.Buildings.Air.Systems.SingleZone.VAV.ChillerDXHeatingEconomizer .Buildings.Air.Systems.SingleZone.VAV.ChillerDXHeatingEconomizerThis is a conventional single zone VAV HVAC system model. The system contains a variable speed supply fan, electric heating coil, water-based cooling coil, economizer, and air-cooled chiller. The control of the system is that of conventional VAV heating and cooling. During cooling, the supply air temperature is held constant while the supply air flow is modulated from maximum to minimum according to zone load. This is done by modulating the fan speed. During heating, the supply air flow is held at a constant minimum while the heating coil is modulated accoding to zone load. The mass flow of chilled water through the cooling coil is controlled by a three-way valve to maintain the supply air temperature setpoint during cooling. The mixing box maintains the minimum outside airflow fraction unless conditions for economizer are met, in which case the economizer controller adjusts the outside airflow fraction to meet a mixed air temperature setpoint. The economizer is enabled if the outside air drybulb temperature is lower than the return air temperature and the system is not in heating mode.
There are a number of assumptions in the model. Pressure drops through the system are collected into a single component. The mass flow of return air is equal to the mass flow of supply air. The mass flow of outside air and relief air in the mixing box is ideally controlled so that the supply air is composed of the specified outside airflow fraction, rather than having feedback control of damper positions. The cooling coil is a dry coil model.
| Name | Description |
|---|---|
 MediumA | Medium model for air |
 MediumW | Medium model for water |
out.C.
not use_powerCharacteristic
with the enumeration
Buildings.Fluid.Movers.BaseClasses.Types.HydraulicEfficiencyMethod.
This is for
#2668.
cooCoi.Q_flow_nominal to respect the heat flow convention.