Pressure Effects on the Counting Efficiency of a Commercial Condensation Nucleus Counter
The CASL/UMR has been heavily involved in the measurement of combustion particles in the plumes of jet aircraft. Intrinsic to this determination is the operating efficiency of our condensation nucleus counters (CNCs) under the varying conditions encountered during flight. At 30-40 kft altitude, ambient pressures can reach 0.2 atm. The efficiency of a CNC for samples at this pressure was found to drop off to approximately 10% from its sea-level operating efficiency. Thermodynamic considerations reveal that a grouping of independent parameters (pressure, flow rate through the CNC, physical dimensions of the counter's saturator, etc.) control the efficiency of the device. For example, one particular commercial CNC was found to have an optimum operating efficiency at 1.5 times the factory-recommended flow rate of 1.4 L/min at reduced pressures, a flow of 2.2 L/min actually doubles the counter's efficiency at 35 kft.
M. R. Wilson et al., "Pressure Effects on the Counting Efficiency of a Commercial Condensation Nucleus Counter," Transactions of the Missouri Academy of Science, vol. 31, pp. 55, Apr 1997.
Missouri Academy of Science meeting, (1997: Apr., Warrensburg, MO)
Article - Conference proceedings
© 1997 The Authors, All rights reserved.
01 Apr 1997