High-Temperature Thermocouple and Heat Flux Gauge Using a Unique Thin Film-Hardware Hot Junction

1985 ◽  
Vol 107 (4) ◽  
pp. 938-944 ◽  
Author(s):  
C. H. Liebert ◽  
R. Holanda ◽  
S. A. Hippensteele ◽  
C. A. Andracchio
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Flux ◽  
High Temperature ◽  
High Heat ◽  
High Heat Flux ◽  
Transfer Experiment ◽  
Plate Heat ◽  
Good Agreement

A special thin film-hardware material thermocouple (TC) and heat flux gauge concept for a reasonably high-temperature and high heat flux, flat-plate heat transfer experiment was fabricated and tested to gauge temperatures of 911 K. This unique concept was developed for minimal disturbance of boundary layer temperature and flow over the plates and minimal disturbance of heat flux through the plates. Comparison of special heat flux gauge Stanton number output at steady-state conditions with benchmark literature data was good and agreement was within a calculated uncertainty of the measurement system. Also, good agreement of special TC and standard TC outputs was obtained and the results are encouraging. Oxidation of thin film thermoelements was a primary failure mode after about 5 hr of operation.

Numerical Modeling of Chevron Plate Heat Exchangers for Thermal Management Applications

2016 ◽  
Author(s):  
Harsh Tamakuwala ◽  
Ryan Von Ness ◽  
Debjyoti Banerjee
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
High Heat ◽  
Plate Heat Exchanger ◽  
High Heat Flux ◽  
Plate Heat ◽  
Geometric Conditions ◽  
Swirl Flows

Plate-fin heat exchangers are widely used in industries especially aerospace, cryogenics, food and chemical process industries where high heat flux surface area per unit volume is of prime importance. These heat exchangers consists of series of corrugated plates (herringbone or chevron), separated by gasket sealing. Chevron angled plates are one of the most commonly used type of geometry. The complex design of chevron plate heat exchanger, induces high turbulence and flow reversals causing high heat transfer through the plates. This paper discusses about the computational fluid dynamics simulations conducted over a simplified geometry of Chevron Plate Heat Exchanger to understand the formulation of vortices at different Reynold’s number for various aspect ratios. A single phase laminar flow with periodic boundary condition is used for analysis of the fluid behavior in a unit pattern of the corrugation geometry. Based on different flow and geometric conditions, varying amounts of swirl-flows are observed and different behavior of shear stress and heat transfer plot along the length of the plate is observed. At higher Reynolds numbers (Re), the re-circulations and mixing by the induced vortices causes significant rise of heat flux, with marginal increase in friction factor.

Heat Transfer and Hydraulic Characteristics of Cooling Water in a Flat Plate Heat Sink for High Heat Flux IGBT

2016 ◽  
Author(s):  
Chang-Nian Chen ◽  
Ji-Tian Han ◽  
Wei-Ping Gong ◽  
Tien-Chien Jen
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Flat Plate ◽  
Heat Sink ◽  
High Heat ◽  
Heat Fluxes ◽  
High Heat Flux ◽  
Hydraulic Characteristics ◽  
Flow Rates ◽  
Plate Heat

High heat flux is very dangerous for electronic heat transfer, such as IGBT (Insulated Gate Bipolar Transistor) cooling. In order to explore and master the heat transfer and hydraulic characteristics for IGBT cooling, experiments have been carried out to study the situation mentioned above in a flat plate heat sink, which was designed for high heat flux IGBT cooling. The geometrical parameters of the test section are as follows: outline dimension 229 mm × 124 mm × 30 mm; flow channels of 229 mm × 3 mm × 4 mm in total of 20. The experiments performed at atmospheric pressure and with inlet temperatures of 25–35°C, heat fluxes of 3.5–18.9 kW/m2. The influence of temperatures, heat fluxes on IGBT surface temperature and the cooling effect of the liquid cold plate have been investigated under a range of flow rates of 280–2300 kg/m2s. It was found that the heat transfer enhancement was very obvious using this kind of small sized channel for IGBT cooling, which was tens of times of the effect than air cooling or triple of the effect than that in normal sized channels. And the heat transfer enhancement increases with increasing heat fluxes and flow rates, while it decreases with increasing inlet temperatures. Most of the experimental results show good cooling effect as expected. However, it is dangerous for the cooling system under high heat fluxes when the system starts or stops suddenly, when the Respond Time (RT) is less than 5 seconds to cut off heated power. Also, the cooling performance is bad when the heat fluxes increased greatly, which is considered as abnormal situation in operating. The effect on IGBT surface temperature of heat flux is more obvious when the average Nusselt Number is smaller. For hydraulic characteristics observed, it was found that the flow friction increased with flow rates increasing, but the pressure drops of heated flow channels ahead were slightly larger than those back, especially under large flow rates conditions. That is because the temperatures of flow heated in channels ahead are lower than those back, which causes the fluid viscosity to be higher. At last, this paper suggested a series of method for enhancing heat transfer in flat plate heat sink, and also gave some ways to avoid heat transfer dangerous situations for IGBT cooling, which can provide a basis for thermodynamic and hydraulic calculation of flat plate heat sink design and lectotype.

Heat Transfer in a Surfactant Drag-Reducing Solution—A Comparison With Predictions for Laminar Flow

2005 ◽  
Vol 128 (6) ◽  
pp. 557-563 ◽  
Author(s):  
Paul L. Sears ◽  
Libing Yang
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Reynolds Numbers ◽  
High Heat ◽  
High Heat Flux ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Nusselt Numbers ◽  
Drag Reducing Additive ◽  
Good Agreement

Heat transfer coefficients were measured for a solution of surfactant drag-reducing additive in the entrance region of a uniformly heated horizontal cylindrical pipe with Reynolds numbers from 25,000 to 140,000 and temperatures from 30to70°C. In the absence of circumferential buoyancy effects, the measured Nusselt numbers were found to be in good agreement with theoretical results for laminar flow. Buoyancy effects, manifested as substantially higher Nusselt numbers, were seen in experiments carried out at high heat flux.

Experimental Study on Heat Transfer Augmentation for High Heat Flux Removal in Rib-Roughened Narrow Channels

1998 ◽  
Vol 35 (9) ◽  
pp. 671-678 ◽  
Author(s):  
Md. Shafiqul ISLAM ◽  
Ryutaro HINO ◽  
Katsuhiro HAGA ◽  
Masanori MONDE ◽  
Yukio SUDO
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Flux ◽  
High Heat ◽  
High Heat Flux ◽  
Narrow Channels ◽  
Heat Transfer Augmentation ◽  
Rib Roughened

Development of Cooling System for a Large Area at High Heat Flux by Using Flow Boiling in Narrow Channels

2009 ◽  
Author(s):  
Shinichi Miura ◽  
Yukihiro Inada ◽  
Yasuhisa Shinmoto ◽  
Haruhiko Ohta
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Flow Rate ◽  
Mass Velocity ◽  
Cooling System ◽  
Volumetric Flow Rate ◽  
High Heat ◽  
High Heat Flux ◽  
Gap Size ◽  
Heated Channel

Advance of an electronic technology has caused the increase of heat generation density for semiconductors densely integrated. Thermal management becomes more important, and a cooling system for high heat flux is required. It is extremely effective to such a demand using flow boiling heat transfer because of its high heat removal ability. To develop the cooling system for a large area at high heat flux, the cold plate structure of narrow channels with auxiliary unheated channel for additional liquid supply was devised and confirmed its validity by experiments. A large surface of 150mm in heated length and 30mm in width with grooves of an apex angle of 90 deg, 0.5mm depth and 1mm in pitch was employed. A structure of narrow rectangular heated channel between parallel plates with an unheated auxiliary channel was employed and the heat transfer characteristics were examined by using water for different combinations of gap sizes and volumetric flow rates. Five different liquid distribution modes were tested and their data were compared. The values of CHF larger than 1.9×106W/m2 for gap size of 2mm under mass velocity based on total volumetric flow rate and on the cross section area of main heated channel 720kg/m2s or 1.7×106W/m2 for gap size of 5mm under 290kg/m2s were obtained under total volumetric flow rate 4.5×10−5m3/s regardless of the liquid distribution modes. Under several conditions, the extensions of dry-patches were observed at the upstream location of the main heated channel resulting burnout not at the downstream but at the upstream. High values of CHF larger than 2×106W/m2 were obtained only for gap size of 2mm. The result indicates that higher mass velocity in the main heated channel is more effective for the increase in CHF. It was clarified that there is optimum flow rate distribution to obtain the highest values of CHF. For gap size of 2mm, high heat transfer coefficient as much as 7.4×104W/m2K were obtained at heat flux 1.5×106W/m2 under mass velocity 720kg/m2s based on total volumetric flow rate and on the cross section area of main heated channel. Also to obtain high heat transfer coefficient, it is more useful to supply the cooling liquid from the auxiliary unheated channel for additional liquid supply in the transverse direction perpendicular to the flow in the main heated channel.

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