Forced Convective Heat Transfer of Nanofluids in Microchannels

Abstract

Convective heat transfer coefficient and friction factor of a nanofluid in rectangular microchannel were measured. An integrated microsystem consisting of a single microchannel on one side and two localized heaters and five polysilicon temperature sensors along the channel on the other side were fabricated. Aluminum dioxide (Al2O3) nanofluids with various particle volume fractions were used in experiment to investigate the effect of the volume fraction of the nanoparticles to the convective heat transfer and fluid flow in microchannels. The convective heat transfer coefficient of the Al2O3 nanofluid in laminar flow regime was measured to be increased up to 15% compared to the distilled water at a volume fraction of 1.8 volume percent without major friction loss. The Nusselt number measured increases with increasing the Reynolds number in laminar flow regime. A new type of convective heat transfer correlation was proposed to correlate experimental data of heat transfer coefficient for nanofluids in microchannels.

Estimation and experimental study of the density and specific heat for alumina nanofluid

“…The nanofluid in these studies consists mainly of CuO/water [1,2], CuO/ethylene glycol [3], Al 2 O 3 /ethylene glycol [3,4], Al 2 O 3 /water [4][5][6][7][8][9], Al 2 O 3 /ethylene glycol/water [10], TiO 2 /water [8,11], and Ag/methanol nanofluid [12]. Moreover, heat exchangers used in these studies include the microchannel heat sink (MCHS) [1,7,10], miniature-plate heat exchanger [2], plate heat exchangers [3], double-tube flow heat exchanger [3,11], multichannel heat exchanger [5], shell and tube heat exchanger [8], finned tube heat exchanger [9,13], and the thermosyphon heat exchanger [12]. Results of these studies demonstrate that nanofluid could improve the performance of heat exchangers.…”

Experimental and Numerical Analysis of Micro-Scale Heat Transfer Using Graphene Nanofluid in Microchannels for Enhanced Thermal Performance.

“…Due to these particle concentration it shows enhanced thermal conductivity where as micrometer sized particles shows no such enhancement hence nanofluids retain excellence characteristics of enhancing heat transfer rate [13]. The heat transfer coefficients of both nanofluids and pure water at low Reynolds numbers are practically higher than those acquired at high Reynolds number in generally vast microchannels, which demonstrates the heat transfer qualities of microchannels [14].…”

“…Now the question arises to study the behaviour of flow of nanofluids and heat transfer coefficient in microchannels which can be further used to optimize the heat sinks which can be very useful for the development of new technology. Starting the thermal conductivity from Aluminium, Copper, Silver, Diamond upto carbon nanotubes ( Multiwalled carbon nanotubes) there is enhancement in thermal conductivity upto 2000 times then engine oil [4].The heat transfer coefficients of both nanofluidsand pure water at low Reynolds numbers are practically higher than those acquired at high Reynolds number in generally vast microchannels, which demonstrates the heat transfer qualities of microchannels [5]. So, Microchannel miniaturized cooling system device can be successfully utilized for cooling of such systems.…”

Experimental and numerical investigation of heat transfer in CNT nanofluids

“…There are some reports on enhancement in convective heat transfer by nanofluids. [7,[17][18][19][20][21][22][23][24][25][26][27][28][29] However, there are few studies showing inconsistent results as reported by Pak and Cho, [25] Chein and Chuang, [26] Ding et al, [27] Lee and Mudawar [28] and Nelson et al, [29] and also studies showing a decrease in heat transfer coefficient by the addition of nanoparticles to the base fluids. [27,30] The experiments were usually carried out in a pipe or channel flows with constant heat flux.…”