Chemical energy storage system

Abstract

A system for storing chemical energy comprises first and second vessels, the first containing a liquid solution of an alkali or alkaline earth metal hydroxide, halide, or thiocyanate, or ammonium halide or thiocynate at an initial concentration of between about 30% to abotu 80%, by weight, the second vessel containing liquid, a space about the liquid in each vessel and a conduit communicating between the spaces having a valve for selectively allowing liquid vapor to pass between the spaces, means for heating the solution to a temperature above about 80° F., means for cooling the liquid to a temperature below about 55° F., and heat exchange means for transferring heat from the heated solution and for transferring heat to the cooled liquid. Water is the preferred liquid although ammonia, lower alcohols, and polyols such as glycerol, glycols, polyglycols, glycol ethers, lower aliphatic amines and alkanol amines, and mixtures thereof, may be used.

I claim: 
     
       1. Apparatus for .[.transferring heat.]. .Iadd.alternately charging and discharging thermal energy .Iaddend.comprising a first vessel containing a liquid solution of a compound selected from the group consisting of alkali and alkaline earth metal hydroxide, halide and thiocyanate, ammonium halide, .Iadd.ammonium metal halide .Iaddend.and thiocyanate, and mixtures thereof, said solution having an initial concentration of between about 30% and about 80% by weight of said compound, said liquid selected from the group consisting of water, ammonia, an alcohol having between 1 and 8 carbon atoms, glycerol, glycols, polyglycols, glycol ethers, aliphatic amines and alkanol amines having between 1 and about 6 carbon atoms, and mixtures thereof, and a first space above the level of said liquid solution and means for pumping said liquid solution to distribution means for directing said liquid solution into said first space,   a second vessel containing said liquid without said compound therein, and a second space above the level of said liquid and means for pumping said liquid to distribution means for directing said liquid solution into said second space,   both said first and second vessels being closed to atmosphere and capable of holding a vacuum,   conduit means communicating between said first space and second space for allowing liquid vapor and pressure changes to pass therebetween, and valve means cooperating with said conduit means for terminating communication between said spaces,   heating means .[.for.]. .Iadd.capable of .Iaddend.heating said solution to a temperature of above about .Badd..[.90°.]..Baddend. .Iadd.85° .Iaddend.F., and cooling means .[.for.]. .Iadd.capable of .Iaddend.cooling said liquid to a temperature below about 55° F. .Iadd.during said charging .Iaddend.,   first heat exchange means cooperating with said first vessel for transferring heat from heated solution therein, and second heat exchange means cooperating with said second vessel for transferring heat to liquid therein .Iadd.during said discharging. .Iaddend.   
     
     
       2. Apparatus of claim said first and second vessels comprise first and second chambers in a divided tank, respectively. 
     
     
       3. Apparatus of claim 2 wherein said conduit means comprises port means communicating between said first and second spaces, and wherein said valve means opens and closes said port means 
     
     
       4. Apparatus of claim 1 including first pipe means and first pump means for directing said solution between said first vessel and said first heat exchange means, and second pipe means and second pump means for directing said liquid between said second vessel and said second heat exchange means. 
     
     
       5. Apparatus of claim 4 wherein said first heat exchange means comprises a heat pump condenser, and said second heat exchange means comprises a heat pump evaporator. 
     
     
       6. Apparatus of claim 4 wherein said .[.first heat exchanger.]. .Iadd.heating .Iaddend.means comprises waste heat or solar heat means. 
     
     
       7. Apparatus of claim 1 wherein said first heat exchange means includes a first heat exchange pipe exposed in said first space and wherein said distribution means directs said solution over the first heat exchange pipe in said first space. 
     
     
       8. Apparatus of claim 7 including spray means for spraying said solution over said first heat exchange pipe. 
     
     
       9. Apparatus of claim 7 wherein said first heat exchange pipe comprises a condenser coil. 
     
     
       10. Apparatus of claim 1 wherein said second heat exchange means includes a second heat exchange pipe exposed in said second space and wherein said distribution means directs said liquid over said second heat exchange pipe. 
     
     
       11. Apparatus of claim 10 including spray means for spraying said liquid over said second heat exchange pipe. 
     
     
       12. Apparatus of claim 10 wherein said second heat exchange pipe comprises an evaporator coil. .[. 
     
     
       13.  Apparatus of claim 1 wherein said first heat exchange means include evaporative or air to air cooling means and first supplemental heat transfer means comprising a first conduit loop having heat transfer liquid therein and a pump cooperating therewith for pumping said heat transfer liquid through said first conduit loop, said first conduit loop extending between said first space and said evaporative or air to air cooling means..]. 
     
     
       14. Apparatus of claim .[.13.]. .Iadd.15 .Iaddend.including spray means for spraying said solution over said first conduit loop in said first space. 
     
     
       15. Apparatus for .[.of claim 13.]. .Iadd.alternately charging and discharging thermal energy comprising a first vessel containing a liquid solution of a compound selected from the group consisting of alkali and alkaline earth metal hydroxide, halide and thiocyanate, ammonium halide, metal halide and thiocyanate, and mixtures thereof, said solution having an initial concentration of between about 30% and about 80%, by weight of said compound, said liquid selected from the group consisting of water, ammonia, an alcohol having between 1 and 8 carbon atoms, glycerol, glycols, polyglycols, glycol ethers, aliphatic amines and alkanol amines having between 1 and about 6 carbon atoms, and mixtures thereof, and a first space above the level of said liquid solution and means for pumping said liquid to distribution means for directing said liquid into said first space,   a second vessel containing said liquid without said compound therein, and a second space above the level of said liquid and means for pumping said liquid to distribution means for directing said liquid into said second space,   both said first and second vessels being closed to atmosphere and capable of holding a vacuum,   conduit means communicating between said first space and said second space for allowing liquid vapor and pressure changes to pass therebetween, and valve means cooperating with said conduit means for terminating communication between said spaces,   heating means capable of heating said solution to temperature of above about 85° F., and cooling means capable of cooling said liquid to a temperature below about 55° F., during said charging,   first heat exchange means cooperating with said first vessel for transferring heat from heated solution therein, and second heat exchange means cooperating with said second vessel for transferring heat to liquid therein during said discharging,   wherein said first heat exchange means include evaporative or air to air cooling means and first supplemental heat transfer means comprising a first conduit loop having heat transfer liquid therein and a pump cooperating therewith for pumping said heat transfer liquid through said first conduit loop, said first conduit loop extending between said first space and said evaporative or air to air cooling means, and.Iaddend.   wherein said second heat exchange means includes a heat pump evaporator and second supplemental heat transfer means comprising a second conduit loop having a heat transfer liquid therein and a pump cooperating therewith for pumping said heat transfer liquid through said second conduit loop said second conduit loop extending between said second space and said evaporator.   
     
     
       16. Apparatus of claim 15 including spray means for spraying said liquid over said second conduit loop in said second space. 
     
     
       17. A .[.heat exchange.]. process .Iadd.for alternately storing and discharging thermal energy .Iaddend.utilizing the apparatus of claim 1 comprising: (a) opening said valve means,   (b) heating said solution in said first vessel to a temperature of above about 85° F. .Iadd.by exposing said solution to said heating means .Iaddend.and evaporating liquid therefrom, directing the liquid vapor from the space in said first vessel to the space in said second vessel through said conduit means,   concurrently cooling the liquid in said second vessel to a temperature below about 55° F, .Iadd.by exposing said liquid to said cooling means .Iaddend.and condensing the .[.water.]. .Iadd.liquid .Iaddend.vapor in the space therein and continuing said heating and cooling until the concentration of said material in said first vessel is between about 6% and about 25% greater than said initial concentration,   (c) terminating said heating of said solution and said cooling of said liquid and closing said valve means thereby closing communication between said spaces in said first and second vessels,   (d) selectively opening said valve whereby liquid therein is evaporated thereby cooling said liquid in said second vessel as liquid vapor pressure differential between said first and second vessel is eliminated,   (e) exposing said liquid in said second vessel to heat exchange means and pumping said liquid to said distribution means and spraying said pumped liquid into said second space .[.;.]..Iadd., .Iaddend.and   (f) concurrently with step (e) exposing said solution in said first vessel to heat exchange means and pumping said solution to said distribution means and spraying said pumped solution into said first space.   
     
     
       18. Process of claim 17 wherein said solution is heated to above .Badd..[.80°.]..Baddend. .Iadd.85° .Iaddend.F. in step (b) by directing said solution to a heat pump condenser or solar or waste heat source and exposing said solution to heated elements thereof. 
     
     
       19. Process of claim 18 wherein said liquid is cooled below about 55° F. by directing said liquid to a heat pump .Iadd.or air conditioning .Iaddend.evaporator and exposing said liquid to cooled elements thereof. 
     
     
       20. Process of claim 17 wherein said liquid is cooled to below about 55° F. in step (b) by directing said liquid to a heat pump .Iadd.or air conditioning .Iaddend.evaporator and exposing said liquid to cooled elements thereof. 
     
     
       21. Process of claim 20 wherein said cooled liquid from step (e) is directed to a heat exchange evaporator for cooling elements thereof. 
     
     
       22. Process of claim 17 comprising providing elements of said first heat exchange means in said first space and providing elements of said second heat exchange means in said second space and spraying said liquid over said elements of said second heat exchange means in step (e) and spraying said solution over said elements of said first exchange means in step (f). 
     
     
       23. Process of claim 22 comprising providing said heat exchange elements in said second space and spraying said elements with said liquid. .Iadd. 
     
     
       24.  Apparatus of claim 1 wherein said liquid comprises water or a mixture of water and ammonia, and said compound is selected from the group consisting of an alkali and alkaline earth metal hydroxide, calcium chloride, calcium bromide, and mixtures thereof. .Iaddend. .Iadd.25. Apparatus of claim 1 wherein said cooling means for cooling said liquid to a temperature below about 55° F. comprises a heat pump or air conditioning evaporator. .Iaddend. .Iadd.26. Apparatus of claim 1 wherein said liquid comprises ammonia, and wherein said compound is selected from the group consisting of ammonium halide, ammonium metal halide and 
     
     
        ammonium thiocyanate. .Iadd.27.  Apparatus for alternately charging and discharging thermal energy comprising: a first vessel containing a liquid solution of a compound selected from the group consisting of alkali and alkaline earth metal hydroxide, halide and thiocyanate, ammonium halide and thiocyanate, and mixtures thereof, said solution having an initial concentration of between about 30% and about 80%, by weight of said compound, said liquid selected from the group consisting of water, ammonia, an alcohol having between 1 and 8 carbon atoms, glycerol, glycols, polyglycols, glycol ethers, aliphatic amines and alkanol amines having between 1 and about 6 carbon atoms, and mixtures thereof, and a first space above the level of said liquid solution and means for pumping said liquid solution to distribution means for directing said liquid solution into said first space,   a second vessel containing said liquid without said compound therein, and a second space above the level of said liquid and means for pumping said liquid to distribution means for directing said liquid into said second space,   both said first and second vessels being closed to atmosphere and capable of holding a vacuum,   conduit means communicating between said first space and said second space for allowing liquid vapor and pressure changes to pass therebetween, and valve means cooperating with said conduit means for terminating communication between said spaces,   means for charging said thermal energy comprising heating means capable of heating said solution to a temperature of above about 85° F., and cooling means capable of cooling said liquid to a temperature below about 35° F.,   means for discharging said thermal energy comprising first heat exchange means cooperating with said first vessel for transferring heat from heated solution therein, and   second heat exchange means cooperating with said second vessel for utilizing the thermal energy benefit of the cooled liquid o provide cooling to air conditioner or heat pump cooling heat exchange means during   
     
     
        said discharging. .Iaddend. .Iadd.28.  Apparatus of claim 27 wherein said cooling means comprises a heat pump or refrigeration system evaporator. 
     
     
        .Iaddend. .Iadd.29.  A method for utilizing the apparatus of claim 27 comprising: charging thermal energy to said apparatus at night or during period of reduced demand for electrical power by opening said valve means, heating said solution in said first vessel to a temperature of above about 85° F. and evaporating liquid therefrom, directing the liquid vapor from the space in said first vessel to the space in said second vessel through said conduit means, concurrently cooling the liquid in said second vessel to a temperature below about 55° F. and condensing the water vapor in the space therein,   terminating said heating of said solution and said cooling of said liquid and closing said valve means thereby closing communication between said spaces in said first and second vessels;   discharging thermal energy from said apparatus during the day or period of higher demand of electrical power by exposing said cooled liquid in said second vessel to air conditioner or heat pump cooling heat exchange means whereby said cooled liquid becomes heated by said exposure, and   pumping said liquid to said distribution means and spraying said pumped liquid into said second space and opening said valve whereby heated liquid therein is evaporated thereby cooling said liquid in said second vessel as liquid vapor pressure differential between said first and second vessels is eliminated, exposing said solution in said first vessel to heat exchange means and pumping said solution to said distribution means and spraying said pumped solution into said first space. .Iaddend. .Iadd.30. Method of claim 29 wherein said liquid is cooled to a temperature of below about 35° F. during said charging. .Iaddend. .Iadd.31. Method of claim 30 wherein said solution is heated to between about 85° F. and about 130° F. during said charging. .Iaddend. .Iadd.32. Method of claim 31 wherein heating said solution during said charging is carried out by exposing said solution to a heat exchanger of a heat pump or refrigeration apparatus condenser. .Iaddend. .Iadd.33. Method of claim 31 wherein said cooling said liquid during said charging is carried out by exposing said liquid to a heat exchanger of an evaporator of a heat pump or air conditioning system. .Iaddend. .Iadd.34. Method of claim 31 including continuing said heating and cooling during said charging until the concentration of said compound in said first vessel is between about 6% and about 25% greater than said initial concentration. .Iaddend.   
     
     
        .Iadd. 5.  Apparatus alternately storing and discharging thermal energy comprising a first vessel containing a liquid solution of a compound selected from the group consisting of alkali and alkaline earth metal hydroxide, halide and thiocyanate, ammonium halide, metal halide and thiocyanate, and mixtures thereof, said solution having an initial concentration of between about 30% and about 80%, by weight of said compound, said liquid selected from the group consisting of water, ammonia, an alcohol having between 1 and 8 carbon atoms, glycerol, glycols, polyglycols, glycol ethers, aliphatic amines and alkanol amines having between 1 and about 6 carbon atoms, and mixtures thereof, and a first space above the level of said liquid solution and means for pumping said liquid solution to distribution into said first space, a second vessel containing said liquid without said compound therein, and   a second space above the level of said liquid and means for pumping said liquid to distribution means for directing said liquid into said second space,   both said first and second vessel being closed to atmosphere and capable of holding a vacuum,   conduit means communicating between said first space and said second space for allowing liquid vapor and pressure changes to pass therebetween, and valve means cooperating with said conduit means for terminating communication between said spaces,   heating means for heating said solution to a temperature of above about 85° F., and cooling means comprising a heat pump or air conditioning system evaporator for cooling said liquid to a temperature below about 55° F.,   first heat exchange means cooperating with said first vessel for transferring heat from heated solution therein, and second heat exchange means cooperating with said second vessel for transferring heat to liquid therein. .Iaddend.