On microscale heat transfer in thin film pyroelectric sensors

2002 ◽  
Author(s):  
S. Srinivasan ◽  
E. Marotta ◽  
J. Ochterbeck ◽  
R. Schwartz ◽  
R. Miller
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Microscale Heat Transfer ◽  
Pyroelectric Sensors

Effects of Rotation on Blade Surface Heat Transfer: An Experimental Investigation

1997 ◽  
Author(s):  
Roger W. Moss ◽  
Roger W. Ainsworth ◽  
Tom Garside
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Experimental Investigation ◽  
Turbine Blade ◽  
Time History ◽  
Surface Heat ◽  
Blade Surface ◽  
Surface Heat Transfer ◽  
Effects Of Rotation ◽  
Wake Passing

Measurements of turbine blade surface heat transfer in a transient rotor facility are compared with predictions and equivalent cascade data. The rotating measurements involved both forwards and reverse rotation (wake free) experiments. The use of thin-film gauges in the Oxford Rotor Facility provides both time-mean heat transfer levels and the unsteady time history. The time-mean level is not significantly affected by turbulence in the wake; this contrasts with the cascade response to freestream turbulence and simulated wake passing. Heat transfer predictions show the extent to which such phenomena are successfully modelled by a time-steady code. The accurate prediction of transition is seen to be crucial if useful predictions are to be obtained.

Thin-film thermocouples for localized heat transfer measurements

10.2514/3.836 ◽  
1996 ◽  
Vol 10 (4) ◽  
pp. 607-612 ◽  
Author(s):  
J. Lepicovsky ◽  
R. J. Bruckner ◽  
F. A. Smith
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Thin Film Thermocouples

Theoretical Analysis of Thin Film Evaporation in the Wicks of Loop Heat Pipes

2021 ◽  
pp. 1-14
Author(s):  
Bingyao Lin ◽  
Nanxi Li ◽  
Shiyue Wang ◽  
Leren Tao ◽  
Guangming Xu ◽  
...  
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Pore Size ◽  
Momentum Conservation ◽  
Loop Heat Pipes ◽  
Thin Film Evaporation ◽  
Film Evaporation ◽  
Quantity Of Heat

Abstract In this paper, a thin film evaporation model that includes expressions for energy, mass and momentum conservation was established through the augmented Young-Laplace model. Based on this model, the effects of pore size and superheating on heat transfer during thin film evaporation were analyzed. The influence of the wick diameter of the loop heat pipe (LHP) on the critical heat flux of the evaporator is analyzed theoretically. The results show that pore size and superheating mainly influence evaporation through changes in the length of the transition film and intrinsic meniscus. The contribution of the transition film area is mainly reflected in the heat transfer coefficient, and the contribution of the intrinsic meniscus area is mainly apparent in the quantity of heat that is transferred. When an LHP evaporator is operating in a state of surface evaporation, a higher heat transfer coefficient can be achieved using a smaller pore size.

Submerged Jet Impingement Cooling of a Nanostructured Plate

2010 ◽  
Author(s):  
Muhsincan Sesen ◽  
Ali Kosar ◽  
Ebru Demir ◽  
Evrim Kurtoglu ◽  
Nazli Kaplan ◽  
...  
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Heat Flux ◽  
Silicon Wafer ◽  
Heat Removal ◽  
Jet Impingement ◽  
Wafer Surface ◽  
Small Scale ◽  
Copper Thin Film ◽  
Thin Film Layer

In this paper, the results of a series of heat transfer experiments conducted on a compact electronics cooling device based on single phase jet impingement techniques are reported. Deionized-water is propelled into four microchannels of inner diameter 685 μm which are used as nozzles and located at a nozzle to surface distance of 2.5mm. The generated jet impingement is targeted through these channels towards the surface of a nanostructured plate. This plate of size 20mmx20mm consisted of ∼600 nm long copper nanorod arrays with an average nanorod diameter of ∼150 nm, which were integrated on top of a silicon wafer substrate coated with a copper thin film layer (i.e. Cu-nanorod/Cu-film/Silicon-wafer). Heat removal characteristics induced through jet impingement are investigated using the nanostructured plate and compared to results obtained from a flat plate of copper thin film coated on silicon wafer surface. Enhancement in heat transfer up to 15% using the nanostructured plate has been reported in this paper. Heat generated by small scale electronic devices is simulated using a thin film heater placed on an aluminum base. Surface temperatures are recorded by a data acquisition system with the thermocouples integrated on the surface at various locations. Constant heat flux provided by the film heater is delivered to the nanostructured plate placed on top of the base. Volumetric flow rate and heat flux values were varied in order to better characterize the potential enhancement in heat transfer by nanostructured surfaces.

Research on Heat Transfer Performance of Water Film for Outside the Tubes of the Microscale Evaporative Condenser

2009 ◽  
Author(s):  
Minghui Hu ◽  
Dongsheng Zhu ◽  
Jialong Shen
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Transfer Performance ◽  
Water Film ◽  
Transfer Performance ◽  
Air Velocity ◽  
Microscale Heat Transfer ◽  
High Heat Transfer ◽  
Spray Density

It is requested to develop a microscale and high performance heat exchanger for small size energy equipments. The heat transfer performance of the water film on the condensing coils of the microscale evaporative condenser was studied for a single-stage compressed refrigeration cycle system. Under various operation conditions, the effects of the spray density and the head-on air velocity on the heat transfer performance of the water film were investigated. The results show that the microscale heat transfer coefficient of the water film αw increases with the increase of spray density and decreases with the increase of head-on air velocity. The results indicate that the key factor affecting the microscale heat transfer of the water film is the spray density. As the results, it is measured that the present device attained high heat transfer quantity despite the weight is light. In addition, via regression analysis of the experimental data, the correlation equation for calculating the microscale heat transfer coefficient of the water film was obtained, its regression correlation coefficient R is 0.98 and the standard deviation is 7.5%. Finally, the correlations from other works were compared. The results presented that the experimental correlation had better consistency with the correlations from other works. In general, the obtained experimental results of the water film heat transfer are helpful to the design and practical operation of the microscale evaporative condensers.

scholarly journals Capillary-Limited Evaporation From Well-Defined Microstructured Surfaces

2013 ◽  
Author(s):  
Solomon Adera ◽  
Rishi Raj ◽  
Evelyn N. Wang
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Heat Flux ◽  
Phase Change ◽  
Thermal Management ◽  
Latent Heat ◽  
Thin Film Evaporation ◽  
Film Evaporation ◽  
Microstructured Surfaces ◽  
Latent Heat Of Vaporization

Thermal management is increasingly becoming a bottleneck for a variety of high power density applications such as integrated circuits, solar cells, microprocessors, and energy conversion devices. The performance and reliability of these devices are usually limited by the rate at which heat can be removed from the device footprint, which averages well above 100 W/cm2 (locally this heat flux can exceed 1000 W/cm2). State-of-the-art air cooling strategies which utilize the sensible heat are insufficient at these large heat fluxes. As a result, novel thermal management solutions such as via thin-film evaporation that utilize the latent heat of vaporization of a fluid are needed. The high latent heat of vaporization associated with typical liquid-vapor phase change phenomena allows significant heat transfer with small temperature rise. In this work, we demonstrate a promising thermal management approach where square arrays of cylindrical micropillar arrays are used for thin-film evaporation. The microstructures control the liquid film thickness and the associated thermal resistance in addition to maintaining a continuous liquid supply via the capillary pumping mechanism. When the capillary-induced liquid supply mechanism cannot deliver sufficient liquid for phase change heat transfer, the critical heat flux is reached and dryout occurs. This capillary limitation on thin-film evaporation was experimentally investigated by fabricating well-defined silicon micropillar arrays using standard contact photolithography and deep reactive ion etching. A thin film resistive heater and thermal sensors were integrated on the back side of the test sample using e-beam evaporation and acetone lift-off. The experiments were carried out in a controlled environmental chamber maintained at the water saturation pressure of ≈3.5 kPa and ≈25 °C. We demonstrated significantly higher heat dissipation capability in excess of 100 W/cm2. These preliminary results suggest the potential of thin-film evaporation from microstructured surfaces for advanced thermal management applications.

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