Thermal Objects

This section presents an in-depth description of all objects available in SAInt to develop a thermal network model. Figure 1 shows the hierarchy and the parent-child relationships between base objects. Table 1 gives a quick and short description of the base objects. The thermal network consists of two symmetrical sides, known as the hot side and the cold side. For example for a district heating network the hot side (or supply side) delivers heat from the source to the users, while the cold side (or return side) brings the working fluid back to the source. The pipes on both sides have the same characteristics and make a closed loop, resulting in the mass flow rate to be constant between both sides. Only one side is displayed in the SAInt GUI.

For example, the top-level base object in a thermal network model is the "Thermal Network" object TNET. A thermal network contains many other different base objects, such as, heat demands HDEM, cold supply CSUP, or thermal lines TPI. A thermal branch TBR is the parent, and an thermal pipeline TPI is a child. A thermal network object has no parents but only children. A thermal line object TPI cannot be a parent, but only a child. See the schematic below for a visual representation of the complete hierarchical object structure for an thermal network model in SAInt.

Figure 1. Relationship between objects in thermal network. A child object is indicated by the head of a pointed arrow, while a parent is by the tail. Please, open the image in another window of your Internet browser to enlarge it.

Table 1. Icons and descriptions of object types in thermal network model.
ObjType	Display Name	Description
`TNET`	Thermal Network	Models the characteristics and interactions of facilities and/or components of a thermal network. Serves as a container for all objects in the thermal network
`TSUB`	Thermal Sub	Models a subset of nodes, branches, and thermal externals of an thermal network. A thermal sub is branch-oriented, i.e., only thermal branches can be assigned to a thermal sub, and every thermal branch belongs to only one thermal sub
`TZN`	Thermal Zone	Models a subset of nodes, branches, and externals of a thermal network. A thermal zone is node-oriented, i.e., only thermal nodes can be assigned to a thermal zone, and every thermal node belongs to only one thermal zone
`TGRP`	Thermal Group	Models a subset of different objects in a thermal network. Except for the thermal network, subs, and zones, any thermal object can be added to a thermal group. In contrast to thermal subs and zones, thermal groups do not follow any specific assignment rules. Thus, a thermal object can be part of multiple thermal groups
`TNO`	Thermal Node	Models a physical or virtual location in the thermal network where heat (or cold) can be injected or extracted through externals (thermal demand, supply, storage, etc.)
`TPI`	Thermal Pipe	Models the transport of heat (or cold) between two distant locations
`HSUP`	Heat Supply	Models the injection of heat at a node
`HDEM`	Heat Demand	Models the consumption of heat at a node

1. Thermal network (TNET)

A thermal network object is the top parent object in any model of a thermal system in SAInt (Figure 1). A thermal network object is modeled as a directed graph consisting of a set of thermal nodes, branches, and externals that are connected with one another. A thermal network contains a description of all geometric, topological, and relational information, as well as all network child objects and their static and default properties that do not change during the execution of a simulation (e.g., the length and the diameter of a thermal pipe).

The nodes of a thermal network are objects describing a junction among two or more thermal branches and a physical or virtual location in the thermal network where thermal energy (heating or cooling) can be injected or extracted through externals (e.g., demand, supply, etc.).

The branches of a thermal network are objects that establish how nodes and externals are connected and affect the working fluid’s state as it flows through them. These branches are passive objects, such as thermal pipes, that do not inject or extract energy from the system. Branches of a thermal network are thermal pipes.

The externals of a thermal network represent objects injecting or extracting thermal energy (heating or cooling) from the system. Externals of a thermal network are supplies, demands, and storages.

Scenario events define a change in the settings of a thermal network object during the execution of a scenario. Thermal network events can be used to customize the network and simulation settings and to compare the effect of different assumptions across simulation scenarios. The following list describes the scenario events available for a network object.

Summaries for the properties and the events of TNET.

Summary for the derived-result properties of TNET.
Extension	Description	UnitType
PMAX	Maximum value of the pressures of two sides of the nodes	P
TMAX	Maximum value of the temperatures of two sides of the nodes	T
PMIN	Minimum value of the pressures of two sides of the nodes	P
TMIN	Minimum value of the temperatures of two sides of the nodes	T
LOSSC	Total rate of heat transferred from the cold sides of the pipes to the ambient	TQ
FL	Total pressure loss due to friction in the two sides of the pipes	PD
PHI	Total net rate of heat transferred into externals (PHIIN - PHIOUT)	TQ
PHICOMP	Total rate of heat transferred into the heat supply to compensate the heat loss of the pipes and the mismatch between the supplies and the demands	TQ
LOSS	Total rate of heat transferred from the hot sides of the pipes to the ambient	TQ
PHIIN	Total rate of heat transferred into the externals	TQ
PHIOUT	Total rate of heat transferred out of the externals	TQ

Summary for the event-default properties of TNET.
Extension	Description	UnitType
TAMBDEF	Default ambient temperature. The "TAMB" event of TNET, TSUB, or TPI can override it	T

Summary for the event-value properties of TNET.
Extension	Description	UnitType
TAMB	Ambient temperature. The "TAMB" event of TSUB or TPI can override it	T

Summary for the net-input properties of TNET.
Extension	Description	UnitType
PAMB	Ambient pressure	PD
CRSType	Network coordinate reference system for the node locations
Info	Information related to the network model. Any character, including non-alphanumeric, is allowed
PDMIN	Minimum pressure difference between two sides of all the nodes	PD
TimeModified	Time of last network model modification. Updated automatically when changes at network level are saved
Version	Network version. Any character, including non-alphanumeric, is allowed

Summary for the net-read-only properties of TNET.
Extension	Description	UnitType
Name	Name of the network model. Permitted characters are letters, numbers, and underscore ("_"). The name should start with a letter, and have a length of 1 to 30 characters.
NetType	Network Type
NUMBR	Number of branches in the network, sub, zone or group	NO
NUMXT	Number of externals in the network, sub, zone or group	NO
NUMLOOP	Number of closed loops in the network, sub, zone or group	NO
NUMNO	Number of nodes in the network, sub, zone or group	NO
ObjType	Object Type
UID	Unique identifier for the object which cannot be changed during the lifetime of the object
ImageDirectory	Directory path to image file
ModelDir	Directory Path to Model file

Summary for the events of TNET.
Parameter	Type	Description	UnitType
TAMB	Ambient	Ambient temperature. Minimum: 183.15. Maximum: 333.15.	T

2. Thermal network container

The child objects of a network can be grouped into the following subsets, also referred to as "containers": sub, zone, and group. These arrangements can be used to define relevant information for a network, or they can simply be used to conveniently aggregate outputs of a scenario.

2.1. Thermal sub (TSUB)

A sub (also referred to as sub-network or sub-system) is a subset of nodes, branches, and externals of a network. A sub is branch-oriented, i.e., only branches can be assigned to a sub, and every branch belongs to only one sub. The FromNode and ToNode of a branch, as well as the externals connected to these two nodes, are implicitly added to the sub. Thus, nodes connecting branches of different subs and the externals connected to these nodes are always included in multiple subs. But all properties of a sub are determined by the branches belonging to it.

Summaries for the properties and the events of TSUB.

Summary for the derived-result properties of TSUB.
Extension	Description	UnitType
PMAX	Maximum value of the pressures of two sides of the nodes	P
TMAX	Maximum value of the temperatures of two sides of the nodes	T
PMIN	Minimum value of the pressures of two sides of the nodes	P
TMIN	Minimum value of the temperatures of two sides of the nodes	T
LOSSC	Total rate of heat transferred from the cold sides of the pipes to the ambient	TQ
FL	Total pressure loss due to friction in the two sides of the pipes	PD
PHI	Total net rate of heat transferred into externals (PHIIN - PHIOUT)	TQ
PHICOMP	Total rate of heat transferred into the heat supply to compensate the heat loss of the pipes and the mismatch between the supplies and the demands	TQ
LOSS	Total rate of heat transferred from the hot sides of the pipes to the ambient	TQ
PHIIN	Total rate of heat transferred into the externals	TQ
PHIOUT	Total rate of heat transferred out of the externals	TQ

Summary for the event-value properties of TSUB.
Extension	Description	UnitType
TAMB	Ambient temperature. It can override "TNET.TAMB" but can be overridden by "TPI.TAMB"	T

Summary for the net-input properties of TSUB.
Extension	Description	UnitType
Info	Information entered for the object. Any character, including non-alphanumeric, is allowed
Name	Object Name. Permitted characters are letters, numbers, and underscore ("_"). The name should start with a letter, and have a length of 1 to 30 characters. The name should be unique for each object type

Summary for the net-read-only properties of TSUB.
Extension	Description	UnitType
NetType	Network Type
NUMBR	Number of branches in the network, sub, zone or group	NO
NUMXT	Number of externals in the network, sub, zone or group	NO
NUMLOOP	Number of closed loops in the network, sub, zone or group	NO
NUMNO	Number of nodes in the network, sub, zone or group	NO
ObjType	Object Type
UID	Unique identifier for the object which cannot be changed during the lifetime of the object

Summary for the events of TSUB.
Parameter	Type	Description	UnitType
TAMB	Ambient	Ambient temperature. Minimum: 183.15. Maximum: 333.15.	T

2.2. Thermal zone (TZN)

A subset of nodes, branches, and externals of a thermal network. Differently from subs, zones are node-oriented, i.e., only nodes can be assigned to a zone, and every node belongs to one zone. Branches with a FromNode and ToNode belonging to the same zone are implicitly added to the corresponding zone. In contrast, branches with a FromNode and ToNode belonging to two different zones do not belong to any zone. Externals are also implicitly added to the zone of the node they are connected to. But all properties of a zone are determined by the nodes belonging to it.

Intro
derived-result
net-input
net-read-only

Summaries for the properties and the events of TZN.

Summary for the derived-result properties of TZN.
Extension	Description	UnitType
PMAX	Maximum value of the pressures of two sides of the nodes	P
TMAX	Maximum value of the temperatures of two sides of the nodes	T
PMIN	Minimum value of the pressures of two sides of the nodes	P
TMIN	Minimum value of the temperatures of two sides of the nodes	T
LOSSC	Total rate of heat transferred from the cold sides of the pipes to the ambient	TQ
FL	Total pressure loss due to friction in the two sides of the pipes	PD
PHI	Total net rate of heat transferred into externals (PHIIN - PHIOUT)	TQ
PHICOMP	Total rate of heat transferred into the heat supply to compensate the heat loss of the pipes and the mismatch between the supplies and the demands	TQ
LOSS	Total rate of heat transferred from the hot sides of the pipes to the ambient	TQ
PHIIN	Total rate of heat transferred into the externals	TQ
PHIOUT	Total rate of heat transferred out of the externals	TQ

Summary for the net-input properties of TZN.
Extension	Description	UnitType
Info	Information entered for the object. Any character, including non-alphanumeric, is allowed
Name	Object Name. Permitted characters are letters, numbers, and underscore ("_"). The name should start with a letter, and have a length of 1 to 30 characters. The name should be unique for each object type

Summary for the net-read-only properties of TZN.
Extension	Description	UnitType
NetType	Network Type
NUMBR	Number of branches in the network, sub, zone or group	NO
NUMXT	Number of externals in the network, sub, zone or group	NO
NUMLOOP	Number of closed loops in the network, sub, zone or group	NO
NUMNO	Number of nodes in the network, sub, zone or group	NO
ObjType	Object Type
UID	Unique identifier for the object which cannot be changed during the lifetime of the object

2.3. Thermal group (TGRP)

A group is a subset of different child object types (e.g., nodes, branches, externals, etc.) of the whole network. In contrast to subs and zones, groups do not follow any specific assignment rules. Thus, a child object can be assigned to multiple groups, and a group can have as many child objects assigned to it as there are child objects in the network.

Intro
derived-result
net-input
net-read-only

Summaries for the properties and the events of TGRP.

Summary for the derived-result properties of TGRP.
Extension	Description	UnitType
PMAX	Maximum value of the pressures of two sides of the nodes	P
TMAX	Maximum value of the temperatures of two sides of the nodes	T
PMIN	Minimum value of the pressures of two sides of the nodes	P
TMIN	Minimum value of the temperatures of two sides of the nodes	T
LOSSC	Total rate of heat transferred from the cold sides of the pipes to the ambient	TQ
FL	Total pressure loss due to friction in the two sides of the pipes	PD
PHI	Total net rate of heat transferred into externals (PHIIN - PHIOUT)	TQ
PHICOMP	Total rate of heat transferred into the heat supply to compensate the heat loss of the pipes and the mismatch between the supplies and the demands	TQ
LOSS	Total rate of heat transferred from the hot sides of the pipes to the ambient	TQ
PHIIN	Total rate of heat transferred into the externals	TQ
PHIOUT	Total rate of heat transferred out of the externals	TQ

Summary for the net-input properties of TGRP.
Extension	Description	UnitType
Info	Information entered for the object. Any character, including non-alphanumeric, is allowed
Name	Object Name. Permitted characters are letters, numbers, and underscore ("_"). The name should start with a letter, and have a length of 1 to 30 characters. The name should be unique for each object type

Summary for the net-read-only properties of TGRP.
Extension	Description	UnitType
NetType	Network Type
NUMCNSTR	Number of branches in the network, sub, zone or group	NO
NUMBR	Number of branches in the network, sub, zone or group	NO
NUMXT	Number of externals in the network, sub, zone or group	NO
NUMLOOP	Number of closed loops in the network, sub, zone or group	NO
NUMNO	Number of nodes in the network, sub, zone or group	NO
ObjType	Object Type
UID	Unique identifier for the object which cannot be changed during the lifetime of the object

3. Thermal node (TNO)

Nodes represent objects describing a junction among two or more thermal branches, as well as a location in the thermal network where thermal energy can be injected or extracted through externals (e.g., heat demand, cold supply, etc.).

Summaries for the properties and the events of TNO.

Summary for the base-result properties of TNO.
Extension	Description	UnitType
PC	Pressure of the cold side	P
TC	Temperature of the flows out of the cold side	T
PH	Pressure of the hot side	P
TH	Temperature of the flows out of the hot side	T
State	Current operating state of object. Permitted states are ON and OFF. When referred to a node, all externals connected to the node inherit the state

Summary for the derived-result properties of TNO.
Extension	Description	UnitType
PHI	Total net rate of heat transferred into externals (PHIIN - PHIOUT)	TQ
PHIIN	Total rate of heat transferred into externals	TQ
Q	Total flow from the cold side to the hot side via externals	MDOT
PHIOUT	Total rate of heat transferred out of externals	TQ
PD	Pressure difference between the hot side and the cold side ("PH" - "PC")	PD

Summary for the event-default properties of TNO.
Extension	Description	UnitType
PMAXDEF	Default maximum pressure of the hot side and the cold side	P
PMINDEF	Default minimum pressure of the hot side and the cold side	P

Summary for the event-value properties of TNO.
Extension	Description	UnitType
PMAX	Maximum pressure of the hot side and the cold side	P
PMIN	Minimum pressure of the hot side and the cold side	P
PSET	Pressure set-point for the hot side. There should only be one such event in each isolated network	P

Summary for the net-input properties of TNO.
Extension	Description	UnitType
Alias	Alternative object name. Any character, including non-alphanumeric, is allowed
H	Elevation	H
Info	Information entered for the object. Any character, including non-alphanumeric, is allowed
InService	Indicates if an object is considered or disregarded in the execution of a scenario. Externals connected to the node inherit the "inService" status of the node
Name	Object Name. Permitted characters are letters, numbers, and underscore ("_"). The name should start with a letter, and have a length of 1 to 30 characters. The name should be unique for each object type
Visible	If true, the object symbol will be visible in maps	NO
X	Cartesian X coordinate for visualizing the node in the map. Externals assigned to the node are not displayed	XY
Y	Cartesian Y coordinate for visualizing the node in the map. Externals assigned to the node are not displayed	XY
ZoneName	ZoneName of the zone the node belongs to

Summary for the net-read-only properties of TNO.
Extension	Description	UnitType
NetType	Network Type
ID	Object Identification
ObjType	Object Type
UID	Unique identifier for the object which cannot be changed during the lifetime of the object
Degree	Number of connected branches and externals

Summary for the events of TNO.
Parameter	Type	Description	UnitType
PMAX	Constraint	Maximum pressure of both sides. Minimum: 0.0.	P
PMIN	Constraint	Minimum pressure of both sides. Minimum: 0.0.	P
PSET	ControlSetPoint	Pressure of the hot side. Minimum: 0.0.	P

The injection/extraction of water is not considered for now.

4. Thermal branch (TBR)

A branch is a general type of object which describes a generic connection between two nodes in the network. Different types of branches exist in SAInt and the following sections provides more details on each of them.

4.1. Thermal pipe (TPI)

The thermal pipe transports thermal energy via a working fluid from one place to another. A pipe object represents both the pipe on the hot side and the corresponding pipe on the cold side. The direction of such two pipes are the same. The following two images mainly illustrate the branch direction, the flow directions, and temperatures of a thermal pipe.

Figure 2. Illustration of a thermal network with one supply, one pipe and one demand.

Figure 3. Illustration of the thermal network with one supply, one pipe and one demand. The branch direction of the pipe is reversed.

The parameters and events of the pipe on the cold side are the same as its counterpart on the hot side.

Summaries for the properties and the events of TPI.

Summary for the base-result properties of TPI.
Extension	Description	UnitType
TDC	Downstream temperature of the cold side	T
TDH	Downstream temperature of the hot side	T
State	Current operating state of object. Permitted states are ON and OFF. When referred to a node, all externals connected to the node inherit the state
Q	Mass flow rate of the hot side	MDOT

Summary for the derived-result properties of TPI.
Extension	Description	UnitType
PIC	Pressure of the cold side ("PC") of the "from" node	P
TIC	Temperature of the code side ("TC") of the "from" node	T
LOSSC	Heat transferred from the cold side to the ambient	TQ
POC	Pressure of the cold side ("PC") of the "to" node	P
TOC	Temperature of the cold side ("TC") of the "to" node	T
PDC	Pressure difference between the nodes of the cold side in the branch direction ("PIC" - "POC")	PD
TDROPC	Temperature drop on the cold side of the pipe in the flow direction	TD
TUC	Upstream temperature of the cold side based on the flow direction	T
V	Flow velocity of the hot side	VEL
FL	Pressure loss due to friction in the two sides	PD
PI	Pressure of the hot side ("PH") of the "from" node	P
TIH	Temperature of the hot side ("TH") of the "from" node	T
LOSS	Heat transferred from the hot side to the ambient	TQ
PO	Pressure of the hot side ("PH") of the "to" node	P
TOH	Temperature of the hot side ("TH") of the "to" node	T
PD	Pressure difference between the nodes of the hot side in the branch direction ("PI" - "PO")	PD
TDROPH	Temperature drop on the hot side of the pipe in the flow direction	TD
TUH	Upstream temperature of the hot side based on the flow direction	T
QVOL	Volumetric flow rate of the hot side	QVOL

Summary for the event-value properties of TPI.
Extension	Description	UnitType
TAMB	Ambient temperature. It can override "TAMB" of TNET and "TSUB"	T

Summary for the net-input properties of TPI.
Extension	Description	UnitType
Alias	Alternative object name. Any character, including non-alphanumeric, is allowed
DrawLine	If true, element will be drawn as a straight line and internal points will be neglected	NO
FromName	Name of FromNode
Info	Information entered for the object. Any character, including non-alphanumeric, is allowed
D	Inner pipe diameter or design diameter of non-pipe branches	D
RO	Inner wall roughness of pipeline	RO
InService	Indicates if an object is considered or disregarded in the execution of a scenario. Externals connected to the node inherit the "inService" status of the node
HTCLIN	Linear heat transfer coefficient	HTCLIN
Name	Object Name. Permitted characters are letters, numbers, and underscore ("_"). The name should start with a letter, and have a length of 1 to 30 characters. The name should be unique for each object type
Eff	Pipeline efficiency	ND
L	Pipeline length	L
SubName	Sub the branch belongs to
ToName	Name of ToNode
Visible	If true, the object symbol will be visible in maps	NO

Summary for the net-read-only properties of TPI.
Extension	Description	UnitType
A	Cross sectional area	AREA
LGEO	Length According to Map Coordinates	L
ALPHA	Pipeline inclination	ANGLE
LD	Difference between actual pipeline length and geographic length	L
NetType	Network Type
ID	Object Identification
ObjType	Object Type
UID	Unique identifier for the object which cannot be changed during the lifetime of the object

Summary for the events of TPI.
Parameter	Type	Description	UnitType
TAMB	Ambient	Ambient temperature. Minimum: 183.15. Maximum: 333.15.	T

5. Thermal external (TXT)

A thermal external represents a device or a system that interacts with a thermal node by either consuming or producing thermal energy. It can represent different elements of a thermal network, such as a heat pump, combined power and heat facility, absorption chiller, heat sink, or thermal storage. A thermal external has a single connection to a thermal node, and multiple thermal externals can connect to the same thermal node.

Multiple externals at the same node can connect two sides of a node in parallel, which is illustrated below. Note the details outside the district heating network (indicated by the gray boxes) are not modeled in SAInt. For example, the temperature-related properties, HSUP.PLANT.Q, and HSUP.PLANT.PHI model the left side of the heat exchanger of HSUP.PLANT.

Figure 4. Illustration of a HDEM and a HSUP connecting two sides of the same TNO in parallel.

5.1. Heat demand (HDEM)

A heat demand represents a heat exchanger which connects the hot side of the node to the cold side. The heat demand acts as a heat sink extracting thermal energy from the network for a specific purpose (e.g., household, commercial, industrial, etc.).

Summaries for the properties and the events of HDEM.

Summary for the base-result properties of HDEM.
Extension	Description	UnitType
CTRL	Control mode, which is determined by the events and affects which events are considered	NO
TD	Downstream temperature	T
Q	Mass flow rate from the hot side to the cold side	MDOT
State	Current operating state of object. Permitted states are ON and OFF. When referred to a node, all externals connected to the node inherit the state
PHI	Heat exchanged out of the flow	TQ

Summary for the derived-result properties of HDEM.
Extension	Description	UnitType
TI	Temperature of the flows out of the hot side	T
TO	Temperature of the flows out of the cold side	T
TDROP	Temperature drop between the hot and the cold side in the flow direction	TD
TU	Upstream temperature, which is the temperature of the flows out of the hot side	T

Summary for the event-default properties of HDEM.
Extension	Description	UnitType
QMAXDEF	Default maximum mass flow rate from the hot side to the cold side	MDOT
PHIMAXDEF	Default maximum amount of heat exchanged out of the flow	TQ
TMAXDEF	Default maximum value of the downstream temperature and the upstream temperature	T
TMINDEF	Default minimum value of the downstream temperature and the upstream temperature	T

Summary for the event-value properties of HDEM.
Extension	Description	UnitType
TDSET	Set-point of the downstream temperature	T
QSET	Set-point of the mass flow rate from the hot side to the cold side	MDOT
PHISET	Set-point of exchanged heat	TQ
QMAX	Maximum mass flow rate from the hot side to the cold side	MDOT
PHIMAX	Maximum amount of heat exchanged out of the flow	TQ
TMAX	Maximum value of the downstream temperature and the upstream temperature	T
TMIN	Minimum value of the downstream temperature and the upstream temperature	T

Summary for the net-input properties of HDEM.
Extension	Description	UnitType
Alias	Alternative object name. Any character, including non-alphanumeric, is allowed
Info	Information entered for the object. Any character, including non-alphanumeric, is allowed
InService	Indicates if an object is considered or disregarded in the execution of a scenario. Externals connected to the node inherit the "inService" status of the node
Name	Object Name. Permitted characters are letters, numbers, and underscore ("_"). The name should start with a letter, and have a length of 1 to 30 characters. The name should be unique for each object type
NodeName	Name of node the external is connected to
Visible	If true, the object symbol will be visible in maps	NO

Summary for the net-read-only properties of HDEM.
Extension	Description	UnitType
NetType	Network Type
ID	Object Identification
ObjType	Object Type
UID	Unique identifier for the object which cannot be changed during the lifetime of the object

Summary for the events of HDEM.
Parameter	Type	Description	UnitType
PHIMAX	Constraint	Maximum heat out of the flow. Minimum: 0.0.	TQ
PHISET	ControlSetPoint	Heat out of the flow. Minimum: 0.0.	TQ
QMAX	Constraint	Maximum mass flow rate. Minimum: 0.0.	MDOT
QSET	ControlSetPoint	Mass flow rate. Minimum: 0.0.	MDOT
TDSET	ControlSetPoint	Downstream temperature. Minimum: 273.15.	T
TMAX	Constraint	Maximum temperature of both sides. Minimum: 183.15.	T
TMIN	Constraint	Minimum temperature of both sides. Minimum: 183.15.	T

There is no property for the default values of QMAX, TSET, or PHISET.

Three control modes and their combinations of events of the heat demand are summarized in the following table.

Table 2. Three control modes of the heat demand.
Short Name	Description	TDSET	QSET	PHISET	Implemented
Heat	`TDSET` and `PHISET` are specified. `Phi` will equal `PHISET`.	✓	✗	✓	✓
Flow	`TDSET` and `QSET` are specified.	✓	✓	✗	✓
UndefTemp	`PHISET` and `QSET` are specified. `Phi` will equal `PHISET`. Not common.	✗	✓	✓

The last control mode will be implemented in the future.

There are five invalid combinations of events, which are summarized in the following table. If any demand has one of these combinations, the simulation will not start.

Table 3. Five invalid combinations of events for the heat demand and the reasons.
Short Name	TDSET	QSET	PHISET	Reason
Undef	✗	✗	✗	under-determined
MissFlow	✓	✗	✗	under-determined
MissTempHeat	✗	✗	✓	under-determined
MissTempFlow	✗	✓	✗	under-determined
ExtraFlow	✓	✓	✓	overdetermined

5.2. Heat supply (HSUP)

A heat supply transports flow from the cold side of the node to the hot side. Some heat is exchanged into the flow.

A heat supply represents a heat exchanger which connects the hot side of the node to the cold side. The heat supply acts as a heat source injecting thermal energy to the network from a heat production facility or unit (e.g., combined heat and power (CHP), heat pump, boiler, etc.).

Summaries for the properties and the events of HSUP.

Summary for the base-result properties of HSUP.
Extension	Description	UnitType
CTRL	Control mode, which is determined by the events and affects which events are considered	NO
TD	Downstream temperature	T
PHI	Heat exchanged into the flow	TQ
Q	Mass flow rate from the cold side to the hot side	MDOT
State	Current operating state of object. Permitted states are ON and OFF. When referred to a node, all externals connected to the node inherit the state

Summary for the derived-result properties of HSUP.
Extension	Description	UnitType
TI	Temperature of the flows out of the cold side	T
TO	Temperature of the flows out of the hot side	T
TDROP	Temperature drop between the hot and the cold side in the flow direction	TD
TU	Upstream temperature, which is the temperature of the flows out of the cold side	T

Summary for the event-default properties of HSUP.
Extension	Description	UnitType
QMAXDEF	Default maximum mass flow rate from the cold side to the hot side	MDOT
PHIMAXDEF	Default maximum amount of heat exchanged into the flow	TQ
TMAXDEF	Default maximum value of the downstream temperature and the upstream temperature	T
TMINDEF	Default minimum value of the downstream temperature and the upstream temperature	T

Summary for the event-value properties of HSUP.
Extension	Description	UnitType
PFSET	Absolute participating factor. A positive value means the supply participates in the distributed compensation. Will be scaled down to the relative participating factor based on the sum of all the absolute participating factors	ND
TDSET	Set-point of the downstream temperature	T
QSET	Set-point of the mass flow rate from the cold side to the hot side	MDOT
PHISET	Set-point of exchanged heat	TQ
QMAX	Maximum mass flow rate from the cold side to the hot side	MDOT
PHIMAX	Maximum amount of heat exchanged into the flow	TQ
TMAX	Maximum value of the downstream temperature and the upstream temperature	T
TMIN	Minimum value of the downstream temperature and the upstream temperature	T

Summary for the net-input properties of HSUP.
Extension	Description	UnitType
Alias	Alternative object name. Any character, including non-alphanumeric, is allowed
Info	Information entered for the object. Any character, including non-alphanumeric, is allowed
InService	Indicates if an object is considered or disregarded in the execution of a scenario. Externals connected to the node inherit the "inService" status of the node
Name	Object Name. Permitted characters are letters, numbers, and underscore ("_"). The name should start with a letter, and have a length of 1 to 30 characters. The name should be unique for each object type
NodeName	Name of node the external is connected to
Visible	If true, the object symbol will be visible in maps	NO

Summary for the net-read-only properties of HSUP.
Extension	Description	UnitType
NetType	Network Type
ID	Object Identification
ObjType	Object Type
UID	Unique identifier for the object which cannot be changed during the lifetime of the object

Summary for the events of HSUP.
Parameter	Type	Description	UnitType
PFSET	ControlSetPoint	Absolute participating factor. Minimum: 0.0.	ND
PHIMAX	Constraint	Maximum heat into the flow. Minimum: 0.0.	TQ
PHISET	ControlSetPoint	Heat into the flow. Minimum: 0.0.	TQ
QMAX	Constraint	Maximum mass flow rate. Minimum: 0.0.	MDOT
QSET	ControlSetPoint	Mass flow rate. Minimum: 0.0.	MDOT
TDSET	ControlSetPoint	Downstream temperature. Minimum: 273.15.	T
TMAX	Constraint	Maximum temperature of both sides. Minimum: 183.15.	T
TMIN	Constraint	Minimum temperature of both sides. Minimum: 183.15.	T

There is no property for the default values of TSET, PFSET, and PHISET.

Five control modes and their combinations of events of the heat supply are summarized in the following table.

Table 4. Five control modes of the heat supply.
Short Name	Description	TDSET	PHISET	QSET	PFSET	Implemented
Heat	`TDSET` and `PHISET` are specified. `PHI` will equal `PHISET`.	✓	✓	✗	=0 or ✗	✓
Flow	`TDSET` and `QSET` are specified.	✓	✗	✓	✗	✓
CompHeat	Participate in distributed compensation with unknown `Q`. `PHISET` is zero by default, so `TDSET`, `PHISET`, and `PFSET` are specified.	✓	✓ or ✗	✗	>0	✓
UndefTemp	`QSET` and `PHISET` are specified. Not common.	✗	✓	✓	✗
CompUndefTemp	Participate in distributed compensation with unknown `TD`. `PHISET` is 0 by default, so `QSET`, `PHISET` and `PFSET` are specified. Not common.	✗	✓ or ✗	✓	>0

The last two control modes will be implemented in the future.

At least one heat supply must has non-zero PFSET. Multiple heat supplies with PFSET mean they participate in the distributed compensation together.

There are seven invalid combinations of events, which are summarized in the following table. If any supply has one of these combinations, the simulation will not start.

Table 5. Seven incorrect ways to control the heat supply and the reasons.
Short Name	TDSET	QSET	PHISET	PFSET	Reason
Undef	✗	✗	✗	✗	under-determined
Miss	✓	✗	✗	✗	under-determined
MissTempFlow	✗	✓	✗	✗	under-determined
MissTempHeat	✗	✗	✓	✗	under-determined
MissingTempCompHeat	✗	✗	✓ or ✗	✓	under-determined
ExtraFlow	✓	✓	✓	✗	overdetermined
ExtraFlowComp	✓	✓	✓ or ✗	✓	overdetermined