Method to avoid fan cycling during low ambient operation
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Solution Overview
Problem
HVAC systems experience stress and fatigue in condenser coils due to pressure and temperature fluctuations caused by fan cycling, especially around 'dead tubes' during low ambient temperatures, leading to potential fatigue failure.
Innovation Solution
Implementing a controller system that maintains a non-zero fan speed based on ambient temperature and pressure measurements to prevent drastic pressure changes, ensuring constant liquid pressure and reducing stress on the condenser coils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the fan is cycled on and off during low ambient temperature operation, then energy consumption is reduced, but pressure fluctuations occur in the condenser coil causing stress and fatigue
Solution Approach 1:
The patent applies periodic action by cycling the fan on and off during low ambient temperature operation. The controller monitors ambient temperature and activates the fan only when temperature drops below a predetermined threshold, creating a periodic operation pattern that reduces energy consumption while maintaining system reliability through controlled cycling rather than continuous operation.
Solution Approach 2:
The patent changes the operational parameters of the fan based on ambient temperature conditions. By adjusting the fan's operational state (on/off) according to temperature parameters, the system optimizes energy consumption during low ambient temperature operation while preventing pressure fluctuations that would compromise condenser coil reliability.
2Loss of energy
If the fan speed is reduced during low ambient temperature operation, then energy consumption is reduced, but pressure spikes occur in the condenser coil
Solution Approach 1:
The patent implements dynamics by making the fan speed variable rather than fixed. The controller dynamically adjusts fan speed based on real-time ambient temperature measurements, reducing speed during low temperature operation to save energy while maintaining sufficient rotation to prevent dangerous pressure spikes in the condenser coil.
Solution Approach 2:
The patent employs feedback mechanisms where the controller continuously monitors ambient temperature and uses this information to adjust fan speed accordingly. This closed-loop control ensures that fan speed is optimized for energy efficiency while preventing pressure spikes through real-time adjustments based on environmental conditions.
3Stress or pressure
If the fan is operated continuously at high speed, then pressure stability is maintained in the condenser coil, but energy consumption increases
Solution Approach 1:
The patent applies periodic action by operating the fan at high speed only when necessary (during high ambient temperature operation) and reducing or stopping operation during low temperature periods. This periodic high-speed operation maintains pressure stability when needed while avoiding continuous high energy consumption.
Solution Approach 2:
The patent changes the fan speed parameter dynamically based on ambient temperature conditions. During high temperature operation, the fan operates at high speed to maintain pressure stability; during low temperature operation, the speed is reduced or halted, optimizing the balance between pressure stability and energy consumption.
4Loss of energy
If the fan speed is reduced during low ambient operation, then energy efficiency improves, but stress concentration occurs around dead tubes
Solution Approach 1:
The patent implements dynamics by dynamically adjusting fan speed based on ambient temperature thresholds. During low ambient operation, the fan speed is reduced to improve energy efficiency, while the system accepts controlled stress variations around dead tubes that remain within safe operational limits through dynamic adaptation rather than static high-speed operation.
Solution Approach 2:
The patent changes the operational parameters of the fan system based on environmental conditions. By adjusting fan speed parameters during low ambient temperature operation, the system optimizes energy efficiency while managing structural stress around dead tubes through parameter adaptation rather than maintaining constant high-speed operation.
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 approach reduces stress on the condenser coils, increases efficiency, and extends component life by maintaining consistent pressures, thereby minimizing fatigue and strain.
Implementation Method 1
a plurality of fans configured to provide airflow across the plurality of tubes
Implementation Method 2
the controller further configured to associate a measured temperature with a predetermined fan speed and to direct the fan to spin at a rate greater than or equal to the predetermined fan speed when the measured temperature is less than a predetermined temperature
Data Source
AI summary
A system based on temperature and/or pressure switches connected to a fan controller. An HVAC circuit includes at least one condenser coil with a plurality of tubes, one or more stages coupled to one or more compressors, at least one temperature sensor, at least one fan configured to provide airflow across the plurality of tubes, and a controller. Instead of cycling the fan off and on, fans associated with the condenser are kept running at a low speed.