Water-loop System Research Articles

Reduction of fines in recycled paper white water via cellulase enzymes

Due to the high wastepaper recyclability and water-loop system closure, packaging paper mills struggle with increased fines, causing runnability issues. Cellulase enzymes are a preferred treatment choice for the improvement of the pulp refining in stock preparation area but are not widely used or easy to introduce in the production process. Different cellulase enzymes were tested, and those with the highest activity were introduced to the white-water (WW) samples with the aim to reduce fines content as potentially new enzyme applications on the paper machine. The first portion of the study involved the development of an experiment model to find and confirm the optimal enzyme process parameters (40 °C, pH 5.7, reaction time 3 h, and 0.18% v/v enzyme addition) for laboratory made white-water. The second portion of the study included turbidity, colloidal charge, flow cytometry (FCM), and chemical oxygen demand (COD) analysis on industrial and laboratory made white-water samples at optimized process parameters. Obtained results corresponded to reduced fines content in white-water samples, which justified commercial usage of cellulase enzymes on recycled paper machine short loop and potentially increased machine runnability without negative influence on wastewater treatment plant.

Experimental investigation of an air source heat pump with multigroup heat pipe radiators

As a clean and sustainable electrified heating technology, air source heat pump (ASHP) has been widely used in household in China. However, some problems occurred with the commonly used water loop system, such as low efficiency, complicated structure, more likely to be frozen and burst as well as high electric energy consumption, etc. In this paper, a new air source heat pump with multigroup heat pipe radiators (ASHPMP) was presented. In ASHPMP system, the condenser and heat pipe were coupled together to form a new type of heat radiation terminal, which was named as heat pipe radiators, multiple terminals driven by the compressor provided heat for several rooms. An experimental apparatus of the ASHPMP system was developed and the experiment was carried out in residential buildings also, and R410A was used in the heat pump and R134a was used in heat pipes. The influence of temperature, pressure of heat pump and heat pipe on the heating performance of ASHPMP under frosting/defrosting condition was analysed. The results showed that the new system can operate stably under outdoor temperatures of −12.7 °C to 6.5 °C. As the indoor temperature was set at 20 °C, the heating coefficient of performance (heating COP) could reach up to 3.15 with outdoor temperature −12.7 °C, and it was 6.73 with outdoor temperature 6.5 °C.

CFD-FEA based model to predict leak-points in a 90-degree pipe elbow

The aim of this paper is to numerically investigate Vibration-Based Leak Detection (VBLD) method in pipeline systems based on Fluid–Structure Interaction (FSI) analysis to predict leakages. In previous investigations, laboratory tests were widely used to study the VBLD technique in small-diameter water loop system pipes. The current project uses Ansys Workbench to extend these findings by integrating Computational Fluid Dynamics (CFD) with Finite Element Analysis (FEA). The study outlines a numerical method for VBLD to identify leakages in a 90-degree pipe elbow by predicting variations in vibration signals, with applications in the oil and gas industry. Firstly, changes in fluid behaviour (centrifugal force, pressure drop, secondary flow, and frictional force) experienced in the internal pipe wall resulting from a probable leakage (modelled as an additional outlet) are determined using CFD. Subsequently, the CFD results are coupled with FEA to model structural responses of the pipe walls subjected to different forces. This in turn allows the variations in vibration signals to be measured. The numerical approach presented in this paper based on FSI and incorporating the VBLD method provides a practical and convenient early detection tool that can complement physical vibration monitoring equipment in the field.

Inversion Point of the Isothermal Reactivity Coefficient with Increasing System Temperature in a Heterogeneous Core Lattice of a Light Water Reactor

As part of efforts to develop coupled multiphysics experiments for the benchmark of modern multiphysics reactor simulators, a low-power and open-pool type of light water reactor at the Walthousen Reactor Critical Facility (RCF) was reconfigured with additional equipment, and its neutronic characteristics were fully surveyed. A water loop system was designed and installed to pass through the central region of the reactor core, making the central region overmoderated. The overmoderation would lead to a positive temperature reactivity feedback in the modified reactor configuration. This phenomenon is observed when the system temperature is between 10.69°C and 28.70°C. The inversion point of the isothermal reactivity coefficient is at 28.70°C ± 1.07°C. At this temperature, competition between the negative and positive thermal effects on reactivity compensate each other, and the isothermal reactivity coefficient becomes negative at temperatures higher than the inversion point. This paper presents the experimental determination of the isothermal reactivity and reactivity coefficient at different temperatures as well as the inversion point in the modified RCF reactor configuration. To obtain the best-quality results possible, special attention is given to the choice and adaptation of all the available methods for data postprocessing of experiment measurements. Neutron flux denoising is performed with multivariate wavelet transforms and principal component analysis. The Inverse Kinetics Method is applied to derive reactivity from the neutron flux measurements. To provide accurate and high-fidelity experiment benchmark data for modern code validation, in-depth experimental uncertainty quantification is developed. The results of the experiments show the mixed effects of system temperature on reactor reactivity due to the combined effects of Doppler broadening in the fuel, S(α,β) thermal scattering physics, and change in water density and can be used to validate previously developed cross-section interpolation models in the low-temperature range and positive isothermal reactivity coefficient conditions.

Closed Genome and Plasmid Sequences of Legionella pneumophila AW-13-4, Isolated from a Hot Water Loop System of a Large Occupational Building.

Unused water in unoccupied buildings can become stagnant, with reductions in temperature and levels of disinfectant resulting in increased microbial growth. We report the closed and complete genome and plasmid of Legionella pneumophila strain AW-13-4 (serogroup 1), which was isolated from a hot water loop system of a large building.

Controlling the Thermal Power of a Wall Heating Panel with Heat Pipes by Changing the Mass Flowrate and Temperature of Supplying Water—Experimental Investigations

Renewable energy sources for the purpose of heating buildings cooperate perfectly with so-called low-temperature heating systems. Water loop surface heating systems had been thoroughly tested. In contrast, thermal performance of wall panels with heat pipes have not been fully recognized, yet. The determination of the thermal power as well as the control of panels thermal performance cannot be performed with the methods developed for water loop systems. In this paper, the novel heating panels with heat pipes were tested to analyze the possibility of controlling their performance by changing the mass flowrate of heating water and its temperature. Specific heating power of the investigated panels varies from 16.9 W/m2 to 93.8 W/m2 when supplying a water temperature ranging from 35 °C to 65 °C and mass flowrate from 10 g/s to 47.5 g/s. Investigations revealed that the thermal performance of the panels is more sensitive to the changes of temperature than to the changes of mass flowrate of supplying water, and thus, should be controlled by changing the supply water temperature at low mass flowrates to obtain a low energy usage of pumps (diminished pressure losses) and good quality of controlling.

Development of critical experiments to provide validation data for multiphysics coupling codes

Modern reactor simulation tools provide advanced prediction capabilities by coupling multiphysics models to simulate reactor behaviors, involving thermal, neutronic, and mechanical interactions. To assure high-fidelity predictions by these tools, experimental data are needed to validate coupled-physics models deployed by these tools. In order to provide data to benchmark the feedback between thermal-hydraulic and neutronic simulations, coupled-physics critical experiments are designed and performed at a Reactor Critical Facility (RCF). The facility houses a low power and open-pool type light water reactor operated at the atmospheric pressure. The reactor allows flexible reconfigurations for many unique critical experiments. Recently, a water loop system has been designed and installed in the facility with the heated water circulating through the center of the reactor core, which broadens the range of validation experiments available for neutronics/thermal-hydraulics couplings. Direct effects of the loop water thermal dynamic change on reactor power and derived reactivity are demonstrated through a series of different experiments, including reactivity change over different loop water temperatures and reactor power evolution under influence of flow transient conditions in the water loop. Changes as low as 1% in the reactor power/neutron flux caused by small water temperature perturbations are observable experimentally.

Effect of the Air Flow Angle on a Microbubble Generator with a Spherical Body

This research has been carried out on the characteristics of a microbubble generator in a spherical body. It aims to study the influence of the air flow angle on generated bubble characteristics. A water loop system consisting of a water reservoir, an observation box, a pump, water and air flow meters, valves and a test section is used. The test section is a microbubble generator in the shape of a spherical body. Three types of microbubble generator with various air flow angles have been used as a test section at various water flowrates, air flowrates and height of water in reservoir. The tested parameter significantly influences the number and the size of the bubbles. Increasing the air flowrate increases the size of the bubbles, while increasing the water flowrate increases the number of microbubbles. The effect of the air flow angle in the microbubble generator is significant. A Microbubble generator with a 45° air flow angle produces a larger size of bubbles compared to a direct (0° air flow angle) microbubble generator. A microbubble generator with a 90° air flow angle could not suck up the air more than 0.1 lpm, so it is inefficient to produce bubble. From this study it is concluded that a microbubble generator is capable of producing microbubbles and the number and the size of bubbles is affected by the air flow angle.

The synthesis and characterization of a magnetite nanoparticle with potent antibacterial activity and low mammalian toxicity

Magnetite has shown some promise as a biomedical material and antibacterial agent; however the benefits are normally only realized when it is used in combination with other metals or drugs. Unfunctionalized magnetite may be a biocompatible alternative. This report discusses the synthesis and potent antibacterial activity, with low associated mammalian organ toxicity, of nanomagnetite particles. Magnetite (Fe3O4) nanoparticles were electrochemically prepared in a green surfactant-free, closed water loop system. These materials, characterized by X-ray diffraction, FTIR, and vibrational magnetometry, also appear contaminated with Fe-O-O-H functionalities. This physical characterization is accompanied by a computational investigation of truncated clusters showing that a magnetite-derived cluster of 7 iron atoms is a sufficient model to generate the vibrational frequencies experimentally observed in magnetite using DFT calculations. The nanoparticles, evaluated for antibiotic activity, were shown to have minimum inhibitory concentrations of 2.8 and 2.0 μg/mL against E. coli and S. aureus respectively. This is both a 100-fold lower concentration than the human cytotoxic dose determined by an MTT assay and is also comparable to the effective dose of traditional antibiotics. A dose-dependent decrease in catalase activity and an increase in the levels of lipid peroxidation suggests that these nanoparticles act through damaging the anti-oxidant systems in cells. However, renal and hepatic damage was only observed at daily doses (2 weeks) of 100 μg/mL and higher. This significant therapeutic window suggests that these materials might prove useful as potential complementary therapeutics in the future.

A Study on Type of Smart Water Grid Pipeline System (multi waterloop system) and Application Method

In these days, water-loop system using multi water resources is lively discussed. This system distributes water effectively by using multi water resources instead of new water resources development. Multi water resources consist of surface water, rainwater, reclaimed water, seawater etc. This system would be distributing sanitary water stably, and able to economical maintain the related facilities. Also, this system has an emergency reaction ability when system is faced with accident. Especially, if multi water loop system is constructed by using the city’s securable water, nation’s water resources will be utilized effectively and water resources will be developed or reused on a small scale. The neces elements of water-loop system design are suggested in this research. The elements are the followings; Model of connected water-loop pipe networks, platform model of multi water resources loop system, range of technology, difference with existing systems and direction of construction.

CORROSION BEHAVIOR OF NUCLEAR GRADE ALLOYS 690 AND 800 IN SIMULATED HIGH TEMPERATURE AND HIGH PRESSURE PRIMARY WATER OF PRESSURIZED WATER REACTOR

The corrosion behaviors of nuclear grade commercial alloys 690 and 800 were studied by in situ electrochemical measurements using a self-built high temperature and high pressure water loop system,combining with SEM observation and XPS analysis.The results show that the corrosion potentials of alloys 690 and 800 decrease gradually with immersion time increasing,while the immersion time has no obvious impact on the result from electrochemical impedance spectroscopy(EIS).A large number of needle-like oxides have been found on the surface of alloy 690 after being exposed to high temperature and high pressure water for 408 h.For alloy 800,except needle-like oxides,many particle oxides are also observed.For alloy 690,Cr is rich at inner side of oxide film,while it is rich at outer side of oxide film for alloy 800.Alloy 690 shows better corrosion resistance than alloy 800 in high temperature and high pressure water.After immersion experiment,the contents of Ni~(2+),Cr~(3+) and Fe~(3+) ions in the test water solutions are 0.1×10~(-6),0.1×10~(-6) and 0.3×10~(-6),respectively.

DEVELOPMENT OF THE HIGH TEMPERATURE FRETTING WEAR SIMULATOR FOR STEAM GENERATOR

In nuclear power plant, fretting wear due to a combination of impact and sliding motions of the U-tubes against the supports and/or foreign objects caused by flow induced vibration, can make a serious problem in steam generator. A test rig, fretting wear simulator, is developed to elucidate fretting wear mechanism qualitatively and quantitatively. The realistic condition of steam generator of high temperature up to 320°C, high pressure up to 15 MPa, and water environment could be achieved by a test rig. The fretting wear simulator consists of main frame, water loop system, and control unit. Actual contact region under a realistic condition of steam generator was isolated using autoclave. Effects of various parameters such as the amounts of impact and sliding motions, applied loads and initial gaps and so forth are considered in this research. After the experiment, wear damage was measured by a three-dimensional profiler and the surface was also studied by SEM microscopically. Initial results were also presented.

Continuous Commissioning® of a Commercial Building in Austin, Texas

ABSTRACT Continuous Commissioning®* technology has been proven to be highly cost-effective in reducing building energy consumption. This article illustrates a successful continuous commissioning project that has been recently completed in a commercial building in Austin, Texas. Even though the building's HVAC systems were well maintained and their operations had been tuned by an experienced facility management team, the CC® project was still able to achieve an annual cost saving of $287,400 (14 percent of the total utility costs, or 60¢ per square foot per year) by further optimizing the operations of various HVAC components, the chilled water and hot water loop systems, and identifying malfunctioning control devices. The simple payback of the CC project was estimated to be less than 7 months.

An in Situ Raman Spectroscopy System for Long-term Corrosion Experiments in High Temperature Water up to 673 K

A Raman spectroscopy system has been developed, in order to identify metal oxides formed on the surfaces of metals and steels in high temperature water up to 673 K. A supercritical water loop system including a Raman cell was installed. The design of the loop system is up to 673 K and 40 MPa. The Raman cell has a diamond window without window-to-metal packing. Raman spectrum of alumina plate was measured at room temperature, at 523 K and at 673 K under pressure of 25 MPa. A long-term measurement was also performed at 523 K and 25 MPa for 117.5 h. In all cases intense Raman peaks attributed to alumina were observed. Raman spectrum of anatase particles in suspension was measured at 673 K and 25 MPa. The results show that the Raman spectroscopy system developed in the present study works well not only for plate sample but also for suspension. Raman spectra observed for titanium plate in high temperature water of 673 K and 25 MPa show growth of several Raman peaks with time up to 257 h. The peaks disappeared after cooled down to room temperature. The experimental results have demonstrated importance of in situ Raman spectroscopy.

Corrosion behavior of Zr alloys with a high Nb content

The corrosion behavior of the Zr alloy with a high Nb content was evaluated in the water loop system containing 2.2wppm Li and 650wppm B. The characteristics of the precipitates were analyzed by transmission electron microscopy (TEM) and the oxide was characterized by an X-ray diffraction method using a synchrotron radiation source. On the basis of the results obtained by these measurements, the relationship among the oxidation behavior, the precipitate characteristics and the oxide properties was discussed. It was shown that the Cu addition was of benefit to the corrosion resistance of the Zr alloy with a high Nb content and the corrosion resistance of the Cu-containing alloy (Zr–1.5Nb–0.5Sn–0.2Fe–0.1Cu) was superior to that of the Cr-containing alloy (Zr–1.5Nb–0.5Sn–0.2Fe–0.1Cr). The fine β-Nb precipitates were found more frequently in the Cu-containing alloy than the Cr-containing alloy when heat-treated in the same condition. The fraction of the tetragonal zirconia in the region of the metal/oxide interface was higher in the Cu-containing alloy than the Cr-containing alloy, suggesting that the stabilization of the tetragonal phase in the oxide was promoted more when the smaller precipitates are incorporated into the oxide. It is concluded that the fine distribution of β-Nb is desirable for stabilizing the tetragonal phase in the oxide, thereby increasing the corrosion resistance of the Zr alloy with a high Nb content.

An ambient water loop system for USP purified water

An ambient loop USP purified water system has been designed and implemented using carbon and ion exchange resin beds, ultraviolet light systems and polishing filters to produce water consistently meeting or exceeding all USP XXIII quality specifications for purified water. The circulation system is constructed of PVDF plastic piping material installed in a continuous fully-drainable loop. The system was sized for a pilot scale fermentation/harvest process at the 1000 l cultivation scale. This system passed all installation and operational qualification testing as well as sixty days of continuous performance qualification testing before entering into an ongoing monitoring regimen. Excursions outside acceptable water quality parameters during this extensive monitoring regimen were minimal. Sanitization of the system, along with bed and filter changes at the time of sanitization, was conducted every 3 to 6 months to insure consistent water quality.

Start-stop control strategies for heat recovery in multi-zone water-loop heat pump systems

A study is made to determine the energy saving potential of a start—stop controlled water-loop heat pump (WLHP) system. The physical model consists of individual heat pumps for each zone, a two-pipe water-loop system (with and without a storage tank), a boiler and an evaporative cooler. The overall system consists of four input energy controllers and an equal number of mass flow rate controllers. A simple start-stop control strategy for the system is developed. Results showing the typical daily operation of the system under changing heating and cooling loads are presented. A method for selecting the appropriate limits for loop water temperature which results in energy savings is given.

Radiochemical analysis of corrosion product mixtures from high temperature pressurized water loop systems

Radiochemical analysis of corrosion product mixtures from high temperature pressurized water loop systems

Radiochemical analysis of corrosion product mixtures from high temperature pressurized water loop systems

This paper describes the various types of samples of activated corrosion products obtained from the high-temperature pressurized water-loop facilities in the NRX reactor and the radiochemical procedures and radioactivity assay methods which are used in analysis of these samples.Typically, in-pile loops are simulated reactor systems, i.e. they consist of a primary flowing coolant system and auxiliary make-up, purification, sampling and cooling systems. Two of the loops in NRX, namely, the carbon steel English Electric Corporation “Leo” loop and the Bettis Atomic Power Laboratory central thimble CR-V Loop, are described with particular attention to their associated sampling facilities: autoclaves and out-pile test sections for corrosion and corrosion product deposition studies, hot and cold corrosion product filters for filtration of insoluble materials, and ion exchange columns for purification of the loop water and the study of the ion-exchange behaviour of activated water-borne corrosion and fission products.The types of samples obtained and the method of attack used to separate and isolate specific fractions of the mixed corrosion products are described. In particular, the separation scheme devised is one which permits the isolation of elements of the first transition series and their associated activated impurities from one another. The separation is basically an anion exchange technique involving the successive elution of carrier-equilibrated species.Resin samples from the loop purification system are attacked in the presence of carriers by either digestion with H2SO4-HNO3 or by alkaline fusion.In some cases, corrosion product deposits are assayed directly for activity distribution by means of gamma-scintillation spectrometry (differential pulse height analysis). Application of composite gamma-ray spectrum resolution to deposition coupons and pipe samples is described.The radionuclides found in loop water and in unfilterable corrosion products are mainly radiative neutron capture products of the corroded in-pile and out-pile materials. The main nuclides analyzed for are 45.1 d Fe59, 5.25 y Co60, 27.8 d Cr51, 12.8 h Cu64, 2.58 h Mn68, 2.56 h Ni65, 245 d Zn65 and 65 d Zr95. Fast neutron reactions have been also observed through the appearance of 300 d Mn54 and 72 d Co58. Two radionuclides observed in the water and in solid corrosion products are 60 d Sb124 and 2.8 d Sb122. The source of these radionuclides has not been positively identified. The corrosion products from the CR-V loop also contain 253 d Ag110m, 43 d Cd114m and 50 d In114m arising from the corrosion of an in-pile specimen of a Ag-In-Cd alloy.Radioactivity assay of the purified fractions from separated samples is mainly by γ-ray scintillation spectrometry. Routine activity assay utilizing comparison with standardized differential pulse height distributions for pure radionuclides has been adopted because of the versatility of its use for both separated and gross samples. Conventional end-window beta-proportional counting techniques are used for those nuclides whose decay modes and energies preclude gamma-ray intensity assay techniques.The complexity of corrosion product mixtures from in-pile loops requires that stringent control be maintained at all phases of the program from the time of sampling to the time radioactivity assay is completed. Several problem areas are discussed. For example, large amounts of Fe59 contaminating Co60 samples and Zr95 contamination of Mn54, are difficult to detect without considerable scrutiny of counting data. Carrier exchange is difficult to effect in some cases: e.g. Zr96-ZrN exchange. The gamma-counting data in particular receive careful scrutiny. The gravimetric assay of carrier yield is in some cases a doubtful and time-consuming operation ; therefore, techniques eliminating gravimetric procedures should be explored.

Visual Observations on the Water Stream In An Elevated Temperature High Velocity Loop

The role of oxygen in the corrosion associated with high temperature water systems utilizing low carbon steel containment has been under study for many years. This report describes the “in situ” visual effects of oxygen and oxide coatings on the corrosion occurring in a high velocity water loop system at temperatures up to 600 F. The visual effects are correlated with previously reported corrosion data measured by physical methods. It is concluded that oxygen inhibits the corrosion process. 3.4.6