State of the art on phase change material slurries Youssef, Ziad; Delahaye, Anthony; Huang, Li ...
Energy conversion and management,
January 2013, 2013, 2013-01-00, 20130101, Volume:
65, Issue:
65
Journal Article
Peer reviewed
A bibliographic study on PCM slurries. Clathrate Hydrate slurry, Microencapsulated PCM Slurry, shape-stabilized PCM slurries and Phase Change Material Emulsions. Formation, thermo-physical, ...rheological, heat transfers properties and applications of these four PCS systems. The use of thermal energy storage and distribution based on PCM slurries can improve the refrigerating machine performances.
The interest in using phase change slurry (PCS) media as thermal storage and heat transfer fluids is increasing and thus leading to an enhancement in the number of articles on the subject. In air-conditioning and refrigeration applications, PCS systems represent a pure benefit resulting in the increase of thermal energy storage capacity, high heat transfer characteristics and positive phase change temperatures which can occur under low pressures. Hence, they allow the increase of energy efficiency and reduce the quantity of thermal fluids. This review describes the formation, thermo-physical, rheological, heat transfer properties and applications of four PCS systems: Clathrate hydrate slurry (CHS), Microencapsulated Phase Change Materials Slurry (MPCMS), shape-stabilized PCM slurries (SPCMSs) and Phase Change Material Emulsions (PCMEs). It regroups a bibliographic summary of important information that can be very helpful when such systems are used. It also gives interesting and valuable insights on the choice of the most suitable PCS media for laboratory and industrial applications.
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IMTLJ, KILJ, KISLJ, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The use of a surfactant mixture of natural and synthetic surfactants as additives in stabilizing coal-water slurry (CWS) formed from low rank Indian coals has been explored. The surface activities of ...the synthetic surfactants, hexadecyltrimethyl ammonium bromide (CTAB, cationic surfactant) and sodium dodecyl sulphate (SDS, anionic surfactant) are found to alter when various concentrations of natural surfactant, saponin (non-ionic surfactant) extracted from the fruits of Sapindous laurifolia are added to them independently. A considerable decrease in viscosity of CWS has been observed on the addition of saponin to the synthetic surfactants, CTAB/SDS (at 50:50 (w/w) for saponin:CTAB; 60:40 (w/w) for saponin:SDS systems). The mixture of anionic-nonionic is however, found to be more effective than the mixture of cationic-nonionic surfactants in reducing the apparent viscosity of the mixtures. The surface tension and contact angle data of the mixtures in solution suggest the high surface activity of the mixtures at these ratios. The rheological behaviors of CWS at weight concentrations varying from 55% to 65%wt.%, the static stability test, effect of pH, temperature, etc. have been studied. The slurries follow Bingham plastic behavior within these ranges of concentrations. A qualitative model of interaction of additive with a coal particle at the interface has been suggested.
•The possibility of the use of surfactant mixture in stabilization of coal-water slurry(CWS) has been explored.•The nonionic-anionic surfactant mixture decreases the viscosity more compared to nonionic-cationic surfactant system.•The CWS follows Bingham plastic model in presence of surfactant mixtures.•Rheological measurement data of the CWS suggests the non-Newtonian character of the slurry in the weight concentration.•Range 55–64.8wt.% for nonionic-anionic surfactant system and 55–64.3wt.% for nonionic-cationic surfactant system.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Nowadays, there is a growing concern about the environmental impacts of colored wastewater. Thus, the present work aims the synthesis, characterization and determination of photocatalytic activity of ...iron oxide (Fe
O
) nanocatalyst, evaluating the effect of hybridization with titanium (TiNPs-Fe
O
) and silver (AgNPs-Fe
O
) nanoparticles, on the degradation of Rhodamine B dye (RhB). Nanocatalysts were characterized by XRD, SEM, TEM, FTIR, N
porosimetry (BET/BJH method), zeta potential and DRS. Photocatalytic tests were performed in a slurry reactor, with the nanocatalyst in suspension, using RhB as a target molecule, under ultraviolet (UV) and visible radiation. Therefore, the photocatalytic activity of the nanocatalysts (non-doped and hybridized) was evaluated in these ideal conditions, where the AgNPs-Fe
O
sample showed the best photocatalytic activity with a degradation of 94.1% (k = 0.0222 min
, under UV) and 58.36% (k = 0.007 min
, under visible), while under the same conditions, the TiO
-P25 commercial catalyst showed a degradation of 61.5% (k = 0.0078 min
) and 44.5% (k = 0.0044 min
), respectively. According with the ideal conditions determined, reusability of the AgNPs-Fe
O
nanocatalyst was measured, showing a short reduction (about 8%) of its photocatalytic activity after 5 cycles. Thus, the Fe
O
nanocatalyst can be considered a promising catalyst in the heterogeneous photocatalysis for application in the degradation of organic dyes in aqueous solution.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
In this work, DLVO theoretical analyses between montmorillonite and fine coal under different pH and divalent cations through measuring zeta potentials under corresponding conditions were conducted. ...The zeta potential of coal dramatically decreased from 8.60 to −46.96 mV as the slurry pH increased from 2.87 to 9.99. Conversely, in the same pH range, zeta potential of montmorillonite slightly changed from −24.68 to −37.46 mV, which showed that slurry pH had little effect on the total surface charge of montmorillonite. DLVO theoretical analyses showed that a total negative DLVO interaction energy between coal and montmorillonite over the whole separation distance was obtained at pH 2.8. Meanwhile, the energy barrier went up with the rising pH. At neutral pH, the addition of divalent cations (Ca2+ and Mg2+) both dramatically decreased the zeta potential values of coal and montmorillonite, resulting in a reversal of DLVO interaction energy from positive (repulsion) to negative (attraction). The compressing ability of Ca2+ to electrical double layer of coal was stronger than that of Mg2+, but conversely to montmorillonite. Overall, through zeta potential measurement, it was indicated that the solution pH and divalent cations both decided the interaction between fine coal and montmorillonite through controlling the electrical double layer force. The DLVO calculation results showed that DLVO theory was in good agreement with the reported flotation phenomena and thus was competent to predict the interaction between montmorillonite and fine coal particle in aqueous suspension.
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•Zeta potentials of coal and MMT were measured.•Effects of different pH and cations on coal and MMT surface charge were observed.•DLVO interaction energy between coal and MMT were calculated.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•Ice slurry crystal growth and control of such.•Efficient and reliable ice slurry generation without scrapers.•Low energy consuming mixing devices.•Inexpensive but accurate sensors for measuring the ...ice and additive concentration.•Description of a Propane-CO2-ice slurry refrigeration system.
Ice slurry is an exciting fluid. It is often called a secondary refrigerant or a heat transfer fluid, because it does not evaporate inside the heat exchanger like refrigerants do. But looking at the energy density and the heat transfer characteristics, ice slurry is on eye level with many HFC refrigerants. Ice slurry can be used inside heat exchangers and in direct contact cooling, offering many interesting areas such as fish or produce chilling. In addition, it can be used for pipe cleaning or for pushing (pigging) precious products out of pipes without significant product loss.
Ice slurry has evolved from a niche product into a technology applied in many fields. Nonetheless, developing efficient ice slurry production, effective ice slurry storage and reliable ice and additive concentration measurements as well as crystal growth issues remain challenging tasks for engineers. The paper suggests future research.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Slurry composition has a decisive influence on clogging in fluid supported excavations.•Laboratory results of mixing test and model TBM cutter-head tests are presented.•Increased ...slurry strength may lead to increased clogging of tunnel boring machines.•Pure polymer slurries can combine high slurry resistance with low clogging potential.
Mechanized excavation of tunnels and fabrication of deep foundation elements in soft ground often requires a fluid support of the temporarily created openings. The supporting fluids are generally mixtures of bentonite with water, enhanced by chemical additives for difficult geological conditions. The properties of the slurries are chosen to guarantee the stability of the excavation, in particular providing sufficient support to the coarse grained soil layers. When these are interlaid with clayey layers, excavation can be hindered by clogging problems, requiring time consuming cleaning works and causing construction delays. Clogging is caused by the stickiness of the excavated clay, which can be affected both by the clay mineralogy and the composition of the supporting slurry. The paper investigates these effects by means of a laboratory experimental study using novel stickiness tests: the mixing test and a model TBM cutter-head test. For bentonite slurries, the stickiness of the excavated soil was found to correlate with the shear resistance of the slurry. Therefore, increased slurry strength, while beneficial for excavations in coarse soils, may lead to increased susceptibility to clogging under mixed face conditions. In contrast, some pure polymer slurries can help to combine high slurry resistance with low clogging potential by protecting clay aggregate surface from penetration of water.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
8.
Acidification of animal slurry– a review Fangueiro, David; Hjorth, Maibritt; Gioelli, Fabrizio
Journal of environmental management,
02/2015, Volume:
149
Journal Article
Peer reviewed
Open access
Ammonia emissions are a major problem associated with animal slurry management, and solutions to overcome this problem are required worldwide by farmers and stakeholders. An obvious way to minimize ...ammonia emissions from slurry is to decrease slurry pH by addition of acids or other substances. This solution has been used commonly since 2010 in countries such as Denmark, and its efficiency with regard to the minimization of NH3 emissions has been documented in many studies. Nevertheless, the impact of such treatment on other gaseous emissions during storage is not clear, since the studies performed so far have provided different scenarios. Similarly, the impact of the soil application of acidified slurry on plant production and diffuse pollution has been considered in several studies. Also, the impact of acidification upon combination with other slurry treatment technologies (e.g. mechanical separation, anaerobic digestion …) is important to consider. Here, a compilation and critical review of all these studies has been performed in order to fully understand the global impact of slurry acidification and assess the applicability of this treatment for slurry management.
•Acidification enhances the fertilizer value of slurry.•Acidification do not increase gaseous emissions.•Acidification impacts positively on solid–liquid separation, composting and biogas production.•Lack of data on the long-term impact of acidified slurry application to soil.•Safe acidification of slurry can be promoted by using new additives.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In this study, oxidized and sulfomethylated lignin (OSL) with the charge density of −4.4 meq/g was used as a dispersant for coal water slurry (CWS). The impact of the OSL on CWS having different ...particle sizes was fundamentally investigated. The size of particles greatly influenced the adsorption of OSL on coal particles and the rheology and stability of the CWS. The maximum adsorption of OSL was found to be 0.96 mg/g on coal A having the particle size of 22 μm (coal particles with smallest size). OSL improved the wettability of coal by 5–28%. The interfacial tension between coal particle and OSL was reduced from 17 mN/m to 13 mN/m, and the zeta potential of the suspension dropped from −30 mV to −47 mV when 0.96 mg/g of OSL was adsorbed on coal A. The addition of 64 mg/L of OSL to coal A suspension (50 wt%) reduced its viscosity from 1350 to 520 mPa·s. The stability of coal particles was also improved as the destabilization index of CWS was reduced from 4 to 0.2. These results confirmed that the OSL was an effective dispersant for the coal water slurry.
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•Oxidized sulfomethylated kraft lignin was used as dispersant for coal water slurry.•Adsorption of lignin changed the wettability and zeta potential of coal particles.•Viscosity and stability of coal water slurry were changed via using lignin.•The changes were more dramatic for small coal particles than for large ones.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Electrocatalytic hydrogenation (ECH) of guaiacol was performed in a stirred slurry electrochemical reactor (SSER) using 5 wt % Pt/C catalyst in the cathode compartment. Different pairs of acid ...(H2SO4), neutral (NaCl), and alkaline (NaOH) catholyte–anolyte combinations separated by a Nafion® 117 cation exchange membrane, were investigated by galvanostatic and potentiostatic electrolysis to probe the electrolyte and proton concentration effect on guaiacol conversion, product distribution, and Faradaic efficiency. The acid–acid and neutral–acid pairs were found to be the most effective. In the case of the neutral–acid pair, proton diffusion and migration through the membrane from the anolyte to the catholyte supplies the protons required for ECH. Typically, the two major hydrogenation products were cyclohexanol and 2‐methoxycyclohexanol. However, ECH at constant cathode superficial current density (−182 mA cm−2) and higher temperature (i.e., 60 °C) favored a pathway leading mainly to cyclohexanone. The guaiacol conversion routes were affected by temperature‐ and cathode potential‐dependent surface coverage of adsorbed hydrogen radicals generated through electroreduction of protons.
Electrolyte matching: Electrocatalytic hydrogenation of guaiacol on Pt/C is investigated under mild conditions using a membrane‐divided stirred slurry electrochemical reactor configuration. Different pairs of catholytes and anolytes are studied using either potentiostatic or galvanostatic control, to determine the electrolyte effect on guaiacol conversion, product distribution, and Faradaic efficiency in synergy with the applied current density, electrode potential and temperature.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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