Heat transfer improvement of water/single-wall carbon nanotubes (SWCNT) nanofluid in a novel design of a truncated double-layered microchannel heat sink Ali Akbar Abbasian Arani a , Omid Ali Akbari b , Mohammad Reza Safaei c,d,⇑ , Ali Marzban e , Abdullah A.A.A. Alrashed f , Gholam Reza Ahmadi b , Truong Khang Nguyen c,d a Department of Mechanical Engineering, University of Kashan, Kashan, Iran b Young Researchers and Elite Club, Khomeinishahr Branch, Islamic Azad University, Khomeinishahr, Iran c Division of Computational Physics, Institute for Computational Science, Ton Duc Thang University, Ho Chi Minh City, Vietnam d Faculty of Electrical and Electronics Engineering, Ton Duc Thang University, Ho Chi Minh City, Vietnam e Department of Mechanical Engineering, Aligoudarz Branch, Islamic Azad University, Aligoudarz, Iran f Department of Automotive and Marine Engineering Technology, College of Technological Studies, The Public Authority for Applied Education and Training, Kuwait article info Article history: Received 7 April 2017 Received in revised form 22 May 2017 Accepted 22 May 2017 Keywords: Heat sink Single-wall carbon nanotubes Truncated double-layered microchannel Performance evaluation criteria abstract In the present study, laminar flow and heat transfer of nanofluid water/single-wall carbon nanotubes have been investigated in a novel design of double layered microchannel heat sink (MCHS). Present inves- tigation has studied the dimensionless values of truncated lengths (k) of 0, 0.4, 0.8 and 1. Studied Reynolds numbers were 500, 1000 and 2000. The effect of volume fraction of nanoparticles in the Newtonian suspension of water based nanofluid was studied for values of 0, 0.04 and 0.08. The results showed that the thermal resistance and ratio of maximum and minimum temperature difference for bot- tom wall of microchannel as well as the ratio of thermal resistance decrease by increasing the nanopar- ticles volume fraction and decrement of k. The Performance evaluation criteria (PEC) factor on the bottom of channel increases in all ratios of k by augmenting volume fraction of nanoparticles. Ó 2017 Elsevier Ltd. All rights reserved. 1. Introduction From 1960s, downsizing was an important tendency in science and technology. Micro-Electro-Mechanical Systems (MEMS) gen- erate notable heat during their operations, while custom coolants do not have sufficient cooling ability for thermal removal of the high-tech industries. Furthermore, by adding solid micro-sized particles to these coolants, they cannot be used in applicable cooling systems. Because they are too enormous size for flowing in the narrow channels and demanded cooling of MEMS systems. Since the nanoparticles can flow in microchannels without sedi- mentation, they can be considered as proper cooling fluids. They can improve cooling systems of MEMS in high heat flux condi- tions. Nanofluids can be used for improvement of thermal man- agement systems in engineering applications. Nowadays, many industries need heat transfer optimizations. For instance, trans- portation industry has a critical demand for improvement of cool- ing fluids operation in transportation facilities. Nanofluids can provide the possibility of efficient heat transfer in engines, pumps, radiators and other small components. Lighter transport services can traverse more distance by less amount of fuel. Effi- cient transport services decrease the expenses due to lower energy consumption. Also, low fuel consumption will lead to less demand of fuel and will reduce the environmental pollution. Therefore, nanofluids can have vital roles in transportation systems. In 1981, the first microchannel heat sink (MCHS) presented with silicon surface and parallel micro scale channels. In two recent decades, due to the capacity of transferring high heat flux from a small surface, microchannel heat sinks have been investi- gated. In recent decades, noticeable progresses for producing micro instruments in the electronics industry have been achieved [1]. Nowadays, the considerable progress of micro-building tech- niques has made the microchannels to be able to have various practicable functions on several areas. Because of importance of heat transfer issue in microchannels, numerous investigations about heat transfer issue in microchannels and other geometries have been studied by researchers [2–5]. Akbari et al. [6] numeri- cally studied the effects of ribs on laminar flow and heat transfer http://dx.doi.org/10.1016/j.ijheatmasstransfer.2017.05.089 0017-9310/Ó 2017 Elsevier Ltd. All rights reserved. ⇑ Corresponding author at: Ton Duc Thang University, Ho Chi Minh City, Vietnam. E-mail address: cfd_safaei@tdt.edu.vn (M.R. Safaei). International Journal of Heat and Mass Transfer 113 (2017) 780–795 Contents lists available at ScienceDirect International Journal of Heat and Mass Transfer journal homepage: www.elsevier.com/locate/ijhmt