AHU Fresh Air Damper Control Within Remaining Load Capacity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
HVAC systems face challenges in balancing ventilation rates with energy efficiency and occupant comfort, particularly during conditions that require increased ventilation to reduce pathogen spread, where high ventilation rates can exceed the system's heating and cooling capacity.
Innovation Solution
The method involves determining a fresh air intake damper position for an Air Handling Unit (AHU) to increase ventilation airflow by a fraction based on temperature and air quality factors, utilizing the system's remaining load capacity to maintain comfort conditions while minimizing energy consumption, and forecasting outdoor and indoor conditions to optimize fresh air intake over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the ventilation rate is increased to reduce pathogen spread, then air quality and health safety are improved, but the HVAC system may exceed its heating and cooling capacity to maintain occupant comfort
Solution Approach 1:
The system dynamically adjusts the fresh air intake damper position based on real-time calculations of remaining load capacity, allowing the ventilation rate to vary continuously rather than being fixed. This enables the system to maximize ventilation when capacity allows while maintaining comfort when capacity is constrained.
Solution Approach 2:
The system uses feedback from the HVAC system's current load conditions to determine the appropriate fresh air intake rate. The controller continuously monitors the load capacity and adjusts the damper position accordingly, creating a closed-loop control system that balances ventilation needs with comfort maintenance.
2Object-affected harmful factors
If the ventilation rate is set too high given current indoor and outdoor conditions, then air quality is improved, but the HVAC system lacks the heating and cooling capacity to adequately condition the incoming fresh air while maintaining occupant comfort
Solution Approach 1:
The system performs preliminary calculation of the remaining load capacity before setting the fresh air intake rate. By determining the maximum additional fresh air ventilation that can be admitted and conditioned using the remaining load capacity, the system proactively prevents comfort violations rather than reacting to them.
Solution Approach 2:
The system changes the operational parameters of the HVAC system by adjusting the fresh air intake damper position based on calculated factors. This parameter adjustment optimizes the balance between ventilation rate and conditioning capacity, ensuring that temperature and comfort requirements are met while maximizing fresh air intake.
3Object-affected harmful factors
If the ventilation rate is increased to reduce contaminates, then air quality is improved, but energy costs for conditioning the fresh air increase
Solution Approach 1:
The system applies partial action by admitting only the maximum additional fresh air ventilation that can be conditioned using the remaining load capacity. Rather than maximizing ventilation without regard to energy costs, the system admits precisely the amount of fresh air that can be handled by the available capacity, avoiding excessive energy consumption.
Solution Approach 2:
The system serves itself by automatically determining the optimal fresh air intake rate based on its own remaining load capacity. The controller calculates the factors and adjusts the damper position without external intervention, optimizing energy usage while maintaining adequate ventilation.
4Productivity
If the fresh air intake damper position is adjusted to increase ventilation, then ventilation rate is improved, but the system must balance this against maintaining comfort conditions within the remaining load capacity
Solution Approach 1:
The system replaces complex mechanical control mechanisms with computational algorithms. Rather than using complex mechanical linkages or multiple dampers, the system uses a controller that calculates the remaining load capacity and determines the optimal damper position through software-based factor calculations, simplifying the physical system while maintaining sophisticated control.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A current load on the AHU used to maintain one or more comfort conditions in the building space is determined, along with a remaining load capacity. A maximum additional fresh air ventilation air flow that could be admitted and conditioned using the remaining load capacity of the AHU such that the AHU could still maintain the one or more comfort conditions in the building space is determined. A fresh air intake damper position for the fresh air intake damper that increases the fresh air ventilation air flow through the fresh air intake damper by a fraction of the maximum additional fresh air ventilation air flow is determined. The fraction may be based at least in part on one or more of a temperature factor and an air quality factor. The fresh air intake damper is set to the determined fresh air intake damper position.