A method for mapping the turbulence intensity and excess energy available to building mounted wind turbines over a UK City

Assessing the potential of proposed urban wind installations is hindered by insufficient assessments of both urban wind resource, and the effectiveness of commercial gust control solutions within built up areas. Evaluating the potential performance of wind turbines within the urban environment requires an estimation of the total energy that would be available to them were effective control systems to be used. This paper presents a methodology for estimating the excess energy content (EEC) present in the gusty urban wind, which is usually under represented when using assessments based only on mean wind speeds. The method is developed using high temporal resolution wind measurements from eight potential turbine sites within the urban and suburban environment. By assessing the relationship between turbulence intensities and the EEC, an analytical methodology for predicting the total wind energy available at a potential turbine site is proposed. Sensitivity analysis with respect to temporal data resolution on the predicted EEC is also demonstrated. The methodology is then integrated with an analytical methodology that was initially developed to predict mean wind speeds at different heights within a UK city based on detailed mapping of its aerodynamic characteristics. Additional estimates of turbulence intensities and EEC based on the current methodology allow a more complete assessment of the wind resource available. The methodology is applied to the UK city of Leeds as a case study and the potential to map turbulence intensities and the total kinetic energy available at different heights within a typical urban city is demonstrated. Copyright © 2015 John Wiley & Sons, Ltd.     

城市排水管网混合流数值模拟研究进展

全球气候变化背景下,城市洪涝灾害事件频发,城市雨洪模型将扮演愈发重要的角色。精细化的城市雨洪模型离不开对排水管网水流的准确模拟。混合流在排水管网系统中普遍存在,研究其机理和精确模拟技术对城市排水模型和雨洪模拟精度的提升意义重大。因此,从混合流数值模拟方法、混合流物理模型及城市排水管网模型等三个方面综合分析了国内外在混合流模拟和计算方面的研究进展,并分析了当前研究存在的不足,在此基础上对未来排水管网混合流方面的研究工作进行了展望。     

Energy balance analysis of wind-based pumped hydro storage systems in remote island electrical networks

The introduction of pumped hydro storage (PHS) systems in isolated electrical grids, such as those found in island regions, appears to be a promising solution that is able to face both the high electricity production cost and the continuously increasing power demand encountered in these areas. In this context, the current work presents a methodology for the sizing of PHS systems that exploit the excess wind energy amounts produced by local wind farms, otherwise rejected due to imposed electrical grid limitations. The methodology is accordingly applied to the Greek island of Lesbos. Initially, a calculation of the wind power penetration ability to the local grid is carried out and the corresponding curtailments of existing and future wind farms are determined. An integrated computational algorithm is then presented which simulates the operation of the system during an entire year and gives in detail the hourly operational status as well as the various energy losses of the system main components. Based on the application results obtained, the ability of the wind energy to remarkably contribute to the electrification of the remote islands becomes evident.     

平原河网圩区城市化对排涝的影响及排涝措施研究

越来越多的圩区正逐步踏入城市化进程,但由于圩区地势低洼、水面平缓、水动力条件较差等,在面对下垫面硬化等人类活动时排涝压力也越来越大。以张家港市福前晨东联圩为例,采用MIKE11模型模拟研究了城市化对圩区造成的排涝影响及相应排涝措施。结果表明,圩区城市化显著抬高了内河水位,会对周边排涝产生一定压力,加大了区域受灾可能;在城市化条件下,增加河道数量、提高水系连通性有助于改善河网的调蓄能力,可较好地缓解圩区城市化带来的河道水位抬升压力,在此基础上新增的闸泵工程发挥了更为积极的作用,可明显降低城区洪涝风险。     

基于SWMM模型的郑州市运粮河组团区内涝研究

针对以内涝为主要特征的城市洪水问题日趋突出,所造成危害日趋严重的现象,构建了基于地理信息系统（ArcGIS）的城市雨洪模型（SWMM）。以郑州市运粮河组团区为例,模拟分析了不同重现期降雨下规划区域的内涝情况,并选取具有代表性的易涝点进行优化分析。结果表明,该模型的计算结果可以为排水系统设计标准校核及优化设计方案提供一定的技术支持。     

基于SWMM模型的郑州市运粮河组团区内涝研究

针对以内涝为主要特征的城市洪水问题日趋突出,所造成危害日趋严重的现象,构建了基于地理信息系统(ArcGIS)的城市雨洪模型(SWMM)。以郑州市运粮河组团区为例,模拟分析了不同重现期降雨下规划区域的内涝情况,并选取具有代表性的易涝点进行优化分析。结果表明,该模型的计算结果可以为排水系统设计标准校核及优化设计方案提供一定的技术支持。     

Holistic methodological framework for assessing the benefits of delivering industrial excess heat to a district heating network

In Sweden, over 50% of building heating requirements are covered by district heating. Approximately 8% of the heat supply to district heating systems comes from excess heat from industrial processes. Many studies indicate that there is a potential to substantially increase this share, and policies promoting energy efficiency and greenhouse gas emissions reduction provide incentives to do this. Quantifying the medium and long-term economic and carbon footprint benefits of such investments is difficult because the background energy system against which new investments should be assessed is also expected to undergo significant change as a result of the aforementioned policies. Furthermore, in many cases, the district heating system has already invested or is planning to invest in non-fossil heat sources such as biomass-fueled boilers or CHP units. This paper proposes a holistic methodological framework based on energy market scenarios for assessing the long-term carbon footprint and economic benefits of recovering excess heat from industrial processes for use in district heating systems. In many studies of industrial excess heat, it is assumed that all emissions from the process plant are allocated to the main products, and none to the excess heat. The proposed methodology makes a distinction between unavoidable excess heat and excess heat that could be avoided by increased heat recovery at the plant site, in which case it is assumed that a fraction of the plant emissions should be allocated to the exported heat. The methodology is illustrated through a case study of a chemical complex located approximately 50 km from the city of Gothenburg on the West coast of Sweden, from which substantial amounts of excess heat could be recovered and delivered to heat to the city's district heating network which aims to be completely fossil-free by 2030.     

Experimental studies of surfactant-polymer flooding: An application case investigation

A great deal of oil field is currently produced using water flooding and the water cut has reached a high level, which requires enhanced oil recovery (EOR) techniques to improve the recovery. Surfactant-polymer (SP) flooding is the combination of surfactant flooding and polymer flooding. The polymer is added to increase the viscosity and viscoelasticity of the fluid while the surfactant is included to decrease the oil–water interfacial tension and change the wettability. Although the mechanism of SP flooding has been deeply investigated, the application of SP flooding on a specific oil field requires the selection of optimal SP system. Therefore, for the first time, we performed a series of experiments to determine the optimal SP system for high water-cut oil field. In the injection capability experiment, we observe that the SP system is injected into the core with less resistance compared with single polymer solution. In the flooding experiment, regardless of the polymer types, the improvement of recovery becomes significant when the injected PVs increases. SP flooding shows the higher improvement of recovery compared with single polymer flooding or surfactant flooding. Based on the performance of recovery improvement, we recommend the optimal SP system for the studied case is the combination of DQ-TSRP01 polymer and surfactant. The optimal injection parameters of this SP system are 1500 mg/L polymer concentration, 0.3 injection PV and the injection timing of 96% water cut. The finding of this study can help for better understanding of the application of SP flooding in high water-cut oil field production.     

Optimal design of fossil-solar hybrid thermal desalination for saline agricultural drainage water reuse

Ultra-high recovery solar thermal desalination of agricultural drainage water is presented as one solution to the historic extreme drought and long-standing salt accumulation problems facing California's fertile Central Valley region. Building on the results obtained from a recent pilot demonstration of a novel solar thermal desalination system, a techno-economic analysis is presented using an existing agricultural region as a case study. Three strategies are considered: continue retiring farmland as crop productivity wanes in future years, desalinate saline drainage water with a novel distillation process using natural gas as the fuel source, and desalinate using natural gas and solar as a hybrid energy source. The study is cast as a parametric optimization problem taking into account natural gas costs and water purchase contract pricing. The results show that with projections of the long-term effects and cost of salt accumulation in the region, solar thermal desalination is economically favorable over both the alternative of doing nothing (retire farmland) as well as implementing conventional (non-renewable) thermal desalination. Most importantly, the results indicate that solar thermal desalination is an economically-viable solution that can increase the sustainability of farming in the region and create a new, sustainable, scalable source of additional freshwater.     

Estimating the potential yield of small building‐mounted wind turbines

The wind profile in the urban boundary layer is described as following a logarithmic curve above the mean building height and an exponential curve below it. By considering the urban landscape to be an array of cubes, a method is described for calculating the surface roughness length and displacement height of this profile. Firstly, a computational fluid dynamics (CFD) model employing a k‐? turbulence model is used to simulate the flow around a cube. The results of this simulation are compared with wind tunnel measurements in order to validate the code. Then, the CFD model is used to simulate the wind flow around a simple pitched‐roof building, using a semi‐logarithmic inflow profile. An array of similar pitched‐roof houses is modelled using CFD to determine the flow characteristics within an urban area. Mean wind speeds at potential turbine mounting points are studied, and optimum mounting points are identified for different prevailing wind directions. A methodology is proposed for estimating the energy yield of a building‐mounted turbine from simple information such as wind atlas wind speed and building density. The energy yield of a small turbine on a hypothetical house in west London is estimated. The energy yield is shown to be very low, particularly if the turbine is mounted below rooftop height. It should be stressed that the complexity of modelling such urban environments using such a computational model has limitations and results can only be considered approximate, but nonetheless, gives an indication of expected yields within the built environment. Copyright © 2007 John Wiley & Sons, Ltd.     

An evaluation of enhanced oil recovery strategies for a heavy oil reservoir after cold production with sand

Cold heavy oil production with sand (CHOPS) is the process of choice for unconsolidated heavy oil reservoirs with relatively high gas content. The key challenge of CHOPS is that the recovery factor tends to be between 5% and 15%, implying that the majority of the oil remains in the ground after the process is rendered uneconomic. Continued cold production (without sands) is not productive for a post‐CHOPS reservoir because of the low oil saturation and depleted reservoir pressure in the wormhole regions. There is a need to develop viable recovery processes for post‐CHOPS reservoirs. Here, different follow‐up processes are examined for a post‐CHOPS heavy oil reservoir. In post‐CHOPS cold water flooding, severe water channeling is ineffective at displacing high viscosity heavy oil. Hot water flooding improves the sweep efficiency and produces more oil compared with cold water flooding. However, the swept region is limited to the domain between the neighboring wormhole networks, and the energy efficiency of the process is relatively poor. Compared with the hot water flooding case, steam flooding achieves higher oil production rates and lower water use. A cyclic steam stimulation strategy achieves the best performance regarding oil production rates and water usage. Based on our results, it is observed that thermally based techniques alone are not capable to recover the oil economically for post‐CHOPS reservoirs. However, it is suggested that techniques with combined use of thermal energy and solvent could potentially yield efficient oil recovery methods for these reservoirs. Copyright © 2015 John Wiley & Sons, Ltd.     

Hybrid solution and pump-storage optimization in water supply system efficiency: A case study

Environmental targets and saving energy have become ones of the world main concerns over the last years and it will increase and become more important in a near future. The world population growth rate is the major factor contributing for the increase in global pollution and energy and water consumption. In 2005, the world population was approximately 6.5 billion and this number is expected to reach 9 billion by 2050 [United Nations, 2008. www.un.org, accessed on July]. Water supply systems use energy for pumping water, so new strategies must be developed and implemented in order to reduce this consumption. In addition, if there is excess of hydraulic energy in a water system, some type of water power generation can be implemented.     

A new methodology for urban wind resource assessment

In the latest years the wind energy sector experienced an exponential growth all over the world. What started as a deployment of onshore projects, soon moved to offshore and, more recently to the urban environment within the context of smart cities and renewable micro-generation. However, urban wind projects using micro turbines do not have enough profit margins to enable the setup of comprehensive and expensive measurement campaigns, a standard procedure for the deployment of large wind parks. To respond to the wind assessment needs of the future smart cities a new and simple methodology for urban wind resource assessment was developed. This methodology is based on the construction of a surface involving a built area in order to estimate the wind potential by treating it as very complex orography. This is a straightforward methodology that allows estimating the sustainable urban wind potential, being suitable to map the urban wind resource in large areas. The methodology was applied to a case study and the results enabled the wind potential assessment of a large urban area being consistent with experimental data obtained in the case study area, with maximum deviations of the order of 10% (mean wind speed) and 20% (power density).     

A new type of double dispersion system for water control in fossil hydrogen energy development

Water cut is generally rising with the increase of water injection during water flooding development of fossil hydrogen energy reservoir. Conventional chemical profile control agents fail to work for a long time because they are easily affected by the temperature and salinity of fossil hydrogen energy reservoir to form crossflow channel. In this paper, a new dual-disperse profile control agent and flooding system (DDS) is proposed, which uses polymers and microspheres to plug polymer crossflow and improve oil recovery in fossil hydrogen energy development. The viscosity, suspension property, thermal stability and microsphere size expansion of the DDS are tested, and the oil displacement performance is evaluated. The results show that the viscosity of polymer solution is not affected by the addition of microspheres, and the DDS system has good suspension and thermal stability. Due to the adsorption of microspheres in polymers, the particle size of microspheres tends to increase with time. But the expansion slows down gradually, which is beneficial to deep migration. In terms of plugging efficiency, the optimum concentration of DDS is 1500 mg/L polymer and 500 mg/L microsphere, and the optimum injection volume is 0.5Pv. Compared with single polymer flooding system, the new dual dispersion system has better washing resistance and enhanced oil recovery in fossil hydrogen energy development.     

中原油田提高采收率优化技术

中原油田相继开展了CO2吞吐、N2驱、空气驱、合成聚合物驱、交联聚合物驱、微生物采油等项现场试验。鉴于中原油田地层温度高、地层水矿化度高,常规三次采油技术难以适应。对中原油田提高采收率的技术进行优化分析,对油田地质特点、开采特点和不同类型油藏采收率现状进行归纳,并对各技术潜力进行分析,得出结论:从储层条件和原油性质来看,适用中原油田的三次采油方法是CO2混相驱、天然气非混相驱,其次是化学驱。研究预测显示,通过水驱综合调整和气驱,可提高采收率11.1个百分点,达到40.5%,其中水驱综合调整增加可采储量3841×104t,提高采收率7.4个百分点,三次采油提高采收率3.7个百分点。总结出中原油田提高采收率的方向和思路:水驱提高采收率仍是油田当前开发的重点,重组开发层系、强化差层开采、提高油藏水驱采收率,大力发展堵水调剖等配套工艺技术、提高水驱控制程度,气驱仍是今后的主要发展方向。     

Exploration of the land potential for the production of biomass for energy in the Netherlands

The energy potential for energy crops and biomass residues in the Netherlands is assessed. The analysis explores the possible use of land for biomass production in the future. Various government memorandums and analyses of the expected future land use in various sectors have served as the basis for the assessment of the supply of and the demand for land in the future. In this study the potential supply of agricultural land is based on expected productivity increments in agriculture and assumptions with respect to the future demand for agricultural products. Various future claims for infrastructure, forestry, urban areas and nature are subtracted from the expected supply. The net projected supply of land ranges from zero to 52 000 ha in 2000 to 110 000-250 000 ha in 2015. The supply of agricultural land depends however on a number of supra-national factors, such as the European agricultural policy, world market developments and the agricultural production in the countries in Eastern Europe. Uncertainties remain, therefore, and the projected supply of agricultural land should be considered as a possible scenario based on current trends. If the calculated land potential is used for energy crops like miscanthus and short rotation coppice, this land could contribute 0-10 PJ in 2000 and 27-59 PJ in 2015. Secondary biomass yields, such as those from forestry, agricultural residues, wood from prunings, etc., could contribute a further 34 PJ in 2000, decreasing to approximately 28 PJ in 2015. Taken together these potentials could satisfy 1-1.5% of the energy requirements of the Netherlands in 2000 and 1.5-2.5% in 2015, provided that energy farming is an economically feasible activity for farmers.     

基于最大熵法的雨水排水系统灾害损失不确定性研究

快速城市化进程和全球气候变化加重了排水系统压力,导致城市内涝频繁发生,严重威胁社会经济发展和公众生命安全。为有效评估现有排水系统灾害损失,充分考虑各种不确定性因子对评估结果的影响,采用蒙特卡洛法随机生成致灾因子集,并基于SWMM模型计算其对应的灾害损失,结合最大熵法得到最小无偏概率估计的特征,构建灾害损失的概率密度分布函数,对安徽省合肥市某区域雨水排水系统进行灾害损失评估。结果表明,该方法可有效提高随机模拟的收敛速度,计算结果客观合理,在城市排水系统灾害损失及风险分析中具有推广应用价值。     

Application of an exhaust heat recovery system for domestic hot water

Typically, a great deal of heat is wasted in the drainage systems of large-scale public shower facilities, such as those in schools, barracks, and natatoriums. This paper enhances a heat pump system used in public shower facilities for exhaust heat recovery. The system consists of three sections for exhaust heat recovery: solar energy collection system, drainage collection system, and heat pump system. In the system, the energy from the solar energy collection system is used for the initial heating the shower's tap water. Afterwards, the drainage collection system collects the used shower water. Finally, the electric heat pump recycles the exhaust heat from the collected water to heat the shower's tap water. The operational practice of the system was presented. The drainage temperature and equipment capacity was optimized based on a practical example. The advantages of this heat pump system compared to gas-fired (oil-fired, coal-fired, electric) boilers are lower energy consumption, less pollution, and lower operating costs. Therefore, the system is superior in energy conservation and has a promising application prospect.     

Shower water heat recovery in high-rise residential buildings of Hong Kong

This paper investigates the potential for shower water heat recovery from bathrooms equipped with instantaneous water heaters in high-rise residential buildings of Hong Kong. A simple single-pass counter-flow heat exchanger installed horizontally beneath the shower drain is employed as a localized heat recovery measure for preheating cold water going to a water heater. The thermal energy exchange is evaluated using the effectiveness-number of transfer units (ε-NTU) approach. Shower usage patterns including shower operating time and water flow rate sampled from an interview survey via the Monte-Carlo sampling technique, together with the water temperatures at the shower heads, shower drains and cold water supply mains recorded in sample shower operations, are the input parameters. The results indicate that 4–15% shower water heat can be recovered through a 1.5 m long single-pass counter-flow heat exchanger for a drainage pipe of diameter 50 mm.     

沿海城市潮、雨遭遇下内涝模型及应用

以海南省海甸岛为例,基于带有地表属性信息的高精度DEM地形网格,依据城市分区精细产流方法计算产流,以分段线性化方式拟合实际雨水管网排水能力曲线,并建立了排水能力与潮位新型函数关系式,将水陆边界条件处理为可双向过水的模型边界,最终将地表产汇流模块、地下管网水动力模块和潮(洪)水漫滩淹没模块三者耦合,建立沿海城市潮、雨遭遇内涝模型,探讨潮、雨遭遇情况下城市水情和涝情特征及差异。结果表明,潮、雨遭遇情景下城市内涝整体情况更加恶化,积水面积剧增;不同区域内涝恶化原因不同,临海区域主要是潮水倒灌引起,城区内部区域恶化主要是高潮位顶托下内水无法外排所致;对比单独降雨下,典型内涝代表点积水深度平均增加0.22 m,积水历时平均增加7.70 h,深度积水持续时间显著延长。