Analysis and Mitigation of Sample Heating in Thermoreflectance Microscopy

2005 ◽  
Author(s):  
Andrew C. Miner ◽  
Uttam Ghoshal
Keyword(s):  
Heat Flux ◽  
Temperature Field ◽  
Temperature Rise ◽  
Technical Conference ◽  
Electronic Systems ◽  
Sample Heating ◽  
Large Measurement ◽  
Reflectance Microscopy ◽  
Analytical Expressions ◽  
Thermoreflectance Microscopy

The illumination of a sample when imaged by thermoreflectance thermal microscopy may cause significant heating of the surface. Nonlinearities in the performance of the system being imaged may lead to large measurement induced errors in the observed temperature field. Analytical expressions are presented to estimate the temperature rise and heat flux in a sample. Spatially filtered thermo-reflectance microscopy is introduced as a technique to significantly reduce the incident heat flux without loss of spatial resolution.   This paper was also originally published as part of the Proceedings of the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems.

Self-Heating Modeling of Magnetic Recording Read Head

2005 ◽  
Author(s):  
Y. Yang ◽  
L. Baril ◽  
E. Schreck ◽  
A. Wallash ◽  
M. Asheghi
Keyword(s):  
Magnetic Recording ◽  
Temperature Rise ◽  
Areal Density ◽  
Technical Conference ◽  
Normal Operation ◽  
Electronic Systems ◽  
Element Analysis ◽  
Self Heating ◽  
Read Head ◽  
Gmr Sensor

The performance and reliability of the GMR heads are adversely affected by self-heating due to the aggressive scaling of its dimensions to increase areal density. In this manuscript, the self-heating of the GMR head during the normal operation is investigated. An analytical model is developed to estimate the temperature rise in the GMR sensor due to self-heating for magnetic recording areal densities from 2.8 to 80 Gbits/in2, which agrees well with the FEM simulations. This model is subsequently used to investigate the influence of the GMR head constituent materials’ thermal properties on the device temperature rise. A 3-D finite element analysis was also performed to predict the level of self-heating in lead-overlaid (LOL) design, which agrees well with the experimental data obtained using steady-state and transient measurements.   This paper was also originally published as part of the Proceedings of the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems.

scholarly journals Spray Cooling Trajectory Angle Impact Upon Heat Flux Using a Straight Finned Enhanced Surface

2005 ◽  
Author(s):  
Eric A. Silk ◽  
Jungho Kim ◽  
Ken Kiger
Keyword(s):  
Heat Flux ◽  
Flat Surface ◽  
Spray Cooling ◽  
Technical Conference ◽  
Chamber Pressure ◽  
Working Fluid ◽  
Electronic Systems ◽  
Cross Sectional ◽  
Enhanced Surface ◽  
Trajectory Angle

Experiments were conducted to study the effects of spray trajectory angles on heat flux for flat and enhanced surface spray cooling. The surface enhancement consisted of straight fins machined on the top surface of a copper heater block. Spray cooling curves were obtained with the straight fin surface aligned both parallel (axial) and perpendicular (transverse) to the spray axis. Measurements were also obtained on a flat surface heater block for comparison purposes. Each copper block had a cross-sectional area of 2.0 cm2. A 2×2 nozzle array was used with PF-5060 as the working fluid. Thermal performance data was obtained under nominally degassed (chamber pressure of 41.4 kPa) conditions. Results show that the highest CHF in all cases was attained for a trajectory angle of 30° from the surface normal. Also, straight finned surfaces can enhance critical heat flux (CHF) as much as 75% (heat flux value of 140 W/cm2) relative to the vertical spray orientation for the analogous flat surface case.   This paper was also originally published as part of the Proceedings of the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems.

Study on temperature rise in the screw pair under high frequent oscillation

2016 ◽  
Vol 68 (2) ◽  
pp. 197-205
Author(s):  
Ma Xizhi ◽  
Wang Gang
Keyword(s):  
Heat Flux ◽  
Temperature Field ◽  
Heat Generation ◽  
Temperature Rise ◽  
Axial Direction ◽  
Numerical Results ◽  
Screw Thread ◽  
Content Type ◽  
Frequent Oscillation ◽  
Good Agreement

Purpose – This paper aims to study the mechanism of heat generation in a screw, and investigates the heat flux in the connection screw pair under high frequent oscillation along the axial direction. Heat generated in the screw under high frequent oscillation could be observed in a lot of situations and was significant, and it could cause damage of screw joining and transmission. Design/methodology/approach – A heat flux model in a screw pair under high frequent oscillation along the axial direction is established. Bulk temperature field in the connected parts is calculated by means of finite element methods. A testing device aimed to temperature rise measurement in a thread pair under high frequent oscillation is built. Temperature rises under different operation conditions are measured. Findings – The heat flux generated in the screw pair because of friction between the contact surfaces of the screw thread is obtained. The effects of oscillating amplitude and frequency on heat flux are obtained. It is found that amplitude and frequency have a significant influence on the heat generated under high frequent oscillation. The numerical results show good agreement with the numerical results. Research limitations/implications – This study has some limitations; for example, the friction coefficient and the relative sliding displacement between the thread surfaces need further accurate research. Practical implications – Heat generated in a screw under high frequent oscillation is very rarely mentioned in previous research papers. The methods used in this paper could be used to evaluate the heat flux and temperature under high frequent oscillations. The temperature could be used to calculate the thermal stress and expansion in the screw thread under high frequent oscillation. The screw connections need to be protected from the damage because of heat stress and from getting loose because of heat expansion of the connected parts. Originality/value – The mechanisms of heat generation in the screw pair under high frequent oscillation are studied. The model of heat flux in the screw under high frequency oscillation is established, and it could be used to calculate the heat flux under different operating conditions. The transient temperature field of the connected parts is given. A test facility was built and the experiment to measure the temperatures of the bolt and nut was carried out. The results had good agreement.

Kinetic Model of Adiabatic Temperature Rise of Mass Concrete

2021 ◽  
Vol 13 (5) ◽  
pp. 771-780
Author(s):  
Shou-Kai Chen ◽  
Bo-Wen Xu
Keyword(s):  
Temperature Field ◽  
Temperature Rise ◽  
Initial Conditions ◽  
Dynamic Change ◽  
Adiabatic Temperature ◽  
Model Parameters ◽  
Hydration Reaction ◽  
Mass Concrete ◽  
Adiabatic Temperature Rise ◽  
Proposed Model

The adiabatic temperature rise model of mass concrete is very important for temperature field simulation, same to crack resistance capacity and temperature control of concrete structures. In this research, a thermal kinetics analysis was performed to study the exothermic hydration reaction process of concrete, and an adiabatic temperature rise model was proposed. The proposed model considers influencing factors, including initial temperature, temperature history, activation energy, and the completion degree of adiabatic temperature rise and is theoretically mature and definitive in physical meaning. It was performed on different initial temperatures for adiabatic temperature rise test; the data were employed in a regression analysis of the model parameters and initial conditions. The same function was applied to describe the dynamic change of the adiabatic temperature rise rates for different initial temperatures and different temperature changing processes and subsequently employed in a finite element analysis of the concrete temperature field. The test results indicated that the proposed model adequately fits the data of the adiabatic temperature rise test, which included different initial temperatures, and accurately predicts the changing pattern of adiabatic temperature rise of concrete at different initial temperatures. Compared with the results using the traditional age-based adiabatic temperature rise model, the results of a calculation example revealed that the simulated calculation results using the proposed model can accurately reflect the temperature change pattern of concrete in heat dissipation conditions.

The Temperature Distribution Within a Sphere Placed in a Directed Uniform Heat Flux and Allowed to Radiatively Cool

1985 ◽  
Vol 107 (1) ◽  
pp. 28-32 ◽  
Author(s):  
D. Duffy
Keyword(s):  
Heat Flux ◽  
Temperature Field ◽  
Temperature Distribution ◽  
Analytic Solution ◽  
Blackbody Radiation ◽  
Heat Fluxes ◽  
Uniform Heat Flux ◽  
Transform Methods ◽  
Uniform Heat ◽  
Large Heat

The temperature field within a sphere is found when the sphere is heated by a directed heat flux and cooled by blackbody radiation. For small heat fluxes, the analytic solution is obtained by transform methods. For large heat fluxes, the solution is computed numerically.

scholarly journals Spatiotemporal distribution of the temperature field inside the thin heated foil during impacting liquid spray

2021 ◽  
Vol 2119 (1) ◽  
pp. 012171
Author(s):  
V V Cheverda ◽  
T G Gigola ◽  
P M Somwanshi
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Temperature Field ◽  
Heat Transfer Coefficient ◽  
Infrared Image ◽  
Image Sequence ◽  
Spatiotemporal Distribution ◽  
Average Heat Transfer Coefficient ◽  
Average Heat ◽  
Liquid Spray

Abstract The spatiotemporal distribution of the temperature inside a constantan foil during impacting spray is resolved experimentally in the present work. The received infrared image sequence will be used to find the local and average heat transfer coefficient of the foil. In the future, the results obtained will be used to calculate the heat flux in the region of the contact line of each drop.

scholarly journals A Theorem for Finding Maximum Temperature in Wet Grinding

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
J. L. González-Santander ◽  
G. Martín
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Temperature Field ◽  
Integral Form ◽  
Stationary Regime ◽  
Time Dependent ◽  
Maximum Temperature ◽  
Theoretical Computation ◽  
Constant Heat ◽  
Workpiece Surface

We consider the solutions found in the literature for heat transfer in surface grinding, assuming a constant heat transfer coefficient for the coolant acting on the workpiece surface and a constant or linear heat flux profiles entering into the workpiece. From the integral form of the time-dependent temperature field reached in the workpiece, assuming the previous conditions, we prove that the maximum temperature always occurs in the stationary regime on the workpiece surface within the contact zone between the wheel and the workpiece. This result assures a very rapid method for the theoretical computation of the maximum temperature.

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