Experimental and theoretical investigation of micro pin fins heat exchanger used in convective cooling application

الملخص EN

Experimental and theoretical investigations of flow and thermal performance of an annular pin fin heat exchangers exposed to constant heat flux have been preformed.

A special test rig was designed and built for this purpose.

The main test section is an annulus of radius ratio (0.85) containing 10 rows of 1mm diameter pins with 5 pins in each row.

The range of cooling air Reynolds number based on the hydraulic diameter of the channel, is (6774 to 11120).

In the Theoretical part the well known Fluent (6.3) package was used for solving the governing equations for flow and Energy equation for heat transfer with RNG k-ε turbulence model.

Results showed that the pin fins enhanced the heat transfer by a factor of (1.31 to 1.42) and increased the friction factor by (3 to 4) times compared to the one obtained for smooth annular channel without pins.

A Nusselt-Reynolds correlation was obtained from the experimental data valid in the Reynolds number range studied.

Reasonable agreement between the experimental and theoretical results was obtained with average difference (5 %) over the Reynolds number range.

The overall thermal performance obtained was larger than (1).