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Polymer desiccant and system for dehumidified air conditioning

Abstrict

A liquid polymer-salt solution as a desiccant in an air conditioning system comprised of a heat-pipe having its heat absorber section in an outside air inlet duct following water vapor adsorption into the desiccant by a contacter section of a dehumidifier, and the heat-pipe having its heat rejecter section in an exhaust air duct and preferably preceeding water vapor discharge from the desiccant by a regenerater section of the dehumidifier.

Claims

I claim:

1. An air conditioning system having an outside air inlet duct, a conditioned air supply duct into a conditioned space, a return air duct from said conditioned space and a relief exhaust air duct exhausting return air displaced by outside air and with a blower means to transport said outside, supply, return and relief air, and comprised of:

a heat-pipe having a heat absorber section in the inlet duct for removing the heat of adsorption in the dehumidified inlet air therefrom, and a heat rejecter section in the relief exhaust air duct for applying heat to exhaust air flow therethrough,

and an air dehumidifier means for processing a water adsorptive liquid desiccant and having a distribution means for wetting said heat absorber section of the heat-pipe for interface contact of incoming outside air with said liquid desiccant applied thereto to adsorb water vapor therefrom and thereby defining a dehumidifier contacter section, and having a regenerater section in the exhaust air duct following said heat rejecter section for interface contact of relief exhaust air with weakened liquid desiccant from said contacter section and applied thereto by distribution means for removing the heat of adsorption in the dehumidifier air therefrom,

and a heat source means applying heat to the regenerater section to remove water from the liquid desiccant and into the exhaust air.

2. The air conditioning system and dehumidifier means as set forth in claim 1 wherein the incoming outside air flows over the heat-pipe absorber section and dehumidifier contacter section for intimate contact with said liquid desiccant regenerated and drawn from the regenerater section, heat of regeneration being removed by heat exchanger means to a cold source.

3. The air conditioning system and dehumidifier means as set forth in claim 1 wherein the regenerater section is a heat exchanger in circuit with the heat source means and wetted with weakened water saturated desiccant from the contacter section and through which outgoing relief exhaust air flows for intimate contact with said liquid desiccant to remove water therefrom by means of heat transferred thereto by the heat exchanger.

4. The air conditioning system and dehumidifier means as set forth in claim 1 wherein the contacter section discharges weakened water saturated desiccant through a heat exchanger and to the distribution means of the regenerater section, and wherein the regenerater section discharges regenerated heated desiccant through said heat exchanger and to the distribution means of the contacter section for heat transfer into and for regeneration of the first mentioned weakened desiccant.

5. The air conditioning system and dehumidifier means as set forth in claim 1 wherein evaporative cooling means wets the rejecter section of the heat-pipe with evaporative liquid for increasing the cooling effect of the heat absorber section thereof.

6. The air conditioning system and dehumidifier means as set forth in claim 1 wherein a heat exchanger in the inlet duct ahead of the contacter section is in circuit with the heat source means to heat incoming outside air to an optimum range of temperature for humidification and to deter icing conditions.

7. An air conditioning system comprised of a multiplicity of independently operable air conditioner units and each having an outside air inlet duct, a conditioned air supply duct into a conditioned space, a return air duct from said conditioned space and a relief exhaust air duct exhausting return air displaced by outside air and with a blower means to transport said outside supply, return and relief air, and each unit including:

an air dehumidifier means for processing a water vapor adsorptive liquid desiccant and having a contacter section in the inlet duct for interface contact of outside air with said liquid desiccant applied thereto by a distribution means to adsorb water vapor therefrom and thereby weakening the desiccant,

and a heat-pipe having a heat absorber section in the inlet duct following said contacter section for removing the heat of adsorption in dehumified air therefrom, and a heat rejecter section in the relief exhaust air duct,

there being a regenerater section in an outside air transfer duct to remove said adsorbed water vapor from said weakened desiccant from the contacter sections of the multiplicity of conditioner units and returned thereto by said distribution means thereof,

blower means to transport said outside air through transfer duct and through said heat transfer means therein,

and a heat source means applying heat to said heat transfer means for said removal of said water vapor from the liquid desiccant.

8. The air conditioning system and dehumidifier means as set forth in claim 7 wherein the multiplicity of contacter sections discharge weakened water saturated desiccant through a heat exchanger and to the distribution means of the regenerater unit, and wherein the regenerater unit discharges regenerated heated desiccant through said heat exchanger and to the distribution means of the multiplicity of contacter sections for heat transfer into and for regeneration of the first mentioned weakened desiccant.

9. The air conditioning system and dehumidifier means as set forth in claim 7 wherein evaporative cooling means in at least one of said multiplicity of air conditioner units wets the rejecter section of the heat-pipe with evaporative liquid for increasing the cooling effect of the heat absorber section thereof.

10. The air conditioning system and dehumidifier means as set forth in claim 7 wherein a heat exchanger in at least one of said multiplicity of conditioner units is in the inlet duct ahead of the contacter section and is in circuit with the heat source means to heat incoming outside air to an optimum range of temperature for humidification and to deter icing conditions.

11. The air conditioning system and dehumidifier means as set forth in claim 7 wherein the incoming outside air flows through the wetted contacter section of each of the multiplicity of air conditioner units for intimate contact with said liquid desiccant regenerated and drawn from the regenerater unit, heat of regeneration being removed by heat exchanger means to a cold source.

12. The air conditioning system and dehumidifier means as set forth in claim 7 wherein the regenerater unit is a heat exchanger in circuit with the heat source means and wetted with weakened water saturated desiccant from the contacter sections of the multiplicity of air conditioner units and through which outside air is transfered for intimate contact with said liquid desiccant to remove water therefrom by means of heat transferred thereto by the heat exchanger.

13. An air conditioning system comprised for at least one independently operable air conditioner unit and each having an outside air inlet duct, a conditioned air supply duct into a conditioned space, and with a blower means to transport said air, and including;

an air dehumidifier means for processing a water vapor adsorptive liquid desiccant and with a contacter section in the inlet duct for interface contact of outside air with said liquid desiccant applied thereto to adsorb water vapor therefrom and thereby water saturating and weakening the desiccant,

and a heat-pipe having a heat absorber section in the inlet duct following said contacter section for removing the heat of absorption in dehumidified air therefrom, and a heat rejecter section in the relief exhaust air duct,

there being a regenerater means for removing said adsorbed water vapor from said water saturated and weakened desiccant from the contacter section of the at least one conditioner unit and returned thereto for water vapor adsorption thereby,

the said regenerater means being a multi stage desiccant regenerater boiler comprised of at least two stages and each with a pressure control means to operate at successively lower discharge of water vapor driven out of the water saturated and weakened desiccant, whereby desiccant returned to the at least one conditioner unit is strengthened,

and heat source means applying heat to a first stage of the multi stage desiccant regeneration boiler.

14. The air conditioning system and dehumidifier means as set forth in claim 13 wherein water vapor discharge from one stage of the boiler to a successively lower pressure stage is through a heat recovery coil in said successively lower pressure stage and condensed thereby.

15. The air conditioning system and dehumidifier means as set forth in claim 13 wherein water saturated and weakened desiccant counterflows through the stages of the multi stage desiccant regeneration boiler from a stage of lower pressure to a stage of higher pressure.

16. The air conditioning system and dehumidifier means as set forth in claim 13 wherein the discharge of the water vapor driven out of the water saturated weakened desiccant is condensed and exhausted through a heat exchanger for transfer of heat into the weakened desiccant entering into the multi stage desiccant regeneration boiler.

17. The air conditioning system and dehumidifier means as set forth in claim 13 wherein the discharge of strengthened desiccant from the multi stage desiccant regeneration boiler is through a heat exchanger for transfer of heat into the weakened desiccant entering into the multi stage desiccant regeneration boiler.

18. The air conditioning system and dehumidifier means as set forth in claim 13 wherein the heat source means is at a temperature to establish a water vapor discharge pressure within a first stage of the multi stage desiccant regeneration boiler.

Description

BACKGROUND OF THE INVENTION

This invention relates to air conditioning wherein the intake of outside air is dehumidified. Heretofore, the desiccants employed have been expensive and because of their corrosive nature the dehumidifying section of air conditioning equipment has been fabricated of exceedingly expensive corrosive resistant materials, for examples calcium chloride or lithium chloride desiccants employing copper-nickel steel equipment is the usual requirement. Accordingly, it is a primary object of this invention to provide a relatively inexpensive and less corrosive desiccant, and a desiccant that is economically effective and which is adapted to use in relatively inexpensive equipment made of commercial grade materials such as steel that is protectively coated as by a paint or sealant, plating, or galvanizing and the like. It is cost effective dehumidification which is an object of this invention, all of which is accomplished without change to the downstream refrigeration and/or heating equipment.

There are a number of materials known to be useful as desiccants and particularly polymers proposed to be used as solids adapted to absorb water and to be regenerated as by drying for repeated use. However, the use of solid desiccant involves equipment implementation that can become bulky and oversized due to the nature of volume increase by the cube of the structural dimensions. With solid polymer the composition of the desiccant in a substrate is fixed. Therefore, the water uptake is dependent only upon temperature. However, with an aqueous polymer solution the liquid concentration can be variable, so that the water uptake is controllable, since the vapor pressure, concentration and temperature are all adjustable so as to maximize their functions. It is therefore an object of this invention to avoid objectionable size increase in the equipment by employing liquid polymers which avoid the same as capacity requirements increase, since they are fluid and are therefore more versatile in their applications. Such polymers which are feasible to be used as packed desiccants are:

Polystyrene sulfonic acids sodium salt

Polyacrylic acid ammonium salt

Poly (methacrylic acid) sodium salt

Poly (n-vinylacetamide vinyl sulfonate) sodium salt

Polyacrylic acid sodium salt

Cellulose sulfonate sodium salt

Methyl cellulose

However, it is a liquid desiccant of polymer material with which this invention is concerned, and to this end it is an object to provide the same in the form of hygroscopic fluids as a desiccant, rather than in the form of solid salts.

Water vapor sorption by polymers is a recognized advantage, however there is criticality involved in the salt to be employed therewith, the water uptake capability being most important. The ion-dipole interaction is therefore to be considered, reference being made to FIGS. 3a, 3b and 3c of the drawings, which illustrate the comparisons between the use of Lithium, Sodium and Potassium. It becomes apparent that the Lithium ion Li+ accommodates a far greater amount of water, of the three, due to its small cationic size as compared with either Sodium Na+ Potassium K+. The atomic weight and corresponding cationic size of various elements are considered, as follows:

______________________________________ Li Lithium 6.9 Na Sodium 23 K Potassium 39 Ca Calcium 40 Ca Cesium 133 ______________________________________

Therefore, it is an object of this invention to employ any one of the known salts in the sulfonation of the aforementioned polymers to be employed in a liquid form as a hygroscopic liquid, especially as a desiccant. Accordingly, Polystyrene Sulfonic Acid Lithium Salt Solution or PSSALS is a preferred embodiment herein (see FIG. 5b).

It is an object of this invention to implement the advantages of a polymer-salt solution in dehumidification equipment, as a low cost unit or section of equipment applicable to existant refrigeration air conditioning equipment, without major change thereto. Air conditioning involves generally, an outside air supply, a supply air discharge into a building interior, return air intake from the building interior, and a relief air discharge. The polymer-salt solution dehumidifier of the present invention is adapted to the outside air intake and to the relief air discharge of the existent air conditioning equipment. It is an object of this invention to advantageously employ the outside supply air intake temperature for desiccant treatment. It is also an object of this invention to advantageously employ a heat-pipe to extract heat after dehumidifier intake section herein disclosed replaces an air intake or power section of usual equipment and is preferably attached to a blower section unit that separates the relief air from the return air, as shown.

An air conditioning system involves the discharge of relief air that is replaced by outside supply air. The volume ratio of these two columns of air varies as a result of variations in leakage from the conditioned air spaced involved, the relief air being stale interior air retrieved at a place or places of higher interior temperature and where stale air exists. Consequently, relief air is substantially warmer than supply air (the conditioned air), it being an object of this invention to advantageously employ warmer relief air before its discharge as exhaust air, by dissipating its usable heat energy through the regenerater section of the dehumidifier. It is still another object of this invention to advantageously employ the heat energy rejected by the heat pipe, or pipes, for this purpose, as disclosed in each of the embodiments of this invention as later described.

In a second embodiment of this invention, FIG. 4 the adsorption element of the dehumidifier is a heat exchanger over which the polymer-salt solution is wetted and through which a coolant is circulated for reduced temperature intake air into the air conditioning equipment. In practice, the coolant is controlled and circulated by a pump, over or through a heat exchanger, and chilled or cooled as by means of an evaporative cooling tower (employing water). The heat-pipe relationship remains the same as in the first embodiment.

In a third embodiment of this invention, FIG. 6 the adsorption element of the dehumidifier is the absorber section or hot end of the heat-pipe and over which the polymer-salt solution is wetted for water vapor sorption and through which the heat-pipe refrigerant recirculates for heat absorption. There is a simultaneous heating effect and cooling effect on the outside supply air, said air being heated as a result of the water vapor sorption by the polymer-salt solution while being cooled as a result of heat adsorption by the hot end of the heat-pipe. It is to be understood that the use of a hygroscopic desiccant liquid involves regeneration through the application of heat, which is shown herein generally as a supplemental heat source, all according to state of the art processes. In accordance with this invention, regeneration is by means in the discharge of relief air over the heat rejector section or cold end of the heat-pipe.

In a fourth embodiment of this invention, FIG. 9 a central regenerater unit services a multiplicity of dehumidifier contactor sections. That is, a multiplicity of dehumidifier means, each serving an independent air conditioning unit, commingles weakened desiccant to be strengthened by a single regenerater section or unit. This combination reduces the complexity of the dehumidifier means operable with each air conditioner unit, and makes possible the use of a larger most efficient regenerater unit for cost efficient operation.

In a fifth embodiment of this invention, FIG. 10 the regenerater section is a self contained and self operable unit wherein heat is the prime mover directly applied to the water saturated desiccant without resort to contact with blower motivated air. Reference is made to the polymer-salt desiccant solution disclosed herein as the preferred hygroscopic liquid for the adsorption of water vapor. This preferred desiccant is known to be more viscous than the usual prior art desiccant such as Lithium Chloride, and through spray bar distribution is practical in the contacter section of a dehumidifier means, regeneration by means of spray bar and interface heat application presents liquid handling problems, because of the higher viscosity. It is an object of this invention, therefore, to directly process the weakened higher viscosity desiccant through a multi effect boiler concentrater, using the direct application of heat in a first high pressure stage followed by at least one or more lower pressure stages and with a counter flow of desiccant from which water vapor is driven out of the weakened water saturated liquid and returned to the contacter section or sections as strengthened desiccant.

SUMMARY OF THE INVENTION

A polymer-salt solution is provided as the desiccant in the form of a hygroscopic liquid than can be processed and transported most efficiently in cost effective dehumidification equipment. There are a number of salts that may be used in the formation of the desiccant provided, preferably one of small cationic size such as Lithium, Sodium or Potasium. The polymer materials do not vaporize and are reasonably stable for the purpose intended, and they are sulfonated and retained in solution and liquid state for transport between and effective processing at the contacter section and regenerate section of the dehumidifier. The preferred desiccant is sulfonated Lithium, for its small dipole configuration as illustrated in FIG. 3a of the drawings, a cost effective material that is, for example, approximately two thirds the cost of a comparable aqueous Lithium Chloride solution, when prepared for the purpose under consideration. And, by employing a polymer-salt solution as specified herein, corrosive effect upon the equipment is minimized to the extent that cost effective materials can now be used in their construction. Accordingly, commercial grade low cost materials can be used to replaced high grade cooper-nickel materials.

The aforesaid employment of polymer-salt solutions for dehumidification is advantageously combined herein with the function of heat-pipe means, in a system that has no adverse effect on the outside air intake to the downstream air conditioning equipment, but rather a beneficial effect. A feature of this invention is that the dehumidified air discharge is through heat-pipe means that removes heat added to the outside intake air in the preceeding process of adsorption. Another feature of this invention is the use of relief air discharge over the heat rejecter portion of the heat-pipe means whereby heat energy in the relief air is advantageously employed and supplemented by a controllable heat source to operate the regenerater section of the dehumidifier.

It is still another object of this invention to combine a dehumidifier and a heat-pipe for simultaneous dehumidification and heat rejection from outside intake air, ahead of refrigeration or heating by downstream equipment. In accordance with this invention, the heat absorber section of the heat-pipe means serves as the adsorption section of the dehumidifier, its heat transfer surface being wetted with the desiccant, preferably with the sulfonated Lithium solution as described. In the summer mode of operation, outside dehumidified air is pre-cooled. In the winter mode of operation, outside dehumidified air is permitted to add heat through inherent reversal of the heat-pipe. The downstream air conditioning equipment operates in either the summer of winter mode.

The regeneration of weakened desiccant can be conducted on a unit basis with a regenerater section assigned to each contacter section, or on a central service basis with a common return to and supply from a remoted regenerate unit of most efficient design. Further, a most significant feature of this invention is the higher viscosity of the polymer-salt solution used as the desiccant, wherein a direct multi stage boiler regenerater section or unit is most efficient, thereby eliminating the usual prior art liquid to air interface contact for vaporization and water vapor discharge.

The foregoing and various other objects and features of this invention will be apparent and fully understood from the following detailed description of the typical preferred forms and applications thereof, throughout which description reference is made to the accompanying drawings.

THE DRAWINGS

FIG. 1 is a longitudinal side elevation illustrating the system of the present invention, with the dehumidifier section installed ahead of a downstream air conditioner.

FIG. 2 is an enlarged diagram showing a first embodiment wherein a heat-pipe reduces outside intake air temperature and utilizes the discharge of inside relief air.

FIGS. 3a, 3b and 3c illustrate the comparison in the cationic size of Lithium, Sodium and Potassium ions, the preferred salts use herein to form the polymer-salt solution as a desiccant.

FIG. 4 is a diagram similar to FIG. 2 showing a second embodiment, wherein the adsorption section of the dehumidifier is a heat exchanger that cools the outside intake air.

FIG. 5a and 5b are diagrams that illustrate Hydrogen and Lithium anionic polymers, respectively.

FIG. 6 is a diagram similar to FIGS. 2 and 4 showing a third embodiment, wherein the contacter section of the dehumidifier is combined with the heat absorber section of the heat-pipe, and with heat rejection into the relief air that is exhausted through the regenerator section of the dehumifier.

FIG. 7 is a perspective fragmentary section of a heat-pipe configuration as it is employed throughout this disclosure.

FIG. 8 is a sectional view showing the finned feature of the heat-pipe for efficient heat transfer.

FIG. 9 illustrates a multiplicity of downstream air conditioner units and each preceeded by a dehumidifier section, and wherein the multiplicity of dehumidifier sections is serviced by a central regenerater unit.

And FIG. 10 illustrates a desiccant regeneration multi stage boiler servicing at least one or more downstream air conditioning systems or units, and each of which has a contacter section for dehumidifying incoming outside air.

PREFERRED EMBODIMENTS

Referring now to the drawings, FIG. 1 illustrates typical refrigeration air conditioning equipment comprised of a power return section 10 a filter section 11 a coil section 12 a blower section 13 and a diffuser and final filter section 14. The necessary refrigeration compressor and condenser (not shown) are included in the coil section 12 or they are external. The power section 10 is preferably a blower section that includes means that separates return air RA into recirculated supply air SA which is supplemented by incoming outside air OSA air and into relief air RE which is exhausted to outside atmosphere. That is, a portion of the conditioned interior air is discharged as relief air RE, and it is replaced by new incoming outside air OSA. In practice, the discharge temperature of incoming outside air OSA into the power return section 10 is proximate to the outside air temperature, while the discharge temperature of relief air is that of the warmer interior air. The sections 10-14 discharge supply air SA into the conditioned interior at a temperature set by thermostat control means (not shown). The downstream air conditioning equipment is state of the art, having an intake duct at 15 to receive dehumidified outside air, and a discharge duct 16 to deliver conditioned supply air into a building structure. The power return section 10 is in open communication with the intake duct 15 and receives dehumidified outside air OAS therefrom. The power section 10 is characterized by damper means or the like (not shown) that separates a portion of the return air for discharge to atmosphere via a discharge duct 17 corresponding in capacity to an intake duct 18 (see FIG. 1), ducts 17 and 18 opening at the interface of power section 10 with the dehumidifier contactor D and regenerator section R later described.


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