Desiccant Air Conditioning With Porous Plates to Limit Carry-Over
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Solution Overview
Problem
Current air conditioning systems face inefficiencies in energy usage, particularly in dehumidification, due to the need for overcooling and the use of costly and complex low-pressure vacuum systems, and liquid desiccant systems suffer from desiccant carry-over and corrosion issues, as well as limitations in integrating with waste heat sources.
Innovation Solution
Integration of Solar Photo-Voltaic-Thermal (PVT) modules with desiccant air conditioning systems to provide both heat and electricity, using wavy plate structures with micro-porous membranes to manage desiccant flow and reduce corrosion, and employing thermally conductive plastics for efficient heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If liquid desiccant is sprayed on filter media to increase surface area, then dehumidification efficiency is improved, but desiccant carry-over into air stream increases causing corrosion
Solution Approach 1:
The patent uses porous filter media to hold and expose liquid desiccant to air stream. The porous structure provides large surface area for dehumidification while the media itself acts as a barrier preventing desiccant carry-over into the air stream, thus resolving the contradiction between dehumidification efficiency and corrosion prevention
Solution Approach 2:
The patent employs composite material structures combining filter media with liquid desiccant. The filter media serves dual functions: supporting the desiccant for efficient mass transfer and acting as a physical barrier to prevent corrosion-causing carry-over, thereby achieving both high productivity and harm reduction
2Area of stationary object
If filter media is used to support liquid desiccant, then surface area is increased, but fan power requirement increases due to air flow obstruction
Solution Approach 1:
The porous filter media provides large surface area for desiccant exposure while maintaining high air permeability. The interconnected pore structure allows air to flow through with minimal resistance, achieving both large effective area and low pressure drop, thus reducing fan power requirements
Solution Approach 2:
The filter media is designed with optimized local properties - high porosity and appropriate pore size distribution - to balance surface area provision with air flow resistance minimization, resolving the contradiction between increased area and energy consumption
3Area of stationary object
If filter media is used for dehumidification, then desiccant exposure area is increased, but thermal non-conductivity makes process adiabatic causing air heating
Solution Approach 1:
The porous filter media is designed with high thermal conductivity properties to enable effective heat transfer between the desiccant and air stream. This allows the dehumidification process to be non-adiabatic, preventing undesirable air heating while maintaining large desiccant exposure area
Solution Approach 2:
The composite structure of filter media and liquid desiccant is engineered with thermal conductivity considerations, using materials and configurations that facilitate heat transfer, thus resolving the contradiction between area increase and temperature control
4Reliability
If low pressure vacuum system is used in absorption chiller, then desiccant containment is achieved, but equipment cost and complexity significantly increase
Solution Approach 1:
The patent replaces the mechanical vacuum system with a passive liquid desiccant system operating at atmospheric pressure. The liquid desiccant naturally absorbs moisture from air without requiring vacuum equipment, eliminating complexity while maintaining effective dehumidification and containment
Solution Approach 2:
The liquid desiccant system is self-contained and operates without external vacuum equipment. The desiccant solution naturally performs the dehumidification function through its chemical properties, achieving reliable containment and operation without complex mechanical systems
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 enhances thermal performance, reduces fan and pump power, minimizes desiccant carry-over, and allows for more efficient use of waste heat, improving energy efficiency and system scalability while addressing corrosion concerns.
Implementation Method 1
using wavy plate structures with micro-porous membranes to manage desiccant flow and reduce corrosion
Implementation Method 2
employing thermally conductive plastics for efficient heat transfer
Implementation Method 3
liquid desiccant systems such as the systems manufactured by DuCool and Agam use a strong desiccant material such as a CaCl2 and water or LiCl2 and water solution to absorb water vapor in the air
Data Source
AI summary
A desiccant air conditioning system for cooling an air stream entering a building space includes a conditioner and a regenerator. The conditioner includes structures arranged in a substantially vertical orientation that are spaced apart from each other with an air stream gap between each pair of adjacent structures. Each structure has a surface facing an air stream gap across which a liquid desiccant can flow. The air stream flows through the air stream gaps between the structures such that the liquid desiccant dehumidifies the air stream. Each structure further includes a separate desiccant collector at a lower end of the surface for collecting liquid desiccant that has flowed across the surface of the structure. The desiccant collectors are spaced apart from each other to permit airflow therebetween. A photovoltaic-thermal module heats a heat transfer fluid used to heat the liquid desiccant in the regenerator.