【作者】 秦娜；

【导师】 赵军；

【作者基本信息】 天津大学 ， 热能工程， 2010， 博士

【摘要】 本文研究了城市原生污水的紊流特性及其利用热泵系统的关键技术问题和解决方法。城市污水是热泵系统理想的冷、热源之一,论文评述了城市污水的热能特征及其热泵系统的效益,主要综述了国内外原生污水源的工程应用及研究现状,包括防阻设备、换热、系统的研究进展,指出了目前存在的问题和研究方向,以推动原生污水热泵系统的广泛应用。在城市原生污水的热能利用中,其流动特性是急需解决的问题之一。原生污水由于固体微粒的存在,使得原生污水流动成为一典型的固液两相流问题。目前的分析法主要为固液两相流模型和非牛顿流体模型。论文在普朗特混合长度理论的基础上,求解了有固体微粒存在的原生污水管内紊流问题,并且又从非牛顿流体的角度推导了有气体存在时的管道内阻力计算关系式,并探讨了阻力变化规律,其目的是为原生污水的一些管道和换热器设计提供理论指导。城市原生污水源热泵普遍采用的提取污水能量的方式都是以间接式为主,也就是在机组前面设置一个换热器,这主要是考虑到污水的水质容易造成堵塞、腐蚀、结垢等,壁面造成对机组的损害,导致系统无法工作。因此在间接式的系统中,污水换热器的性能就显得尤为重要。论文设计了一种流道式换热器的尺寸,根据选型尺寸和分布参数的特征建立了适于这种换热器的传递函数模型,根据供暖季采集到的数据,和动态模型进行了对比验证。设计的流道式换热器应用到了实际工程中,论文根据天津地区的这一实际原生污水源热泵系统,分析了系统的制热工况,并从火用成本角度进行了热经济性评价。结果表明,系统运行的COP为4,实际的运行费用为16.77元/m2,年节省费用约为44.4万元。通过评价结果得知,中介水泵的火用成本比较高,因此论文建立了热泵机组的动态控制模型,提出了变频调节、温度调节和自控调节的控制策略,对原生污水源热泵系统如何更加节能的运行进行了较为系统全面的分析。对于直接换热式系统,研究的难点仍然是污水本身和机组防腐处理,这两者中污水本身的处理效果是占主导地位的。机组中的蒸发器或冷凝器部件的处理也是必要的,但是还需经过大量的实验才好更有把握的用到工程中。为了能够尽快实现直接换热式的系统,论文主要研究了原生污水的处理问题,构思了一级过滤器的结构;设计并制作了二级过滤器即超声波过滤处理装置,并进行了实验;建议在进入机组前增加三级过滤即膜处理装置。通过这三道过滤处理后,原生污水再进入到机组中实现直接式换热,是最合理的。更多还原

【Abstract】 The thesis has researched on the untreated sewage turbulent characteristics and the key technology and solutions of using the untreated sewage in a heat pump system.Urban sewage is a good choice used in the heat pump system as the cold or heat source. The thesis discusses its heat energy characteristics and the benefit of sewage source heat pump systems and summarizes the project application and research approach inside and outside our country from clog-proof equipments, heat exchange type and system performance. The present existing problems are pointed out so as to impel the extensive application of untreated sewage source heat pump systems.The flow characteristics is one of the research focuses when using sewage heat energy. The flow is typical solid-liquid two phase flow for the sewage containing the solid particles. The research method consists of solid-liquid and non-Newtonian models. The thesis researches on the turbulent velocity distribution of untreated sewage based on the Prandtl mixing length concept when the pipe is fully filled, and the resistance calculation correlation using non-Newtonian model when the pipe is filled with some gases. The discussed results of change rules can direct the design of pipe and heat exchanger where the untreated sewage flows.The sewage source heat pumps usually adopt indirect heat exchange pattern because of the clogging or corrosion effect probably damaging the units. Sewage heat exchangers play an important role in the system performance especially when untreated sewage is used as heat or cold source. The thesis designs the dimension and establishes the suitable transfer functions of a free-flow-channel heat exchanger. The models are verified according to the collected data from the real system using the heat exchanger. The thesis studies the practical system in Tianjin and evaluates its performance from the exegetic cost. The system COP is close to 4, the actual working cost is 16.77yuan per square meter and the saving is about 0.44million yuan.The exegetic cost of water pump entering the evaporator show the highest. So the thesis establishes the heat pump dynamic control models and analyzes variable frequency, temperature and self-control modulations how affect the energy saving operation.Coating the unit component and especially treating the sewage are essential for a system of direct heat exchange pattern. The evaporator or condenser treatments are also essential but it needs large quantities of experiments to ensure the practical performance. The thesis studies the first level filter’s configuration, designs and tests a newly equipment as the second level filter which utilizes ultrasonic treatment technique. At last the thesis suggests the film treating technique at the end of the newly equipment. It can make the sewage at the outlet cleaner and safer to enter the unit components.更多还原