摘要
地埋管热泵技术因其显著的节能和环保优势,越来越受到人们的关注,其有效结合了热泵系统、地埋管换热系统和采暖空调系统,冬季从土壤中吸收热量同时蓄存冷量以备夏用,夏季向土壤中释放热量同时蓄存热量以备冬用,其他季节土壤自然恢复,实现了能量的移季利用,是二十一世纪解决能源危机,实现可持续发展战略的绿色空调系统。
本文在国家建设节能型农村政策的影响下,提出了一种适用于广阔地域的具有新型埋管型式的系统——单排地埋管热泵系统。与常见的单管型式相比,它具有较大的容量,能够承担较大的建筑负荷;与管群相比,它的地下土壤温度场具有较好的恢复性能。为了研究该系统在严寒地区的可行性,本文采用FLUENT数值模拟软件对该系统进行了长期的仿真模拟。首先选取哈尔滨地区的某一独立住宅建筑,建立系统各部分的数学模型,包括供暖房间、热泵机组、风机盘管、地埋管换热器及周围土壤的数学模型和相应的定解条件。根据仿真数据和模拟图表,对系统运行一年和多年的土壤温度场变化规律进行研究,分析土壤的热平衡特性和系统的运行特性。为了研究系统的取热蓄热特性和土壤温度场的变化,分别从埋管的总取热量、单位埋深的取热量、热泵COP等方面进行了理论分析。
最后,针对理论分析结果,做出单排地埋管热泵系统在严寒地区的可行性判定,提出相应的改进措施。同时选取北京和武汉两个代表性的城市,根据气候和地质条件的不同对系统进行类比模拟分析,进而指出单排地埋管热泵系统的适用地区,为单排地埋管热泵技术的推广和应用提供理论指导。
单排地埋管热泵系统在严寒地区应用时由于冬夏季负荷不平衡,土壤热源平均温度逐渐下降,热泵和系统的性能降低,对系统长期运行工况不利。然而如果采取相应的热量补偿措施,从系统初投资和运行费用方面考虑单排地埋管热泵系统节能效果显著,发展前景广阔。
Ground-coupled heat pump technology has been gaining increasing popularity in residential and commercial buildings, since it is environment-friendly, causing less energy than their conventional alternatives. The ground source heat pump system effectively combines heat pump system with heating and air-conditioning system, besides it utilizes the earth as heat source. When it runs, the heat exchangers extract or inject thermal energy from or into the ground so that it realizes the seasonal energy diversion. The ground source heat pump system is one of green air-conditioning systems in the 21th century.
With the national policy of building new energy-efficient village, the ground source heat pump with new pipe columns called single-row ground source heat pump has been put forward in this paper. Compared to single-tube ground source heat pump, it has a greater capacity to undertake larger heat or cold loads. It is appropriate to apply in vast area, and the soil temperature field has a better recovery performance, which is superior to tube group type.
The certain building mentioned in the article was selected in Harbin suburb in order to validate the feasibility of this type of system in severe cold area. Long-term numerical simulation of this system was carried out by FLUENT software. We established the mathematical model of each subsystem, containing the physical and mathematical model of heat exchanger, heat pump units, target room and fan coil system, single-value conditions as well. According to the first year’s and years’simulation results of this system, we got the thermal equilibrium analysis of soil field by theoretical analysis of total and unit heat extraction capacity, COP of heat pump, etc.
Then we made the judgment of the feasibility of single-row ground source heat pump system applied in cold area, and then the relevant improvement measures were presented. On the other hand, analogy simulations were performed in typical cities of Beijing and Wuhan and the relevant operation parameters were made according to the different climate and geological conditions. In the end, the applicable area of single-row ground source heat pump came out. All of our research results would provide theoretical guidance for applying and popularizing the technology of this heat pump system.
Because of the imbalance between heat and cooling load in severe cold area, the average soil temperature gradually decreases and the performance of heat pump units and the whole system also become lower as time goes, all of which is unfavorable for the system’s long-term use. While if appropriate measures to compensate for the heat imbalance were took, from initial investment and operational costs, the single-row ground source heat pump system would have significant friendly environmental effects and bright development prospects.
引文
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