HEAT TRANSFER ENHANCEMENT IN SHORT RECTANGULAR CHANNELS WITH TRANSVERSE PROJECTIONS AND GROOVES

This Report is dedicated to systematic experimental investigation's results of heat transfer enhancement when air flow is going through short rectangular channels with smoothly rounded two-dimensional surfaces, which have transverse projections and grooves. These experimental investigations have been carried out using experimental tubular-plate water-air radiator constructions. For these purposes, there were designed and manufactured 12 standard air heat transfer surface design sizes. They were designed for following defining geometrical dimension parameter ranges: l'/d = 0.27 - 2.0 и d*/d = 0.72 - 0.93. Experimental investigation's results analysis had shown that rational heat transfer enhancement process was realised under condition (Nu/Nu_sm)_Re=idem / (ξ/ξ_sm)_Re=idem ≥ 1 in investigated channel constructions. This analysis have detected that geometrical dimensionless heat exchange channel l'/d и d*/d parameters changes can control rational heat transfer enhancement process. The heat transfer enhancement level for the beginning section of the channel, in this case, is somewhat lower in comparison with long channels. Nevertheless, with others conditions being equal, these obtained results allowed to reduce tubular-plate water radiator (equipped with smooth cooling plates) core's volume and mass up to 1,25 -1.5 times.