Heat Transfer and Entropy Generation Abilities of MWCNTs/GNPs Hybrid Nanofluids in Microtubes

Abstract

Massive improvements in the thermophysical properties of nanofluids over conventional fluids have led to the rapid evolution of using multiwalled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs) in the field of heat transfer. In this study, the heat transfer and entropy generation abilities of MWCNTs/GNPs hybrid nanofluids were explored. Experiments on forced convective flow through a brass microtube with 300 µm inner diameter and 0.27 m in length were performed under uniform heat flux. MWCNTs/GNPs hybrid nanofluids were developed by adding 0.035 wt.% GNPs to MWCNTs water-based nanofluids with mass fractions of 0.075–0.125 wt.%. The range of the Reynolds number in this experiment was maintained at Re = 200–500. Results showed that the conventional approach for predicting the heat transfer coefficient was applicable for microtubes. The heat transfer coefficient increased markedly with the use of MWCNTs and MWCNTs/GNPs nanofluids, with increased pressure dropping by 12.4%. Results further showed a reduction by 37.5% in the total entropy generation rate in microtubes for hybrid nanofluids. Overall, MWCNTs/GNPs hybrid nanofluids can be used as alternative fluids in cooling systems for thermal applications.

Fluid Flow and Entropy Generation Analysis of Al2O3–Water Nanofluid in Microchannel Plate Fin Heat Sinks

“…Figure 9 demonstrates the comparison of the Fanning friction factor between the current results and the available experimental results from Karimzadehkhouei et al [ 66 ], Hussien et al [ 68 ], Jung et al [ 80 ], Lee and Mudawar [ 81 ], Ho et al [ 82 ], Hussien et al [ 83 ], and Peyghambarzadeh et al [ 84 ]. It is observed that our results agree favorably with the experimental data reported by Karimzadehkhouei et al [ 66 ], Lee and Mudawar [ 81 ], Ho et al [ 82 ], and Hussien et al [ 83 ], and our results are close to the available analytical data from Duan and Muzychka [ 76 ].…”

“…Entropy generation minimization [ 52 , 53 ] and the principle of least action [ 54 , 55 , 56 ] are two important methods to study the performance optimization of a thermal system. Some efforts have been made to research into the entropy generation of different thermal systems [ 23 , 37 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 , 67 , 68 ]. Khan et al [ 59 ] studied the performance of MCHS using an entropy generation minimization procedure, and proposed a general expression evaluating irreversibilities.…”

Assessment of Existing Photovoltaic System with Cooling and Cleaning System: Case Study at Al-Khobar City

“…Finally, it should be reported here that there is extensive work has been done in order to enhance the efficiency of the Photovoltaic (PV) or the hybrid Photovoltaic/Thermal (PV/T) systems by dispersing the nano solid particles into the main base fluid. [22,23]. Authors will extend the work to include these technologies in the near future.…”

A Brief Survey of Preparation and Heat Transfer Enhancement of Hybrid Nanofluids

“…Recently, Hussien et al [58] to [60] studied the thermal performance of MWCNTs/water nanofluid and MWCNTs/GNPs hybrid nanofluid in minitubes. Their experimental results show high enhancement of heat transfer coefficients with an increase in pressure drop when using a low weight concentration of MWCNTs/GNPs.…”