ARTICLE:

• HEAT TRANSFER AND PRESSURE LOSS CHARACTERISTICS OF OBLIQUELY-ARRANGED CUT-FINS  download article

K. Tatsumi
Osaka Prefecture University, Sakai, Osaka, Japan

M. Yamaguchi
Osaka Prefecture University, Sakai, Osaka, Japan

Y. Nishio
Osaka Prefecture University, Sakai, Osaka, Japan

K. Nakabe
Osaka Prefecture University, Sakai, Osaka, Japan

ABSTRACT

Notches have been applied to a parallel fin array, referred to as “cut-fin”, for the purpose of enhancing the fluid mixing and heat transfer, and also reducing the pressure loss penalty. To evaluate the effects of the notch size, the notch arrangement and the spanwise fin-pitch on the heat transfer and pressure loss characteristics, experimental and numerical studies were carried out for a channel with cut-fins mounted on the bottom wall. Velocity fields were measured by the PIV system and heat transfer coefficients were obtained by applying the modified single-blow method. Three-dimensional numerical simulation was conducted to calculate the flow and thermal fields including the heat conduction inside the fin. In the first half of this paper, the results of the preliminary test cases of parallel plates and cut-fin arrays are introduced to evaluate the experimental setup and numerical code. In the test case, an excellent agreement was obtained between the numerical and experimental results.
In the case of cut-fin array arranged in parallel, although the heat transfer surface area is reduced, a comparable heat transfer performance to the notch-less plain-fin case is obtained. The notch size does not largely affect the overall heat transfer performance due to the existence of the trade-off problem between the increase of the heat transfer coefficient and the decrease of the heat transfer area. Reduction of the friction loss is also achieved in this case indicating an increase of the total performance. An optimum value of the fin pitch exists for minimizing the fin thermal resistance and is smaller than that of the plain-fin case. When the notches are obliquely arranged, a larger heat transfer coefficient is obtained compared to the parallel arrangement case. This is believed to be attributed to the spanwise flow produced by the notch flowing along the inclined notch array.

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