Air conditioning system using thermally responsive liquid desiccants
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Solution Overview
Problem
Current air conditioning systems, particularly vapor compression and solid desiccant systems, are inefficient and environmentally impactful due to high energy consumption and the use of high Global Warming Potential refrigerants, as well as limitations in pumping liquids through systems for efficient heat and mass exchange.
Innovation Solution
An air conditioning system utilizing a lower critical solution temperature (LCST) liquid desiccant that separates into weak and strong phases upon heating, allowing for phase separation-based regeneration and evaporative cooling, eliminating the need for compressors and leveraging solar, waste, or electric heat for energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If vapor compression systems are used for air conditioning, then cooling capacity is achieved, but energy consumption increases and environmental harm occurs due to high GWP refrigerants
Solution Approach 1:
The patent replaces the mechanical vapor compression system with a thermally-driven liquid desiccant system. Instead of using compressors and high-GWP refrigerants, the system uses liquid desiccants that absorb moisture from air through hygroscopic properties, and regenerative heat exchangers that utilize thermal energy for dehumidification and cooling, thereby eliminating the need for mechanical compression and harmful refrigerants
Solution Approach 2:
The patent changes the fundamental operating parameters from mechanical pressure-based cooling to temperature and humidity-based thermal processing. By using liquid desiccants with varying concentrations and regenerative heat exchangers operating at different temperature levels, the system achieves cooling through thermodynamic parameter changes rather than mechanical compression
2Loss of substance
If solid desiccants are used for dehumidification, then moisture removal is achieved, but pumping capability is lost
Solution Approach 1:
The patent transitions from solid desiccants to liquid desiccants, enabling the use of hydraulic principles for pumping and circulating the desiccant solution through the system. The liquid form allows standard pumps to move the desiccant through heat exchangers and processing units, combining effective moisture removal with ease of operation and system integration
3Loss of substance
If hot air is used for desiccant regeneration, then moisture is removed from desiccant, but the hot moisture is exhausted unused
Solution Approach 1:
The patent merges the regeneration process with the cooling process by using regenerative heat exchangers that transfer thermal energy from the hot regenerated desiccant stream to the incoming desiccant stream. This combines moisture removal with preheating and precooling functions, eliminating energy waste by utilizing the thermal energy that would otherwise be discarded
Solution Approach 2:
The patent implements continuous regenerative heat exchange where the hot outgoing desiccant stream continuously preheats the incoming desiccant stream, and the cold outgoing stream precools incoming air or desiccant. This continuous heat recovery maintains useful thermal action throughout the cycle, eliminating interruptions and energy waste
4Temperature
If conventional heat exchangers are used, then heat transfer occurs, but efficiency is reduced compared to counterflow design
Solution Approach 1:
The patent employs counterflow heat exchanger design where the hot and cold streams flow in opposite directions, maintaining a more uniform temperature difference throughout the exchanger length. This dynamic flow arrangement maximizes the driving force for heat transfer at all points, significantly improving heat exchange efficiency compared to parallel or crossflow configurations
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 energy-efficient and environmentally friendly dehumidification and cooling without high GWP refrigerants, using only fans and pumps, and enables the use of phase-separated desiccants for efficient heat transfer and humidity control in buildings.
Implementation Method 1
The lower critical solution temperature (LCST) liquid desiccant can be configured to have a moderate phase liquid configured to separate into a weak phase liquid and strong phase liquid upon heating
Implementation Method 2
The absorber can be configured to receive the strong phase liquid. The strong phase liquid absorbs moisture from air thereby dehumidifying the air
Implementation Method 3
The desorber can be configured to receive the weak phase liquid wherein the weak phase liquid desorbs moisture to air thereby cooling the desorber through evaporative cooling
Implementation Method 4
The heater can be configured to transfer heat to the moderate phase liquid to separate the moderate phase liquid into the weak phase liquid and the strong phase liquid
Implementation Method 5
the air conditioning system can further include a recuperator configured to transfer heat to the moderate phase liquid from the weak phase liquid and the strong phase liquid
Implementation Method 6
the air conditioning system can further include an air-to-air heat exchanger configured to receive the dehumidified air from the absorber and the humidified air from the desorber and transfer heat from the dehumidified air to the humidified air
Data Source
AI summary
An exemplary embodiment of the present disclosure provides an air conditioning system including a lower critical solution temperature (LCST) liquid desiccant, a heater, a separator, an absorber, and a desorber. The lower critical solution temperature (LCST) liquid desiccant can be configured to have a moderate phase liquid configured to separate into a weak phase liquid and strong phase liquid upon heating. The heater can be configured to transfer heat to the moderate phase liquid to separate the moderate phase liquid into the weak phase liquid and the strong phase liquid. The separator can be configured to physically separate the weak phase liquid and strong phase liquid. The absorber can be configured to receive the strong phase liquid which absorbs moisture from air thereby dehumidifying the air. The desorber can be configured to receive the weak phase liquid which desorbs moisture to air thereby cooling the desorber through evaporative cooling.