Active Chilled Beam Technology

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Theory and fundamentals of Active Chilled Beams presented at the Illinois Chapter of ASHRAE, February 8, 2011. Presented by Matt Green of Thermosystems.

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Active Chilled Beam Technology

  1. 1. Presented by: Matt Green Active Chilled Beam Technology
  2. 2. <ul><li>Section I: Introduction to ACB Technology </li></ul><ul><ul><li>Types of Chilled Beams </li></ul></ul><ul><ul><li>ACB Technology Advantages </li></ul></ul><ul><ul><li>How ACB’s Work </li></ul></ul><ul><ul><li>How ACB Systems Compare to Other Systems </li></ul></ul><ul><ul><li>Common Applications of ACB Technology </li></ul></ul><ul><ul><li>Misapplications of ACB Technology </li></ul></ul><ul><li>Section II: ACB System Design Considerations </li></ul><ul><ul><li>DOAS/Airside System Design </li></ul></ul><ul><ul><li>Chilled Water System Design </li></ul></ul><ul><ul><li>Heating with ACB’s </li></ul></ul><ul><ul><li>Controlling ACB Systems </li></ul></ul><ul><ul><li>Condensation Prevention </li></ul></ul>Agenda
  3. 3. Section I: Introduction to ACB Technology Types of Chilled Beams
  4. 4. Section I: Introduction to ACB Technology Types of Chilled Beams – Active Chilled Beams <ul><li>Cooling and Heating </li></ul><ul><li>Fresh air supplied through beams </li></ul><ul><li>Very low acoustic signatures </li></ul><ul><li>Very high energy efficiency </li></ul><ul><li>Very high levels of occupant thermal comfort </li></ul>
  5. 5. ACB Technology Advantages <ul><li>Energy conservation </li></ul><ul><li>Reduced space consumption </li></ul><ul><li>Reduced maintenance costs </li></ul><ul><li>Increased comfort levels </li></ul>Section I: Introduction to ACB Technology
  6. 6. Section I: Introduction to ACB Technology How ACB’s Work <ul><li>A) Primary air duct connection (.3-1.2 in. w.c.) </li></ul><ul><li>B) Primary air plenum </li></ul><ul><li>Secondary air (room air) </li></ul><ul><li>Unit mounted coil (2-pipe or 4-pipe configuration) </li></ul>E) Mixed air (Induction ratio range 3:1 – 6:1) F) Discharge air (Cooling: 63-66ºF / Heating 75-85ºF) G) Adjustable mounting brackets
  7. 7. Section I: Introduction to ACB Technology How ACB Systems Compare to Other Systems - VAV <ul><li>First costs for ACB are typically higher than VAV: </li></ul><ul><ul><li>5-10% higher </li></ul></ul><ul><ul><li>Copper pipe largest cost ‘penalty’ for ACB systems </li></ul></ul><ul><ul><li>PEX piping, good alternative, save cost on branch piping insulation </li></ul></ul><ul><ul><li>DOAS/AHU & duct costs are lower in ACB systems </li></ul></ul><ul><li>ACB first costs are trending closer to VAV </li></ul><ul><li>Operating costs are significantly lower for ACB systems </li></ul><ul><ul><li>No Maintenance </li></ul></ul><ul><ul><li>Significant energy savings </li></ul></ul><ul><ul><ul><li>Reduction in AHU horsepower </li></ul></ul></ul><ul><ul><ul><li>Increased chiller EER </li></ul></ul></ul>Equipment VAV ACB DOAS/AHU and Fans $285,000 $185,000 Ductwork $260,000 $195,000 Chiller $150,000 $150,000 Copper Piping $55,000 $315,000 Active Chilled Beams $0 $110,000 VAV Units $75,000 $0 Sound Dampers $20,000 $5,000 Temperature Controls $105,000 $130,000 Registers and Diffusers $110,000 $40,000 Total $1,060,000 $1,130,000 Building Sq Footage 50,000 50,000 Cost/Sq Ft. $21 $23
  8. 8. Section I: Introduction to ACB Technology How ACB Systems Compare to Other Systems - FCU <ul><li>First costs for ACB are typically lower than FCU: </li></ul><ul><ul><li>5-10% lower </li></ul></ul><ul><ul><li>Savings on equipment and piping favor ACB systems </li></ul></ul><ul><li>Operating costs are significantly lower for ACB systems </li></ul><ul><ul><li>Fan energy savings </li></ul></ul><ul><ul><li>No maintenance </li></ul></ul><ul><ul><li>Significant energy savings </li></ul></ul><ul><ul><li>Chiller EER </li></ul></ul>Equipment FCU ACB DOAS and Fans $185,000 $185,000 Ductwork $170,000 $195,000 Chiller $150,000 $150,000 Copper Piping $420,000 $315,000 Active Chilled Beams $0 $110,000 Fan Coil Units $185,000 $0 Sound Dampers $5,000 $5,000 Temperature Controls $115,000 $130,000 Total $1,230,000 $1,090,000 Building Sq Footage 50,000 50,000 Cost/Sq Ft. $25 $22
  9. 9. Section I: Introduction to ACB Technology How ACB Systems Compare to Other Systems – Energy Efficiency Figure from: Centre For Building Science News, Lawrence Berkeley Laboratory, “Hydronic Radiant Cooling Systems”, Fall 1994. * Figure does not include additional fan energy associated with developing pressure for active chilled beam operation. Flow Cross Section Ratio 1:550 ¾“ diameter Water Pipe The energy that 1 ft 3 of water removes requires 3,400 ft 3 of air! 18“ x 18“ Air Duct
  10. 10. Section I: Introduction to ACB Technology How ACB Systems Compare to Other Systems – Energy Efficiency <ul><li>Operating cost of the chilled water system can significantly be lower for ACB systems due to the ability to use higher leaving chilled water temperatures </li></ul><ul><ul><li>Improved chiller EER at higher leaving water temperatures </li></ul></ul><ul><ul><li>Allows for downsizing the nominal tonnage of the chiller while maintaining similar output tonnage </li></ul></ul>Chiller Nominal Tonnage LWT Output Tons kWi EER 250 45 257 319.4 9.6 210 55 257 296.2 10.4 190 60 250 276.1 10.8
  11. 11. Section I: Introduction to ACB Technology Common Applications of ACB Technology <ul><li>High sensible cooling load applications </li></ul><ul><ul><li>Heat driven laboratories, offices, etc. </li></ul></ul><ul><li>Sound sensitive applications </li></ul><ul><ul><li>Libraries, hospitals, universities, etc. </li></ul></ul><ul><li>Retrofit applications (CAUTION) </li></ul><ul><ul><li>ACB’s require minimal overhead clearance </li></ul></ul><ul><li>LEED Applications </li></ul><ul><ul><li>Superior energy efficiency, individual temperature control, and innovation </li></ul></ul>
  12. 12. Section I: Introduction to ACB Technology Misapplications of ACB Technology <ul><li>Spaces with high ceilings (above 14’) </li></ul><ul><ul><li>Manufacturing, warehouses, etc. </li></ul></ul><ul><li>Spaces with high latent loads </li></ul><ul><ul><li>Indoor pools, gymnasiums, etc. </li></ul></ul><ul><li>Spaces with uncontrolled humidity </li></ul><ul><ul><li>Atriums, vestibules, hallways, etc. </li></ul></ul><ul><li>Spaces with restrictions on recirculated air </li></ul><ul><ul><li>Class I and Class II hospital areas </li></ul></ul>
  13. 13. Section II: ACB System Design Considerations DOAS/Airside System Design <ul><li>A DOAS is required for the following: </li></ul><ul><ul><li>Dewpoint control to prevent condensation on the ACB’s </li></ul></ul><ul><ul><li>Provide minimum ventilation requirement (ASHRAE Std. 62) </li></ul></ul><ul><ul><li>Must handle 100% of the OA’s latent and sensible load </li></ul></ul><ul><ul><li>Must handle 100% of the zone’s latent load </li></ul></ul><ul><ul><li>Induce sufficient airflow through ACB’s to satisfy zone sensible load </li></ul></ul><ul><ul><li>Positively pressurize building envelope to prevent infiltration </li></ul></ul>
  14. 14. Section II: ACB System Design Considerations DOAS/Airside System Design . <ul><li>There are (2) common DOAS discharge air temperature strategies: </li></ul><ul><li>Low temperature / low dewpoint strategy (type III desiccant) </li></ul><ul><ul><li>Not always recommended due to risk of overcooling the space and/or requiring reheat. Consider in applications high space latent loads. </li></ul></ul><ul><li>“ Neutral air” strategy – thermally neutral but dry air (68-72ºF db / 50-55% RH) </li></ul><ul><ul><li>Maximizes system efficiency, ACB’s handle ≈100% of space sensible load </li></ul></ul><ul><ul><li>Free reheat should be incorporated into DOAS unit (i.e. “alpha plate”, sensible wheels, wrap around heat pipe, hot gas reheat ) </li></ul></ul><ul><ul><li>At summer design conditions, discharge air temperature can be reset colder to satisfy increased loads </li></ul></ul>
  15. 15. Section II: ACB System Design Considerations Chilled Water System Design <ul><li>The ACB’s chilled water supply temperature is dependent on the space’s design dewpoint </li></ul><ul><ul><li>Supply water temperature should be at least 2-3ºF above the space’s design dewpoint to prevent condensation. </li></ul></ul><ul><ul><li>Supply water temperature should be as high as possible to take advantage of increased chiller EER and ability to downsize nominal chiller capacity without reduction in output tonnage. </li></ul></ul><ul><ul><li>Utilizing higher supply water temperatures allows for more available hours for water side economizer. </li></ul></ul><ul><ul><li>ACB chilled water system temperature rise is lower (typically 6-8ºF) compared to traditional hydronic systems (typically 10-12ºF). The system designer should pay close attention to ACB coil water pressure drop to avoid excessive pump head. </li></ul></ul>Chiller Nominal Tonnage LWT Output Tons kWi EER 250 45 257 319.4 9.6 210 55 257 296.2 10.4 190 60 250 276.1 10.8
  16. 16. Section II: ACB System Design Considerations Chilled Water System Design . <ul><li>DEDICATED CHILLER(S) </li></ul><ul><ul><li>Two independent chilled water loops </li></ul></ul><ul><ul><li>Allows higher supply water temperature for ACB chilled water loop </li></ul></ul><ul><ul><li>Increased chiller EER for ACB water loop </li></ul></ul><ul><ul><li>Ability to downsize nominal chiller capacity without reduction in output capacity for ACB water loop </li></ul></ul><ul><ul><li>Higher first cost due to multiple chillers </li></ul></ul>
  17. 17. Section II: ACB System Design Considerations Chilled Water System Design . <ul><li>COMMON CHILLER(S) / MIXING VALVE </li></ul><ul><ul><li>One common chilled water loop </li></ul></ul><ul><ul><li>Mixing valve controlled by sensor installed downstream of the discharge of the secondary pump(s) </li></ul></ul><ul><ul><li>Does not allow for higher supply water temperatures </li></ul></ul><ul><ul><li>Decreased chiller EER </li></ul></ul><ul><ul><li>Cannot downsize nominal chiller capacity </li></ul></ul><ul><ul><li>Should only be considered when ACB chilled water load is significantly less than DOAS load </li></ul></ul>
  18. 18. Section II: ACB System Design Considerations Chilled Water System Design . <ul><li>COMMON CHILLER(S) / HEAT EXCHANGER </li></ul><ul><ul><li>One common chilled water loop </li></ul></ul><ul><ul><li>Modulating control valve controlled by sensor installed in outlet side of the water to water heat exchanger </li></ul></ul><ul><ul><li>Does not allow for higher supply water temperatures </li></ul></ul><ul><ul><li>Decreased chiller EER </li></ul></ul><ul><ul><li>Cannot downsize nominal chiller capacity </li></ul></ul><ul><ul><li>Should only be considered when ACB chilled water load is significantly less than DOAS load; and there is a requirement to isolate primary chilled water loop from the secondary water loop </li></ul></ul>
  19. 19. Section II: ACB System Design Considerations Chilled Water System Design . TRADITIONAL CHILLER(S) / DECOUPLED DOAS <ul><ul><li>DOAS decoupled from chilled water loop </li></ul></ul><ul><ul><li>Allows higher supply water temperature for ACB chilled water loop </li></ul></ul><ul><ul><li>Increased chiller EER for ACB water loop </li></ul></ul><ul><ul><li>Ability to downsize nominal chiller capacity without reduction in output capacity for ACB water loop </li></ul></ul>
  20. 20. Section II: ACB System Design Considerations Chilled Water System Design . <ul><li>GEO CHILLER(S) / DECOUPLED DOAS </li></ul><ul><ul><li>DOAS decoupled from chilled water loop </li></ul></ul><ul><ul><li>Allows higher supply water temperature for ACB chilled water loop </li></ul></ul><ul><ul><li>Increased chiller EER for ACB water loop </li></ul></ul><ul><ul><li>Ability to downsize nominal chiller capacity without reduction in output capacity for ACB water loop </li></ul></ul><ul><ul><li>Can utilize advanced geothermal water to water heat pump technology for exceptional energy efficiency </li></ul></ul><ul><ul><li>Recommended for LEED projects </li></ul></ul>
  21. 21. Section II: ACB System Design Considerations Heating with ACB’s . <ul><li>ACB’s available in 2-pipe in 4-pipe configurations </li></ul><ul><li>Use of ACB’s for heating is dependent on the building envelope </li></ul><ul><ul><li>For internal zone or zones with <300 BTU/ft ACB’s are an excellent option </li></ul></ul><ul><ul><li>For zones between 300-400 BTU/ft, ACB’s can be effective </li></ul></ul><ul><ul><ul><li>Air directed at 75fpm horizontally towards the window </li></ul></ul></ul><ul><ul><li>For zones above 400 BTU/ft, ACB’s are not effective </li></ul></ul><ul><ul><ul><li>Risk of drafts </li></ul></ul></ul><ul><ul><ul><li>Should use finned tube radiation </li></ul></ul></ul><ul><li>For low temperature / low dewpoint primary air systems zone reheat should be incorporated to prevent overcooling the space. </li></ul><ul><ul><li>Typically a reheat coil is installed in the zone’s primary air ductwork </li></ul></ul><ul><ul><li>Alternate option is to utilize a 4-pipe ACB design </li></ul></ul>
  22. 22. Section II: ACB System Design Considerations Controlling ACB Systems . <ul><li>Chilled water flow control </li></ul><ul><ul><li>Each zone’s flow is controlled by a single thermostat and a single control valve </li></ul></ul><ul><ul><li>2-position zone valves (i.e. on/off control) are typically used </li></ul></ul><ul><ul><li>Manual isolation valves should be installed </li></ul></ul>Zone Controls Zone Manifold
  23. 23. Section II: ACB System Design Considerations Controlling ACB Systems <ul><li>Primary air flow control can be balanced with the following: </li></ul><ul><ul><li>Manual balancing damper (i.e. iris type) are used on constant primary airflow systems </li></ul></ul><ul><ul><li>VAV boxes are used on variable primary airflow systems </li></ul></ul><ul><ul><ul><li>Should be considered in zones with highly variable latent loads. </li></ul></ul></ul><ul><ul><ul><li>Demand control ventilation can also be integrated into a VAV control strategy </li></ul></ul></ul><ul><ul><ul><li>Occupancy sensors can be integrated into a VAV control strategy. When zone is unoccupied, VAV box closes. </li></ul></ul></ul>
  24. 24. Section II: ACB System Design Considerations Condensation Prevention <ul><li>Dewpoint control should be primary consideration in the condensation prevention control strategy </li></ul><ul><li>Additional control strategies include: </li></ul><ul><ul><li>The DOAS system should be cycled during unoccupied mode to maintain setback temperature and dewpoint set points. In addition, a “dry out” cycle should be implemented after long periods of unoccupied mode operation (i.e. weekends) </li></ul></ul><ul><ul><li>Dewpoint sensors can be used to detect then disable the ACB system when a condition where condensation could occur is present. Alternately, moisture sensors on water piping can be used. </li></ul></ul><ul><ul><li>Window switches can be used to disable the ACB system when a window is opened and ambient conditions will result in condensation </li></ul></ul>
  25. 25. Section II: Summary Benefits of ACB Technology <ul><li>Energy conservation </li></ul><ul><ul><li>40-70% less primary air, compared to all air systems </li></ul></ul><ul><ul><li>75-100% of the space sensible cooling delivered by water </li></ul></ul><ul><ul><li>Significant reduction in fan energy </li></ul></ul><ul><ul><li>Increased EER of chiller </li></ul></ul><ul><li>Reduced space consumption </li></ul><ul><ul><li>Smaller overall mechanical footprint, reduced duct work size </li></ul></ul><ul><ul><li>Increase of space ceiling height </li></ul></ul><ul><li>Reduced maintenance costs </li></ul><ul><ul><li>No moving parts </li></ul></ul><ul><ul><li>No filters at the beam required, beams vacuumed every 5-10 years </li></ul></ul><ul><li>Increased comfort levels </li></ul><ul><ul><li>Excellent air distribution, </li></ul></ul><ul><ul><li>Secondary air temperature close to room temp. </li></ul></ul><ul><ul><li>Lowe noise level, beam systems typically operate with around 10 dB(A) less noise than traditional VAV systems </li></ul></ul>
  26. 26. Section III: References Dadanco Frequently Asked Questions . Retrieved from: http://www.activechilledbeam.com/chilled_beam_questions.asp Darren Alexander and Mike O’Rourke. Design Considerations for Active Chilled Beams (ASHRAE Journal, 2008, September). Geoffrey P. McMahon. Chilled Beams: The Science of Lab Cooling . Retrieved from: http://www.aeieng.com/downloads/articles/ES%20Jan%20%2009%20Chilled%20Beams.pdf Maija Virta, David Butler, Jonas Graslund, Jaap Hogeling, Erik Lund Kristiansen, Mika Reinikainen, and Gunnar Svensson. REHVA – Chilled Beam Application Guidebook (Federation of European Heating and Air-Conditioning Associations, 2004). Peter Rumsey and John Weale. Chilled Beams in Labs: Eliminating Reheating & Saving Energy on a Budget (ASHRAE Journal, 2007, September) Trox Chilled Beam Design Guide . Retrieved from: http://www.trox.us/usa/service/download_center/structure/technical_documents/air_water_systems/usa_products/leaflets/Chilled_Beam_Design_Guide.pdf
  27. 27. Section III: Summary THANK YOU Questions? Primary Contact Matt Green, Sales Engineer Office: 630-693-0926 Cell: 630-730-4917 Fax: 630-693-0931 [email_address] Secondary Contact Jordan Stiebel, Inside Sales Engineer Office: 630-693-5876 Fax: 630-693-0931 [email_address] www.thermosystemsinc.com

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