scholarly journals Enhancement and maximum in the isobaric specific-heat capacity measurements of deeply supercooled water using ultrafast calorimetry

2021 ◽  
Vol 118 (6) ◽  
pp. e2018379118
Author(s):  
Harshad Pathak ◽  
Alexander Späh ◽  
Niloofar Esmaeildoost ◽  
Jonas A. Sellberg ◽  
Kyung Hwan Kim ◽  
...  
Keyword(s):  
Specific Heat ◽  
Isothermal Compressibility ◽  
Excess Entropy ◽  
Self Diffusion ◽  
Isobaric Specific Heat ◽  
Deep Supercooling ◽  
Long Time ◽  
Similar Temperature ◽  
Specific Temperature ◽  
Heat Capacity Measurements

Knowledge of the temperature dependence of the isobaric specific heat (Cp) upon deep supercooling can give insights regarding the anomalous properties of water. If a maximum in Cp exists at a specific temperature, as in the isothermal compressibility, it would further validate the liquid–liquid critical point model that can explain the anomalous increase in thermodynamic response functions. The challenge is that the relevant temperature range falls in the region where ice crystallization becomes rapid, which has previously excluded experiments. Here, we have utilized a methodology of ultrafast calorimetry by determining the temperature jump from femtosecond X-ray pulses after heating with an infrared laser pulse and with a sufficiently long time delay between the pulses to allow measurements at constant pressure. Evaporative cooling of ∼15-µm diameter droplets in vacuum enabled us to reach a temperature down to ∼228 K with a small fraction of the droplets remaining unfrozen. We observed a sharp increase in Cp, from 88 J/mol/K at 244 K to about 218 J/mol/K at 229 K where a maximum is seen. The Cp maximum is at a similar temperature as the maxima of the isothermal compressibility and correlation length. From the Cp measurement, we estimated the excess entropy and self-diffusion coefficient of water and these properties decrease rapidly below 235 K.

scholarly journals Specific Heat and Transport Functions of Water

2020 ◽  
Vol 21 (2) ◽  
pp. 622 ◽  
Author(s):  
Francesco Mallamace ◽  
Carmelo Corsaro ◽  
Domenico Mallamace ◽  
Enza Fazio ◽  
Sow-Hsin Chen ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Specific Heat ◽  
Atmospheric Pressure ◽  
Thermodynamic Characteristics ◽  
Theoretical Studies ◽  
Molecular Rearrangement ◽  
Self Diffusion ◽  
Water Characteristics ◽  
Isobaric Specific Heat ◽  
Self Diffusion Coefficient

Numerous water characteristics are essentially ascribed to its peculiarity to form strong hydrogen bonds that become progressively more stable on decreasing the temperature. However, the structural and dynamical implications of the molecular rearrangement are still subject of debate and intense studies. In this work, we observe that the thermodynamic characteristics of liquid water are strictly connected to its dynamic characteristics. In particular, we compare the thermal behaviour of the isobaric specific heat of water, measured in different confinement conditions at atmospheric pressure (and evaluated by means of theoretical studies) with its configurational contribution obtained from the values of the measured self-diffusion coefficient through the use of the Adam–Gibbs approach. Our results confirm the existence of a maximum in the specific heat of water at about 225 K and indicate that especially at low temperature the configurational contributions to the entropy are dominant.

Self-diffusion of bimodal suspensions of hydrodynamically interacting spherical particles in shearing flow

1994 ◽  
Vol 281 ◽  
pp. 51-80 ◽  
Author(s):  
Chingyi Chang ◽  
Robert L. Powell
Keyword(s):  
Diffusion Coefficients ◽  
Cluster Size ◽  
Near Field ◽  
Spherical Particles ◽  
Random Structure ◽  
Shearing Flow ◽  
Self Diffusion ◽  
Long Time ◽  
Mobility Matrix ◽  
Many Body Interactions

We study the average mobilities and long-time self-diffusion coefficients of a suspension of bimodally distributed spherical particles. Stokesian dynamics is used to calculate the particle trajectories for a monolayer of bimodal-sized spheres. Hydrodynamic forces only are considered and they are calculated using the inverse of the grand mobility matrix for far-field many-body interactions and lubrication formulae for near-field effects. We determine both the detailed microstructure (e.g. the pair-connectedness function and cluster formation) and the macroscopic properties (e.g. viscosity and self-diffusion coefficients). The flow of an ‘infinite’ suspension is simulated by considering 25, 49, 64 and 100 particles to be one ‘cell’ of a periodic array. Effects of both the size ratio and the relative fractions of the different-sized particles are examined. For the microstructures, the pair-connectedness function shows that the particles form clusters in simple shearing flow due to lubrication forces. The nearly symmetric angular structures imply the absence of normal stress differences for a suspension with purely hydrodynamic interactions between spheres. For average mobilities at infinite Péclet number, Ds0, our simulation results suggest that the reduction of Ds0 as concentration increases is directly linked to the influence of particle size distribution on the average cluster size. For long-time self-diffusion coefficients, Ds∞, we found good agreement between simulation and experiment (Leighton & Acrovos 1987 a; Phan and Leighton 1993) for monodispersed suspensions. For bimodal suspensions, the magnitude of Ds∞, and the time to reach the asymptotic diffusive behaviour depend on the cluster size formed in the system, or the viscosity of the suspension. We also consider the effect of the initial configuration by letting the spheres be both organized (size segregated) and randomly placed. We find that it takes a longer time for a suspension with an initially organized structure to achieve steady state than one with a random structure.

Long-time self-diffusion of charged spherical colloidal particles in parallel planar layers

2014 ◽  
Vol 140 (24) ◽  
pp. 244116 ◽  
Author(s):  
Claudio Contreras-Aburto ◽  
César A. Báez ◽  
José M. Méndez-Alcaraz ◽  
Ramón Castañeda-Priego
Keyword(s):  
Colloidal Particles ◽  
Self Diffusion ◽  
Long Time

scholarly journals Analysis of the Raman Frequency Shifts for the Lattice Modes and Vibrons Related to the Thermodynamic Quantities in the η Phase of Solid Nitrogen

2013 ◽  
Vol 32 (4) ◽  
pp. 383-389 ◽  
Author(s):  
Hamit Yurtseven ◽  
Özge Akay
Keyword(s):  
Thermal Expansion ◽  
Specific Heat ◽  
Isothermal Compressibility ◽  
Raman Frequency ◽  
Thermodynamic Quantities ◽  
Frequency Shifts ◽  
Solid Nitrogen ◽  
Lattice Modes

AbstractThe thermodynamic quantities of the isothermal compressibility, thermal expansion and the specific heat are calculated here as a function of pressure by using the observed Raman frequencies of the lattice modes and vibrons in the η phase of solid nitrogen. The Pippard relations and their spectroscopic modifications are constructed, and the slope dP/dT is deduced from the Raman frequency shifts in this phase of N2. It is shown that the thermodynamic quantities can be predicted from the Raman frequency shifts, in particular, in the η phase of solid nitrogen.

Isobaric Specific Heat Capacity for Al2O3/ Water Ethylene Glycol Mixture Nanofluid

2021 ◽  
pp. 1-22
Author(s):  
Alamir Hassan ◽  
Mohamed Hassan ◽  
Mohamed Shedid
Keyword(s):  
Heat Capacity ◽  
Ethylene Glycol ◽  
Specific Heat ◽  
Base Fluid ◽  
Maximum Deviation ◽  
Experimental Assessment ◽  
Mixture Ratio ◽  
New Correlation ◽  
Isobaric Specific Heat ◽  
Al2o3 Nanoparticle

Abstract Specific heat is a vital characteristic of nanofluids. The present work is an experimental assessment for the isobaric specific heat measurements for the Al2O3 nanoparticle dispersed in a base fluid of different mixture ratio of ethylene glycol and water at 30, 40, 50, and 60 vol%. The experiments were conducted over temperature range from 35 to 105 °C with nanoparticle concentrations of 0.5 to 2.5 vol%. The results indicated that the specific heat of nanofluid decreases as the nanoparticle volume increases and EG ratio increases but increases as the temperature increases. This characteristic demonstrates that the use of nanofluids should be at as high temperature as possible to fulfill a good beneficial effect. A new correlation from the measurements with maximum deviation of 2.2% was found to estimate the specific heat for these nanofluids.

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