Heat transfer enhancement in a square channel with a set of triangular prisms: an experimental study

ABSTRACT

In this study, heat transfer behavior in a channel adapted with a set of equilateral triangular prisms was investigated experimentally in a turbulent flow regime, with a range of Reynolds numbers corresponding to 1x10⁴<Re<8x10⁴. The cross-section of the channel is square, and the triangular prisms were installed in the middle of the channel. In the test section of the channel, only the bottom wall was heated with constant heat flux. The square channel geometry and the triangular obstacle dimensions were assumed as fixed. Multiple equilateral triangular prisms were used with three different tandem arrangements and four different attack angles in the cross-flow of air. The heated wall temperatures, and channel inlet and outlet temperatures were measured using thermocouples on the test section. The triangular prisms changes flow structure in the flow field by cross-flow interaction, and increases the heat transfer from the heated surface. It was observed that compared to the smooth channel, the heat transfer was enhanced by about 22% for a single triangular prism. The obtained results are given as dimensionless parameters and discussed in this study. Results are compared with the existing literature and show strong similarities. Overall, in our study, triangular prisms showed a more noticeable increase in heat transfer for channel flows.

KEYWORDS:

• Triangular prism
• cross-flow
• heat transfer enhancement

Nomenclature

a side length of the triangle

b height of the triangle

c specific heat

d triangular edge length

D_h hydraulic diameter

f friction factor

H channel height

k conductivity

h heat transfer coefficient

L heated wall length

NuNusselt number

ΔP pressure difference

Pr Prandtl number

$\mathit{q}{ }^{\mathrm{\prime \prime }}$ heat flux

Re Reynolds number

ρ fluid density

T_b bulk temperature

T_w wall temperature

u velocity

$U_{\mathrm{\infty }}$ average inlet velocity

η performance factor

Acknowledgments

The authors gratefully thank ASÜ-BAP (Scientific Research Project Unit of Aksaray University) for its financial support under contract: ASÜ BAP-2018-013.

Disclosure statement

The authors declare that there is no financial, personal, or competing interest in this paper.