Second law analysis for nanofluid flow in mini-channel heat sink with finned surface: a study on fin geometries

  • Mostafa Azadi
  • Elham Hosseinirad
  • Faramarz HormoziEmail author
  • Saman Rashidi


In this numerical work, a second law analysis is carried out for the nanofluid flow and heat transfer in the mini-channel with finned surface. The mini-fins with various geometries, including trapezoidal, square, triangular, and sinusoidal, are located on the bottom surface of the mini-channel. The effects of mini-fins geometry, mini-fins number, Reynolds number, and solid volume fraction of nanoparticles on the temperature and velocity distributions, frictional and thermal irreversibilities, and Bejan number inside the mini-channel are studied. The numerical method is validated with the experimental data. The results show that the sinusoidal, triangular, square, and trapezoidal mini-fins generate up to 66.23%, 61.87%, 59.21%, and 57.80%, respectively, lower thermal irreversibility as compared with the smooth mini-channel. Among mini-fin geometries, the triangular mini-fins generate the maximum frictional irreversibility, while the trapezoidal mini-fins provide the minimum frictional irreversibility. The frictional irreversibility increases about 108.56%, while the thermal irreversibility decreases up to 46.33% as the mini-fin number increases from one to nine. The thermal irreversibility diminishes about 49% by boosting the Reynolds number from 100 to 500. Usage of nanofluid increases both frictional and thermal irreversibilities. Finally, the thermal irreversibility is a dominant term in the total irreversibility and the effects of frictional irreversibility can be ignored.


Second law analysis Mini-channel Mini-fin Nanofluid Geometry 

List of symbols


Surface (m2)


Bejan number (−)


Specific heat at constant pressure (J kg−1 K−1)


Hydraulic diameter of mini-channel (m)


Friction factor (−)


Heat transfer coefficient (W m −2 K  −1)


Fin height (mm)


Mini-channel width (mm)


Thickness of bottom wall in mini-channel (mm)


Thermal conductivity of fluid (W m−1 K−1)


Mini-channel length (mm)


Constant number (−)


Nusselt number (−)


Pressure (Pa)


Performance evaluation criteria (−)


Heat flux (W m−2)


Reynolds number (−)


Distance between two mini-fins (mm)


Irreversibility rate (W m−3 K−1)


Temperature (K)

u, v

Velocities (m s−1)


Fin width (mm)

x, y

Rectangular coordinate components (m)

Greek symbols


Dynamic viscosity (kg m−1 s−1)


Density of fluid (kg m−3)


Solid volume fraction of nanoparticles (−)





















Solid wall, smooth mini-channel







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Copyright information

© Akadémiai Kiadó, Budapest, Hungary 2019

Authors and Affiliations

  1. 1.Faculty of Chemical, Petroleum and Gas EngineeringSemnan UniversitySemnanIran
  2. 2.Department of Energy, Faculty of New Science and TechnologiesSemnan UniversitySemnanIran

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