Limits to Critical Heat Flux Enhancement in a Liquid Film Falling Over a Structured Surface That Simulates a Microelectronic Chip

Anderson

1990

110

A high power electronic chip was simulated experimentally to investigate upper cooling capabilities using a variety of pool boiling enhancement techniques. Parametric effects of system pressure, subcooling, surface augmentation, and choice of coolant on boiling heat transfer from a vertical 12.7 × 12.7 mm2 flat surface were examined. The two fluorocarbon coolants tested, FC-72 and FC-87, resulted in similar boiling curves, but FC-87 significantly reduced chip surface temperature for a given heat flux. Increasing pressure enhanced boiling performance and critical heat flux slightly. However, the significant increase in chip temperature, and the practical problems associated with packaging electronic hardware in a pressurized environment precluded pressurization as a viable enhancement option. Subcooling was very effective in increasing critical heat flux and significantly reducing bubble size and growth of the bubble boundary layer on the chip surface. Surface augmentation was also effective in enhancing critical heat flux; however, some surface geometries promoted noticeable temperature excursion at incipience.

Section: Introductionmentioning

confidence: 99%

Parametric Investigation Into the Effects of Pressure, Subcooling, Surface Augmentation and Choice of Coolant on Pool Boiling in the Design of Cooling Systems for High-Power-Density Electronic Chips

Anderson

1990

110

“…The last decade witnessed the development of many innovative approaches to cooling high-flux electronic hardware. These include enhanced pool boiling (Nakayama et al, 1984;Anderson and Mudawar, 1989;Mudawar and Anderson, 1990), flow boiling (Maddox and Mudawar, 1989;Maddox, 1989, 1990), falling films (Grimley et al, 1988), jet impingement (Monde and Katto, 1978;Ma and Bergles, 1983;Mudawar, 1990,1992), curved flow (Galloway and Mudawar, 1992), and microchannels (Tuckerman and Pease, 1981;Phillips, 1988;Bowers and Mudawar, 1993). Key to enhancing cooling effectiveness in most of these approaches has been the direct (immersion) cooling of the device with a dielectric liquid.…”

Section: Introductionmentioning

confidence: 99%

Immersion-Cooled Standard Electronic Clamshell Module: A Building Block for Future High-Flux Avionic Systems

Jimenez

Morgan

1994

An 820-Watt clamshell module was fabricated and tested in order to assess the feasibility of cooling future high heat flux avionic hardware via subcooled phase change. One half of the module was constructed from aluminum 7075-T6 and populated with 16 heat sources simulating microelectronic chips. The other half was substituted with a transparent plastic cover to facilitate optical access to the boiling taking place in the module cavity. A dielectric coolant, Fluorinert FC-72, was supplied to, and rejected from the module via sleeveless quick connection couplers. Tests were performed with an inlet coolant pressure of 1.52 bar (22 psia) and inlet temperatures ranging from 27 to 47°C. These tests yielded power dissipation exceeding 410 W per half module for coolant flow rates and pressure drops as small as 0.023 kg/s (0.221 gpm) and 0.149 bar (2.16 psia), respectively, and the device and rib guide temperatures were maintained below 80 and 60°C, respectively. The pressure drop remained constant with increasing module power proving, as was confirmed visually, it is possible to condensate all the vapor within the module cavity, allowing only liquid to exit the module. Thus, coolant conditioning external to the module can be greatly simplified by employing a simple single-phase liquid flow loop.

“…While direct immersion has been studied in the context of single-phase forced convection (Tuckerman and Pease, 1981;Samant and Simon, 1986;Ramadhyani and Incropera, 1987;Maddox and Mudawar, 1989;Mudawar and Maddox, 1989), falling films (Mudawar et al, 1987;Grimley et al, 1988), and flow boiling (Samant and Simon, 1986;Maddox and Mudawar, 1989;Mudawar and Maddox, 1989;McGillis et al, 1991), pool boiling remains a very attractive cooling option due to the unique attribute of passive fluid circulation. Having no mechanical pumps, pool boiling hardware are less complex, easier to seal and free of pump-induced fluid pulsation.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Enhanced Surfaces for High Flux Chip Cooling by Pool Boiling

Anderson

1993

105

A high flux electronic chip was numerically and experimentally simulated to investigate pool boiling capabilities of enhanced metallic surface attachments built upon a 12.7 × 12.7 mm2 base area. It is shown how experimental nucleate boiling data for a flat chip and for chips with low-profile microstructures can be used as input boundary conditions in the numerical prediction of boiling performances of high flux, smooth and microstructured extended cylindrical surfaces. A technique for extending the applicability of the numerical results to cylindrical fin arrays is demonstrated with the aid of experimental data obtained for these surfaces. Surface enhancement resulted in chip planform heat fluxes of 105.4 and 159.3 W/cm2, for saturated and 35°C subcooled FC-72, respectively.