Chilled Water Loop
A chilled water loop comprises chillers, pumps, pipes, control devices, and cooling coils. Cool water is generated by the chillers, distributed by the pumps, and passed through the cooling coils and the whole 'loop' is controlled by setpoints managers and plant equipment operation schemes.
The following chilled water loop types are available:
System
Design Loop Exit Temp.
Specify the Design Loop Exit Temperature by setting the water temperature in degrees Celsius at the exit of the supply side of the plant loop.
Design Loop Temp. Difference
Specify the Design Loop Temperature Difference, representing the design temperature rises (for cooling or condenser loops) or falls (for heating loops) in degrees Celsius across the demand side of a plant loop. Component models utilize this temperature difference to determine the flow rates required to meet design capacities.
Min. Loop Temp.
Specify the Minimum Loop Temperature by setting the maximum allowable temperature in degrees Celsius for this loop.
Max Loop Temp.
Specify the Maximum Loop Temperature by setting the minimum allowable temperature in degrees Celsius for this loop.
Load Distribution Scheme
Specify the Load Distribution Scheme based on the desired sequencing algorithm for equipment operation to meet the plant loop demand. Options include Optimal, Sequential Load, Uniform Load, Sequential Uniform PLR, and Uniform PLR.
Setpoint Manager
Setpoint Manager Type
Specify the Setpoint Manager Type to define the control strategy for supply-side components on the loop. Choose between Constant (for a fixed hot water supply temperature) or Outdoor Air Reset (which adjusts chilled water supply temperature based on outdoor air temperature).
Setpoint at Outdoor Low Temperature
Specify the Supply Air Temperature Setpoint in degrees Celsius at the outdoor low temperature for the first reset rule when using the Constant Setpoint Manager Type.
Outdoor Low Value
Specify the Outdoor Air Low Temperature in degrees Celsius for the first supply air temperature reset rule when using the Outdoor Air Reset Setpoint Manager Type.
Setpoint at Outdoor High Temperature
Specify the Setpoint at Outdoor High Temperature in degrees Celsius for the first supply air temperature reset rule. This value generally represents the outdoor air temperature at which the supply temperature is at its maximum.
Outdoor High Value
Specify the Outdoor High Value in degrees Celsius for the first supply air temperature reset rule, considering the outdoor air temperature corresponding to the maximum supply temperature. These fields are applicable when the Setpoint Manager Type is Outdoor Air Reset.
Sizing
Sizing Option
Specify the Sizing Option as either Coincident or Non-coincident. Coincident sizing triggers additional iterations of the sizing simulations, using coincident flow rates for each plant loop component to determine the total loop flow rate. Non-coincident sizing means that the plant loop flow rates are the sum of the component flow rates.
Sizing Method
Specify the Sizing Method, choosing from Autosize or Manual. Manual sizing requires completing all numerical fields with valid entries.
Min. Loop Flow Rate
Specify the Min. Loop Flow Rate, indicating the minimum loop flow rate in cubic meters per second.
Max. Loop Flow Rate
Specify the Max. Loop Flow Rate, representing the maximum loop flow rate in cubic meters per second. This parameter is also utilized when autocalculating the loop volume.
Plant Loop Volume
Specify the Plant Loop Volume, indicating the volume of the plant loop in cubic meters (m³). This numeric field contains the loop volume for the entire loop, encompassing both the demand side and the supply side. It is utilized for the loop capacitance calculation. If zero volume is specified, the loop lacks fluid heat capacity. On the other hand, an excessively large capacitance may lead to an unrealistic time delay and a suboptimal response to changes in loop setpoint temperature. The auto-calculate option sets the loop volume to the product of the Maximum Loop Flow Rate and the user input for Loop Circulation Time, with a default value of 2 minutes.
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