Low thermal conductivity is a primary limitation in the development of energy-efficient heat transfer fluids that are required in many industrial applications. In this paper we propose that an innovative new class of heat transfer fluids can be engineered by suspending metallic nanoparticles in conventional heat transfer fluids. The resulting {open_quotes}nanofluids{close_quotes} are expected to exhibit high thermal conductivities compared to those of currently used heat transfer fluids, and they represent the best hope for enhancement of heat transfer. The results of a theoretical study of the thermal conductivity of nanofluids with copper nanophase materials are presented, the potential benefits of the fluids are estimated, and it is shown that one of the benefits of nanofluids will be dramatic reductions in heat exchanger pumping power.

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Investigation on Convective Heat Transfer and Flow Features of Nanofluids

An introduction to heat transfer

In this review we focus on recent developments in applications of bio-inspired special wettable surfaces. We highlight surface materials that in recent years have shown to be the most promising in their respective fields for use in future applications. The selected topics are divided into three groups, applications of superhydrophobic surfaces, surfaces of patterned wettability and integrated multifunctional surfaces and devices. We will present how the bio-inspired wettability has been integrated into traditional materials or devices to improve their performances and to extend their practical applications by developing new functionalities.

Applications of Bio‐Inspired Special Wettable Surfaces

This paper explores the recent research developments in high-heat-flux thermal management. Cooling schemes such as pool boiling, detachable heat sinks, channel flow boiling, microchannel and mini-channel heat sinks, jet-impingement, and sprays, are discussed and compared relative to heat dissipation potential, reliability, and packaging concerns. It is demonstrated that, while different cooling options can be tailored to the specific needs of individual applications, system considerations always play a paramount role in determining the most suitable cooling scheme. It is also shown that extensive fundamental electronic cooling knowledge has been amassed over the past two decades. Yet there is now a growing need for hardware innovations rather than perturbations to those fundamental studies. An example of these innovations is the cooling of military avionics, where research findings from the electronic cooling literature have made possible the development of a new generation of cooling hardware which promise order of magnitude increases in heat dissipation compared to today's cutting edge avionics cooling schemes.

Assessment of high-heat-flux thermal management schemes

Superhydrophobic and superoleophobic surfaces have so far been made by roughening a hydrophobic material. However, no surfaces were able to repel extremely-low-energy liquids such as fluorinated solvents, which completely wet even the most hydrophobic material. We show how roughness alone, if made of a specific doubly reentrant structure that enables very low liquid-solid contact fraction, can render the surface of any material superrepellent. Starting from a completely wettable material (silica), we micro- and nanostructure its surface to make it superomniphobic and bounce off all available liquids, including perfluorohexane. The same superomniphobicity is further confirmed with identical surfaces of a metal and a polymer. Free of any hydrophobic coating, the superomniphobic silica surface also withstands temperatures over 1000°C and resists biofouling.

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Turning a surface superrepellent even to completely wetting liquids

Description de 3 algorithmes d'ordinateurs developpes pour le calcul des performances des tours de refroidissement, des refroidisseurs de fluide par evaporation et des condenseurs a evaporation disponibles sur le marche. Analyse de cas pour chacun des 3 types d'echangeurs

Performance simulation of evaporative heat exchangers-(cooling towers, fluid coolers and condensers)

COMPACT HEAT EXCHANGERS Compact and Enhanced Heat Exchangers

Prediction of two-phase heat transfer in a 4-pass evaporator bundle using single tube experimental data

Numerical Study of Turbulent Flow and Heat Transfer in Micro-Fin Tubes – Part 1, Model Validation

An analytically based computer program was used to calculate the performance benefits provided by the use of enhanced tube geometries in an R-11 flooded refrigerant evaporator. Three different boiling surface geometries are evaluated: integral fins, and two different high-performance enhanced boiling surface geometries. Four water-side surface geometries are evaluated: a plain surface, a 10-ridge ribbed tube, a 30-ridge ribbed tube, and a corrugated tube. The performance analysis is applied to a 250-ton (879-kW) R-11 chiller operating at full load condition. The reference evaporator bundle has 180 tubes 135 in. (3.43 m7rpar; long, with two water-side passes. The analysis compares the performance benefits provided by the enhanced boiling surface with a plain internal diameter (ID7rpar; and with an enhanced ID. Analysis are provided to define the shell length reduction for specified operating conditions, and to define how much the saturation temperature may be increased for a bundle of fixed size. Analysis ...

Ralph L. Webb

Papers

Performance simulation of evaporative heat exchangers-(cooling towers, fluid coolers and condensers)

COMPACT HEAT EXCHANGERS Compact and Enhanced Heat Exchangers

Prediction of two-phase heat transfer in a 4-pass evaporator bundle using single tube experimental data

Numerical Study of Turbulent Flow and Heat Transfer in Micro-Fin Tubes – Part 1, Model Validation

Performance of Flooded Refrigerant Evaporators with Enhanced Tubes