统显得尤为紧迫。本文提出了冷凝热再生式溶液除湿空调系统,将传统的压缩式制冷系统与溶液除湿系统相结合,利用溶液除湿,再利用冷凝热实现溶液再生,达到了空调制冷系统节能降耗的目的。对除湿溶液的物理性质进行了研究,结合经济性,给出了除湿溶液的选择原则,确定了氯化锂溶液为本课题的除湿剂。搭建了冷凝热再生式溶液除湿空调系统,采用实验研究和数值模拟的方法对系统两个主要部件——除湿器和再生器的性能进行研究。在实验系统现场测试了叉流除湿器的传热传质性能,得到空气和溶液入口参数对除湿性能的影响关系。采用逐步多元回归方法处理实验数据,给出了除湿器传热传质系数,以及评价除湿器性能指标——除湿效率和除湿量与溶液和空气入口参数的函数关系式,为理论研究和工程应用提供了有益参考。在传热传质理论的基础上,建立了交叉流除湿器内部溶液与空气的热质交换数学模型,通过离散数值求解的方法,得到了描述除湿器内部溶液与空气参数的分布规律,对除湿器性能研究有一定的指导作用。在蒸发式冷凝器盘管表面喷淋稀溶液,利用蒸发冷凝原理实现溶液再生。通过对蒸发式冷凝再生器传热传质性能的实验研究,得到空气、溶液入口参数及制冷剂参数对再生性能的影响规律,并回归得到再生器传热传质系数的经验公式,为设计和优化蒸发式冷凝再生器提供理论依据。建立了蒸发式冷凝再生器热质交换二维数学模型,得到溶液、空气和制冷剂三种流体各参数在再生器内部的二维分布规律。用实验数据验证数学模型,经过比较,发现模拟结果与实验结果吻合较好,表明数学模型可以实现对蒸发式冷凝再生器部件的性能研究。研究结果表明,在夏季新风需要进行除湿处理的空调系统中,采用冷凝热再生式溶液除湿空调技术具有明显的节能效果,蒸发式冷凝再生器的特性对系统性能起着重要的影响作用。更多还原

【Abstract】 Conventional vapour compression refrigeration system is used to create comfortable living and working environment. However, it has adverse impact on energy consumpsion and outdoor environment. High energy consumption and high environmental pollution are two major disadvantages of such system. So it is urgent to develop a kind of air conditioning system with energy-conservation and economized electricity character. Liquid desiccant air conditioning system with condensing heat regeneration was presented in this paper, which integrated vapour compression refrigeration system and liquid desiccant system. The heat rejected from the condenser was used to regenerate the liquid desiccant to improve the performance of system and conserve energy.The thermo-physical properties of liquid desiccant were presented. Combining with economic analysis, the principle of selection of liquid desiccant was provided. And lithium chloride(LiCl)was choused as a desiccant for dehumidification in this paper.Liquid desiccant air conditioning system with condensing heat regeneration was established. This paper presented the experimental tests and the numerical simulation on the main components of system dehumidifier as well as regenerator.Experiment was carried out to test heat and mass transfer performance of cross-flow dehumidifier using metal packing. The effects of air flow rate, solution flow rate and inlet parameters of air and solution on the outlet parameters were also investigated. And a great deal of data obtained from experiment was processed using multiple linear regression method. Several empirical formulas were given, i.e. coefficient of heat and mass transfer, the rates and efficiency of dehumidification evaluating performance of dehumidifier, which provided good reference and necessary information for further theoretical investigation.A mathematical model of cross-flow dehumidifier describing heat and mass transfer between air and liquid desiccant was set up. Taking the heat and mass transfer coefficients achieved from experiments as the input parameter of the model, the parameter distribution of air and liquid desiccant on the packing surface were described, which is of reference and guiding significance to the performance analysis of dehumidifier. Weak solution was sprayed on the tube bundle of evaporative condenser. Liquid solution was regenerated utilizing evaporation condensation mechanism. Performance of evaporative condensing regenerator was studied experimentally. The influences of inlet parameters such as air, solution and refrigerant on the performance of regenerator were discussed. Heat and mass transfer coefficient of regenerator was correlated with air flow rate, solution flow rate, inlet air temperature and inlet solution concentration. The results had great value in the design and improvement of evaporative condensing regenerator.A two dimensional steady state model was developed and solved numerically to predict the performance of evaporative condensing regenerator. Two dimensional parameters distribution of air, solution and refrigerant were calculated by the mathematical model. The experimental results were used to validate mathematical model. It indicated that the simulation results agreed with experimental data well. The results showed that the mathematical model could be used to predict the performance of regenerator.Research results demonstrated that liquid desiccant air conditioning system with condensing heat regeneration had remarkable energy saving effect when it was used to reduce the moisture content of fresh air in summer, and characteristics of evaporative condensing regenerator played an important role in performance of system.更多还原