scholarly journals Experimental Investigation of Single-Phase Heat Transfer on Scalable Nanostructured Microchannels

Author(s):  
D. Behera ◽  
D. Mohanty ◽  
D. P. Ghosh ◽  
S. K. Saha ◽  
R. Raj
2002 ◽  
Vol 6 (2) ◽  
pp. 85-97 ◽  
Author(s):  
Gian Piero Celata ◽  
Maurizio Cumo ◽  
Massimo Guglielmi ◽  
Giuseppe Zummo

1989 ◽  
Vol 111 (4) ◽  
pp. 337-343
Author(s):  
G. S. H. Lock ◽  
J. D. Kirchner

The paper reports an experimental investigation of heat transfer in the closed-tube aerosyphon (aerated-thermosyphon) for a range of conditions representative of northern field applications. In particular, attention is focused on the effect of using tubes with heated lengths not only greater than the cooled lengths, but very much greater than the tube diameter. Using three heated sections and one cooled section, the geometry of the device has been varied systematically with 10 < LH/d < 50 and 1 < LH/LC < 20. For any given geometry, the effect of air bubbling rate has been studied in the range of 0 < V˙ < 5 × 10−5 m3/S. Using these ranges it has been possible to make comparisons with other thermosyphon and aerosyphon data. The results indicate that heat transfer coefficients are reduced by increasing either length-diameter ratio or heated-cooled length ratio. They also reveal that, in general terms, the aerosyphon is almost an order-of-magnitude more effective than the single-phase thermosyphon. Some obervations on the flow regimes are offered, and an empirical correlation is presented.


1987 ◽  
Vol 109 (2) ◽  
pp. 300-307 ◽  
Author(s):  
J. P. Chiou

Results of the experimental investigation of a class of spiral spring coil used as a tube side heat transfer augmentative device for a single phase cooling mode operation are presented. SAE 10 engine oil flowing inside the tube is cooled by water flowing outside the tube. This spiral spring insert is inexpensive but it can increase the tube side heat transfer coefficient significantly. Thus its use as an augmentative device is effective. Application of this device in the design of oil coolers is discussed.


Author(s):  
Dong Liu ◽  
Leyuan Yu

Nanofluids have been proposed as a promising candidate for advanced heat transfer fluids in a variety of important engineering applications. A consensus is now lacking on if and how the dispersed nanoparticles alter the thermal transport in convective flows. An experimental investigation was conducted to study single-phase forced convection of Al2O3-water nanofluid in a circular minichannel. The friction factor and convection heat transfer coefficients were measured for nanofluids of various volume concentrations (up to 5%) and were compared to these of the base fluid. The Reynolds number varied from 600 to 4500, covering the laminar, transition and early fully developed turbulent regions. It was found that the nanofluids exhibit pronounced entrance region behaviors in the laminar region. In the transition and turbulent regions, the onset of transition to turbulence is delayed in nanofluids. Further, both the friction factor and convective heat transfer coefficient are below these of water at the same Re in the transition flow. Once fully developed turbulence is established, the difference in the flow and heat transfer of nanofluids and water will diminish. A scaling analysis showed these behaviors may be attributed to the variation in the relative size of nanoparticle with respect to the turbulent microscales. This work suggests that the particle-fluid interaction has a significant impact on the flow physics of nanofluids, especially in the transition and turbulent regions. Consequently, nanofluids should be used in either the laminar flow or fully developed turbulent flow at sufficiently high Re in order to yield enhanced heat transfer performance.


Author(s):  
O.V. Abyzov ◽  
Yu.V. Galyshev ◽  
A.K. Ivanov

Liquid cooling of cylinder and piston parts in highly boosted internal combustion engines is generally accompanied by local phase transition phenomena, such as surface nucleate boiling. The heat transfer coefficient of nucleate boiling is several times higher than that of single-phase convection. In order to efficiently exploit the thermal effect of nucleate boiling in cooling systems, simultaneously preventing emergency supercritical modes, a deeper understanding of boiling physics based on full-scale experiments is required. We conducted experimental investigation of heat transfer in a simulated cooling duct of a piston engine cylinder head, using a bespoke motor-free installation. We studied the effects of velocity, flow character and coolant type on the heat transfer, accounting for the presence of congestion regions. Over the course of the experiment, we simulated thermal conditions characteristic of different heat transfer types: single-phase convection, nucleate boiling, the onset of boiling crisis. We used the experimental data to plot the coolant heat flow density as a function of wall temperature for different measuring points situated inside the stream and the turbulent flow regions (congestion regions). We show that the mature nucleate boiling mode is the most favourable in terms of how uniform the temperature field within a part is. The experimental data obtained during the investigation may be used to verify mathematical simulations in the two-phase heat transfer theory, provided the data have been appropriately processed


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