scholarly journals Thermal Analysis of Cornea Heated with Terahertz Radiation

2019 ◽  
Vol 9 (5) ◽  
pp. 917
Author(s):  
Wenquan Liu ◽  
Yuanfu Lu ◽  
Rongbin She ◽  
Guanglu Wei ◽  
Guohua Jiao ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Analysis ◽  
Terahertz Radiation ◽  
Thermal Effects ◽  
Thermal Damage ◽  
Treatment Approach ◽  
Thz Radiation ◽  
Beam Radius ◽  
Corneal Tissue ◽  
Temperature Distributions

We numerically investigate the thermal effects in a cornea illuminated by terahertz radiation. By modifying the bioheat and Arrhenius equations, we studied the heat-transfer and temperature distributions in the corneal tissue, and evaluated the potential thermal damage. The influence of the beam radius and power density are discussed. We also estimated the effective cornea-collagen shrinkage region, and evaluated the degree of thermal damage in the cornea. We expect this work to open up a novel effective and safe thermal-treatment approach based on THz radiation for cornea reshaping in the field of ophthalmology.

Experimental Thermal Analysis of a Mechanical Face Seal

2016 ◽  
Vol 8 (3) ◽  
Author(s):  
K. Ayadi ◽  
N. Brunetière ◽  
B. Tournerie ◽  
A. Maoui
Keyword(s):  
Heat Transfer ◽  
Thermal Analysis ◽  
Thermal Effects ◽  
Inverse Method ◽  
Fluid Pressure ◽  
Operating Conditions ◽  
Mechanical Seal ◽  
Face Seal ◽  
Rotating Speed ◽  
Mechanical Face Seal

An experimental study quantifying the thermal behavior of a mechanical seal is performed. Temperature measurements are obtained using embedded thermocouples within the stator at different locations, and the tests are carried out at different sealed fluid pressures and rotary shaft speeds. Furthermore, an inverse method is used to calculate the heat transfer from the measured local temperatures. The Nusselt number is calculated along the wetted surface as a function of operating conditions; the obtained values are discussed in comparison to previous works. Our results demonstrate that the amplitude of the thermal effects is highly dependent on the operating conditions. The temperature rise being increased by 600% when the rotating speed is raised from 1000 to 6000 rpm and the fluid pressure from 1 to 5 MPa. Moreover, the temperature can vary by several degrees when the distance from the wetted diameter (cooled by convection) and the friction face (heat source) is varied from less than 2 mm.

PHASE EQUILIBRIUM IN THE AS2TE3-TM2TE3 SYSTEM.

2020 ◽  
Vol 5 (8(77)) ◽  
pp. 65-68
Author(s):  
Teymur Mammad Ilyasly ◽  
Rahman Hasanaga Fatullazade ◽  
Zakir Islam Ismailov ◽  
Nigar Nadir Jafarova
Keyword(s):  
Thermal Analysis ◽  
Solid Solution ◽  
Differential Thermal Analysis ◽  
Phase Equilibrium ◽  
Physicochemical Properties ◽  
Thermal Effects ◽  
Isothermal Annealing ◽  
Intermediate Phase ◽  
Physicochemical Analysis ◽  
Two Phases

The synthesis of alloys of the system was carried out stepwise in rotary furnaces. The synthesis mode was selected based on the physicochemical properties of the elementary components. For homogenization, the alloys were subjected to isothermal annealing at 750 and 1275 K, depending on the Tm2Te3 concentration, for 250 h after homogenization of the alloys, they were subjected to physicochemical analysis. The results of differential thermal analysis showed that reversible thermal effects are observed in the alloys of the system. In alloys in a 1: 1 ratio, a new intermediate phase is formed with a composition corresponding to the TmAsTe3 compound. The homogeneity area is observed in the concentration range 52.5-47.5. It was found that in the concentration range 98.5-52.5 Tm2Te3 there are two phases - a mixture of β and of the solid solution, and in the concentration range of 47.51 mol% Tm2Te3 phases and α are in equilibrium. ) 66 The eutectic has coordinates of 11.5 mol Tm2Te3 at a temperature of 575 K.

scholarly journals Photothermal, Photoelectric, and Photothermoelectric Effects in Bi-Sb Thin Films in the Terahertz Frequency Range at Room Temperature

Photonics ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 76
Author(s):  
Mikhail K. Khodzitsky ◽  
Petr S. Demchenko ◽  
Dmitry V. Zykov ◽  
Anton D. Zaitsev ◽  
Elena S. Makarova ◽  
...  
Keyword(s):  
Thin Films ◽  
Terahertz Radiation ◽  
Room Temperature ◽  
Voltage Drop ◽  
Radiation Detection ◽  
Radiation Detectors ◽  
Thz Radiation ◽  
Terahertz Frequency ◽  
Frequency Range ◽  
Terahertz Frequency Range

The terahertz frequency range is promising for solving various practically important problems. However, for the terahertz technology development, there is still a problem with the lack of affordable and effective terahertz devices. One of the main tasks is to search for new materials with high sensitivity to terahertz radiation at room temperature. Bi1−xSbx thin films with various Sb concentrations seem to be suitable for such conditions. In this paper, the terahertz radiation influence onto the properties of thermoelectric Bi1−xSbx 200 nm films was investigated for the first time. The films were obtained by means of thermal evaporation in vacuum. They were affected by terahertz radiation at the frequency of 0.14 terahertz (THz) in the presence of thermal gradient, electric field or without these influences. The temporal dependencies of photoconductivity, temperature difference and voltage drop were measured. The obtained data demonstrate the possibility for practical use of Bi1−xSbx thin films for THz radiation detection. The results of our work promote the usage of these thermoelectric materials, as well as THz radiation detectors based on them, in various areas of modern THz photonics.

Thermal Analysis of Railroad Bearings: Effect of Wheel Heating

2009 ◽  
Author(s):  
Constantine M. Tarawneh ◽  
Arturo A. Fuentes ◽  
Brent M. Wilson ◽  
Kevin D. Cole ◽  
Lariza Navarro
Keyword(s):  
Heat Transfer ◽  
Thermal Analysis ◽  
Roller Bearing ◽  
Railroad Wheel ◽  
Fe Model ◽  
Wheel Pair ◽  
Tapered Roller Bearing ◽  
Excessive Heat ◽  
Tapered Roller ◽  
Railroad Bearings

Catastrophic bearing failure is a major concern for the railroad industry because it can lead to costly train stoppages and even derailments. Excessive heat buildup within the bearing is one of the main factors that can warn of impending failure. A question is often raised regarding the transfer of heat from a wheel during braking and whether this can lead to false setouts. Therefore, this work was motivated by the need to understand and quantify the heat transfer paths to the tapered roller bearing within the railroad wheel assembly when wheel heating occurs. A series of experiments and finite element (FE) analyses were conducted in order to identify the different heat transfer mechanisms, with emphasis on radiation. The experimental setup consisted of a train axle with two wheels and bearings pressed onto their respective journals. One of the wheels was heated using an electric tape placed around the outside of the rim. A total of 32 thermocouples scattered throughout the heated wheel, the axle, and the bearing circumference measured the temperature distribution within the assembly. In order to quantify the heat radiated to the bearing, a second set of experiments was developed; these included, in addition to the axle and the wheel pair, a parabolic reflector that blocked body-to-body radiation to the bearing. The appropriate boundary conditions including ambient temperature, emissivity, and convection coefficient estimates were measured or calculated from the aforementioned experiments. The FE thermal analysis of the wheel assembly was performed using the ALGOR™ software. Experimental temperature data along the radius of the heated wheel, the bearing circumference, and at selected locations on the axle were compared to the results of the FE model to verify its accuracy. The results indicate that the effect of thermal radiation from a hot wheel on the cup temperature of the adjacent bearing is minimal when the wheel tread temperature is at 135°C (275°F), and does not exceed 17°C (31°F) when the wheel tread is at 315°C (600°F).

Study on Thermal Analysis of the Shape of Improved Electric Cooker Liner Based on ANSYS Workbench

2014 ◽  
Vol 487 ◽  
pp. 568-571
Author(s):  
Yan Li Su ◽  
Lei Li ◽  
Wei Guo Han
Keyword(s):  
Thermal Analysis ◽  
Thermal Stress ◽  
Stress Analysis ◽  
Thermal Effects ◽  
The Body ◽  
Total Deformation ◽  
Ansys Workbench

In this paper, a comparative thermal analysis is carried out according to the bottom of HR-FD51 electric cooker liner about a large or small fillet. And then the thermal analysis results are applied to stress analysis as the body loads. The results show that it can reduce thermal stress and total deformation with a large fillet, thereby, improves the lifespan of electric cooker liner and thermal effects as well.

A Numerical Investigation Into the Heat Transfer Performance and Particle Dynamics of a Compressible, Highly Mass Loaded, High Reynolds Number, Particle Laden Flow

2021 ◽  
Author(s):  
Kyle Hassan ◽  
Robert F. Kunz ◽  
David Hanson ◽  
Michael Manahan
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Computational Model ◽  
High Reynolds Number ◽  
Heat Transfer Performance ◽  
Particle Dynamics ◽  
Transfer Performance ◽  
Temperature Distributions ◽  
High Reynolds ◽  
Particle Laden Flow

Abstract In this work, we study the heat transfer performance and particle dynamics of a highly mass loaded, compressible, particle-laden flow in a horizontally-oriented pipe using an Eulerian-Eulerian (two-fluid) computational model. An attendant experimental configuration [1] provides the basis for the study. Specifically, a 17 bar co-flow of nitrogen gas and copper powder are modeled with inlet Reynolds numbers of 3×104, 4.5×104, and 6×104 and mass loadings of 0, 0.5, and 1.0. Eight binned particle sizes were modeled to represent the known powder properties. Significant settling of all particle groups are observed leading to asymmetric temperature distributions. Wall and core flow temperature distributions are observed to agree well with measurements. In high Reynolds number cases, the predictions of the multiphase computational model were satisfactorily aligned with the experimental results. Low Reynolds number model predictions were not as consistent with the experimental measurements.

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