Computation of thermoacoustical and molecular properties of n-hexane, n-heptane, n-dodecane, cyclohexane and toluene at different temperatures

2021 ◽  
Vol 25 (9) ◽  
pp. 29-34
Author(s):  
Ramakant . ◽  
Subhash Chandra Shrivastava ◽  
Shekhar Srivastava

From the experimental values of density and sound speed of five pure organic liquids (n-hexane, n- heptane, n-dodecane, cyclohexane and toluene), radius (r), van der Waals constants (a and b), molecular dimension (d) and nonlinearity parameters B/A were computed at five different temperatures ranging from 283.15 K to 333.15 K. Four different methods (Hartmann, Ballou rule, Johnson et al and Tong-Dong method) were used to compute to the values of B/A. The experimental data of density and sound speed were taken from the study of Romani et al. All the calculated properties were found to vary with temperature.

2011 ◽  
Vol 367 ◽  
pp. 439-448
Author(s):  
U.U. Akonye ◽  
Ogbonna F. Joel

Break time results carried out for 60Ibs/Mgal linear gel at different breaker and activator concentrations with temperatures for gravel pack jobs done in the past was used in this study. Temperature range investigated was from 180oF to 215oF. A mathematical model was developed for break time prediction as a function of temperature and breaker/activator concentrations. The model was regressed with experimental data using the regression tool in Microsoft Excel. Results of the model prediction were validated with experimental data. The model break time predicted showed good agreement with experimental values with less than 2% deviation. The model equation developed will help predict the break time at the various breaker and activator concentrations at different temperatures. This will help in saving time associated with the rigour in actual laboratory experimental design and testing. This will no doubt improve operational efficiency and service quality delivery.


1975 ◽  
Vol 28 (1) ◽  
pp. 63 ◽  
Author(s):  
Jyoti Prakash ◽  
LP Pathak ◽  
MP Hemkar

The Debye-Waller exponents for oc-iron and sodium are calculated at different temperatures using the Behari-Tripathi (1969) modified angular-force model, which takes into account the effect of electron-ion interactions. The computation uses Blackman's sampling technique. The results are compared with existing experimental data. They are found to agree satisfactorily up to a certain temperature, above which they become progressively lower than the corresponding experimental values.


1980 ◽  
Vol 45 (9) ◽  
pp. 2375-2383 ◽  
Author(s):  
Miloš Ševčík ◽  
Tomáš Boublík

The second virial coefficient in systems with permanent and induced multipole interactions was studied by using a statistical-thermodynamics correlation based on the perturbation theory of fluids. Several pair potential combinations of the Lennard-Jones function with different, subsequently more complex anisotropic contributions, were considered; the improvement in the description of intermolecular interactions due to these non-central contributions brought about an improvement in the interpretation of experimental data. The characteristic dependence of the parameters ε/k on σ at different temperatures was obtained for all of the three systems studied (Ar, CH4 and CH3F). It was found that if experimental values of the second virial coefficient of methyl fluoride are correlated by a relation derived from the Stockmayer potential, two sets of the ε/k and σ can be employed.


The analysis of the previous results of the study on concrete stress-strain behavior at elevated temperatures has been carried out. Based on the analysis, the main reasons for strength retrogression and elastic modulus reduction of concrete have been identified. Despite a significant amount of research in this area, there is a large spread in experimental data received, both as a result of compression and tension. In addition, the deformation characteristics of concrete are insufficiently studied: the coefficient of transverse deformation, the limiting relative compression deformation corresponding to the peak load and the almost complete absence of studies of complete deformation diagrams at elevated temperatures. The two testing chambers provided creating the necessary temperature conditions for conducting studies under bending compression and tension have been developed. On the basis of the obtained experimental data of physical and mechanical characteristics of concrete at different temperatures under conditions of axial compression and tensile bending, conclusions about the nature of changes in strength and deformation characteristics have been drawn. Compression tests conducted following the method of concrete deformation complete curves provided obtaining diagrams not only at normal temperature, but also at elevated temperature. Based on the experimental results, dependences of changes in prism strength and elastic modulus as well as an equation for determining the relative deformation and stresses at elevated temperatures at all stages of concrete deterioration have been suggested.


1994 ◽  
Vol 30 (3) ◽  
pp. 91-93 ◽  
Author(s):  
Biljana D. Škrbic ◽  
Mirjana B. Vojinovic-Miloradov

Gas chromatographic unified retention indices of some chlorinated xenobiotic chemicals, as pollutants in waste waters, on OV-101 and SE-30 stationary phases are presented. These values agree well with the corresponding experimental values used in the statistical treaunent of the experimental data.


Recycling ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 2
Author(s):  
Francesco Paolo La Mantia ◽  
Maria Chiara Mistretta ◽  
Vincenzo Titone

In this work, an additive model for the prediction of the rheological and mechanical properties of monopolymer blends made by virgin and reprocessed components is proposed. A polypropylene sample has been reprocessed more times in an extruder and monopolymer blends have been prepared by simulating an industrial process. The scraps are exposed to regrinding and are melt reprocessed before mixing with the virgin polymer. The reprocessed polymer is, then, subjected to some thermomechanical degradation. Rheological and mechanical experimental data have been compared with the theoretical predictions. The results obtained showed that the values of this simple additive model are a very good fit for the experimental values of both rheological and mechanical properties.


2018 ◽  
Vol 183 ◽  
pp. 01054
Author(s):  
Elisha Rejovitzky

The design of protective structures often requires numerical modeling of shock-wave propagation in the surrounding soils. Properties of the soil such as grain-grading and water-fraction may vary spatially around a structure and among different sites. To better understand how these properties affect wave propagation we study how the meso-structure of soils affects their equation of state (EOS). In this work we present a meso-mechanical model for granular materials based on a simple representation of the grains as solid spheres. Grain-grading is prescribed, and a packing algorithm is used to obtain periodic grain morphologies of tightly packed randomly distributed spheres. The model is calibrated by using experimental data of sand compaction and sound-speed measurements from the literature. We study the effects of graingrading and show that the pressures at low strains exhibit high sensitivity to the level of connectivity between grains. At high strains, the EOS of the bulk material of the grains dominates the behavior of the EOS of the granular material.


2018 ◽  
Vol 207 ◽  
pp. 02002
Author(s):  
Yaoke Wang ◽  
Meng Kou ◽  
Wei Ding ◽  
Huan Ma ◽  
Liangshan Xiong

When applying the non-parallel shear zone model to predict the cutting process parameters of carbon steel workpiece, it is found that there is a big error between the prediction results and the experimental values. And also, the former approach to obtain the relevant cutting parameters of the non-parallel shear zone model by applying coordinate transformation to the parallel shear zone model has a theoretical error – it erroneously regards the determinant (|J|) of the Jacobian matrix (J) in the coordinate transformation as a constant. The shape of the shear zone obtained when |J| is not constant is drew and it is found that the two boundaries of the shear zone are two slightly curved surfaces rather than two inclined planes. Also, the error between predicted values and experimental values of cutting force and cutting thrust is slightly smaller than that of constant |J|. A corrected model where |J| is a variable is proposed. Since the specific values of inclination of the shear zone (α, β), the thickness coefficient of the shear zone (as) and the constants related to the material (f0, p) are not given in the former work, a method to obtain the above-mentioned five constants by solving multivariable constrained optimization problem based on experimental data was also proposed; based on the obtained experimental data of AISI 1045 steel workpiece cutting force, cutting thrust, chip thickness, the results of five above-mentioned model constants are obtained. It is found that, compared with prediction from uncorrected model, the cutting force and cutting thrust of AISI 1045 steel predicted by the corrected model with the obtained constants has a better agreement with the experimental values obtained by Ivester.


Author(s):  
Hellismar W. da Silva ◽  
Renato S. Rodovalho ◽  
Marya F. Velasco ◽  
Camila F. Silva ◽  
Luís S. R. Vale

ABSTRACT The objective of this study was to determine and model the drying kinetics of 'Cabacinha' pepper fruits at different temperatures of the drying air, as well as obtain the thermodynamic properties involved in the drying process of the product. Drying was carried out under controlled conductions of temperature (60, 70, 80, 90 and 100 °C) using three samples of 130 g of fruit, which were weighed periodically until constant mass. The experimental data were adjusted to different mathematical models often used in the representation of fruit drying. Effective diffusion coefficients, calculated from the mathematical model of liquid diffusion, were used to obtain activation energy, enthalpy, entropy and Gibbs free energy. The Midilli model showed the best fit to the experimental data of drying of 'Cabacinha' pepper fruits. The increase in drying temperature promoted an increase in water removal rate, effective diffusion coefficient and Gibbs free energy, besides a reduction in fruit drying time and in the values of entropy and enthalpy. The activation energy for the drying of pepper fruits was 36.09 kJ mol-1.


Author(s):  
Mohammad Hemmat Esfe

In the present article, the effects of temperature and nanoparticles volume fraction on the viscosity of copper oxide-ethylene glycol nanofluid have been investigated experimentally. The experiments have been conducted in volume fractions of 0 to 1.5 % and temperatures from 27.5 to 50 °C. The shear stress computed by experimental values of viscosity and shear rate for volume fraction of 1% and in different temperatures show that this nanofluid has Newtonian behaviour. The experimental results reveal that in a given volume fraction when temperature increases, viscosity decreases, but relative viscosity varies. Also, in a specific temperature, nanofluid viscosity and relative viscosity increase when volume fraction increases. The maximum amount of increase in relative viscosity is 82.46% that occurs in volume fraction of 1.5% and temperature of 50 °C. Some models of computing nanofluid viscosity have been suggested. The greatest difference between the results obtained from these models and experimental results was down of 4 percent that shows that there is a very good agreement between experimental results and the results obtained from these models.


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