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Lecture Objectives:
• Finish with thermal storage systems
• Plumbing • Hydronic distribution systems
–Chiller/Boiler – Storage – Building
Installation of Thermal Storage System
DownstreamUpstream
• Increases chiller efficiency • Increases chiller capacity • Overall system efficiency ??? • Decreases storage capacity• Simplifies system layout• …..
• Decreases chiller efficiency• Decreases chiller capacityOverall system efficiency ???• Increases storage capacity•……• Does not allow chiller shut down!
Modeling
Write energy and mass balancer equation for each section
Plumbing Arrangement for Chillers
(and Boilers)• Primarily water circulation loop only
• Primarily & Secondary circulation loops
• Primarily & Secondary & Tertiary loops
• ….
Reading assignment:
Chilled Water Plant Design Guide (Section 4)http://energydesignresources.com/media/2305/EDR_DesignGuidelines_CoolToolsChilledWater.pdf
Hydronic systems for district cooling/heating and buildings
Constant-Flow System, Single Chiller, Single Coil Constant-Flow System, Single Chiller, Multiple Coils
Mixing valve that control by-pass flow Major pumping force is the chiller pump
Control of coil temperature Mixing valve that control the flow through the coil Flow Variation as a Function of Valve Position
Major pumping force is the chiller pump
Same pressure drop like a cooling coil
Multiple chiller (or boilers) Parallel Serial
Primary-Loop Only VariableSpeed Flow
Single chiller Multiple chillers
Primary and Secondary Loop Variable Flow Design
Parallel chillers
Serial chillers
Large Plant or Building Distribution Systems
Primary/Secondary Loops with Variable Flow and Distributed Pumping
Primary/Secondary and Tertiary Pumping
Primary Pump ArrangementsDedicate a pump for each chiller
Provide a common header for the pumps
Coil Pumping Strategies
Variable speed pumps vs. Single pas Valve vs. Mixing valves vs. Diverting Valves
Impact of Piping Coil
Plumbing Arrangement in Building’s hydronic systems
Fan coil systems Baseboard heaters
Radiators
Hydronic Terms
• Head loss
• Open-loop vs. closed loop
Head Loss
Fittings
g
Vkh
2
2
Pumps• Raise pressure and produce flow
• Main type• Centrifugal
Inline Base mounted
Example of Turbine pump
Pump curves
• NPSHR = Net Positive Suction Head Required
Changing Pump Speed
Curve for Multiple Pumps
Net Positive Suction Head(cavitation)
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