Experimental Study of Heat Exchange and Aerodynamic and Thermal Contact Resistance of Staggered Bundles of Tubes with Spiral Rolled Fins of Air-Cooled Devices

Resumo

Results of a study of the thermal and dynamic characteristics of three types of six-row checkerboard bundles in a transverse flow in the interval of Reynolds number Re = (3−18) × 10³ are presented. The experimental data are generalized by similarity equations. The heat-exchange coefficients of each transverse row of the bundle are measured and features that arise in the variation of heat exchange by row of the bundle are identified. The mean value of the thermal contact resistance in the range of variation of the temperature of the contact surfaces 79−95°С is found to be equal to 2.13·10^{− 4} m²·K/W. On the basis of results of the study it is shown that the use of an equilateral configuration of tubes in bundles should be rejected and replaced by an isosceles configuration with steps S₁ = 68−69 mm and S₂ = 55.4 mm, a configuration that is advantageous in terms of energy and on the basis of a cost-benefit analysis.