3. DESCRIPTION OF TEST FACILITY
Water was heated to the desired temperature via a preheater with the flow monitored by turbine flow meters. The vertically mounted test section consisted of a 920mm long Nimonic 75 tube, 9.85mm ID and 14.0mm OD, which was surrounded by five concentric layers of polished nickel and 50mm of insulation to act as a heat shield and minimise heat losses. Two 36mm thick nickel-plated copper blocks were brazed to either end of the heated length, which acted as the hot patches. The position of the dry-out front was maintained upstream of the test section by heat transfer from the hot patches, which were instrumented with thermocouples to enable the heat fluxes to be evaluated, although only upflow tests (using the lower hot patch) were performed in this facility. The test section itself had a total of 39 thermocouples attached to the outer surface.