# US 11,998,871 B2 · Electrodialytic liquid desiccant dehumidifying system

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- Number: US 11,998,871 B2
- Document ID: US11998871B2
- Status: Granted
- Kind: B2
- Application number: 17/400,774
- Filed: 2021-08-12
- Published: 2021-12-02
- Granted: 2024-06-04
- Earliest claimed: 2018-11-26
- Assignees: Mojave Energy Systems, Inc.
- Applicants: Mojave Energy Systems, Inc.
- Inventors: Michael Benedict; Eugene S. Beh; Elif Karatay
- Web page: https://patentgrep.com/patent/US11998871B2

## CPC

- B01D 53/1425: {Regeneration of liquid absorbents}
- B01D 53/1412: {Controlling the absorption process}
- B01D 53/18: Absorbing units; Liquid distributors therefor (B01D3/16, B01D3/26, B01D3/30 take precedence; packing elements B01J19/30, B01J19/32)
- B01D 53/263: {by absorption}
- B01D 61/002: {Forward osmosis or direct osmosis}
- B01D 61/422: {Electrodialysis}
- B01D 61/58: Multistep processes
- F24F 3/1417: {with liquid hygroscopic desiccants}
- H01M 8/188: {by recharging of redox couples containing fluids; Redox flow type batteries}
- H01M 8/227: {Dialytic cells or batteries; Reverse electrodialysis cells or batteries}
- B01D 53/268: {by diffusion}
- B01D 2258/06: Polluted air
- B01D 2311/2512: to feed side
- F24F 3/1411: {by absorbing or adsorbing water, e.g. using an hygroscopic desiccant}
- F24F 2003/144: {by dehumidification only}
- F24F 2003/1458: {using regenerators}
- Y02E 60/50: Fuel cells
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- F24F: AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING (removing dirt or fumes from areas where they are produced B08B15/00; vertical ducts for carrying away waste gases from buildings E04F17/02; tops for chimneys or ventilating shafts, terminals for flues F23L17/02)
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

Air flows across an air-liquid interface such that liquid desiccant flowing through the interface absorbs water from the air and is thereby diluted to form an output stream. The output stream is circulated through an electrodialytic stack having a central ionic exchange membrane and first and second outer ionic exchange membranes. A redox shuttle loop circulates around the first and second outer ionic exchange membranes. A voltage is applied across the electrodialytic stack, which regenerates the liquid desiccant.

## Claims

### Claim 1

An air conditioning system, comprising:
an electrodialytic stack comprising:
a pump-driven, liquid desiccant loop with a diluted stream and a concentrated stream of liquid desiccant separated by a central ionic exchange membrane;
a redox shuttle loop flowing across first and second outer ionic exchange membranes of a different type than the central ionic exchange membrane, the redox shuttle loop separated from the diluted stream and the concentrated stream of the liquid desiccant loop by the first and second outer ionic exchange membranes; and
electrodes that are operable to apply a voltage across the electrodialytic stack;
an air-liquid interface in fluid communication with the concentrated stream, the concentrated stream being diluted via absorption of water from the air via the air-liquid interface to form an output stream of the liquid desiccant and a stream of dehumidified air, the output stream from the air-liquid interface being split into the diluted stream and the concentrated stream upon entry into the electrodialytic stack; and
a sensible cooling element that receives and cools the dehumidified air.

### Claim 2 (depends on 1)

The air conditioning system of claim 1, wherein the voltage causes:
a first ionic movement across the central ionic exchange membrane and the first outer ionic exchange membrane resulting in a desiccant concentrate moving from the diluted stream to a first redox stream of the redox shuttle loop and to the concentrated stream; and
a second ionic movement across the second outer exchange membrane that causes movement of the desiccant concentrate from a second redox stream of the redox shuttle loop to the concentrated stream.

### Claim 3 (depends on 1)

The air conditioning system of claim 1, wherein the central ionic exchange membrane comprises a cation exchange membrane and wherein the first and second outer ionic exchange membranes comprise anion exchange membranes.

### Claim 4 (depends on 2)

The air conditioning system of claim 2, wherein the desiccant concentrate comprises NaCl, LiCl, LiBr, CaCl2), or combinations thereof.

### Claim 5 (depends on 2)

The air conditioning system of claim 2, wherein the redox shuttle loop comprises [BTMAP-Fc]2+/[BTMAP-Fc]3+.

### Claim 6 (depends on 1)

The air conditioning system of claim 1, wherein the central ionic exchange membrane comprises an anion exchange membrane and wherein the first and second outer ionic exchange membranes comprise cation exchange membranes.

### Claim 7 (depends on 6)

The air conditioning system of claim 6, wherein a desiccant concentrate of the liquid desiccant loop comprises LiCl and wherein the redox shuttle loop comprises ferrocyanide/ferricyanide [Fe(CN)6]4−/3− or a negatively charged ferrocene derivative.

### Claim 8 (depends on 1)

The air conditioning system of claim 1, further comprising heat transfer elements in thermal communications with the air-liquid interface, the heat transfer elements carrying heat generated from the absorption of the water from the air into the output stream at the air-liquid interface to a heat sink.

### Claim 9 (depends on 1)

The air conditioning system of claim 1, further comprising a reservoir that stores a portion of at least one of the diluted stream and the concentrated stream of the liquid desiccant, the stored portion being added to the liquid desiccant loop if the water absorbed from the air does not equal an amount of water added to the diluted stream.

### Claim 10 (depends on 1)

The air conditioning system of claim 1, further comprising an electrodialytic battery in fluid communication with a reservoir storing a portion of fluid from the redox shuttle loop, the stored portion being used to generate electricity via the electrodialytic battery.

### Claim 11 (depends on 2)

The air conditioning system of claim 2 further comprising:
a second redox shuttle loop with third and fourth redox streams separated from a second diluted stream and a second concentrated stream of the liquid desiccant loop by respective third and fourth outer ionic exchange membranes; and
a second central ionic exchange membrane between the third and fourth outer ionic exchange membranes, the voltage causing the second ionic movement across the second central ionic exchange membrane and a third ionic movement across the third outer ionic exchange membrane that causes desiccant concentrates from the second diluted stream to be moved to the third redox stream and to the second concentrated stream.

### Claim 12 (depends on 11)

The air conditioning system of claim 11, wherein the diluted stream of the liquid desiccant loop is split into the second dilute stream and the second concentrated stream as it exits from membrane contact with the redox shuttle loop such that the second diluted stream flows between the second central ionic exchange membrane and the third outer ionic exchange membrane and the second concentrated stream flows between the second central ionic exchange membrane and the fourth outer ionic exchange membrane.

### Claim 13 (depends on 12)

The air conditioning system of claim 12, wherein the second concentrated stream has approximately an equivalent desiccant concentrate level as the output stream and is remixed with the output stream.

### Claim 14

A liquid desiccant system, comprising:
an electrodialytic stack comprising:
a liquid desiccant loop with a diluted stream and a concentrated stream of liquid desiccant separated by a central ionic exchange membrane;
a redox shuttle loop comprising a positively charged ferrocene derivative and with first and second redox streams separated from the diluted stream and the concentrated stream of the liquid desiccant loop by respective first and second outer ionic exchange membranes of a different type than the central ionic exchange membrane; and
first and second electrodes that are operable to apply a voltage across the electrodialytic stack; and
an air-liquid interface in fluid communication with the concentrated stream of the liquid desiccant, the air-liquid interface exposing the concentrated stream of the liquid desiccant to air flowing across the air-liquid interface, the concentrated stream being diluted via absorption of water from the air to form an output stream, the output stream being circulated back into the liquid desiccant loop of the electrodialytic stack.

### Claim 15 (depends on 14)

The liquid desiccant system of claim 14, wherein the liquid desiccant comprises NaCl, LiCl, LiBr, CaCl2), or combinations thereof.

### Claim 16 (depends on 14)

The liquid desiccant system of claim 14, further comprising heat transfer elements in thermal communication with the air-liquid interface to remove heat from the liquid desiccant.

### Claim 17 (depends on 14)

The liquid desiccant system of claim 14, further comprising a heat exchanger coupled to the air-liquid interface to remove heat generated by absorption of water in the liquid desiccant.