地下含水层储能系统的(火用)分析

探讨了地下含水层储能系统回灌期输入地下含水层的能量、火用及抽水期从地下含水层回收的能量、火用的计算公式。通过算例,计算了大流量、低回灌水温度,小流量、高回灌水温度及适中的流量、回灌水温度的3种工况的储能效率及火用效率,小流量、高回灌水温度运行模式的火用效率最高。将水泵消耗的电能计入火用效率,对火用效率进行修正,小流量、高回灌水温度运行模式具有更大的优势。     

抽/灌井场热贯通与含水层自然流动关联性实验研究

建立抽/灌井群地下水热运移实验系统,开展抽/灌过程含水层温度场与地下水渗流场演化规律研究,特别对有、无初始自然流的水平流、垂直交叉流和静态流的影响作用进行系统研究。结果表明,地下水初始自然流的方向和流速对含水层温度场的影响范围和程度起着关键作用,表现出自然流与抽/灌渗流交互的影响。当自然水平流与抽/灌渗流流向相反时,流速越大,抽水温度受到回灌水温度影响的推迟性越大,延迟热贯通时间和减轻热交互程度。相反,流向相同时,将加剧热贯通和热交互影响。对于垂直交叉流态,流速越大,地下水渗流场及其温度场影响范围偏移程度越大,通常减轻热贯通和热交互影响。     

多层含水层中同井回灌地下水源热泵特性分析

在适当简化了多层含水层和抽灌同井的基础上,分析了多层含水层中同井回灌地下水源热泵水力和热力特性。随着中间含水层竖向渗透系数的增加,抽、回水口降深绝对值减小,抽水和回灌相对容易;中间弱透水层厚度减小时,抽、回水口降深绝对值有所降低,但降低不明显;抽水流量增加,抽、回水口降深绝对值基本呈线性增加,从而增加抽水和回灌压力。中间弱透水层的存在,显著地降低了抽水温度降,大大增加了含水层热影响范围,即使弱透水层很薄,也能起到很好阻隔作用,在这种条件下井的出水温度对于流量的加大不敏感。因此在抽水和回灌允许的情况下,可以加大抽水流量,使井承担更大的负荷。     

地下水地源热泵热源井设计方法研究

结合水文地质、暖通空调、含水层储能等相关知识,给出了一套包含地下水动力学和热力学设计的热源井简化设计方法,设计内容包括抽水井和回灌井的井径、过滤网、井流量、井数、井间距等.该方法可以应用于工程设计.     

热负荷对同井回灌地下水源热泵的影响

模拟研究了热负荷对同井回灌地下水源热泵抽水和回灌降深、抽水温度和热影响范围的影响。研究发现,随着抽水流量的增加,抽水和回灌降深绝对值增加,抽水温度降低;对于易于出现热贯通的含水层,在条件允许的情况下应采用小抽水温差和大抽水流量。     

天津第二粉土粉砂微承压含水层回灌试验研究

天津、上海等地已尝试采用回灌措施控制基坑降水引起的承压含水层水头下降及引起的沉降,然而目前回灌理论尚缺乏研究,在粉土粉砂微承压含水层中进行回灌的可行性也急需研究。因此本文在邻近天津某地铁基坑工程的场地外开展了一系列单井回灌、群抽群灌试验以及单抽单灌现场试验。试验结果表明,在粉土、粉砂为主的土层进行回灌是可行的。采用抽水试验得到的水文地质参数可以用于预测回灌的水位抬升,但是相同流量下,在距中心井较近距离内(约5~7 m内),回灌产生的水位上升值显著大于抽水导致的水位降落值。加压回灌可以显著提高回灌效率。回灌量与抽水量维持在相近水平可以有效控制周边地表及建筑物沉降。当回灌停止后,周边地表沉降有快速发展的趋势,因此在实际工程中,抽水停止后应适当延长回灌时间,逐步减小回灌量,使地下水位逐步回稳,避免抽灌活动结束后沉降的快速发展。采用双井组合回灌技术可有效的控制回灌井回扬时引起的含水层水位的下降。     

地下含水层同层储能应用中储能井布置方法研究

适合储能的含水层应该是承压含水层 ,储能应该采用同层方式。合理布置储能井间的相对位置 ,可以有效抵消原有地下水的流动以及渗流系数不一致的影响。利用井之间的渗流耦合作用 ,在储能井之间布置调节井 ,主动控制储能水的波及范围 ,可以实现储能井布置的相对“紧凑”。     

抽灌井的布置方式对地下水流场和温度场的影响

通过分析地下水流场和温度场的状态,确定适合水源热泵系统的最佳抽灌井布置方式。以沈阳市某住宅小区为例,利用Flow Heat1.0软件,分析了冬季在3种顺排布置和2种叉排布置情况下,抽灌井周边的地下水流场和温度场的变化情况,地下水源热泵系统运行的最佳状态是不影响地下水流场和温度场的现况。结果地下水源热泵系统受地下水流场、温度场、井距、热对流、运行模式等诸多因素的影响,在该影响因素的影响下水源热泵运行效率有所降低,通过对五种工况的最不利抽水井和回灌井的比较分析,发现抽水井的水位下降值越小、回灌井的水位上升值越小,水温度值变化越小越好。本次实例中第五种布置方式1,6,11,16号井为抽水井,其余为回灌井的布置方式最为合理,此时水位值和温度值的变化量最小。     

CO2作为含水层压缩气体储能系统工作流体的数值模拟研究

含水层压缩CO₂储能是非常契合国家“双碳”战略的大规模储能技术,为进一步提高储能效率,本文重点研究含水层压缩CO₂储能系统运行过程,采用T2WELL/ECO₂N分析含水层压缩CO₂的周循环运行模式下的性能,包括含水层气相饱和度、含水层温度、井口压力、循环周期内的储能效率及不同含水层埋深情况下系统储能效率的变化情况。模拟结果表明：在初始气囊建立阶段,距离井筒最近处的气体饱和度最高,含水层温度最低,这是由于距离井筒越近,压力梯度越大,含水层中的水在压力梯度的作用下逐渐被CO₂驱替;在储能-释能循环阶段,由于含水层中固体颗粒物的阻碍和渗透性的限制,井口处的循环压力从13.94 MPa,逐渐增加到14.23 MPa,并呈周期性的变化。随着含水层深度加深,抽采出来的CO₂温度更高、密度更大,从而获得更多的能量,使储能效率从88.6%提升到95.2%,因此含水层越厚越有利于系统的安全稳定运行,但储能效率会随着循环次数的增加而降低。     

季节性含水层储能系统在住宅中的应用

提出一种含水层储能的住宅集中空调系统。在分析含水层储能的数学模型及其离散算法的基础上，编制了计算机模拟程序，利用该程序对影响含水层储能效果的若干因素进行了模拟计算，认为集中回灌比分散回灌效果好；在回灌热量一定的情况下，小流量大温差运行效果较好；地质条件对系统热效率和抽水温差有影响。     

热弥散对同井回灌地下水源热泵的影响

综述了多孔介质和含水层蓄能中常用的热弥散模型,把热弥散模型归结为两类：速度一次方模型和含水层滞止导热系数倍数模型。对同井回灌地下水源热泵（GWHPPRSW）引起的地下水的换热,针对这两类模型进行了数值求解。随着热弥散的加强,抽水温度降加大。含水层中某些地方,温度降随着热弥散的增加而减小,且变化幅值较大。含水层热影响范围随着热弥散的加强而加大。速度一次方模型的计算结果较含水层滞止导热系数倍数模型的计算结果的抽水温度降大,热影响范围小。     

An aquifer thermal storage system in a Belgian hospital: Long-term experimental evaluation of energy and cost savings

Over a three years period, an aquifer thermal energy storage system was monitored in combination with a heat pump for heating and cooling of the ventilation air in a Belgian hospital. The installation was one of the first and largest ground source heat pump systems in Belgium. Groundwater flows and temperatures were monitored as well as the energy flows of the heat pumps and the energy demand of the building. The resulting energy balance of the building showed that the primary energy consumption of the heat pump system is 71% lower in comparison with a reference installation based on common gas-fired boilers and water cooling machines. This corresponds to a CO₂-reduction of 1280 ton over the whole measuring period. The overall seasonal performance factor (SPF) for heating was 5.9 while the ATES system delivered cooling at an efficiency factor of 26.1. Furthermore, the economic analysis showed an annual cost reduction of k€ 54 as compared to the reference installation, resulting in a simple payback time of 8.4 years, excluding subsidies.     

Productivity of Aquifer Thermal Energy Storage (ATES) in The Netherlands

Various forms of Aquifer Thermal Energy Storage (ATES) systems have been applied in The Netherlands. The systems differ with regard to the temperature at which the energy is stored, the type of energy supply system to which the storage belongs, and the type of user. The paper describes several different applications of ATES systems which may be used for heat storage, cold storage, and combined heat and cold storage. The productivity of these systems varies, and the payback period varies from 0 to 10 years. The paper compares cost-benefits for conventional and cold storage systems above and below ground, and reviews potential applications for industrial and commercial/institutional uses of ATES systems in The Netherlands.     

承压含水层贮能数学模型研究

本文提出了一个承压含水层中三维对流-热弥散模型。模型的控制方程不仅如通常那样包含对流项和传导项,还包含许多文献中常被忽略的热机械弥散项。模型被用来描述上海的一系列含水层贮能试验,模拟得出的温度与野外资料拟合得非常好(相对误差2.8％-4.5％)。     

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.     

Field study of organic water quality changes during groundwater recharge in the Palo Alto Baylands

Water quality data are presented from a field study in which reclaimed water is injected directly at a rate of 61 s⁻¹ into an aquifer in the Palo Alto Baylands on the margin of San Francisco Bay. Water quality changes are observed by analyzing samples from wells at distances of 10–40 m and in differing directions from the injection point. Data on trace organic pollutants show evidence of retardation of movement in varying degrees, presumably caused by adsorptive interactions with the aquifer. Trihalomethane compounds show evidence of biodegradation in the aquifer. The concentration of total organic substance as measured by TOC and COD is decreased significantly by biodegradation, but total organic halogen appears unaffected by aquifer passage.     

Groundwater Model of Conditions in Liverpool Sandstone Aquifer

T his study considers the groundwater conditions for the period 1948–82 in the Permo-Triassic Sandstone aquifer of the Liverpool area. During this period, significant changes have occurred in the abstraction patterns and a new railway tunnel has been constructed below sea level in Central Liverpool. To understand the flow conditions within the aquifer, detailed studies have been carried out into the aquifer properties, the influence of rivers and tunnels, and the estimation of recharge. It is found that conventional rainfall recharge accounts for only one-third of the total recharge.
Numerical model solutions were used to check the adequacy of the understanding of the flow processes and the solutions have confirmed that the rising water levels in Central Liverpool result from high recharge and a reduction in abstraction. Having validated the model by comparisons with field data, the model was then used to predict the probable future water level changes.     

Different design scenarios related to an open loop groundwater heat pump in a large building: Impact on subsurface and primary energy consumption

A multidisciplinary methodology is proposed for analyzing opportunities to use existing boreholes and an open-loop groundwater heat pump to provide summer cooling needs for large university buildings in Turin (NW Italy). The approach starts from a model of the buildings to determine the time profile of the cooling load. This curve is then coupled with a model of the off-design behaviour of the heat pump, which allows calculation of its energy performance (coefficient of performance, electricity consumption, etc.) as well as profiles of water discharge to the aquifer in terms of mass flow rate and temperature.Covering the peak energy needs of the buildings requires a variable amount of groundwater during the day. This could be provided varying the withdrawals from the aquifer but, as possible alternatives, two storage system solutions are examined: (1) chilled water storage and (2) groundwater storage. Simulations show that in both cases the use of storage systems produces environmental advantages, as the extent of the thermal plume reduces significantly. Moreover, chilled water storage presents a benefit in terms of reduced total primary energy consumption. The additional costs incurred by storage systems could necessitate public funding as well as system optimization.     

EXPLORATION OF AQUIFER MANAGEMENT OPTIONS USING A GROUNDWATER MODEL

A methodology is described for harnessing the predictive capacity of a groundwater model to underpin aquifer management decisions for changing abstraction within a licensing regulatory framework. The use of a 'baseline predictive simulation' is advocated from both aquifer management and scientific perspectives, and an example of groundwater modelling predictive work on the Nottingham-Doncaster Sherwood Sandstone aquifer system is used to illustrate the methodology. Differences between the baseline predictive simulation and a predictive simulation are processed to extract quantitative information (spatially and temporally) on the response to changes in aquifer stresses. An explanation is given on the use of this information to aid aquifer management decisions for achieving environmental targets. The importance of the aquifer diffusivity with respect to a predictive simulation exercise is highlighted.     

Transformation of organic matter and bank filtration from a polluted stream

A case study of the examination of the changes of organic matter in a small, highly polluted stream and the adjacent alluvial aquifer is presented. The investigated stream was actually a collector of effluents from baker's yeast and pharmaceutical industries. The stream was characterized by a COD of several thousands of mg O₂ l⁻¹, most of which was biodegradable organic matter. Biodegradation processes took place in the surface water, with consequent oxygen depletion in the stream. The organic matter content of the river sediment was more than 10% of its dry weight. Bank filtration of organic substances was investigated in a number of observation wells at distances of 5–150 m from the river (under different hydrological conditions). The infiltration of organic matter from the polluted stream into the aquifer was found to be significant only at hydrological conditions where the water level exceeds the altitude of the stream bed. The organic matter present in groundwater samples was mainly a humic/fulvic type, and was not degraded during the 64 days of the laboratory biodegradation experiment.