Lecture Objectives Plumbing Hydronic distribution systems ChillerBoiler Storage
Lecture Objectives: • Plumbing • Hydronic distribution systems – Chiller/Boiler – Storage – Building • Pumps Reading assignment: Chilled Water Plant Design Guide (Section 4) http: //energydesignresources. com/media/2305/EDR_Design. Guidelines_Cool. Tools. Chilled. Water. pdf
Primary/Secondary and Tertiary Pumping (schematics A&B below)
Coil Pumping Strategies Variable speed pumps vs. Single pas Valve vs. Mixing valves vs. Diverting Valves
Impact of Piping Coil How will this affect needed CHW flow? What about the chiller performance?
Plumbing Arrangement in Building’s Hydronic Systems Radiators Baseboard heaters Fan coil systems
What is the difference between these two configuration?
Hydronic Terms • Head loss • Open-loop vs. closed loop • Open System h Pump • Closed System Chiller Pump Cooling coil in AHU
Is this open or closed system ? Cooling towers
Relationship between velocity in a pipe and pressure drop Δp ~ v 2 Δp = Constant × v 2 Required power (P) for the pump P = V × Δp Δp [Pa or ft water] smaller pipe larger pipe P –power [W], V –volume flow rate [m 3/s], Δp – pressure drop [Pa] v – velocity [m/s] Δp ~ v 2 (Δp ~ V 2 – when same pipe is used) P ~ V × V 2 – when same pipe is used P ~ V 3 P 2/P 1 = (V 2/V 1)3 For the same pipe When different pipe is used for the same flow rate: For the same flow rate V Reduction of D: D 1 A 1 V 1 P 1 D 2= D 1/2 A 2=1/22 A 1 V 2=22 V 1 P 2/P 1 = (D 1/D 2)4 - for the same flow rate or 50% smaller diameter of the pipe v [m/s or fpm] for the same flow rate wee have: 4 times larger velocity 16 times larger pressure drop and 16 times lager power for the pump
Head Loss
Fittings
Pumps • Raise pressure and produce flow • Main type • Centrifugal Example of Turbine pump Inline Reading (textbook) Page 3 -36 - 3 -45 Base mounted
Pump curves • NPSHR = Net Positive Suction Head Required
Changing Pump Speed
Net Positive Suction Head (cavitation)
Curve for Multiple Pumps
System Curves ∆p A+B B A+B A B V A B Parallel V A B Serial
Find a system curve for this plumbing configuration
System balancing AHU 1 AHU 2 HC 1 HC 2 100 ft 10 gpm 2 gpm 10 ft pump BOILER
Valves • Section 5 -14 and 6 -15 in the textbook • Types • Butterfly Valves • Ball Valves • Globe Valves Three way valves
Valve Sizing and Flow Coefficient Cv value: in liter/hour or…. in Pa Control Valve Selection For Hydronic Systems reference: http: //www. google. com/url? sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact =8&ved=0 CCUQFj. AA&url=http%3 A%2 F%2 Fbookstore. ashrae. biz%2 Fjournal%2 Fdo wnload. php%3 Ffile%3 Dhegberg. pdf&ei=Ivcq. U_O 1 KMu. E 2 AWglo. Hg. DA&usg=AFQj. CN FRAMz. Pnbz. Dp. Aluhyk 4 l 8 u_SKKTdw
Control Valve Selection For Hydronic Systems Before DC we tried to do this Valve authority
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