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)