stephen hart
DESCRIPTION
Frese Grundfos Sytem Design for Energy Efficient PumpingTRANSCRIPT
Variable Flow Systems
System Design For Energy Efficient Pumping
Stephen Hart Managing Director, Frese Limited
Presentation Outline
Introduction
• Energy & Comfort compromise
• Seasonal loads• Constant v
Variable Flow• VSP• Two port
valve• Balancing
Problem
• Fluctuating pressure losses in pipework
• Pressure control• Start Point• End Point• Mid Point
Solution
• Current CIBSE• Pump• Flow• Temperature• Pressure
• OPTIMA PICV Solution• At coil• Remote
Sensor• Sensor
Polling
Power savings
• Schemes• Constant
speed• DPCV
solution• PICV
solution• Power
calculations• Life Cycle
Graph
The Energy & Comfort Compromise
Maintain a comfortable indoor environment• Full load heating on demand• Full load cooling on demand•Effective ventilation• Silent system operation
Reduce system power absorption• Slow motors at low loads•Maximise ΔT at all loads•Prevent overflows at all times•Minimise system resistance
Variable Flow System(Start Point Control)
Variable speed pump and two port temperature control valves VSP (Constant Pressure)
∆p
25 100
Hset
Variable systemcharacteristics
Pump curvemaximum speed
H[%]
Q [%]P1[%]
Q [%]
Variable Flow System(End Point Control)
Variable speed pump and two port temperature control valves VSP (Constant Pressure)
∆p
Hset
100
Hmax
Variable systemcharacteristics
Pump curvemaximum speed
H[%]
Q [%]P1[%]
Q [%]
25
At Full Load
Unstable Temperature Control
Distance
Pres
sure
∆p
∆p
Underflow
Underflow
Overflow
Overflow
At Part Load
Differential Pressure ControlDPCV Across a Branch
As a rule of thumb, limit DPCV setting to 1.5 times the design ΔP of the index on each branch to secure authority at part load
Source: TA
Differential Pressure ControlDPCV Across a Modulating Valve
Perfect solution ensures authority of 1 on modulating valve but is expensive and adds to pump resistance
Source: TA
Variable Flow SystemPressure Independent Control Valve
∆p
One valve replaces:•Two port modulating valve•Automatic balancing valve•Differential pressure control valve
Frese OPTIMA PICV
Maintain minimum required ΔP for PICV and coil at design
Benefits - Design
• Less time to define the necessary equipment for a hydraulic balanced system (only flow data is required)
• No need to calculate valve authority
• Flexibility if the system is modified after the initial installation
Benefits - Installation
• No further regulating valves required in the distribution pipework when PICV is installed at terminals.
• Total number of valves minimized due to the 3-in-1 design
• Minimized commissioning time due to automatic balancing of the system
• No minimum straight pipe lengths required before or after the valve.
Benefits - Operation
• High comfort for the end-users due to high precision temperature control
• Longer life due to less movements of the actuator
• Less energy consumption due to faster response and increased system stability
20
TPE
80-2
50/2
PICV Large SystemEnd Point Control
If either A or B do not have the required ΔP then the pump controller will speed up the pump.
A
B
AB
21Running hours: 6.840 hours/year
Calculating Pump Energy Consumption
Hours4000 60002000
Flow
%
0
100
75
50
25
Load profileCalculation profile
8760 hours/year
8000
Constant SpeedDPCV
2612544261253238
50357515
1006
Pres. kPa
Flow[%]
Hours[%]
4960585067407430
Power W
Total 48815 kWh/year 100%
TP 80-250/2
Mid Point ControlDPCV
1162544144191220
50357515
1006
Pres. kPa
Flow[%]
Hours[%]
1730267043607030
Power W
Total 24278 kWh/year 50%
TPE 80-250/2
Start Point ControlDPCV
2202544220220220
50357515
1006
Pres. kPa
Flow[%]
Hours[%]
4040480058007030
Power W
Total 41605 kWh/year 85%
TPE 80-250/2
End Point ControlPICV
43254466
102154
50357515
1006
Pres. kPa
Flow[%]
Hours[%]
554123025504890
Power W
Total 11827 kWh/year 24%
TPE 80-250/2