数值模拟在地下水源热泵抽灌井布设中的应用

通过对不同布井方案地下水源热泵系统的地下水位与水温变化趋势预测分析,达到避免抽灌井热贯通的目的。文中以沈阳某工程为例,通过建立研究区地下水流与温度的耦合数学模型,模拟预测不同布井方案的地下水位与水温的动态变化情况。结果表明:方案一交叉布井抽水井水温变化较方案二集中布井抽水井水温变化要大,所以方案二布井要好于方案一。说明数值模拟能够准确预测不同布井方案对地下水位和水温变化情况及影响范围,继而通过调整布井方式避免抽灌井之间发生热贯通,提高热泵的利用效率,并为水源热泵工程的设计提供依据。     

中粗砂地层地下水源热泵热源井回灌策略

地下水源热泵能否长久高效运行,核心问题在于地下水的回灌问题。我国经过"十一五"期间可再生能源建筑应用示范项目和"十二五"期间可再生能源建筑应用示范城市和农村示范县的组织实施,已完成超过亿平方米的地下水源热泵示范项目。项目实施过程中,不乏有项目运行几年,出现回灌不畅、回灌不彻底甚至无法回灌的现象。本文为"十二五"国家科技支撑计划项目《浅层地热能集成应用技术与评估及示范》(2011BAJ03B09)的研究成果,以中粗砂地层典型地层为例,从回灌系统设计、回灌井及系统施工、系统维护保养、关键工艺技术提出不同的回灌要求,以确保地下水完成回灌,实现地下水源热泵的长期高效运行。     

地下水地源热泵优化布井的数值模拟研究

为了避免丹阳市滨江新城地下水地源热泵运行期间出现热堆积问题,保证浅层地热能的可持续开发利用,基于地下水渗流与热量运移的原理,通过建立地下水渗流与热量运移三维耦合数值模型,结合丹阳地区未来地下水地源热泵系统的运行工况,准确地模拟预测了丹阳市滨江新城地下温度场在长期运行过程中的热平衡发展趋势。在此基础上,规划设计了两种优化方案,有效避免了地下水地源热泵运行期间出现的热堆积问题。因此,地下水非稳定渗流与热量运移三维耦合数值模型是优化确定浅层地热能地下水地源热泵可持续开发利用方案的有效方法。     

水源热泵系统含水层中渗流场模拟及其对温度场的影响分析

地下含水层能量利用已经成为一项新的和热泵技术发展紧密联系的技术,准确预测水源热泵工程周围含水层中的流场分布时能量的有效利用意义重大.通过分析含水层储能的一般特点,提出流贯通,分析流贯通和热贯通的相互作用、相互影响及对工程实际的意义,并基于地下水水热运移的基本原理,建立地下水流动数值模型,在此基础上对沈阳某场地水源热泵工程的运行进行流场及温度场的数值模拟分析,给出产生流贯通的依据,进而研究流贯通对热贯通的影响,并为该地区的地下水源热泵工程设计提供一定的参考.     

地下水温数值模拟在水源热泵工程设计中的应用

为分析沈阳市某小区地下水地源热泵项目复合井结构的合理性和地下水热贯通程度,建立了地下水流与温度耦合数值模型,对不同换热温差下的地下水温变化趋势进行了模拟预测.模拟结果表明,采用复合井结构可以满足水源热泵工程取回水要求,且5℃换热温差比7℃更合理、安全.经过一个供暖期运行和对地下水温的实际监测,证明了模拟结果的准确性.     

水源热泵运行中多组份溶质的反应迁移模拟

地下水源热泵系统以其优越的节能性和环保性在全国范围内得到了推广应用,为了准确地了解地下水源热泵回水对地下水质的影响,本文以安阳市第五人民医院地下水源热泵系统为例,采用TOUGHREACT建立反应物迁移转化模型,对水源热泵系统长期运行中地下水化学组分、含水介质中矿物组分和矿化度的变化情况进行模拟研究。研究结果表明:水源热泵抽回水过程中地下水组分浓度(K~+、Na~+、Ca~(2+)、Mg~(2+)、HCO_3~-)变化程度较小;含水介质中的方解石和云母均发生了不同程度的沉淀作用,钙长石矿物发生了溶解作用;回水井周边的含水介质孔隙度变小,预测期内孔隙度降低了0.0011。水源热泵系统的长期运行对地下水化学组分、含水介质中的矿物组分和孔隙度的影响较小。     

地下水源热泵技术在天津市区应用主要问题探讨

可提供清洁能源的地下水源热泵技术越来越受到人们的青睐,在天津已发展到12家之多,经济效益和社会价值都比较显著。但是,该技术在开采地下水资源方面仍存在一些不足,尤其是回灌效果达不到要求,是政府决策者迟迟不敢快速推动的一个主要原因。本文通过天津市红光中学地下水源热泵系统工程取用地下水设计,结合其它正在利用的热泵工程,对地下水源热泵技术在天津市区开采地下水资源方面几个关键问题进行研究,提出了经济合理可行的技术方案。     

地下水源热泵系统的运行机制对渗流系数影响的实验研究

以某市相距不远且地下水、岩层结构很接近的2个地下水源热泵系统为研究对象,在夏季对其水井抽、灌流量和水位进行了为期40多天的检测。2个系统运行机制不同,1个为间歇运行、1个为连续运行。将检测数据代入井群地下水流动数学模型,分析得到抽、灌井渗流系数的动态值,进而得到渗流系数值与运行时间的函数关系,作为渗流系数衰减的预测模型。在此基础上,对2个系统长期运行的渗流系数的衰减分别进行了预测。分析结果表明:2个系统运行120天,间歇运行的系统的渗流系数衰减约为14.4%,连续运行的系统的渗流系数则衰减约为39.7%。     

地下水源热泵运行模式对地温场效能影响研究

基于上海市某地下水源热泵工程项目,采用COMSOL Multiphysics有限元分析工具建立二维简化的热渗耦合数值模型,模拟采能区含水层多孔介质热量运移过程,并利用热泵运行3年的现场监测数据进行模型的识别与验证。探讨热泵系统冷、热负荷设计和抽、灌模式两个方面对采能区地温场效能的影响,分析和预测不同工况下热泵运行期间地温场的演变特征,最后对系统的运行效果进行评价。结果表明:该热泵系统按原设计方案运行时,抽灌井短期运行效果良好,但在第7个供暖期末将出现热贯通现象,长期运行将不利于热井的取热; 如果减小20%热负荷、增加20%冷负荷,会使冷影响区扩散速度降低46.3%,系统运行效果得到显著改善,在模拟的9个运行周期内并未出现热贯通现象,说明合理调节冷、热负荷有利于热泵系统的长期稳定运行; 当冷、热负荷恒定时,分别减小10%和20%的循环水量将会使冷影响区扩散速度分别降低9.3%和15.7%,有效地缓解了热贯通的发生,且仍能满足项目对于制冷供暖的需求,进一步阐明了地下水源热泵系统宜采用“大温差、小流量”的抽灌模式。     

地下水水源热泵技术与空调系统应用

本文研究了地下水水源热泵技术与空调系统特点,结合工程实例对该系统工程应用设计和设备选型进行了详细比较,得出其地下水水源热泵技术空调系统设计方案,并对该方案的工程应用和节能性能进行分析,得出地下水水源热泵空调系统在政策、运营费用、节能减排等方面具有明显的优越性。     

Development of dual-source hybrid heat pump system using groundwater and air

To achieve high heat pump efficiency, groundwater heat pump (GWHP) system uses groundwater, which is relatively stable AT temperature compared with outdoor air, as a heat source. However, it is difficult to meet annual heating and cooling loads using only groundwater as a heat source. In order to optimize the operation method of GWHP systems, it is necessary to develop a system utilizing both groundwater and air sources according to the building load conditions. Furthermore, during intermediate seasons (such as spring and autumn) with reduced heating and cooling loads, GWHP system is less efficient than air source heat pump (ASHP) system according to temperature conditions. In order to more efficiently use GWHP systems, it is necessary to develop a system which utilizes both groundwater and air sources according to temperature conditions and building loads. This research has developed a GWHP system that employs a hybrid heat pump system with groundwater wells using dual groundwater and air heat sources. In this paper, the annual performance of the developed system has been calculated, and several case studies have been conducted on the effect of introduction location, refrigerant and pumping rate. Furthermore, the coefficient of system performance and the effects on underground environments have been evaluated by real-scale experiment using two wells.     

Numerical simulation of ground heat and water transfer for groundwater heat pump system based on real-scale experiment

The groundwater heat pump (GWHP) system is an open-loop system that draws water from a well or surface water, passes it through a heat exchanger and discharges the water into an injection well or nearby river. By utilizing the relatively stable temperature of groundwater, GWHP system can achieve a higher coefficient of performance and can save more energy than conventional air-source heat pump (ASHP) system. The performance of the system depends on the condition of groundwater, especially temperature and depth, which affect performance of the heat pump and system. For the optimization of design and operation of GWHP systems, it is necessary to develop a simulation tool which can predict groundwater and heat flow and evaluate system performance comprehensively. In this research, 3D numerical heat-water transfer simulation and experiments utilizing real-scale equipment has been conducted in order to develop the optimization method for GWHP systems. Simulation results were compared with the experimental results, and the validity of the simulation model was confirmed. Furthermore, several case studies for the optimal operation method have been conducted by calculating the coefficient of performance on various groundwater and well conditions.     

地下水源热泵系统用于写字楼的经济性研究

基于莱工程实例,采用BIN法对其全年能耗进行了分析计算,以此为基础对比了地下水源热泵系统和常规水冷空调系统的费用年值,并分析了地下水源热泵系统的追加投资回收期.计算结果显示虽然地下水源热泵系统的初投资较高,但其费用年值仅为常规水冷空调系统的91.6％,且3.8年左右就可把追加投资完全收回,所以使用地下水源热泵系统不仅可...     

Modeling and performance evaluation of shallow ground water heat pumps in Beijing plain, China

The use of groundwater for cooling and heating purposes is of interest from both the economical and the ecological perspective. The groundwater heat pump (GWHP) system utilizes groundwater as alternative renewable and clean energy source for space heating and/or cooling, withdraws water from a production well, passes it through a heat exchanger and discharges the water into an injection well. By utilizing the relatively stable temperature of groundwater, GWHP system can achieve a higher coefficient of performance. Due to the utilization of groundwater stored in the aquifer, the assessment of the hydraulic capacity of the aquifer based on numerical groundwater models is always needed for the optimum design and the efficient performance of GWHP. In this paper, numerical methods of underground heat-water transfer, energy balance method and thermal storage method were presented to calculate the capacity of unit area of shallow groundwater aquifer. The model results indicate that the numerical method, which is based on performance efficiency of GWHP, represents the behaviour of groundwater pumping/recharging processes, and serves better than energy balance method and thermal storage method, in addition it has been proven itself that this method has the advantages of energy saving and environmental protection. The calculated capacity is positively related to aquifer thickness. It is found that it is easy for ground water recharge in alluvial and pluvial fan located at the piedmont, while the calculated capacity is relatively smaller compared with that of south-east plain where it is not easy for groundwater recharge.     

地源热泵系统工作井优化布设地下水热量运移模拟

针对地源热泵空调系统工作井优化布设问题,通过建立理想的＂对井抽-灌＂概念及数学模型,模拟拟建地下水源热泵系统特定水流及热源条件下抽水、回灌井不同间距夏季运行期间地下水热量运移过程,为抽、灌井合理间距确定等实际应用提供理论参考和依据。根据数值模拟结果,抽、灌井不同井间距对该热泵系统夏季运行期间地下水热量运移过程影响显著;...     

Exergetic cost analysis of a space heating system

In order to evaluate and improve the design of space heating systems with groundwater source heat pumps (GWHP), common design practices should be examined. In this paper, a GWHP system with common design is studied. The COP of the heat pump is 3.5 at design condition. The system is divided into five subsystems, and exergetic cost analysis is performed on it based on structural theory of thermoeconomics. The results show that the three largest relative exergy destructions and lowest exergy efficiencies occur in power generation and distribution, heat pump, and terminal unit subsystems with relative exergy destructions of 71.2%, 17.1% and 7.02% and exergy efficiencies of 32.8%, 54.8% and 65.6% respectively. The three subsystems also have the largest increases of unit exergetic costs of 2.04 W/W, 2.15 W/W, and 2.73 W/W respectively. Therefore, designers of GWHP space heating systems should pay close attention to heat pump and terminal unit subsystems, especially to the latter one because of its larger increase of unit exergetic cost. The unit exergetic cost of the system final exergetic product is 7.92 W/W. This value can be used to evaluate the system and compare it with others from the viewpoint of energy conservation.     

初探水文地质工程勘察在开发地源热泵中作用

开发地源热泵,利用地下水作为地源热泵的冷热源,需要进行专门的水文地质勘察,勘察重点要取得冷热源井的出水量、回灌量、地下水温度、水位、流速、流向和水质资料,选择理想的供水含水层,评估地下水可开采量,初步确定抽灌井比等,本文结合工程实例对地源热泵水文地质勘察需要解决的问题做初步的探讨,说明水文地质勘察在开发地源热泵中具有十分重要的意义。     

严寒地区地下水源热泵运行方式适宜性研究

基于颗粒迁移理论,以严寒地区某工程为例,对严寒地区地下水源热泵采用不同运行方式对含水层参数的影响进行研究,结果表明在严寒地区采用变流量运行方式对含水层参数的影响较小,宜在严寒地区地下水源热泵工程中得到推广。     

地下冷库热湿绝缘实践及其效果

地下冷库作为储藏食品的地下建筑物,是地下空间开发利用中的一种有效途径。相对于地面冷库,它具有自己的一系列特点,但若未做好建筑和热工设计,则投产后会出现许多问题。本文通过实测对比,以及有限元计算,分析了地下冷库的热状况,包括岩层中的温度场,库壁耗冷量等。本文指出在炎热地区,地下冷库应当设置热湿绝缘层,以避免上述问题的发生,并且分析了热湿绝缘的效果。