Transcript EnergyPlus Training Part 1

Lecture 22: Primary System
Loops in EnergyPlus
Material prepared by GARD Analytics, Inc. and University of Illinois
at Urbana-Champaign under contract to the National Renewable Energy
Laboratory. All material Copyright 2002-2003 U.S.D.O.E. - All rights reserved
Purpose of this Lecture
Gain an understanding of:


Water (fluid) side loop structures in
EnergyPlus
How to control fluid flow rates using the
EnergyPlus pump strategies
2
Defining Loops
Loops define the movement of mass
and energy within an HVAC system

Plant loop

Condenser loop

Heat recovery loop
Systems defined by the order of
branches/components on the HVAC loop
3
Defining Loops (cont’d)
Main loops divided into “sub-loops” or
“semi-loops” for organizational clarity &
simulation logistics
Sub-loops are matched pairs that
consist of half of the main loop.
For example, plant and condenser loops
are broken into supply and demand
sides.
4
Demand- & Supply-Side
Sub-Loops
Plant demand-side sub-loop contains
equipment that creates a load on the
plant.
Plant supply-side sub-loop contains
equipment that meets these loads.
Each supply-side sub-loop must be
connected to a demand-side loop.
5
Demand- & Supply-Side Loops
(cont’d)
Heating Coil
HW Pump Outlet Node
±
Heating Coil
Inlet Node
HW Demand
Outlet Node
Exit Pipe
Heating Coil
Inlet Pipe
Outlet Node
HW Demand Inlet Node
HW Pump
HW Supply inlet Node
Boiler Inlet Node
Boiler
HW Supply Outlet Node
Boiler Outlet Node
HW Supply Outlet Pipe
Demand-Side Loop
Supply-Side Loop
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Branches for Water-Side
Loops
Maximum Branch Flow Rate (Ignored)
Comp1 Type
Comp1 Name
Comp1 Inlet Node Name
Comp1 Outlet Node Name
Comp1 Branch Control Type
7
Branches for Water-Side
Loops - Example
BRANCH,
Heating Supply Inlet Branch,
!- Branch Name
,
!- Maximum Branch Flow Rate {m3/s}
PUMP:VARIABLE SPEED,
!- Comp1 Type
HW Circ Pump,
!- Comp1 Name
HW Supply Inlet Node,
!- Comp1 Inlet Node Name
HW Pump Outlet Node,
!- Comp1 Outlet Node Name
ACTIVE;
!- Comp1 Branch Control Type
8
Layout for Individual HVAC
Supply or Demand Sub-Loops
A
 Elements can be defined in
series, in parallel, or both
with some restrictions
 Branches are defined as
individual legs within the
loop structure
 Segment between point A &
B is defined as a branch, as
is the section between
points E and F
1 to m
Components
B
n Splitter
C1
Cn
...
1 to i
Components
D1
1 to j
Components
Dn
n Mixer
E
1 to k
Components
F
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Layout for Individual HVAC
Supply or Demand Sub-Loops
A
 The first supply side
component between A & B
must be the loop pump,
which controls the loop flow.
 There may be multiple
branches between the
splitter and mixer (between
points C1 & D1 to Cn & Dn).
 Each sub-loop may only
have one splitter and one
mixer.
1 to m
Components
B
n Splitter
C1
Cn
...
1 to i
Components
D1
1 to j
Components
Dn
n Mixer
E
1 to k
Components
F
10
Layout for Individual HVAC
Supply or Demand Sub-Loops
A
 Equipment may be in
parallel between the mixer
and splitter,
 Within any branch, there
can only be elements in
series.
 Sub-loops do not require a
splitter or mixer, if all
equipment on the sub-loop
is in series—a single branch
defines the entire sub-loop.
1 to m
Components
B
n Splitter
C1
Cn
...
1 to i
Components
D1
1 to j
Components
Dn
n Mixer
E
1 to k
Components
F
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Pumping Rules
Supply-Side Sub-Loop
 Pumps must be on the
supply side
From DemandSide Sub-Loop
 Pumps can operate as
constant or variable flow
 Pumps can run
continuously or
intermittently
Loop Pump
Splitter
Components
To DemandSide Sub-Loop
Mixer
12
Pumping Rules (cont’d)
 Single boiler/chiller with NO bypass,
PUMP:CONSTANT SPEED


Boiler/chiller should be constant flow
Pump should be intermittent
 Single boiler/chiller with NO bypass,
PUMP:VARIABLE SPEED

Boiler/chiller should be variable flow, regardless of
whether pump is intermittent or continuous (runs at
the minimum if demand is less than minimum, this
includes zero.)
13
Pumping Rules (cont’d)
Single boiler/chiller with bypass,
PUMP:CONSTANT SPEED

Boiler/chiller can be constant or variable
flow

Pump may be intermittent or continuous as
long as the bypass can handle the entire
pump volume when the boiler is not
operating
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Pumping Rules (cont’d)
 Multiple branches add more complexity, but it
is nothing more than continuity.
 If the pump is putting out flow then it has to
have a branch to flow down whether it is a
chiller or a bypass.
15
Pumping Rules (cont’d)
 You are always safer adding the bypass for a
simulation. If the active machines require the
flow the bypass will be dry
 Thermodynamically it does not make any
difference if the flow goes through a machine
that is OFF or it flows down the bypass.
 There is no pressure simulation and flow
losses are not accounted for.
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Summary of Loop Limitations
 Each sub-loop allowed one splitter and one
mixer
 One bypass on each sub-loop optional
 No other components may be in series with a
bypass
 Equipment may be in parallel only between
the splitter and mixer
 Equipment may be in series in each branch
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3-Zone VAV System
We are going to look at this system input Loop by Loop
Outside Air
Plant Supply Side
Cooling Loop
Supply Fan
CW Pump
Bypass
CC Plant Demand Side
Cooling Loop
Mixed Outside
Air Box
Bypass
Chiller
Relief Air
East
North
Zone
VAV Box: ReHeat
Return Hot
VAV Box: ReHeat
Cond . Demand
Side Loop
Boiler
Cond . Pump
HW Pump
Zone
Water Mixer
Return Air Mixer
Hot Water
Splitter
VAV Box: ReHeat
Zone Air Splitter
Zone
Plant Demand Side
Heating Loop
Resistive
Condenser
Bypass
Condenser
Bypass
Plant Supply Side
Heating Loop
Bypass
Cooling
Tower
Cond . Supply Side Loop
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Cooling Coil & Chilled Water
Demand Side
Outside Air
Plant Supply Side
Cooling Loop
Supply Fan
CW Pump
CC Plant Demand Side
Cooling Loop
Bypass
Mixed Outside
Air Box
Bypass
Chiller
Relief Air
Boiler
Cond . Pump
Zone
VAV Box: ReHeat
Return Hot
VAV Box: ReHeat
North
Cond . Demand
Side Loop
HW Pump
Water Mixer
Return Air Mixer
Splitter
East
Zone
Hot Water
VAV Box: ReHeat
Zone Air Splitter
Zone
Plant Demand Side
Heating Loop
Resistive
Condenser
Bypass
Condenser
Bypass
Plant Supply Side
Heating Loop
Bypass
Cooling
Tower
Cond . Supply Side Loop
19
Cooling Coil & Chilled Water
Demand Side
CC
Cooling Coil
Chilled Water Demand -Side Outlet Node
Bypass
Chilled Water Demand -Side Inlet Note
Objects required:

BRANCH LIST

CONNECTOR LIST

SPLITTER

MIXER

BRANCH, VAV Sys 1 ChW-Branch
 COIL:Water:DetailedFlatCooling, VAV SYS 1 Cooling Coil
20
Cooling Coil & Chilled Water
Demand Side (cont’d)
CC
Cooling Coil
Chilled Water Demand -Side Outlet Node
Bypass
Chilled Water Demand -Side Inlet Note
Objects required (cont’d):

BRANCH, Chilled Water Loop 1 CHW Inlet Branch
 PIPE

BRANCH, Chilled Water Loop 1 CHW Outlet Branch
 PIPE

BRANCH, Chilled Water Loop 1 CHW Bypass Branch
 PIPE
21
Hot Water Demand Side
Outside Air
Plant Supply Side
Cooling Loop
Supply Fan
CW Pump
CC Plant Demand Side
Cooling Loop
Bypass
Mixed Outside
Air Box
Bypass
Chiller
Relief Air
Cond . Pump
HW Pump
Zone
VAV Box: ReHeat
Return Hot
VAV Box: ReHeat
North
Cond . Demand
Side Loop
Boiler
Zone
Water Mixer
Return Air Mixer
Splitter
East
Hot Water
VAV Box: ReHeat
Zone Air Splitter
Zone
Plant Demand Side
Heating Loop
Resistive
Condenser
Bypass
Condenser
Bypass
Plant Supply Side
Heating Loop
Bypass
Cooling
Tower
Cond . Supply Side Loop
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Hot Water Coils & Demand
Side


 COIL:Water:SimpleHeating(3)

BRANCH, HW Outlet Branch
HW Splitter

VAV Box:
Reheat
VAV Box:
Reheat
BRANCH, HW Inlet Branch

BRANCH, HW Bypass Branch
VAV Box:
Reheat
Bypass
 PIPE
Return HW Mixer
 PIPE

Zone Air Splitter

BRANCH LIST
CONNECTOR LIST
SPLITTER
MIXER
BRANCH,Zone X Reheat
Branch (3)
Plant Demand Side

Heating Loop
Objects required:
 PIPE
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Hot Water Loop Supply Side
Outside Air
Plant Supply Side
Cooling Loop
Supply Fan
CW Pump
CC Plant Demand Side
Cooling Loop
Bypass
Mixed Outside
Air Box
Bypass
Chiller
Relief Air
VAV Box: ReHeat
North
Cond . Demand
Side Loop
Boiler
Cond . Pump
HW Pump
Return Hot
Water Mixer
Return Air Mixer
East
Zone
Heating Loop
Hot Water
Splitter
VAV Box: ReHeat
Zone Air Splitter
Zone
Plant Demand Side
Resistive
Condenser
Bypass
Condenser
Bypass
Plant Supply Side
Heating Loop
Bypass
Cooling
Tower
Zone
VAV Box: ReHeat
Cond . Supply Side Loop
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Hot
Water
Loop
Supply
Side
Hot Water Loop Supply Side





PLANT LOOP
BRANCH LIST
CONNECTOR LIST
SPLITTER
MIXER
BRANCH, Supply Inlet Branch
 PUMP:VARIABLE SPEED
HW Supply
Outlet Node
Boiler
Outlet Node
Bypass

Plant Demand Side
Heating Loop
Objects required:
Boiler
Boiler
Inlet Node
HW Supply
Inlet Node
HW Pump
HW Pump
Outlet Node
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Hot Water Loop Supply Side
(cont’d)
BRANCH, Boiler Branch
 BOILER:SIMPLE

BRANCH, Supply Bypass Branch
 PIPE

BRANCH, Supply Outlet Branch
HW Supply
Outlet Node
Boiler
Boiler
Inlet Node
HW Supply
Inlet Node
 PIPE

Boiler
Outlet Node
Bypass

Plant Demand Side
Heating Loop
Objects required:
PLANT OPERATION SCHEME
HW Pump
HW Pump
Outlet Node
 HEATING LOAD RANGE BASED OPERATION
 HEATING LOAD RANGE EQUIPMENT LIST
26
Chilled Water Supply Side
Outside Air
Plant Supply Side
Cooling Loop
Supply Fan
CW Pump
CC Plant Demand Side
Cooling Loop
Bypass
Mixed Outside
Air Box
Bypass
Chiller
Relief Air
VAV Box: ReHeat
North
Cond . Demand
Side Loop
Boiler
Cond . Pump
HW Pump
Return Hot
Water Mixer
Return Air Mixer
East
Zone
Plant Demand Side
Hot Water
Splitter
VAV Box: ReHeat
Zone Air Splitter
Zone
Heating Loop
Resistive
Condenser
Bypass
Condenser
Bypass
Plant Supply Side
Heating Loop
Bypass
Cooling
Tower
Zone
VAV Box: ReHeat
Cond . Supply Side Loop
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Chilled Water Supply Side
Plant Supply Side
Cooling Loop
CW Pump
Bypass
Plant Demand Side
Cooling Loop
Chiller
Objects required:





PLANT LOOP, Chiller Plant Chilled Water Loop
BRANCH LIST
CONNECTOR LIST
SPLITTER
MIXER
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Chilled Water Supply Side
(cont’d)
Plant Supply Side
Cooling Loop
CW Pump
Bypass
Plant Demand Side
Cooling Loop
Chiller
Objects required (cont’d):

BRANCH, Chiller Plant Cooling Supply Inlet Branch
 PUMP:VARIABLE SPEED

BRANCH, Chiller Plant Chiller Branch
 CHILLER:Electric

BRANCH, Chiller Plant Cooling Supply Bypass Branch
 PIPE
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Chilled Water Supply Side
(cont’d)
Plant Supply Side
Cooling Loop
CW Pump
Bypass
Plant Demand Side
Cooling Loop
Chiller
Objects required (cont’d):

BRANCH, Chiller Plant Cooling Supply Outlet Branch
 PIPE

PLANT OPERATION SCHEMES
 COOLING LOAD RANGE BASED OPERATION
 COOLING LOAD RANGE EQUIPMENT LIST
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Condenser Loop Demand Side
Outside Air
Plant Supply Side
Cooling Loop
Supply Fan
CW Pump
CC Plant Demand Side
Cooling Loop
Bypass
Mixed Outside
Air Box
Bypass
Chiller
Relief Air
Cond . Pump
HW Pump
VAV Box: ReHeat
North
Cond . Demand
Side Loop
Boiler
Zone
Return Hot
Water Mixer
Return Air Mixer
East
Plant Demand Side
Hot Water
Splitter
VAV Box: ReHeat
Zone Air Splitter
Zone
Heating Loop
Resistive
Condenser
Bypass
Condenser
Bypass
Plant Supply Side
Heating Loop
Bypass
Cooling
Tower
Zone
VAV Box: ReHeat
Cond . Supply Side Loop
31
Condenser Loop Demand Side
Objects required:





BRANCH LIST
CONNECTOR LIST
SPLITTER
MIXER
BRANCH, Condenser Demand Inlet Branch
 PIPE

BRANCH, Chiller Condenser Branch
Plant Supply Side
Cooling Loop
Chiller
Condenser
Bypass
 CHILLER:Electric

BRANCH, Cond. Demand Bypass Branch
 PIPE

BRANCH, Cond. Demand Outlet Branch
 PIPE
Condenser Supply
Side Loop
32
Condenser Supply Side
Outside Air
Plant Supply Side
Cooling Loop
Supply Fan
CW Pump
CC Plant Demand Side
Cooling Loop
Bypass
Mixed Outside
Air Box
Bypass
Chiller
Relief Air
Cond . Pump
HW Pump
VAV Box: ReHeat
North
Cond . Demand
Side Loop
Boiler
Zone
Return Hot
Water Mixer
Return Air Mixer
East
Heating Loop
Hot Water
Splitter
VAV Box: ReHeat
Zone Air Splitter
Zone
Plant Demand Side
Resistive
Condenser
Bypass
Condenser
Bypass
Plant Supply Side
Heating Loop
Bypass
Cooling
Tower
Zone
VAV Box: ReHeat
Cond . Supply Side Loop
33
Condenser
Supply
Side
Condenser Loop Supply Side
Objects required:






CONDENSER LOOP
BRANCH LIST
CONNECTOR LIST
SPLITTER
MIXER
BRANCH, Supply Inlet Branch
Condenser Demand
Side Loop
Condenser
Pump
Condenser
Bypass
 PIPE

BRANCH, Condenser Branch
 COOLING TOWER:Single Speed
Cooling
Tower
34
Condenser
Loop
Supply
Side
Condenser
Supply
Side
(cont’d)
Objects required (cont’d):

BRANCH, Cond. Supply Bypass Branch
 PIPE

BRANCH, Supply Output Branch
 PIPE

Condenser Demand
Side Loop
CONDENSER OPERATION SCHEMES
Condenser
Pump
Condenser
Bypass
 COOLING LOAD RANGE BASED
OPERATION
 LOAD RANGE EQUIPMENT LIST
Cooling
Tower
35
Summary
 Loops are backbone of HVAC simulation
 all equipment attached to air or fluid loops
 Loop structure permits assembly of any
system through input—not hardwired
 Primary system may consist of four different
loops: plant supply and demand, condenser
supply and demand
 Pumps regulate flow while attempting to
meet requests on both sides of each loop pair
 Individual loops may have components in
series and parallel with some limitations
36