Reducing microbial growth on packaged terminal air conditioners
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Solution Overview
Problem
Packaged Terminal Air Conditioners (PTACs) face issues with microbial growth due to the presence of water and water vapor, leading to undesirable accumulation of microorganisms like Listeria monocytogenes, Legionella, and others, which can cause unpleasant odors and health problems, and existing solutions are inadequate in maintaining hygiene and extending the time between cleaning procedures.
Innovation Solution
The use of antimicrobial lighting systems with LED elements emitting light within specific wavelength ranges (380-420 nm and 200-280 nm) to inactivate microorganisms on PTAC surfaces, controlled by a lighting array controller that adjusts based on the PTAC's operational status and occupancy to optimize microbial inactivation while minimizing energy consumption and exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional cleaning procedures are used to maintain hygiene in PTACs, then microbial growth is temporarily reduced, but the time between cleaning procedures is limited and operational downtime increases
Solution Approach 1:
The patent replaces mechanical cleaning procedures with a photonic-based antimicrobial lighting system. LED lights emitting in the 380-420 nm and 200-280 nm wavelength ranges are installed within the PTAC to continuously or periodically inactivate microorganisms on surfaces, eliminating the need for manual cleaning interventions and associated operational downtime.
Solution Approach 2:
The antimicrobial lighting system enables continuous microbial inactivation during PTAC operation. The lighting array can operate continuously or on scheduled cycles without requiring the system to shut down for cleaning, maintaining hygiene continuously rather than periodically through intermittent manual intervention.
2Reliability
If antimicrobial lighting is continuously activated to maximize microbial inactivation, then hygiene is improved, but energy consumption increases
Solution Approach 1:
The lighting array controller implements periodic activation of the antimicrobial LED lights based on PTAC operational status. Lights are activated during cooling mode when condensate is present and deactivated during heating mode or when not needed, providing effective microbial control only during high-risk periods and reducing overall energy consumption.
Solution Approach 2:
The system uses feedback from PTAC operational status signals to dynamically control lighting activation. The controller receives status information about cooling/heating modes and adjusts lighting operation accordingly, optimizing the balance between microbial inactivation effectiveness and energy consumption based on real-time conditions.
3Reliability
If antimicrobial light is applied at high irradiance to quickly inactivate microorganisms, then microbial growth is reduced more effectively, but the risk of exposure to harmful UV radiation increases
Solution Approach 1:
The lighting system is divided into separate wavelength segments: violet LEDs emitting in the 380-420 nm range and UV LEDs emitting in the 200-280 nm range. These segments can be activated independently or in combination, allowing selective application of antimicrobial wavelengths while controlling exposure to harmful UV radiation through targeted, localized illumination of internal surfaces.
Solution Approach 2:
The antimicrobial lighting is positioned to illuminate specific target surfaces where microbial growth occurs (evaporator coils, condensate pans, ducts) rather than exposing the entire environment to high irradiance. This localized application delivers effective microbial inactivation at affected surfaces while minimizing overall radiation exposure risk.
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
The antimicrobial lighting effectively reduces microbial growth on PTAC surfaces, improving hygiene, reducing unpleasant odors, and extending the time between cleaning procedures, while ensuring safe and efficient operation.
Implementation Method 1
antimicrobial lighting systems with LED elements emitting light within specific wavelength ranges (380-420 nm and 200-280 nm)
Implementation Method 2
antimicrobial light within one or more antimicrobial wavelength ranges is applied to inactivate one or more microorganisms on target surface(s)
Data Source
AI summary
An antimicrobial lighting system is used to reduce microbial growth on surfaces in or on air conditioning and/or heating equipment. In some examples, antimicrobial light within one or more antimicrobial wavelength ranges is applied to inactivate one or more microorganisms on target surface(s) within or on a packaged terminal air conditioner (PTAC). The antimicrobial light may include light within a first antimicrobial wavelength range and/or light within a second antimicrobial wavelength range. The antimicrobial lighting system may include an array of individually controllable antimicrobial light segments. An array controller may individually control activation of the one or more antimicrobial light segments based on the status information or commands received from a PTAC controller or from an external computing device.