土壤—空气换热系统性能及能量指标的数值模拟分析研究

发布时间：2018-04-20 05:15

本文选题：土壤-空气 + 换热器　；参考：《西安建筑科技大学》2017年硕士论文

【摘要】：随着国家经济的迅速发展,我国的建筑能耗也在逐年增加,其中为保障建筑舒适性的供热、制冷能耗占据建筑能耗的主要部分。建筑能耗的来源主要依靠化石燃料的燃烧,会增加温室气体的排放以及造成环境的破坏;而加大自然能源的使用,如太阳能、风能、生物能以及地热能等,能够在降低能耗的同时减少对环境的破坏。地表浅层土壤是一个天然的冷热源,在夏季可以作为冷源为建筑提供冷量,在冬季可以作为热源为建筑提供所需热量,具有巨大的利用价值。土壤-空气换热系统是一种利用浅层土壤的蓄热蓄冷能力来获取能量满足建筑制冷供热需求的有效被动式节能方式。本课题以理想换热模型为基础对换热器的性能进行了综合分析,在此基础上建立更为复杂精准的土壤空气三维耦合换热模型,对换热系统应用于长沙地区的全年能量收益进行了预测。本文首先介绍了土壤-空气换热系统的基本工作原理,同时对影响系统运行性能的管径、流速、管长、埋深、空气相对湿度以及土壤热物理性质等相关参数进行了简单的分析。在此基础上建立了土壤-空气换热系统物理模型以及数学模型,并对模型的初始条件以及边界条件进行了定义。然后,以印度Bisoniya的研究为基础,建立不考虑土壤温度场的理想换热器模型,分析了换热器管径、管长以及流速对换热效率的影响。发现在一定管径和流速下,换热器管道长度具有一定的阈值,并综合分析了不同管径和流速下的推荐管长。同时,采用三维土壤空气耦合模型分析了系统运行对土壤温度场的影响,提出了全天六小时运行停运两小时的间歇性运行策略。最后,以典型的夏热冬冷长沙地区作为研究地点,以月作为研究单位,通过数值模拟分析,预测了一个有效管长30m,埋深4m,管径200mm,风速为5m/s的土壤空气换热系统全年能量收益为4636kWh。通过计算研究得到,系统能量回收时间短、季节能效比高,具有广泛的应用前景。通过对土壤空气换热系统的分析研究可以看出,土壤空气换热系统具有十分可观节能前景,能够很好的适应夏热冬冷地区的气候环境。
[Abstract]:With the rapid development of national economy, the building energy consumption of our country is increasing year by year. In order to ensure the heating of building comfort, refrigeration energy consumption occupies the main part of building energy consumption. The source of building energy consumption mainly depends on the burning of fossil fuels, which will increase greenhouse gas emissions and damage the environment; and increase the use of natural energy, such as solar, wind, bio-energy and geothermal energy, etc. Can reduce energy consumption while reducing the damage to the environment. Surface shallow soil is a natural source of cold and heat, which can be used as a cold source for buildings in summer and as a heat source for buildings in winter. The soil-air heat transfer system is an effective passive energy saving method which uses the heat storage capacity of shallow soil to obtain energy to meet the needs of building refrigeration and heating. Based on the ideal heat transfer model, the performance of the heat exchanger is comprehensively analyzed, and a more complex and accurate three-dimensional coupled heat transfer model of soil and air is established. The annual energy return of heat transfer system applied in Changsha area is predicted. In this paper, the basic working principle of soil-air heat transfer system is introduced, and the parameters such as pipe diameter, velocity, pipe length, buried depth, air relative humidity and soil thermophysical properties, which affect the operation performance of the system, are simply analyzed in this paper. On this basis, the physical model and mathematical model of soil-air heat transfer system are established, and the initial conditions and boundary conditions of the model are defined. Then, based on the research of Bisoniya in India, an ideal heat exchanger model without considering soil temperature field is established, and the effects of tube diameter, tube length and flow rate on heat transfer efficiency are analyzed. It is found that the tube length of heat exchanger has a certain threshold under certain tube diameter and flow rate, and the recommended tube length under different tube diameter and velocity is analyzed synthetically. At the same time, the effect of system operation on soil temperature field was analyzed by using a three dimensional soil air coupling model, and an intermittent operation strategy was put forward in which the operation was suspended for two hours and six hours a day. Finally, with typical hot summer and cold winter Changsha area as the research site and the month as the research unit, the annual energy income of a soil air heat transfer system with effective pipe length of 30 m, buried depth of 4 m, pipe diameter of 200 mm and wind speed of 5m/s is predicted to be 4636kWh. The calculation results show that the energy recovery time of the system is short and the seasonal energy efficiency ratio is high. Through the analysis of the soil air heat transfer system, it can be seen that the soil air heat transfer system has a great prospect of energy saving and can adapt to the climate environment in the hot summer and cold winter area.
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU83

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