Turbulent two phase approach model for the nanofluids heat transfer analysis flowing through the minichannel heat sinks Paisarn Naphon ⇑ , Lursukd Nakharintr Thermo-Fluid and Heat Transfer Enhancement Research Lab. (TFHT), Department of Mechanical Engineering, Faculty of Engineering, Srinakharinwirot University, 63 Rangsit-Nakhornnayok Rd., Ongkharak, Nakhorn-Nayok 26120, Thailand article info Article history: Received 16 June 2014 Received in revised form 5 November 2014 Accepted 6 November 2014 Keywords: Nanofluids Minichannel heat sink Convective heat transfer abstract This study presents the numerical simulation of the turbulent heat transfer and flow characteristics of nanofluids in the minichannel heat sink. The minichannel heat sink is fabricated from the copper by the wire electrical discharge machine with the length, the width and the fin height of 110, 60, 1 mm, respectively. Experiments are done at various nanofluids Reynolds numbers in the ranging of 80–200. The k–e two equations turbulence model with single phase approach model, mixture two phase approach model and VOF approach model are employed to describe the heat transfer and flow characteristics. It is found that reasonable agreement is obtained from the comparison between the predicted results and the measured data. Two phase models (mixture two phase and VOF) are more appropriate the homogeneous model (single phase). In addition, the results obtained from the nanofluids cooling method are compared with those from the de-ionized water cooling method. The suspending nanoparticles have significant effect on the enhancement of heat transfer. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Development in the microfabrication technologies results in the production of very small scale electronic devices with high performance. Which higher performance electronics device generates considerably more heat than a lower performance device. Due to the heat generation in high level, space limitation, and coolant-cooling limitation, the development of the micro- components of the heat transfer devices have been introduced as one of the heat transfer enhancement technique. The heat transfer and flow characteristics in the mini and micro-channel have been continuously studied by researchers. Experimentally investigated on the forced convective heat transfer and flow characteristics in the microchannel are presented. Lee et al. [1] studied the heat transfer characteristics in the microchannels with various configu- rations. The single phase liquid heat transfer characteristics and pressure drop in microchannel for electronic cooling packages is considered by Zhang et al. [2], Steinke and Kandlikar [3], Hrnjak and Tu [4]. The single phase flow and heat transfer characteristics in the minichannel heat sink with various fin configurations are analyzed by the numerical method [5–10]. In general, air and water are the most frequently used coolant in the heat transfer devices. Due to the high level of generated heat and working fluid transport properties limitation, one of the methods for the heat transfer enhancement is the application of additives to the working fluids to change the fluid transport properties and flow features. Therefore, in order to further enhance thermal perfor- mance of heat transfer devices, the use of nanofluids is proposed. As compared to conventional liquid for cooling performance, nanofl- uids advantages are summarized as follows: reduced pumping power to achieve equivalent heat transfer intensification, high spe- cific surface area, reduced particle clogging thus promoting system miniaturization and high dispersion stability with predominant Brownian motion of particles. Recent researches have indicated that substitution of conventional coolants by nanofluids appears prom- ising. Nanofluids are potential heat transfer fluids with enhanced thermophysical properties and heat transfer enhancement can be applied in many heat transfer devices for better performances; nanofluids in engine cooling, solar water heating, cooling of elec- tronics, cooling of heat exchanging devices, improving heat transfer efficiency of chillers, domestic refrigerator–freezers and cooling in machining. Koo and Kleinstreuer [11] simulated the steady laminar liquid nanofluid flow in microchannels. Chein and Huang [12] ana- lyzed the silicon microchannel heat sink performance using pure and nanoscale Cu with various volume fractions as coolant. Jang and Choi [13] numerically investigated the cooling performance of a microchannel heat sink with nanofluid as coolant. Chein and Chu- ang [14] studied the microchannel heat sink performance using nanofluids as coolants. Experiments were performed to verify the http://dx.doi.org/10.1016/j.ijheatmasstransfer.2014.11.024 0017-9310/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +66 3 7322625x2113; fax: +66 3 7322609. E-mail address: paisarnn@swu.ac.th (P. Naphon). International Journal of Heat and Mass Transfer 82 (2015) 388–395 Contents lists available at ScienceDirect International Journal of Heat and Mass Transfer journal homepage: www.elsevier.com/locate/ijhmt