Water extraction from air and desalination

Abstract

This invention is a water producer that extracts water from the air. One embodiment of the invention adiabatically compresses and heats the air. The heated air is cooled through a counter-flow heat exchanger so that it becomes supersaturated and water condenses. The air is then cooled further and passed back through the heat exchanger to recover its former heat. It then passes through an adiabatic expander to recover energy. A second embodiment utilizes a unique isothermal compressor/expander to compress the humid air isothermally so that the air becomes supersaturated with water, and the water condenses. The air is then cooled to remove the heat of condensation of the water and returned to the isothermal compressor/expander to recover energy. A third embodiment draws in humid air through a counter-flow heat exchanger to cool it down below its dew point so that water is collected. The air is then cooled adiabatically and passed back through the counter-flow heat exchanger and on to a compressor, which compresses the air back to ambient pressure and pushes the air out. These embodiments can be used to desalinate seawater, brackish water, or desiccant aqueous solutions by having a humidifier evaporate water from the liquids to make the input air to the water producer very humid.

1 . A water and power producing system comprising:
 an adiabatic compressor for compressing and thus increasing the temperature of humid air; and   a counter-flow heat exchanger to cool the compressed humid air; and   a condenser to condense water from the compressed and cooled humid air; and   a cooler to further cool the humid air and condense more water and to provide cooling to the cool end of the counter-flow heat exchanger; and   a pipe to conduct the cool air back to the cool end of counter-flow heat exchanger; and   a heater to heat the air further after the air leaves the counter-flow heat exchanger, which heater may receive heat from solar energy or other energy source; and   an adiabatic expander for expanding the air after it has flowed back through the counter-flow heat exchanger and become re-heated;   a drain to drain condensed water; and   valves to control the flow of air;   wherein the adiabatic compressor draws in ambient air, compresses it, and forces it into the counter-flow heat exchanger, where the air cools and becomes super-saturated with water vapor, some of the water vapor condenses in the condenser and flows out the drain, the air flows to the cooler, where it is cooled further and more water is condensed and flows out the drain, the air flows back through the counter-flow heat exchanger to be heated as it cools the air that flows the opposite direction, the re-heated air flows through the heater to be further heated and flows into an adiabatic expander that extracts mechanical energy from the air as the air expands, which mechanical energy may be used to drive an electric generator, and the adiabatic expander pushes the air into the atmosphere.   
   
   
       2 . A water and power producing system according to  claim 1 , wherein the cooler is an adiabatic expander cooler that extracts additional energy from the air as it cools the air and condenses water, which is drained through the drain. 
   
   
       3 . A water and power producing system according to  claim 1 , wherein the adiabatic compressors and adiabatic expanders are reciprocating piston-in-cylinder type compressors and expanders. 
   
   
       4 . A water and power producing system according to  claim 1 , wherein the adiabatic compressors and adiabatic expanders are rotating piston type compressors and expanders. 
   
   
       5 . A water and power producing system according to  claim 1 , wherein the adiabatic compressors and adiabatic expanders are turbine type compressors and expanders. 
   
   
       6 . A water and power producing system according to  claim 1 , wherein the adiabatic compressors and adiabatic expanders are bellows type compressors and expanders. 
   
   
       7 . A water producing system comprising:
 an isothermal compressor/expander for compressing humid air and thus increasing the relative humidity of the air, and for expanding the air after some water has been removed from the air; and   a condenser to condense water from the compressed air; and   a cooler to further cool the humid air and condense more water and to provide cooling to remove the latent heat of condensation of the water and to keep the isothermal compressor/expander cool; and   a pipe to conduct the cool air back to the isothermal compressor/expander; and   a drain to drain condensed water; and   valves to control the flow of air;   wherein the isothermal compressor/expander draws in ambient air, compresses it, and forces it into the condenser, where some of the water vapor condenses in the condenser and flows out the drain, the air flows to the cooler, where it is cooled further and more water is condensed and flows out the drain, the air flows back into the isothermal compressor/expander that extracts mechanical energy from the air as the air expands, and the isothermal compressor/expander pushes the air into the atmosphere.   
   
   
       8 . A water producing system according to  claim 7 , wherein the isothermal compressor/expander consists of:
 a piston contained in a cylinder; and   closely spaced tapered plates or tapered concentric circular forms attached to the face of the piston for the purpose of receiving heat from compressing air and supplying heat to expanding air to keep the air close to isothermal; and   closely spaced tapered plates or tapered concentric circular forms attached to the bottom of the cylinder for the purpose of receiving heat from compressing air and supplying heat to expanding air to keep the air close to isothermal;   wherein the closely spaced tapered plates or tapered concentric circular forms attached to the face of the piston fit between the closely spaced plates attached to the bottom of the cylinder when the piston approaches the bottom of the cylinder.   
   
   
       9 . A water producing system according to  claim 7 , wherein the isothermal compressor/expander consists of:
 two rotating pistons within a housing, which rotating pistons roll together to form a seal; and   closely spaced tapered plates or tapered concentric circular forms attached to the inside of the rotating pistons for the purpose of receiving heat from compressing air and supplying heat to expanding air to keep the air close to isothermal; and   closely spaced tapered plates or tapered concentric circular forms attached to the housing for the purpose of receiving heat from compressing air and supplying heat to expanding air to keep the air close to isothermal;   wherein the closely spaced tapered plates or tapered concentric circular forms attached to first side of the rotating pistons fit between the closely spaced tapered plates or tapered concentric circular forms attached to the first side of the housing when the rotating piston rotate toward the first side of the housing, and wherein the closely spaced tapered plates or tapered concentric circular forms attached to the second side of the rotating pistons fit between the closely spaced plates or tapered concentric circular forms attached to the second side of the housing when the rotating piston rotate toward the second side of the housing.   
   
   
       10 . A water producing system according to  claim 7 , wherein the isothermal compressor/expander consists of:
 a bellows compressor/expander; and   closely spaced tapered plates or tapered concentric circular forms attached to the inside top of the bellows for the purpose of receiving heat from compressing air and supplying heat to expanding air to keep the air close to isothermal; and   closely spaced tapered plates or tapered concentric circular forms attached to the bottom of the bellows for the purpose of receiving heat from compressing air and supplying heat to expanding air to keep the air close to isothermal;   wherein the closely spaced tapered plates or tapered concentric circular forms attached to the top of the bellows fit between the closely spaced plates or tapered concentric circular forms attached to the bottom of the bellows when the top of the bellows approaches the bottom of the bellows.   
   
   
       11 . A water producing system according to  claim 7 , wherein the cooler is an adiabatic expander cooler that extracts additional energy from the air as it cools the air and condenses water, which is drained through the drain. 
   
   
       12 . A water and power producing system according to  claim 1 , wherein a humidifier provides high humidity to the air that is drawn into the water and power producing system, which humidifier has a plurality of slanted sheets on which a film of seawater, brackish water, or desiccant aqueous solutions flow while the air flows over the film of liquid to absorb the water vapor from the liquid. 
   
   
       13 . A water producing system according to  claim 7 , wherein a humidifier provides high humidity to the air that is drawn into the water producing system, which humidifier has a plurality of slanted sheets on which a film of seawater, brackish water, or desiccant aqueous solutions flow while the air flows over the film of liquid to absorb the water vapor from the liquid. 
   
   
       14 . A water and power producing system according to  claim 1 , wherein a humidifier provides high humidity to the air that is drawn into the water producing system, which humidifier has an upper and lower chamber with a slanted sheet separating the two chambers on which sheet a film of seawater, brackish water, or desiccant aqueous solutions flow while the air flows over the film of liquid to absorb the water vapor from the liquid, and wherein heat is supplied from the lower chamber to help evaporate the water, which heat is provided by air flowing from the condenser of the water producing system, and which air flows out of the lower chamber after having been cooled back to the counter-flow heat exchanger. 
   
   
       15 . A water producing system according to  claim 7 , wherein a humidifier provides high humidity to the air that is drawn into the water producing system, which humidifier has an upper and lower chamber with a slanted sheet separating the two chambers on which sheet a film of seawater, brackish water, or desiccant aqueous solutions flow while the air flows over the film of liquid to absorb the water vapor from the liquid, and wherein heat is supplied from the lower chamber to help evaporate the water, which heat is provided by air flowing from the condenser of the water producing system, and which air flows out of the lower chamber after having been cooled back to the isothermal compressor/expander. 
   
   
       16 . A water producing system comprising:
 a counter-flow heat exchanger to cool inflowing humid air; and   a condenser to condense water from the cooled humid air; and   a an adiabatic expander cooler to further cool the air and condense more water and to provide cooling to the cool end of the counter-flow heat exchanger; and   a pipe to conduct the cool air from the adiabatic expander cooler back to the cool end of counter-flow heat exchanger; and   an adiabatic compressor for compressing the air after it flows back through the counter-flow heat exchanger and becomes re-heated;   a drain to drain condensed water;   wherein the adiabatic expander cooler draws in ambient air through the counter-flow heat exchanger, which cools the air, and draws the air through the condenser where water condenses and flows out the drain, and the adiabatic expander cooler expands the air, further cooling it and condensing more water, which water flows out the drain, and the adiabatic expander cooler forces the air through the pipe back into the counter-flow heat exchanger to be heated as it cools the air that flows the opposite direction, the re-heated air flows into an adiabatic compressor that compresses the air and pushes the air into the atmosphere.