PTAC Makeup Air Dehumidification With Secondary Refrigeration
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Solution Overview
Problem
Packaged terminal air conditioning (PTAC) units fail to condition and dehumidify outside makeup air, leading to potential mold and mildew growth in spaces, especially in high humidity areas, as they introduce unconditioned outside air at ambient temperatures and humidity levels, not meeting ASHRAE and local building codes.
Innovation Solution
A secondary refrigeration system is integrated into the PTAC unit, comprising a second evaporator coil to receive outside air for cooling and dehumidification, with a compressor and condenser coil configuration to condition outside air before it enters the space, allowing for separate control of temperature and humidity reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a PTAC unit introduces outside air to meet ASHRAE Standard 90.1 and local building codes, then the ventilation requirement is satisfied, but the outside air introduces high moisture levels that cause mold and mildew growth
Solution Approach 1:
The patent applies preliminary action by conditioning the outside air before it enters the space. The PTAC unit includes an evaporator coil and associated controls that pre-cool and dehumidify the outside air introduced for ventilation, preventing high moisture levels from causing mold and mildew growth while still meeting ASHRAE Standard 90.1 ventilation requirements
2Use of energy by moving object
If a PTAC unit operates with evaporator fan off to reduce energy consumption, then energy savings are achieved, but outside air is drawn into the space creating negative pressure and intermittent unconditioned air intake
Solution Approach 1:
The patent applies self-service by designing the system to automatically manage ventilation and conditioning without requiring the evaporator fan to run continuously. The controls system monitors and manages outside air intake and conditioning, ensuring proper ventilation is maintained even when the evaporator fan is off, while still preventing mold and mildew growth through intelligent humidity management
3Device complexity
If a PTAC unit introduces unconditioned outside air at ambient temperatures, then the system simplicity is maintained, but the air temperature and humidity levels remain uncontrolled
Solution Approach 1:
The patent merges the outside air conditioning function with the existing PTAC unit by integrating an evaporator coil and controls into the standard PTAC configuration. This combination allows the unit to condition outside air for temperature and humidity control while maintaining the compact, standardized form factor of conventional PTAC units
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 system effectively dehumidifies and conditions outside makeup air, preventing mold and mildew growth, ensuring improved indoor air quality by reducing outside air temperature and humidity, and meeting ASHRAE and local building code requirements.
Implementation Method 1
a second evaporator coil that is positioned to receive outside air for channeling therethrough from an outer side to an inner side
Implementation Method 2
A compressor is in fluid communication with and upstream of the second condenser coil and downstream of the second evaporator coil
Implementation Method 3
A second condenser coil is positioned to receive outside air for channeling therethrough from an inner side to an outer side and thence to the outside
Data Source
AI summary
An air conditioning unit is for cooling and dehumidifying outside air for flowing into an enclosed space from outside. The unit is interposable between a first evaporator coil and a first condenser coil and comprises a second evaporator coil that is positioned to receive outside air for channeling therethrough from an outer to an inner side and thence to the enclosed space. A second condenser coil is positioned to receive outside air for channeling therethrough from an inner to an outer side and thence to the outside. A compressor is in fluid communication with and upstream of the second condenser coil and downstream of the second evaporator coil. Another embodiment is intended as a unitary system and includes a unitary compressor and condenser coil, with one evaporator coil for processing inside air and another for channeling outside air into the enclosed space.