CFDC-IAS - Handix Scientific Inc.

CFDC-IAS

Continuous Flow Diffusion Chamber - Ice Activation Spectrometer

Purpose

The Continuous Flow Diffusion Chamber - Ice Activation Spectrometer (CFDC-IAS) measures ice nucleating particle (INP) concentrations in real- time. Based on Colorado State University’s design that has a long and successful track record of INP measurements, the CFDC-IAS adds a number
of automation features to enable autonomous and reliable long-term operation in the laboratory or field.

CFDC-IAS shown in a laboratory without insulation on the processing chamber to show cooling lines and other chamber details. Sample aerosol are dried (not shown) and sampled into the top of the processing chamber (right), where they are exposed to user-controlled temperature and relative humidity conditions. INP form ice crystals that are detected optically at the base of the chamber.

Applications:

Laboratory INP characterization
Field ambient INP measurement
Aerosol-cloud interactions
Climate research
Weather modification and cloud seeding

INP measured during a 24-hour period in Beijing by a CFDC-IAS operating autonomously. The CFDC-IAS operated for approximately 6 weeks with minimal user intervention before being relocated to a new site in late June 2018. Gaps in INP data result from melting and re- icing measurement chamber to maintain sensitivity.

Features

Cylindrical processing chamber to minimize edge-effects
Measurement range approximately -10 to -40 C and RH 80-108%.
Liquid-based refrigeration system provides excel- lent temperature stability and uniformity
Approximately 1 L-1 measurement sensitivity

Specifications

Operating Principle

The CFDC-IAS exposes sampled aerosol particles to controlled temperature and water saturation conditions found in mixed-phase clouds. It features two ice-coated cylindrical copper walls that are kept at different temperatures to drive temperature and water vapor pressure gradients between them. The different rates of diffusion for water vapor and heat lead to a region between the walls that is super-saturated with respect to ice, and depending on the magnitude of the gradient, water. Aerosol passing between the walls freeze either directly as ice crystals (deposition freezing) or first activate as a super-cooled liquid droplet, which may then freeze (condensation/immersion freezing). Ice crystals formed in the chamber are counted with an optical particle counter at the exit of the chamber.

Simplified diagram of the CFDC-IAS measurement chamber showing concentric arrangement of ice-covered cold inner and warm outer walls (left) and cartoon showing growth of droplets and ice crystals in different sections of the chamber (right). Only large crystals and small aerosols reach the OPC.

Petters, M. D., et al., Ice nuclei emissions from biomass burning, Journal of Geophysical Research, doi:10.10292008JD011532, 2015.

Bi, K., et al., Continuous measurements of ice nucleating particles in Beijing, China, submitted to Geophysical Research Letters, 2018.

Reference:

Particle Size Range	Depends on upstream impactor, usually 1-2.5 μm
Sensitivity and Range	1-sigma limit of detection at 300 s; 1 L-1
Flow and Response Time	Sample flow: 1.5 LPM Response time: ~3-5 minutes
Environmental Operating Conditions	Min. Temperature 5 C Max. Temperature 30 C Ambient Humidity: non-condensing
Data Logging and Storage	Stores data on integrated control and acquisition PC with 2 TB storage, sufficient for many months.
Required Consumables	Purge gas: Nitrogen @ 15 PSI Icing liquid: DI water (~4 L) Cooling liquid: ethanol (~12 L)
Power Requirements	AC power: 110-230 VAC, 50/60 Hz Average power consumption 6000 W (peak)
Communications	Ethernet Interface: 8-wire, RJ-45, 10/100 BASE-T, TCP/IP
Physical Dimensions	Instrument. 26 x 50 x 60 in Weight ~225 kg

Specifications subject to change without notice.

Particle Size Range

Depends on upstream impactor, usually 1-2.5 μm

Sensitivity and Range

1-sigma limit of detection at 300 s; 1 L-1

Flow and Response Time

Sample flow: 1.5 LPM Response time: ~3-5 minutes

Environmental Operating Conditions

Min. Temperature 5 C Max. Temperature 30 C Ambient Humidity: non-condensing

Data Logging and Storage

Stores data on integrated control and acquisition PC with 2 TB storage, sufficient for many months.

Required Consumables

Purge gas: Nitrogen @ 15 PSI Icing liquid: DI water (~4 L) Cooling liquid: ethanol (~12 L)

Power Requirements

AC power: 110-230 VAC, 50/60 Hz Average power consumption 6000 W (peak)

Communications

Ethernet Interface: 8-wire, RJ-45, 10/100 BASE-T, TCP/IP

Physical Dimensions

Instrument. 26 x 50 x 60 in Weight ~225 kg

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Sample flow: 1.5 LPM
Response time: ~3-5 minutes

Min. Temperature 5 C
Max. Temperature 30 C
Ambient Humidity: non-condensing

Purge gas: Nitrogen @ 15 PSI
Icing liquid: DI water (~4 L)
Cooling liquid: ethanol (~12 L)

AC power: 110-230 VAC, 50/60 Hz
Average power consumption 6000 W (peak)

Instrument. 26 x 50 x 60 in
Weight ~225 kg