Rooftop HVAC Fan and Damper Control for Humidity and CO2
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Solution Overview
Problem
Existing single-zone rooftop air conditioning units lack energy-saving features and are not equipped to efficiently vary airflow during different operating modes, leading to increased energy consumption and comfort issues due to excessive fan operation and humidity levels.
Innovation Solution
A control system that adjusts the speed of the fan drive motor based on operating modes, humidity, and CO2 levels, using a power supply and control circuits to detect temperature and CO2 concentrations, and incorporates automatic control dampers to manage airflow and suction pressure, allowing for energy-efficient operation without modifying existing thermostats or refrigerant systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional single-zone rooftop air conditioning units operate with fixed fan speed, then the system maintains basic cooling function, but energy consumption increases and comfort deteriorates due to excessive fan operation and humidity levels
Solution Approach 1:
The patent applies dynamics by transitioning from fixed fan speed to variable fan speed control. The fan motor speed is dynamically adjusted based on real-time sensing of temperature, humidity, and CO2 levels, allowing the system to adapt to varying operational conditions and occupancy patterns, thereby reducing energy consumption while maintaining comfort and air quality
Solution Approach 2:
The patent implements feedback control through sensors that continuously monitor temperature, humidity, and CO2 levels. This feedback information is used by the control system to adjust fan speed dynamically, creating a closed-loop control system that optimizes energy consumption while maintaining reliable comfort and air quality standards
2Object-affected harmful factors
If fan speed is increased to improve air circulation and reduce humidity, then air quality improves, but energy consumption and noise increase
Solution Approach 1:
The patent applies parameter changes by adjusting fan speed based on measured humidity and temperature conditions. Rather than operating at constant high speed, the fan speed is modulated according to actual environmental parameters, achieving effective humidity control and air quality improvement only when necessary, thereby reducing overall energy consumption
3Object-affected harmful factors
If fan speed is increased to improve air circulation, then air quality improves, but noise increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting fan speed based on actual air quality needs rather than operating at constant high speed. This modulates noise levels to match the actual ventilation requirements, reducing noise pollution while maintaining adequate air quality
4Device complexity
If conventional controls are used without modification, then system simplicity is maintained, but energy-saving capabilities are limited
Solution Approach 1:
The patent introduces an intermediary control system that sits between the existing conventional controls and the fan motor. This intermediary layer adds intelligence and energy-saving capabilities through variable speed control and sensor-based adjustments without requiring complete replacement of the existing control infrastructure, thus balancing added functionality with manageable complexity
Data Source
AI summary
An energy saving air quality control system modulates supply fan speed by use of controlled, variable-frequency drive controls for automatic dampers or suction pressure to maintain adequate air flow across the evaporator coil at partial cooling loads. Indexing the fan speed to maintain the suction pressure of the energized coil controls the maximum relative humidity of the conditioned space. Demand ventilation in the system balances air quality and energy consumption by controlling the outdoor air damper in response to indoor CO2 and humidity levels. The control system variously either (1) produces a variable 0-10 VDC output signal to modulate the outside ventilation air damper as required to keep the CO2 and humidity concentration below a set point; (2) produces a 0 or 24 VAC signal to either open or close a two-position outside air damper for as long a time period as is required in order to keep the CO2 concentration and humidity below a set point; or (3) allows manually setting the outside air damper to provide proper ventilation air at maximum occupancy and maximum air flow and modulates the supply fan speed as required to keep the CO2 concentration and humidity level as measured by a CO2 monitor and leaving air dewpoint temperature below set point.