Effect of Gas Flow on the Temperature Rise of a Micro-Beam-Type Thermal Conductivity Detector

2013 ◽  
Author(s):  
Hiroshi Takamatsu ◽  
Kosuke Hisada ◽  
Takanobu Fukunaga ◽  
Kosaku Kurata
Keyword(s):  
Thermal Conductivity ◽  
Temperature Rise ◽  
Gas Flow ◽  
Heat Dissipation ◽  
Air Flow ◽  
Leading Edge ◽  
Potential Core ◽  
Mems Sensor ◽  
Beam Type ◽  
Dc Current

We have proposed a “micro-beam” MEMS sensor for measuring the thermal conductivity of gases and liquids. It is a beam-shaped metallic foil sensor, approximately 10 μm in length, that is built over a trench on a silicon substrate. The principle of the measurement is to determine the thermal conductivity of a sample from the temperature rise of the sensor at a steady state, which is achieved within a millisecond. Potential application of the sensor would be gas sensors and gas chromatography, where the sensor is exposed to a gas flow. Hence the objective of the present study is to examine the effect of flow on the temperature of the sensor. A chip with a platinum sensor fabricated on its surface was embedded in a flat PVC plate and placed in the potential core of an air flow from a nozzle. The electrical resistance of the sensor was measured by a four-wire technique with heating the sensor with DC current. The results showed that the temperature rise at a given heating rate, which indicates the heat dissipating potential to the air, did not change with increasing the air velocity. It also agreed well each other irrespective of the angle of attack or the length from the leading edge. The results demonstrated that the temperature rise of the sensor was independent of the air flow, suggesting that the heat dissipation was governed only by the heat conduction to the air.

B124 Micro-Beam-Type Thermal Conductivity Detector : Effect of Flow on the Temperature Rise of the Sensor

2012 ◽  
Vol 2012 (0) ◽  
pp. 49-50
Author(s):  
Kosuke Hisada ◽  
Takanobu Fukunaga ◽  
Satoru Uchida ◽  
Kosaku Kurata ◽  
Hiroshi Takamatsu
Keyword(s):  
Thermal Conductivity ◽  
Temperature Rise ◽  
Thermal Conductivity Detector ◽  
Beam Type ◽  
Detector Effect

scholarly journals Heat Dissipation and Ripple Current Rating in Electrolytic Capacitors

1975 ◽  
Vol 2 (2) ◽  
pp. 109-114 ◽  
Author(s):  
F. G. Hayatee
Keyword(s):  
Thermal Conductivity ◽  
Heat Flow ◽  
Temperature Rise ◽  
Mathematical Analysis ◽  
Heat Dissipation ◽  
Thermal Characteristics ◽  
Electrolytic Capacitors ◽  
Allowable Temperature

The ripple current rating in electrolytic capacitors is limited by the maximum allowable temperature rise inside the capacitor. The temperature rise is determined by the I2R losses inside the capacitor and the efficiency of heat flow from the interior to the surrounding. The ripple current rating can be extended by either reducing the tanδof the capacitor or by increasing the efficiency of heat flow to ambient.The heat flow is determined by the thermal characteristics of the capacitor surface and thermal conductivity of the medium separating the capacitor winding from the surrounding.In this article a mathematical analysis for the heat flow in capacitors is given. The effects of various parameters are examined and methods of extending the ripple current rating are discussed.

Thermal Spreading Performance of Copper-Graphite Film Attached on BLM-Reflector

2014 ◽  
Vol 540 ◽  
pp. 126-129
Author(s):  
Chi Chiang Lee ◽  
Hong Te Hsu ◽  
Ming Chih Huang ◽  
Hong Hsin Huang
Keyword(s):  
Thermal Conductivity ◽  
Temperature Rise ◽  
Temperature Increase ◽  
Heat Dissipation ◽  
Thermal Spread ◽  
Graphite Film ◽  
Performance Results

In LEDs Backlight Module, reflector who made by metal and contacts to LEDs possesses higher thermal conductivity. The reflector was expected to dissipate the heat from the LEDs, however, it is not good enough to decrease the LEDs temperature rise. In this study, a copper-graphite film with thickness of 82.5 μm was attached to the back of reflector to increase the heat dissipation. The temperatures along the x, y, and z direction were measured to evaluate the thermal spread performance. Results showed that a 19% temperature rise decrease was found for LEDs and a half temperature increase was also measured along the LEDs bar direction. In addition to that a higher thermal conductivity could spread the heat to the remote end resulting in temperature increasing to enhance the heat dissipation by way of reflector.

scholarly journals Experimental study on the factors affecting torque of beam-type implant torque wrenches

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Hiroki Shiba ◽  
Yuji Sato ◽  
Junichi Furuya ◽  
Tokiko Osawa ◽  
Akio Isobe ◽  
...  
Keyword(s):  
Coefficient Of Variation ◽  
Leading Edge ◽  
Beam Width ◽  
Factors Affecting ◽  
Tightening Force ◽  
Torque Wrench ◽  
Screw Breakage ◽  
Beam Type ◽  
Accuracy And Repeatability ◽  
Excellent Accuracy

Abstract Background Screw breakage and loosening are the most common mechanical complications associated with implant treatment, and they may occur due to excess or inadequate screw tightening torque. When fastening and fixing the implant superstructure, screws are tightened using a torque wrench, which is essential for an accurate tightening force. However, the characteristics of the torque wrench have not been fully verified. Therefore, we aimed to clarify the factors affecting the torque with a focus on beam-type torque wrenches, which are the main types of wrenches. Methods The torque values generated by beam-type torque wrenches from eight manufacturers were measured using a torque gauge. To investigate the influence of the location of the beam relative to the scale, measurements were performed with a scale aligned with the trailing edge, center, and leading edge of the beam respectively. Additionally, measurements were taken at 90°, 60°, and 30° to examine the effect of the angle at which the examiner read the torque value. Under each condition, a single examiner applied the recommended torque to each manufacturer's screws five times in a clockwise direction. The average measured torque, standard deviation, bias, and coefficient of variation were calculated and compared accordingly. Results Wrenches from six manufacturers demonstrated excellent accuracy for measurements at the center of the beam (bias within ± 4%). For measurements at 90°, equipments from five manufacturers displayed excellent accuracy (bias within ± 7%), and seven showed excellent repeatability (coefficient of variation ≤ 2%). Conclusion The scale should be aligned with the center of the beam and read from 90° while using a torque wrench. The accuracy and repeatability torques generated by the wrenches differed according to the manufacturer, scale width, scale line width, beam width, and distance between the scale and beam center. Based on these results, we suggest that a torque wrench must be selected after determining the difference in the structure of the torque wrench.

scholarly journals Estimations on Properties of Redox Reactions to Electrical Energy and Storage Device of Thermoelectric Pipe (TEP) Using Polymeric Nanofluids

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1812
Author(s):  
Qin Gang ◽  
Rong-Tsu Wang ◽  
Jung-Chang Wang
Keyword(s):  
Thermal Conductivity ◽  
Power Density ◽  
Heat Dissipation ◽  
Electrical Energy ◽  
Steel Tube ◽  
Storage Device ◽  
Stainless Steel Tube ◽  
The Novel ◽  
Empirical Formulas ◽  
Dissipative Heat

A thermoelectric pipe (TEP) is constructed by tubular graphite electrodes, Teflon material, and stainless-steel tube containing polymeric nanofluids as electrolytes in this study. Heat dissipation and power generation (generating capacity) are both fulfilled with temperature difference via the thermal-electrochemistry and redox reaction effects of polymeric nanofluids. The notion of TEP is to recover the dissipative heat from the heat capacity generated by the relevant machine systems. The thermal conductivity and power density empirical formulas of the novel TEP were derived through the intelligent dimensional analysis with thermoelectric experiments and evaluated at temperatures between 25 and 100 °C and vacuum pressures between 400 and 760 torr. The results revealed that the polymeric nanofluids composed of titanium dioxide (TiO2) nanoparticles with 0.2 wt.% sodium hydroxide (NaOH) of the novel TEP have the best thermoelectric performance among these electrolytes, including TiO2 nanofluid, TiO2 nanofluid with 0.2 wt.% NaOH, deionized water, and seawater. Furthermore, the thermal conductivity and power density of the novel TEP are 203.1 W/(m·K) and 21.16 W/m3, respectively.

scholarly journals Study of Thermometry in Two-Dimensional Sb2Te3 from Temperature-Dependent Raman Spectroscopy

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Manavendra P. Singh ◽  
Manab Mandal ◽  
K. Sethupathi ◽  
M. S. Ramachandra Rao ◽  
Pramoda K. Nayak
Keyword(s):  
Thermal Conductivity ◽  
Raman Spectroscopy ◽  
Temperature Coefficient ◽  
Heat Dissipation ◽  
Peak Position ◽  
Two Dimensional ◽  
Phonon Modes ◽  
Temperature Dependent ◽  
Excellent Candidate ◽  
High Figure

AbstractDiscovery of two-dimensional (2D) topological insulators (TIs) demonstrates tremendous potential in the field of thermoelectric since the last decade. Here, we have synthesized 2D TI, Sb2Te3 of various thicknesses in the range 65–400 nm using mechanical exfoliation and studied temperature coefficient in the range 100–300 K using micro-Raman spectroscopy. The temperature dependence of the peak position and line width of phonon modes have been analyzed to determine the temperature coefficient, which is found to be in the order of 10–2 cm−1/K, and it decreases with a decrease in Sb2Te3 thickness. Such low-temperature coefficient would favor to achieve a high figure of merit (ZT) and pave the way to use this material as an excellent candidate for thermoelectric materials. We have estimated the thermal conductivity of Sb2Te3 flake with the thickness of 115 nm supported on 300-nm SiO2/Si substrate which is found to be ~ 10 W/m–K. The slightly higher thermal conductivity value suggests that the supporting substrate significantly affects the heat dissipation of the Sb2Te3 flake.

Influence of Anisotropic Thermal Conductivity on Overall Cooling Effectiveness on a Film Cooled Leading Edge

2021 ◽  
pp. 1-22
Author(s):  
Carol Bryant ◽  
James L. Rutledge
Keyword(s):  
Thermal Conductivity ◽  
Temperature Distribution ◽  
Film Cooling ◽  
Leading Edge ◽  
Ceramic Matrix Composites ◽  
Internal Cooling ◽  
Matrix Composites ◽  
Edge Region ◽  
Turbine Engine ◽  
Anisotropic Thermal Conductivity

Abstract Increasing interest in the use of ceramic matrix composites (CMCs) for gas turbine engine hot gas path components requires a thorough examination of the thermal behavior one may expect of such components. Their highly anisotropic thermal conductivity is a substantial departure from traditional metallic components and can influence the temperature distribution in surprising ways. With the ultimate surface temperature dependent upon the internal cooling scheme, including cooling from within the film cooling holes themselves, as well as the external film cooling, the relative influence of these contributions to cooling can be affected by the directionality of the thermal conductivity. Conjugate heat transfer computational simulations were performed to evaluate the effect of anisotropy in the leading edge region of a turbine component. The leading edge region is modeled as a fully film-cooled half cylinder with a flat afterbody. The anisotropic directionality of the thermal conductivity is shown to have a significant effect on the temperature distribution over the surface of the leading edge. While structural considerations with CMC components are often paramount, designers should be aware of the thermal ramifications associated with the selection of the CMC layup.

TRIGGERING OF DETONATION PROCESSES IN PROPULSION CHAMBER

2021 ◽  
Vol 14 (2) ◽  
pp. 40-45
Author(s):  
D. V. VORONIN ◽  
Keyword(s):  
Thermal Conductivity ◽  
Numerical Modeling ◽  
Gas Flow ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Navier Stokes Equations ◽  
Chemically Reacting ◽  
Plane Disk ◽  
And Diffusion

The Navier-Stokes equations have been used for numerical modeling of chemically reacting gas flow in the propulsion chamber. The chamber represents an axially symmetrical plane disk. Fuel and oxidant were fed into the chamber separately at some angle to the inflow surface and not parallel one to another to ensure better mixing of species. The model is based on conservation laws of mass, momentum, and energy for nonsteady two-dimensional compressible gas flow in the case of axial symmetry. The processes of viscosity, thermal conductivity, turbulence, and diffusion of species have been taken into account. The possibility of detonation mode of combustion of the mixture in the chamber was numerically demonstrated. The detonation triggering depends on the values of angles between fuel and oxidizer jets. This type of the propulsion chamber is effective because of the absence of stagnation zones and good mixing of species before burning.

Study on Effective Radial Thermal Conductivity of Gas Flow through a Methanol Reactor

2015 ◽  
Vol 13 (1) ◽  
pp. 103-112 ◽  
Author(s):  
Kun Lei ◽  
Hongfang Ma ◽  
Haitao Zhang ◽  
Weiyong Ying ◽  
Dingye Fang
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Reynolds Number ◽  
Temperature Distribution ◽  
Large Scale ◽  
Gas Flow ◽  
Fixed Bed ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Particle Reynolds Number

Abstract The heat conduction performance of the methanol synthesis reactor is significant for the development of large-scale methanol production. The present work has measured the temperature distribution in the fixed bed at air volumetric flow rate 2.4–7 m3 · h−1, inlet air temperature 160–200°C and heating tube temperature 210–270°C. The effective radial thermal conductivity and effective wall heat transfer coefficient were derived based on the steady-state measurements and the two-dimensional heat transfer model. A correlation was proposed based on the experimental data, which related well the Nusselt number and the effective radial thermal conductivity to the particle Reynolds number ranging from 59.2 to 175.8. The heat transfer model combined with the correlation was used to calculate the temperature profiles. A comparison with the predicated temperature and the measurements was illustrated and the results showed that the predication agreed very well with the experimental results. All the absolute values of the relative errors were less than 10%, and the model was verified by experiments. Comparing the correlations of both this work with previously published showed that there are considerable discrepancies among them due to different experimental conditions. The influence of the particle Reynolds number on the temperature distribution inside the bed was also discussed and it was shown that improving particle Reynolds number contributed to enhance heat transfer in the fixed bed.

Orientation Specific Thermal Properties of Polyimide Film

2000 ◽  
Vol 123 (3) ◽  
pp. 273-277 ◽  
Author(s):  
Robert J. Samuels ◽  
Nancy E. Mathis
Keyword(s):  
Thermal Conductivity ◽  
Heat Dissipation ◽  
Polyimide Film ◽  
New Materials ◽  
Polyimide Films ◽  
Nondestructive Technique ◽  
Theoretical Understanding ◽  
First Time ◽  
The Relationship ◽  
Transfer Mechanisms

The present study examines the relationship between thermal conductivity and planarity in polyimide films. The samples tested were specially prepared to range in orientation from three dimensionally random to highly planar. The molecular structure and orientation of the polyimide film have been characterized by polarizing microscope techniques, while the thermal conductivity measurements were done using a new rapid nondestructive technique. This correlation represents the first time thermal conductivity has been measured by modified hot wire techniques and related to the internal structure of polyimide. This work contributes to a deeper theoretical understanding of thermal conductivity and heat transfer mechanisms as they relate to orientation. Thermal conductivity evaluation could provide a new tool in the arsenal of structural characterization techniques. This relationship between thermal conductivity and orientation is key for applications of directional heat dissipation in the passive layers of chip assemblies. Such a correlation has potential to speed the development cycles of new materials during formulation as well as assure properties during production.

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