Air Handling Unit Static Pressure Control Using System Effect Curve
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Solution Overview
Problem
Current HVAC systems lack an efficient mechanism to determine and maintain an effective static pressure setpoint for air handling units (AHUs), leading to inefficiencies and increased time for technicians to manually adjust settings, which results in suboptimal performance and energy losses.
Innovation Solution
A method and system that utilize airflow setpoint values from VAV units to determine a combined airflow setpoint, calculate an effective static pressure setpoint based on a system effect curve, and automatically adjust fan speed to operate the AHU at this setpoint, monitoring damper positions to identify and address starving units, thereby optimizing airflow and reducing energy losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a technician manually checks each part of the HVAC system to determine losses, then the technician can identify defects, but the process is time-consuming and labor-intensive
Solution Approach 1:
The patent replaces manual mechanical inspection with an automated electronic system that uses sensors, processors, and communication networks to automatically measure airflow, calculate losses, and identify defects in the HVAC system, eliminating the need for manual technician inspection
Solution Approach 2:
The HVAC system performs self-diagnosis and self-measurement of airflow and losses through integrated sensors and controllers that automatically monitor system performance and communicate defect information without requiring external technician intervention
2Ease of operation
If the static pressure setpoint is kept at a constant value, then the AHU operation is simplified, but the system does not follow the system resistance curve and operates inefficiently
Solution Approach 1:
The patent implements dynamic static pressure setpoint adjustment where the setpoint automatically varies based on real-time measurements of airflow and system resistance, allowing the AHU to follow the system resistance curve and operate efficiently under different loading conditions while maintaining automated control
Solution Approach 2:
The system uses feedback from airflow sensors and pressure measurements to continuously adjust the static pressure setpoint, creating a closed-loop control system that automatically optimizes AHU performance based on actual system conditions rather than relying on fixed predetermined values
3Adaptability or versatility
If the trim and respond method is used to reset static pressure, then the static pressure setpoint can be adjusted, but the method is inefficient due to randomly changing static pressure that does not follow the system impedance curve
Solution Approach 1:
The patent replaces the manual trim and respond method with an automated electronic system that calculates the optimal static pressure setpoint based on measured airflow and system resistance characteristics, ensuring adjustments follow the system impedance curve rather than random changes
Solution Approach 2:
The system introduces an intermediary computational layer that processes airflow measurements and system resistance data to determine the appropriate static pressure setpoint, acting as a mediator between system conditions and control actions to achieve efficient operation
Data Source
AI summary
A system and a method for operating an air handling unit (AHU) at an effective static pressure setpoint in a HVAC system. The method includes receiving airflow setpoint values from each of a plurality of variable air volume (VAV) units to determine a combined airflow set point for the plurality of VAV units of an air handling unit (AHU). The method also includes determining an effective static pressure setpoint for the AHU based on a relation between the combined airflow setpoint value and a static pressure represented by a system effect curve.