Cleanrooms: Two promising research areas William Tschudi – LBNL Peter Rumsey – Rumsey Engineers November 4, 2004
Jan 13, 2016
Cleanrooms: Two promising research areas
William Tschudi – LBNLPeter Rumsey – Rumsey Engineers
November 4, 2004
Two promising research areas
Demand controlled filtration
Fan-filter unit energy performance
Demand controlled filtration
The goal: Match airflow to cleanliness. Through real-time monitoring of cleanliness in the cleanroom, allow lower airflow unless excessive numbers of particles are detected. If particle counters record increased particulates, airflow is automatically increased through variable speed drives on recirculation fans.
Demand controlled filtration – pilot study
Pilot study in LBNL cleanroom confirmed feasibility
Particle sizes of concern were studied
Fan speed controlled by particle counts
Optimum airflow is not too high or too low
Location and numbers of particle counters need additional study
Demand controlled filtration – demonstrations
LBNL is planning a demonstration to use the concept in an operating industrial cleanroom
Cornell University will be demonstrating the concept in its new Duffield Hall cleanroom
Demand controlled filtration – other options
Turndown of airflow can be achieved through simple controls:
Manual Timers Occupancy sensors Combinations of these
An informal survey of the ASHRAE TC 9.11 committee (cleanspaces) found a that number of cleanrooms are currently turning down airflow
Fan-filter units
The Need: A standard method of testing and reporting performance so that owners and designers can select units based upon performance – not hype. Performance can include: energy use, noise, vibration, filtration effectiveness, etc.
The players
Industrial Technology Research Institute (ITRI) Institute of Environmental Sciences and
Technology (IEST) Air Movement and Control Association
International (AMCA) SEMATECH International FFU manufacturers and end users CA Energy Commission and public utility
companies
FFU’s are popular
Fan-filter units are increasingly specified in cleanrooms in various industries
Fan-filter units are used in mini-environments
Many manufacturers produce fan-filter units for use in cleanrooms
Why the need for standardized reporting?
Benchmarking and testing in Taiwan has shown wide variations in performance
Fan-Filter manufacturers report performance in different ways
Cleanroom Owners and Designers need a standard comparison
Incentive programs need a baseline and standard comparison
Serious cost and energy efficiency implications
11
Recirculation systems
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
11000
Fac. AClass 10 Press.Plen.
Fac. AClass 100
Press.Plen.
Fac. B.1Class 100
Ducted
Fac. B.1Class 100
FFU
Fac. B.2Class 100
Ducted
Fac. B.2Class 100
FFU
Fac. CClass 100
Press.Plen.
Fac. DClass 10Ducted
Fac. EClass 100
FFU
Fac. EClass 100
Press.Plen.
Fac. FClass 10Press.Plen.
Fac. FClass 10Press.Plen.
Fac. FClass 10Press.Plen.
Fac. FClass 10k
CFM / kW (higher is better)
Averages (cfm / kW)FFU: 1664
Ducted: 1733Pressurized Plenum: 5152
Recirculation Efficiencies
0
500
1000
1500
2000
2500
3000
3500
4000
1 2 3 4 5 6 7 8 9 10 11 12 13 14
Facility
CFM/kW
Average 3440
Average 1953
LBNL Data
Sematech Data
Comparing fan-Filter units
If fan-filters are desired, how can their energy efficiency be determined?
Confusing claims and catalogue information:
Watts/fpm Noise (dBA @ distance)
for single unit vs. many External static Flow area
Fan Filter Units' CFM/kW at .8"w.g. system pressure
0
1000
2000
3000
4000
5000
6000
7000
Mgf. 1 Mfg. 2 Mfg.3 Mfg. 4 Mfg. 5
CFM/kW
FFU energy efficiency
Source: Rumsey Engineers
Taiwan test data
Test procedure development
LBNL has developed a draft test procedure addressing energy performance
Draft procedure available on LBNL website – comments welcome
Test procedure considerations Available total pressure
Air flow Quantity/Variable flow
Uniformity
Sensible cooling (if provided)
Total power consumption
Noise and vibration levels
Filter area
Size of FFU (2’ x 4’, 4’ x 4’, etc.)
Test arrangements
Similar to testing large fans
Discharge
Pressure Tube
Damper
FFU Being Tested
Booster FanSettling Screens Nozzles
Establishing a baseline
PG&E is sponsoring a test of the test procedure at their test facility
CA Energy Commission Public Interest Energy Research (PIER) is sponsoring testing to establish baseline
If you can loan units for testing let us know
Expected outcomes
An IEST recommended practice will be issued
CA public utilities will establish baseline and include in incentive programs
Owners and designers will have a standard way to compare performance
Owners can evaluate first cost vs operating cost
Improvement in performance will follow
Energy-efficient Fan-filter Units
Design Considerations Contour of inlet airflow path Baffles to direct flow and deaden sound Motor efficiency – AC or DC Fan efficiency Clearances Filter media Depth of box Filter area Controls
More efficient units have considered all of this
Questions?
Thank you!
http://hightech.lbl.gov