Water Flow System Research Articles

Efficient Cooling System Using Electrocaloric Effect

The electrocaloric effect in thin films of an electrocaloric material has the potential to be used for efficient cooling systems for high power electronic devices. We numerically calculated the effect of parameters in electrocaloric refrigeration with a thermal switch of fluid motion on the thermal performance. The system of changing air and water flow with the pulse generation of cold energy increased the heat transfer efficiency to 67% at a frequency of 5 Hz. The optimum time delay of water flow to increase the heat transfer efficiency was zero at low frequency and became half of the time period to change heat for a high frequency of 100 Hz. When the heat transfer efficiency was high, the final temperature change in water flow was not the maximum temperature change.

Efficient Interaction between Energy Demand Surplus Heat, Cooling and Thermal Storage

The purpose of the research was to examine the savings potential and verify how to reduce the energy consumption in new hospitals by about 50%. Our results are also very relevant in other buildings complex with surplus heating, cooling and thermal storage.Conversion and utilization of surplus heat sources represent well known technologies and are under constant development. In large building complexes there is a potential for coordinated production, storage, and distribution of energy. Heat pump, chiller and thermal storage technologies enable re-use of surplus heat/cool energy throughout the year. Energy supply and demand are typically modelled with separate tools and timescales.Through our study new methods are developed for operation of interacting simulating models. These methods provide tools to step into optimization of combinations of integrated energy systems. The main issues focus on hydraulic water flow and storage systems as a basis. The layout is important not only with regards to utilize the energy quality, i.e. the temperature. In addition, control strategies are shown to have a highly relevant impact on the possible savings. Some details of new hydraulic layout and control design will be described and discussed in the paper. Both in combination with heating, cooling and storage system.Our research indicates that it is possible to save between 20-50% of the energy consumption with optimizing the technical installations in Oslo area.Another benefit of integrated thermal modelling is to reduce the risk of permafrost in ground source heat pump installations. This risk is relevant for large buildings in northern Norway, at annual mean temperatures are below 0̊C.This paper shows how integrated simulation and design can be used to avoid permafrost.

Floods in Jeddah, Saudi Arabia: Unusual Phenomenon and Huge Losses. What Prognoses

Situated in the South-West of Saudi Arabia, Jeddah is the biggest port city in the red sea and the kingdom's second city after Riadth. Jeddah has a population of 3500000 inhabitants. It benefits from many economic assets due mainly to its being a transit point toward the holly sites of Islam. Despite being characterized by a dry climate, by poor rain fall levels, by deficits of rain compared to evaporation, and by the irregularity of water flow systems along with the functional degradation of its hydraulic networks, Jeddah underwent many unexpected floods- three big ones in 2009, 2010, and 2011. The human tolls as well as the material losses were huge: hundreds dead, thousands of damaged buildings which were built on slopes or close to river beds with legal permits. Such floods were studied by local and national authorities as well as scholars in order find adequate solutions.It is within this framework and with modelization statistics and cartographic analyses in mind that we will attempt to understand what caused such floods: –Natural causes (geo-morphological specifics, climate change, intensive rainfall), –Human causes: lack of hazard culture, urban extension and planification, and the absence of viable strategies of prevention

Water Purification in Micromagnetofluidic Devices: Mixing in MHD Micromixers

This contribution addresses a possible solution for water purification from heavy metals by magnetic nanoparticles in microfluidic water flow systems. In this technique, the most important component is the micromixer while efficient mixing and particle driving is achieved by external magnetic fields. For the simulation of water flow and nanoparticles, Computational Fluid Dynamics methods are used. The 2D and 3D Navier-Stokes equations are solved for the flow field while trajectories of the magnetic nanoparticles are simulated by the use of a Lagrangian method. Compared to traditional techniques, this method is expected to succeed chemical speed and increased water purification times.

Joint estimation of hydraulic conductivities of two sand samples in a W-tube system with a bi-exponential response

The motivation for this paper is the practical problem of interpreting bi-exponential rate-of-rise curves that are observed during many field piezometric tests. In the authors' previous study, a laboratory W-tube system of water flow through two samples of sand was introduced with an adequate mathematical model. The desired bi-exponential character of water flow was obtained by placing two different samples of sand in separate but connected columns. In the present paper, a so-called inverse problem is solved. The optimization procedure is applied in order to jointly estimate a pair of hydraulic conductivity values based on experimentally recorded bi-exponential rate-of-rise curves. The obtained values of hydraulic conductivities are presented and compared to the values determined from independent constant-head permeability tests conducted for the analyzed sands. The results of this identification procedure varied in accuracy. The mean percent errors between the hydraulic conductivity values measured jointly and independently for the analyzed experimental series were in the range of 8.8 to 37.2%. The discussion presents the restrictions of this interpretational method and suggests further modeling plans.

Bioaccumulation of Metals Arsenic, Cadmium, and Lead in Zooplankton and Fishes from the Tula River Watershed, Mexico

The Tula River watershed is a water flow system that runs from the State of Mexico to the south-central part of Hidalgo State in Mexico that includes the Mezquital Valley which was originally a semiarid zone and now is an important agricultural region. We studied the River Tula watershed regarding biological, chemical, and physical parameters, describing the zooplankton species list, and the levels of five metals: arsenic, cadmium, copper, lead, and zinc, in sediments, elutriates, water column, and bioaccumulation in tilapia (Oreochromis nilotica), and some zooplanktonic species using atomic absorption. Arsenic, cadmium, and lead are present in the water column in small concentrations of different reservoirs of the Tula River watershed. Concentration of these three metals in elutriates and sediments are higher than levels in water column. The effects of the presence of these three metals in the water column, elutriates, and sediments include the following: (a) Levels of lead in muscles of tilapia make this species unsafe for human consumption, and (b) arsenic, cadmium, and lead are bioaccumulated in several zooplanktonic species. We discuss these results in the context of (a) bioaccumulation through trophic levels and (b) international and Mexican national standards regarding safe levels of contaminants in fish tissues for human consumption.

Impact of heterogeneous permeability distribution on the groundwater flow systems of a small sedimentary basin

Ground water flow systems of shallow sedimentary basins are studied in general by analyzing the fluid dynamics at the real world example of the Thuringian Basin. The impact of the permeability distribution and density differences on the flow velocity pattern, the salt concentration, and the temperature distribution is quantified by means of transient coupled simulations of fluid flow, heat, and mass transport processes. Simulations are performed with different permeabilities in the sedimentary layering and heterogeneous permeability distributions as well as with a non-constant fluid density. Three characteristic numbers are useful to describe the effects of permeability on the development of flow systems and subsurface transport: the relation of permeability between aquiclude and aquifer, the variance, and the correlation length of the log-normal permeability distribution. Density dependent flow due to temperature or concentration gradients is of minor importance for the distribution of the flow systems, but can lead to increased mixing dissolution of salt. Thermal convection is in general not present. The dominant driver of groundwater flow is the topography in combination with the permeability distribution. The results obtained for the Thuringian Basin give general insights into the dynamics of a small sedimentary basin due to the representative character of the basin structure as well as the transferability of the settings to other small sedimentary basins.

Large-Scale Particle Image Velocimetry From an Unmanned Aerial Vehicle

Large-scale particle image velocimetry (LSPIV) enables nonintrusive and continuous characterization of surface flow velocities in natural watersheds. However, current LSPIV implementations are based on fixed cameras that only allow for surface flow monitoring at a limited number of locations on the water stream. This paper seeks to leverage the growing field of unmanned aerial vehicles to transform LSPIV practice, by enabling rapid characterization of large water flow systems in areas that may be difficult to access by human operators. Toward this aim, a lightweight and low cost quadrotor is developed to host a digital acquisition system for LSPIV. A gimbal is realized in house to maintain the camera lens orthogonal with respect to the water surface, thus preventing image orthorectification. Field experiments demonstrate that the vehicle is able to stably hover above an area of $1 \times 1\, {\rm m^2}$ for $4$ min with a payload of $532\, {\rm g}$ . The feasibility of quadrotor-based LSPIV is demonstrated through tests in an outdoor laboratory setting and over a natural stream.

Dense water flow and carbonate system in the southern Adriatic: A focus on the 2012 event

The active deep overturning circulation of the Mediterranean is emerging as one of the most effective mechanisms in transporting the atmospheric imprint on the carbon cycle to the interior of the basin. There is growing evidence that sites of dense water formation over the continental shelf, such as the Northern Adriatic Sea, play a key role in this process. Nevertheless, little is known about the inorganic carbon chemistry of the Adriatic sea, and CO2 absorption and its fate.The winter of 2012 experienced peculiar meteorological conditions with an extended period of cold weather with strong winds that triggered, in February, a massive formation of an extremely cold and dense (potential density anomaly >30.00kgm−3) Northern Adriatic Dense Water (NAdDW) water mass. This event provided a unique opportunity to study this process at sub-basin scale taking into account CO2 adsorption within the NAdDW source area (the Gulf of Trieste in the northern Adriatic), and its spreading over the shelf and into the Southern Adriatic Pit.The northern Adriatic and the Gulf of Trieste, during winter, act as a CO2 sink. The average air-sea CO2 flux of 60mmolm−2 d−1 estimated during the exceptional 2012 event was at least 3 times higher than the flux measured in winter 2008 when dense water was produced through the same mechanism but under less extreme conditions. In winter 2012, absorbed CO2 resulted in the decrease of pHT25 down to 7.907 (− 0.034 pHT units) and the strong evaporation induced by wind-increased total alkalinity (TA) to 2673 (+ 16μmolkg−1).Following its formation in the North, the NAdDW plume entering the Southern Adriatic, observed in March 2012, exhibited significantly modified values. The plume was characterized by colder temperature (~ 10°C), lower pHT25 (7.947 pHT units) and higher alkalinity (2635μmolkg−1) than the surrounding water masses along the western Adriatic shelf. However, the signal of atmospheric CO2 enrichment was weaker than in the northern Adriatic source region, as well as positive apparent oxygen utilization (AOU) values (~ 20μmolkg−1) were recorded. This is suggestive of oxygen consumption in the water mass.Observed changes in both physical and biogeochemical properties were similar to those observed in 2008, suggesting that mixing with Levantine Intermediate Waters (LIW) was the main driver modulating the changes of AOU and inorganic carbon chemistry in both winters. The rising of pHT25 and AOU due to the mixing indicates that NAdDW, at its origin, was richer in atmospheric CO2 than the LIW was, thus confirming the relevance of the Northern Adriatic Sea for CO2 adsorption.The study provides the first characterization of inorganic carbon chemistry, including carbonate minerals saturation states (ΩAr and ΩCa), in the bottom waters both on the slope and along the expected pathways of dense water cascading in the Adriatic Sea. Therefore, it can represent a baseline to improve the knowledge on the acidification process and impacts as well as being useful for comparison with other benthic environments.

Synthesis of alkali niobate K1−xNaxNbO3 nanoparticles using a supercritical water flow system

Alkali niobate, K1−xNaxNbO3, nanoparticles (ca. 50–60nm) were continuously synthesized from Nb-sol and NaOH/KOH solutions with a supercritical water flow system. The syntheses were carried out at temperatures from 400 to 480°C, at pressures from 25 to 30MPa, and at reaction times from 0.1 to 8.3s. X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy–energy dispersion spectroscopy (SEM–EDS) techniques were used to characterize the samples. Single phase KNbO3 was obtained at 480°C and 25MPa at an initial K/Nb molar ratio of 15. The K/Nb molar ratio of the products increased with an increase in the reaction time. For NaNbO3, single phase product was formed under supercritical water conditions irrespective of the temperature and pressure. The K1−xNaxNbO3 nanoparticles were synthesized at 480°C and 25MPa for varying Na/K concentrations. Single phase K0.5Na0.5NbO3 was obtained at an initial Na/K molar ratio of 0.25. To form the perovskite structure, the rearrangement of NbO6 units with alkaline ions is required. The rearrangement proceeds more rapidly with Na+ ions than with K+ ions probably due to the smaller ionic radius of Na+. Therefore, formation of K0.5Na0.5NbO3 was achieved at the excess amount of K+ ions than Na+ ions.

Development of a setup to enable stable and accurate flow conditions for membrane biofouling studies

Systematic laboratory studies on membrane biofouling require experimental conditions that are well defined and representative for practice. Hydrodynamics and flow rate variations affect biofilm formation, morphology, and detachment and impacts on membrane performance parameters such as feed channel pressure drop. There is a suite of available monitors to study biofouling, but systems to operate monitors have not been well designed to achieve an accurate, constant water flow required for a reliable determination of biomass accumulation and feed channel pressure drop increase. Studies were done with membrane fouling simulators operated in parallel with manual and automated flow control, with and without dosage of a biodegradable substrate to the feedwater to enhance biofouling rate. High flow rate variations were observed for the manual water flow system (up to ≈9%) compared to the automatic flow control system (<1%). The flow rate variation in the manual system was strongly increased by biofilm accumulation, while the automatic system maintained an accurate and constant water flow in the monitor. The flow rate influences the biofilm accumulation and the impact of accumulated biofilm on membrane performance. The effect of the same amount of accumulated biomass on the pressure drop increase was related to the linear flow velocity. Stable and accurate feedwater flow rates are essential for biofouling studies in well-defined conditions in membrane systems.

Automated Scalable Heat Shock Modification for Standard Aquatic Housing Systems.

Heat shock is a common technique for inducible gene expression system in a variety of organisms. Heat shock treatment of adult zebrafish is more involved and generally consists of manually transferring fish between housing rack tanks and preheated water tanks or the use of timed heaters in stand-alone aquaria. To avoid excessive fish handling and to take advantage of the continuous flow of a standard housing rack, proposed modifications consisted of installing an aquarium heater inside each tank, manually setting the heater to reach heat shocking temperatures (> 37°C) and, after that, testing that every tank responded equally. To address the limitations in the existing systems, we developed a novel modification of standard zebrafish housing racks to perform heat shock treatment in conditions of continuous water flow. By adding an extra manifold to the housing rack and connecting it to a recirculating bath to create a parallel water flow system, we can increase the temperature from standard conditions (28.5°C) to heat shock conditions with high precision (38.0-38.3°C, mean ± SD = 38.1°C ± 0.14°C) and minimal variation among experimental tanks (coefficient of variation [CV] = 0.04%). This means that there is virtually no need for laborious pretreatment calibrations or continuous adjustments to minimize intertank variation. To test the effectiveness of our design, we utilized this system to induce enhanced green fluorescent protein (EGFP) expression in hsp70-EGFP fish and performed a fin regeneration experiment with hsp70l:dnfgfr1-EGFP fish to confirm that heat-induced gene expression reached physiological levels. In summary, our newly described aquatic heat shock system minimizes effort during heat shock experiments, while ensuring the best water quality and fish welfare and facilitating large heat shock settings or the use of multiple transgenic lines for both research and teaching experiments.

Method of coupling 1-D unsaturated flow with 3-D saturated flow on large scale

A coupled unsaturated-saturated water flow numerical model was developed. The water flow in the unsaturated zone is considered the one-dimensional vertical flow, which changes in the horizontal direction according to the groundwater table and the atmospheric boundary conditions. The groundwater flow is treated as the three-dimensional water flow. The recharge flux to groundwater from soil water is considered the bottom flux for the numerical simulation in the unsaturated zone, and the upper flux for the groundwater simulation. It connects and unites the two separated water flow systems. The soil water equation is solved based on the assumed groundwater table and the subsequent predicted recharge flux. Then, the groundwater equation is solved with the predicted recharge flux as the upper boundary condition. Iteration continues until the discrepancy between the assumed and calculated groundwater nodal heads have a certain accuracy. Illustrative examples with different water flow scenarios regarding the Dirichlet boundary condition, the Neumann boundary condition, the atmospheric boundary condition, and the source or sink term were calculated by the coupled model. The results are compared with those of other models, including Hydrus-1D, SWMS-2D, and FEFLOW, which demonstrate that the coupled model is effective and accurate and can significantly reduce the computational time for the large number of nodes in saturated-unsaturated water flow simulation.

The soil–water flow system beneath a cotton field in arid north-west China, serviced by mulched drip irrigation using brackish water

A field experiment was carried out in southern Xinjiang, China, to reveal soil-water flow pattern beneath a combined plastic-mulch (film) and drip-irrigation system using brackish water. The soil-water flow system (SWFS) was characterized from soil surface to the water table based on observed spatio-temporal distribution of total soil-water potential, water content and electric conductivity. Root suction provided a strong inner sink. The results indicated that SWFS determined the soil salinity and moisture distribution. Drip-irrigation events could leach excess salts from the root zone and provide soil conditions with a tolerable salinity level that supports the growth of cotton. High-salinity strips were formed along the wetting front and at the bare soil surface. Hydrogeology conditions, irrigation regime, climate, plant growth and use of mulch would affect potential sources and sinks, boundary conditions and the size of the SWFS. At depth 0–60 cm, the soil salinity at the end of the irrigation season was 1.9 times that at the beginning. Beneath the mulch cover, the soil-water content in the ‘wide rows’ zone (55 cm between the two rows with no drip line) was higher than that in the ‘narrow rows’ zone (15 cm between the two rows with a drip line) due to the strong root-water uptake. The downward water flow below the divergent curved surface of zero flux before irrigation, and the water-table fluctuation with irrigation events, indicated that excessive irrigation occurred.

Survival and Growth Rate of Larval Ompok pabda (Hamilton-Buchanan, 1822) of Tripura, India: Related to Efficient Feed

Mass larval population of the captive bred stock of Ompok pabda was reared successfully for the first time in India. In order to evaluate the increase of survival and growth rate of the larvae, an ex-situ experiment was continued for about 28 days with the supply of different types of food by maintaining the water quality at standard level (water velocity = 1.01 − 1.26 m/s, temperature = 24.0 − 29.5 °C, DO2 = 4.8 − 6.4 ppm, CO2 = 1.2 − 2.9 ppm, pH = 7.3 − 8.5, DOM = 0.94 − 2.23 ppm and HCO3 = 120 − 176 ppm) under a specific cycling water-flow system to the larvae. The experiment revealed significantly higher (91.72 %, r = 0.987, P < 0.01) survival and growth rate of the larvae, when zooplankton along with tubifex were offered as feed. The impact of other feeds such as tubifex (72.28 %, r = 0.822, P < 0.05), zooplankton (73.42 %, r = 0.762, P < 0.05), egg custard (56.80 %) and compound feed (34.28 %) were gradually less. Specific growth rate (SGR = 6.39 ± 0.58) was also highest in the larvae fed with zooplankton plus tubifex as feed. The said feed was also effective to increase the body weight at a maximum level. Therefore, the feed prepared through the use of mass cultured zooplankton and tubifex seems to be suitable under specific rearing system to promote aquaculture.

CO2 enrichment alters diurnal stem radius fluctuations of 36‐yr‐old Larix decidua growing at the alpine tree line

To understand how trees at high elevations might use water differently in the future, we investigated the effects of CO2 enrichment and soil warming (separately and combined) on the water relations of Larix decidua growing at the tree line in the Swiss Alps. We assessed diurnal stem radius fluctuations using point dendrometers and applied a hydraulic plant model using microclimate and soil water potential data as inputs. Trees exposed to CO2 enrichment for 9 yr showed smaller diurnal stem radius contractions (by 46 ± 16%) and expansions (42 ± 16%) compared with trees exposed to ambient CO2 . Additionally, there was a delay in the timing of daily maximum (40 ± 12 min) and minimum (63 ± 14 min) radius values for trees growing under elevated CO2 . Parameters optimized with the hydraulic model suggested that CO2 -enriched trees had an increased flow resistance between the xylem and bark, representing a more buffered water supply system. Soil warming did not alter diurnal fluctuation dynamics or the CO2 response. Elevated CO2 altered the hydraulic water flow and storage system within L. decidua trees, which might have contributed to enhanced growth during 9 yr of CO2 enrichment and could ultimately influence the future competitive ability of this key tree-line species.

Review of embryo-larval assay of the mussel Perna perna (L.)

The objective of this work was to review the protocol of the mussel Perna perna embryo-larval test and suggest standardization of the induction technique, exposing time and effect observed in larvae at the end of the experiment. To meet the objectives were employed different physical and chemical methods to accelerate the release of gametes and the success of this release was compared to the index condition of the organisms. Ecotoxicological tests were also performed using the metals cadmium, lead, zinc, copper, chromium and the detergent sodium dodecyl sulfite (SDS) to assess the exposure time and morphological types of effects and their influence on estimates of Median Effective Concentration (EC50). The most efficient induction method to stimulate the release of gametes was the continuous flow system of sea water, but it had a close relationship with the maturation of organisms. It was observed that the short term embryo-larval test can be executed in 24 hours since protracted larvae are considered normal as observed in control flasks experiments. Finally, embryo-larval test of the P. perna showed sensitivity in the same order of magnitude as compared to Lytechinus variegatus the main species of sea urchin commonly used in marine chronic tests in Brazil.

Ground Water Contamination of the Coal Gangue Leachate of Sandy Base Field in Erdos - On the Case of the Coal Waste Field of Daliu Tower Mine Area

Based on the hydro-geological survey, sampling analysis and combined with ground water flow systems theory, the work studied coal gangue leachate of a typical sandy base coal waste field in Erdos on ground water environmental impact. The results showed that pile of coal waste change the original characteristics of ground water flow systems, coal waste field from ground water discharge areas change into the runoff area, the bottom of Gangue heap immersion in ground water long term, the toxic and hazardous substances released and spread to the downstream by ground water runoff. Chromium, arsenic, fluoride, sulfateradical, copper, zinc, nickel, manganese and other pollution factors in the downstream ground water of gangue field and surface outlet is much higher than background value, where concentration of arsenic and NO3–N is 1.013mg / l and 31.2 mg / l, respectively higher than the background value which is 148 and 3 times.

Analysis on Issues of Variable Flow Water System

Variable flow water system has played an important role in the field of energy saving with the Electronic Variable Frequency Drive (VFD) widely used in practical projects. How to control the frequency converter to work properly is an essential issue which we must first emphatically solve. The control technology of frequency converter is closely related to characteristics of pumps. Based on the mathmatical a model of pumps with or without inverters, the article discusses some issues in detail, such as inverters configuration, flow rate regulation and overload. These are key issues of control technology of variable flow water system. For those multiple-pump water systems, the engineers may select synchronous frequency conversion control technology or Add-Sub pumps control technology to achieve the maximum energy-saving benefits. DOI: http://dx.doi.org/10.11591/telkomnika.v11i9.3294

A theory of reverse engineering and its application to Boolean systems

To reverse engineer a system is to infer how its underlying mechanism works. This paper presents a theory of the process, which postulates that individuals rely on an initial strategy of either focusing on the outputs of a system one by one, or on the components of the system one by one. They then try to assemble the system guided by both local and global constraints. The theory predicts that three main factors should affect the difficulty of reverse engineering: the number of variable components in the system, the number of their settings that yield an output, and, most importantly, the interdependence of components on one another in yielding outputs. Five experiments corroborated these predictions, using a test bed of electric light circuits and water-flow systems based on Boolean logic.