Multi-Stage Membrane Dehumidification for Low-Energy Air Cooling
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Solution Overview
Problem
Traditional HVAC systems require cooling air to 55° F. for dehumidification, which is inefficient and has a low coefficient of performance (COP) of approximately 3-5, as they rely on refrigerant compressors for both sensible and latent cooling, leading to high energy consumption and limited dehumidification effectiveness.
Innovation Solution
The implementation of a dehumidification system using water vapor permeable membranes to establish a humidity gradient, allowing water vapor to be removed from air without initial condensation, by creating a pressure differential across the membranes, thereby reducing the humidity of the air while blocking other air components, and using a vacuum pump to condense the vapor efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional refrigerant compressors are used for dehumidification by cooling air to 55° F., then water vapor is condensed and removed from air, but energy consumption is high and coefficient of performance is low (COP of 3-5)
Solution Approach 1:
The patent extracts only the water vapor component from the air stream using selective membranes, rather than cooling the entire air mass to condensation temperature. The membrane selectively permeates water vapor while blocking other air components, allowing dehumidification to occur without the energy-intensive cooling process required by traditional systems.
Solution Approach 2:
The patent replaces the mechanical refrigeration system (compressor, condenser, evaporator) with a membrane-based separation system. Instead of using phase change and heat transfer mechanisms requiring large mechanical components, the system uses selective permeation through membranes to achieve dehumidification, significantly reducing mechanical complexity and energy consumption.
2Reliability
If air is cooled to 55° F. to achieve dehumidification, then humidity ratio is reduced to 0.009 pounds of H2O per pound of dry air, but the air temperature must be lowered significantly which reduces system efficiency
Solution Approach 1:
The patent applies local quality by creating different conditions for different components of the air stream. The membrane provides a selective interface where water vapor experiences different permeation properties than other air components. This allows water vapor to be removed while the bulk air maintains its original temperature, avoiding the need to cool the entire air mass.
Solution Approach 2:
The patent changes the operational parameter from temperature-based condensation to permeation-based separation. Instead of controlling dehumidification through temperature reduction to the dew point, the system controls water vapor removal through membrane permeation characteristics, allowing dehumidification to occur at ambient or elevated temperatures.
3Adaptability or versatility
If refrigerant compressors are used for both sensible and latent cooling, then both temperature reduction and humidity removal are achieved, but the system complexity and energy consumption increase
Solution Approach 1:
The patent segments the dehumidification function from the cooling function. The membrane-based system handles latent heat removal (water vapor condensation) independently, while sensible cooling can be addressed separately if needed. This segmentation allows each subsystem to be optimized independently, reducing overall system complexity compared to integrated refrigeration systems that must handle both functions simultaneously.
Solution Approach 2:
The membrane system provides multi-functionality by simultaneously achieving dehumidification and potential heat recovery. The same membrane structure that separates water vapor can also facilitate heat transfer, allowing the system to perform multiple functions with a single component, thereby reducing overall system complexity.
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 significantly reduces energy consumption, achieves a higher COP of up to five times that of conventional systems, and allows for efficient dehumidification without lowering the air temperature, resulting in a more efficient and cost-effective HVAC system.
Implementation Method 1
a first dehumidification unit (12) that receives the inlet air (14A) and removes water vapor (26) from the inlet air (14A) to form outlet air (14B)
Implementation Method 2
by creating a pressure differential across the membranes
Implementation Method 3
a vacuum pump (52) that compresses the water vapor (26A) to a partial pressure just high enough to facilitate condensation of the water vapor (26A)
Implementation Method 4
a condensation unit (54) that condenses the water vapor (26B) into liquid water
Data Source
AI summary
The present disclosure relates to systems and methods for dehumidifying air by establishing a humidity gradient across a water selective permeable membrane in a dehumidification unit. Water vapor from relatively humid atmospheric air entering the dehumidification unit is extracted by the dehumidification unit without substantial condensation into a low pressure water vapor chamber operating at a partial pressure of water vapor lower than the partial pressure of water vapor in the relatively humid atmospheric air. For example, water vapor is extracted through a water permeable membrane of the dehumidification unit into the low pressure water vapor chamber. As such, the air exiting the dehumidification unit is less humid than the air entering the dehumidification unit. The low pressure water vapor extracted from the air is subsequently condensed and removed from the system at ambient conditions.