Mini- and Microchannels can be attractive for some cooling applications, since the small hydraulic diameters lead to high heat transfer coefficients and enable a compact design. Such properties are required for the cooling of the structures of the IFMIF High Flux Test Module, which is being developed at INR. In this device, low pressure helium is chosen as cooling gas, flowing through narrow coolant channels of 1mm x 25mm cross section. These coolant flows are characterized by transitional Reynolds numbers (3000 < Re < 12000), intensive heating (0.001 < q+ < 0.003) and dominant entrance effects, due to the short channel lengths (l/dh < 60).
|Cross section through 1 of 8 parallel HFTM compartments containing three irradiation rigs, showing the cooling minichannels (white) and insulation gaps (violet)|