Study on crisis of heat transfer and hydraulic resistance in a rod assembly with heat transfer intensifiers

An experimental study has been made of the heat emission and the hydraulic resistance in the rod assembly with heat exchange intensifiers. These experiments have been conducted with an assembly of 18 heated tubes with a diameter 13.6x0.2 mm, which make a triangular and square pattern with a step of 16 mm inside the round channel of the 80 mm diameter. Three types of intensifiers have been studied as follows: the intensifiers with an overcontraction of the clear cross-section, the intensifiers with a twist of the flow and the intensifiers with passing the flow of the coolant into narrow gaps. The heat emission crisis has been studied under the pressure of 74 bar and the mass velocity of 1000 - 1500 kg/sq.ms. The intensifiers having been studied permit to increase the critical density of the heat flux by 25 - 60 per cent, increasing at the same time the hydraulic resistance by 160 - 300 per cent