scholarly journals Thermal effects of nonuniform heating in a nanofluid‐filled annulus: Buoyant transport versus entropy generation

Heat Transfer ◽  
2021 ◽  
Author(s):  
M. Sankar ◽  
H. A. Kumara Swamy ◽  
Younghae Do ◽  
Sebastian Altmeyer
Keyword(s):  
Entropy Generation ◽  
Thermal Effects ◽  
Nonuniform Heating

Entropy Generation Analysis for Nanofluid Flow in Microchannels

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Jie Li ◽  
Clement Kleinstreuer
Keyword(s):  
Reynolds Number ◽  
Entropy Generation ◽  
Thermal Effects ◽  
Pure Water ◽  
Reynolds Numbers ◽  
Computer Simulation Model ◽  
Number Range ◽  
Aspect Ratios ◽  
Reynolds Number Range ◽  
Steady Laminar

Employing a validated computer simulation model, entropy generation is analyzed in trapezoidal microchannels for steady laminar flow of pure water and CuO-water nanofluids. Focusing on microchannel heat sink applications, local and volumetric entropy rates caused by frictional and thermal effects are computed for different coolants, inlet temperatures, Reynolds numbers, and channel aspect ratios. It was found that there exists an optimal Reynolds number range to operate the system due to the characteristics of the two different entropy sources, both related to the inlet Reynolds number. Microchannels with high aspect ratios have a lower suitable operational Reynolds number range. The employment of nanofluids can further minimize entropy generation because of their superior thermal properties. Heat transfer induced entropy generation is dominant for typical microheating systems while frictional entropy generation becomes more and more important with the increase in fluid inlet velocity/Reynolds number.

Thermal Considerations in Lens Regulator Systems

1970 ◽  
Vol 28 ◽  
pp. 358-359
Author(s):  
K.C. Newton
Keyword(s):  
Electron Microscope ◽  
Thermal Effects ◽  
Environmental Control ◽  
Reference Networks ◽  
Better Than

Thermal effects in lens regulator systems have become a major problem with the extension of electron microscope resolution capabilities below 5 Angstrom units. Larger columns with immersion lenses and increased accelerating potentials have made solutions more difficult by increasing the power being handled. Environmental control, component choice, and wiring design provide answers, however. Figure 1 indicates with broken lines where thermal problems develop in regulator systemsExtensive environmental control is required in the sampling and reference networks. In each case, stability better than I ppm/min. is required. Components with thermal coefficients satisfactory for these applications without environmental control are either not available or priced prohibitively.

Direct measurement of electron-diffraction-pattern intensities using an energy loss spectrometer

1989 ◽  
Vol 47 ◽  
pp. 668-669
Author(s):  
A. G. Jackson ◽  
M. Rowe
Keyword(s):  
Thermal Effects ◽  
Dynamic Range ◽  
Scattering Amplitude ◽  
Dynamical Theory ◽  
Site Symmetry ◽  
Proof Of Concept ◽  
Parallel Acquisition ◽  
Kinematic Approximation ◽  
Speed Up ◽  
Structure Calculations

Diffraction intensities from intermetallic compounds are, in the kinematic approximation, proportional to the scattering amplitude from the element doing the scattering. More detailed calculations have shown that site symmetry and occupation by various atom species also affects the intensity in a diffracted beam. [1] Hence, by measuring the intensities of beams, or their ratios, the occupancy can be estimated. Measurement of the intensity values also allows structure calculations to be made to determine the spatial distribution of the potentials doing the scattering. Thermal effects are also present as a background contribution. Inelastic effects such as loss or absorption/excitation complicate the intensity behavior, and dynamical theory is required to estimate the intensity value.The dynamic range of currents in diffracted beams can be 104or 105:1. Hence, detection of such information requires a means for collecting the intensity over a signal-to-noise range beyond that obtainable with a single film plate, which has a S/N of about 103:1. Although such a collection system is not available currently, a simple system consisting of instrumentation on an existing STEM can be used as a proof of concept which has a S/N of about 255:1, limited by the 8 bit pixel attributes used in the electronics. Use of 24 bit pixel attributes would easily allowthe desired noise range to be attained in the processing instrumentation. The S/N of the scintillator used by the photoelectron sensor is about 106 to 1, well beyond the S/N goal. The trade-off that must be made is the time for acquiring the signal, since the pattern can be obtained in seconds using film plates, compared to 10 to 20 minutes for a pattern to be acquired using the digital scan. Parallel acquisition would, of course, speed up this process immensely.

Experimental Study of Thermal Effects in the Sterilization of Disperse Systems

2001 ◽  
Vol 32 (4-6) ◽  
pp. 5
Author(s):  
A. A. Dolinsky ◽  
Yu. A. Shurchkova ◽  
B. I. Basok ◽  
T. S. Ryzhkova
Keyword(s):  
Experimental Study ◽  
Thermal Effects ◽  
Disperse Systems

ENTROPY GENERATION ANALYSIS FOR A PULSATING HEAT PIPE

2013 ◽  
Vol 44 (1) ◽  
pp. 1-30 ◽  
Author(s):  
Sejung Kim ◽  
Yuwen Zhang ◽  
Jongwook Choi
Keyword(s):  
Heat Pipe ◽  
Entropy Generation ◽  
Pulsating Heat Pipe

ENTROPY GENERATION IN BLOOD FLOW WITH HEAT AND MASS TRANSFER FOR THE ELLIS FLUID MODEL

2018 ◽  
Vol 49 (8) ◽  
pp. 747-760 ◽  
Author(s):  
Muhammad Mubashir Bhatti ◽  
M. Ali Abbas ◽  
M. M. Rashidi
Keyword(s):  
Mass Transfer ◽  
Blood Flow ◽  
Heat And Mass Transfer ◽  
Entropy Generation ◽  
Fluid Model
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