New Type of Smoluchowski Temperature Jump Condition Considering the Viscous Heat Generation

AIAA Journal ◽  
2017 ◽  
Vol 55 (2) ◽  
pp. 474-483 ◽  
Author(s):  
Nam T. P. Le ◽  
Ngoc Anh Vu ◽  
Le Tan Loc
Keyword(s):  
Heat Generation ◽  
Temperature Jump ◽  
Jump Condition ◽  
Viscous Heat ◽  
New Type

Comprehensive Evaluation of a New Type of Smoluchowski Temperature Jump Condition

AIAA Journal ◽  
2018 ◽  
Vol 56 (11) ◽  
pp. 4621-4625 ◽  
Author(s):  
Ashwani Assam ◽  
Nikhil Kalkote ◽  
Nishanth Dongari ◽  
Vinayak Eswaran
Keyword(s):  
Temperature Jump ◽  
Comprehensive Evaluation ◽  
Jump Condition ◽  
New Type

Comprehensive assessment of viscous heat generation in rarefied gas microflows

2021 ◽  
Author(s):  
Nam T. P. Le ◽  
Bang V. Dinh ◽  
Quang L. Dang ◽  
Anh V. Dang ◽  
Y. Q. Nguyen
Keyword(s):  
Heat Generation ◽  
Rarefied Gas ◽  
Comprehensive Assessment ◽  
Viscous Heat ◽  
Gas Microflows

Temperature Prediction of a Used Nuclear Fuel Cask With Different Gas Backfills

2020 ◽  
Author(s):  
Megan Higley ◽  
Mustafa Hadj-Nacer ◽  
Miles Greiner
Keyword(s):  
Heat Generation ◽  
Temperature Jump ◽  
Generation Rate ◽  
Spent Fuel ◽  
Heat Generation Rate ◽  
Ansys Fluent ◽  
Used Nuclear Fuel ◽  
Computational Fluid Dynamics Cfd ◽  
Project Lead ◽  
Low Pressures

Abstract In this work, a two-dimensional (2D) geometrically-accurate model of the TN-32 cask is generated in ANSYS/Fluent to investigate the effect of backfill gases and their pressures on the peak cladding temperature (PCT). This model is similar to the cask being used in high-burnup (HBU) spent fuel data project lead by the Electric Power Research Institute (EPRI). Helium, nitrogen, argon, and water vapor fill gases are investigated at pressures ranging from atmospheric (∼105 Pa) to 100 Pa. Steady-state computational fluid dynamics (CFD) simulations that include the effect of gas rarefaction (temperature-jump) at the gas-solid interfaces are conducted. The PCT as a function of heat generation rate and pressure is reported as well as the heat generation rate that brings the cladding temperature to the radial hydride formation limit. The results show that there are competing effects between the temperature-jump and the thermal conductivity of the gas to increase the fuel rods’ temperature. The low pressures increased the PCT, with the increase being most significant for the helium backfill.

On Temperature Jump Condition for Slip Flow in a Microchannel With Constant Wall Temperature

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Yutaka Asako ◽  
Chungpyo Hong
Keyword(s):  
Boundary Condition ◽  
Viscous Dissipation ◽  
Wall Temperature ◽  
Energy Equation ◽  
Temperature Jump ◽  
Slip Flow ◽  
Jump Condition ◽  
Constant Wall Temperature ◽  
Maximum Heat ◽  
Maximum Heat Transfer

The analytical solution in the fully developed region of a slip flow in a circular microtube with constant wall temperature is obtained to verify the conventional temperature jump boundary condition when both viscous dissipation (VD) and substantial derivative of pressure (SDP) terms are included in the energy equation. Although the shear work term is not included in the conventional temperature jump boundary condition explicitly, it is verified that the conventional temperature jump boundary condition is valid for a slip flow in a microchannel with constant wall temperature when both viscous dissipation and substantial derivative of pressure terms are included in the energy equation. Numerical results are also obtained for a slip flow in a developing region of a circular tube. The results showed that the maximum heat transfer rate decreases with increasing Mach number.

Investigation of non-equilibrium boundary conditions considering sliding friction for micro/nano flows

2019 ◽  
Vol 29 (8) ◽  
pp. 2501-2523
Author(s):  
Ashwani Assam ◽  
Nikhil Kalkote ◽  
Nishanth Dongari ◽  
Vinayak Eswaran
Keyword(s):  
Slip Velocity ◽  
Sliding Friction ◽  
Temperature Jump ◽  
Jump Condition ◽  
Surface Flow ◽  
Pressure Jump ◽  
Gas Flows ◽  
Flow Properties ◽  
Content Type ◽  
Pressure Driven Flow

Purpose Accurate prediction of temperature and heat is crucial for the design of various nano/micro devices in engineering. Recently, investigation has been carried out for calculating the heat flux of gas flow using the concept of sliding friction because of the slip velocity at the surface. The purpose of this study is to exetend the concept of sliding friction for various types of nano/micro flows. Design/methodology/approach A new type of Smoluchowski temperature jump considering the viscous heat generation (sliding friction) has recently been proposed (Le and Vu, 2016b) as an alternative jump condition for the prediction of the surface gas temperature at solid interfaces for high-speed non-equilibrium gas flows. This paper investigated the proposed jump condition for the nano/microflows which has not been done earlier using four cases: 90° bend microchannel pressure-driven flow, nanochannel backward facing step with a pressure-driven flow, nanoscale flat plate and NACA 0012 micro-airfoil. The results are compared with the available direct simulation Monte Carlo results. Also, this paper has demonstrated low-speed preconditioned density-based algorithm for the rarefied gas flows. The algorithm captured even very low Mach numbers of 2.12 × 10−5. Findings Based on this study, this paper concludes that the effect of inclusion of sliding friction in improving the thermodynamic prediction is case-dependent. It is shown that its performance depends not only on the slip velocity at the surface but also on the mean free path of the gas molecule and the shear stress at the surface. A pressure jump condition was used along with the new temperature jump condition and it has been found to often improve the prediction of surface flow properties significantly. Originality/value This paper extends the concept of using sliding friction at the wall for micro/nano flows. The pressure jump condition was used which has been generally ignored by researchers and has been found to often improve the prediction of surface flow properties. Different flow properties have been studied at the wall apart from only temperature and heat flux, which was not done earlier.

Influence of Thermal Conductivity of Lubricant on the THD Characteristics of a Plain Journal Bearing

1991 ◽  
Author(s):  
C. Rajalingham ◽  
B. S. Prabhu ◽  
R. B. Bhat ◽  
G. D. Xistris
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Temperature Variation ◽  
Heat Generation ◽  
Journal Bearing ◽  
Lubricant Film ◽  
Fluid Film ◽  
Adiabatic Conditions ◽  
Viscous Heat ◽  
Hydrodynamic Journal Bearing

Abstract The viscous heat generation in the lubricant film of a hydrodynamic journal bearing causes a rise in temperature of the fluid film. Considering the influence of the temperature variation along and across the film, the performance of a journal bearing is investigated under adiabatic conditions for different values of thermal conductivity of the lubricant. In this analysis, the temperature of the journal surface has been chosen to ensure that there is no net heat transfer from the lubricant The results show that the variation of temperature across the film affects bearing performance significantly and that an increase in lubricant thermal conductivity enhances bearing performance.

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