冷却塔复合式地源热泵系统控制策略研究及实现

发布时间：2018-01-08 11:33

本文关键词：冷却塔复合式地源热泵系统控制策略研究及实现　出处：《东华大学》2014年硕士论文　论文类型：学位论文

【摘要】：节能已经成为建筑业每年都要推进的强制性工作。空调系统的节能是建筑节能中一个迫切需要解决的问题。近年来,地源热泵空调系统以其突出的环保和节能特性,得到了广泛的应用。但在系统的实际运行中,当夏季排至土壤中的热量大于冬季从土壤中吸收的热量时,就会产生热堆积效应,使土壤温度逐年升高,与地源热泵系统的换热温差也逐渐偏离稳定数。土壤温度的升高对机组的2和制冷效率都有非常大的影响,因此解决热堆积问题对土壤源热泵系统的正常运行十分关键。冷却塔复合式地源热泵系统即把地源热泵系统与冷却塔结合使用的系统形式,此方法可有效的改善地源热泵系统的运行性能,减少地埋管数量减少占地面积,平衡地埋管选题全年的放热量和吸热量,解决土壤的热积聚问题,使地源热泵系统的优越性能得到充分的发挥。由于冷却塔复合式地源热泵系统组成复杂,人工控制操作误差较大,不能充分发挥冷却塔复合式地源热泵系统节能高效的优势。为了解决目前冷却塔复合式地源热泵系统在运行控制方面存在的问题,本文提出了一种新的冷却塔和地埋管系统复合运行的控制策略,并开发了一套能够有效实现相应控制软件。首先对冷却塔复合式地源热泵系统控制策略进行分析比较。国内外学者对冷却塔复合式地源热泵系统进行了大理的模拟研究,得出了三种常用控制策略：冷却塔开启时间控制、热泵热源侧进(出)口流体最高温度控制、地埋管换热器进(出)水温度与室外空气湿球温度的温差控制。在总结前人的研究成果的基础上,为了充分利用有利的室外空气条件,本文提出了如下控制策略：在制冷季初期和末期冷却塔单独运行,在制冷季中期采用地埋管换热器进(出)水温度与室外空气湿球温度的温差控制方式进行冷却塔和地埋管系统的复合运行。其次对冷却塔的数学模型进行分析。根据Merkel首先建立的冷却塔的热焓平衡方程式,类比于显热换热器的效能-传热单元数法计算公式,利用迭代计算得到的冷却塔出水温度。但结果精度不能满足自动控制系统的要求,因此选用直接影响冷却塔出水温度的室外空气湿球温度作为控制参数。然后在理论研究基础上,本课题组搭建了一个冷却塔复合式地源热泵实验平台。并根据该实验平台昀具体情况,设计了一套以传感器和执行机构为现场元件层、PLC控制器和单回路控制器为控制层、Lab VIEW上位机软件为管理层的三层网络控制方案,对整个控制系统硬件和各控制层之间的数据交换进行整体设计、调试。再次,根据所确定的控制策略和现有实验平台开发了一套可视化程度高、使用方便的冷却塔复合式地源热泵自动控制软件。该软件能对系统的运行参数实时监测;能对系统的运行参数进行设定和调控;能对空调系统温度超限、系统故障进行报警提示;并能将系统数据实时显示、储存及打印。最后,对冷却塔复合式地源热泵自动控制系统的硬件配合和软件控制进行了现场调试和分析,得出该控制系统运行稳定,系统数据的采集、显示、等都运行正常。该系统能根据地埋管出水温度和室外湿球温度的变化自动调节冷却塔和地埋管系统的运行方式,通过设定适当的运行参数,可以是冷却塔和地埋管系统有机的配合运行,有效降低冷却水温度,达到提升机组性能、缓解地下土壤热不平衡的作用。
[Abstract]:Energy saving has become mandatory in architectural industry every year. To promote energy-saving air-conditioning system is an urgent need to address the issue of building energy conservation. In recent years, ground source heat pump air conditioning system with environmental protection and energy saving characteristics of its outstanding, has been widely used. But in the actual operation of the system, when the summer came to the soil heat is greater than that in winter the heat absorbed from the soil, will produce the heat accumulation effect, the soil temperature increased year by year, and the temperature difference of ground source heat pump system also deviates from the stability number. The rise of soil temperature on the unit has a very large impact on 2 and cooling efficiency, so to solve the problem of heat accumulation the normal operation of GSHP system is very important.
The cooling tower HGSHP that GSHP system with cooling tower system combined with the form of use, this method can improve the performance of GSHP system running effectively, reduce the number of buried pipe to reduce the area, balance of heat and heat absorption on buried pipe topics throughout the year, to solve the problem of soil heat accumulation, the superior performance of the ground source the heat pump system into full play.
Because the cooling tower HGSHP complex, manual control error is large, can not give full play to the advantages of the cooling tower HGSHP energy efficient. In order to solve the cooling tower HGSHP in operation control problems, this paper proposes a new operation system of composite pipe cooling tower and ground control strategy, and developed a set of effective realization of the corresponding control software.
The control strategy of the cooling tower HGSHP were analyzed and compared. The domestic and foreign scholars have conducted research on the simulation of cooling tower of Dali HGSHP, obtained three kinds of control strategies: cooling tower opening time control, heat pump side into (out of) the highest temperature is in fluid control, ground heat exchanger inlet (outlet) temperature difference between water temperature and outdoor air wet bulb temperature control. On the basis of previous research on the outdoor air in order to make full use of favorable conditions, this paper puts forward the following control strategies: running alone in the cooling season at the beginning and end of the cooling tower in the middle of season, refrigeration by heat exchanger in (a) temperature control mode of water temperature and outdoor air wet bulb temperature of the composite pipe system cooling tower and ground.
Secondly, analysis on the cooling tower. The mathematical model of enthalpy balance equation of cooling tower is established based on Merkel's formula of effectiveness in analogy to the sensible heat exchanger number of heat transfer unit, cooling tower outlet temperature calculated by iteration. But the accuracy can not meet the requirements of automatic control system, so the the direct effect of cooling tower outlet temperature of outdoor air wet bulb temperature as control parameters.
Then on the basis of theoretical research, the research group set up a cooling tower for hybrid ground source heat pump experimental platform. Based on the experimental platform of Yun specific situation, a set of sensor and actuator field element layer design, PLC controller and single loop controller for the control layer, Lab VIEW PC software for management the three layer network control scheme, the hardware of the whole control system between the data exchange layer and the control of the overall design, debugging.
Again, according to the control strategy and the existing experimental platform for the development of a set of high degree of visualization, automatic control software using cooling tower hybrid ground source heat pump is convenient. The software can monitor the operating parameters on the system; to the system operation parameter setting and control; air conditioning system to the temperature gauge, system failure alarm; and can be real-time display system of data storage and printing.
Finally, the hardware and software control automatic control system of cooling tower composite GSHP on-site debugging and analysis, the control system is stable, the system of data acquisition, display, such as normal operation. The system can according to the change of water temperature of buried pipe and outdoor wet bulb temperature automatic control and cooling tower the underground pipe system operation mode, operation by setting appropriate parameters, can be run with the organic system of pipe cooling tower and ground, effectively reduce the temperature of the cooling water, improve the unit performance, ease the underground soil heat balance effect.

【学位授予单位】：东华大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU83

【参考文献】