Supply Air Fan
A Supply Air Fan circulates and delivers conditioned air throughout a building. The fan enhances airflow, ensuring that the treated air reaches different zones for effective heating or cooling.
System
Fan Speed Method
Specify how the fan speed varies with Continuous or Discrete options. Discrete offers specific speed settings, while Continuous allows smooth changes up to Design Maximum Air Flow Rate. For power calculation, Discrete uses time-weighted averaging, and Continuous uses flow-weighted averaging. Use Discrete with 1 speed for constant volume or on-off fans. For variable air volume fans, opt for Continuous, requiring a fan performance curve entry in the Electric Power Function of Flow Fraction Curve Name field.
Fan Power Minimum Flow Rate Fraction
Specify the minimum operating level for a variable speed fan with the Fan Power Minimum Flow Rate Fraction. During calculation, this fraction of the Design Maximum Air Flow Rate determines fan power at low flow rates. Note that it doesn't impose a lower limit on airflow during simulation. Ensure the value falls between 0 and 1. This field applies exclusively when the Speed Control Method is set to Continuous.
Fan Motor Efficiency
Specify the Fan Motor Efficiency by entering the motor efficiency value, calculated as the ratio of shaft power to electric power consumed by the motor.
Fan Motor In Air Stream Fraction
Specify the Fan Motor In Air Stream Fraction, representing the fraction of motor heat added to the air stream. This value should range between 0 and 1. A 0 indicates the fan motor is entirely outside the air stream, with no motor heat added. A 1.0 implies the motor is entirely inside the air stream, adding all its heat to it.
Sizing
Fan Design Power Sizing Method
Specify the Fan Design Power Sizing Method:
Power Per Flow: Use Electric Power Per Unit Flow Rate to size Design Electric Power Consumption.
Power Per Flow Per Pressure: Size power based on Electric Power Per Unit Flow Rate Per Unit Pressure.
Total Efficiency And Pressure: Size power using input Fan Total Efficiency and Design Pressure Rise. Adjust based on specific system requirements.
Fan Total Efficiency
Specify the Fan Total Efficiency value, calculated as the ratio of shaft power to the electric power consumed by the motor. Ensure this value accurately represents the overall efficiency of the fan system.
Fan Design Pressure Rise
Specify the Fan Design Pressure Rise, denoting the total system pressure rise experienced by the fan in Pascals at full flow rate. This should be at an altitude-adjusted standard density of dry air, considering 20 degrees Celsius dry bulb temperature. Set this value based on the specific requirements and characteristics of the fan system.
Sizing Method
Specify the Sizing Method:
Autosize: Allow the system to automatically determine the appropriate size based on specified parameters.
Manual: Manually input the sizing parameters according to specific requirements
Fan Design Maximum Air Flow Rate
Specify the Fan Design Maximum Air Flow Rate, representing the design volume flow rate of the fan as installed in the HVAC system, in m3/s. This value, which is the full-speed flow rate, serves as the upper limit for fans capable of varying their flow rate. The input can be autosized to allow the system to automatically determine the appropriate value based on specific parameters.
Fan Design Electric Power Consumption
Specify the Fan Design Electric Power Consumption, denoting the electric power consumption at the full Design Maximum Air Flow Rate and Design Pressure Rise, in Watts. This value is used to determine fan efficiency. The field is autosizable, with options available for the method used to size the design power. The autosizing method can be selected in the following field based on specific system requirements.
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