Temperature Dependence Of Water Research Articles

Investigation of water heating efficiency in cavitation mode at initial stage of grain molasses preparation

BACKGROUND: Grain molasses are a valuable source of digestible protein and feed sugar for farm animals. At the initial stage of production of this feed mixture, the existing devices and water heating schemes are not effective enough. In this connection, a new device for accelerated heating of passive-type water has been developed.
 AIMS: evaluation of the effectiveness of the cavitator for heating water in the plant for the production of grain molasses.
 MATERIALS AND METHODS: for conducting studies, a cavitator made in the form of a cone with petals, the angle of the solution of which is 168ʹ, is installed in a glass pipe of the injection branch of the water circuit of the plant for the preparation of grain molasses. During the experiments, the petals were installed in the pipe straight or bent 15. Under laboratory conditions, a comparative experiment was carried out to heat water with a volume of 50 liters, starting from its temperature of 20C and through each degree to 30C, both with and without a cavitator. The process efficiency criteria were: time and specific energy consumption of water heating.
 RESULTS: as a result of the conducted studies, the values of the criteria for the efficiency of the water heating process using a cavitatora and without it are established. Linear dependence of water temperature on heating time is obtained. It has been shown that the created cavitation effect behind the base of the cone is not stable, but still more intense behind the cone with straight petals. It is noted that the coefficient of hydraulic resistance for a cavitator with bent by 15 lobes is 10% greater than with straight ones.
 CONCLUSIONS: use of a cavitatora when heating water at the initial stage of preparing grain molasses increases efficiency of the process by 20%.

Water: An Influential Agent for Lanthanide‐Doped Luminescent Nanoparticles in Nanomedicine

AbstractOptimization of lanthanide‐doped luminescent nanoparticles for use in nanomedicine has encountered some difficulties due to the specific properties of water as a solvent. In this review, the current challenges for the adaptation of lanthanide‐doped luminescent nanoparticles to aqueous environments, and promising strategies to optimize their colloidal dispersibility and stability in water and physiological buffers, are summarized. Moreover, the possible luminescence de‐excitation paths caused by water molecule vibrations and how they can be prevented under different measurement conditions are discussed. This review also deals with the latest developments in lanthanide‐doped luminescent nanoparticle design for nanomedicine, to increase the depth at which they can be monitored, which is mainly limited by the absorption bands of water. Furthermore, the anomalous temperature dependence of water and the different effects it has on lanthanide‐doped luminescent nanoparticles in the physiological temperature range are commented on. Finally, a critical opinion on the possible next steps in this field is provided.

Thermal conductivity temperature dependence of water confined in nanoporous silicon

Recently, it has been shown that high density nanoconfined water was the reason of the important enhancement of the effective thermal conductivity up to a factor of 50% of a nanoporous silicon filled with water. In this work, using molecular dynamics simulations, we further investigate the role of the temperature T (from 285 to 360 K) on the thermal conductivity enhancement of nanohybrid porous silicon and water system. Furthermore, by studying and analysing several structural and dynamical parameters of the nanoconfined water, we give physical insights of the observed phenomena. Upon increasing the temperature of the system, the thermal conductivity of the hybrid system increases reaching a maximum for T = 300 K. With this article, we prove the existence of new heat flux channels between a solid matrix and a nanoconfined liquid, with clear signatures both in the radial distribution function, mean square displacements, water molecules orientation, hydrogen bond networks and phonon density of states.

Water self-diffusion in C-S-H: Effect of confinement and temperature studied by molecular dynamics

Despite the recent advances in the understanding of diffusion processes in C-S-H, there are still open questions regarding the pore-size dependence of diffusion and associated activation energy, and the transition from glassy to Fickean dominated dynamics. We perform molecular dynamics simulations in C-S-H with varying pore sizes (spanning interlayer and gel pore sizes) to investigate the pore size and temperature dependence of water and ion diffusion and activation energy. We quantify the finite-size artifacts from these simulations. The transition from glassy to Fickean-dominated dynamics occurs at an interlayer distance of 2.6 nm. In the Fickean regime, an expression using the self-diffusion of bulk water and a single activation energy captures the pore size and temperature dependence of the water self-diffusion in C-S-H. Finally, the anisotropic self-diffusion obtained from the molecular scale is used as input in mean-field homogenization to get gel diffusivity.

Новая методика расчета теплового стока рек при отсутствии данных наблюдений

In the paper, a comparative analysis of previously developed methods for calculating the heat flux of rivers in the absence of gauging-station data are given, and a new method for such calculations is proposed. It is based on the Maps of specific annual heat flux of zonal rivers and empirical dependencies of heat flux on the average height of the catchment area. An example of such a map is the “Map of specific annual heat flux (MT, 109× kJ/km2) of rivers in the northeast of the Asian part of Russia” plotted on the data for the period from 1950/1955 to 2018 and on the basis of data from 112 gauging stations. General recommendations for calculating the annual heat flux of medium-sized rivers that do not have posts, the intra-annual distribution of heat flux, the values of heat flux at the mouths of large rivers are set out in the paper. The values of heat flux calculated for the marine mouths of region large rivers and the sections of seacoasts between these mouths are given as an example of the implementation of the new recommendations. The list of new materials that help calculations includes new maps of average monthly water temperatures (May-October), the dependence of water temperature and heat flux on the average height of the catchment area, the division of the territory of the Northeast Asian part of Russia into 10 altitude-thermal zones, the relationship between heat flux and water runoff, the catchment area of the river and other materials. In total, data from 34 weather stations, 231 posts with water temperatures and 145 posts with water discharges were used in the research.

Feasibility of Reducing Electricity Consumption of Air Conditioning Equipment by Condenser Direct Evaporative Cooling Technology. Example of Case Study in Dubai

The use of air conditioning technology is accompanied by an increase in electricity consumption, which is linked to an intensification of fossil fuel extraction. This in turn calls for developing cooling solutions of higher energy efficiency. The aim of this study is to examine energy consumption reduction of direct evaporative cooling technology for generating cool air in hot-dry climate regions. At the initial stage, already-installed air cooling equipment with a direct evaporative cooling system was studied for the creation of two regression models of electricity consumption representing the “on” and “off” sequences. Water consumption for system operation was taken into consideration. In the following stage, inlet water temperature dependence for pre-cooling purposes for the direct evaporative cooling system was studied. A mathematical model was developed and the subsequent calculations suggested that there is no need to pre-cool water before it enters the system and therefore consume additional energy. Practical application of this study is evaluated based on the case study in Dubai. The results of this study present significant energy saving potential for system operations of the direct evaporative cooling system of approximately 122 MWh per year. The return on investment for the equipment with direct evaporative cooling in case of an office building in Dubai featuring a hot desert climate is around 4.2 years. The purpose of this study is to examine the potential advantage of air cooling equipment with direct evaporative cooling technology compared to cooling equipment without this technology. The results provide the expediency of conducting further research in this area, in particular with regards to analyzing various materials for the adiabatic precooling pads, as well as the possibility of using a newly developed metal precooling pad.

MODELING OF THERMODYNAMIC PARAMETERS OF SOLIDS BY THE ASYMPTOTIC METHOD

In this work to solve the differential equation of heat conduction we use the separation method taking into account the boundary conditions. The solution of the problem is reduced to the Sturm-Liouville theory. There are other well-known methods for solving the differential equation of heat conduction: the operator method, the solution of the heat equation using the Green's function. We propose a method for solving the differential equation of heat conduction by the asymptotic method using the Laplace transform and furtherLaurent expansion of a function for a solid plate. A theoretical dependence of the temperature on time is obtained which has two sections: the initial one is linearand at large times it is nonlinear. Using the asymptotic expansion we propose expressions for determining the coefficient of thermal conductivity of a solid and the coefficient of heat transfer of a solid to the environmentas well as a method for determining the thermodynamic parameters of a solid. An experiment was carried out where a preheated solid is immersed in a calorimetric chamber filled with water of lower temperature. The heated solid gives off heat to the water. With the help of thermocouples the dependence of water temperature on time is obtained, linear and nonlinear sections of temperature changes are determined. Furtherusing the obtained theoretical expressionthe values ​​of the thermal conductivity coefficient of a solid and the heat transfer coefficient of a solid to water are found. It is shown that, according to the model proposed in the work, the experimentally determined values of the thermal conductivity coefficient and specific heat capacity for a copper plate are close to the known tabular values. At the same time, the calculated and tabulated values of the heat transfer coefficient of copper to water have a significant difference, which requires additional research.

A standardized method to measure the longitudinal UV emittance of low-pressure-lamps in dependence of water temperature

Abstract The high level of acceptance of ultraviolet (UV) irradiation for water disinfection in the past decade is due to the development of quality standards, especially for drinking water disinfection in Europe (Austrian Standards Institute, German Standards Institute). The central parts of a UV-disinfection device are the UV lamps. Despite their importance, their characterisation and quality assurance is far from being a matter of course and had not been regulated so far. This holds especially with regard to their temperature behaviour. The UV radiation (UVR) emittance of Mercury-Low-Pressure- and Amalgam-Low-Pressure-lamps (LP-lamps) depends on temperature. Each lamp type has its own optimal temperature where UVR emittance is highest. At lower or higher temperatures, UVR emittance is reduced. Additionally LP-lamps do not emit homogeneously along their length and this emission profile can change with temperature. In this paper, we present a standardized method to measure the UVR emittance of LP-lamps along the length in water in dependence of water temperature. This method has been included in the updated Austrian standard ÖNORM M 5873-1 (2020) and in the new release DIN 19294-1 (2020). With this method, the UVR emittance of LP-lamps can be characterized and different types of lamps can be compared.

Over 13.8% efficiency of organic solar cells fabricated by air-processable spontaneously spreading process through water temperature control

Spontaneously spreading (SS) film process with water substrates in the air (inert free atmosphere) has recently emerged as an effective technique for the fabrication of large-area organic solar cells (OSCs), however, there are limited studies on the process until now. Herein, we carried out an in-depth study on the influence of varying the temperature of the water substrate during the SS process on the quality of the film and performance of two test-bed OSC devices (PM6:ITIC-4F and PM6:Y7). By accounting for the changes in the kinetics and thermodynamics of the evaporation and dissolution of the solvent in water, we observed a striking water temperature dependence of the morphology and OSC performance. Via careful device optimization with the varying water temperatures, we achieved high power conversion efficiencies (PCEs) of 11.13% and 13.83% for PM6:ITIC-4F-and PM6:Y7-based SS-OSCs processed at 25 °C water temperature, respectively. The 13.83% PCE is the hitherto the highest reported value of the air-processed SS-OSCs. The strategy reported herein with which the quality of films can be controlled by simple modulation of the water temperature can promote the utilization of the SS process in the fabrication of scalable devices of various organic semiconductors.

水の温度依存における物性情報の電子化研究：（第１報）全天候センサーの開発研究報告 (J)

水の温度依存における物性情報の電子化研究：（第１報）全天候センサーの開発研究報告 (J)

Electronization study of physical property information in water temperature dependence:

Electronization study of physical property information in water temperature dependence:

Temperature-Dependent Mechanochemical Wear of Silicon in Water: The Role of Si-OH Surfacial Groups.

Mechanochemical wear has attracted much attention due to its critical role in micro/nanodevice applications, reliable microscopy, and ultraprecision manufacturing. As a process of stress-associated chemical reactions, mechanochemical wear strongly depends on temperature; however, the impact mechanism is not fully understood at any length scale. Here, we reported different water-temperature dependence of mechanochemical wear on two typical single crystal silicon (Si) surfaces, involving oxide-covered Si partially terminated with Si-OH groups and oxide-free Si fully terminated with Si-H groups. As the water temperature increased from 10 to 80 °C, the mechanochemical wear of the oxide-covered Si underwent a process from no obvious surface damage to significant material removal but that occurring at all temperatures decreased gradually on the oxide-free Si surface. The opposite temperature-dependence was found to have a strong relation to the growth or degeneration of the Si-OH surfacial groups. The mechanochemical wear on the both Si surfaces decreased with the Si-OH coverage rising, which facilitated the growth of strongly hydrogen-bonded ordered water and then suppressed the chemical reaction between the sliding interfaces. These results can provide new insight into the mechanism of the surrounding temperature affecting the reliable micro/nanodevices, manufacturing, and microscopy.

Hybrid Grating in Reduced-Diameter Fiber for Temperature-Calibrated High-Sensitivity Refractive Index Sensing

We propose and experimentally demonstrate a hybrid grating, in which an excessively tilted fiber grating (Ex-TFG) and a fiber Bragg grating (FBG) were co-inscribed in a reduced-diameter fiber (RDF). The hybrid grating showed strong resonances due to coupling among core mode and a set of polarization-dependent cladding modes. This coupling showed enhanced evanescent fields by the reduced cladding size, thus allowing stronger interaction with the surrounding medium. Moreover, the FBG’s Bragg resonance confined by the thick cladding was exempt from the change of the surrounding medium’s refractive index (RI), and then the FBG can work as a temperature compensator. As a result, the Ex-TFG in RDF promised a highly sensitive RI measurement, with a sensitivity up to ~1224 nm/RIU near the RI of 1.38. Through simultaneous measurement of temperature and RI, the temperature dependence of water’s RI is then determined. Therefore, the proposed hybrid grating with a spectrum of multi-peaks embedded with a sharp Bragg resonance is a promising alternative for the simultaneous measurement of multi-parameters for many RI-based sensing applications.

Water temperature fluctuation patterns in surface waters of the Tatra Mts., Poland

In this study, we aim to characterise natural variability of water temperature in surface waters of the Tatra Mts. and determine the dominant factors controlling its spatial diversity and seasonal patterns. For this purpose, a total of 33 time series of water temperature representing lakes, vaucluse springs and streams were analysed using the continuous wavelet transform (CWT). The periodicity analysis were conducted with the Morlet wavelet on hourly sampled data covering aperiod of 5 years. The principal components analysis (PCA) has been applied to describe the relationships among variables and extract potential sources of water temperature variability. The results showed an extremely high heterogeneity in temporal patterns of water temperature fluctuations among streams when compared to lakes and vaucluse springs. Wavelet analysis of water temperature time series revealed the presence of seven different configurations of periodical patterns. The lowest variability was observed among vaucluse springs that are supplied by groundwaters. Temporal fluctuations of water temperature in lakes contained four different types of oscillations. Streams were among the most diversified in terms of water temperature patterns exhibiting low, medium and high frequency behaviour. The PCA analysis confirmed the dependence of water temperature on weather conditions, catchment characteristics and flow rate explaining 88.97% of the total variability in the data. The results obtained from this study emphasize the importance of continuous data collection for capturing the long-term dynamics and consistent temporal patterns in time series. The study also demonstrates that wavelet analysis is helpful to identify cyclical patterns in time series of water temperature, and therefore may be useful in the classification of thermal regimes in surface waters.

Monitoring of water quality of selected wells in Brno district

Abstract The article deals with two wells in the country of Brno-district (Brčálka well and Well Olšová). The aim of work was monitoring of elementary parameters of water at regular monthly intervals to measure: water temperature, pH values, solubility oxygen and spring yield. According to the client's requirements (Lesy města Brno) laboratory analyzes of selected parameters were done twice a year and their results were compared with Ministry of Health Decree no. 252/2004 Coll.. These parameters: nitrate, chemical oxygen demand (COD), calcium and magnesium and its values are presented in graphs, for ammonium ions and nitrite in the table. Graphical interpretation of spring yields dependence on the monthly total rainfall and dependence of water temperature on ambient temperature was utilized. The most important features of wells include a water source, a landmark in the landscape, aesthetic element or resting and relaxing place. Maintaining wells is important in terms of future generations.

Solar Energy Application for Desalination of Caspian Sea Water

In the paper for supplying drinkable water of Absheron peninsula, solar energy application for desalination process of the Caspian Sea was given. For this purpose three type of solar energy plants were developed and tested for desalination process. At the same moment dependence of water temperature in solar energy plants on time for all, parabolic, parabolic trough and flat-plate solar collector were determined. Then economically and ecologically the process was estimated.

Water-temperature effect on the spectral density of wind gravity waves and on sea-surface roughness

The results of hourly measurements of sea roughness and hydrometeorological parameters, which were automatically taken from special buoys over a long period of time, were used. These buoys were located in the open regions of both the Atlantic and Pacific oceans in different climatic zones; the mean water-surface temperature around the buoys varies from 1–3°C to 26–28°C. In addition to measurement results, the tables contain data on the spectral density of sea roughness for a wide range of frequencies. An analysis of these data, which was made for a short-wave region of the wind-wave spectrum, for the first time revealed a noticeable watertemperature dependence of the spectral density of wind waves within the frequency range 0.30–0.40 Hz, which corresponds to wave lengths of 9-4 m. The presence of such dependence is explained by a rapid temperature change in kinematic sea-water viscosity. Earlier, we indicated the temperature dependence of only very short spectral components that relate to a centimetric wavelength range. The statistical significance of the watertemperature effect on the spectral density of waves of the indicated frequency is supported by the results of a variance analysis. Temperature variations in the parameter of sea-surface roughness, which is determined, first of all, by the energy of the spectral shortwave region, are estimated. Altimetry is the basic method which is used in remotely determining the velocity of near-water wind. This method allows one to obtain records of deviations of the sea surface from the geoid surface and to calculate (on the basis of these records) the spectral density of wave components of almost any frequency. It is known that the wave-spectrum components in the region of low frequencies are almost always affected by ripple. Consequently, the energy of these components is determined not only by wind forcing, and only the components in the range of frequencies exceeding approximately 0.3 Hz are purely windy. Therefore, using the results of sea-surface altimetry in order to determine the velocity of near-water wind, one should use the spectral densities of wave components in this frequency region. The water-temperature dependence of the spectral density of short wind waves is manifested only in a certain frequency interval, which supports this recommendation.

Confinement-induced structural changes of water studied by Raman scattering

The temperature dependence of water confined in the ordered cylindrical nanopores of MCM-41 and SBA-15 materials is studied by means of Raman scattering for different pore sizes covering a diameter range from 2.0 to 8.9 nm. The liquid--solid phase transition temperature of water in confinement can be determined by the analysis of the mode contribution in the OH-stretching region. For pore sizes down to 3 nm, the freezing/melting point depression with decreasing pore size can be consistently described by a modified Gibbs-Thomson equation, with a nonfreezable water layer of 0.6 nm (about two monolayers) close to the pore walls. When the pore size is 2.5 nm or smaller, indication for a first-order phase transition can no longer be found that is in agreement with previously reported differential scanning calorimetry measurements on the same samples. The Raman data further suggest that two spatially separated water phases exist in the smallest pores, i.e., the nonfreezable wall layer and a structurally different water phase in the core of the pores. A distinct tetrahedral hydrogen-bonded network of water molecules is found only in the core part of the pores. In the weakest confinement (8.9-nm pore diameter), the core water is shown to be compatible with crystalline ice with a spectral fingerprint similar to bulk ice. In strong confinement (2.0-nm pore diameter), the core water shows a spectral fingerprint identical to low-density amorphous ice, and there is a gradual transition between these two extremes. These findings suggest that the core part of confined water undergoes considerable structural changes with decreasing pore size, leading us to question recent proposals that aim to extract information about the state of bulk liquid water in the ``no man's land'' from water in confinement.

Acoustic Characteristics of the Snapping Shrimp Sound Observed in the Coastal Sea of Korea

The typical temporal waveforms, spectra, and water-temperature dependence of the snapping shrimp sound in the coastal sea of Korea were investigated. The peak-to-peak source levels of the snapping shrimp sound at three sites in the coastal sea, at water depths of 8, 10, and 40 m, were also investigated. The waveform and dominant frequency response band of the sound were similar to those observed under laboratory conditions. The broad peak frequency components of the normalized average snapping shrimp sound spectra measured in nine different coastal sea areas were differently determined by superposition of the peak frequency components of individual snapping shrimp spectra for the each area. The sound did not significantly affect the ambient noise level at a low seawater temperature (<10 °C). The mean peak-to-peak source levels of the snapping shrimp sound at the sites with water depths of 8 and 10 m were similar, with estimated values of 176 ±3 and 175 ±3 dB (re 1 µPa at 1 m), respectively. However, the estimated mean peak-to-peak source level at the site with a water depth of 40 m was 184 ±2 dB (re 1 µPa at 1 m). The differences in the mean peak-to-peak source levels at the three sites could be caused by the differences in the ambient pressure at the sea bottoms of the sites. For water depths below 10 m, the mean peak-to-peak source levels of the snapping shrimp sound were much lower than those estimated in a previous study, in which the water depth at the experimental site was 6.1 m. On the other hand, the mean peak-to-peak source level at the site with a water depth of 40 m was similar to that estimated in a previous study. This study shows that the mean peak-to-peak source levels of the snapping shrimp sound may change as water depth is largely varied.

Water temperature dependence of single bubble sonoluminescence threshold

Water temperature dependence of single bubble sonoluminescence (SBSL) threshold has been experimentally measured to perform measurements at different temperatures on the very same bubble. Results show lower thresholds, i.e. an easier prime of mechanism, of sonoluminescence at lower water temperatures. Dependence is almost linear at lower temperatures while between 14 °C and about 20 °C the curve changes its slope reaching soon a virtual independence from water temperature above about 20 °C.