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|Nanofluid Pool Boiling and Microchannel Forced Convective Heat Transfer Investigations using an Instrumented Glass Device|
|Keywords: Phase change, microchannel, nanofluids|
|Increase in the spatial density of electronic components in the chip board assembly has led to the need for dissipation of high heat fluxes. This combined with the limitations on the chip operating temperature and the shortcomings of the current cooling techniques has made thermal management of chips a critical task. Nanofluid (dispersions of nanostructures in liquids) pool boiling and microchannel cooling which involves single phase and two phase heat transfer are potential candidates for future thermal management solutions. This is because of an enhancement in the critical heat flux (CHF) with nanofluids and significantly high heat transfer coefficients at comparatively lower flow rates for forced convective boiling. A quantitative understanding of heat transfer phenomena in the microscale regime requires precise data reduction for temperature and heat flux measurements. The current state-of-art devices for pool boiling experiments and microchannels and microtubes are fabricated in silicon, stainless steel, or copper. Conduction losses through these high thermal conductivity materials may result in conjugate effects and experimental uncertainties. The objective of the present work is to study the nanofluids pool boiling behavior and forced convective phase change phenomena using the proposed MEMS device microfabricated in glass. Different nanofluids (single wall and multi-wall carbon nanotubes, and nickel nanoparticles) were tested for pool boiling and two flow rates were used for investigating phase change heat transfer for flow boiling experiments. The low value of thermal conductivity of glass helps minimize conduction losses and improves the accuracy of the measured local heat transfer coefficients, local heat flux, temperature, and Nusselt number. Moreover, the transparent nature of the substrate helps in the visualization purposes of flow conditions during two phase experiments.|
|Abhishek Jain, Ph.D. Student
Rensselaer Polytechnic Institute