# US 11,898,333 B2 · Heat and mass exchanger made with alginate-bentonite biocomposite hydrogel for water vapor capture, and production process thereof

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- Number: US 11,898,333 B2
- Document ID: US11898333B2
- Status: Granted
- Kind: B2
- Application number: 18/005,188
- Filed: 2021-07-13
- Published: 2023-10-05
- Granted: 2024-02-13
- Earliest claimed: 2020-07-13
- Assignees: Politecnico Di Torino; Princeton University
- Applicants: Politecnico Di Torino; Princeton University
- Inventors: Vincenzo Maria Gentile; Marco Simonetti; Francesco Neirotti; Michael Bozlar; Forrest Meggers
- Web page: https://patentgrep.com/patent/US11898333B2

## CPC

- B01D 53/02: by adsorption, e.g. preparative gas chromatography {(solid sorbent compositions B01J20/00, preparation of inorganic compounds or elements C01)}
- E03B 3/28: from humid air (condensing of vapours in general B01D5/00; dehumidification of air for air-conditioning F24F3/14)
- B01D 53/261: {by adsorption}
- B01D 53/265: {by refrigeration (condensation)}
- B01D 53/28: Selection of materials for use as drying agents
- B01J 20/12: Naturally occurring clays or bleaching earth
- B01J 20/24: Naturally occurring macromolecular compounds, e.g. humic acids or their derivatives
- B01J 20/28045: {Honeycomb or cellular structures; Solid foams or sponges}
- B01J 20/3007: {Moulding, shaping or extruding}
- B01J 20/3085: {Chemical treatments not covered by groups B01J20/3007 - B01J20/3078}
- B01D 2253/106: Silica or silicates
- B01D 2253/202: Polymeric adsorbents
- B01D 2253/25: Coated, impregnated or composite adsorbents
- B01D 2253/3425: Honeycomb shape
- B01D 2257/80: Water
- B01D 2258/06: Polluted air
- B01J 2220/46: Materials comprising a mixture of inorganic and organic materials (materials coated or impregnated on a carrier B01J20/32)
- Y02A 20/00: Water conservation; Efficient water supply; Efficient water use
- 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)
- E03B: INSTALLATIONS OR METHODS FOR OBTAINING, COLLECTING, OR DISTRIBUTING WATER (drilling wells, obtaining fluids in general from wells E21B; pipe-line systems in general F17D)
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- Y02A: TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE

## Abstract

A high performance ADSorption Heat eXchanger ADS-HX includes a hygroscopic composite biopolymer, a heat exchange medium in contact with the hygroscopic composite biopolymer and a hollow conduit in contact with the heat exchange medium, into which hollow conduit either a cooling fluid or a heating fluid are alternately made to pass, so that the adsorption heat exchanger can be operated under high ambient temperatures and low relative humidity conditions, which are typical of arid climates. A process is provided for producing the aforesaid high performance ADSorption Heat eXchanger ADS-HX. A preferred and advantageous application of the aforesaid high performance ADSorption Heat eXchanger ADS-HX is in combination with the atmospheric water harvesting device described in the international application published at no. WO 2019/082000 A1 of the same Applicant.

## Claims

### Claim 1

An adsorption heat exchanger comprising
a hygroscopic composite biopolymer,
a heat exchange medium in contact with the hygroscopic composite biopolymer, and
a hollow conduit in contact with the heat exchange medium, into which hollow conduit either a cooling fluid or a heating fluid are alternately made to pass
wherein
the hygroscopic composite biopolymer comprises sodium alginate and calcium bentonite in a predetermined ratio,
and in that
the heat exchange medium has a honeycomb geometry,
so that the adsorption heat exchanger can be operated under high ambient temperatures and low relative humidity conditions, which are typical of arid climates.

### Claim 2 (depends on 1)

The adsorption heat exchanger according to claim 1, wherein the predetermined ratio between the sodium alginate and the calcium bentonite ranges from 1:1 to 1:10.

### Claim 3 (depends on 2)

The adsorption heat exchanger according to claim 2, wherein the predetermined ratio between the sodium alginate and the calcium bentonite is 1:1-1:2.

### Claim 4 (depends on 1)

The adsorption heat exchanger according to claim 1, wherein the sodium alginate has a concentration ranging between 0.5 and 4% of an entire mass of a hydrogel as in a supersaturated state.

### Claim 5 (depends on 1)

The adsorption heat exchanger according to claim 1, wherein the honeycomb geometry has a cell size raging in 3-5 mm, with an intercell perpendicular distance not greater than a half of the cell size; this geometry is inserted between two elements for a heat transfer, constituting a repeated base of the adsorption heat exchanger.

### Claim 6 (depends on 1)

An atmospheric water harvesting device comprising at least one adsorption heat exchanger according to claim 1, so that the atmospheric water harvesting device can provide a freshwater in regions around the world where physical and/or economical water scarcity force people to find alternative solutions for water access.

### Claim 7

A process for producing an adsorption heat exchanger comprising the following steps:
preparing a hygroscopic composite biopolymer by realizing a viscous gel containing main components of the hygroscopic polymer, i.e. sodium alginate and calcium bentonite in a predetermined ratio (step 100);
preparing a heat exchange medium having a honeycomb geometry and placing it in contact with the hygroscopic composite biopolymer (step 101),
preparing a hollow conduit and placing it in contact with the heat exchange medium (step 102), and
alternately making to pass into the hollow conduit either a cooling fluid or a heating fluid (step 103).

### Claim 8 (depends on 7)

The process according to claim 7, wherein the viscous gel is prepared by mixing a powder of the sodium alginate (2% by weight) and the calcium bentonite (4-10% by weight) with deionized water, until a complete mixing and a homogeneous fluid is obtained.

### Claim 9 (depends on 8)

The process according to claim 8, wherein the viscous gel is degassed, under a vacuum at a relative pressure between 200-500 mbar for at least 20 minutes.

### Claim 10 (depends on 9)

The process according to claim 9, wherein the viscous and degassed gel is injected in a prefabricated mold with a honeycomb geometry and the mold is deeply immersed in the deionized water/CaCl2 solution for at least 12 hours until a complete jellification.