Author
Ralph L. Webb
Bio: Ralph L. Webb is an academic researcher from Pennsylvania State University. The author has contributed to research in topics: Heat transfer & Boiling. The author has an hindex of 50, co-authored 151 publications receiving 8672 citations.
Papers published on a yearly basis
Papers
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01 Mar 1994
TL;DR: In this article, the authors evaluated two-phase heat exchangers for single-phase flows and showed that they can achieve state-of-the-art performance in terms of heat transfer.
Abstract: Heat Transfer Fundamentals Performance Evaluation for Single-Phase Flows Performance Evaluation Criteria for Two-Phase Heat Exchangers Plate-and-Fin Extended Surfaces Externally Finned Tubes Insert Devices for Single-Phase Flow Internally Finned Tubes and Annuli Integral Roughness Fouling on Enhanced Surfaces Pool Boiling Vapor Space Condensation Convective Vaporization Convective Condensation Enhancement Using Electric Fields Simultaneous Heat and Mass Transfer Additives for Gases and Liquids Problem Supplement Index.
1,296 citations
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TL;DR: In this paper, a broad range of Performance Evaluation Criteria (PEC) applicable to single-phase flow in tubes is presented and detailed procedures are outlined to calculate the performance improvement and to select the optimal surface geometry.
802 citations
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TL;DR: In this paper, a single-phase forced convection in a circular tube containing a two-dimensional rib roughness was investigated and the authors extended the state-of-the-art by examining the effect of the rib helix angle.
461 citations
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TL;DR: In this article, a new correlation for two-phase friction pressure drop in small diameter tubes was developed by modifying the Friedel correlation, which predicts 119 data points with a mean deviation of 11.5%.
339 citations
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TL;DR: In this article, an analytical model was developed to predict the heat transfer coefficient and friction factor of offset strip-fin heat exchanger surface geometry. But the model was not applied to the LAMINAR and TURBORN flow regimes.
244 citations
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TL;DR: In this article, an innovative new class of heat transfer fluids can be engineered by suspending metallic nanoparticles in conventional heat-transfer fluids, which are expected to exhibit high thermal conductivities compared to those of currently used heat transfer fluid, and they represent the best hope for enhancing heat transfer.
Abstract: 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.
4,634 citations
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TL;DR: This review 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.
Abstract: 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.
968 citations
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TL;DR: This paper explores the recent research developments in high-heat-flux thermal management and demonstrates 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.
Abstract: 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.
824 citations
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TL;DR: In this article, the authors showed that 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.
Abstract: 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.
821 citations