Enhanced Extended-Surfaces for Two-Phase Pump-Less Cooling Loops
type: CreativeWork
description: Pool boiling experiments are conducted to investigate the heat transfer performance of screen laminate-enhanced extended surfaces in water at reduced pressures. A lamination of fine-filament, wire mesh is an effective surface enhancement for boiling since the surface can be configured to provide a very high density of potential bubble nucleation sites. A coating of copper fine wire screen is bonded to an extended surface (fin). The coating thickness ranged from 0.21mm to 1.3mm. The porosity of the coatings is held constant at 0.43 and the pore hydraulic diameter of the coating varies from 39μm to 172μm. Pool temperatures are held at the saturation temperature for water at pressures of 0.2, 0.3, 0.5 and 1.0atm. A reduction in pressure reduces the boiling performance for all surfaces.The work began by investigating 4-layer laminates on a fin that has a 1cm2 base cross section area, a 5deg taper with heights of 1cm and 2/3cm. Boiling performance of a vertical and horizontal fin orientation is investigated. The 4 layer screen laminate enhanced fin with a 10K superheat sustains base heat fluxes of up to 140 W/cm 2 at 1.0atm, and up to 132W/cm 2 at 0.2atm. These extended surfaces outperform screen laminates enhanced plane surface by up to 4 fold. Vertically oriented fins outperform horizontal fins.The second part of the work was to further investigate screen laminates on the trapezoidal fin. Laminations of 8-layers are found to improve boiling performance over the four layers. Experimental results show that the thin, fine coatings on the fin surfaces enhance the boiling performance. At 0.2atm base heat fluxes in excess of 193W/cm 2 are seen and with moderate superheats of around 10K. A semi-empirical model of the fin is developed. The model implements a boiling correlation from a plane enhanced surface. Assessments of fin aspect ratio and taper are conducted using the model. Larger aspect ratios improve fin performance. The effects of the taper are negligible.The last par…
abstract: Pool boiling experiments are conducted to investigate the heat transfer performance of screen laminate-enhanced extended surfaces in water at reduced pressures. A lamination of fine-filament, wire mesh is an effective surface enhancement for boiling since the surface can be configured to provide a very high density of potential bubble nucleation sites. A coating of copper fine wire screen is bonded to an extended surface (fin). The coating thickness ranged from 0.21mm to 1.3mm. The porosity of the coatings is held constant at 0.43 and the pore hydraulic diameter of the coating varies from 39μm to 172μm. Pool temperatures are held at the saturation temperature for water at pressures of 0.2, 0.3, 0.5 and 1.0atm. A reduction in pressure reduces the boiling performance for all surfaces.The work began by investigating 4-layer laminates on a fin that has a 1cm2 base cross section area, a 5deg taper with heights of 1cm and 2/3cm. Boiling performance of a vertical and horizontal fin orientation is investigated. The 4 layer screen laminate enhanced fin with a 10K superheat sustains base heat fluxes of up to 140 W/cm 2 at 1.0atm, and up to 132W/cm 2 at 0.2atm. These extended surfaces outperform screen laminates enhanced plane surface by up to 4 fold. Vertically oriented fins outperform horizontal fins.The second part of the work was to further investigate screen laminates on the trapezoidal fin. Laminations of 8-layers are found to improve boiling performance over the four layers. Experimental results show that the thin, fine coatings on the fin surfaces enhance the boiling performance. At 0.2atm base heat fluxes in excess of 193W/cm 2 are seen and with moderate superheats of around 10K. A semi-empirical model of the fin is developed. The model implements a boiling correlation from a plane enhanced surface. Assessments of fin aspect ratio and taper are conducted using the model. Larger aspect ratios improve fin performance. The effects of the taper are negligible.The last par…
author: Laca, Paul
keywords: Numerical Model, Pool Boiling, Reduced-Pressure, Screen-Laminates, Two-Phase, Water
date published: 2010
date modified: 2026-07-27T21:47:25Z
provider: University of Nevada - Reno
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Nevada - Reno

PropertyValue
property ID: Handle
value: http://hdl.handle.net/11714/4316