Hydraulic Interconnection Research Articles

A variable stiffness anti-roll system for railway vehicles based on a hydraulic interconnection approach

In order to alleviate the trade-off between vehicle ride comfort and derailment safety offered by the passive anti-roll bar (ARB), this study proposes a semi-active hydraulically interconnected variable stiffness anti-roll system (HIVSAS). The HIVSAS has the advantage of providing non-constant, multi-mode anti-roll stiffness and even removing it. First, based on the mathematical model of the main components of the HIVSAS, the physical parameter model is built in AMESim. The accuracy of the model is verified by bench tests. Then, the effect of the key parameters of the HIVSAS on the anti-roll stiffness characteristics is analysed. Finally, the dynamic performance of three vehicles equipped with different anti-roll systems is investigated by numerical co-simulation. The straight and curved (with a radius of 600 m) tracks are high-speed rail lines in China. The simulation results show that both the lateral ride comfort and the derailment safety of the HIVSAS-equipped High Speed Train (HST) are improved when exposed to rail irregularities and crosswind coupled excitation. Even accounting for flexible carbody, the HIVSAS-equipped HST outperforms in lateral comfort. The HIVSAS provides a feasible and practical research route for the anti-roll system, improving the line adaptability, curve passing speed and ride comfort of railway vehicles.

Hydrochemical and Stable Isotope characteristics of surface water and groundwater in Xiliugou and Wulagai River basin, North China

The investigation of the correlation between groundwater and surface water in terms of water origin and transformation is crucial for comprehending hydrological processes . Focuses on the Wulagai river and Xiliugou river basin located in East and West Inner Mongolia. It employs hydrochemical analysis and stable HO isotopes techniques to investigate the hydrochemical properties of the basin and quantitatively assess the interconversion between groundwater and surface water. The results suggest that the Xiliugou and Wulagai river basins were originally nourished by atmospheric precipitation, with lower δD and δ18O values in groundwater compared to surface water, attributed to factors such as evaporation, water vapor source, altitude, and latitude. The surface waters in the Xiliugou and Wulagai River exhibit dominance of Na•Ca-SO4•HCO3 and Ca•Na-HCO3 types, respectively, while the groundwater is characterized by dominance of Na•Ca-HCO3 and Ca•Mg-HCO3 types, respectively. The water chemistry of surface water and groundwater in the two basins is influenced by water-rock interactions and processes of evaporation and concentration, primarily observed in the dissolution of carbonate rocks and evaporites. Hydrograph separation using End-Members Mixing Analysis (EMMA) revealed that during the growing season, groundwater in Xiliugou was primarily recharged by precipitation (76.87 %) and surface water (23.13 %), while in Wulagai, groundwater was mainly recharged by precipitation (65 %) and surface water (35 %). The presence of comparable hydrochemical constituents and shared regulatory mechanisms between groundwater and surface water within a given basin provides further evidence of a discernible hydraulic interconnection, primarily driven by the replenishment of groundwater through surface water recharge.

Purpose-Designed Hydrogeological Maps for Wide Interconnected Surface–Groundwater Systems: The Test Example of Parma Alluvial Aquifer and Taro River Basin (Northern Italy)

Hydrogeological maps must synthesize scientific knowledge about the hydraulic features and the hydrogeological behavior of a specific area, and, at the same time, they must meet the expectations of land planners and administrators. Thus, hydrogeological maps can be fully effective when they are purpose-designed, especially in complex interconnected systems. In this case study, purpose-designed graphical solutions emphasize all the hydraulic interconnections that play significant roles in recharging the multilayered alluvial aquifer, where the majority of wells have been drilled for human purposes, artificial channels are used for agricultural purposes, and the shallow groundwater feeds protected groundwater-dependent ecosystems. The hydrogeological map was then designed to be the synthesis of three different and hydraulically interconnected main contexts: (i) the alluvial aquifer, (ii) the hydrographic basin of the Taro losing river, and (iii) those hard-rock aquifers whose springs feed the same river. The main hydrogeological map was integrated with two smaller sketches and one hydrogeological profile. One small map was drawn from a modeling perspective because it facilitates visualization of the alluvial aquifer bottom and the “no-flow boundaries.” The other small sketch shows the artificial channel network that emphasizes the hydraulic connection between water courses and groundwater within the alluvial aquifer. The hydrogeological profile was reconstructed to be able to (i) show the main heterogeneities within the aquifer system (both layered and discontinuous), (ii) visualize the coexistence of shallower and deeper groundwater, (iii) emphasize the hydraulic interconnections between subsystems, and (iv) suggest the coexistence of groundwater pathways with different mean residence times.

First steps towards interlocking modular microfluidic cooling substrates (i-MμCS) for future silicon tracking detectors in High Energy Physics (HEP)

In future High Energy Physics detectors, the coverage of large surfaces with silicon pixel chip sensors poses a challenge for the sensors positioning, for their cooling, assembly, and interconnection. The use of a cooling substrate on which the sensors are glued is typically limited by the bulky and complicated hydraulic interconnection between adjacent substrates. In this research, a new type of cooling substrate is presented. Its design is based on microchannels, where additive manufacturing of plastic and ceramic materials has been considered an alternative to the current silicon etching process. A solution to the mechanical and hydraulic interconnection problem is achieved through a modular interlocking concept. Design optimisation was followed having identified three relevant parameters, plug-and-ply, interchangeability and sealing performance, which qualify the substrates interconnection and guaranty their correct positioning. This paper poses the bases to a new substrate category where modularity, re-workability and easy connectivity are the strong points. This concept could find applications also outside High Energy Physics experiments such as hardware cloud computing and medical detectors.

Isotope and hydrochemical systematics of groundwater from a multi-tiered aquifer in the central parts of Indo-Gangetic Plains, India – Implications for groundwater sustainability and security

The Indo-Gangetic multi-aquifer system provides water supplies to the most populous regions of the Indian subcontinent, however precise knowledge on the sources and dynamics of groundwater is still missing. Environmental isotopes (2H, 18O, 13C, 3H and 14C) and hydrochemical modeling tools were used in this study in the multi-tiered aquifers underlying the Middle Gangetic Plains (MGP) to investigate the source of recharge, aquifer dynamics and inter-connectivity among aquifers. Within a depth span of 300 m, three aquifers, with contrasting recharge sources and dynamics, were delineated in this Sone-Ganga-Punpun interfluve region, with limited cross-aquifer hydraulic interconnections. The chemistry evolves from Ca-HCO3 to Na-Ca-HCO3 in the shallow semiconfined Aquifer-I with a mean transit time of 20–23 years. The dominant recharge to Aquifer-I is from the river inflows and rainwater percolation through paleochannels. The semi-confined to confined Aquifer-II holds fresh quality groundwater with mixed water facies (Mg/Ca-Na-HCO3). The modeled age of Aquifer-II groundwater is found to be 205–520 years, which is supported by presence of negligible tritium and minor variations in stable isotopes. Outcrop regions of Aquifer-II sediments in the marginal alluvial areas and deep-seated paleochannels in the southwestern part are the potential zones for Aquifer-II recharge. A deep confined Aquifer-III with fresh quality of groundwater is identified below 220 m. This aquifer is characterized by old age (~3.5 to 4.7 ka BP) and enriched δ18O (−5.7‰). These results along with the existing paleoclimate records of this region infer that Aquifer-III is recharged during an arid climate. The marginal alluvial plains are the probable recharge zones for Aquifer-III. This study helped in conceptualizing the groundwater flow paths in multi-tiered aquifers of MGP. The knowledge and understanding would extend crucial inputs for the sustainable development of deep aquifers not only in the MGP but also in other regions of Indo-Gangetic Plains.

Dynamic load shifting for the abatement of GHG emissions, power demand, energy use, and costs in metropolitan hybrid wastewater treatment systems

The installation of satellite water resource recovery facilities (WRRFs) has strengthened the ability to provide cheap and reliable recycled water to meet the increasing water demand of expanding cities. As a result, recent studies have attempted to address the problem of how to optimally integrate satellite systems with other sectors of the urban sphere, such as the local economy, the power supply, and the regional carbon footprint. However, such studies are merely based on the spatial domain, thus neglecting potential time-dependent strategies that could further improve the sustainability of metropolitan water systems. Therefore, in this study a new conceptual framework is proposed for the dynamic management of hybrid systems comprised of both centralized and satellite WRRFs. Furthermore, a novel set of integrated real-time control (RTC) strategies are considered to analyze three different scenarios: 1) demand response, 2) flow equalization of the centralized WRRF and 3) reduction of greenhouse gas emissions. Data from a case study in California is used to develop an integrated dynamic model of a system of 8 facilities. Our results show that by dynamically shifting the dry-weather influent wastewater flows between hydraulically connected WRRFs, a reduction in power demand (up to 25%), energy use (4%), operating costs (8.5%) and indirect carbon emissions (4.5%) can be achieved. Therefore, this study suggests that a certain degree of hydraulic interconnection coupled with dynamic load-shifting strategies, can broaden the operational flexibility and overall sustainability of hybrid WRRF systems.

Three-dimensional hydrostratigraphical modelling supporting the evaluation of fluoride enrichment in groundwater: Lakes basin (Central Ethiopia)

Study regionThe Lakes Basin is located in the Main Ethiopian Rift. It covers the northern part of the rift valley basin, the Upper Awash River basin, and some sub-basins from the Omo River basin. Due to the presence of high fluoride (F−) content, natural contamination of groundwater has long been recognized as a water-related health issue in the area. Study focusA multidisciplinary research effort, including geological, hydrogeological, hydro-chemical, and geophysical investigations, was adopted to understand the 3D hydrogeological conceptual model and to evaluate F− enrichment in groundwater. New hydrological insights for the regionThe 3D hydrogeological conceptual model shows a complex hydrogeological environment and a clear hydraulic interconnection between different aquifers. The geological setting has deeply influenced the geometry of the aquifers, recharge and discharge areas, and F− enrichment in groundwater. Two hydrogeological units, namely sedimentary and volcanic multi-aquifers, were identified. The analyses of groundwater circulation, flow paths, and distribution of F- concentrations in each aquifer were conducted. In groundwater, the concentration of fluoride varies from 0.1 to 68.9 mg L−1; in surface water, it ranges from 0.6 to 244.2 mg L−1. Fluoride concentration of 62 % of the water samples analyzed exceeded the 1.5 mg L−1 WHO threshold for fluoride concentration in drinking water. The proposed methodological approach has been demonstrated to be a powerful tool that could be applied in other similar areas.

Studying Hydraulic Interconnections in Low-Permeability Media by Using Bacterial Communities as Natural Tracers

Knowledge about the processes governing subsurface microbial dynamics in and to groundwater represents an important tool for the development of robust, evidence-based policies and strategies to assess the potential impact of contamination sources and for the implementation of appropriate land use and management practices. In this research, we assessed the effectiveness of using microorganisms as natural tracers to analyze subsurface dynamics in a low-permeability system of northern Italy. Microbial communities were investigated through next-generation sequencing of 16S rRNA gene both to study hydraulic interconnections in clayey media and to verify the efficacy of outcropping clayey horizons in protecting groundwater against contamination. During the observation period, a rapid water percolation from the ground surface to the saturated medium was observed, and the mixing between lower-salinity fresh-infiltration waters and higher-salinity groundwater determined the formation of a halocline. This rapid percolation was a driver for the transport of microorganisms from the topsoil to the subsurface, as demonstrated by the presence of soil and rhizosphere bacteria in groundwater. Some of the species detected can carry out important processes such as denitrification or nitrate-reduction, whereas some others are known human pathogens (Legionella pneumophila and Legionella feeleii). These findings could be of utmost importance when studying the evolution of nitrate contamination over space and time in those areas where agricultural, industrial, and civil activities have significantly increased the levels of reactive nitrogen (N) in water bodies but, at the same time, could highlight that groundwater vulnerability of confined or semi-confined aquifers against contamination (both chemical and microbiological) could be higher than expected.

Contribution of Isotopic Techniques in the Hydrological Study of the Aquifers of Ica, Villacuri and Lanchas

Ica Aquifer located at the coastal zone of Ica River Valley, supplies 40% of the water to a number of farms of Ica Region which is one of the most productive valley of Peru that covers an area of 30,000 hectares of area, in which a diverse agricultural product are grown for local and external market. In the last 15 years, water-table of the aquifer was lowering at an elevated rate that concerned to farmers and authorities of the Peruvian Government, so a number of studies was carried out to increase the water supply to the agriculture areas.The main purpose of the study using isotope techniques, was to have a first insight of the hydrodynamics of Ica, Villacuri and Lanchas Aquifers and the possible interconnection between them and with Pisco River. For such purpose, 31 wells, lakes, rivers and springs of Ica and Pisco Basin where sampled during the years 2014 to 2016 both in rain and dry seasons, getting 189 samples for isotope and chemical analysis. The sampling schedule didn’t include rain sampling, instead of it, selected springs were sampled and nearby basin rain data was used.18O,2H and 13C stable isotopes and 3H, 14C radioactive isotopes of the water samples were analyzed in the laboratory of “Isotope Tracer Technologies INC”; the results of the stable isotope analysis confirm the hydraulic interconnection of the three aquifers mentioned above; it also was confirmed that the main source of recharge was provided by Ica River and evidences were found about the contribution of Pisco River in the recharge of Villacuri and Lanchas Aquifers.Analysis of 14C reveals that some wells are overexploited. All the results of 3H analysis were out of range, so it was not useful for the conclusions of the study, and a new sampling of water is required; the reason of this out of range result should be the possible contamination of the samples with no environmental Tritium.

Hidrodinâmica do Sistema Aquífero Cárstico Bambuí, com uso de traçadores corantes, na região de Lagoa Santa, Minas Gerais

A área estudada localiza-se a 30 km a norte de Belo Horizonte e engloba a Área de Proteção Ambiental Carste de Lagoa Santa. A Formação Sete Lagoas é a principal unidade aflorante, configurando uma geomorfologia cárstica diversa, caracterizada por canyons, vales cegos, dolinas e cavernas. Em subsuperfície, uma rede de condutos forma aquíferos cársticos que abrigam importantes reservas hídricas, que vêm sofrendo riscos qualitativos e quantitativos face a acentuada pressão da expansão demográfica e industrial. Empregando-se a técnica de injeção de traçadores corantes, procurou-se estabelecer as interconexões hidráulicas, condições hidrodinâmicas das rotas de fluxo, configurações da recarga, circulação e descarga desses aquíferos. Foram executados dez ensaios quali-quantitativos utilizando Fluoresceína e Rodamina WT. Resultados positivos para interconexões hídricas foram observados em sete ensaios, desvendando-se a proveniência de 68,3%, 13,0%, 70,2%, 41,3% das descargas em quatro surgências. As velocidades médias aparentes variaram de 9,5x10-3 m/s a 4,49x10-2 m/s e de 1,43x10-2 m/s a 6,27x10-2 m/s considerando-se o fator de sinuosidade da rota, o que evidencia a alta velocidade dos fluxos.

Characterization of Mechanisms and Processes Controlling Groundwater Recharge and its Quality in Drought-Prone Region of Central India (Buldhana, Maharashtra) Using Isotope Hydrochemical and End-Member Mixing Modeling

A thorough study on understanding of groundwater recharge sources and mechanisms was attempted by integrating the hydrogeological, geochemical and isotopic information along with groundwater dating and end-member mixing analysis (EMMA). This study was necessitated due to prolonged dryness and unavailability of freshwater in semi arid Deccan trap regions of Central India. In addition, groundwater resources are not characterized well in terms of their geochemical nature and recharge sources. The hydrogeochemical inferences suggest that aquifer I consists of recently recharged water dominated by Ca–Mg–HCO3 facies, while groundwater in aquifer II shows water–rock interaction and ion exchange processes. Presence of agricultural contaminant, nitrate, in both aquifers infers limited hydraulic interconnection, which is supported by unconfined to semi-confined nature of aquifers. Groundwater in both aquifers is unsaturated with respect to carbonate and sulfate minerals indicating lesser water–rock interaction and shorter residence time. This inference is corroborated by tritium age of groundwater (aquifer I: 0.7–2 years old and aquifer II: 2–4.2 years old). Stable water isotopes (δ2H, δ18O) suggest that groundwater is a mixture of rainwater and evaporated water (surface water and irrigation return flow). EMMA analysis indicates three groundwater recharge sources with irrigation return flow being the dominant source compared to others (rainwater and surface waters). A conceptual model depicting groundwater chemistry, recharge and dynamics is prepared based on the inferences.

Boundary condition control on inter-aquifer flow in the subsurface of Berlin (Germany) – new insights from 3-D numerical modelling

Abstract. We investigate the degree of hydraulic interconnection between the different (regional to local) groundwater compartments with respect to the choice of boundary conditions and their impact onto the groundwater safety beneath the urban centre of Berlin, capital city of Germany. To this end, we carry out a systematic study based on 3-D hydrothermal models differing in terms of imposed parametric set-ups of the hydrogeology, as well as different surface forcing with respect to their impact on fresh groundwater production. The study area is part of the Northeast German Basin and consists of a thick sequence (up to 5 km) of differently consolidated sedimentary deposits. This sedimentary succession features a sequence of alternating aquifers (reservoirs) and aquitards which are connected to different degrees, each one depicting a specific composition of its mineralised pore water. The uppermost aquifer system (made up mainly of poorly consolidated siliciclastic rocks) acts as the main freshwater reservoir used for groundwater production by the municipal water supplier. This compartment is incompletely sealed from the brackish to saline aquifers extending at greater depths by a regional clay-enriched aquitard, the Oligocene Rupelian Clay. The latter shows a heterogeneous thickness distribution due to erosion during the latest glacial periods resulting in local discontinuities. This aspect opens to the potential risk of contamination of the drinking water reservoir from mixing with the saline groundwater upconing, locally enhanced by shallow pumping activities. Based on our results and their correlation with available isotopic and chemical analysis of water samples, we demonstrate how hydraulic connection between the different compartments is indeed likely to occur thus supporting the possibility of a contaminant rise from the saline aquifers below through either natural or anthropogenic (pumping) forcing.

THE CHOICE GROUND OF DOWNHOLE STREAM PUMP GEOMETRICAL SIZES

The method of choosing geometric parameters of the well hole pump which ensures its operation in the mode of maximum efficiency is proposed. According to the algorithm developed, the ratio of the diameters of the working nozzle, the mixing chamber and the diffuser of the jet pump, as well as the distance between the nozzle and the speed equalization chamber and the axial dimensions of the flow part elements are regulated. During the process of establishing the required dimensions of the elements of the ejection system, the nature of the free working jet into the mixing chamber of the jet pump is taken into account, which determines the shape and structure of the estimated ratios governing the axial distance between the working nozzle and the resuscitation chamber of the mixing streams. The relationship between the mixing chamber diameters and the working nozzle and the amount of the jet pump coefficient of ejection which ensures its operation with the maximum possible values of the ejection system efficiency is shown. The analytical nature of the establishment of hydraulic interconnections among the elements of the ejection system is complemented by the experience of the practical use of deep jet pumps in the implementation of certain technological processes of construction, operation and repair of oil wells.

Hydrogeological conceptual model of large and complex sedimentary aquifer systems – Central Kalahari Basin

Successful groundwater resources evaluation and management is nowadays typically undertaken using distributed numerical groundwater flow models. Such models largely rely on hydrogeological conceptual models. The conceptual models summarize hydrogeological knowledge of an area to be modelled and thereby providing a framework for numerical model design. In this study, an efficient data integration method for developing hydrogeological conceptual model of the large and hydrogeologically-complex, Central Kalahari Basin (CKB) aquifer system, was undertaken. In that process, suitability of 3-D geological modelling with RockWorks code in iterative combination with standard GIS (ArcGIS) was tested. As a result, six hydrostratigraphic units were identified, their heads and related flow system interdependencies evaluated and hydraulic properties attached. A characteristic feature of the CKB is a thick unsaturated Kalahari Sand Unit (KSU), that restricts the erratic recharge input to <1 mm yr−1 in the centre to about 5–10 mm yr−1 in the eastern fringe. The analysis of the spatial distribution of topological surfaces of the hydrostratigraphic units and hydraulic heads of the aquifers, allowed to identify three flow systems of the three aquifers, Lebung, Ecca and Ghanzi, all three having similar radially-concentric regional groundwater flow patterns directed towards discharge area of Makgadikgadi Pans. That pattern similarity is likely due to various hydraulic interconnections, direct or through aquitard leakages, and also due to the presence of the overlying unconfined, surficial KSU, hydraulically connected with all the three aquifers, redistributing recharge into them. The proposed 3-D geological modelling with RockWorks, turned to be vital and efficient in developing hydrogeological conceptual model of a large and complex multi-layered aquifer systems. Its strength is in simplicity of operation, in conjunctive, iterative use with other software such as standard GIS and in flexibility to interface with numerical groundwater model. As a result of conceptual modelling, fully 3-d, 6 layer numerical model, with shallow, variably-saturated, unconfined layer is finally recommended as a transition from conceptual into numerical model of the CKB.

The Integrated Management of Water Crises: The Case for Long-Range Hydraulic Interconnections

The Integrated Management of Water Crises: The Case for Long-Range Hydraulic Interconnections

Upstream Hydraulic Interconnection Study of Gunungkidul Karst Area Underground Rivers

AbstractHydraulic interconnection of Jomblangan cave (Petung) with other caves and water discharges in Gunungkidul karst area has been investigated using tracer techniques and variationof stable isotopes and hydrochemical data interpretation from water samples near the cave. Many studies related to the interconnections of underground rivers around Gunungkidul Karst area have been conducted, most of them, however, focused on the area around Bribin and Seropan caves. This is because of the development activites of microhydro turbines to lift the water from underground river were still focused around Bribin and Seropan caves. Petung cave, located in the north of Bribin and Seropan caves, was believed to be one of the caves at the upstream river system of Bribin and Seropan, however, there is no evidence yet of the hydraulic interconnection between Petung cave with either Bribin or Seropan caves. The results of tracer technique at the current study showed that there was no hydraulic interconnection between Petung cave with either Bribin and Seropan caves.On the other hand, the study showed an indication of a direct flow from Petung cave to Sriti and Beton springs. The travel times from Petung to Sriti and Beton springs were found to be around 2 and 10 hours, respectively. This finding is also in agreement with the results of chemical and stable isotopes analysis from the research location. AbstrakPenelitian keterhubungan Gua Jomblangan (Petung) dengan gua lainnya dan keluaran air di sekitar daerah karst Gunungkidul telah dilakukan dengan menggunakan teknik perunut dan variasi kandungan isotop stabil serta hidrokimia sampel air di sekitar gua. Penelitian yang berkaitan dengan keterhubungan antara sistim aliran bawah tanah di sekitar daerah karst Gunungkidul telah banyak dilakukan, namun sebagian besar dari penelitian tersebut hanya berpusat pada gua di sekitar Bribin dan Seropan. Hal ini terjadi karena kegiatan pembangunan turbin-turbin mikrohidro untuk mengangkat air dari sungai bawah permukaan tanah masih terfokus di daerah gua Bribin dan Seropan. Gua Petung, yang berada di sebelah utara gua Bribin dan Seropan, dipercaya merupakan salah satu gua yang berada di hulu sistim sungai bawah tanah Bribin dan Seropan, namun, sampai sekarang belum ada bukti keterhubungan hidrolika antara gua Petung dengan gua Bribin maupun dengan gua Seropan.Hasil uji perunut dalam penelitian ini menunjukkan bahwa aliran air bawah tanah di gua Petung tidak berhubungan langsung dengan aliran bawah tanah di gua Bribin maupun di gua Seropan. Sebaliknya, hasil penelitian ini menunjukkan adanya aliran langsung dari gua Petung ke mata air Sriti dan Beton. Waktu tempuh yang dibutuhkan dari gua Petung ke mata air Sriti adalah sekitar 2 jam dan ke mata air Beton adalah sekitar 10 jam. Temuan ini sangat bersesuaian dengan hasil analisis kimia air dan isotop stabil dari lokasi penelitian.

Hybrid heating system for increased energy efficiency and flexible control of low temperature heat

This study presents the evaluation of functionality and potential of a hybrid heating system (H2S) prototype. This technology is designed for retrofitting thermal treatment plants to use hot water (HW) and steam in controlled ratios. In the food industry, steam with a temperature above 140 °C usually indirectly supplies the thermal production processes, but most of them only require temperatures below 100 °C. Total site heat integration is applied on a cheese and whey powder plant to show the potential for low-temperature heat (below 100 °C) that could be supplied more appropriately by hot water cogeneration, heat recovery and heat pumps. These low-temperature heat sources can only be combined with the rigid steam system if the demand structure is changed to a hybrid use of HW and steam. The H2S increases the energy efficiency and flexibility by integrating low-temperature heat and responding to sudden changes in the demand and supply structure, like demand response strategies on intermittent renewable energies and the changing availability of HW and steam. The technical implementation is realised by a hydraulic interconnection of heat exchangers and valves. A smart control algorithm acutely determines the share of HW and steam. Prerequisite for functional verification on a laboratory scale is a hardware-in-the-loop (HIL) testbed, in which load profiles and relevant process parameters are passed in real time between hardware components and simulation. The results show that the H2S is a feasible solution for maintaining product quality and safety while also increasing energy efficiency and energy flexibility.

A Fully Coupled Model for Hydraulic-Fracture Growth During Multiwell-Fracturing Treatments: Enhancing Fracture Complexity

Summary Multiwell-completion techniques, such as sequential fracturing, zipper fracturing, and simultaneous fracturing, have been proposed to improve fracture complexity and connectivity. Critical geomechanics behind the multiwell-fracturing techniques include pore-pressure propagation, cooling stress, tip-induced shear stress, and reversal of stress anisotropy. To optimize multiwell-fracturing treatments, we numerically investigated fracture growth from the perspective of thermo/hydromechanical (THM) coupling. The coupled geomechanics and fluid-heat-flow model is derived from a mixed finite-element (FE) and finite-volume (FV) method, which is capable of simulating multifracture growth in heterogeneous reservoirs. In this study, both hydraulic-fracture (HF) propagation and natural-fracture (NF) reactivation in opening or shearing patterns were taken into account. Particularly, an elastoplastic fracture constitutive model was adopted to predict permanent enhancement of fracture aperture. The effects of perforation-cluster spacing, well spacing, and the fracturing sequence of multiwell completion upon fracture complexity were studied, where the total hydraulically fractured area was treated as the primary indicator of HF effectiveness. By numerical parametric studies, we determined four findings. First, there is an optimal cluster spacing for maximizing the total fracture area for a stage with a given length. Cluster spacing mainly affects stress distribution during HF, which subsequently affects the path of newly created fracture propagation and crossing behaviors (i.e., crossing, arresting, or offsetting). Second, suitable well spacing should be chosen carefully to avoid the hydraulic interconnection between the tip-to-tip stages, as well as to make use of tip-induced shear stresses. Third, the fracturing sequence for multiwell completion is of critical importance. Among three multiwell-completion schemes (i.e., sequential, zipper, and simultaneous fracturing), the zipper-fracturing technique achieves the best fracturing effectiveness for this case study. Fourth, the effect of stress perturbation on NFs can be quite different, depending on the position relative to the created stimulated reservoir volume (SRV). The coupled model significantly improves our understanding of multiwell-fracturing treatments and then provides us with a means to optimize the multiwell completion, enhancing fracture complexity to effectively improve productivity.

The scaling of the hydraulic architecture in poplar leaves.

Although much is known about the hydraulics of xylem, the hydraulic interconnectivity and dimensional scaling of phloem with respect to xylem in leaves has not been adequately studied to test alternative hydraulic architectural rules such as da Vinci's rule or Murray's rule, or physiological models such as Münch's Pressure Flow hypothesis. Using confocal and electron microscopy as well as mathematical analyses, we examined the hydraulic architecture of the mature leaves of the model species Populus tremula×alba across all seven hierarchical orders of the vascular branching. We show that: phloem and xylem conductive areas increase from minor to major veins; the sum of the conductive areas for each vein order increases exponentially from major to minor veins; the volume of individual sieve tube and vessel members increases from minor to major veins; and phloem conductive area scales isometrically with respect to xylem area across all vein orders. The application of first principles to our data shows that conductive areas scale according to da Vinci's rule and not according to Murray's rule, and that the phloem network in poplar leaves can generate the pressure gradient envisioned in Münch's hypothesis.

Hydrologic interconnection between the volcanic aquifer and springs, Lake Tana basin on the Upper Blue Nile

Hydrochemical and stable isotope (δ18O, δ2H) data were used to identify the recharge sources of major springs and the hydraulic interconnection between the volcanic aquifer and springs in the Gilgel Abay catchment and adjacent areas. The hydrochemical data analysis showed that all water samples of springs and shallow wells have freshwater chemistry, CaHCO3 to CaMgHCO3 types. This is mainly controlled by dissolution/hydrolysis of silicate minerals. The analyzed stable isotope data indicate that springs water, except Dengel Mesk, Kurt Bahir and Bility springs, and well waters, except Dangila well, fall close to the LMWL. This clearly shows that the infiltrated rainwater did not undergo much evaporation and δ18O values for spring water and groundwater are nearly equal to the value of Ethiopian summer rainfall, which is −2.5‰. Therefore, generally both stable isotope and hydrochemical data show the recharge source to springs and shallow groundwater is primarily from precipitation. Furthermore, data suggest that rock-water interaction has remained relatively limited, pointing to relatively short residence times, and local recharge rather than regional recharge.