central chiller plants - appa · central chiller plants presenter: john vucci ... 6,400 ton...
TRANSCRIPT
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Central Chiller Plants
Presenter: John Vucci
Associate Director HVAC Systems
University of Maryland
College Park, Maryland
Institute for Facilities Management
Dallas, Texas
February 3, 2014
Course 319
Seminar Course Objectives
Provide an introduction to the Planning and Design Process when considering the upgrade of Central Plants
Discuss the basics of Central Plant Designs
Review industry guidelines and standards applicable to developing efficient Central Plants
Discuss examples of Central Plant Designs
Planning Decisions
Sustainability in Design
What type of Central Plant is best for the application Single Building
Multiple Facilities connected
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Today’s Concepts of Green and Sustainable Design
Sustainability: Providing for the needs of the present without detracting from the ability to fulfill the needs of the future
Green and sustainable design achieves a balance of high performing buildings over the life of a facility (CHP) by, Minimizing natural resource consumption Minimizing emissions Minimizing solid waste and liquid effluents Minimizing negative impacts on site ecosystems Maximizes quality of indoor environment
Information from ASHRAE Green Guide: the design and construction and operation of sustainable buildings – 2nd edition 2006
Today’s Concepts of Green and Sustainable Design
Implementing Green/Sustainable design may raise the first cost of the purchase
G/S designs evaluate and contribute to LCC through energy efficiency and operational flexibility rather than simple focus on first cost
Design Considerations
The Architects Team
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Design
Peak design vs. Diversified or part load operation Constant Primary/Variable Secondary Primary Variable Flow Constant Flow Hybrid Designs (using different technologies)
Demand Management of energy Consumption Metering & Controls Integration Ancillary Systems (water Treatment, Refrigeration MER
Ventilation)
Useful Guides and References
ASHRAE Guideline 22: Instrumentation for monitoring Central Chilled Water Plant Efficiency
ASHRAE Standard 15 - 2007: Safety Standard for Refrigeration Systems
ASHRAE Handbook 2008: Chapter 2 Decentralized Cooling and Heating
ASHRAE Handbook 2008: Chapter 3 Central Cooling and Heating Plants
ASHRAE Handbook 2008: Chapter 11 District Heating and Cooling
Future Standard: ASHRAE SPC – 184 MOT Field Testing Package Chillers
ASHRAE / ARI
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Temperature, Flow and BTUH Metering
GPC-22 & SPC-184
Ultrasonic Flow Measurement
3 wire platinum RTD
Basic DesignChiller design is constant flow variable temperature
CHW pumping is constant flowCW pumping is constant flow
CW temperature is controlled by some means (VFD shown)
Basic Design Typically these systems were designed in the past with three-way control
valves across the distribution load. Newer single designs can utilize variable CHW flow with two – way modulating valve control changing the
original design concept to variable flow constant temperature.
Oversized chiller with installed plate & frame heat exchanger connected to another building utilizes variable 2-way control valve. Original 3-way control valve provides plant minimum flow requirements.
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Primary-Secondary Design
Primary Variable Flow
6,400 Ton Variable flow chiller plant serving 21 buildings consists of 2-1,900 Tr chillers & 1-2,600 Tr chiller
2,600 TR electric chiller
1,900 Tr Steam driven chiller
1,900 Tr Steam driven chiller
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Chiller Plant Refrigerant Containment, Ventilation and Safety
Spring loaded relief valves
High efficiency purges
Venting emergency relief piping to atmosphere
Emergency ventilation capability where CFM = 100 x G0.5 (where G is the mass of the largest refrigerant system)
When occupied; General ventilation @ 0.5 cfm/SF and volume not to exceed a MER temperature rise of 18oF
Chiller Plant Refrigerant Containment, Ventilation and Safety
Refrigerant Transfer Equipment for total removal of refrigerant from chiller. Where multiple chillers in a Central Plant are present the storage vessel is sized to hold the largest charge.
Planning for Maintenance
Service access for repairs, equipment access need to be considered
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Planning for MaintenanceCleaning condenser tubes can be one of the most cost effective measures of a maintenance program. Clean condenser heat transfer is critical to the efficient operation of a chiller.
Discussions with manufacturers identify for every 1 oF increase in condenser water temperature compressor energy consumption increases by 2%.
Local Condenser gantry rig for head removal. Ideas for plant consideration is not normally presented by the design team
Technician using tube cleaning for annual cleaning of condenser tubes
Planning for Expansion
Original 2,000 Tr TES Plant
New 2007 2,000 Tr Addition
Additional Space allowed for 1,600 Tr addition
Following the construction of a new Biosciences building (1,400 Tons Peak) a 2,000 Ton chiller addition was constructed to expand an existing 2,000 Ton –
8,900 Tr/Hr TES ICE Plant. Shell construction occurred parallel to the new facility during summer 2007 the chiller equipment was installed and commissioned for readiness. The original Plant decouples the ethylene glycol Primary from water
secondary. The 2,000 TR Plant addition now base loads the summer daily diversified peak of 1,800 tons of capacity, with the TES ICE storage used for Univ.
Demand Response Program.
Components of the Plant designed with sustainability,Chiller: .62 Kw/Tr @ Design 2,000 tons with VFD operation was factory
performance tested @ 9% (180 Tr) at .36 Kw/TrCooling Tower: Uses 2 VFD’s for each fan set to supply 65 oF CWS
CHW Variable 125 HP Pumps: Use VFD to pump CHW from design 4,000 GPM to minimum flow (2,000 GPM) as needed.
4,160 VAC Variable Speed Drive
2,000 Ton R-134a Centrifugal Chiller
Condenser Water Treatment
ASHRAE 15 Refr. Exhaust & Refr. Specific Monitor
Primary Variable
Flow VFD