The relaxation zone behind normal shock waves in a dusty reacting gas. Part 2. Diatomic gases

1984 ◽  
Vol 31 (1) ◽  
pp. 115-140 ◽  
Author(s):  
O. Igra ◽  
G. Ben-Dor
Keyword(s):  
Shock Wave ◽  
Heat Capacity ◽  
Shock Front ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Thermal Relaxation ◽  
Nitrogen Gas ◽  
Relaxation Length ◽  
Relaxation Zone ◽  
Post Shock

The propagation of a strong normal shock wave into a quiescent mixture of nitrogen gas seeded with small, spherical inert dust particles is studied. While crossing the shock front, the gaseous phase of the suspension experiences a sudden change in temperature, pressure, density and velocity. (These changes can easily be evaluated using the Rankine-Hugoniot relations.) The solid phase of the suspension (dust) is initially unaffected by the shock wave. As a result, immediately behind the shock front, one phase of the suspension (the nitrogen gas) is in a state of relatively high temperature and low velocity while the other (the dust) is in a state of relatively low temperature and high velocity. Owing to these differences in temperature and velocity, intense heat transfer and viscous interactions between the two phases take place leading eventually to a new state of equilibrium that is reached farther downstream of the shock front. The flow field where these interactions take place, the relaxation zone, is solved numerically. It is shown that the spatial extent of this zone is strongly affected by the mass concentration of the dust in the suspenson and its physical properties (size, density and specific-heat capacity). These parameters also affect the post-shock equilibrium suspension properties. It was found that increasing the dust concentration results in a shorter kinematic relaxation zone, higher post-shock suspension pressure, density and temperature, and lower velocity, as compared to a similar pure-gas case. Increasing the dust particle density or its diameter results in a longer relaxation zone and a higher post-shock equilibrium suspension pressure, density and temperature. Changes in the dust specific-heat capacity affect the extent at the thermal relaxation length and the suspension temperature and density; they do not affect the extent of the kinematic relaxation length or the post-shock suspension pressure and velocity. For the range of dust concentration, size, density, specific-heat capacity and shock-wave Mach number investigated, the kinematic relaxation zone is always longer than the thermal relaxation zone.

FALSIFICATIONS OF POISSON ADIABATE, HUGONIO ADIABATE, LAPLACE SOUND SPEEDS. MODERNIZATION OF FOUNDATIONS OF THERMODYNAMICS

2020 ◽  
Vol 5 (333) ◽  
pp. 58-67
Author(s):  
K.B. Jakupov ◽  
Keyword(s):  
Shock Wave ◽  
Heat Capacity ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Speed Of Sound ◽  
Constant Pressure ◽  
Energy Balance Equation ◽  
Ideal Gas ◽  
Constant Volume ◽  
Capacity Coefficient

The inequality of the universal gas constant of the difference in the heat capacity of a gas at constant pressure with the heat capacity of a gas at a constant volume is proved. The falsifications of using the heat capacity of a gas at constant pressure, false enthalpy, Poisson adiabat, Laplace sound speed, Hugoniot adiabat, based on the use of the false equality of the universal gas constant difference in the heat capacity of a gas at constant pressure with the heat capacity of a gas at a constant volume, have been established. The dependence of pressure on temperature in an adiabatic gas with heat capacity at constant volume has been established. On the basis of the heat capacity of a gas at a constant volume, new formulas are derived: the adiabats of an ideal gas, the speed of sound, and the adiabats on a shock wave. The variability of pressure in the field of gravity is proved and it is indicated that the use of the specific coefficient of ideal gas at constant pressure in gas-dynamic formulas is pointless. It is shown that the false “basic formula of thermodynamics” implies the falseness of the equation with the specific heat capacity at constant pressure. New formulas are given for the adiabat of an ideal gas, adiabat on a shock wave, and the speed of sound, which, in principle, do not contain the coefficient of the specific heat capacity of a gas at constant pressure. It is shown that the well-known equation of heat conductivity with the gas heat capacity coefficient at constant pressure contradicts the basic energy balance equation with the gas heat capacity coefficient at constant volume.

The relaxation zone behind normal shock waves in a reacting dusty gas. Part 1. Monatomic gases

1982 ◽  
Vol 27 (3) ◽  
pp. 377-395 ◽  
Author(s):  
G. Ben-Dor ◽  
O. Igra
Keyword(s):  
Shock Waves ◽  
Thermal Relaxation ◽  
Normal Shock ◽  
Dust Particles ◽  
Relaxation Length ◽  
Degree Of Ionization ◽  
Relaxation Zone ◽  
Post Shock ◽  
Free Case ◽  
Mach Numbers

The conservation equations for a suspension composed of an ionized gas and small solid dust particles are formulated and solved numerically. Such flows can be found downstream of strong normal shock waves propagating into dusty gases. The solution indicates that the presence of the dust has a significant effect on the post-shock flow field. Owing to the dust, the relaxation zone will be longer than in the pure plasma case; the equilibrium values for the suspension pressure and density will be higher than in the dust-free case, while the obtained values for the temperature, degree of ionization and velocity will be lower. The numerical solution was executed for shock Mach numbers ranging from 10 to 17. It was found that the thermal relaxation length for the plasma decreases rapidly with increasing shock Mach number, while the thermal relaxation length for the suspension mildly increases with increasing M. The kinematic relaxation length passes through a pronounced maximum at i M = 12·5. Throughout the investigated range of Mach numbers, the kinematic relaxation is longer than the suspension thermal relaxation length.

Experimental Study on the Specific Heat Capacity Measurement of Water-Based Al2O3-Cu Hybrid Nanofluid by using Differential Thermal Analysis Method

2019 ◽  
Vol 15 ◽  
Author(s):  
Andaç Batur Çolak ◽  
Oğuzhan Yıldız ◽  
Mustafa Bayrak ◽  
Ali Celen ◽  
Ahmet Selim Dalkılıç ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Thermophysical Properties ◽  
Volume Concentration ◽  
Pure Water ◽  
Heat Capacity Measurement ◽  
Experimental Results ◽  
Hybrid Nanofluid ◽  
Capacity Measurement

Background: Researchers working in the field of nanofluid have done many studies on the thermophysical properties of nanofluids. Among these studies, the number of studies on specific heat are rather limited. In the study of the heat transfer performance of nanofluids, it is necessary to increase the number of specific heat studies, whose subject is one of the important thermophysical properties. Objective: The authors aimed to measure the specific heat values of Al2O3/water, Cu/water nanofluids and Al2O3-Cu/water hybrid nanofluids using the DTA method, and compare the results with those frequently used in the literature. In addition, this study focuses on the effect of temperature and volume concentration on specific heat. Method: The two-step method was used in the preparation of nanofluids. The pure water selected as the base fluid was mixed with the Al2O3 and Cu nanoparticles and Arabic Gum as the surfactant, firstly mixed in the magnetic stirrer for half an hour. It was then homogenized for 6 hours in the ultrasonic homogenizer. Results: After the experiments, the specific heat of nanofluids and hybrid nanofluid were compared and the temperature and volume concentration of specific heat were investigated. Then, the experimental results obtained for all three fluids were compared with the two frequently used correlations in the literature. Conclusion: Specific heat capacity increased with increasing temperature, and decreased with increasing volume concentration for three tested nanofluids. Cu/water has the lowest specific heat capacity among all tested fluids. Experimental specific heat capacity measurement results are compared by using the models developed by Pak and Cho and Xuan and Roetzel. According to experimental results, these correlations can predict experimental results within the range of ±1%.

Development of the room temperature protocol based on room temperature ionic liquids and surfactant ionic liquids for the synthesis of derivatives of 2-amino-thiazoles and thermo-physical analysis of the synthesized derivatives using TGA-DSC.

2020 ◽  
Vol 10 ◽  
Author(s):  
Chandrakant Sarode ◽  
Sachin Yeole ◽  
Ganesh Chaudhari ◽  
Govinda Waghulde ◽  
Gaurav Gupta
Keyword(s):  
Thermal Analysis ◽  
Heat Capacity ◽  
Ionic Liquids ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Room Temperature ◽  
Heat Capacity Data ◽  
General Strategy ◽  
Capacity Data ◽  
Derivatives Of

Aims: To develop an efficient protocol, which involves an elegant exploration of the catalytic potential of both the room temperature and surfactant ionic liquids towards the synthesis of biologically important derivatives of 2-aminothiazole. Objective: Specific heat capacity data as a function of temperature for the synthesized 2- aminothiazole derivatives has been advanced by exploring their thermal profiles. Method: The thermal gravimetry analysis and differential scanning calorimetry techniques are used systematically. Results: The present strategy could prove to be a useful general strategy for researchers working in the field of surfactants and surfactant based ionic liquids towards their exploration in organic synthesis. In addition to that, effect of electronic parameters on the melting temperature of the corresponding 2-aminothiazole has been demonstrated with the help of thermal analysis. Specific heat capacity data as a function of temperature for the synthesized 2-aminothiazole derivatives has also been reported. Conclusion: Melting behavior of the synthesized 2-aminothiazole derivatives is to be described on the basis of electronic effects with the help of thermal analysis. Additionally, the specific heat capacity data can be helpful to the chemists, those are engaged in chemical modelling as well as docking studies. Furthermore, the data also helps to determine valuable thermodynamic parameters such as entropy and enthalpy.

scholarly journals Influence of alkaline modification on selected properties of banana fiber paperbricks

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Abayomi A. Akinwande ◽  
Adeolu A. Adediran ◽  
Oluwatosin A. Balogun ◽  
Oluwaseyi S. Olusoju ◽  
Olanrewaju S. Adesina
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Moisture Absorption ◽  
Water Volume ◽  
Banana Fiber ◽  
Fiber Loading ◽  
Banana Fibers ◽  
Alkaline Modification

AbstractIn a bid to develop paper bricks as alternative masonry units, unmodified banana fibers (UMBF) and alkaline (1 Molar aqueous sodium hydroxide) modified banana fibers (AMBF), fine sand, and ordinary Portland cement were blended with waste paper pulp. The fibers were introduced in varying proportions of 0, 0.5, 1.0 1.5, 2.0, and 2.5 wt% (by weight of the pulp) and curing was done for 28 and 56 days. Properties such as water and moisture absorption, compressive, flexural, and splitting tensile strengths, thermal conductivity, and specific heat capacity were appraised. The outcome of the examinations carried out revealed that water absorption rose with fiber loading while AMBF reinforced samples absorbed lesser water volume than UMBF reinforced samples; a feat occasioned by alkaline treatment of banana fiber. Moisture absorption increased with paper bricks doped with UMBF, while in the case of AMBF-paper bricks, property value was noted to depreciate with increment in AMBF proportion. Fiber loading resulted in improvement of compressive, flexural, and splitting tensile strengths and it was noted that AMBF reinforced samples performed better. The result of the thermal test showed that incorporation of UMBF led to depreciation in thermal conductivity while AMBF infusion in the bricks initiated increment in value. Opposite behaviour was observed for specific heat capacity as UMBF enhanced heat capacity while AMBF led to depreciation. Experimental trend analysis carried out indicates that curing length and alkaline modification of fiber were effective in maximizing the properties of paperbricks for masonry construction.

scholarly journals Effects of SiO2 Nanoparticle Dispersion on The Heat Storage Property of the Solar Salt for Solar Power Applications

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 703
Author(s):  
Zhao Li ◽  
Liu Cui ◽  
Baorang Li ◽  
Xiaoze Du
Keyword(s):  
Heat Capacity ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Heat Storage ◽  
Md Simulations ◽  
Interfacial Thermal Resistance ◽  
Solar Salt ◽  
Salt Ions ◽  
Base Salt ◽  
Storage Property

The effects of SiO2 nanoparticles on the heat storage properties of Solar Salt (NaNO3-KNO3) are studied using experimental and molecular dynamics (MD) simulations. The experiment results show the specific heat capacity of the molten salt-based nanofluids is higher than that of the pure base salt. We focus on the inference regarding the possible mechanisms behind the enhancement of the specific heat capacity which are considered more acceptable by the majority of researchers, the energy and force in the system are analyzed by MD simulations. The results demonstrate that the higher specific heat capacity of the nanoparticle is not the reason leading to the heat storage enhancement. Additionally, the analysis of potential energy and system configuration shows that the other possible mechanisms (i.e., interfacial thermal resistance theory and compressed layer theory) are only superficial. The forces between the nanoparticle atoms and base salt ions construct the constraint of the base salt ions, further forms the interfacial thermal resistance, and the compressed layer around the nanoparticle. This constraint has a more stable state and requires more energy to deform it, leading to the improvement of the heat storage property of nanofluids. Our findings uncover the mechanisms of specific heat capacity enhancement and guide the preparation of molten salt-based nanofluids.

A critical review of specific heat capacity of hybrid nanofluids for thermal energy applications

2021 ◽  
pp. 116890
Author(s):  
Humphrey Adun ◽  
Ifeoluwa Wole-Osho ◽  
Eric C. Okonkwo ◽  
Doga Kavaz ◽  
Mustafa Dagbasi
Keyword(s):  
Heat Capacity ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Thermal Energy ◽  
Critical Review ◽  
Energy Applications ◽  
Hybrid Nanofluids

scholarly journals A simple model for predicting soil temperature in snow-covered and seasonally frozen soil: model description and testing

2004 ◽  
Vol 8 (4) ◽  
pp. 706-716 ◽  
Author(s):  
K. Rankinen ◽  
T. Karvonen ◽  
D. Butterfield
Keyword(s):  
Heat Capacity ◽  
Simple Model ◽  
Soil Temperature ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Frozen Soil ◽  
Model Description ◽  
Freezing And Thawing ◽  
Catchment Scale ◽  
Soil Temperatures

Abstract. Microbial processes in soil are moisture, nutrient and temperature dependent and, consequently, accurate calculation of soil temperature is important for modelling nitrogen processes. Microbial activity in soil occurs even at sub-zero temperatures so that, in northern latitudes, a method to calculate soil temperature under snow cover and in frozen soils is required. This paper describes a new and simple model to calculate daily values for soil temperature at various depths in both frozen and unfrozen soils. The model requires four parameters: average soil thermal conductivity, specific heat capacity of soil, specific heat capacity due to freezing and thawing and an empirical snow parameter. Precipitation, air temperature and snow depth (measured or calculated) are needed as input variables. The proposed model was applied to five sites in different parts of Finland representing different climates and soil types. Observed soil temperatures at depths of 20 and 50 cm (September 1981–August 1990) were used for model calibration. The calibrated model was then tested using observed soil temperatures from September 1990 to August 2001. R2-values of the calibration period varied between 0.87 and 0.96 at a depth of 20 cm and between 0.78 and 0.97 at 50 cm. R2-values of the testing period were between 0.87 and 0.94 at a depth of 20cm, and between 0.80 and 0.98 at 50cm. Thus, despite the simplifications made, the model was able to simulate soil temperature at these study sites. This simple model simulates soil temperature well in the uppermost soil layers where most of the nitrogen processes occur. The small number of parameters required means that the model is suitable for addition to catchment scale models. Keywords: soil temperature, snow model

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