Lecture Objectives Finish with thermal storage systems Plumbing
Lecture Objectives: • Finish with thermal storage systems • Plumbing • Hydronic distribution systems – Chiller/Boiler – Storage – Building
Installation of Thermal Storage System Upstream • Increases chiller efficiency • Increases chiller capacity • Overall system efficiency ? ? ? • Decreases storage capacity • Simplifies system layout • …. . Downstream • Decreases chiller efficiency • Decreases chiller capacity Overall 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_Design. Guidelines_Cool. Tools. Chilled. Water. pdf
Hydronic systems for district cooling/heating and buildings Constant-Flow System, Single Chiller, Single Coil Mixing valve that control by-pass flow Major pumping force is the chiller pump Constant-Flow System, Single Chiller, Multiple Coils
Control of coil temperature Mixing valve that control the flow through the coil Flow Variation as a Function of Valve Position Same pressure drop like a cooling coil Major pumping force is the chiller pump
Multiple chiller (or boilers) Parallel Serial
Primary-Loop Only Variable Speed 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 Arrangements Dedicate 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 Radiators Baseboard heaters Fan coil systems
Hydronic Terms • Head loss • Open-loop vs. closed loop
Head Loss
Fittings
Pumps • Raise pressure and produce flow • Main type • Centrifugal Example of Turbine pump Inline Base mounted
Pump curves • NPSHR = Net Positive Suction Head Required
Changing Pump Speed
Curve for Multiple Pumps
Net Positive Suction Head (cavitation)
- Slides: 24