Systems and Methods for Generating Water From Air
Systems and methods for heat exchange and water generation are disclosed. Water generation systems described herein include a housing with a front surface comprising a solar thermal portion to convert solar radiation into heat and a solar electric portion to convert solar radiation into electrical energy. A sorption unit or layer captures water vapor from a process gas during a sorption mode and releases water vapor to a regeneration fluid heated by the solar thermal portion during a desorption mode. A heat exchange assembly includes a condenser to condense water from the regeneration fluid and a recuperator to transfer heat between fluid flow segments. Methods include directing a regeneration fluid along a flow path through a solar thermal portion, capturing and releasing water vapor via a sorption unit or layer, transferring heat using a recuperator, directing cooling fluid through a condenser, and condensing water vapor from the regeneration fluid.
1 . A water generation system comprising:
a housing having a front surface to collect solar radiation and a rear surface opposite the front surface, wherein the front surface comprises:
a solar thermal portion having a first area to convert solar radiation collected thereon to heat; and
a solar electric portion having a second area to convert solar radiation collected thereon to electrical energy;
a sorption layer disposed below the solar thermal portion and comprising a hygroscopic material to capture water vapor from a process gas during a sorption mode, and release water vapor to a regeneration fluid heated via the solar thermal portion during a desorption mode; and,
a heat exchange assembly disposed below the solar electric portion and comprising:
a condenser to condense water from the regeneration fluid;
a recuperator comprising a plurality of longitudinally extending heat exchange plates defining alternating flow layers to transfer heat from a first hot-side regeneration fluid flow output from the sorption layer to a second cold-side regeneration fluid flow output from the condenser.
2 . The system of claim 1 , wherein the housing further comprises a plurality of sidewalls extending downward from a periphery of the front surface to the rear surface to form a uniform planar configuration; and, wherein the sorption layer, the condenser and the recuperator are located within the housing.
3 . The system of claim 1 , wherein the solar thermal portion includes a transparent top cover layer and an interstitial layer to allow solar radiation to impinge upon the sorption layer positioned below the interstitial layer; and, wherein the solar electric portion comprises the transparent top cover layer and a photovoltaic panel positioned above the heat exchange assembly.
4 . The system of claim 1 , wherein the sorption layer is positioned adjacent to the heat exchange assembly within the housing.
5 . The system of claim 1 , wherein the first area of the solar thermal portion for solar thermal generation and the second area of the solar electric portion for solar electric generation are configured to maximize a water production rate.
6 . The system of claim 5 , wherein a total heat exchange surface area of the recuperator is 15-50% of the total heat exchange surface area for the heat exchange assembly.
7 . The system of claim 5 , wherein a total heat exchange surface area of the recuperator is 20-30% of the total heat exchange surface area for the heat exchange assembly.
8 . The system of claim 5 , wherein a front surface area of the system is less than or equal to 3 m 2 and, the first area of the solar thermal portion is 40-60% of the front surface area of the system.
9 . The system of claim 1 , wherein each of the plurality of longitudinally extending heat exchange plates have a thickness below 2 mm.
10 . The system of claim 1 , wherein the alternating flow layers have a spacing less than 12 mm.
11 . The system of claim 1 , wherein the first hot-side regeneration fluid flow is at least partially counter to the second cold-side regeneration fluid flow in an adjacent flow layer.
12 . The system of claim 1 , wherein the recuperator is a hybrid flow recuperator comprising a turn in a regeneration flow path, wherein the first hot-side regeneration fluid flows at least partially counter to the second cold-side regeneration fluid flow in a first section of a flow layer and the first hot-side regeneration fluid flow flows at least partially parallel to the second cold-side regeneration fluid flow in a second section of the flow layer.
13 . The system of claim 1 , wherein the condenser condenses water from the regeneration fluid via heat transfer from the regeneration fluid to a cooling fluid comprising ambient air.
14 . The system of claim 13 , wherein the condenser transfers heat from the regeneration fluid flowing in a closed-loop via heat transfer from the regeneration fluid to ambient air, and wherein ambient air is directed through a cooling flow path through the condenser in an open-loop via a fan.
15 . The system of claim 14 , wherein the fan is powered by the electrical energy generated by the solar electric portion of the system.
16 . The system of claim 1 , wherein the water generation system is configured to be installed with the solar thermal portion on a west side and the solar electric portion on an east side in a Northern hemisphere.
17 . The system of claim 1 , further comprising a controller to increase a relative humidity in the regeneration fluid output from the sorption layer to drive condensation of water vapor in the condenser, thereby producing liquid water during the desorption mode.
18 . The system of claim 17 , wherein the controller is configured to:
flow the process gas in a first direction along a series flow path across or through a first sorption unit of the sorption layer and then a second sorption unit of the sorption layer;
determine a water content of the first sorption unit, the second sorption unit, or a combination thereof;
flow the process gas in a second direction opposite from the first direction along a series flow path across or through the second sorption unit, and then the first sorption unit if the water content of the first sorption unit is greater than a predetermined threshold, the water content of the second sorption unit is less than a predetermined threshold, or a combination thereof.
19 . A method for generating water comprising:
directing a regeneration fluid in a regeneration flow path including:
a solar thermal portion to heat the regeneration fluid;
a sorption layer comprising a hygroscopic material to capture water vapor from a process gas during a sorption mode, and release water vapor to a regeneration fluid during a desorption mode;
a heat exchange assembly comprising a recuperator and a condenser;
transferring, via the recuperator comprising a plurality of longitudinally extending heat exchange plates defining alternating flow layers, heat from a first hot-side regeneration fluid flow output from the sorption layer to a second cold-side regeneration fluid flow output from the condenser;
directing a cooling fluid through at least one pass in a cooling flow path of the condenser;
transferring, via the condenser comprising a plurality of longitudinally extending heat exchange plates defining alternating flow layers, heat from the first hot-side regeneration fluid flow to a cooling fluid; and,
condensing, via the condenser, water vapor from the regeneration fluid.
20 . The method of claim 19 , further comprising generating electrical energy via a PV panel to power one or more fans to flow the regeneration fluid in the regeneration flow path, the process gas in a process flow path, the cooling fluid in a cooling flow path or a combination thereof.