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This study examines the heat transfer enhancement from a horizontal rectangular fin embedded with triangular perforations (their bases parallel and toward the fin tip) under natural convection. The fin's heat dissipation rate is compared to that of an equivalent solid one. The parameters considered are geometrical dimensions and thermal properties of the fin and the perforations. The gain in the heat transfer enhancement and the fin weight reduction due to the perforations are considered. The study shows that the heat dissipation from the perforated fin for a certain range of triangular perforation dimensions and spaces between perforations result in improvement in the heat transfer over the equivalent solid fin. The heat transfer enhancement of the perforated fin increases as the fin thermal conductivity and its thickness are increased.

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Heat transfer dissipation from a horizontal rectangular fin embedded with equilateral triangular perforations is computed numerically using one-dimensional finite element technique. The bases of the triangles are parallel and toward the fin base. The body of the fin is discretized into a number of subdivisions (finite elements). The number of these elements can be altered as required according to the automatic mesh generation. The heat dissipation of the perforated fin is computed and compared with that of the solid one of the same dimensions and same thermal properties. The comparison refers to acceptable results and heat dissipation enhancement due to certain perforation.Keywords Finite element · Perforated fin · Heat dissipation · Heat transfer enhancement List of symbolsA cross sectional area of the solid fin (m 2 ) A c cross sectional area of the triangle perforation (m 2 ) A e cross sectional area of the finite element (m 2 ) A pc area of the inner surface of the perforation (m 2 ) A ps area of the perforated surface of the fin (m 2 ) b triangle perforation dimension (m) h heat transfer coefficient (W/m 2• C) h pc heat transfer coefficient of the inner surface of the perforation (W/m 2• C) h ps heat transfer coefficient of the perforated surface of the fin (W/m 2 • C) h s heat transfer coefficient of surface of the two sides of the fin (W/m 2 • C) h t heat transfer coefficient of the fin tip (W/m 2 • C) k thermal conductivity of fin material (W/m • C) L fin length (m) l vector unit (m) Le finite element length (m) N number of perforations P fin perimeter (m) Pe finite element perimeter (m)742 A. H. M. AlEssa Q fin heat dissipation rate (W) RQF ratio of heat dissipation rate of perforated fin to that of non-perforated (solid) one S perforation spacing (m) t fin thickness (m) Ve finite element volume (m 3 ) W fin width (m)

The present work aimed to examine the performance of a thermoelectric generator (TEG) augmented with a hydronic evacuated tube solar collector heat exchanger used to heat a cold zone. TEGs were operated on the temperature difference between hot water circulated through the heat exchanger and the cold temperature of the surrounding space. The setup model of a heat exchanger with TEGs installed on the outer surface was examined numerically under steady state conditions for natural and forced convection modes. The results obtained show that 1.03 W of electricity could be produced when the temperature differences across the TEG and air velocity are 60 °C and 0.5 m/s, respectively. Also, an increase of 17.47% of TEG power was achieved for each 5 °C drop in surrounding space temperature and by 11% for each 5 °C rise in circulated hot water temperature. Besides the importance of improving TEG efficiencies, the amount of generated electricity may be valuable when large-surface area heat exchanger units are installed in large systems.