Effects of Curved Ribs on Heat Transfer, Friction and Exergy Loss in Rectangular Cooling Channels by CFD

Abstract

In the present work, the effects of radii ratios of curved rib on heat transfer performance, friction factor, thermal performance factor and exergy loss in roughened duct are investigated. The curved ribs are formed in concave and convex shapes, with and without cut. Reynolds number values are varied in the range of 5000 to 30,000, which were most suitable for roughened duct. The radii ratios of curved rib are studied with values of (2, 3 and 4), and the effects are discussed and compared with the transverse straight rib (R00). The results show that the heat transfer enhances by using a convex broken rib at different radii ratios. The curved rib with a radius ratio of 2 offers the best heat transfer characteristics and exergy loss compared with the other cases. Convex broken rib (case D) shows the highest thermal performance factor compared with the other investigated cases. Case D shows a good improvement in heat transfer with lower pumping power consumption compared with the other investigations.

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Abbreviations

Q :

Heat transfer rate (W)

q :

Heat flux (W/m2)

\( \dot{m} \) :

Mass flow rate Kg/s

\( \dot{W} \) :

Work kW

\( \dot{E} \) :

Exergy rate kW

\( I \) :

Specific enthalpy (kJ/kg)

\( \dot{\sigma } \) :

Exergy destruction rate (irreversibility) kW

A:

Area (m2)

D:

Diameter (m)

E :

Energy kW

FR:

Friction factor ratio (−)

h:

Heat transfer coefficient (W/m2 K)

I:

Enthalpy (J/kg)

L:

Heated wall length (m)

p :

Static pressure (Pa)

R :

Radius (-)

R * :

Radii ratio (R/Dh) (-)

Re :

Reynolds number, ud/ν (-)

s:

Specific entropy kJ/kg

T:

Temperature (K)

TPF:

Thermal performance factor

u :

Velocity (m/s)

HTC:

Heat transfer coefficient

R00:

Rib 90°

\( \rho \) :

Density (kg/m3)

∆:

Difference

av:

Average

b :

Bulk temperature

h :

Hydraulic

w :

Wall temperature

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Correspondence to Antar M. M. Abdala.

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Elwekeel, F.N.M., Abdala, A.M.M. & Zheng, Q. Effects of Curved Ribs on Heat Transfer, Friction and Exergy Loss in Rectangular Cooling Channels by CFD. Iran J Sci Technol Trans Mech Eng (2020). https://doi.org/10.1007/s40997-020-00376-3

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Keywords

  • Heat transfer
  • Exergy loss
  • Curved rib
  • Internal cooling
  • CFD