Thermal Expansion Coefficient Of Water Research Articles

Research on Expansion Coefficient Based on Water Temperature Density Regression Function

Based on the regression function of water temperature and water density, two expressions of the thermal expansion coefficient function of water are obtained by integrating and differentiating the function. Compared with the measured data, the theoretical formula of the integral method is in good agreement with the measured accumulated thermal expansion coefficient of water obtained by the cumulative step size. The theoretical formula of the differential method is in good agreement with the measured cumulative thermal expansion coefficient of water obtained by equal step size and variable step size. Therefore, no matter the theoretical formula of the integral method or differential method, it can be used for the thermal expansion coefficient of water with cumulative step size or with finite equal step size or finite variable step size. The theoretical formula of the thermal expansion coefficient of water with integral method and differential method is of high precision and easy to use.

The role of electrostriction in the generation of acoustic waves by optical forces in water

We present semi-analytical solutions describing the spatiotemporal distributions of temperature and pressure inside low-absorbing dielectrics excited by tightly focused laser beams. These solutions are compared to measurements in water associated with variations of the local refractive index due to acoustic waves generated by electrostriction, heat deposition, and the Kerr effect at different temperatures. The experimental results exhibited an excellent agreement with the modeling predictions, with electrostriction being the dominant transient effect in the acoustic wave generation. Measurements at 4.0∘C show that the thermoelastic contribution to the optical signal is significantly reduced due to the low thermal expansion coefficient of water at this temperature.

Thermodynamic Properties of Water in the Temperature Range of 0–100°C and Pressures of 1–9 kbar

Based on a numerical analysis of experimental data on the speed of sound and the thermal expansion coefficient of water, a detailed thermodynamic description of its properties is presented in the pressure range of 1 bar < p < 9 kbar and temperatures of 0 < t < 100°C. This range of pressures and temperatures is considered the one most interesting from the viewpoint of studying the microstructure of water.

Optical wavelength dependence of photoacoustic signal of gold nanofluid

We investigate the optical wavelength dependence of the photoacoustic (PA) signal, detected with bandwidth (BW) in the MHz range, of gold nanospheres (NSs) immersed in water upon illumination with ns laser pulses. We compare the wavelength dependence of the PA signal (within the MHz BW) with the one of the optical absorption coefficient as determined from optical transmission measurements. Thermal boundary conductance (TBC) at the gold-water interface is taken into account, as well as the temperature dependence of the thermal expansion coefficient of water. The effects of NS size and laser pulse duration on the PA signal are also explored. The PA signal is investigated with an opto-thermo-acoustic model considering light absorption in gold NS and in a surrounding water shell.

Photoacoustic detection of photothermal heterodyning: a method for determination of chromophore distances in aqueous solution

When two different chromophores placed close to each other in water are optically excited by continuous light beams with intensities modulated at two different frequencies, the temperature change from heat diffusing from one chromophore affects the magnitude of the thermal expansion coefficient in the region of the other chromophore, owing to the fact that the thermal expansion coefficient of water increases with temperature. Therefore, in addition to two separate linear photoacoustic emission at the sites of each chromophore, the oscillating variations in the thermal expansion coefficient of water means that a heterodyned photoacoustic effect will be generated at the sum and difference of the two modulation frequencies. It is shown here theoretically that the destructive photothermal interference between two chromophores, occurring at certain frequencies for a specific inter-chromophore distance, will give rise to amplitude nulls and thus drastic phase changes in the heterodyned photoacoustic waves, which hints a method that is capable of determining distances between the two chromophores and acts as a photoacoustic analog of Förster resonance energy transfer.

Is water one liquid or two?

The idea that water is a mixture of two distinct states is analyzed in some detail. It is shown that the known compressibility of water is in fact sufficiently small that for a volume of water of size 1 nm3, the density fluctuations are of order 4% of the average density. This is much smaller than the ≈25% density fluctuations that would be required for significant regions of high and low density water to occur on this volume scale. It is also pointed out that the density fluctuations in water are, if anything, smaller than those that occur in other common liquids which do not have the anomalous properties of water. It is shown that if the distribution of density fluctuations is unimodal, the system is in the one-phase region, and if bimodal, it is in the two-phase region. None of the liquid or amorphous phases of water explored in this work give any sign of being in the two-phase region. Existing neutron and X-ray scattering data on water in the amorphous phases, and in the stable liquid phases as a function pressure and temperature, are subject to a new set of empirical potential structure refinement simulations. These simulations are interrogated for their configurational entropy, using a spherical harmonic reconstruction of the full orientational pair correlation function. It is shown that the excess pair entropy derived from this function, plus the known perfect gas contributions, give a reasonable account of the total entropy of water, within the likely errors. This estimated entropy follows the expected declining trend with decreasing temperature. Evidence that higher density water will have higher entropy than lower density water emerges, in accordance with what is expected from the negative thermal expansion coefficient of water at low temperatures. However, this entropy increase is not large and goes through a maximum before declining at yet higher densities and pressures, in a manner reminiscent of what has been previously observed in the diffusion coefficient as a function of pressure. There is no evidence that ambient water can be regarded as patches of high density, high entropy and low density, low entropy liquid, as some have claimed, since high density water has a similar entropy to low density water. There is some evidence that the distinction between these two states will become more pronounced as the temperature is lowered. Extensive discussion of the use of order parameters to describe water structure is given, and it is pointed out that these indices generally cannot be used to infer two-state behavior.

Suppression of photothermal convection of microparticles in two dimensional nanoplasmonic optical lattice

Photothermal convection has been a major obstacle for stable particle trapping in plasmonic optical tweezer at high optical power. Here, we demonstrate a strategy to suppress the plasmonic photothermal convection by using vanishingly small thermal expansion coefficient of water at low temperature. A simple square nanoplasmonic array is illuminated with a loosely Gaussian beam to produce a two dimensional optical lattice for trapping of micro particles. We observe stable particle trapping due to near-field optical gradient forces at elevated optical power at low temperature. In contrast, for the same optical power at room temperature, the particles are convected away from the center of the optical lattice without their accumulation. This technique will greatly increase usable optical power and enhance the trapping capability of plasmonic optical tweezer.

Thermodynamic Analysis of the Two-Liquid Model for Anomalies of Water, HDL-LDL Fluctuations, and Liquid-Liquid Transition.

After reviewing the protocol-dependent properties of HDA, which thermally anneals to LDA, and the data gap over an unusually large T-range between HDA, LDA, and water, we investigate whether or not, despite HDA's ill-defined state and distinction from a glass, the HDL-LDL fluctuations view of the two-liquid model can explain water's anomalous behavior. An analysis of the density, ρ, compressibility, β, heat capacity, Cp, and thermal conductivity, κ, of water over a monotonic (continuous) path bridging this data gap shows the following: (i) Such a path between ρwater at 320 K and ρHDA yields an untenable thermal expansion coefficient of water. (ii) There is neither a continuous path between βwater at 353 K and βHDA, nor between Cp,water at 363 K and Cp,HDA. (iii) The same value of ρwater, of βwater, or of Cp,water at two temperatures separated by a maxima or a minima is incompatible with the HDL-LDL fluctuations view. (iv) κLDA at ∼140 K is about twice that of κ water at 253 K. (v) κHDA at 120 K is incompatible with κwater at T > 320 K. Thus, there is an internal inconsistency between the thermodynamics of HDA seen as a glass and that of water seen as an HDL-LDL mixture, which is incompatible with both the HDL-LDL fluctuations view and the liquid-liquid transition.

Photoacoustic generation by a gold nanosphere: From linear to nonlinear thermoelastics in the long-pulse illumination regime

We investigate theoretically the photoacoustic generation by a gold nanosphere in water in the thermoelastic regime. Specifically, we consider the long-pulse illumination regime, in which the time for electron-phonon thermalisation can be neglected and photoacoustic wave generation arises solely from the thermo-elastic stress caused by the temperature increase of the nanosphere or its liquid environment. Photoacoustic signals are predicted computed based on the successive resolution of a thermal diffusion problem and a thermoelastic problem, taking into account the finite size of the gold nanosphere and the temperature-dependence of the thermal expansion coefficient of water. For sufficiently high illumination fluences, this temperature dependence yields a nonlinear relationship between the photoacoustic amplitude and the fluence. For nanosecond pulses in the linear regime, we show that more than 90 % of the emitted photoacoustic energy is generated in water, and the thickness of the generating layer around the particle scales close to the square root of the pulse duration. Our results demonstrate that the point-absorber model introduced by Calasso et al.[17] significantly overestimates the amplitude of photoacoustic waves in the nonlinear regime. We therefore provide quantitative estimates of a critical energy, defined as the absorbed energy required such that the nonlinear contribution is equal to that of the linear contribution. Our results suggest that the critical energy scales as the volume of water over which heat diffuses during the illumination pulse. Moreover, thermal nonlinearity is shown to be expected only for sufficiently high ultrasound frequency. Finally, we show that the relationship between the photoacoustic amplitude and the equilibrium temperature at sufficiently high fluence reflects the thermal diffusion at the nanoscale around the gold nanosphere.

A laboratory investigation of thermally induced pore pressures in the Callovo-Oxfordian claystone

In the framework of research into radioactive waste disposal, it was decided to investigate the thermally induce pore pressure occurring in the Callovo-Oxfordian claystone (a possible host rock in France). Thermal pore pressures appear in low permeability soils and rocks because the thermal expansion coefficient of water is significantly higher than that of the solid grains.Claystone samples provided to the laboratory are often desaturated, so particular emphasis was put on the saturation of the samples, carried out under in-situ effective stress condition.Thermal pressurization was investigated by performing undrained heating tests while measuring pore pressures changes in a specially adapted thermal isotropic compression cell. Special care was devoted to calibration procedures to account for the effects of the system on pore pressure measurements. The thermal pressurization coefficient measured appeared to change with temperature, mainly because of the changes with temperature of both the water thermal expansion coefficient and the drained compression coefficient of the claystone.

Measuring the Gy:preventing convection in water calorimetry using a low duty cycle modulated beam

Abstract The most fundamental method for determining the absorbed dose to water by radiation beams is by measuring the consequent temperature increase of the water. Water calorimeters used for this purpose are not irradiated uniformly; thus spatial dose gradients within the calorimeter give rise to significant heat transport effects that interfere with the measurement of the small temperature rise associated with radiotherapy doses (e.g. 240 μK/Gy at a typical dose rate of 1 Gy/min). When subjected to periodic exposure to radiation, the calorimeter response (registered as temperature at a point in the water) reaches steady-state oscillation in which effects due to heat conduction and convection may be studied as a function of modulation frequency, so that appropriate correction factors can be derived for desired operating conditions. Theoretical treatment of the behavior is greatly simplified if experimental conditions can be arranged so that convection is negligible. While this is usually done by refrigerating the calorimeter to 4 °C, where the thermal expansion coefficient of water is zero (thus, buoyancy forces due to density fluctuations effectively vanish), we present evidence suggesting that such conditions can be achieved at room temperature by reducing the duty cycle, or effective “on” time of the radiation at a given shutter frequency. Results are presented here in the form of system transfer functions obtained under conditions of 50 and 3.5% duty cycle. Comparison of these measured transfer functions with the output of a three dimensional finite element model indicates that convection is greatly suppressed in the lower duty cycle case. Experimental uncertainty in these measurements is too large to conclude that convection is eliminated altogether, but more extended runs using this technique should enable a more definitive judgment as to whether the simpler conduction corrections alone can be applied.

DNS of buoyancy-dominated turbulent flows on a bluff body using the immersed boundary method

A novel immersed boundary (IB) method has been developed for simulating multi-material heat transfer problem – a cylinder in a channel heated from below with mixed convection. The method is based on a second-order velocity/scalar reconstruction near the IB. A novel algorithm has been developed for the IB method to handle conjugate heat transfer. The fluid–solid interface is constructed as a collection of disjoint faces of control volumes associated to different material zones. Coupling conditions for the material zones have been developed such that continuity and conservation of the scalar flux are satisfied by a second-order interpolation. Predictions of the local Nusselt number on the cylinder surface show good agreement with the experimental data. The effect of the Boussinesq approximation on this problem was also investigated. Comparison with the variable density formulation suggests that, in spite of a small thermal expansion coefficient of water, the variable density formulation in a transitional flow with mixed convection is preferable.

Optical-to-acoustic energy conversion efficiency upon interaction of pulsed laser radiation with a liquid: II. Conversion efficiency measurement by holographic interferometry upon acoustooptic interaction

The efficiency of conversion of pulsed CO2 laser energy to acoustic energy is measured with holographic interferometry. The method suggested is simple and does not require that fringe shifts in the interferogram be converted to local pressure values in the acoustic wave. The efficiency measured for the thermal mechanism of energy conversion is in good agreement with analytical calculations [1] where the temperature dependence of the volume thermal expansion coefficient of water is taken into account.

Relationship between structural order and the anomalies of liquid water.

In contrast to crystalline solids--for which a precise framework exists for describing structure--quantifying structural order in liquids and glasses has proved more difficult because even though such systems possess short-range order, they lack long-range crystalline order. Some progress has been made using model systems of hard spheres, but it remains difficult to describe accurately liquids such as water, where directional attractions (hydrogen bonds) combine with short-range repulsions to determine the relative orientation of neighbouring molecules as well as their instantaneous separation. This difficulty is particularly relevant when discussing the anomalous kinetic and thermodynamic properties of water, which have long been interpreted qualitatively in terms of underlying structural causes. Here we attempt to gain a quantitative understanding of these structure-property relationships through the study of translational and orientational order in a models of water. Using molecular dynamics simulations, we identify a structurally anomalous region--bounded by loci of maximum orientational order (at low densities) and minimum translational order (at high densities)--in which order decreases on compression, and where orientational and translational order are strongly coupled. This region encloses the entire range of temperatures and densities for which the anomalous diffusivity and thermal expansion coefficient of water are observed, and enables us to quantify the degree of structural order needed for these anomalies to occur. We also find that these structural, kinetic and thermodynamic anomalies constitute a cascade: they occur consecutively as the degree of order is increased.

Vertical Penetration of Inclined Heated Water Jets Discharged Downward

In most experimental studies concerning negatively buoyant water jets the buoyancy was produced by density differences due to salt while the temperature of the jet and the ambient fluid was identical. Another method to produce a negatively buoyant water jet is to use different temperatures between the jet and the ambient fluid. However, there are essential differences between thermal and saltwater buoyant jets. In this technical note a modified version of the integral Fan–Brooks model has been used to calculate the vertical penetration of inclined heated water jets discharged downward. The classical initial densimetric Foude number is replaced by an initial effective Froude number based on the thermal expansion coefficient of water. Using the above model, a new equation is derived that predicts the vertical penetration of the thermal jet at a given effective Froude number and discharge angle. This formula reduces to Turner’s equation for vertical jets if the densimetric Froude number is substituted by the effective Froude number.

Horizontal penetration of inclined thermal buoyant water jets

A modified version of the integral Fan-Brooks model has been used to calculate the horizontal penetration of inclined thermal buoyant water jets. The classical densimetric Froude number F o is subsituted by a Froude number F a based on the thermal expansion coefficient of water. Using the above model, a new equation is derived which can predict the horizontal penetration of the thermal jet at a given Froude number F a and discharge angle.