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Using molecular simulation, we assess the impact of an electric field on the properties of water, modeled with the SPC/E potential, over a wide range of states and conditions. Electric fields of the order of 0.1 V/Å and beyond are found to have a significant impact on the grand-canonical partition function of water, resulting in shifts in the chemical potential at the vapor-liquid coexistence of up to 20%. This, in turn, leads to an increase in the critical temperatures by close to 7% for a field of 0.2 V/Å, to lower vapor pressures, and to much larger entropies of vaporization (by up to 35%). We interpret these results in terms of the greater density change at the transition and of the increased structural order resulting from the applied field. The thermodynamics of compressed liquids and of supercritical water are also analyzed over a wide range of pressures, leading to the determination of the Zeno line and of the curve of ideal enthalpy that span the supercritical region of the phase diagram. Rescaling the phase diagrams obtained for the different field strengths by their respective critical properties allows us to draw a correspondence between these systems for fields of up to 0.2 V/Å. [ABSTRACT FROM AUTHOR]

When the thermal expansion of water is discussed in school or university lessons, functional relationships are often inferred without considering measurement uncertainties. Moreover, in some learning materials, the goal of experimentation and the experimental setup do not match. This creates the wrong picture of scientific practice. In this article we compare five experimental setups with different complexity to investigate the relationship between heat and volume change of water. We take different goals of experimentation into account, as well as measurement uncertainties. We compare the different experimental setups, show advantages and limitations, and give advises for their implementation in the classroom. By doing so, we demonstrate that thermal expansion can be very well adopted for applying scientific practice in school. It is shown that the more complex the experimental setup, the more precise the quantitative significance of the functional relationship. [ABSTRACT FROM AUTHOR]

Introduction: In bottled beer pasteurization process simulation, continuity, energy and momentum balances use is required, and these mathematical models in non-steady state require of density, viscosity, heat capacity and thermal conductivity values. Some researchers have used thermo physical water properties to estimate those of beer, without performing any analysis that shows that this is reliable. Objective: To validate mathematical models use to estimate the thermo physical water properties, applying statistical techniques that allow them to be compared with models, data and values reported by different authors, to be used later in bottled beer pasteurization process simulation. Materials and methods: For water properties models validation, regression analysis and hypothesis tests were used, from which comparisons between models and reported values were made. Results and Discussion: When comparing means between obtained by models water properties with those obtained by other authors, probability values greater than 0.05 are obtained, so null hypothesis, Ho, is not rejected. So there are no statistically significant differences between analyzed values. Conclusions: It is proposed to use corresponding to water models in beer thermo physical properties estimation, in pasteurization process temperature range, in future simulation studies. [ABSTRACT FROM AUTHOR]

The temperature dependence of the vibrational T1 lifetime of the OD stretch vibration of HDO in H2O ice was measured with femtosecond mid-IR pump-probe spectroscopy. We found an increase of T1 from 480 ± 40 fs at 25 K to 860 ± 60 fs at 265 K. These lifetimes are remarkably shorter than the vibrational lifetime of the OD stretch vibration of HDO in H2O in the liquid phase, which has a value of 1.7 ± 0.1 ps at 274 K and increases to 2.24 ± 0.09 at 343 K. The observed temperature dependence of T1 can be well explained from a relaxation mechanism in which the OD vibration relaxes via energy transfer to the bend-libration combination tones of H2O and HDO. [ABSTRACT FROM AUTHOR]

The electron binding energies and relaxation dynamics of water cluster anions (H2O)n- (11 ≤ n ≤ 80) formed in co-expansions with neon were investigated using one-photon and time-resolved photoelectron imaging. Unlike previous experiments with argon, water cluster anions exhibit only one isomer class, the tightly bound isomer I with approximately the same binding energy as clusters formed in argon. This result, along with a decrease in the internal conversion lifetime of excited (H2O)n- (25 ≤ n ≤ 40), indicates that clusters are vibrationally warmer when formed in neon. Over the ranges studied, the vertical detachment energies and lifetimes appear to converge to previously reported values. [ABSTRACT FROM AUTHOR]

The speed of sound in high-purity water has been measured in the temperature range (253 to 473) K at pressures up to 400 MPa. The experimental technique used was based on a double-path pulse-echo method with a single 5-MHz ultrasound transducer placed between two unequally spaced reflectors. The cell was calibrated in water at T = 298.15 K and p = 1 MPa against the speed of sound given by the 1995 equation-of-state formulation of the International Association for the Properties of Water and Steam (IAPWS-95) which, for that state point, has an uncertainty of 0.005%. Corrections for the effects of temperature and pressure on the path length difference are considered in detail. The estimated expanded relative uncertainty of the speed of sound determined in this work is shown to be between 0.03% and 0.04% at a confidence level of 95%. The density and isobaric specific heat capacity of water have been obtained in the temperature range (253.15 to 473.15) K at pressure up to 400 MPa by thermodynamic integration of the sound-speed data subject to initial values computed from IAPWS-95 on the isobar at p = 0.1 MPa. The speed of sound, density, and isobaric specific heat capacity were compared with IAPWS-95 with corresponding absolute relative deviations within 0.3%, 0.03%, and 1%, respectively at T ≥ 273.15 K and p ≤ 400 MPa; larger deviations, especially for heat capacity, were found at lower temperatures. The results imply that the uncertainties of properties computed from IAPWS-95 may be significantly reduced over the major part of the region investigated in this work. [ABSTRACT FROM AUTHOR]

Integral equation theory is applied to a coarse-grained model of water to study potential of mean force between hydrophobic solutes. Theory is shown to be in good agreement with the available simulation data for methane-methane and fullerene-fullerene potential of mean force in water; the potential of mean force is also decomposed into its entropic and enthalpic contributions. Mode coupling theory is employed to compute self-diffusion coefficient of water as well as diffusion coefficient of a dilute hydrophobic solute; good agreement with molecular dynamics simulation results is found. [ABSTRACT FROM AUTHOR]

The role of the exchange-correlation density functional (PBE, PW91, RevPBE) and of surface relaxation in the determination of the adsorption energies, reaction energy barriers, and reaction rate constants has been analyzed taking water dissociation on Cu(111) surface as a test case. The PBE and PW91 functionals yield similar adsorption geometries and, adsorption and activation energies, but differ significantly from RevPBE results. For each of the functionals tested, surface relaxation was found to have only a minor effect on the calculated (co)adsorption geometries and (co)adsorption energies. The calculated energy barriers for water dissociation are more affected by the functional used, especially in the case of the RevPBE, with obvious implications on the calculated energy barriers and derived reaction rate constants. [ABSTRACT FROM AUTHOR]

ZnO nanoblades and nanoflowers are synthesized using zinc acetate dihydrate Zn(CH3COO)2·2H2O dissolved in distilled water by ultrasonic pyrolysis at 380–500 °C. Thermogravimetry-differential scanning calorimetry, x-ray diffraction, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, Raman spectroscopy, and low-temperature photoluminescence (PL) were used to characterize the thermal properties, crystalline and optical features of the ZnO nanostructures. The results showed that at 400 °C the formation of nanoblades resulted from the simultaneous precipitation and nucleation in zinc acetate precursor. At an elevated temperature of 450 °C, decomposition was almost advanced and thus the size of nanopetal became smaller and aggregates became larger by as much as 60 nm. The formation of aggregates is explained in terms of random nucleation model. Through PL measurement, nanoblade showed a strong near band-edge emission with negligible deep-level emission and free exciton band-gap energy Eg(0)=3.372 eV and Debye temperature β=477±65 K by the fitting curve of free exciton peak as a function of temperature to Varshni equation, Eg(T)=Eg(0)-αT2/(β+T), which are very close to bulk ZnO. [ABSTRACT FROM AUTHOR]

Focuses on the electronic and liquid structures of water and its thermodynamic properties over a wide range of temperature and density based on the ab initio molecular orbital theory combined with the integral equation method of liquid. Decrease in the molecular dipole moments and electronic polarization energies with an increase in temperature and/or density.

Details an integral equation study of a simple point charge model of water for a variety of thermodynamic states ranging from the vapor phase to the undercooled liquid. Good thermodynamics resulting from the use of a hard sphere fluid as reference system to provide the input reference bridge function.

• Chitosan/poly(eyhylene oxide) nanofibers are obtained by electrospinning. • Successful photo-crosslinking of the nanofiber mats is performed. • Morphological and thermal properties are preserved after the irradiation process. • Photo-crosslinking increases the solvent resistance of the nanofiber mats. • Nanofibers retain their nanostructure morphology after water contact. Photo-crosslinked nanofiber mats containing chitosan were obtained through the versatile and promising technology of electrospinning. Due to the challenging processability of chitosan by electrospinning because of its stiffness and polycationic nature, it was blended with easily-spinnable poly(ethylene oxide). The optimum conditions for electrospinning of chitosan/poly(eyhylene oxide) (CS/PEO) blends were selected for further characterization and investigation: the composition of CS/PEO 70/30 mass fraction was chosen as it allowed to produce uniform and defect free electrospun mats formed by fibers with an average diameter of 270 nm. In order to improve the physico-chemical properties (in particular the stability and water resistance) of the electrospun mats, electrospinning was coupled with the fast and eco-friendly technique of photo-crosslinking. The photo-curing reaction of the CS/PEO fibers, as well as the morphology, thermal properties and water resistance of the electrospun mats before and after application of UV irradiation, were investigated. The photo-crosslinking process was optimized in order to fabricate CS/PEO electrospun mats which are resistant to water and thus can enlarge the application of such membranes, especially in biomedical, filtration and food industries. [ABSTRACT FROM AUTHOR]

The study of protein functions attributed to the conformation and fluctuation that are ruled by both the amino acid sequence and thermodynamics requires thermodynamic quantities given by calorimetry using thermometric techniques. The increased need for protein function in different applications requires improvements of measurement systems assessing protein thermodynamics to handle many kinds of samples quickly. We have developed a passive millimeter-wave microscope that allows near-field imaging of thermal radiation, even at temperature below room temperature where passive infrared imaging systems are ineffective. This advantage of our microscope system in combination with low thermal emission property of water ice in the millimeter-wave region enables the characterization of the thermal radiation from the proteins themselves in aqueous solution at a temperature range low enough to freeze water and to trap conformation intermediates in the proteins. Experiments performed at a millimeter-wave frequency of 50 GHz in a temperature range from 130 to 270 K for a 20% bovine serum albumin (BSA) aqueous solution showed a displacement between two conformational states of BSA at a temperature of approximately 190 K as a boundary. Our microscope system using this freeze-trapping method is expected to provide noninvasive thermal images to enable novel high-throughput calorimetry useful for the analysis of protein functions. [ABSTRACT FROM AUTHOR]

The primary heavy oil recovery is low due to the high viscosity and low mobility; hence, conventional thermal enhanced oil recovery methods such as steam flooding are widely applied to increase the oil production. New unconventional method such as microwave assisted gravity drainage (MWAGD) is under study the change the viscosity of the oil by microwave radiation. Different challenges such as heat loss and low efficiency are faced in unconventional thermal recovery methods especially in deep reservoirs. To improve the performance of unconventional methods, nanotechnology can play an important role. Nanomaterials due to their high surface to volume ratio, more heat absorbance, and more conductivity can be used in a novel approach called nanomaterial/microwave thermal oil recovery. In this work, several nanofluids prepared from nanoparticles such as γ-Alumina (γ-Al2O3), Titanium (IV) oxide (TiO2), MgO, and Fe3O4 were used to enhance the oil viscosity reduction in the porous media under MWAGD mechanism. Our tests showed that adding nanoparticles can increase the absorption of microwave radiation in the oil/ water system in the porous media. The magnitude of this increase is related to the type, particle size distribution in base fluid and, concentration of nanoparticles. Aluminum oxide nanoparticle was found to have the greatest effect on thermal properties of water. For example, only 0.05 wt.% of this nanoparticle, improves the alteration in temperature of water for around 100%. This change can affect the oil recovery and changed it from 37% to more than 40% under MWAGD. Hence, our experiments showed that besides other applications of nanotechnology in enhance oil recovery, heavy oil recovery can also be affected by nanomaterials. [ABSTRACT FROM AUTHOR]

Presents illustrative and qualitative applications of the quantum cluster equilibrium (QCE) theory. Demonstration for a wide range of thermodynamic properties of water; Description of a simplified QCE model; Changes in density and other thermal properties; Model deficiencies.

A new set of measures of the limiting effects of a solute on the solvation thermodynamics of water is defined. It is argued that these measures may be used to probe the effect of various solutes on the environment of a water molecule in aqueous solutions. Some numerical examples are presented, and a qualitative comparison with other methods is discussed. [ABSTRACT FROM AUTHOR]

An equation is derived for the free energy difference between water and ice in the subcooled (supercooled) region. The calculated vapor pressure difference between ice and water agrees well with experimental measurements. The free energy difference estimated for water in the form of emulsion droplets and bulk water, although small varies significantly with temperature in the subcooled region and is shown to be proportional to the excess free energy arising from the surface effects inherent to the emulsion systems. The accuracy of emulsion data at temperatures below -20 °C therefore could be much lower than previously assumed. In turn this would distort the anomaly functions and give incorrect critical temperature estimates. [ABSTRACT FROM AUTHOR]

The solid‐state conversion of a 3D lead(II) coordination polymer, [Pb(1,4‐BDC)(H2O)]n (1) microstructures (1,4‐H2BDC = 1,4‐benzenedicarboxylic acid) with PbO7 coordination sphere, was synthesized by a sonochemical process to a 3D [Pb(1,4‐BDC)]n (2) coordination polymer with nanoparticle morphology and the same coordination environment was observed upon thermal treatment and dehydration. The color of this compound did not change during the process. This process is irreversible and compound 2 cannot absorb water again. Adsorption and desorption of water in these lead(II) coordination polymers were studied by IR spectroscopy, thermo gravimetric and differential thermal analyses (TG‐DTA), X‐ray powder diffraction (XRD), and scanning electron microscopy (SEM). [ABSTRACT FROM AUTHOR]

Improved Cooking Stoves (ICSs) represent the most commonly promoted solution to alleviate the burden associated with the use of traditional biomass in a short-term perspective. However, criticism is raising about the methodologies used for assessing their performance, with a particular focus on laboratory-based testing protocols. One of the key weaknesses of current protocols consists in the inaccurate and biased approach adopted for reporting and statistically analysing test results, which can lead to misleading conclusions about the actual improvements ensured by ICSs. This study proposes a robust procedure to deal with the statistical analysis of small sample sizes, and subsequently verify it through its application to an experimental comparison – based on the Water Boiling Test – between three models of stove. The results show that the current practice based on 3 or 5 replicates often produces biases in the analyses, as at least 13 replicates might be needed to achieve reliable results. Moreover, the study shows how the t-test is in most cases improperly applied, while the proposed procedure allows to deal both with normally and of non-normally distributed data sets in a robust way. In one case, the apparent improvement of an ICS model as compared to the three-stone fire, is refuted by the application of our procedure. [ABSTRACT FROM AUTHOR]

Hybrid PV/Thermal collector is the collector which produced electricity and hot water or hot air at the same time and working as solar cells and solar heaters. This system has been designed to increase the electrical efficiency of the solar cells by withdrawing heat from the solar cells. The present study has been carried out in Kirkuk city (latitude 35.46 and longitude 44.39), water was used as a mean to gain heat from the solar cell by passing it in a thermal exchanger, placed at the lower part of the solar cell, two proto types built to compare the thermal and electrical performance of the hybrid solar collector, the study includes making experiments for the months of (February, March, and April 2017, with a different volume flow rates, three variable designed had been studied, which includes the effect of the reflectance mirrors, glass cover and the slope angle of the lower reflector on the performance of hybrid PV/thermal water collector. The existence of the reflectance mirrors lead to increase the temperature of the solar cell, therefore, its value was (92.7 °C) when using lower and upper mirrors with a glass cover, and (76.1 °C) when using only a lower mirror, and (71.35 °C) without reflecting mirrors. The cell surface decreased to (52.75 °C) of the uncooled solar cell. The existence of the reflectors increases the total values of the thermal and electrical efficiencies. The daily total efficiency in average was a result due to use two reflectors was (81.03%), this means a positive effect on the total efficiency, and the effects of the glass cover on the total efficiency is big, the daily average of the total efficiency with and without glass cover was (58.95%) and (49.97%) respectively, these results are accorded with the results of the previous articles. [ABSTRACT FROM AUTHOR]

Thermal quality in river ecosystems is a fundamental property for the development of biological processes and many of the human activities linked to the aquatic environment. In the future, this property is going to be threatened due to global change impacts, and basin managers will need useful tools to evaluate these impacts. Currently, future projections in temperature modelling are based on the historical data for air and water temperatures, and the relationship with past temperature scenarios; however, this represents a problem when evaluating future scenarios with new thermal impacts. Here, we analysed the thermal impacts produced by several human activities, and linked them with the decoupling degree of the thermal transfer mechanism from natural systems measured with frequency analysis tools (wavelet coherence). Once this relationship has been established we develop a new methodology for simulating different thermal impacts scenarios in order to project them into future. Finally, we validate this methodology using a site that changed its thermal quality during the studied period due to human impacts. Results showed a high correlation (r 2 = 0.84) between the decoupling degree of the thermal transfer mechanisms and the quantified human impacts, obtaining 3 thermal impact scenarios. Furthermore, the graphic representation of these thermal scenarios with its wavelet coherence spectrums showed the impacts of an extreme drought period and the agricultural management. The inter-conversion between the scenarios gave high morphological similarities in the obtained wavelet coherence spectrums, and the validation process clearly showed high efficiency of the developed model against old methodologies when comparing with Nash-Stucliffe criterion. Although there is need for further investigation with different climatic and anthropic management conditions, the developed frequency models could be useful in decision-making processes by managers when faced with future global change impacts. [ABSTRACT FROM AUTHOR]

An attempt to calibrate a conventional oven led to making a measurement of a thermophysical property of water using items found in the author's home. Specifically, the ratio of the energy required to heat water from the melting point to boiling to the energy required to completely boil away the water is found to be 5.7. This may be compared to the standard value of 5.5. The close agreement is not representative of the actual uncertainties in this simple experiment (Fig. 1). Heating water in a microwave oven can let a student apply the techniques of quantitative science based on questions generated by his or her scientific curiosity. [ABSTRACT FROM AUTHOR]

In order to understand the effects of density inversion parameter and Rayleigh number on the fluid motion and heat transfer characteristics of penetrative Rayleigh-Bénard convection in a cylindrical container, a series of large eddy simulations were performed. The working fluid is cold water and Prandtl number is 11.57. Rayleigh number up to 10 11 is considered and the density inversion parameter ranges from 0 to 0.7. The results indicate that the effect of cold plumes on the larger scale circulation gradually diminishes and finally disappears with the increase of density inversion parameter. Furthermore, an increase of the temperature within the bulk region and a decrease of the penetration depth are also certified with the increase of density inversion parameter. With the increase of Rayleigh number, soft and hard turbulent states are successively observed. In the soft turbulence state, the evolution of Nusselt number shows a weak fluctuation, the corresponding histogram has a Gaussian distribution, and the penetration depth increases sharply with the increase of Rayleigh number. In the hard turbulence state, the evolution of Nusselt number presents a much stronger fluctuation than that in the soft turbulence state, the corresponding histogram fits more exponential distribution, and the variation of the penetration depth with Rayleigh number is small. A single power law between the heat transfer efficiency (Nusselt number) and Rayleigh number that covers soft and hard turbulence states is developed for each density inversion parameter. It is found that the average Nusselt number decreases linearly with the increase of density inversion parameter. [ABSTRACT FROM AUTHOR]

The relationships of coefficients of molecule diffusion, viscosity, thermal capacity, thermal conductivity and other properties of water as a function of temperature and pressure have been analyzed. It is shown that the main regularities of changes in water characteristics, including qualitative differences of its behavior from the rest of molecular liquids are stipulated by the peculiarities of covalent and hydrogen bonds. [ABSTRACT FROM AUTHOR]

A two-dimensional hydrodynamic CE-QUAL-W2 model was configured for a deep subtropical river-run reservoir, the Xiluodu Reservoir (XLDR), in China to simulate water temperature in the first two years of impoundment (2013-2014) using measured data as model input. It was calibrated using observed temperature profiles near the dam and the outflow temperatures. Observed daily temperatures at four gauging stations upstream or downstream of XLDR before (2000-2012) and after the impoundment (4 May 2013) were analyzed and fitted with a sine function representing seasonal temperature variation. The fitted annual temperature phase shifts showed no phase delay in XLDR area before the impoundment but revealed a phase delay about 17 days between outflow and inflow after the impoundment, which was not caused by the air temperature variation. The simulated temperatures verified a similar phase delay after the impoundment. The simulated temperatures, water ages, and vertical temperature gradients demonstrated an average metalimnetic deepening rate of 0.49 m/day (average inflow ~4500m³/s) while the largest rate due to massive inflow (~15,000m³/s) was 1.67 m/day. The W2 model was run under hypothetic scenarios of different inflow/outflow rates and outflow withdrawn elevations. The results revealed that greater inflow/outflow rate could lead to higher metalimnetic deepening rate and smaller outflow phase delay, while deeper outflow withdrawn could lead to deeper metalimnion and larger epilimnetic depth. [ABSTRACT FROM AUTHOR]

The relation between the dynamic (e.g., diffusion) and thermodynamic (e.g., entropy) properties of water and water-like liquids has been an active area of research for a long time. Although several studies have investigated the diffusivity and entropy for different systems, these studies have probed either the configurational entropy or the excess entropy of the overall system. In this study, we focus on the entropy of water at a single molecule level at different temperatures. We have used a method developed in our group to calculate the translational and rotational entropy of individual water molecules at various temperatures. We find that the single water translational and rotational entropy exhibit a transition at around 240 K. The translational entropy of individual water molecules shows a consistent variation with change in temperature whereas the variation in the case of rotational entropy is much smaller at different temperatures. We have also calculated diffusion coefficients of water molecules at these temperatures. We find that diffusion also shows the well-known fragile to strong crossover transition at around the same temperature where transition in entropy values has been seen. We have calculated both kinetic and thermodynamic fragilities and crossover points using diffusion and single water translational entropy values. Finally, we correlate the diffusion and translational entropy of individual water molecules using an analog of the Adam-Gibbs relation. Graphical Abstract: : SYNOPSIS Translational and rotational entropy of individual water molecules have been calculated at different temperatures. The thermodynamic fragility in terms of translational entropy has been measured. The thermodynamics have been connected with the dynamics by correlating the diffusion coefficient with translational entropy at different temperatures by using analog of Adam-Gibbs relation. [ABSTRACT FROM AUTHOR]

Natural convection in tilted square cavities filled with water, having one side cooled at 0 °C and the opposite side heated at a temperature ranging between 8 °C and 40 °C, is studied numerically for different cavity widths in the hypothesis of temperature-dependent physical properties, exploring the full range of inclination angles. A computational code based on the SIMPLE-C algorithm is used to solve the system of the mass, momentum and energy transfer governing equations. It is found that, as the inclination angle is increased starting from the cooling-from-below configuration, the heat transfer rate keeps substantially constant until the breakdown of the upper fluid stratification occurs. Thereafter, the heat transfer performance increases steeply up to reaching a peak at an optimal tilting angle, which increases with decreasing both the cavity width and the temperature of the heated wall. Furthermore, when the combination of the cavity width and the temperature of the heated wall is such that at small tilting angles the buoyancy force in the water layer confined between the cooled bottom wall and the density-inversion isotherm is that required for the onset of convection, or just higher, the asymptotic solution is periodical. A number of dimensionless correlations are developed for the prediction of both the optimal tilting angle and the heat transfer rate across the enclosure. [ABSTRACT FROM AUTHOR]

Thermodynamic properties of compressed liquids may be obtained from measurements of the speed of sound by means of thermodynamic integration subject to initial values of density and isobaric specific heat capacity along a single low-pressure isobar. In this paper, we present an analysis of the errors in the derived properties arising from perturbations in both the speed-of-sound surface and the initial values. These errors are described in first order by a pair of partial differential equations that we integrate for the example case of water with various scenarios for the errors in the sound speed and the initial values. The analysis shows that errors in either the speed of sound or the initial values of density that are rapidly oscillating functions of temperature have a disproportionately large influence on the derived properties, especially at low temperatures. In view of this, we have obtained a more accurate empirical representation of the recent experimental speed-of-sound data for water [Lin and Trusler, J. Chem. Phys. 136, (2012) 094511] and use this in a new thermodynamic integration to obtain derived properties including density, isobaric heat capacity and isobaric thermal expansivity at temperatures between (253.15 and 473.15) K at pressures up to 400 MPa. The densities obtained in this way are in very close agreement with those reported by Lin and Trusler, but the isobaric specific heat capacity and the isobaric expansivity both differ significantly in the extremes of low temperatures and high pressures. [ABSTRACT FROM AUTHOR]

High-temperature standard platinum resistance thermometers (HTSPRTs) are used to interpolate the international temperature scale of 1990 (ITS-90), especially for temperatures between the aluminum and the silver points. For this, long-term stability of the HTSPRT is essential. CHINO R800-3L type SPRT, which has a nominal resistance at the triple point of water (TPW) around 0.25 $$\Omega $$ , is the one developed earlier for the interpolation of the ITS-90 at this temperature range. Further development to this previous model has been carried out for the purpose of improving the thermal stability. The improvement was focused on reducing the effect coming from the difference in thermal expansion between platinum wire and the quartz frame on which the platinum wire is installed. New HTSPRTs were made by CHINO Corporation. Some series of tests were carried out at CHINO and at NMIJ. Initial tests after the HTSPRT fabrication were done at CHINO, where thermal cycles between $$500\,{^{\circ }}\hbox {C}$$ and $$980\,{ ^{\circ }}\hbox {C}$$ were applied to the HTSPRTs to see change in the resistances at the TPW $$(R_{\mathrm{TPW}})$$ and at the gallium point $$(R_{\mathrm{Ga}})$$ . Repeated resistance measurements at the silver point $$(R_{\mathrm{Ag}})$$ were performed after completing the thermal cycling test. Before and after every measurement at silver point, $$R_{\mathrm{TPW}}$$ was measured, while before and after every two silver point realization $$R_{\mathrm{Ga}}$$ were measured. After completing this test, the HTSPRTs were transported to NMIJ, where the same repeated measurements at the silver point were done at NMIJ. These were then repeated at CHINO and at NMIJ upon repeated transportation among the institutes, to evaluate some effect due to transportation. This paper reports the details of the above-mentioned tests, the results and the analysis. [ABSTRACT FROM AUTHOR]

Although the thermal conductivity of liquid water is well established, many conflicting values for the thermal conductivity of ice have been reported in the literature. This work demonstrates that the significant differences in the reported ice thermal conductivities can be attributed to differences in the freezing conditions and measurement procedures. In this study, the thermal conductivity of ice was measured over the temperature range of −5 to −40°C using a commercial needle probe. The heating time and data fitting method were first optimized. Then, the effects of the freezing rate, the presence of dissolved gasses in the water, and the presence of a magnetic field during freezing on the thermal conductivity of ice were determined. [ABSTRACT FROM AUTHOR]

The solvation process of water in aqueous solutions of some simple electrolytes is studied. It is found that electrolytes at high concentrations cause the solvation free energy of water to be more negative than in pure liquid water. The initial effect, at very low concentrations, varies markedly from one electrolyte to another. The general trend is that increasing the size of the ions makes the effect of the solute on the solvation free energy of water more positive. Some tentative calculations of the effect of solutes on the entropies and the enthalpies of solvation of water are also presented. [ABSTRACT FROM AUTHOR]

ABSTRACT A novel pyridine-containing aromatic phthalonitrile monomer, 2,6-bis[4-(3,4-dicyanophenoxy)benzoyl]pyridine (BCBP) was synthesized from the nitro displacement of 4-nitrophthalonitrile by the phenoxide of 2,6-bis (4-hydroxybenzoyl)pyridine (BHBP). 4-(Aminophenoxy) phthalonitrile (APPH) was selected to promote the curing reaction, and the curing behavior has been investigated by differential scanning calorimetric (DSC), suggesting a wide processing window about 64 °C. Different curing additive concentrations resulted in polymers with different crosslinking degrees and subsequently influenced the performance of resins. The resulting BCBP polymer exhibited high glass transition temperatures exceeding 400 °C, outstanding thermo-oxidative stability with weight retention of 95% at 530 °C, indicating a significant improvement in thermal properties endowed by pyridine units. Additionally, it also showed a lower overall water absorption after submersion in boiling water for 50 hours. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 3819-3825 [ABSTRACT FROM AUTHOR]

Soil temperatures, water temperatures, and weather parameters were monitored at a variety of locations in the vicinity of King Sejong station, King George Island, Antarctica, during summer 2010-2011. Thermal characteristics of soil and water were analysed using time-series analyses, apparent thermal diffusivity (ATD), and active layer thickness. The temperatures of pond water and nearby seawater showed the distinctive diurnal variations and correlated strongly with solar radiation (r = 0.411-0.797). Soil temperature (0.1-0.3 m depth) also showed diurnal fluctuations that decreased with depth and were directly linked to air temperature (r = 0.513-0.783) rather than to solar radiation; correlation decreased with depth and the time lag in the response increased by 2-3 hours per 0.1 m of soil depth. Owing to the lack of snow cover, summertime soil temperature was not decoupled from air temperature. Estimated ATD was between 0.022 and 29.209 mm2/sec, showed temporal and spatial variations, and correlated strongly with soil moisture content. The maximum estimated active layer thickness in the study area was a 41-70 cm, which is consistent with values reported in the previous work. [ABSTRACT FROM AUTHOR]

Experimental studies were performed on corrugated plate heat exchangers. The corrugated plates’ channel inclination angles for the parallel plates were varied from 0° to 80° in increments of 20° in order to experimentally determine the configuration with the optimum heat transfer rate. The channel spacing was kept constant. The media used in both the hot and the cold channels were water. The temperatures of the two media between which heat was exchanged were 25.4 °C for cold water and 38 °C for hot water. The flow in the heat exchangers was parallel with both the fluids entering from the same side. The flow rate of the hot water was kept constant while that of the cold water was varied. The heat exchangers consisted of ten channels, five for hot water and five for cold water. It was found that the rate of heat transfer increases for all the plate inclination angles as the flow rate of cold water is increased. The overall heat transfer coefficient was observed to be the highest for the 20° inclination angle. The low flow rates of the hot and cold fluids make it a unique study, as the two fluids get more time for heat transfer. The 20° channel inclination angle also has the highest average thermal length. Based on the results, correlations between Nusselt number and Reynolds number were developed. [ABSTRACT FROM AUTHOR]

Statistical polymers and copolymers were firstly synthesized by polymerization of 3,3-bis(azidomethyl) oxetane (BAMO) and 3-azidomethyl-3-methyloxetane (AMMO) in a triisobutylaluminum-water catalytic system, and their physicochemical, physicomechanical, and themochemical properties were studied. It was found that with increasing fraction of poly-AMMO in the BAMO/AMMO copolymers the strength properties of the copolymers enhance and the degree of crystallinity decreases. [ABSTRACT FROM AUTHOR]

An equation of state with near-critical corrections is developed for water (H 2 O) and carbon dioxide (CO 2 ). The equation is constrained by the critical conditions and optimized with highly accurate pressure–volume–temperature ( PVT ) and phase equilibrium data at temperatures from the triple point to 647.096 K and pressures from zero to 80 MPa. The resulting equation is systematically checked in the above P – T range. For H 2 O, the vapor pressures are reproduced within 0.032%, with an average deviation of only 0.005%; the average deviations of the saturated vapor and liquid volumes, and the volumes in the single-phase regions are 0.047%, 0.019% and 0.058%, respectively. The maximum deviations of the above-mentioned volumes are 1.26%, 0.91% and 1.06%, respectively, which are all in the immediate vicinity of the critical point. Below 520 K, the deviations of PVT and saturation properties are all within 0.06%. For subcritical CO 2 , the average and maximum deviations of vapor pressures are 0.011%, 0.077%, respectively; the average deviations of the saturated vapor and liquid volumes, and the volumes in the single-phase regions are 0.099%, 0.058% and 0.126%, respectively. The largest deviations of the above volumes are 0.230%, 0.173% and 0.358%, respectively. For supercritical CO 2 below 650 K, the average volume deviation is 0.080%. The equation also agrees very well with many high-quality density and phase equilibrium data not used to fit the equation. The equation gives excellent prediction of fugacity coefficients, residual enthalpies and entropies and heats of vaporization, and can be extrapolated to 200 MPa for H 2 O, or to 100 MPa for CO 2 . The equation can serve as a good starting point for the thermodynamic modeling of many industrial and geological processes, including carbon capture and sequestration. [ABSTRACT FROM AUTHOR]

Process concepts for making synthesis gas by solar thermochemical cycling have been screened. The produced gas is delivered at 70 °C, 5 bar pressure and with a H 2 /CO ratio of 2.0 which, with moderate adjustments, fit specifications of Fischer–Tropsch synthesis using a cobalt-based catalyst. The cobalt ferrite/alumina assisted hercynite cycle run adiabatically between 1350 and 1330 °C was selected for the study. HYSYS process simulations comprise six process combinations; quenching of hydrogen with CO 2 ; separate solar splitting of water and CO 2 ; vacuum depletion of oxygen in cobalt ferrite; flushing out oxygen with nitrogen produced cryogenically; and flushing with nitrogen from high temperature dense membranes. Calculated energy demand eliminates cryogenic concepts whereas the dense membranes require further study. Most promising is the water-only splitting pathway in combination with CO 2 quench and vacuum oxygen depletion. The alternative with separate H 2 O and CO 2 solar splitting benefits from half the amount of inert CO 2 in the produced syngas and 7% reduction in heliostat size, but suffers from technical challenges with high temperature heat exchangers and severe coking probability; and calculated 7% higher installed cost. The novel chemical quench method limits the use of high temperature heat exchangers to just one for the depleted oxygen. [ABSTRACT FROM AUTHOR]

Water vapor desorption isotherm studies were performed on lignite at the temperature 30, 40 and 50 °C to investigate the behavior of water on coal. For a description of desorption process, a Guggenheim–Anderson–de-Boer (GAB) model provided a good fit. At the monolayer region, the overlapping isotherms at different temperatures could not provide valid data to calculate the isosteric heat by applying the Clausius–Clapeyron equation, and hence the isosteric heat was only determined at the moisture content from 0.125 to 0.280 mg/mg dry coal. Then, the Brunner–Emmet–Teller (BET) theory was applied to calculate the isosteric heat at the moisture content below 0.125 mg/mg dry coal. Net isosteric heat of desorption determined from the isotherms increases from 1.88 kJ/mol in the capillary water to 8.17 kJ/mol at the monolayer region. This increase is most likely that the forces from coal surface act on all types of water in raw lignite, and as the moisture content decreases, the forces are becoming stronger. Besides, with the effect of the interaction among adsorbed water molecules and the bonding force between water molecules and active sites, at the monolayer region, a maximum energy peak appears on the curve of isosteric heat. [ABSTRACT FROM AUTHOR]

Effects of trace PbO on oxide films of Incoloy 800HT were investigated in simulated primary circuit water chemistry of PWR, also with proper Co addition. The trace PbO addition in high temperature water blocked the protective spinel oxides formation of the oxide films of Incoloy 800HT. XPS results indicated that the lead, added as PbO into the high temperature water, shows not only +2 valance but also +4 and 0 valances in the oxide film of 800HT co-operated with Fe, Cr and Ni to form oxides films. Potentiodynamic polarization results indicated that as PbO concentration increased, the current densities of the less protective oxide films of Incoloy 800HT decreased in a buffer solution tested at room temperature. The capacitance results indicated that the donor densities of oxidation film of Incoloy 800HT decreased as trace PbO addition into the high temperature water. [ABSTRACT FROM AUTHOR]

This work presents a dynamic model for a CO2heat pump gas cooler. The gas cooler model is based on the conservation equations of energy, mass, and momentum. Due to the importance of an expansion device and a compressor for heat exchanger modeling, detailed mathematical treatment is also given to those devices. The spatial variations of temperature, pressure, specific volume, and mass flow rate are predicted at each time step. The model is validated by comparing simulation results and experimental data for transient and steady conditions. It observes a reasonably good agreement between these results, with a maximum deviation of 2°C (3.6°F) between the mathematical model and experimental data, with the test data exhibiting a fairly similar trend. The developed model is therefore presented as a useful tool for analyzing the dynamic behavior for the gas cooler of a heat pump operating with CO2. [ABSTRACT FROM AUTHOR]

The release of hydrogen sulfide (H 2 S) during sludge drying is a major environmental problem because of its toxicity to human health. A series of experiments were performed to investigate the mechanisms and factors controlling the H 2 S release. Results of this study show that: (1) the biomass and activity of sulfate-reducing bacteria (SRB) in sludge were the major factors controlling the amount of H 2 S release, (2) the sludge drying temperature had an important effect on both the extent and the timing of H 2 S release from the sludge, and (3) decreasing sludge pH increased the H 2 S release. Based on the findings from this study, a new system that integrates sludge drying and H 2 S gas treatment was developed, by which 97.5% of H 2 S and 99.7% of smoke released from sludge treatments was eliminated. [ABSTRACT FROM AUTHOR]

Describing water transport in concrete is an important issue for the durability assessment of radioactive waste management reinforced concrete structures. Due to the waste thermal output such structures would be submitted to moderate temperatures (up to 80 °C). We have then studied the influence of temperature on water transport within hardened cement pastes of four different formulations. Using a simplified approach (describing only the permeation of liquid water) we characterized the properties needed to describe water transport (up to 80 °C) using dedicated experiments. For each hardened cement paste the results are presented and discussed. [ABSTRACT FROM AUTHOR]

A new ability to quantitatively evaluate the complex pore system of cement pastes, using water sorption isotherms, is used to illuminate: (a) evolutions of microstructure during drying, (b) the mechanisms that control drying shrinkage, and (c) a novel method to compute the original w/c (i.e., water-to-cement ratio, mass basis). Each of these points has significant implications on concrete performance and durability in engineering practice. We show that irreversible changes in the nanostructure during first drying are associated with changes in the pores that empty between ≈ 85-and-45% relative humidity (RH). It is also shown that water in the interlayer space (e.g., similar to clays) of the binding calcium–silicate–hydrate (C–S–H) phase, does not empty until drying below ≈ 25% RH. However, this water, once removed, does not completely re-saturate the pore spaces even at nearly 100% RH — for time scales on the order of weeks. With the ability to specifically identify the volume of pores associated with the C–S–H gel, as opposed to the larger capillary pores and the smaller interlayer spaces, a method for computing the original w/c (and hence cement content), of cementitious material is proposed. These results suggest improved methods for evaluating and modeling the engineering behavior of cement-based materials. [ABSTRACT FROM AUTHOR]

The effect of glycine, dl -alanine and dl -2-aminobutyric acid on the temperature of maximum density of water was determined from density measurements using a magnetic float densimeter. Densities of aqueous solutions were measured within the temperature range from T = (275.65 to 278.65) K at intervals of T = 0.50 K over the concentration range between (0.0300 and 0.1000) mol · kg −1 . A linear relationship between density and concentration was obtained for all the systems in the temperature range considered. The temperature of maximum density was determined from the experimental results. The effect of the three amino acids is to decrease the temperature of maximum density of water and the decrease is proportional to molality according to Despretz equation. The effect of the amino acids on the temperature of maximum density decreases as the number of methylene groups of the alkyl chain becomes larger. The results are discussed in terms of (solute + water) interactions and the effect of amino acids on water structure. [ABSTRACT FROM AUTHOR]