scholarly journals Direct and absolute temperature mapping and heat transfer measurements in diode-end-pumped Yb:YAG

2004 ◽  
Vol 79 (2) ◽  
pp. 221-224 ◽  
Author(s):  
S. Chénais ◽  
S. Forget ◽  
F. Druon ◽  
F. Balembois ◽  
P. Georges
Keyword(s):  
Heat Transfer ◽  
Absolute Temperature ◽  
Temperature Mapping

Heat transfer measurements and high resolution absolute temperature mapping in diode-end-pumped Yb:YAG

2004 ◽  
Author(s):  
Sébastien Forget ◽  
Sébastien Chénais ◽  
Frédéric Druon ◽  
François Balembois ◽  
Patrick Georges
Keyword(s):  
Heat Transfer ◽  
High Resolution ◽  
Absolute Temperature ◽  
Temperature Mapping

Mass Transfer Cooling in a Boundary Layer

1961 ◽  
Vol 12 (2) ◽  
pp. 165-188 ◽  
Author(s):  
D. G. Hurley
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Mass Transfer ◽  
Stagnation Point ◽  
Theoretical Work ◽  
Absolute Temperature ◽  
Analogue Computer ◽  
Constant Wall Temperature ◽  
Dimensional Boundary ◽  
Similar Solutions

SummaryPrevious theoretical work on mass transfer cooling is reviewed and it is shown that this may be complemented by similar solutions that occur when the velocity outside a two-dimensional boundary layer varies as some power of the distance from the front stagnation point. The case of stagnation point flow with constant wall temperature is investigated in some detail, under the assumption that the temperature differences are everywhere small compared with the absolute temperature. Calculations on an analogue computer, supplemented by an investigation of the asymptotic behaviour, are used to determine the boundary layer development and heat transfer rates when the coolant is hydrogen, helium, steam or carbon dioxide. It is found that, on a mass flow basis, hydrogen reduces the heat transfer rate most and that steam is the next most effective of the substances investigated.

Effects of a sharp pressure rise on a compressible laminar boundary layer, when the Prandtl number is σ = 0.72

1979 ◽  
Vol 84 (1-2) ◽  
pp. 153-171 ◽  
Author(s):  
N. Curle
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Prandtl Number ◽  
Laminar Boundary Layer ◽  
Pressure Rise ◽  
Adverse Pressure Gradient ◽  
Absolute Temperature ◽  
Stagnation Temperature ◽  
Constant Wall Temperature ◽  
Displacement Thickness

SynopsisFollowing an earlier paper (Curle 1978) we consider a compressible laminar boundary layer with uniform pressure when the distance x along the wall satisfies x < x0 and a prescribed large adverse pressure gradient when x > x0. The viscosity and absolute temperature are again taken to be proportional, but the Prandtl number is no longer assumed to be unity. After applying the Illingworth-Stewartson transformation, the transformed external velocity u1(x) is chosen so thatis large and constant, where Ts is the stagnation temperature, Tw is the (constant) Wall temperature and u0 is the upstream value of u1(x).The flow reacts to this sharp pressure rise mainly in a thin inner sublayer, so inner and outer asymptotic expansions are derived and matched for functions F and S which determine the stream function and the temperature.The skin friction, heat transfer, displacement thickness and momentum thickness are determined as functions of , andinvolve two parameters B1, B2, which depend upon the Mach number and the walltemperature. Detailed numerical calculations are presented here for σ = 0.72. In particular, it is seen that the heat transfer rate varies roughly like σ⅓ except near to separation, where it varies like σ¼.

The Influences of Property Variations on Natural Convection from Vertical Surfaces

1981 ◽  
Vol 103 (4) ◽  
pp. 609-612 ◽  
Author(s):  
A. M. Clausing ◽  
S. N. Kempka
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Ambient Temperature ◽  
Radiative Heat ◽  
Heated Surface ◽  
Convection Heat Transfer ◽  
Absolute Temperature ◽  
Turbulent Regime ◽  
Transfer Rates ◽  
Rayleigh Numbers

The objective of this paper is to show the influences of property variations in natural convection. Heat transfer from a vertical isothermal, heated surface to gaseous nitrogen is experimentally investigated. The ambient temperature, T∞, is varied in order to cover a large range of the Rayleigh number and also to enable the generation of large values of this parameter. The range 80 K < T∞ < 320 K results in Rayleigh numbers between 107 and 2 × 1010 for the 0.28 m model. By using a cryogenic environment, large ratios of the absolute temperature of the wall to the ambient temperature, Tw/T∞, are generated without the results being masked by radiative heat transfer. The range 1 < Tw/T∞ < 2.6 is investigated. Variable properties cause dramatic increases in heat transfer rates in the turbulent regime, and virtually no influence is seen in the laminar regime. The results obtained correlate extremely well with the addition of a single parameter Tw/T∞.

scholarly journals Temperature-Change-Based Thermal Tomography

2009 ◽  
Vol 2009 ◽  
pp. 1-4 ◽  
Author(s):  
Yong Xu ◽  
Xiangyu Wei ◽  
Ge Wang
Keyword(s):  
Temperature Change ◽  
Critical Role ◽  
Biological Tissues ◽  
Absolute Temperature ◽  
Relative Temperature ◽  
Temperature Mapping ◽  
Thermal Therapies ◽  
Thermal Tomography ◽  
Breast Phantom ◽  
Magnetic Resonance Imaging Mri

Thermal properties of biological tissues play a critical role in the study of tumor angiogenesis and the design and monitoring of thermal therapies. To map thermal parameters noninvasively, we propose temperature-change-based thermal tomography (TTT) that relies on relative temperature mapping using magnetic resonance imaging (MRI). Our approach is unique in two aspects: (1) the steady-state body temperature in thermal equilibrium is not restricted to be spatially invariant, and (2) absolute temperature mapping is not required. These two features are physiologically realistic and technically convenient. Our numerical simulation indicates that a(9 mm)3tumor inside a breast phantom can be reliably depicted, assuming moderate temperature mapping accuracy of0.5∘C.

Infrared Lock-In Thermography: From Localization of Low Power and Masked Defects to Absolute Temperature Mapping for Product Debug

2019 ◽  
Author(s):  
J. Jalink ◽  
A. Firiti ◽  
J. van den Biggelaar ◽  
A. Reverdy ◽  
B. Lai
Keyword(s):  
Low Power ◽  
Silicon Oxide ◽  
Optical Resolution ◽  
Absolute Temperature ◽  
Fault Isolation ◽  
Ultra Low Power ◽  
Temperature Mapping ◽  
Low Power Dissipation ◽  
Lock In ◽  
Level Analysis

Abstract The application of IR-Lock-In Thermography (IRLIT) has been extended from 2D and 3D package fault isolation to on-die level analysis. In addition, the technique has become more sensitive allowing for detection of much lower dissipated power. In this paper, several fault localization cases covering PCB assemblies down to die level analysis are discussed using IR-LIT and absolute temperature mapping. Where possible, the analysis is complemented with physical defect verification. The fault isolation cases include an ultra-low power dissipation (&lt;150 nW) and several case studies with high ohmic connections. For the latter a new method based on phase mapping is discussed allowing for 2D localization of thermally invisible defects. The method will be demonstrated on a test vehicle where phase data extracted from a visible feature of the device under test is studied. After this, a case study at die level is presented in an attempt to distinguish the phase information from two stacked M2-M3 metallization layers of the Back-End Of the Line (BEOL). Finally, temperature mapping results of a 5 micron wide aluminum feature in silicon-oxide is presented that is pushing the optical resolution of the tool.

Some Aspects of Laminar Boundary Layer Separation in Compressible Flow with no Heat Transfer to the Wall

1953 ◽  
Vol 4 (2) ◽  
pp. 123-150 ◽  
Author(s):  
G. E. Gadd
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Prandtl Number ◽  
Pressure Distribution ◽  
Compressible Flow ◽  
Laminar Boundary Layer ◽  
Free Stream ◽  
Boundary Layer Separation ◽  
Absolute Temperature ◽  
Laminar Separation

SummaryAn analysis has been made which suggests that, with the types of pressure distribution most usual in practice and free stream Mach numbers up to 10, no serious errors would be introduced into the calculation of the laminar separation point by the assumption that σ, the Prandtl number, and ω, the index of variation of viscosity with absolute temperature, are equal to unity. (Typical actual values of σ and ω for air are 0.72 and 0.89 respectively).

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