scholarly journals Calibration bath uncertainty in precision temperature measurements

2019 ◽  
pp. 9-13
Keyword(s):  
Temperature Gradient ◽  
Measurement Uncertainty ◽  
Temporal Stability ◽  
Temperature Stability ◽  
Bath Temperature ◽  
Temperature Measurements ◽  
Temperature Control System ◽  
Radial Temperature ◽  
Working Volume ◽  
Precision Temperature

Calibration baths are widely used in many laboratories worldwide for the calibration of thermometers by comparison. They come in different shapes and sizes and use different media (water, alcohol, silicon oil etc.), but a certain nonuniformity of theused media is always present. During precision temperature measurements, uniformity (homogeneity and temporal stability) of a calibration bath is of the utmost importance since its contribution to total measurement uncertainty is the largest. The temperature gradient can be described as a change of temperature at different positions inside the bath working volume. Temporal temperature stability depends on many factors such as: the bath temperature, control system, bath construction and the flow of the used media inside the bath, just to name a few. In this paper, we investigate uniformity of a cylindrical calibration bath. Homogeneity is determined by measurement of axial and radial temperature gradient inside the bath. Stability is examined by observation of the change in temperature reading during certain period of time. The obtained results are compared with manufacturer specification and can be used for determination of calibration bath contribution to total measurement uncertainty during calibration of thermometers.

The Effect of Modified Crucible Design and Seed Attachment on SiC Crystal Grown by PVT

2013 ◽  
Vol 740-742 ◽  
pp. 77-80
Author(s):  
Jung Young Jung ◽  
Sang Il Lee ◽  
Mi Seon Park ◽  
Doe Hyung Lee ◽  
Hee Tae Lee ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Temperature Gradient ◽  
Single Crystals ◽  
Crystal Quality ◽  
Full Width ◽  
Half Maximum ◽  
Radial Temperature Gradient ◽  
Radial Temperature ◽  
Better Than

The present research was focused to investigate the effect of internal crucible design that influenced the 4H-SiC crystal growth onto a 6H-SiC seed by PVT method. The crucible design was modified to produce a uniform radial temperature gradient in the growth cell. The seed attachment was also modified with a use of polycrystalline SiC plate. The crystal quality of 4H-SiC single crystals grown in modified crucible and grown with modified seed attachment was revealed to be better than that of crystal grown in conventional crucible. The full width at half maximum (FWHM) values of grown SiC crystals in the conventional crucible, the modified seed attachment and the modified crucible were 285 arcsec, 134 arcsec and 128 arcsec, respectively. The micropipe density (MPD) of grown SiC crystals in the conventional crucible, the modified seed attachment and the modified crucible were 101ea/cm^2, 81ea/cm^2 and 42ea/cm^2, respectively.

Study on the transient temperature distribution of new conical friction plate under sliding friction

2021 ◽  
pp. 095440702110696
Author(s):  
Yanzhong Wang ◽  
Peng Liu
Keyword(s):  
Temperature Distribution ◽  
Temperature Gradient ◽  
Temperature Rise ◽  
Friction Surface ◽  
Sliding Friction ◽  
Conical Surface ◽  
Transient Temperature ◽  
Radial Temperature Gradient ◽  
Radial Temperature ◽  
Friction Plate

Conical friction surface is a novel configuration for friction plate in transmission. Numerical FEA models for transient heat transfer and distribution of conically grooved friction plate have been established to investigate the thermal behavior of the conical surface with different configurations. The finite element method is used to obtain the numerical solution, the temperature test data of conical surface are obtained by the friction test rig. In order to study and compare the temperature behavior of conically grooved friction plate, several three-dimensional transient temperature models are established. The heat generated on the friction interface during the continuous sliding process is calculated. Two different pressure conditions were defined to evaluate the influence of different load conditions on temperature rise and the effects of conical configuration parameters on surface temperature distribution are investigated. The results show that the radial temperature gradient on conical friction surface is obvious. The uniform pressure condition could be used when evaluating the temperature rise of conically grooved friction plate. The increase of the cone height could improve the radial temperature gradient of the conically grooved friction plate.

Destabilization of the Taylor Vortex Flow by a Radial Temperature Gradient

2006 ◽  
Author(s):  
Vale´rie Lepiller ◽  
Jong-Yeon Hwang ◽  
Arnaud Prigent ◽  
Kyung-Soo Yang ◽  
Innocent Mutabazi
Keyword(s):  
Temperature Gradient ◽  
Vortex Flow ◽  
Taylor Vortex ◽  
Radial Temperature Gradient ◽  
Radial Temperature ◽  
Taylor Vortices ◽  
Numerical Studies ◽  
Taylor Vortex Flow ◽  
Spatio Temporal ◽  
Small Inclination

Both experimental and numerical studies have shown that the Taylor vortices are destabilized by a weak radial temperature gradient and transit to spiral vortices with a small inclination. For a large radial temperature gradient, from Taylor vortices emerges a disordered pattern with some windows of spiral vortices. Spatio-temporal characteristics of resulting pattern are presented.

scholarly journals Water Jacket Systems for Temperature Control of Petri Dish Cell Culture Chambers

2019 ◽  
Vol 9 (4) ◽  
pp. 621 ◽  
Author(s):  
Samira Uharek ◽  
Sara Baratchi ◽  
Jiu Zhu ◽  
Majed Alshehri ◽  
Arnan Mitchell ◽  
...  
Keyword(s):  
Cell Culture ◽  
Temperature Gradient ◽  
Transition Period ◽  
Thermal Characteristics ◽  
Petri Dish ◽  
Sample Volume ◽  
Radial Temperature ◽  
Transient Conditions ◽  
Water Jacket ◽  
Stable Conditions

Water jacket systems are routinely used to control the temperature of Petri dish cell culture chambers. Despite their widespread use, the thermal characteristics of such systems have not been fully investigated. In this study, we conducted a comprehensive set of theoretical, numerical and experimental analyses to investigate the thermal characteristics of Petri dish chambers under stable and transient conditions. In particular, we investigated the temperature gradient along the radial axis of the Petri dish under stable conditions, and the transition period under transient conditions. Our studies indicate a radial temperature gradient of 3.3 °C along with a transition period of 27.5 min when increasing the sample temperature from 37 to 45 °C for a standard 35 mm diameter Petri dish. We characterized the temperature gradient and transition period under various operational, geometric, and environmental conditions. Under stable conditions, reducing the diameter of the Petri dish and incorporating a heater underneath the Petri dish can effectively reduce the temperature gradient across the sample. In comparison, under transient conditions, reducing the diameter of the Petri dish, reducing sample volume, and using glass Petri dish chambers can reduce the transition period.

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