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Properties of Gases and Gas Mixtures
Published in Kavati Venkateswarlu, Engineering Thermodynamics, 2020
The real gases do not obey the assumptions made in the kinetic theory of gases. At very low pressures or very high temperatures, real gas obeys the ideal gas equation as intermolecular attraction and volume occupied by molecules compared to the total volume are not considered at this state. When the pressure increases, intermolecular forces increase and the volume of molecules becomes considerable when compared to that of gas. Thus real gases deviate from the ideal gas equation of state appreciably with an increase in pressure. Van der Waals introduced two correction factors ‘a’ and ‘b’ in the ideal gas equation, first one to account for intermolecular attraction and the second one to account for volume of molecules. The Van der Waals equation is (p+aν2)(ν−b)=RT
Foundations of Heat Transfer
Published in Sadık Kakaç, Yaman Yener, Carolina P. Naveira-Cotta, Heat Conduction, 2018
Sadık Kakaç, Yaman Yener, Carolina P. Naveira-Cotta
Heat conduction in gases and vapors depends mainly on the molecular transfer of kinetic energy of the molecular movement. That is, heat conduction is transmission of kinetic energy by the more active molecules in high temperature regions to the molecules in low molecular kinetic energy regions by successive collisions. According to the kinetic theory of gases, the temperature of an element of gas is proportional to the mean kinetic energy of its constituent molecules. Clearly, the faster the molecules move, the faster they will transfer energy. This implies, therefore, that thermal conductivity of a gas should be dependent on its temperature. For gases at moderately low temperatures, kinetic theory of gases may be used to accurately predict the experimentally observed values. A very simple model of kinetic theory (traffic model) leads to the following approximate relation for gases [14]:
Foundations of Heat Transfer
Published in Yaman Yener, Sadık Kakaç, Heat Conduction, 2018
Heat conduction in gases and vapors depends mainly on the molecular transfer of kinetic energy of the molecular movement. That is, heat conduction is transmission of kinetic energy by the more active molecules in high temperature regions to the molecules in low molecular kinetic energy regions by successive collisions. According to the kinetic theory of gases, the temperature of an element of gas is proportional to the mean kinetic energy of its constituent molecules. Clearly, the faster the molecules move, the faster they will transfer energy. This implies, therefore, that thermal conductivity of a gas should be dependent on its temperature. For gases at moderately low temperatures, kinetic theory of gases may be used to accurately predict the experimentally observed values. A very simple model of kinetic theory (traffic model) leads to the following approximate relation for gases [14]: () k=ρcvV˜λ3
Modeling and simulation of single droplet drying in an acoustic levitator
Published in Drying Technology, 2023
Martin Doß, Nadja Ray, Eberhard Bänsch
According to kinetic theory of gases, the evaporation rate is directly proportional to the thermodynamic non-equilibrium between the saturated vapor pressure and the actual vapor pressure pv at the liquid–gas interface. The local values of jw are thus given by the Hertz–Knudsen equation with Mw being the molar mass of water and the ideal gas constant.[30] To account for the non-volatility of the protein and the salt molecules, we apply Raoult’s law where denotes the water mole fraction of the droplet formulation and pw the saturated vapor pressure of pure water. The latter is given by the Tetens equation with the local droplet temperature in Celsius.
Significance of temperature and pressure on minimum fluidization velocity in a fluidized bed reactor: An experimental analysis
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Rupesh Kumar Singh, Nilesh D. Dhaigude, Arti Sahu, Vishal Chauhan, Gajanan Sahu, Sujan Saha, Prakash D. Chavan
Fluidization experiments have been demonstrated to find out the effect of the temperature at atmospheric pressure on Umf in the FBR. Calcined-clay and Coal-ash were crushed and sieved properly to achieve an average size of the particle of 1.04 and 0.92 mm respectively. Bed materials were utilized to build a 200 mm bed height inside the FBR. Figure 3a reveals the change in Umf with increasing temperature during fluidization phenomena for both bed materials. It was observed that the larger particle of Calcined-clay requires more Umf than the smaller one of Coal-ash. The reason behind this decrease in Umf with increasing temperature may be due to an increase in viscosity of fluidizing medium (air) according to the kinetic theory of gases and law of viscosity, expressed by the following mathematical expression:
Evaporation driven by conductive heat transport
Published in Molecular Physics, 2021
Simon Homes, Matthias Heinen, Jadran Vrabec, Johann Fischer
A classical question concerns the aforementioned BFR, which is also given in Table 2. In order to gather additional information about the BFR at , those simulations had to be carried out again, since relevant data were not given in Ref. [41]. Results obtained from kinetic theory of gases are [75], [76] or [77] and independent on temperature. Based on MD simulations, Lotfi [26] reported for a length of the vapour phase temperature dependent BFR of for , for and for . Since was found to be a function of the interface temperature , cf. Figure 8 and Equation (10), also the BFR only depends on , as can be seen in Figure 9.