HVAC Air-Side Control Coordination to Reduce Fan Energy Waste
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Solution Overview
Problem
HVAC systems face inefficiencies due to separate control of supply air fans and chilled beam fans, leading to unnecessary operation and increased energy consumption when pressure in the primary air casing varies, even when chilled beam fans are under reduced load or not in use.
Innovation Solution
A method and apparatus for coordinating control between supply air fans and chilled beam fans through a linking controller, allowing for independent or linked operational modes based on fan speed signals, which can reduce fan speeds or shut down components when not needed, thereby optimizing energy use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If separate control of supply air fan and chilled beam fan is used, then each fan can be controlled independently according to its own requirements, but unnecessary operation of supply air fan occurs when chilled beam fans are under reduced load or not in use, leading to increased energy consumption
Solution Approach 1:
The patent combines the control of supply air fan and chilled beam fan into a unified control system. The supply air fan controller receives signals from both the pressure control loop (maintaining primary air casing pressure) and the chilled beam fan control loop. When chilled beam fans are operating at reduced load or are off, the unified controller coordinates to reduce or shut down the supply air fan, eliminating unnecessary energy consumption while maintaining system controllability.
2Reliability
If supply air fan runs at higher speeds to maintain pressure in primary air casing, then pressure control setpoint is maintained, but fans continue to run longer and at higher speeds than necessary when chilled beam fans are not required
Solution Approach 1:
The patent implements dynamic coordination between fan operations. The supply air fan speed is dynamically adjusted based on the operational state of chilled beam fans. When chilled beam fans are running at full speed, the supply air fan maintains higher speed to ensure proper pressure and airflow. When chilled beam fans are at reduced load or off, the supply air fan dynamically reduces its speed or shuts down, optimizing system efficiency while maintaining pressure control stability through the unified controller.
3Loss of energy
If linked control mode is implemented, then unnecessary operation of fans is avoided, but control system complexity increases with multiple operational modes and coordination requirements
Solution Approach 1:
The patent segments the control system into distinct operational modes (independent mode, first linked mode, second linked mode) that can be selectively activated. This segmentation allows the system to simplify control logic within each mode while providing comprehensive coordination across modes. The controller determines which mode to activate based on system conditions, such as whether chilled beam fans are operating, thereby reducing unnecessary fan operation without overwhelming complexity through structured mode-based control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This coordinated control approach reduces unnecessary operation of HVAC system components, leading to lower energy consumption and improved efficiency by ensuring that fans and heat exchange components only operate when necessary.
Implementation Method 1
A heat recovery wheel may intersect both the return and supply sides and may cool and/or dehumidify the inlet air
Implementation Method 2
CBs are pipes or other structures filled with a chilled cooling medium, such as water, which courses therethrough
Implementation Method 3
The SAF pushes air across the coil and through a primary air (PA) casing, and to the facility
Implementation Method 4
the AHU includes a heat pump and a return air fan (RAF), which induces air to move from the facility to an exhaust
Data Source
AI summary
A method and apparatus for controlling an HVAC system. The method may include receiving a fan speed signal from a fan control loop, and choosing among an independent mode, a first linked mode, and a second linked mode, depending on the fan speed signal. The method may also include providing a signal to a pressure control loop to reduce a speed of a supply air fan of an AHU, when the first linked mode is chosen. The method may further include providing a signal to a temperature control loop to decrease a speed of a heat exchange wheel, to decrease a flow rate of a heat exchange fluid to an evaporator coil, or both, when the second linked mode is chosen. The method may additionally include allowing the fan control loop to operate independently of the temperature and pressure control loops, when the independent mode is chosen.