Liquid Leakage Research Articles

A Study on the Actual Application of Superconducting Cables to the Network

Superconducting cables can transmit large electricity with compact size. They are expected to be installed in crowded underground at larger city. Actually, some superconducting cables are being operated in the world. In order to apply this superconducting cable to network, it is necessary not only to pass the commissioning tests, but also to ensure long-term reliability and to ensure safety in the event of a possible accident. The authors have conducted actual system operation of superconducting cables in Yokohama and have grasped their long-term characteristics. In addition, we have been conducting research on analysis when a short-circuit current flows through a superconducting cable and phenomena when a ground fault occurs. When a short-circuit current flows, it is important how to suppress the temperature rise. For that purpose, it is effective to connect copper wires in parallel with the superconducting conductors. It has been pointed out that the thermal insulation pipes may be destroyed in a ground fault, and it is necessary to take measures when liquid nitrogen leaks to the outside of the cable. This paper reports the items to be considered when applying superconducting cables to the network and the measures in the event of an accident.

Flash-Boiling Characterization During Ingress of Coolant Event for Dust Issue in ITER

Abstract Dust resuspension inside the vacuum vessel (VV) is one of the safety issues of the fusion reactor ITER. Plasma interaction with the plasma facing components (PFC) leads to their erosion, generating dust. One of the accident scenarios leading to dust resuspension is the ingress of coolant event (ICE) where a leak of the coolant pipes inside the VV conducts to injection and flash atomization of the cooling water. The metallic dust, produced by the erosion, is then oxidized by water throughout an exothermic reaction that produces hydrogen leading to a loss of confinement risk due to hydrogen and dust combustion. The steam flow, produced by the flash atomization of the liquid leaking from the breach, is considered to be the main source of dust resuspension. Therefore, experimentations about the two-phase flow generated by the flashing liquid jet are important to identify the main physical phenomena involved in the aerosol particles resuspension for ITER-like conditions that impose in particular low pressure level. Flash-boiling experiments were conducted under primary vacuum conditions. We studied the behavior and the structure of the flow resulting from superheated water injection into low pressure environment. Using shadowgraphy and particle image velocity (PIV), qualitative information and quantitative measurements on the two-phase flow that develops for different superheat conditions were gathered. The measured spray lateral spreading and droplets velocity are shown to increase with the superheat level. The use of a transparent nozzle also confirmed the strong coupling between the external structure of the atomized spray and the two-phase flow that develops upstream of the coolant circuit breach.

Construction of highly efficient heat conduction channels within expanded graphite/paraffin phase change composites and their thermophysical properties

Paraffin waxes (PW) are organic phase change materials (PCMs) that can be potentially applied for the storage/release of low-temperature latent heat and thermal management. However, they have serious liquid leakage and poor thermal conductivity, which greatly restrict their practical application. Although numerous studies have been conducted to address these problems, it is challenging to achieve phase change composites (PCCs) that are characterized by high thermal conductivity and excellent phase change behavior. Herein, we put forward a novel strategy for preparing expanded graphite (EG)/PW binary PCCs with EG loading varying in the range of 10–40 wt%. The method is developed by constructing graphite sheets with high orientation inside the PCCs following compression induction. The highly oriented graphite sheets provide channels for highly efficient heat transfer, which significantly improves the thermal conductivity of the resulting EG/PW PCCs. The in-plane thermal conductivities of the EG/PW PCCs are in the range of 10.7–49.7 W m−1 K−1 under 10–40 wt% EG loading conditions, much larger than those of the previously reported EG/PW PCCs with the same EG content. The EG/PW composites also exhibit excellent compatibility, uniformity, thermostability, reliability, and phase change behaviors. These remarkable properties make the EG/PW composites promising for application in thermal management and heat storage. This work provides an efficient and generic strategy for designing and constructing high-efficiency heat transfer channels within the PCCs using sheet-shaped fillers with high thermal conductivity.

Three-Dimensional Printable, Highly Conductive Ionic Elastomers for High-Sensitivity Iontronics.

The development of hydrogels and ionic gels for applications in fields such as soft electronics and wearable sensors is limited by liquid evaporation or leakage. Ionic conductors without volatile liquids are better choices for flexible and transparent devices. Here, a liquid polymer electrolyte (LPE) is prepared from a mixture of lithium bis(trifluoromethane)sulfonimide and polyethylene glycol (PEG) above the melting point of PEG. A three-dimensional (3D) printable solvent-free ionic elastomer (IE) is introduced by photopolymerization of ethyl acrylate and hydroxyethyl acrylate in the prepared LPE. The conductivity is significantly improved by the presence of a high content of the lithium salt. Dynamic cross-linking networks improve the stretchability and resilience of the elastomer. The pattern design capability of the IE is provided by light-curing 3D printing. These features demonstrate that the IE has broad application prospects in flexible sensors, ion skins, and soft robots.

Research on Soil and Nutrient Losses through Liquid Runoff, in Order to Mitigate the Climate Risks to Which Romania Is Exposed, in the Context of CAP

The current paper presents the monitoring of soil and nutrient losses through runoff as the result of the climate change. The experimental results were recorded on the standard plots for runoff and erosion control. The results of the studies carried out highlight that total nitrogen losses range from 0.05 kg/ha to 12.60 kg/ha, potassium displaced from the plots has values between 0.02 and 1.35 kg/ha, the humus associated with the eroded soil includes values between 0.51 and 176.5 kg/ha, phosphorus is recorded with maximum values of 0.39 kg/ha, the total iron losses have values between 3.14 and 431.16 g/ha, manganese has losses from 1.69 to 290.82 g/ha, copper losses range from 0.15 to 7.62 g/ha, and, regarding zinc, the values are within the limits of 0.25–57.22 g/ha. The maximum values of the displacement of fertilizing elements from the sloping agricultural lands, by means of liquid and solid leaks, are registered at the plots left as permanent black fields, the plots practically unprotected against the rain erosion. The experiments were performed at the Soil Erosion Research and Development Station “Mircea Moțoc”, Perieni/Staţiunea de Cercetare Dezvoltare pentru Combaterea Eroziunii Solului “Mircea Moţoc”, Perieni (SCDCES—MM, Perieni), Vaslui County, an institution strategically located in an area subject to erosion soil. Additionally, the paper envisages how the National Rural Development Programme (NRDP) and the Common Agricultural Policy (CAP) can be of use in this area by analysing past lessons and providing an overview of what was done.

Polyimide/boron nitride composite aerogel fiber-based phase-changeable textile for intelligent personal thermoregulation

Aerogel fibers, which are beneficial for enhancing the thermal response and preventing the leakage of phase-changeable materials (PCMs) during phase change process, are excellent candidates for phase-changeable textiles with excellent thermoregulating performance. Herein, polyimide/boron nitride (PI-BN) composite aerogel fibers with highly porous structure and good mechanical strength have been prepared by freeze-spinning technique, which could be served as the heat conduction path and skeleton for PCMs. Into the pores of the PI-BN aerogel textile was incorporated polyethylene glycol (PEG) by vacuum impregnation to obtain phase-changeable PI-BN/PEG textile. The high thermal conductivity of PI-BN skeleton could endow the quick thermal response rate of PI-BN/PEG textile upon the phase change process, while the high porosity of aerogel fiber could allow high loading of PEG and inhibit liquid leakage during phase change process. The resultant PI-BN/PEG composite textile has high thermal conductivity (5.34 W m−1 K−1), high enthalpy (125.2 J g−1) and excellent work stability after 100 heating-cooling cycles, accounting for the desired thermoregulating performance. Moreover, polydimethylsiloxane (PDMS) has been coated on the surface of PI-BN/PEG textile, endowing the textile hydrophobicity, waterproofness and washability, indicating its great potential as candidate for personal thermal management.

Preparation and characterization of polyethylene glycol‐based form‐stable phase change materials supported by poly (vinyl formal) foams

AbstractPhase change materials (PCMs) are a kind of materials that provide latent heat at a constant temperature. They have great potential in thermoregulation scopes and thermal energy storage. However, liquid leakage during phase transition restricts their applications in practice severely. In this work, a novel strategy is proposed to prepare form‐stable phase change materials with polyvinyl formal (PVF) foam shape‐stabilized poly (ethylene glycol)‐based material. The PEG exhibits good interfacial compatibility with the PVF framework and the phase transition enthalpy ranges from 104.1 to 158.4 J/g. The PEG/PVF‐C2 increases the residue amount from 0.1% to 4.2% and enhances the thermal degradation temperature at the same time. The mass retention rates of PEG/PVF composites depend on their pore structure, which are 75.4%, 89.5%, and 95.3%, respectively. This study may open a new door for the development of advanced PCMs with good leakage prevention and flame retardancy, thus further contributing to extending the application scopes.

Аналіз характеристик кумулянтної системи виявлення витоків рідини у трубопроводах

Acoustic noise signals that are generated by fluid leakage due to a leak in the pipeline have in general case non-Gaussian distribution, so for the further development of acoustic contact leak detection together with correlation-spectral methods it is advisable to use methods used for probabilistic analysis of non-Gaussian processes, in particular cumulant methods of noise diagnostics. The principle of cumulant method of liquid leakage detection in pipelines during operation is considered, which is based on the use of cumulants to distinguish acoustic noise signals registered at the control points of the pipeline section, namely on use of the distance between the cumulant vectors of signals and the mutual correlation function of signals. The block diagram of the cumulant system for liquid leakage detection is given. In order to use the cumulant leakage detection system for power plant diagnosis, a layout of the acoustic leak detection system has been developed, which is a hardware-software complex that performs the collection, registration and statistical processing of acoustic noise signals, as a result of which a decision is made on the presence or absence of leakage, the parameters of the hardware part of the system were given. To obtain estimates of the statistical characteristics of real leakage signals, an installation was used that allows to perform physical modeling of fluid leakage in a pipeline in standing water under sustainable conditions, with fixed leak dimensions and pressure level control. Acoustic noise generated by the flow of fluid moving in the heat pipeline is used as interference. Using the statistical characteristics of real signals, the characteristics of the cumulant leakage detection system were determined – leakage signal attenuation; the maximum distance between the transducers at which the leakage is detected; detector sensitivity; the influence of bandpass filtering on these characteristics is investigated. Keywords: acoustic contact leak detection, liquid leakage detector, acoustic noise signals, cumulant analysis

Study on energy storage performance of thermally enhanced composite phase change material of calcium nitrate tetrahydrate

In this study, a layer of nano-alumina film was coated on the EG surface and the matrix material was then mixed with molten calcium nitrate tetrahydrate salt to form a CPCM (MEG-CN4W). The prepared materials were characterized by Fourier transform infrared spectroscopy, X-ray diffractometer, contact angle measurement, thermal conductivity measurement and other techniques. When MEG has a mass ratio of 8% ~ 10%, the average phase transition enthalpy value of MEG-CN4W is 123 J/g, the phase transition temperature is 42.7 °C, and the peak temperature is 49.7 °C. The average activation energy of this CPCM is lower than that of CN4W. The thermal conductivity is 13 times higher than CN4W. On this basis, the cyclic thermal stability analysis of CPCM was carried out. MEG-CN4W was found to be stably and highly adsorbed on the expanded graphite surface after 200 heat storage-release cycles without liquid leakage. The phase change temperature and enthalpy value remained nearly unchanged, indicating that the prepared CPCM has potential application prospects.

A Repeatable Self-Adhesive Liquid-Free Double-Network Ionic Conductor with Tunable Multifunctionality

Liquid-free ionic conductors (LFICs) have promising applications in flexible electronics because most ionic conductors currently suffer from ionic liquid leakage or water evaporation issues. However, it has been a formidable challenge for LFICs to achieve long-term repeated self-adhesion on different substrates, especially on soft biological tissues. Based on the double-network design concept, we first fabricate a series of repeatable self-adhesive liquid-free double-network ionic conductors (SALFDNICs), consisting of stretchable first poly(AA-ChCl)-type supramolecular deep eutectic polymer networks and stiff second polydopamine (PDA) networks, which can maintain sufficient dynamic hydrogen bonds and catechol groups in the ionic conductors by preventing the overoxidation of dopamine, thus balancing the contradiction between adhesion and cohesion in liquid-free ionic conductors. Therefore, SALFDNICs can instantly form various interface interaction forces with multiple substrates (adhesion strength up to 757 N/m) and firmly adhere to various substrates for 20 detachment-reattachment cycles with a reduction in adhesion strength of less than 15%. Furthermore, SALFDNICs also have other comprehensive properties, such as optimum self-healing properties (self-healing efficiency of 90%), good stretchability (strain at break of 1200%), and promising conductivity (2.31 × 10-2 S m-1). Therefore, we believe that the extraordinary performance of SALFDNICs is important for improving device integration and the further development of flexible electronics.

Soft elastomer coatings for ionogels

Ionogels are stretchable ionic conductors with unique advantages, such as non-volatility, thermal, chemical, and electrochemical stability. Nevertheless, the exchange of solvent between ionogels and the external environment hinders their applications. Ionogel has the problem of ionic liquid (IL) leakage, or the ionogel absorbs moisture from the atmosphere. Here we develop a strategy to coat thin elastomers on ionogels. Silanes are added into the precursor of ionogels and elastomers to form a strong interface adhesion between the two polymer networks. The elastomer coating can prevent ionogels from absorbing moisture or leaking ionic liquid, while does not change their transparency, stretchability, and conductivity. We establish a procedure to quantify the loss of ionic liquid from ionogels, with the calibrated relation of conductivity/volume ratio. We find that the elastomer coatings work well because of their low diffusivity to ionic liquid on the order of 10−16m2/s. The coating strategy would be universal to various ionogels and elastomers, thus we expect its application in soft robots and stretchable devices made of ionogels.

Failure analysis of leaks due to cracks in hydrogen transfer lines of ESS cryogenic moderator

The ESS cryogenic Moderator System (CMS) has been designed to slow down the high-energy neutrons by means of two hydrogen moderators (to be increased to four in the future) by using forced flow of subcooled liquid hydrogen with a temperature of 17 K at 1.0 MPa. A liquid hydrogen leak is considered the most severe failure for the CMS. A leak scenario from the transfer line to its vacuum envelope through a crack have been analyzed and the expected results will be presented in this paper. An analysis code has been developed and calculated the pressure and temperature changes in the CMS process line and its vacuum envelope. The effect of the crack sizes is clarified. The consequential temperature changes along the vacuum envelope as well as the pressure drops were calculated. The required size of the safety relief device in the hydrogen transfer line and its vacuum envelope have thereby been determined and implemented.

Comparison of pyrite-phase transition metal sulfides for capturing leaked high concentrations of gaseous elemental mercury in indoor air: Mechanism and adsorption/desorption kinetics

Understanding the characteristics of pyrite-phase transition metal sulfides for the adsorption and desorption of gaseous elemental mercury (Hg0) is of vital significance for their applications in gaseous Hg0 capture. In this study, the adsorption and desorption of gaseous Hg0 onto pyrite-phase transition metal sulfides (i.e., FeS2/TiO2, CoS2/TiO2, and NiS2/TiO2) were compared, and the mechanisms of their differences were revealed by the kinetic analysis. The Co/NiS and SS bonds in dumbbell-shaped CoS2 and NiS2 were not entirely broken after oxidizing physically adsorbed Hg0, whereas the FeS and SS bonds in dumbbell-shaped FeS2 were. Thus, the activation energies of CoS2/TiO2 and NiS2/TiO2 for oxidizing physically adsorbed Hg0 were smaller than that of FeS2/TiO2, causing the stronger abilities of CoS2/TiO2 and NiS2/TiO2 to oxidize physically adsorbed Hg0 than that of FeS2/TiO2. However, the bonding strengths of Hg-S in HgS adsorbed on dumbbell-shaped CoS2 and NiS2 were relatively weaker because of the sharing of S2− in HgS with S− and Co2+/Ni2+, causing the decreases in heat stabilities of HgS adsorbed on CoS2/TiO2 and NiS2/TiO2. Therefore, HgS adsorbed on CoS2/TiO2 and NiS2/TiO2 can be voluntarily decomposed to release gaseous Hg0, which should be combined with FeS2/TiO2 for the emergency treatment of liquid Hg0 leakage indoors.

Calculation of the Height of the Water-Conducting Fracture Zone Based on the Analysis of Critical Fracturing of Overlying Strata

Accurate division of the water-conducting fracturing zone (WCFZ) in the mining overburden serves as an important basis to evaluate the stability of coal mining under water bodies. Research on the WCFZ is conducive to controlling surface subsidence and realizing safe coal mining under water. Traditionally, the WCFZ is generally determined by field observation (liquid leakage method, borehole television, etc.) or empirical formula. Although these methods boast high accuracy, they are time-consuming and laborious and have some problems such as weak pertinence and a large value range. In this study, a mechanical model under the critical breakage condition of hard and soft strata was established on the basis of the specific geological and mining information of a mine. Besides, the stability condition for the broken strata to form the “masonry beam” structure and the deflection-based bending deformation formula of hard and soft strata were deduced, and the method of calculating the height of WCFZ based on the analysis of critical fracturing of soft and hard strata (hereafter referred to as the CFSHS-based height calculation method) was proposed. Furthermore, with reference to the results of specific engineering tests, the height of the WCFZ in the working face 15,101 of coal mine XJ was analyzed by means of theoretical analysis, numerical simulation and engineering verification, which verifies the rationality and practicability of the CFSHS-based height calculation method.

Coulometric back titration based on all-solid-state electrodes for phenylephrine hydrochloride determination.

Existing coulometric titration generally used liquid reference electrodes, with limitations of frequent maintenance and liquid leakage risk and requiring vertical working position. Herein, we proposed an all-solid coulometric titration based on the glassy carbon electrode (GCE) and preliminarily utilized it in phenylephrine hydrochloride (PHE) analysis with a universal back titration program. Subsequently, the long-term stability of the GCE in bromine and iodine solution was evaluated comprehensively by electrochemical characterization and titration measurement. The results presented an excellent linear relationship between electrolysis time and PHE concentration from 0.3 to 20mM, with a limit of detection of 0.07mM (3 S0/S). It also showed an excellent standard recovery rate and a short testing time within 10min. Compared with bromometry in the pharmacopoeia, the all-solid coulometric titration exhibited higher accuracy and precision in formulation detection with simpler operation. The long-term stability experiments indicated that the potential difference mutation was unaffected by the electrochemical property of the GCE. Conclusively, this enabling work provided an all-solid coulometric titration for drug determination without maintenance in the long term and contributed to its further integration and industrialization.

Stearic acid/expanded graphite composite phase change material with high thermal conductivity for thermal energy storage

In this study, expanded graphite (EG) was added to melted stearic acid (SA) by the melt blending method to prepare SA/EG composite phase change material (PCM) with different ratios. EG with ultra-high porosity and large specific surface area can effectively adsorb melted SA through capillary force and van der Waals force. The results showed that when the loading amount of EG was 12 wt.%, almost no liquid leakage occurred and the composite showed excellent stability. In addition, the three-dimensional network structure of EG interconnection provides an efficient heat transfer path and reduces the thermal resistance of the interface. Therefore, the thermal conductivity of the composite was as high as 6.54 W m−1 K−1, which was 19.179 times higher than that of pure SA. Furthermore, the melting enthalpy and melting temperature of the composite were 163.35 J g−1 and 67.08 °C, respectively. X-ray diffraction and Fourier transform infrared spectroscopy shown that physical interaction instead of chemical reaction happened between EG and SA. When the mass fraction of EG is 12 wt.%, the composite PCM shows a relatively more balanced and uniform thermal image compared with SA, and the heat storage rate of the composite PCM was about 2.3 times of SA, and the heat release rate was 3.1 times of SA. In addition, the composite PCM showed excellent thermal stability, chemical stability, and cyclic stability, indicating that the working performance of the composite PCM was relatively stable within the temperature range of 100 °C.

A high efficiency fluidly reconfigurable antenna with detached feeding

AbstractIn this study, a pure water antenna with a tunable radiation pattern is proposed, which combines the idea of the Yagi antenna and the reflector antenna to realize a steerable directional beam. By sufficiently utilizing the excellent features of water: fluidity, transparency, and reconfigurability, this proposed design achieves a 360° beam coverage. In addition, a detached feeding structure is introduced to effectively avoid liquid leakage and corrosion. This type of antenna has 25 different working states covering the working frequency from 2.36 to 2.6 GHz (S11 < −10 dB), a high radiation efficiency (70%), and a maximum realized gain of 5.8 dB. This design is expected to be a promising candidate for the internet of things applications.

Phase Change Material with Gelation Imparting Shape Stability.

Blending two gelators with different chemistries (12-hydroxystearic acid and a bis-urea derivative, Millithix MT-800) was used to impart shape stability to CrodaTherm 29, a bio-based phase change material (PCM), melting/crystallizing at near-ambient temperature. The gelators immobilized the PCM by forming an interpenetrating fibrillar network. 15 wt % concentration of the gelators was found to be effective in preventing liquid PCM leakage. In order to improve the mechanical properties and thermal conductivity (TC) of the PCM, gelation of suspensions of multiwalled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GnPs) in a molten material was done at concentrations exceeding their percolation thresholds. Compared to pristine PCM, the gelled PCM containing 3.0 wt % of GnPs demonstrated a shorter crystallization time, ∼1.5-fold increase in strength, improved stability, and ∼65% increase in TC. At the same time, PCM filled with up to 0.6 wt % of MWCNTs had diminished strength and increased leakage with a slight TC improvement. Gelation of PCM did not significantly alter its thermal behavior, but it did change its crystalline morphology. The developed shape-stable PCMs may have a wide range of applications in ambient temperature solar-thermal installations, for example, temperature-controlled greenhouses, net zero-energy buildings, and water heaters.

Proposed Standards and Methods for Leak Testing Lithium-Ion Battery Packs Using Glycol-Based Coolant with Empirically Derived Rejection Limits

<div class="section abstract"><div class="htmlview paragraph">Lithium-ion battery systems are an energy source for a variety of electric-vehicle applications due to their high energy density and low discharge rates. Battery packs, whether made of prismatic, cylindrical or pouch cells, are cooled by common automotive thermal management systems. The rapid detection of battery pack coolant-system leaks during production operations is essential for meeting necessary safety and service-life requirements. Industry standards for measuring leak rates for both glycol-based and refrigerant-based cooling systems, however, currently do not exist. This presentation will discuss how leaks in water-glycol cooling circuits can be detected reliably and quantitatively through detection of escaping test gas as an indicator of ethylene glycol leaks and how the test gas leak rates correlate to the liquid leakage of the cooling liquid. Influencing variables such as leakage channel diameter, pressure difference and viscosity are considered, and go/no-go leak rates are described.</div></div>

Manifestation of Corneal Wound Gap during Cataract Surgery: A Case Report

Significance: Intraoperative AS-OCT showed great advantages in the treatment of the patient with traumatic cataract and corneal perforation, and could be used to real-time monitor the changes of corneal wound and the IOL position. Purpose: To report the change of corneal wound in a patient with traumatic cataract and corneal perforation during the anterior segment-OCT-assisted (ASOCT- assisted) cataract surgery. Case Presentation: A 48-year-old male patient, whose right eye was injured by a steel wire two months ago, presented with traumatic cataract and corneal perforation. When he was referred to our hospital, the corneal epithelium and part of anterior stroma at the laceration had healed. Therefore, the corneal laceration was not sutured, and AS-OCT was conducted to monitor the corneal laceration and assess the IOL position during cataract surgery. The laceration maintained closed, and no liquid leakage through corneal laceration was found throughout the surgical operation. IOL was placed into the capsular bag, and the visual acuity of the affected eye recovered to 3/10 postoperatively. Conclusions: Intraoperative AS-OCT could be used to real-time monitor the changes of corneal wound and the IOL position, and showed a significant advantage in the treatment of the eye with traumatic cataract and corneal perforation