Continuous nanofluids jet impingement heat transfer and flow in a micro-channel heat sink P. Naphon ⇑ , L. Nakharintr, S. Wiriyasart Thermo-Fluid and Heat Transfer Enhancement 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 29 January 2018 Received in revised form 18 May 2018 Accepted 19 May 2018 Keywords: Micro-channel heat sink Nanofluids Jet impingement abstract Experimental investigation on the TiO 2 nanofluids jet impingement heat transfer and flow characteristics in the micro-channel heat sink are carried out. In the present study, three heat transfer enhancement techniques; micro-channel heat sink, jet impingement, and nanofluids are considered in which included the effect of relevant parameters of the nanofluids concentration, nozzle diameter, nozzle-to-heat sink distances, mass flow rate of nanofluids on the heat transfer performance of a micro-channel heat sink are considered. The obtained results showed that the suspending of nanoparticles in the base fluid remarkably increases the convective heat transfer by 18.56% at 0.015% nanofluids concentration. In addi- tion, the obtained heat transfer coefficient tends to increase with increasing the nozzle diameter and decreasing nozzle level height. While the pressure drop across the test section increases as the nozzle diameter decreases and nozzle level height increases. However, the suspending of nanoparticles bring almost no extra addition of pressure drop as comparing with the base fluid. However, the obtained results point out that the proper selection of the relevant parameters to enhancement of heat transfer is important. Ó 2018 Elsevier Ltd. All rights reserved. 1. Introduction Due to high-density electronic components, small scale of elec- tronic devices, and high generated heat rate, the dissipation of the generated heat is a momentous embarrassment. Therefore, many innovative ideas have been proposed for thermal cooling enhance- ment in the electronic devices. The most common heat transfer enhancement technique is the miniaturized technology, mini and micro-components with jet impingement technique for the elec- tronic devices. There are some studies on the jet impingement heat transfer in the various configurations heat sink. For example, Naphon et al. [1,3] experimentally and numerically investigated the heat transfer characteristics of the jet liquid impingement with three different configurations heat sinks for the central processing unit of a personal computer. Effects of outlet port positions on the jet liquid impingement heat transfer characteristics. Yang and Lai [2,4] numerically studied the forced convection flow of Al 2 O 3 - water nanofluid in the radial flow cooling system using a single- phase approach model. Li et al. [5] applied the RANS-based k-u SST turbulence model to analyze the heat transfer and hydrody- namic behavior of various types of water-based nanofluids inside a typical radial flow. Lelea and Laza [6,12] presented the thermal and hydrodynamic analysis of the micro-heat sink with straight microtubes and multiple inlet jets. Dai et al. [7] studied a flow sep- aration technique including pressure drop and heat transfer in the increased flow area. Jaberi et al. [8] studied heat transfer character- istics of nanofluids in the impingement of a fluid jet on a flat circu- lar disk. Trainer et al. [9] experimentally studied the heat transfer performance of air-assisted liquid water jets impingement. Seyf et al. [10] presented a three-dimensional model describing thermal and hydrodynamic characteristics of a micro-tube heat sink. Kurnia et al. [11] evaluated the heat transfer performance of laminar non- Newtonian fluid flow in various configurations of coiled square tubes. Yue et al. [13] analyzed the hydraulic and thermal perfor- mances of a manifold micro-channel heat sink with and without nanofluids as working fluids. Xia et al. [14] experimentally and numerically studied the temperature distribution, flow field and pressure drops of the current complex corrugation micro-channel heat sink. Haridas et al. [15] presented the performance evaluation of two type nanofluids in the context of compact channels. Gong et al. [16] numerically studied the structures of micro-channel heat sinks for chip cooling. Srikanth et al. [17] studied on the multi- objective geometric optimization of a PCM based matrix type com- posite heat sink. Zhang et al. [18] numerically investigated the con- fined jet array impingement cooling with spent flow distraction https://doi.org/10.1016/j.ijheatmasstransfer.2018.05.101 0017-9310/Ó 2018 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: paisarnn@g.swu.ac.th (P. Naphon). International Journal of Heat and Mass Transfer 126 (2018) 924–932 Contents lists available at ScienceDirect International Journal of Heat and Mass Transfer journal homepage: www.elsevier.com/locate/ijhmt