Experimental analysis of heat transfer behavior of silver, MWCNT and hybrid (silver +MWCNT) nanofluids in a laminar tubu
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Experimental analysis of heat transfer behavior of silver, MWCNT and hybrid (silver +MWCNT) nanofluids in a laminar tubular flow Munish Gupta1 · Vinay Singh2 · Sandeep Kumar3 · Neeraj Dilbaghi3 Received: 10 September 2019 / Accepted: 14 February 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract Experimental investigations were carried out in order to study the heat transfer performance of silver (Ag), multiwalled carbon nanotubes (MWCNT) and silver (Ag) + multiwalled carbon nanotubes (Ag + MWCNTs) dispersed in distilled water. Nanofluids were synthesized and characterized using different techniques. Experimental facility was fabricated to validate the heat transfer performance of nanofluids in the laminar flow. The nanofluids were tested at mass concentrations of 0.02%, 0.05%, 0.1%, 0.2% and 0.5% for all the three nanofluids. Experimental average heat transfer coefficient was evaluated as a function of Reynolds number. The highest heat transfer augmentation of 67.5% was observed for 0.5 mass% MWCNT/ distilled water nanofluids followed by 59.8% for hybrid Ag-MWCNT/distilled water nanofluids, and the least enhancement of 52.1% was observed with Ag/distilled water nanofluids for Reynolds number 2200. The hybrid nanofluids showed better enhancement compared to silver nanofluids. The heat transfer showed an increase with Reynolds number and particle loading. New correlations were developed for the nanofluids for heat transfer enhancement. Keywords Nanofluids · Characterization · Silver · Multiwalled carbon nanotubes · Heat transfer coefficient · Hybrid nanofluids
Introduction The cooling efficiency of thermal equipments can be increased by the use of active and passive methods [1]. The active methods, like stirring mechanical aid, surface * Vinay Singh [email protected] Munish Gupta [email protected] Sandeep Kumar [email protected] Neeraj Dilbaghi [email protected] 1
Department of Mechanical Engineering, Guru Jambheshwar University of Science and Technology, Hisar 125001, Haryana, India
2
Department of Mechanical Engineering, JaganNath University, Bahadurgarh – Jhajjar, Delhi NCR, Haryana, India
3
Department of Bio and Nano Technology, Guru Jambheshwar University of Science and Technology, Hisar, Haryana 125001, India
vibrations, electrostatic fields, jet impingement and spray, need external power input for heat transfer enhancement, whereas the passive methods induce heat augmentation by surface modification using inserts, coiled/twisted tapes, rough surfaces, etc. No external power is required in passive methods. After exploring these methods of heat transfer, researchers focused the research on improving the thermophysical properties of fluids used for heat transfer enhancement. It was found that just like a new type of solid/liquid suspension which improves the thermophysical properties, nanofluids improve the thermal conductivity of the bulk fluids to the highest degree and also possess better suspension stability and mobility in comparison with the conventionally used millimetric
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