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|Title:||Flow Boiling Heat Transfer in a Long, Small Diameter, Vertically Oriented, Uniformly Heated Tube|
|Authors:||Statham, Allan Bradley|
|Keywords:||Engineering Physics;Engineering Physics|
|Abstract:||<p>A thermalhydraulics experiment was constructed at McMaster University that is capable of measuring heat transfer data for test sections up to 1 m long at pressures up to 10.0 MPa. The test section was powered by a 96 kW DC power supply with digital control. Inlet temperature was controlled using a 40 kW RMS AC welding power supply. The experiment was pressurized using a 3.79 L bladdertype accumulator charged by a 13.8 MPa nitrogen cylinder and controlled using Swagelok pressure-reducing and back-pressure regulators. Up to 870 kPa of pump head was supplied using a Micropump GC-M25 pump.</p> <p>Commissioning data was gathered using a 93.2 cm long by 4.6 mm inside diameter Inconel 600 test section at 2.0 MPa with inlet temperatures from 126-180°C, representing inlet qualities of -0.2 to -0.08, and mass fluxes of 1500 and 2000 kg m<sup>-2</sup> S<sup>-1</sup>. Maximum outlet quality was 0.07. Heat transfer was measured using electrically isolated thermocouples 2, 4, 9, 14, 24, 34, and 44 cm from the test section outlet. Using the most reliable thermocouple 4 cm from the test section outlet, and including only data that had a heat balance error of less than ±2%, the PetukhovPopov and Gnielinski correlations for single phase heat transfer overpredicted experimental results with mean errors of 10.2% and 19.1% and standard deviations of ±3.0% and ±3.3% respectively. Several sub cooled boiling correlations showed good predictive capability for the present results. The Thom correlation predicted subcooled boiling heat transfer 4 cm from the test section outlet particularly well with a mean error of 0.5% and a standard deviation of ±14.1%. Low mass quality saturated boiling data was predicted with a mean error of 15.3% and a standard deviation of 18.0% by the modified Chen correlation. Overall the preliminary results show good quantitative agreement with existing correlations. More data will be gathered in the near future to corroborate these results and verify the experimental capabilities at a wider range of pressures and flow rates.</p> <p>The experiment will be used in the future to gather transient critical heat flux data. The experimental measurement accuracy, measurement speed, maximum inlet temperature, and flow control will be improved. This will be achieved by improving the thermocouple shielding and isolation, modifying and adding new data acquisition instrumentation, adding a heat exchanger at the test section outlet for inlet preheating, and adding an electronically controlled variac to control the pump voltage.</p>|
|Appears in Collections:||Open Access Dissertations and Theses|
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