Results for high heat-flux flow realizations in innovative operations of milli-meter scale condensers and boilers

Kivisalu, Michael Toomas; Gorgitrattanagul, Patcharapol; Narain, Amitabh

doi:10.1016/j.ijheatmasstransfer.2014.03.056

Cited by 17 publications

(117 citation statements)

References 26 publications

Supporting

Mentioning

108

Contrasting

Order By: Relevance

“…However, the new generation of electronic systems produces multiple kilowatt waste heat with heat fluxes at a predicted future device level up to 1000 W/cm² (Lee and Mudawar, 2009). To achieve this, innovative condensers and boilers operating in the cyclic regime and interrupted by the negligible effect of gravity must be developed (Kivisalu et al, 2014). The advantages of operating these capacitors in pulsatile mode are also discussed.…”

Section: Introductionmentioning

confidence: 99%

“…The advantages of operating these capacitors in pulsatile mode are also discussed. Such millimeter-scale capacitors (Kivisalu et al, 2014) are of great value in the design of new generation space-based thermal systems and gravity insensitive aircraft-based systems (including avionics cooling).…”

Section: Introductionmentioning

confidence: 99%

“…The controlled heat transfer mechanism in the mini and millimeter channels is thought to be the evaporation of the thin liquid film around the bubbles in the micro-channels (Chen, et al, 2013;Mersen, 2017). There are several general literature reviews of one-dimensional and two-dimensional FC-72 flow boiling and heat transfer, depending on channel geometry (Pereira et al, 2017;Ansys, 2017;Kivisalu et al, 2014;Naik, et al2014).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Numerical Simulation of Annular Flow boiling in Millimeter-scale Channels and Investigation of Design Parameters Using Taguchi Method

Koca

Khalaji

2019

Bilge International Journal of Science and Technology Research

View full text Add to dashboard Cite

As the technology progresses, the electronic components become smaller and at the same time continue to produce more heat, and therefore development of new high heat-flux cooling technologies have become obligatory. The mini and millimeter-scale phase change cooling systems, which have a reduced size and a large surface area where heat transfer can take place, have become an integral part of advanced cooling systems. When comparing phase-change cooling systems with other cooling systems, a relatively low flow rate of very high evaporation heat, which is associated with the phase change for most fluids, allows large amounts of heat to dissipate with flow boiling and substantially solves the many problems. The two-phase cooling technologies used for critical applications include; heat pipes, loop heat pipes and capillary pumped loops which are all passive hence very reliable solutions relying on only capillary effects. Though this passive device cannot meet future high cooling demands because of the limitations of the capillary pumping in terms of heat flux, transport distance and multiple heat source capabilities. On the other hand, in boiling and condensing flows functionality problems arise since at the micrometer and millimeter-scale, shear/pressure forces dominate over gravitational forces and cause thermally hydro-dynamically ineffective/problematic liquid-vapor configurationssuch as plug/slugs flow regimes. For this reason, to overcome the requirement of large amounts of heat transfer from limited spaces and resolving the above problem, novel millimeter-scale phase-change devices should be developed. In this study, for the design of millimeter-scale boilers a 3D Ansys-Fluent© simulation model was developed and numerical simulations were conducted for two different cooling fluids (water and FC-72), different mass flow rates and two different channel heights. Moreover, to examine the simulation results Taguchi method was used. In order to realize thin film annular flow over the boiler surface, employed specific boundary conditions in the 3D simulation model were obtained by means of one dimensional Matlab© simulation code. By means of utilizing the evaluated numerical results, distribution of heat transfer coefficient, vapor quality and pressure drop over the heat transfer surfaces were reported.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Numerical Simulation of Annular Flow boiling in Millimeter-scale Channels and Investigation of Design Parameters Using Taguchi Method

Koca

Khalaji

2019

Bilge International Journal of Science and Technology Research

View full text Add to dashboard Cite

show abstract

“…), are needed for these critical applications. Although some experimental and computational works have been done, and their results reported [1][2][3][4][5][6][7][8][9][10], further experimental and computational evaluations are needed to enable these critical applications.…”

Section: Introductionmentioning

confidence: 99%

“…Past studies [1][2][3][4][5][6][7][8][9][10] focused on consideration of different flow regimes, flow control methods, and estimating heat transfer coefficient related to the particular flow regimes. Various methods of flow regime control have been proposed, such as actively controlled vapor re-circulation in flow condensers and vapor and liquid re-circulation in flow boilers.…”

Section: Introductionmentioning

confidence: 99%

Heat-flux enhancement response for novel flow-boiler operations under resonant, sub-harmonic, and superharmonic imposition of vapor pulsation frequencies relative to a liquid flow-rate pulsation frequency

Koca

Kivisalu

2019

J Braz. Soc. Mech. Sci. Eng.

View full text Add to dashboard Cite

This paper presents fundamental results from experimental investigations of shear/pressure-driven internal flow boiling of FC-72 in a horizontal test section of total flow channel length 1000 mm, gap height 2 mm, and width 15 mm. It compares effects of the frequencies of vapor and liquid pressure fluctuations (pulsations) on the experimentally measured heat-flux rates and heat transfer coefficients at a representative location within the flow boiler under a flow operation method in which re-circulating vapor maintains an annular flow regime over the entire length of the device. For liquid flow/pressure pulsations at 3.8-3.9 Hz, four externally imposed inlet vapor pressure fluctuation conditions were considered: (1) no externally imposed vapor pulsations and (2)-(4): high-amplitude externally imposed vapor pulsations at (2) the same, (3) half, and (4) double the inlet liquid pulsation frequency. Representative pressure differences within the flow boiler are also examined. Local time-averaged heat-flux and heat transfer coefficient responses of these flows are compared with previously published data at the same liquid pulsation frequency, but at a different inlet liquid flow rate, vapor quality, and pressure. The reported measurements, and the discussions and conclusions in this paper, enable better understanding of an established pulsationinduced heat-flux enhancement phenomenon which may be used in future cooling systems to significantly enhance average heat-flux values over the entire length of an annular flow boiler. The main conclusion is that, for the flow conditions investigated, optimal heat transfer efficiency occurs when vapor and liquid pulsations are imposed at the same frequency on the flow-boiler inlet.

show abstract

Internal Annular Flow Condensation and Flow Boiling: Context, Results, and Recommendations

Narain

Prasad

Koca

2018

Handbook of Thermal Science and Engineering

View full text Add to dashboard Cite

Results for high heat-flux flow realizations in innovative operations of milli-meter scale condensers and boilers

Cited by 17 publications

References 26 publications

Numerical Simulation of Annular Flow boiling in Millimeter-scale Channels and Investigation of Design Parameters Using Taguchi Method

Numerical Simulation of Annular Flow boiling in Millimeter-scale Channels and Investigation of Design Parameters Using Taguchi Method

Heat-flux enhancement response for novel flow-boiler operations under resonant, sub-harmonic, and superharmonic imposition of vapor pulsation frequencies relative to a liquid flow-rate pulsation frequency

Internal Annular Flow Condensation and Flow Boiling: Context, Results, and Recommendations

Contact Info

Product

Resources

About