Transcript EnergyPlus Training Part 1

Lecture 13: HVAC Loops,
Nodes, and Connections
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
Importance of this Lecture to the
Simulation of Buildings
 So far, we have discussed how much heating or
cooling energy is required to maintain a particular
thermal environment inside a building
 Something must meet these heating and cooling
loads in order for the thermal comfort goals to be
metHVAC system
 “System” or secondary system meets thermal loads
of the zones
 Primary system (central plant) produces or converts
energy for use by the secondary system
 Primary and secondary systems are not perfectly
efficient and will impact the energy consumption of a
buildingthus, we need to simulate these as well
2
Purpose of this Lecture
Gain an understanding of:


Structure of an HVAC (primary and
secondary) system
How an HVAC system is described within
EnergyPlus (big picture)
3
Keywords Covered in this Lecture
Branch
Branch List
Connector List
Splitter and Zone Splitter
Mixer and Zone Mixer
Node List
4
HVAC Input Overview
 Hierarchical set of objects






Loops (air, chilled & hot water, condenser)
Supply and demand sides
Topology of sides: branches, splitters, and mixers
Branches: components along a single duct or pipe
Components: specific pieces of equipment
Nodes: store components’ inlet & outlet conditions
5
HVAC Input Overview (cont’d)
Multiple systems or zone components
can serve each zone
EnergyPlus HVAC simulation attempts to
satisfy the conflicting demands of:

Input simplicity & usability

Input flexibility & generality

Simulation robustness
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EnergyPlus HVAC Loop Overview
Loop Types:

Air Loop

Zone Equipment Loop

Plant Loop Supply Side

Plant Loop Demand Side

Condenser Loop Supply Side

Condenser Loop Demand Side
7
Air Loop
Air side of the secondary system
Typically contains equipment such as a
fan, coils, mixing box, etc.
Where the centralized conditioning of
air takes place—before splitting off to
zones, before reheat, before individual
VAV dampers, etc.
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Zone Equipment Loop
Equipment that is more specific to a
particular thermal zone
May include splitters and air distribution
units which split up flow from the air
loop
Can have multiple systems serving
individual zones
9
Zone Equipment Schematic
Zone
Supply Air
Splitter
Return Air
Path
Dual
Duct
Constant
Volume
(CV)
Zone Exhaust Branch (Opt.)
Dual
Duct
VAV
Air
Distribution
Unit
Zone 1
None
Single
Duct CV
Reheat
Select One
Air
Distribution
Unit
Options
Low
Temp
Radiant
Select One
High
Temp
Radiant/
Convective
Local
Convective
Units
Single
Duct
VAV:
Reheat
Diagram from Input Output
Reference p. 208 (not all
equipment types are included)
Select One
Select
One
Low
Temp
Radiant
Panels
Low Temp Rad
Alternatives
High
Temp
Radiators
Radiators
Hi Temp Rad/Conv
Alternatives
Baseboards
Window
AC
Fan Coil
Unit
Heater/
Ventilator
Air-Air
HP
Water-Air
HP &
Ground
Source
HP
Local Conv. Unit Alternatives
10
Plant Demand Side
Water side of coils, radiant systems, etc.
that require conditioned fluid to provide
either heating or cooling to the zone
(the “demand”)
Connects to air loop or zone equipment
loop through individual components
Connects to plant supply side through
direct fluid connection
11
Plant Supply Side
 Supplies hot or cold fluid to meet the
demands of the plant demand side
 Equipment may include pumps, chillers,
boilers, etc.
 Typically controls both flow rate (via pump)
and temperature (loop setpoint)
 Connects directly to plant demand side
 Connected indirectly to condenser demand
side through components
12
Condenser Supply and Demand
Sides
 Analogous to plant supply and demand sides
 Condenser demand receives heat rejection from plant
supply side equipment
 Condenser supply side tries to supply the conditioned
fluid by rejecting heat to external environment
 Condenser supply side may only be connected to
condenser demand side
 Condenser demand side also connected indirectly to
plant supply side through components and may also
be connected to air loop and zone equipment loop
through components
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EnergyPlus HVAC Loop
Interaction
Building Systems Simulation Manager
Zone
Zone
Simulate Building
Conditions
Predictor
Conditions
Systems
Corrector
Plant Loop
Demand
Supply
Air Loop
Main Air Handler
Condenser Loop
Coils,
Baseb.,
etc.
Plant
Equip.
Demand
Supply
Cond.,
Coils,
etc.
Towers,
Wells,
etc.
Zones & Equip.
14
EnergyPlus HVAC Loop Structure
General rules on EnergyPlus loop
structure:




Maximum of one “parallel” section per loop
Maximum of one splitter and one mixer per
loop
Equipment may be arranged in series on
any particular branch
Only one bypass (in a parallel section) per
loop
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Loops, Branches, Components,
and Nodes
Comp
Branches
Components
…
Splitter
Loop
Comp
Comp
Comp
…
…
…
…
Comp
…
Mixer
Comp
…
Nodes
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EnergyPlus Branches
 Definition: a collection of components
connected in series
 Branches are linked together through
connection components (splitters and mixers)
 A loop may consist of a single branch or
multiple branches
 Input keywords:


Branch
Branch List
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Branch
Lists components and nodes associated
with the components on the branch
Only used for air branches
Example:
BRANCH,
Zone 3 Reheat Branch,
0,
COIL:Water:SimpleHeating,
Reheat Coil Zone 3,
Zone 3 Reheat Water In Node,
Zone 3 Reheat Water Out Node,
ACTIVE;
!!!!!!!-
Branch Name
Maximum Branch Flow Rate {m3/s}
Comp1 Type
Comp1 Name
Comp1 Inlet Node Name
Comp1 Outlet Node Name
Comp1 Branch Control Type
Options are: ACTIVE, PASSIVE, and
BYPASS; determines which component
tried to control the flow on the branch
Repeated for each
component on the
branch
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Branch List
Used by loops to determine which
branches are a part of the loop
Example:
BRANCH LIST,
Condenser Demand Side Branches,
Condenser Demand Inlet Branch,
Little Chiller Condenser Branch,
Big Chiller Condenser Branch,
Condenser Demand Bypass Branch,
Condenser Demand Outlet Branch;
!!!!!!-
Branch
Branch
Branch
Branch
Branch
Branch
List
Name
Name
Name
Name
Name
Name
1
2
3
4
5
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Connector List
Used by loops to determine which
connectors (splitters and mixers) are a
part of the loop
Maximum of one each allowed (two
total)
Connector type must be SPLITTER or
MIXER
CONNECTOR LIST,
Condenser Demand Side Connectors,
SPLITTER,
Condenser Demand Splitter,
MIXER,
Condenser Demand Mixer;
!!!!!-
Connector List Name
Type of Connector 1
Name of Connector 1
Type of Connector 2
Name of Connector 2
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Splitter
Used to distribute fluid flow into various
parallel legs in a loop
Single inlet branch
One or more outlet branches (50 max)
SPLITTER,
CW Loop Splitter,
CW Pump Branch,
Little Chiller Branch,
Big Chiller Branch,
Purchased Cooling Branch,
Supply Bypass Branch;
!!!!!!-
SplitterName
Inlet Branch Name
Outlet Branch Name
Outlet Branch Name
Outlet Branch Name
Outlet Branch Name
1
2
3
4
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Zone Splitter
Same as Splitter except used for air
loops
Single inlet branch
One or more outlet branches (50 max)
ZONE SPLITTER,
Zone Supply Air Splitter,
Zone Equipment Inlet Node,
Zone 1 Reheat Air Inlet Node,
Zone 2 Reheat Air Inlet Node,
Zone 3 Reheat Air Inlet Node;
!!!!!-
Splitter Name
Inlet_Node
Outlet Node 1
Outlet Node 2
Outlet Node 3
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Mixer
Used to combine or mix several parallel
branches back together again
Opposite of a Splitter
One outlet, one to 50 inlet branches
MIXER,
Heating
Heating
Heating
Heating
Supply Mixer,
Supply Outlet Branch,
Purchased Hot Water Branch,
Supply Bypass Branch;
!!!!-
MixerName
Outlet Branch Name
Inlet Branch Name 1
Inlet Branch Name 2
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Zone Mixer
Same as Mixer except used for air loops
Single outlet branch
One or more inlet branches (50 max)
ZONE MIXER,
Zone Return Air Mixer,
Return Air Mixer Outlet,
Zone 1 Outlet Node,
Zone 2 Outlet Node,
Zone 3 Outlet Node;
!!!!!-
Mixer Name
Outlet Node
Inlet Node 1
Inlet Node 2
Inlet Node 3
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EnergyPlus Components
Simple Components
 input; initialize; calculate; report
Compound Components
 assembled from multiple simple
components
 simulated sequentially with overall control
Complex Components
 component may be a system
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EnergyPlus Nodes
 A node is the point at
which a component,
such as a source or a
load, is connected to
the system.
CHWR
Chiller
CHWS
Nodes
Load
CHWR
CHWS
Nodes
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EnergyPlus Nodes (cont’d)
Nodes connect components in HVAC
network
Store network state data

temperature, humidity, flow rate, pressure
(air only) at current barometric pressure
Also store control information: set
points
Store component input and output data
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Example Node Diagram
2
1
5
6
7
8
Return Fan
9
4
3
8
2
Mixed Air System
Manager
7
MA Damper
3
10
2
12
3
4
5
6
Heat Recovery
6
11
1
13
7
Desiccant Wheel
9
8
Supply Fan
9
Zone
10
12
Splitter
10
11
Heating Coil
12
13
Cooling Coil
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EnergyPlus Nodes (cont’d)
Components have one or more pairs of
inlet/outlet nodes


Fan: Air inlet node, Air outlet node
CHW Coil: Air inlet node, Air outlet node,
CHW inlet node, CHW outlet node
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EnergyPlus Nodes (cont’d)
Components read inlet node data and
write outlet node data
Most components “know” nothing more
than their respective input specifications
and inlet/outlet node data
Each zone has a single node for the
zone air conditions
Node data available for output reporting
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Node List
In some cases, a single node or a list of
nodes may be appropriate input
Node List allows user to specify a
variable length list of nodes as input
Name is then referenced elsewhere in
the input file
NODE LIST,
Zone1Inlets,
!- Node List Name
Zone 1 Reheat Air Outlet Node, !- Node Name 1
Zone 1 Fan Coil Outlet Node;
!- Node Name 2
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Branch and Node Details
Output File
*.bnd output file
Details about branches, nodes, and
other elements of the flow connections
Intended for use in debugging potential
problems
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BND File – Node Lists
! #Nodes,<Number of Unique Nodes>
#Nodes,72
! <NodeNumber>,<Node Name>,<# Times Node Referenced After Definition>
1,ZONE 1 INLET NODE,2
2,ZONE 2 INLET NODE,2
===============================================================
Suspicious nodes have 0 references. It is normal for some nodes,
however.
Listing nodes with 0 references (culled from previous list):
! <NodeNumber>,<Node Name>,<# Times Node Referenced After Definition>
65,ZONE 1 NODE,0
67,ZONE 2 NODE,0
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BND File – Branch Lists
! <#Branch Lists>,<Number of Branch Lists>
#Branch Lists,7
! <Branch List>,<Branch List Count>,<Branch List Name>,<Loop
Name>,<Loop Type>
! <#Branches on Branch List>,<Number of Branches>
! <Branch>,<Branch Count>,<Branch Name>,<Loop Name>
! <Branch Inlet/Outlet Nodes>,<Branch Inlet Node Name>,<Branch Outlet
Node Name>
Branch List,1,AIR LOOP BRANCHES,TYPICAL TERMINAL REHEAT 1,Air
#Branches on Branch List,1
..Branch,1,AIR LOOP MAIN BRANCH,TYPICAL TERMINAL REHEAT 1
....Branch Inlet/Outlet Nodes,AIR LOOP INLET NODE,AIR LOOP OUTLET NODE
Branch List,2,COOLING SUPPLY SIDE BRANCHES,CHILLED WATER LOOP,Plant
Supply
#Branches on Branch List,6
..Branch,1,CW PUMP BRANCH,CHILLED WATER LOOP
....Branch Inlet/Outlet Nodes,CW SUPPLY INLET NODE,CW PUMP OUTLET NODE
..Branch,2,LITTLE CHILLER BRANCH,CHILLED WATER LOOP
....Branch Inlet/Outlet Nodes,LITTLE CHILLER INLET NODE,LITTLE CHILLER
OUTLET NODE
34
BND File – Supply Air Paths
! <#Supply Air Paths>,<Number of Supply Air Paths>
#Supply Air Paths,1
! <Supply Air Path>,<Supply Air Path Count>,<Supply Air Path Name>
! <#Components on Supply Air Path>,<Number of Components>
! <Component>,<Component Count>,<Component Type>,<Component Name>
Supply Air Path,1,TERMREHEATSUPPLYPATH
#Components on Supply Air Path,1
Component,1,ZONE SPLITTER,ZONE SUPPLY AIR SPLITTER
! <#Nodes on Supply Air Path>,<Number of Nodes>
! <Node>,<Node Count>,<Node Name>
#Nodes on Supply Air Path,4
Inlet Node,1,ZONE EQUIPMENT INLET NODE
Outlet Node,2,ZONE 1 INLET NODE
Outlet Node,3,ZONE 2 INLET NODE
Outlet Node,4,ZONE 3 INLET NODE
35
BND File – Return Air Paths
! <#Return Air Paths>,<Number of Return Air Paths>
#Return Air Paths,1
! <Return Air Path>,<Return Air Path Count>,<Return Air Path Name>
! <#Components on Return Air Path>,<Number of Components>
! <Component>,<Component Count>,<Component Type>,<Component Name>
Return Air Path,1,TERMREHEATRETURNPATH
#Components on Return Air Path,1
Component,1,ZONE MIXER,ZONE RETURN AIR MIXER
! <#Nodes on Return Air Path>,<Number of Nodes>
! <Node>,<Node Count>,<Node Name>
#Nodes on Return Air Path,4
Outlet Node,1,RETURN AIR MIXER OUTLET
Inlet Node,2,ZONE 1 OUTLET NODE
Inlet Node,3,ZONE 2 OUTLET NODE
Inlet Node,4,ZONE 3 OUTLET NODE
36
BND File – Component Sets
! <#Component Sets>,<Number of Component Sets>
#Component Sets,34
! <Component Set>,<Component Set Count>,<Parent Object Type>,<Parent
Object Name>,<Component Type>,<Component Name>,<Inlet Node
ID>,<Outlet Node ID>,<Description>
Component Set,1,BRANCH,AIR LOOP MAIN
BRANCH,FAN:SIMPLE:CONSTVOLUME,SUPPLY FAN 1,AIR LOOP INLET
NODE,COOLING COIL AIR INLET NODE,Air Nodes
Component Set,2,BRANCH,AIR LOOP MAIN
BRANCH,COIL:WATER:DETAILEDFLATCOOLING,DETAILED COOLING COIL,COOLING
COIL AIR INLET NODE,AIR LOOP OUTLET NODE,Air Nodes
37
BND File – Air Loops
! <#Primary Air Loops>,<Number of Primary Air Loops>
#Primary Air Loops,1
! <Air Loop Connections>,<Air Loop Name>,<# Return Nodes>,<# Supply
Nodes>,<# Zones Cooled>,<# Zones Heated>,<Outside Air Used>
! <Return Connections>,<Zn Eqp Return Node #>,<Zn Eqp Return Node
Name>,<Air Loop Return Node #>,<Air Loop Return Node Name>
! <Supply Connections>,<Zn Eqp Supply Node #>,<Zn Eqp Supply Node
Name>,<Air Loop Supply Node #>,<Air Loop Supply Node Name>
! <Cooled Zone Info>,<Cooled Zone Name>,<Cooled Zone Inlet Node
#>,<Cooled Zone Inlet Node Name>
! <Heated Zone Info>,<Heated Zone Name>,<Heated Zone Inlet Node
#>,<Heated Zone Inlet Node Name>
! <Outside Air (OA)>,<OA Inlet Node #>,<OA Return Air Inlet Node
Name>,<OA Outlet Node #>,OA Mixed Air Outlet Node Name>
Air Loop,TYPICAL TERMINAL REHEAT 1,1,1,3,0,No
Return Node #1,72,RETURN AIR MIXER OUTLET,5,AIR LOOP INLET NODE
Supply Node #1,71,ZONE EQUIPMENT INLET NODE,4,AIR LOOP OUTLET NODE
Cooled Zone #1,RESISTIVE ZONE,1,ZONE 1 INLET NODE
Cooled Zone #2,EAST ZONE,2,ZONE 2 INLET NODE
Cooled Zone #3,NORTH ZONE,3,ZONE 3 INLET NODE
38
BND File –
Plant Loops
! <# Plant Loops>,<Number of Plant Loops>
#Plant Loops,2
! <Plant Loop>,<Plant Loop Name>,<Loop Type>,<Inlet Node Name>,<Outlet
Node Name>,<Branch List>,<Connector List>
Plant Loop,CHILLED WATER LOOP,Supply,CW SUPPLY INLET NODE,CW SUPPLY
OUTLET NODE,COOLING SUPPLY SIDE BRANCHES,COOLING SUPPLY SIDE
CONNECTORS
Plant Loop,CHILLED WATER LOOP,Demand,CW DEMAND INLET NODE,CW DEMAND
OUTLET NODE,COOLING DEMAND SIDE BRANCHES,COOLING DEMAND SIDE
CONNECTORS
Plant Loop,HOT WATER LOOP,Supply,HW SUPPLY INLET NODE,HW SUPPLY OUTLET
NODE,HEATING SUPPLY SIDE BRANCHES,HEATING SUPPLY SIDE CONNECTORS
Plant Loop,HOT WATER LOOP,Demand,HW DEMAND INLET NODE,HW DEMAND OUTLET
NODE,HEATING DEMAND SIDE BRANCHES,HEATING DEMAND SIDE CONNECTORS
39
BND File – Condenser and
Heat Recovery Loops
! <# Condenser Loops>,<Number of Condenser Loops>
#Condenser Loops,1
! <Condenser Loop>,<Condenser Loop Name>,<Loop Type>,<Inlet Node
Name>,<Outlet Node Name>,<Branch List>,<Connector List>
Cond Loop,CHILLED WATER CONDENSER LOOP,Supply,CONDENSER SUPPLY INLET
NODE,CONDENSER SUPPLY OUTLET NODE,CONDENSER SUPPLY SIDE
BRANCHES,CONDENSER SUPPLY SIDE CONNECTORS
Cond Loop,CHILLED WATER CONDENSER LOOP,Demand,CONDENSER DEMAND INLET
NODE,CONDENSER DEMAND OUTLET NODE,CONDENSER DEMAND SIDE
BRANCHES,CONDENSER DEMAND SIDE CONNECTORS
===============================================================
! <# Heat Recovery Loops>,<Number of Heat Recovery Loops>
#Heat Recovery Loops,0
! <Heat Recovery Loop>,<Heat Recovery Loop Name>,<Component
Type>,<Component Name>
40
BND File – Controlled Zones
! <# Controlled Zones>,<Number of Controlled Zones>
#Controlled Zones,3
! <Controlled Zone>,<Controlled Zone Name>,<Equip List Name>,<Control
List Name>,<Zone Node Name>,<Return Air Node Name>,<# Inlet
Nodes>,<# Exhaust Nodes>
! <Controlled Zone Inlet>,<Inlet Node Count>,<Supply Air Inlet Node
Name>,<SD Sys:Cooling/Heating [DD:Cooling] Inlet Node Name>,<DD
Sys:Heating Inlet Node Name>
! <Controlled Zone Exhaust>,<Exhaust Node Count>,<Exhaust Air Node
Name>
Controlled Zone,RESISTIVE ZONE,ZONE1EQUIPMENT,,ZONE 1 NODE,ZONE 1
OUTLET NODE,1,0
Controlled Zone Inlet,1,ZONE 1 INLET NODE,ZONE 1 INLET NODE,N/A
Controlled Zone,EAST ZONE,ZONE2EQUIPMENT,,ZONE 2 NODE,ZONE 2 OUTLET
NODE,1,0
Controlled Zone Inlet,1,ZONE 2 INLET NODE,ZONE 2 INLET NODE,N/A
Controlled Zone,NORTH ZONE,ZONE3EQUIPMENT,,ZONE 3 NODE,ZONE 3 OUTLET
NODE,1,0
Controlled Zone Inlet,1,ZONE 3 INLET NODE,ZONE 3 INLET NODE,N/A
41
Examples of EnergyPlus HVAC
Diagrams with Loops, Branches,
Components, and Nodes
Simplified Plant Node and
Equipment Diagram
Typical Plant & Condenser Loop
Plant Supply Side
Cond Supply Side Loop
Pump
2 Mix
-Cond
3 Splitter
Cond Pump
Purchased
Heating/
Cooling
Towers, Wells, Etc.
Heating or Cooling
Equipment
3 Mixer
Cooling T ower
2 Split
-Cond
Cond De m and Side Loop
43
Example System
44
Non-Conventional Cooling Options
Outside Air
Supply Fan
Connect the Cooling
Tower Directly to the
Cooling Coil
CW Pump
CC
Bypas
s
Bypass
Mixed Outside
Air Box
Relief Air
Cooling
Tower
East
Zone
North
Zone
Zone Air Splitter
Return Air Mixer
Resistive
Zone
Cooling
Tower
Pump
Bypas
s
Connect the Cooling
Tower Directly to the
Radiant Slab. This would
limit the possibility of
Condensation in the Zone
or "Indoor Rain"
45
Low Intensity Radiant Floor Slab &
Conventional Cooling
Outside Air
Supply Fan
CW Pump
Plant Supply Side
Cooling Loop
CC Plant Demand Side
Cooling Loop
Bypass
Mixed Outside
Air Box
Bypass
Chiller
Relief Air
Condenser
Bypass
East
Zone
Zone Air Splitter
Return Air Mixer
Resistive
Zone
Cond Demand Side Loop
Boiler
Cond Pump
Pump
Condenser
Bypass
Plant Supply Side
Heating Loop
North
Zone
Cooling Tower
Bypass
Cond Supply Side Loop
46
Summary
 EnergyPlus uses a loop-node concept to
describe primary and secondary systems
 Six main loop types:



Air Loop and Zone Equipment Loops
Plant Supply and Demand Loops
Condenser Supply and Demand Loops
 Loops are constructed of branches
 Branches contain components in series
 Nodes exist at the beginning and ending of
each branch as well as between components
47