The Effect of Dissolved Air on the Cooling Performance of a Partially-Confined FC-72 Spray
Abstract (Summary)The objective of this thesis is to investigate the heat transfer performance of a partially-confined FC-72 spray with varying dissolved air concentrations. An experimental test rig consisting of a spray chamber coupled to a fluid delivery loop system was used to obtain temperature, pressure, and critical heat flux (CHF) data. A downward facing nozzle within the spray chamber allowed the FC-72 fluid to be sprayed onto an upward facing, thick-film, resistor heater. The heater was mounted onto a glass post, with a sump system to allow removal of excess fluid. Type-E thermocouples were imbedded in the post to obtain temperature data. The parametric ranges for experimental testing were as follows: volume-percent concentration of dissolved air, 5 ? Cm ? 18%, chamber pressure, 6.90x10^4 ? Pch ? 8.27x10^4 N/m^2 (10 ? Pch ? 12 psia), subcooling, 2 ? Tsc ? 12°C, volumetric flow rate, 6.31 ? V ? 10.5 cm^3/s (6.0 ? V ? 10.0 gph). Test data were obtained for comparison of CHF with varying C while controlling the spray chamber pressure. No significant variation in heat transfer performance was observed. The applicability of Henry's law to the current system was investigated, and air concentration measurements using Henry's law were compared with those obtained using a direct sample method. The resulting air concentration measurements did not agree. An empirical mathematical relationship allowing for determination of surface heat flux with varying flow rate was also developed. The relationship was obtained using test data at flow rates of V = 6.31, 8.41, and 10.5 cm^3/s (6.0, 8.0, and 10.0 gph), and was validated using experimental data obtained for flow rates of V = 7.36 and 9.46 cm^3/s (7.0 and 9.0 gph).
School:Wright State University
School Location:USA - Ohio
Source Type:Master's Thesis
Date of Publication:01/01/2008