HEAT AERODYNAMIC EFFICIENCY OF HEATING SURFACES FOR COOLING OF ELECTRONIC DEVICE ELEMENTS

Abstract


 
 
 In the article a comparative analysis of the thermal aerodynamic efficiency of small-sized heat-exchange surfaces (radiators) with different types of fins under conditions of forced convection is carried out. In this article are descried surfaces with plate finning, plate-split finning, needle-pin finning and mesh-wire. The compared surfaces have approximately the same overall dimensions, the fins are placed on a flat basis with a size of 70x70 mm, and the height of the fins is 35 mm. The dissipated thermal power and cooling flow velocity vary, respectively,
 
 
 
 from 20 to 80 W and from 1,5 to 10 m/s, and the aerodynamic drag change from 5 to 75 Pa. Surfaces with plate and plate-cut fins with step between fins 6,9 mm; 5,0 mm; 2,5 mm, fin thickness 1,4 mm; 0,55mm, cutting depth of the fin 14 mm; 21 mm; 28mm and the angles of rotation of the sections of edges to the incoming stream 30° and 45° were investigated. The following performance criteria are used: surface overheating temperature relative to the ambient temperature and complex parameter αпр·Y, which takes into account the geometric and thermo physical characteristics of the surfaces. Comparative analysis showed that incomplete cutting of the plate fins and rotation of their parts at a certain angle to the cooling flow leads to an increase in thermodynamic efficiency. The highest thermal efficiency among the plate-cut surfaces is the surface with relative cutting depth hc/h = 0,6, without rotation of the sections of edges (j = 0 °), the step between the edges s = 2,5 mm and the thickness of the edges δ = 0,55 mm. Its efficiency is (20 - 35) % higher than that of a smooth-finned surface with parameters hc/h = 0; j= 0, s = 2,5 mm, δ = 0,55 mm. Compared to plate-cut surfaces having other finning parameters, their efficiency is on average higher by (50 - 65) %. The needle-surface surface is slightly higher than the plate-fined surface with s = 6,9 mm, δ = 1,4 mm and s = 5,0 mm, δ = 0,55 mm, however, lower by (15 - 25) % plate- cutting surfaces having an intercostal step of 6,9 mm and 5,0 mm, fin thicknesses of 1,4 mm and 0,55 mm, angles of rotation 30°, 45° and depth of cut 14 mm; 21 mm; 28 mm. The worst results in thermodynamic efficiency showed a mesh surface.