Membrane Energy Recovery Air Conditioning Without Desiccant Carryover
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Solution Overview
Problem
Conventional energy exchange systems for conditioning air in enclosed structures are inefficient, particularly in environments with extreme outside conditions, as they require significant auxiliary energy and can overcool or overheat the air, and direct contact liquid desiccant systems risk damaging HVAC equipment due to aerosolized desiccant transport.
Innovation Solution
An energy exchange system incorporating a supply air flow path, an exhaust air flow path, and energy recovery devices, including a liquid-to-air membrane energy exchanger (LAMEE) downstream from an energy recovery device, with a regenerator and liquid handling device that circulates desiccant through a moisture transfer loop to efficiently condition air by pre-conditioning with energy recovery and further conditioning with LAMEE, while preventing desiccant transport into the air stream.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional energy exchange systems are used to condition air in extreme environments, then air conditioning is achieved, but significant auxiliary energy is required
Solution Approach 1:
The energy recovery device pre-conditions the supply air by recovering energy from exhaust air before the air enters the LAMEE, reducing the workload and auxiliary energy required for final conditioning
Solution Approach 2:
A liquid desiccant circulates through the system as an intermediary medium, transferring moisture between air streams through membrane contact without direct mixing, enabling efficient latent heat recovery with minimal auxiliary energy
2Quantity of substance
If vapor compression systems are used to dehumidify hot and humid air, then dehumidification is achieved, but the air is overcooled and requires reheating
Solution Approach 1:
The liquid desiccant system changes the approach parameter from temperature-based condensation to concentration-based absorption, allowing dehumidification without overcooling the air below its dew point
Solution Approach 2:
The system utilizes phase transition of water between liquid and vapor phases through evaporation and condensation processes in the LAMEE, enabling moisture transfer without excessive temperature changes
3Temperature
If direct contact liquid desiccant systems are used, then air conditioning is achieved, but aerosolized desiccant may damage HVAC equipment
Solution Approach 1:
A hydrophobic membrane acts as an intermediary barrier between the liquid desiccant and air stream, allowing moisture transfer through the membrane while preventing aerosolization and direct contact between desiccant and air
Solution Approach 2:
The hydrophobic membrane functions as a thin film barrier that permits vapor transmission while blocking liquid passage, eliminating desiccant aerosol generation while maintaining effective moisture transfer
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 system reduces energy consumption by pre-conditioning air with energy recovery, minimizing the workload of the LAMEE, and prevents desiccant aerosolization, ensuring efficient and safe air conditioning without overheating or overcooling, achieving higher efficiency and reliability compared to conventional systems.
Implementation Method 1
energy in the form of heat and water vapor is transferred between the LAMEEs in the supply and exhaust ducts
Implementation Method 2
liquid-to-air membrane energy exchanger (LAMEE)
Implementation Method 3
energy recovery devices... positioned in both the supply air flow path and the exhaust air flow path
Implementation Method 4
transfer of sensible (heat) and latent (moisture) energy between the exhaust air and the supply air
Implementation Method 5
liquid handling device that circulates desiccant through a moisture transfer loop
Implementation Method 6
regenerator configured to be operated during off-hours to regenerate a desiccant
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
Certain Embodiments provide an energy exchange system that includes a supply air flow path, an exhaust air flow path, an energy recovery device disposed within the supply and exhaust air flow paths, and a supply conditioning unit disposed within the supply air flow path. The supply conditioning unit may be downstream from the energy recovery device. Certain embodiments provide a method of conditioning air including introducing outside air as supply air into a supply air flow path, pre-conditioning the supply air with an energy recovery device, and fully-conditioning the supply air with a supply conditioning unit that is downstream from the energy recovery device.