Atmospheric water harvesters
View Patent ↗An atmospheric water harvester includes a cooling member over which humid air flows to condense moisture from the atmosphere. The cooling member may be the evaporator of a conventional, gas vapor-based refrigeration circuit. If a gas vapor-based refrigeration circuit is used, the compressor of the circuit may be variable speed. A fan or impeller used to move air through the system may also be variable speed. A preferred embodiment includes a variable flow geometry thermal economizer section configured such that, to varying degrees, the incoming air may be pre-cooled, before it passes over the cooling member, by heat exchange with colder air that has already flowed over the cooling member.
1. An atmospheric water harvester (AWH), comprising:
a housing;
a cooling device disposed within the housing for condensing atmospheric moisture;
an airflow passageway extending through the housing from a first inlet, across the cooling device, to one or more outlets;
a heat exchanger having a first heat exchange portion disposed upstream of the cooling device and a second heat exchange portion disposed downstream of the cooling device, the heat exchanger being arranged to transfer heat from air traversing the first heat exchange portion to cooler air that has traversed the cooling device and that is traversing the second heat exchange portion, whereby air entering the airflow passageway through the first inlet can be pre-cooled before traversing the cooling device;
a second inlet, which is a bypass inlet, arranged to introduce air into the airflow passageway at a location downstream of the heat exchanger's first heat exchange portion and upstream of the cooling device, whereby air entering the airflow passageway through the second inlet is not pre-cooled before traversing the cooling device;
one or more fans or impellers arranged to propel air through the atmospheric water harvester; and
ambient temperature and humidity sensors;
wherein the atmospheric water harvester further comprises a controller that is programmed to control the relative amounts of air entering the airflow passageway through the first and second inlets based on measured ambient temperature and humidity so as to achieve a predetermined level of relative humidity of air that reaches to traverse the cooling device.
2. The AWH of claim 1 , wherein the heat exchanger comprises an air-to-air heat exchanger; the first heat exchange portion comprises a first set of heat transfer flow passageways; and
the second heat exchange portion comprises a second set of heat transfer flow passageways in thermal communication with the first set of heat transfer flow passageways.
3. The AWH of claim 1 , wherein the relative sizes of the first and second inlets are variable so as to control the relative amounts of air entering the airflow passageway through the first and second inlets.
4. The AWH of claim 3 , wherein the sizes of the first and second inlets directly and inversely co-vary, with the size of the first inlet being at a maximum when the size of the second inlet is at a minimum and vice-versa.
5. The AWH of claim 4 , further comprising a sliding panel the position of which defines the relative sizes of the first and second inlets.
6. The AWH of claim 4 , wherein the minimum size of each of the first and second inlets is totally closed.
7. The AWH of claim 3 , wherein the sizes of the first and second inlets are independently variable.
8. The AWH of claim 1 , wherein said one or more fans or impellers comprises a variable speed fan or impeller associated with each of the first and second inlets whereby the relative amounts of air entering the airflow passageway through the first and second inlets can be controlled by varying the speeds of the respectively associated fans or impellers.
9. The AWH of claim 1 , wherein said one or more fans or impellers comprises a variable speed fan or impeller located at a downstream portion of said airflow passageway.
10. The AWH of claim 1 , wherein the cooling device is metal and has a coating which prevents metal from dissolving into water condensing thereon.
11. The AWH of claim 1 , wherein the cooling device has an antimicrobial coating thereon.
12. The AWH of claim 1 , wherein the AWH comprises a vapor compression-based refrigeration system including a condenser, an evaporator, and a compressor and said cooling device comprises said evaporator.
13. The AWH of claim 12 , wherein the compressor is a variable speed compressor.
14. The AWH of claim 1 , further comprising a water collection region disposed below said cooling device for collecting water that has condensed on said cooling device and run off of said cooling device under the influence of gravity.
15. The AWH of claim 14 , further comprising a pump disposed within said water collection region for transferring water from said water collection region to a user.
16. The AWH of claim 15 , further comprising a water filter through which water transferred by said pump passes.
17. The AWH of claim 1 , further comprising an air filter associated with each of said first and second inlets.
18. An atmospheric water harvester (AWH), comprising:
a housing;
a cooling device disposed within the housing for condensing atmospheric moisture;
an airflow passageway extending through the housing from a first, variable-flow-volume inlet, across the cooling device, to one or more outlets;
a heat exchanger having a first heat exchange portion disposed upstream of the cooling device and a second heat exchange portion disposed downstream of the cooling device, the heat exchanger being arranged to transfer heat from air traversing the first heat exchange portion to cooler air that has traversed the cooling device and that is traversing the second heat exchange portion, whereby air entering the airflow passageway through the first inlet can be pre-cooled before traversing the cooling device;
a second variable-flow-volume inlet, which is a bypass inlet, arranged to introduce air into the airflow passageway at a location downstream of the heat exchanger's first heat exchange portion and upstream of the cooling device, whereby air entering the airflow passageway through the second inlet is not pre-cooled before traversing the cooling device;
ambient temperature and humidity sensors; and
one or more fans or impellers arranged to propel air through the atmospheric water harvester;
wherein the atmospheric water harvester further comprises a controller that is programmed to control the relative amounts of air entering the airflow passageway through the first and second variable-flow-volume inlets based on measured ambient temperature and humidity so as to achieve a predetermined level of relative humidity of air that reaches to traverse the cooling device.
19. An atmospheric water harvester (AWH), comprising:
a housing;
a cooling device disposed within the housing for condensing atmospheric moisture;
an airflow passageway extending through the housing from a first inlet, across the cooling device, to one or more outlets;
a heat exchanger having a first heat exchange portion disposed upstream of the cooling device and a second heat exchange portion disposed downstream of the cooling device, the heat exchanger being arranged to transfer heat from air traversing the first heat exchange portion to cooler air that has traversed the cooling device and that is traversing the second heat exchange portion, whereby air entering the airflow passageway through the first inlet can be pre-cooled before traversing the cooling device;
a second inlet, which is a bypass inlet, arranged to introduce air into the airflow passageway at a location downstream of the heat exchanger's first heat exchange portion and upstream of the cooling device, whereby air entering the airflow passageway through the second inlet is not pre-cooled before traversing the cooling device;
one or more fans or impellers arranged to propel air through the atmospheric water harvester;
ambient temperature and humidity sensors; and
means for controlling the relative amounts of air entering the airflow passageway through the first and second inlets, said means for controlling including a controller that is programmed to control the relative amounts of air entering the airflow passageway through the first and second variable-flow-volume inlets based on measured ambient temperature and humidity so as to achieve a predetermined level of relative humidity of air that reaches to traverse the cooling device.