提取冷水凝固热热泵系统的研究

发布时间：2018-07-22 12:07

【摘要】：当前我国建筑供热依旧是以燃煤为主,开发利用低品位可再生清洁能源前景广阔,是当今能源、建筑和环境可持续发展的必然要求。热泵系统具有高效节能和环保效益显著的特点,但是各种热源的问题一直限制了热泵系统的应用。当前水源热泵系统主要是提取环境水源中的显热,但是一直忽略了水凝固所释放出的巨大热量。本文提出一种基于人工热源的提取冷水凝固热热泵系统,并对系统形式、凝固换热特性、系统运行效率、运行能耗与经济性进行了深入研究。首先,提出了提取冷水凝固热热泵系统的系统形式,详细阐述系统结构、运行原理及系统特点,并对系统中的关键问题进行分析。系统的关键性问题主要集中在凝固换热与除冰方面。系统采用液固流化床除冰设备,通过固体颗粒频繁碰撞去除换热器壁面冰层;采用大口径的换热管束,使得固体颗粒对换热器壁面有足够的正向冲击力。此外对于系统的融冰方法,对比分析了开式冷却塔与闭式冷却塔的优缺点,分析结果表明,采用开式冷却塔更能有效融解人工热源中所储存的的冰。其次,在理论分析方面,研究了管内凝固换热特性,并在做出适当的简化及假设后,建立了管内凝固特性与换热特性的物理模型,推导出其数学表达。定义了凝固当量换热系数比Kh来表征凝固换热比对流换热的强化程度。通过数学分析软件,得到管内凝固换热的规律,并对之后的实验研究提供了理论依据。然后,为了研究系统的实际运行效果,搭建提取冷水凝固热泵系统的实验台。实验研究表明,液固流化床除冰系统能够有效去除凝固换热器管壁上的冰层,但是其运行不稳定;凝固换热条件发生的最佳工况为防冻液出口温度在-3~-5℃之间,也就是-4℃左右,此时系统凝固换热量最大,系统能够长时间稳定运行,此时系统最佳工况下的COP为2.9,热泵系统仍然具有一定的节能效果。最后,对提取冷水凝固热热泵系统的机组及系统的能耗进行评价分析,分析结果表明,与燃煤锅炉相比,系统运行能耗降低52.1%。然后通过将系统经济性评价划分为前期初投资与后期系统运行费用两部分,以费用年值为依据进行分析,与其他供热方式进行对比,分析结果表明,系统具有很好的经济性。
[Abstract]:At present, building heating in our country is still mainly coal burning, and the development and utilization of low-grade renewable clean energy have broad prospects, which is the inevitable requirement for the sustainable development of energy, architecture and environment. Heat pump system has the characteristics of high efficiency, energy saving and environmental protection benefit, but the application of heat pump system is limited by various heat sources. The current water source heat pump system is mainly used to extract sensible heat from environmental water source, but it ignores the huge heat released by water solidification. In this paper, a cold water condensing heat pump system based on artificial heat source is proposed. The system form, solidification heat transfer characteristics, system operation efficiency, operation energy consumption and economy are studied deeply. Firstly, the system form of extracting cold water solidified heat pump system is put forward, the system structure, operation principle and system characteristics are described in detail, and the key problems in the system are analyzed. The key problems of the system mainly focus on solidification heat transfer and deicing. The system adopts liquid-solid fluidized bed deicing equipment to remove the ice layer of heat exchanger wall through frequent collision of solid particles, and adopts large-caliber heat transfer tube bundle to make solid particles have enough positive impact force on the wall of heat exchanger. In addition, the advantages and disadvantages of open cooling tower and closed cooling tower are compared and analyzed. The results show that the open cooling tower can effectively melt the ice stored in artificial heat source. Secondly, in the theoretical analysis, the characteristics of solidification heat transfer in the tube are studied, and after making appropriate simplification and hypothesis, the physical model of the solidification and heat transfer characteristics in the tube is established, and its mathematical expression is deduced. The ratio of equivalent heat transfer coefficient Kh to Kh is defined to characterize the strengthening degree of convection heat transfer in solidification ratio. The law of solidification heat transfer in pipe is obtained by mathematical analysis software, and the theoretical basis for later experimental research is provided. Then, in order to study the actual operation effect of the system, an experimental platform for extracting cold water solidified heat pump system was built. The experimental results show that the liquid-solid fluidized bed deicing system can effectively remove the ice layer on the tube wall of solidified heat exchanger, but its operation is unstable. At about -4 鈩，

本文编号：2137414