Methods and systems for mini-split liquid desiccant air conditioning
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Solution Overview
Problem
Conventional mini-split air conditioning systems are inefficient in managing high humidity in small buildings, as they primarily provide sensible cooling without effective dehumidification, leading to unacceptable humidity levels on days with low cooling demands.
Innovation Solution
A mini-split liquid desiccant air conditioning system where liquid desiccant flows down a support plate as a falling film, contained by a microporous membrane, absorbing both latent and sensible heat from the air stream, with a heat transfer fluid that is cooled or heated by a refrigerant compressor or external sources, and a regenerator that rejects heat to the environment, allowing for efficient cooling and dehumidification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional mini-split air conditioning systems are used, then sensible cooling is provided, but dehumidification is ineffective leading to high humidity levels
Solution Approach 1:
The invention changes the fundamental operating parameter from sensible cooling (temperature reduction only) to latent cooling (moisture removal through desiccant absorption). The liquid desiccant system absorbs moisture from air through hygroscopic properties, fundamentally changing how humidity is controlled compared to conventional evaporative cooling.
Solution Approach 2:
The liquid desiccant acts as an intermediary substance between the air stream and the cooling system. Instead of directly cooling air through refrigerant evaporation, the desiccant mediates the moisture removal process by absorbing water vapor, then the diluted desiccant is regenerated separately to concentrate and reuse.
2Productivity
If liquid desiccant systems are used, then efficient dehumidification is achieved, but system complexity increases due to membrane containment and regeneration requirements
Solution Approach 1:
The system is segmented into two independent functional units: a conditioner unit that handles dehumidification and a regenerator unit that handles desiccant concentration. This segmentation allows each unit to be optimized for its specific function and simplifies the overall system architecture by separating the moisture removal process from the desiccant regeneration process.
Solution Approach 2:
A heat exchanger serves as an intermediary device between the conditioner and regenerator, enabling thermal energy transfer for desiccant regeneration without requiring direct mechanical connection or complex control systems. The heat exchanger mediates the thermal coupling between the two units, simplifying control while maintaining efficiency.
3Ease of manufacture
If conventional mini-split systems are used, then installation requires high-pressure refrigerant lines, but this increases installation cost and complexity
Solution Approach 1:
The invention replaces the high-pressure mechanical refrigerant circulation system with a low-pressure liquid desiccant circulation system. Instead of using compressed refrigerant gases requiring specialized high-pressure lines and components, the system uses liquid desiccant that can be pumped through standard low-pressure piping, dramatically simplifying installation requirements.
Solution Approach 2:
The system transitions from pneumatic refrigerant circulation (gas-phase refrigerant under pressure) to hydraulic desiccant circulation (liquid-phase desiccant under low pressure). This hydraulic approach uses standard water-like piping systems rather than specialized refrigerant lines, making installation comparable to conventional water heating or cooling systems.
4Temperature
If evaporator coil is used for cooling, then sensible cooling is effective, but moisture removal capability is insufficient on low cooling demand days
Solution Approach 1:
The invention changes the primary cooling mechanism from sensible heat removal (evaporator coil) to latent heat removal (desiccant absorption). The liquid desiccant system is specifically designed to absorb moisture through phase change and hygroscopic absorption, providing superior moisture removal capability compared to evaporative cooling which primarily addresses temperature control.
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 provides efficient cooling and dehumidification at low capital and energy costs, reducing electricity consumption and eliminating the need for high-pressure refrigerant lines, while also enabling heating and humidification capabilities for winter conditions.
Implementation Method 1
liquid desiccant flows down the face of a support plate as a falling film... absorbing both latent and sensible heat from the air stream
Implementation Method 2
absorbing both latent and sensible heat from the air stream into the liquid desiccant
Implementation Method 3
the desiccant is contained by a microporous membrane
Data Source
AI summary
A split liquid desiccant air conditioning system is disclosed for treating an air stream flowing into a space in a building. The split liquid desiccant air-conditioning system is switchable between operating in a warm weather operation mode and a cold weather operation mode.