Components
The Components tab displays the information of the components that have been added to a loop. The components will be displayed on a table grouped by the category from the Plant Component Selection Bar: Pumps, Equipment, Thermal Storage, and Heat Exchanger. When expanded, each component will display pertinent information about the selected equipment library member. A different equipment library member can be selected but the library member information cannot be edited on this screen.
All components except for Heat Exchangers and District Cooling/Heating are in the library. To view details on each input field, please go to the equipment library section to view them in more detail.
Heat Exchangers
A fluid-to-fluid heat exchanger is designed to couple the supply side of one plant or condenser loop to the demand side of another plant or condenser loop. This heat exchanger is fairly general and can be configured for use in any application where any two loops need to be connected together. The only constraints are that one side must be connected to the supply side of one loop and the other side connected to the demand side of a different loop. Because the heat exchanger is intended to be generic, its two sides are distinguished by the nature of loop side being connected. One side is called “Loop Supply Side” to indicate the heat exchanger is situated on the supply side of a loop. The other side is called “Loop Demand Side” to indicate it is on the demand side of a loop. The heat exchanger is intended to act as a supply component for the loop connected to it as the “Loop Supply Side” and as a demand component for the loop connected to it as the “Loop Demand Side.” From the point of view of the heat exchanger model itself, the Loop Demand Side fluid serves as the source/sink to supply heating/cooling to the fluid in the Loop Supply Side.
Model Type
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Default value: Ideal
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Min & Max: N/A
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Typical Range: N/A
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Units: N/A
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Description: Below are the selection types for the model.
● Cross Flow Both Unmixed: Specifies a single-pass, cross-flow heat exchanger. The effectiveness will be calculated using a cross-flow heat exchanger correlation for both streams unmixed.
● Cross Flow Both Mixed: Specifies a single-pass, cross-flow heat exchanger. The effectiveness will be calculated using a cross-flow heat exchanger correlation for both streams mixed.
● Cross Flow Supply Mixed Demand Unmixed: Specifies a single-pass, cross-flow heat exchanger. The effectiveness will be calculated using a cross-flow heat exchanger correlation for flow mixed on the Loop Supply side and flow unmixed on the Loop Demand Side.
● Cross Flow Supply Unmixed Demand Mixed: Specifies a single-pass, cross-flow heat exchanger. The effectiveness will be calculated using a cross-flow heat exchanger correlation for flow unmixed on the Loop Supply side and flow mixed on the Loop Demand Side.
● Counter Flow: Specifies a counter-flow shell and tube heat exchanger. The effectiveness will be calculated using a counter-flow shell and tube heat exchanger correlation.
● Parallel Flow: Specifies a parallel-flow shell and tube heat exchanger. The effectiveness will be calculated using a parallel-flow shell and tube heat exchanger correlation.
● Ideal: Specifies an ideal heat exchanger. The effectiveness will be set to ‘1.0’ and the specified UA will be ignored. The heat transfer rate will be calculated as the maximum possible heat transfer rate.
UA Value
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Default value: Autosized
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Min & Max: 0 to no maximum
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Typical Range: 100,000 W/K; 180,000 W/F
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Units: W/K; W/°C; W/°F
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Description: This numerical field is used to specify the overall U-Factor Times Area (UA) for use in the calculation of the heat exchanger effectiveness. If Ideal is specified as the heat exchanger type, the effectiveness will be set to 1.0. When set to autosize Heat Exchanger U-Factor Times Area Value is calculated based on an effectiveness of 1.0 where capacity is such that the temperatures in the plant for the two loops can be maintained.
Control Type
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Default value: For uncontrolled HX – Uncontrolled, For HX with Controls – Cooling Setpoint Modulated, For HX Waterside Economizer – Cooling Setpoint On Off With Component Override
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Min & Max: N/A
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Typical Range: N/A
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Units: N/A
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Description: This field is used to specify how the heat exchanger is to be controlled during operation. Different applications for connecting two loops will require different control behavior and different control options are needed depending on the desired behavior. There are the following eleven key choice options to choose from:
1. For Heat Exchanger Uncontrolled, the options are Uncontrolled, Sequencing with Modulated Flow, Sequencing with Max Flow
2. For Heat Exchanger with Controls, the options are Cooling Setpoint Modulated, Cooling Setpoint On/Off, Dual Deadband Setpoint Modulated, Dual Deadband Setpoint On/Off, Operation Scheme Modulated, Operation Scheme On Off, Heating Setpoint Modulated, Heating Setpoint On/Off and Uncontrolled.
3. For Heat Exchanger with Waterside Economizer, the options are Cooling Differential On Off and Cooling Setpoint On Off With Component Override.
● Uncontrolled - This control mode is applicable to situations where the heat exchanger is passively running all the time and always transfers as much heat as possible between the fluid streams. However there is one aspect of control in that it will only request flow on the Loop Demand Side when there is non-zero flow into the heat exchanger on the Loop Supply Side.
● Operation Scheme Modulated - This control mode is applicable to situations where the heat exchanger is controlled by an operation scheme. When using this control mode the heat exchanger serves as a supply component. The operation scheme will dispatch a load request to the heat exchanger which it will try meet by conditioning the fluid stream connected as the Loop Supply Side. If the heat exchanger could exceed the load request, then the flow through the fluid stream connected as the Loop Demand Side will be modulated to just meet the load request.
● Operation Scheme On Off - This control mode is applicable to situations where the heat exchanger is controlled by an operation. When using this control mode the heat exchanger serves as a supply component. The operation scheme will dispatch a load request to the heat exchanger which it will use as an on/off signal to decide if the heat exchange should run or not. If it runs, it will run at full capacity and may exceed the load request.
● Heating Setpoint Modulated - This control mode is applicable to situations where the Loop Demand Side can provide useful heating to the Loop Supply Side. If the setpoint and inlet temperatures are such that heat exchanger could transfer heat from the Loop Demand Side to the Loop Supply Side to meet the heating setpoint, then the heat exchanger will run. The inlet temperatures must differ by more than the value set in the field called Minimum Temperature Difference to Activate Heat Exchanger for the heat exchanger to operate. If the heat exchanger could overshoot the setpoint, then the flow through the fluid stream connected as the Loop Demand Side will be modulated to just meet the setpoint.
● Heating Setpoint On/Off - This control mode is applicable to situations where the Loop Demand Side can provide useful heating to the Loop Supply Side. If the setpoints and inlet temperatures are such that heat exchanger could transfer heat from the Loop Demand Side to the Loop Supply Side to meet the heating setpoint, then the heat exchanger will run. The inlet temperatures must differ by more than the value set in the field called Minimum Temperature Difference to Activate Heat Exchanger for the heat exchanger to operate. If it runs, it will run at full capacity and may overshoot the setpoint.
● Cooling Setpoint Modulated - This control mode is applicable to situations where the Loop Demand Side can provide useful cooling to the Loop Supply Side. If the setpoints and inlet temperatures are such that heat exchanger could transfer heat from the Loop Supply Side to the Loop Demand Side to meet the cooling setpoint, then the heat exchanger will run. The inlet temperatures must differ by more than the value set in the field called Minimum Temperature Difference to Activate Heat Exchanger for the heat exchanger to operate. If the heat exchanger could undershoot the setpoint, then the flow through the fluid stream connected as the Loop Demand Side will be modulated to just meet the setpoint.
● Cooling Setpoint On/Off - This control mode is applicable to situations where the Loop Demand Side can provide useful cooling to the Loop Supply Side. If the setpoints and inlet temperatures are such that heat exchanger could transfer heat from the Loop Supply Side to the Loop Demand Side to meet the cooling setpoint, then the heat exchanger will run. The inlet temperatures must differ by more than the value set in the field called Minimum Temperature Difference to Activate Heat Exchanger for the heat exchanger to operate. If it runs, it will run at full capacity and may undershoot the setpoint.
● Dual Dead band Setpoint Modulated - This control mode is applicable to situations where the Loop Demand Side can provide either useful cooling or heating to the Loop Supply Side. If the setpoints and inlet temperatures are such that heat exchanger could transfer heat from the Loop Demand Side to the Loop Supply Side to meet the lower setpoint, then the heat exchanger will run. If the setpoints and inlet temperatures are such that heat exchanger could transfer heat from the Loop Supply Side to the Loop Demand Side to meet the high setpoint, then the heat exchanger will run. The inlet temperatures must differ by more than the value set in the field called Minimum Temperature Difference to Activate Heat Exchanger for the heat exchanger to operate. If the heat exchanger could overshoot the lower setpoint, or undershoot the higher setpoint, then the flow through the fluid stream connected as the Loop Demand Side will be modulated to just meet the deadband setpoint.
● Dual Dead band Setpoint On/Off - This control mode is applicable to situations where the Loop Demand Side can provide either useful cooling or heating to the Loop Supply Side. If the setpoints and inlet temperatures are such that heat exchanger could transfer heat from the Loop Demand Side to the Loop Supply Side to meet the lower setpoint, then the heat exchanger will run. If the setpoints and inlet temperatures are such that heat exchanger could transfer heat from the Loop Supply Side to the Loop Demand Side to meet the high setpoint, then the heat exchanger will run. The inlet temperatures must differ by more than the value set in the field called Minimum Temperature Difference to Activate Heat Exchanger for the heat exchanger to operate. If the heat exchanger runs, it will run at full capacity and may overshoot the lower setpoint or undershoot the higher setpoint.
● Waterside Economizer based on Differential Temperature - This control mode is applicable to situations where the Loop Demand Side can provide useful cooling to the Loop Supply Side. This mode is similar to Cooling Setpoint On/Off except that it ignores any cooling set point and its control is based only on the temperature difference between Loop Demand Side and the Loop Supply Side. The inlet temperatures must differ by more than the value set in the field called Minimum Temperature Difference to Activate Heat Exchanger for the heat exchanger to operate.
● Waterside Economizer Integrated with Chiller - This control mode is applicable to situations where the heat exchanger operation is integrated with the operation of a specific chiller. Typically the heat exchanger and chiller are in parallel. When conditions are favorable for the heat exchanger to provide cooling to the Loop Supply Side, the heat exchanger is run and the integrated chiller is turned off. When conditions are not favorable, the heat exchanger is completely off and the chiller is allowed to run as usual. If it runs it will run at full capacity and may undershoot the setpoint. The chiller that is integrated with the heat exchanger is identified by entering the name of the chiller. The setpoint and control signal temperatures must differ by more than the value set in the field called Minimum Temperature Difference to Activate Heat Exchanger for the heat exchanger to operate.
Sizing Factor
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Default value: 1.0
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Min & Max: 1 to no maximum
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Typical Range: 1.15 to 1.25
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Units: N/A
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Description: This input field over sizes the heat exchanger to handle any condition.
District Cooling
Centralized source of chilled water, such as a district cooling system.
Nominal Capacity
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Default value: Autosized
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Min & Max: 1 to no maximum
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Typical Range: N/A
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Units: W; kW; tons; Btuh; Mbh
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Description: Contains the nominal demand that the district cooling will meet. This field is autosizable.
Capacity Fraction Schedule Name
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Default value: Available 100%
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Min & Max: N/A
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Typical Range: N/A
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Units: N/A
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Description: This input field contains the name of a schedule that describes how the nominal capacity varies over time. The capacity at a given point in time is determined by the product of the previous field and the value in this schedule.
District Heating
Centralized source of hot water, such as a district heating system.
Nominal Capacity
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Default value: Autosized
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Min & Max: 1 to no maximum
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Typical Range: N/A
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Units: W; kW; tons; Btuh; Mbh
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Description: This numeric field contains the nominal demand that the district heating will meet. This field is autosizable.
Nominal Capacity Modifier
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Default value: Available 100%
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Min & Max: N/A
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Typical Range: N/A
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Units: N/A
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Description: This input field contains the name of a schedule from the Utilization / Multipliers category in the library. It describes how the nominal capacity varies over time. The capacity at a given point in time is determined by the product of the previous field and the value in this schedule.