Computational Investigation of Heat Transfer of Nanofluids in Microchannel with Improper Insulation
Numerical simulation of heat transfer of nanofluids in rectangular microchannel has been performed. A micro-electro-mechanical system is built with two heating resistors embedded in a silicon substrate. Microchannel made from polydimethylsiloxane is plant
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Abstract. Numerical simulation of heat transfer of nanofluids in rectangular microchannel has been performed. A micro-electro-mechanical system is built with two heating resistors embedded in a silicon substrate. Microchannel made from polydimethylsiloxane is planted in the substrate and nanofluids with different volume fractions are used as the coolant. Because of the not well-insulated micro-electro-mechanical system, heat generated by the heating resistors will be lost to the surrounding as well as carried away by the nanofluids through the microchannel. Heat transfer is analyzed at low Reynolds number for different nanofluid concentrations. Keywords: Nanofluid
Convective heat transfer Microchannel
1 Introduction Nowadays heat exchange is an important problem in industry. Electronics devices, such as electronic cooling system, network server or integrated data center, have high requirement of cooling in tiny space. Convective heat transfer is a very effective method for this situation, heat flux of the order of 107 W/m2 can be transferred in micro channels with a surface temperature below 71 °C [1]. The thermal efficiency can be improved in many ways. The most obvious methods are increase contact area or increase flow rate, but these methods may need to modify the device design or add extra pump. Another suggestion is to increase the conductivity of coolant, for example, mix high conductivity material into cooling liquid. Due to the technical limitation in the early days, the adding of micrometer scale particles in the coolant may lead to increase of friction and hence results in clogging of the microchannel. Lately, nanoscale particles are selected as constituents to add into the coolant. The most common nanoparticles that are used can be cataloged as ceramic particles, pure metallic particles, and carbon nanotubes (CNTs). Nanofluid, a fluid containing nanometer-sized particles, has novel properties compared with its base fluid. Numerous literatures indicate that the nanofluids can increase the convective heat transfer coefficient and friction factor, but there are still some reports show that the heat transfer may not be improved. There are several experiments in the regard, but they did not show satisfactory evidence [2, 3]. © Springer International Publishing Switzerland 2016 O. Gervasi et al. (Eds.): ICCSA 2016, Part I, LNCS 9786, pp. 505–513, 2016. DOI: 10.1007/978-3-319-42085-1_39
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V.K. Sin et al.
Enhancement of heat transfer is not obvious in [3]. Such a finding is different from many studies in the literature, although there are some studies which do show the increase of heat transfer by nanofluids [4, 5]. Further study on the energy budget of the system in [3] indicates that “heat loss” in the system is significant. Rate of heat carried away by the coolant is less than the heat generated by the electric power input, and the former is only a few percent to about fifty percent of the latter, depending on the Reynolds number of the flow. It indicates that the entire system in [3] is not well-insul
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