Central Chiller Plants

Central Chiller Plants Institute for Facilities Management New Orleans, LA January 18,2016 Course 319 Presenter: John Vucci Associate Director HVAC Systems University of Maryland College Park, Maryland 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 1

Operation Plant flexibility Operations maintenance 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 2 nd 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 2

Design Considerations The Architects Team 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 3

ASHRAE / ARI Temperature, Flow and BTUH Metering GPC-22 & SPC-184 3 wire platinum RTD Ultrasonic Flow Measurement Basic Design Chiller design is constant flow variable temperature CHW pumping is constant flow CW pumping is constant flow CW temperature is controlled by some means (VFD shown) 4

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. Primary-Secondary Design Primary Variable Flow 5

1,900 Tr Steam driven chiller 1,900 Tr Steam driven chiller 2,600 TR electric chiller 6,400 Ton Variable flow chiller plant serving 21 buildings consists of 2-1,900 Tr chillers & 1-2,600 Tr chiller Thermal Energy Storage - ICE 6

Hydronic Decoupler or Crossover 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 G 0.5 (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 18 o F 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. 7

Planning for Maintenance Service access for repairs, equipment access need to be considered Planning for Maintenance Cleaning 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 o F increase in condenser water temperature compressor energy consumption increases by 2%. Technician using tube cleaning for annual cleaning of condenser tubes Local Condenser gantry rig for head removal. Ideas for plant consideration is not normally presented by the design team Planning for Expansion 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. Original 2,000 Tr TES Plant New 2007 2,000 Tr Addition Additional Space allowed for 1,600 Tr addition 8

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/Tr Cooling Tower: Uses 2 VFD s for each fan set to supply 65 o F CWS CHW Variable 125 HP Pumps: Use VFD to pump CHW from design 4,000 GPM to minimum flow (2,000 GPM) as needed. Primary Variable Flow VFD ASHRAE 15 Refr. Exhaust & Refr. Specific Monitor 4,160 VAC Variable Speed Drive Condenser Water Treatment 2,000 Ton R-134a Centrifugal Chiller KW/Ton, EER & COP (Coefficient of Performance) KW/Ton is the Energy Input in KW to produce 1-Ton of Chilled Water COP is the Coefficient of Performance EER is the Energy Efficiency Ratio Each is a ratio of Energy In to generate the Energy Out Useful Formulas KW/Ton = 12/ EER KW/Ton = 12 / (COP x 3.412) COP = 12 / (KW/Ton) / 3.412 COP = EER / 3.412 EER = 12 / KW/Ton EER = COP x 3.414 1KW/Ton = 3.5COP 1KW/Ton = 12 EER 9

Plant KW/Ton What plants are the most efficient? Lower is better! Can you guess which Plant is Best? B425 Prince Frederick Hall B224 Wing 2 Computer B416 SCUB 5 B046 Marie Mount SCUB B224 Wing 4 Computer 2.5 2 1.5 1 0.5 0 2015 KW/Ton 10

What plants are the most efficient? B425 Prince Frederick Hall B224 Wing 2 Computer B416 SCUB 5 B046 Marie Mount SCUB B224 Wing 4 Computer 2015 KW/Ton 2.5 2 1.5 1 0.5 0 B425 Prince B224 Wing 2 B416 SCUB 5 B046 Marie B224 Wing 4 Frederick Hall Computer Mount SCUB Computer SCUB Space Science Space Science SCUB SCUB Plant COP What plants have the best COP? B224 Wing 4 Computer B046 Marie Mount SCUB B416 SCUB 5 B224 Wing 2 Computer 425 Prince Frederick Hall SCUB 5.84 B224 Wing 4 Computer Spaces Sciences 3.98 B046 Marie Mount COP COP 3.74 2.33 B416 SCUB 5 B224 Wing 2 Computer Spaces Sciences 1.58 B425 Prince Frederick Hall SCUB Plant EER B224 Wing 4 Computer B046 Marie Mount SCUB B416 SCUB 5 B224 Wing 2 Computer 425 Prince Frederick Hall SCUB 5.23612 7.72162 EER 12.39436 13.18972 19.35376 B425 PRINCE B224 WING 2 B416 SCUB 5 B046 MARIE B224 WING 4 FREDERICK COMPUTER MOUNT COP COMPUTER HALL SCUB SPACES SPACES SCIENCES SCIENCES 11

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Closing Questions 13