Low Water Flow Rates Research Articles

BioMOF@PAN Mixed Matrix Membranes as Fast and Efficient Adsorbing Materials for Multiple Heavy Metals' Removal.

Heavy metal ions are a common source of water pollution. In this study, two novel membranes with biobased metal-organic frameworks (BioMOFs) embedded in a polyacrylonitrile matrix with tailored porosity were prepared via nonsolvent induced phase separation methods and designed to efficiently adsorb heavy metal ions from oligomineral water. Under optimized preparation conditions, stable membranes with high MOF loading up to 50 wt % and a cocontinuous sponge-like morphology and a high water permeability of 50-60 L m-2 h-1 bar-1 were obtained. The tortuous flow path in combination with a low water flow rate guarantees maximum contact time between the fluid and the MOFs, and thus a high heavy metal capture efficiency in a single pass. The performances of these BioMOF@PAN membranes were investigated in the dynamic regime for the simultaneous removal of Pb2+, Cd2+, and Hg2+ heavy metals from aqueous environments in the presence of common interfering ions. The new composite adsorbing membranes are capable of reducing the concentration of heavy metal pollutants in a single pass and at much higher efficiency than previously reported membranes. The enhanced performance of the mixed matrix membranes is attributed to the presence of multiple recognition sites which densely decorate the BioMOF channels: (i) the thioether groups, deriving from the S-methyl-l-cysteine and (S)-methionine amino acid residues, able to recognize and capture Pb2+ and Hg2+ ions and (ii) the oxygen atoms of the oxamate moieties, which preferentially interact with Cd2+ ions, as revealed by single crystal X-ray diffraction. The flexibility of the pore environments allows these sites to work synergically for the simultaneous capture of different metal ions. The stability of the membranes for a potential regeneration process, a key-factor for the effective feasibility of the process in real life applications, was also evaluated and confirmed less than 1% capacity loss in each cycle.

Thermal Stratification Characteristics of Storage Tanks on Solar Water Heater Inserted with Latent Heat Material

As a latent heat medium, phase change material (PCM) can be applied to heat storage for solar water heaters (SWH). The method used to place PCM is to put it in a capsule. Thermal stratification is critical in generating SWH thermal efficiency. Installation of horizontal capsules in the tank has no known effect on thermal stratification. This paper aims to study the thermal stratification in active-type SWH incorporating PCM. A cylindrical capsule containing the PCM was placed inside the tank. The thermocouple was installed on both the water and PCM sides. The charging process was conducted indoors, and the water flow rate varied from 1, 2, and 3 LPM. Water temperature data for each variation was analyzed to evaluate the thermal stratification. Richardson number analysis proved that thermal stratification was formed in all water flow rates. It was found that a low water flow rate results in high thermal stratification.

Experimental study on flow characteristics in a new separator

The confined multiphase swirling flow characteristics were studied in the presence of a new bluff body for gas/liquid separation. It is a hollow cylinder with a tapered front. The flow visualization was performed using High Speed Camera. The gas-to-liquid ratio was controlled by manipulating the air and water flow rates in the flow loop. Based on previous studies, the generated air core exhibits different regimes with stable and unstable regions along the pipe axis. The proposed bluff body should be placed with the stable region to avoid the loss of separation efficiency due to the oscillations of the air core. Three flow regimes were considered based on the water flow rate. At the low water flow rate, the air core is thinner and breaks down a few centimeters upstream of the bluff body. The generated bubbles are sucked inside the bluff body. Increasing the air flow rates causes the air core to get closer to the bluff body until reaching it completely and might enlarge exceeding the bluff body diameter. For all the cases considered, the air core is wavy with highly instable diameter and length. When increasing the water flow rate, a more stable air core is formed closer to the bluff body. The high-water flow rate appears to be necessary to stabilize the air core and reach flow regimes favorable for an efficient separation through both the annular space and the internal passage.

TapBoost - the design for manufacture of a low voltage water pump to boost the poor domestic water flow rate

ABSTRACT The main aim of this research is to increase a low water flow rate of 1 l/m up to a minimum of 6 l/m using a TapBoost pump. This pump will be used to support poor domestic flow rates in the UK & ROI. TapBoost was developed without the need for mechanical seals by using wet rotor technology making it the most efficient water boosting pump in Salamander’s pump range. The various stages of design, testing and development of the TapBoost pump are reported in this paper. TapBoost is an inexpensive solution to improve the water flow rate given from a trickling single outlet anywhere in a domestic setting. TapBoost has been specially designed to be easily installed onto any existing or new water mains pipework. The main conclusions are as follows: i) the TapBoost was successfully designed, manufactured, tested and launched in March 2022, meeting the specification requirements given by Salamander Pumps to develop and launch this new product, ii) The results showed that the pump delivers a boosted water flow rate of 6.75 l/m compared to the original water flow rate, without the use of the pump, of just 1 l/m, iii) The performance of the TapBoost is better than the leading competitor in the market.

Liquid-gas heat transfer characteristics of near isothermal compressed air energy storage based on Spray Injection

Isothermal compressed air energy storage (I-CAES) could achieve high roundtrip efficiency (RTE) with low carbon emissions. Heat transfer enhancement is the key to achieve I-CAES, thus the liquid-gas heat transfer characteristics of near I-CAES system based on spray injection was analyzed in this paper. The liquid-gas heat transfer model and thermodynamic model were established and the effects of design variables on heat transfer rate and energy efficiency were analyzed. The results showed that spray injection can produce considerable heat transfer capacity and effectively suppress air temperature change, but spray injection at initial compression stage will not bring much heat transfer enhancement. Increasing spray flow rate shifts the dominant heat transfer contribution from water bulk to spray heat transfer and increases total heat transfer rate and RTE, however the increase effect of spray injection is more obvious in small-scale CAES. Low water flow rate and large working cylinder volume are recommended to achieve slow compression and expansion processes with enough liquid-gas heat transfer duration, realizing near I-CAES with high RTE. High air storage pressure increases heat transfer rate, but deviates CAES from isothermal system, resulting in low RTE. This research will provide scientific basis for heat transfer enhancement, system design and performance optimization of I-CAES.

Development of an acoustic flowmeter for low flow rates

The use of non-intrusive acoustic flow meters for residential applications has been little explored. This work presents the development of a non-intrusive acoustic instrument for low water flow rates measured at a PVC pipe knee. A chest piece of stethoscope with an electret microphone was used, and 10 collection cycles were performed, in a range of 16–488 L/h (lph). The results show that there is a quadratic relationship between the standard deviation of the acoustic signal and the water flow, and the existence of a transition region is predicted. Furthermore, there was an exponential relationship between the standard deviation of the detail coefficients of the Wavelet Transform and the energy of the approximation coefficients with the fluidic flow. Thus, as far as we know, this is the first time that a correlation between the acoustic noise generated by a low flow of water on a residential scale is presented. This approach represents a potential alternative for monitoring water consumption at specific points in a residence, which, in turn, enables the identification of user patterns and contributes to the management of the distribution of water resources in a given location.

Accumulation and removal of world's largest hydrocarbon resources with changing hydrology and climate in the Cenozoic

Hydrocarbon resources form from organic matter at moderate temperatures in sedimentary basins, under favorable conditions of migration and accumulation. This short communication examines how the global distribution of large hydrocarbon resources is influenced by long term solution and dissolution resulting from changes in climatic conditions. Laboratory experiments on water washing showed that water solubility of gas and light oil increases with temperature and decreases with salt content. Thus, water can transport hydrocarbons over large distances in the seaward direction, if stratigraphy and tectonic setting provide suitable aquifers, and if salinity is low. If salinity rises, for example due to high evaporation rates or contact with salt deposits or seawater, gas and light oil drop out of solution. This assumed water washing mechanism cannot act in areas with no or low water flow rates, such as arid or arctic regions, where hydrocarbons are not transported but remain in situ. Hydrocarbons accumulate under four major hydrological and climatic regimes.a) In deltas, or offshore areas next to outlets of great rivers.b) Offshore in humid and hot climate next to mountain ranges.c) Onshore in arid or semi-arid climate, and.d) Onshore in arctic regions.Climate changes in the Cenozoic severely affected the formation of hydrocarbon resources, due to alternations in temperature, precipitation and the hydrogeological cycle. The occurrence of permafrost is also relevant, as it prevents meteoric water from infiltrating and decomposing hydrocarbon accumulations by water washing at high latitudes. Recent natural phenomena show that present global warming threatens at least nine large hydrocarbon provinces in arctic regions already, as permafrost decomposes or ice sheets melt, becoming unable to act as seal for gas or light oil below any longer or as aquiclude, respectively.

Development and testing of a laboratory model of a two-turbine small hydroelectric power plant

This article considers the main methods of regulating water consumption and power of micro hydroelectric power plants. New technical solutions for screw jet turbines adapted to low pressures and water flow rates are proposed. The Archimede’s screw turbine is a cost-effective and environmentally friendly microhydropower technology that operates at high efficiency at low pressure and medium flow rates. In this case, the change in power depends on the following parameters: the number of blades, water flow, the angle of inclination of the blades and the height of the pressure. Preliminary calculations carried out by the authors show that the power of a microhydroelectric power station depends on individual factors of the area. With an increase in the speed of the water flow, the speed of the water wheel also increases, and in turn, the electric power of the microhydroelectric power station increases.

Dissolution of hydrogen produced by water electrolysis: Effects of electrode roughness factor and current density

In our basic study that used a low water flow rate of 100 ml/min, the amount of dissolved hydrogen produced during water electrolysis varied according to the roughness factor of the electrode, which is thought to affect the state of supersaturation at the electrode surface. However, at a high-water flow rate of 500 ml/min, which is commonly used in commercial and industrial contexts, no change in the amount of dissolved hydrogen was observed as a function of electrode roughness factor. We observed that, at water flow rates used in commercial and industrial applications, increasing the electrode area made it possible to decrease the supersaturation state and increase the hydrogen dissolution efficiency.

Effect of Installation Conditions of Water Mist Nozzle on Thermal Radiation Attenuation Performance

In this experimental study, the effect of installation conditions of a water mist nozzle on thermal radiation attenuation performance was investigated. Two types of nozzles (Small_nozzle and Large_nozzle) were used. Experiments were conducted under conditions in which the nozzle was installed near the heater and heat flux sensor (Position_NH and Position_NS, respectively), and water mist was discharged from one and two nozzles (Case_ID and Case_SD, respectively). To characterize the water mist spray, the water supply pressure and droplet size were measured, and visualization of the sprayed water mist was performed. The thermal radiation attenuation performance improved with an increase in the water flow rate, and Small_nozzle showed higher thermal radiation attenuation performance than Large_nozzle. Moreover, Case_SD showed lower thermal radiation attenuation performance than Case_ID_Sum (that is, the Sum of Case_ID & Position_NS and Case_ID & Position_NH) and the difference in thermal radiation attenuation performance between Case_SD and Case_ID_Sum at a higher water flow rate was more significant than that at a lower water flow rate. These might be attributed to the wide overlapping area of water mist discharged from two nozzles in Case_SD and at a higher water flow rate, narrowing the overall width of the water mist.

Experimental characterization of the coupling and heating performance of a CO2 water-to-water heat pump and a water storage tank for domestic hot water production system

This work presents an experimental study of the dynamic performance of a CO2 water-to-water heat pump in a domestic hot water production system. A facility was developed and used to characterize the time evolution of the COP of this heat pump, the heating and stratification processes of the hot-water storage tank, and the global COP of the system. Results showed that, when heating the water storage tank, strategies based on promoting stratification to reach Ri ∼40, such as the use of vertical tank filling velocities v ∼ 10-4 m·s−1 with low water flow rates between the tank and the heat pump gas cooler, permits an increase of ∼12.4% in the system global COP and a reduction of ∼16% of the compressor energy consumption compared to other strategies. However, strategies based on considering higher water flow rates (i.e. Ri ∼1) increase the thermal energy available in the tank (∼6% when flow rate and v increases a factor 3.6) but enhance the water mixing and extend the heating time which reduces the global COP of the system. Besides, an increase of the evaporator inlet water temperature from 5 °C to 20 °C increases the system global COP by 59% and reduces the heating time ∼40%.

Changing the guality of drinking water and the resistance of the pipeline when transporting it through water pipes

Transportation of drinking water on the water supply network is a complex and important problem, which requires many practical problems. Thus, the water supply network is designed for the regime of maximum water consumption in the settlement, and the period of operation of the network is characterized not only by maximum water consumption, but also by minimum water use, which takes place at night. Therefore, the velocities of water flow through the pipes will change during the day from maximum to minimum, and in some areas will fall to zero and even change the direction of flow. This situation contributes to the formation on the inner surface of water pipes of biological film, which develops on all types of pipe material (concrete, plastic, steel, cast iron, copper). Hours of minimal water consumption, characterized by low water flow rates, are favor able for the process of fixing bacteria on the inner surface of the pipes and the formation of local colonies that destroy the material of the pipeline.
 Special attention is paid to iron bacteria, which oxidize iron oxide, turning it into oxidative. This process is accompanied by precipitation,- hydroxide. Therefore, in the process of vital activity of iron bacteria in the middle of the pipelines formed a mobile sediment, which reduces the diameter of the pipes, and the water gets a rusty-red color and an unpleasant odor.
 Attention is drawn to the fact that some artesian waters used for water supply of the population contain hydrogen sulfide. When oxygen enters such bodies, they begin to develop filamentous sulfur bacteria. In appearance filamentous sulfur bacteria (Beggiaroacea) resemble long tufts of gray hair, and congestion, formed from filamentous sulfur bacteria rapidly increase in volume and clog the living section of the pipes, saturating the drinking water with an unpleasant odor.
 Therefore, bacteria transported through the pipes together with drinking water degrade its quality, saturating the water with an unpleasant odor, clog the living section of the pipes and destroy the inner surface of the pipes and destroy the inner surface of the pipes due to corrosion.

Improving mild steel corrosion resistance in tap water: Influence of water flow and supply rates

The mild steel corrosion has been studied in hot tap water (50 °C) using linear polarization technique in the laboratory set-up that models water circulating system. The influence of water flow rate (0.15–0.45 m/s) and water supply rate (0–70 % of system volume per hour) on corrosion kinetics have been investigated. The corrosion products, formed on the surface of the steel corrosion probes, have been analyzed with XRD. It has been found, that in condition of low water flow rate (0.15 m/s) and in the absence of water supply the corrosion rate is high (0.29 mm/year) due to low blocking abilities of the surface deposits. Amorphous Fe(OH)3 is the main corrosion product to be detected on the surface. The increase in water flow rate above 0.15 m/s and water supply rate above 30 % of system volume per hour leads to the 1.6 times corrosion rate reduction (to 0.18 mm/year) due to the formation of dense surface layer of calcium carbonate and iron oxyhydroxides. The results obtained can be utilized to improve the corrosion performance of hot water supply systems.

Experimental Study on the Characteristics of Sediment Transport and Sorting in Pressurized Pipes

Sediment transport in pipes is an effective engineering measure used to reallocate water–sediment resources and is widely used in reservoir flooding and sediment discharging, river dredging, floodplain area deposition, as well as other projects. An experimental investigation of sediment transport in pressurized pipes, with heterogeneous sediment (d50 = 107 μm) of the lower Yellow River as the experimental material, is presented. This study mainly explored the change law of sediment transport and sorting in pressure pipes with an internal diameter of 0.08 m. The experimental results reveal that the presence of sediment significantly changed the distribution of the flow velocity field. At the same flow rate, the velocity of the lower water body with a high sediment concentration decreased, while that of the upper water body increased. At a low water flow rate, the increase in sediment concentration caused an asymmetric distribution of the cross-sectional velocity. The vertical concentration decreased in height, and the obvious stratification of vertical sediment particles was observed. With the increase in the flow rate, the asymmetry of the velocity distribution significantly decreased, the concentration profile tended towards being uniformly distributed along the vertical direction, and the separation effect of the sediment particles weakened.

IMPROVING MILD STEEL CORROSION RESISTANCE IN TAP WATER: INFLUENCE OF WATER FLOW AND SUPPLY RATES

The mild steel corrosion has been studied in hot tap water (50 °C) using linear polarization technique in the laboratory set-up that models water circulating system. The influence of water flow rate (0.15-0.45 m/s) and water supply rate (0-70 % of system volume per hour) on corrosion kinetics have been investigated. The corrosion products, formed on the surface of the steel corrosion probes, have been analysed with X-Ray Diffraction (XRD). It has been found, that in condition of low water flow rate (0.15 m/s) and in the absence of water supply the corrosion rate is high (0.29 mm/year) due to low blocking abilities of the surface deposits. Amorphous Fe(OH)3 is the main corrosion product to be detected on the surface. The increase in water flow rate above 0.15 m/s and water supply rate above 30 % of system volume per hour leads to the 1.6 times corrosion rate reduction (to 0.18 mm/year) due to the formation of dense surface layer of calcium carbonate and iron oxyhydroxides. The results obtained can be utilized to improve the corrosion performance of hot water supply systems.

Heat and mass transfer of evaporative cooler with elliptic tube heat exchangers- an experimental study

In the present study, an evaporative cooling test system consisting of an elliptical-heat exchanger was examined. Tests were conducted for various airflow rates of 52, 68, 81, 96 Cubic Meter per Minute (CMM), sprinkler water flow rates of 30, 40, 50 Liter per Minute (LPM), and hot water flow rates of 18, 22, 28 LPM. The sprinkle nozzle types and outside wet-bulb temperatures were also investigated. The convective heat transfer of the sprinkle water film outside the tubes and the mass transfer between air and water film on tube bundles were probed. The film thickness and sprinkle water picture were studied using high-speed cameras and image processing techniques. The results show that the mass transfer performance of the evaporative cooler was enhanced with the growth of the airflow rate. When the sprinkler water flow rate rose to 50 LPM, the heat-mass transfer coefficient of the evaporative cooler decreased since the water film on the tube was thickened. The low hot water flow rate at the tube side (18 LPM) resulted in a superior performance due to a high local temperature and improved local mass transfer. The experimental data were used to obtain empirical correlations for the heat coefficient of the liquid film and mass transfer.

The synthetic effect of traditional-thermodynamic-factors (temperature, salinity, pressure) and fluid flow on natural gas hydrate recovery behaviors

The commercial exploitation of natural gas hydrates (NGHs) has been a growing research focus due to its features of enormous reserves and clean fuel. To guarantee the safe and efficient production of NGHs, we have proposed a novel strategy of water flow erosion to promote methane hydrate (MH) decomposition based on the tremendous seawater resource and the fundamental process of water-gas flow during NGHs exploitation. In this study, the synthetic effects of traditional-thermodynamic-factors (temperature, salinity, pressure) and fluid flow on MH decomposition characteristics, which is known little about yet, are comprehensively analyzed via in-situ magnetic resonance imaging (MRI). The temporal-spatial behaviors of MH decomposition are visually investigated. The results indicate that the pressure, salinity, temperature and water flow synergistically increased MH decomposition efficiency. Additionally, the propagation of the decomposition front along the interface between MH and ambient phase shows that the water flow rate and heat transfer are two crucial factors for accelerating MH decomposition. The higher water flow rate also efficiently complements the insufficient decomposition driving force due to the heat loss during MH decomposition process. The highest average decomposition rate (1.1%/min) and the relatively less water injection volume (320 mL) can be archived in this study. Furthermore, the decomposition rate has a significant dependence on temperature under lower water flow rate.

Heat Transfer Coefficient Estimation and Performance Evaluation of Shell and Tube Heat Exchanger Using Flue Gas

In the past few decades, water and air were commonly used as working fluid to evaluate shell and tube heat exchanger (STHE) performance. This study was undertaken to estimate heat transfer coefficients and evaluate performance in the pilot-scale twisted tube-based STHE using the flue gas from biomass co-combustion as working fluid. Theoretical calculation along with experimental results were used to calculate the specific heat of flue gas. A simplified model was then developed from the integration of two heat transfer methods to predict the overall heat transfer coefficient without tedious calculation of individual heat transfer coefficients and fouling factors. Performance including water and trailer temperature, heat load, effectiveness, and overall heat transfer coefficient were jointly investigated under variable operating conditions. Results indicated that the specific heat of flue gas from co-combustion ranging between 1.044 and 1.338 kJ/kg·K while specific heat was increased by increasing flue gas temperature and decreasing excess air ratio. The developed mathematical model was validated to have relatively small errors to predict the overall heat transfer coefficient. A flue gas mass flow rate of 61.3–98.8 kg/h, a water flow rate of 13.7–14.1 L/min, and a parallel arrangement of two water-to-air heaters in an empty trailer were found to be optimal conditions for space heating purpose. In addition, a lower poultry litter feeding rate decreased heat loss of flue gas and increased heat gain of water, while a lower water flow rate also provided a lower maximum possible heat transfer rate with a higher actual heat transfer rate to quickly achieve heat equilibrium that ultimately improves the performance. This study demonstrates the possibility of collecting residual heat from the flue gas using the pilot-scale STHE system while outlining a systematic approach and process for evaluating its performance.

Experimental thermal performance study of molten salt steam generator-superheater with saturated water

Molten salt steam generation is an important process in many high temperature thermal systems. In this paper, thermal performance of molten salt steam generator-superheater with saturated water was experimentally reported and analyzed. Experimental results showed that heat flow and thermal efficiency of evaporator were both significantly larger than those of superheater, and steam flow from evaporator influenced heat transfer of superheater, so evaporator dominated heat transfer performance of the whole system. In evaporator, boiling deterioration occurred with low water flow rate, while insufficient boiling appeared with high water flow rate, so inlet water flow rate should be increased properly to obtain suitable superheat and improve heat flow and thermal efficiency. Since heat losses of evaporator and superheater both increased with salt temperature/flow rate rising, their thermal efficiencies gradually dropped, while their effectiveness both increased with the increase of outlet temperature. Thermal resistance of superheater was about 6 times that of evaporator, and the thermal resistance of steam side in superheater accounted for more than 95% of its total thermal resistance. Therefore, heat transfer enhancement methods such as extended surface and spoiler technology should be adopted on steam side of superheater.

Mathematical description of water flow quantity for microhydroelectric station

The main methods of regulating water flow and power of a microhydroelectric power plant are considered. New technical solutions are proposed for screw jet hydraulic turbines adapted to low heads and water flow rates. Preliminary calculations carried out by the authors show that the power of a micro-hydroelectric power plant depends on the individual factors of the area.As the speed of the water flow increases, the speed of the water wheel also increases, and in turn, the electric power of the micro-hydroelectric power plant is increased.