MOISTURE SEPARATION SYSTEM
A moisture separating system includes a first heat pump, a liquid source in thermal communication with a heat absorption section of the heat pump, and a source of a gas to be treated. The system also includes a hydrophilic nanoporous membrane comprising a first side that receives a flow of gas from the gas source and a second side that receives a flow of liquid from the liquid source.
This patent application claims priority to U.S. Provisional Application No. 62/448,693, filed Jan. 20, 2017, which is incorporated herein by reference in its entirety.
BACKGROUNDMoisture can be separated or removed from a gas for various purposes such as industrial processes or air conditioning.
For example, conventional vapor compression air conditioning (VCC) systems generally do not provide direct control of humidity of conditioned air. However, humidity control is often required, and is provided with VCC systems by direct expansion of refrigerant to a temperature below the dew point of the air being conditioned. This results in removal of moisture from the air by condensation of atmospheric moisture at the VCC system evaporator. Air flow leaving the evaporator coils is typically near the refrigerant saturation temperature for a given suction pressure, which is often colder than the temperature needed for conditioned air, necessitating re-heating to provide conditioned air at desired temperature and humidity levels.
BRIEF DESCRIPTIONIn some embodiments of this disclosure, a moisture separating system comprises a first heat pump, a liquid source in thermal communication with a heat absorption section of the heat pump, and a source of a gas to be treated. The system also includes a hydrophilic nanoporous membrane comprising a first side that receives a flow of gas from the gas source and a second side that receives a flow of liquid from the liquid source.
In any of the foregoing embodiments, the first heat pump includes a heat rejection section that rejects heat to ambient air.
In any one or combination of the foregoing embodiments, the first heat pump includes a heat rejection section that rejects heat to a water flow path in communication with a cooling tower.
In any one or combination of the foregoing embodiments, the first heat pump comprises a vapor compression refrigerant heat transfer circuit that includes a refrigerant evaporator including a heat rejection side that receives a flow of liquid from the liquid source.
In any one or combination of the foregoing embodiments, the system can further comprise a heat exchanger that comprises a heat rejection side in that receives a flow of the gas, and a heat absorption side in thermal communication with the heat absorption section of the heat pump.
In any one or combination of the foregoing embodiments, the liquid source can comprise a chilled liquid circulation system that includes said first heat pump, wherein said liquid circulation system is in thermal communication with one or more heat sinks. In some embodiments, the one or more heat sinks can include the heat absorption side of the heat exchanger that comprises a heat rejection side in that receives a flow of the gas, and a heat absorption side in thermal communication with the heat absorption section of the heat pump.
In any one or combination of the foregoing embodiments, the liquid source can comprise a chilled liquid circulation system that includes said first heat pump, wherein the liquid circulation system is in thermal communication with one or more heat sinks. In some embodiments, the one or more heat sinks can include a heat exchanger comprising a heat rejection side that receives a flow of the gas, and a heat absorption side that receives a flow of liquid from the chilled liquid circulation system.
In any one or combination of the foregoing embodiments, the system can further include a second heat pump comprising a heat absorption section in thermal communication with a flow of the gas. In some embodiments, the second heat pump can be a vapor compression refrigerant heat transfer circuit, a single phase refrigerant heat transfer circuit, an electrocaloric heat pump, a thermoelastic heat pump, or a magnetocaloric heat pump. The second heat pump can comprise a second vapor compression refrigerant heat transfer circuit that includes a refrigerant evaporator in thermal communication with the flow of gas.
In some embodiments, the system can further comprise a controller configured to operate the heat exchanger or the second heat pump in a sensible heat mode in which sensible heat is absorbed from the gas by the above-referenced heat exchanger or the second heat pump, and to operate the hydrophilic nanoporous membrane in a latent heat mode in which latent heat from the condensation of water is absorbed by the liquid flowing on the second side of the membrane.
In any one or combination of the foregoing embodiments, the hydrophilic nanoporous membrane can comprise pores configured to promote capillary condensation of water vapor from the gas on the first side of the membrane and transport of condensed water to the second side of the membrane.
In any one or combination of the foregoing embodiments, the hydrophilic nanoporous membrane can comprise pores of less than or equal to 100 nm.
In any one or combination of the foregoing embodiments, the membrane can comprise an organic polymer.
In any one or combination of the foregoing embodiments, the membrane can comprise an inorganic material.
In any one or combination of the foregoing embodiments, the hydrophilic nanoporous membrane can comprise a plurality of hollow fibers.
In any one or combination of the foregoing embodiments, the hydrophilic nanoporous membrane can comprise a membrane sheet spiral wound together with a feed spacer sheet and a filtrate spacer sheet.
In any one or combination of the foregoing embodiments, the hydrophilic nanoporous membrane can comprise a plurality of membrane sheets in a stack alternately separated by a feed spacer sheet or a filtrate spacer sheet.
In any one or combination of the foregoing embodiments, the liquid can comprise water.
In any one or combination of the foregoing embodiments, the liquid can comprise a desiccant.
In some embodiments, a method of operating the gas conditioning system of any one or combination of the foregoing embodiments comprises flowing liquid from the liquid source on the first side of the hydrophilic nanoporous membrane and flowing gas from the gas source along the second side of the hydrophilic nanoporous membrane.
In some embodiments where the system can include a second heat pump or a heat exchanger comprising a heat rejection side that receives a flow of the gas, and a heat absorption side that receives a flow of liquid from a chilled liquid circulation system, the method of operating the system, the method further comprising operating the heat exchanger or the second heat pump in a sensible heat mode in which sensible heat is absorbed from the gas by the heat exchanger or the second heat pump, and operating the hydrophilic nanoporous membrane in a latent heat mode in which latent heat from the condensation of water is absorbed by the liquid flowing on the second side of the membrane.
Subject matter of this disclosure is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the present disclosure are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
It has been discovered that the energy and system component requirements on VCC systems for excess cooling to handle the latent cooling load and then reheat the air being conditioned can create inefficiency in the air conditioning process and system. Additionally, water condensation on metallic heat exchanger coils can cause corrosion problems, further adding to system design and fabrication costs as well as requiring additional system complexity. Alternate humidity removal approaches such as desiccant wheels loaded with a solid desiccant positioned downstream of a temperature control unit can be space-consuming, and significant thermal energy is typically required to regenerate the desiccant, leading to efficiency reductions. Moreover, because the desiccant wheel is relatively cumbersome and not easy to install or uninstall, the capacity and operation of the systems based on desiccant wheels are generally not modular enough to accommodate a wide range of operations. Liquid desiccant systems can avoid some of the physical configuration limitations imposed by solid desiccant systems by providing the capability to move the liquid desiccant through a flow loop. However, liquid desiccants (e.g., lithium chloride) can be highly corrosive or toxic, or both, further adding to system design complexity, system cost, and fabrication costs as well as requiring additional system maintenance. Also, as with solid desiccants, significant heat energy is typically required to regenerate the desiccant, reducing system efficiency.
With reference now to the Figures in which the same numbers may be used in different Figures to represent like components,
On the heat rejection side of the evaporator 18, the liquid from conduit 12b is cooled, rejecting heat to the refrigerant. The cooled liquid exits from the evaporator 18 and is directed through conduit 12c to the membrane unit 34. At the membrane unit 34, a fan (not numbered) can provide a source of a stream of gas to be treated 36 (e.g., air such as ambient outdoor air or any process warm humid air) is introduced to a first membrane side of the membrane unit 34. In the membrane unit 34, water vapor in the air 36 undergoes capillary condensation and is transported to the liquid circulation loop 12. For embodiments in which the liquid is water, a water removal conduit 37 (which can include vacuum backflow prevention, not shown) can provide for removal of water from the water circulation loop 12 to balance the addition of condensate from the membrane unit 34. For embodiments in which the liquid is a desiccant, techniques known for water removal desiccants can be utilized instead of the water removal conduit 37.
The liquid on the liquid circulation loop 12 can be any liquid that is compatible with the water that is condensed in and transported through the membrane. In some embodiments, the liquid compatible with water is fully soluble with water or has sufficient solubility with water to absorb the amount of condensate transported from the membrane. In some embodiments, the liquid comprises water. In some embodiments, the liquid consists of water or consists essentially of water. In some embodiments, the liquid comprises a water-soluble organic solvent. In some embodiments, the liquid comprises water and a water-soluble organic solvent. Additives such as anti-scale additives, biocides, corrosion inhibitors, pH buffers, etc., can also be included. In some embodiments, the liquid can include a desiccant. Liquid desiccants can include aqueous halide salt solutions such as a liquid desiccant lithium chloride, calcium chloride, lithium bromide, alcohol solutions (e.g. triethylene glycol, propylene glycol), or aqueous chemical agents such as CaSO4.
An example embodiment of a basic form of a membrane is schematically shown in
The hydrophilic nanoporous membrane can be formed from various materials, including organic materials (e.g., polymers) and inorganic materials. Examples of polymer membranes that can be used to form the hydrophilic nanoporous membrane include poly-piperazineamides such as the UTC-60 nanofiltration membrane supplied by Toray Corp, poly-ether-sulfones, or cellulose acetates. Additionally, polymers without inherent hydrophilicity can be rendered hydrophilic by surface treatments. For example, PVDF (poly-vinylidene fluoride)-based nanofiltration membranes including surface modification for hydrophilicity are available from Toray Corp. Examples of inorganic materials include ceramics and other inorganic materials, such as aluminum oxide (Al2O3), titanium dioxide (TiO2), nanoporous silicon or silicon dioxide (SiO2); and materials based on aluminosilicate minerals (zeolites). An example of a commercially available inorganic membrane with 10 nm pore size has a selective layer based on γ-Al2O3 and is supplied by Media & Process Technology, Inc. Composite materials or combinations of materials can also be used for membranes, e.g., polymer matrix materials with dispersed inorganic particles, multilayer membranes comprising inorganic layer(s) and polymer layer(s), or different sections of a membrane unit utilizing different types of membrane materials. Nanoporous materials typically include pores with a range or distribution of sizes, and the term “pore size” is commonly used in the membrane industry to specify a nominal single size within a distribution of pore sizes found in the actual material. Pore size, along with other parameters such as porosity, pore density or pore volume can be determined by known techniques such as gas adsorption of nitrogen using the Brunauer, Emmett and Teller (BET) technique with the membrane disposed on a gas-impermeable substrate. In some embodiments, the membranes used herein can include nanopores of less than 100 nm. In some embodiments, the membranes used herein can include nanopores of less than 50 nm. In some embodiments, the membranes used herein can include nanopores of less than 20 nm. In some embodiments, the membranes used herein can include nanopores in pore size range with a lower end of 0.5 nm, 1 nm, or 2 nm, and an upper end of 20 nm, 50 nm, or 100 nm. All possible combinations of the above-mentioned range endpoints are explicitly included herein as disclosed ranges. It should also be noted that the presence of pores outside any of the above ranges is not excluded.
Various configurations of membranes can be used for the membrane unit 34. Several example embodiments of membrane units are schematically shown in
The configuration of the air conditioning system 10a shown in
In some embodiments, the return water flow from the membrane unit 34 in
The system capability for integration of the heat exchanger such as heat exchanger 72 in thermal communication with the heat absorption section of the heat pump is facilitated by the significant heat absorbing capacity of chilled water circulation systems, but the integration can be accomplished in other systems as well. For example, a heat exchanger for cooling air could be configured into the systems of
In some embodiments, the systems disclosed herein such as the systems of
While the present disclosure has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the present disclosure is not limited to such disclosed embodiments. Rather, the present disclosure can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the present disclosure. Additionally, while various embodiments of the present disclosure have been described, it is to be understood that aspects of the present disclosure may include only some of the described embodiments. Accordingly, the present disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
Claims
1. A moisture removal system, comprising
- a first heat pump;
- a liquid source in thermal communication with a heat absorption section of the first heat pump;
- a source of gas; and
- a hydrophilic nanoporous membrane comprising a first side that receives a flow of gas from the gas source and a second side that receives a flow of liquid from the liquid source.
2. The system of claim 1, wherein the first heat pump includes a heat rejection section that rejects to heat ambient air.
3. The system of claim 1, wherein the first heat pump includes a heat rejection section that rejects heat to a water flow path in communication with a cooling tower.
4. The system of claim 1, wherein the first heat pump is a vapor compression refrigerant heat transfer circuit, a single phase refrigerant heat transfer circuit, an electrocaloric heat pump, a thermoelastic heat pump, or a magnetocaloric heat pump.
5. The system of claim 1, wherein the first heat pump comprises a vapor compression refrigerant heat transfer circuit that includes a refrigerant evaporator including a heat rejection side that receives a flow of liquid from the liquid source.
6. The system of claim 1, further comprising a heat exchanger that comprises a heat rejection side that receives a flow of the gas, and a heat absorption side in thermal communication with the heat absorption section of the first heat pump.
7. The system of claim 6, further comprising a controller configured to operate the heat exchanger in a sensible heat mode in which sensible heat is absorbed from the gas by the heat exchanger, and to operate the hydrophilic nanoporous membrane in a latent heat mode in which latent heat from the condensation of water is absorbed by the liquid flowing on the second side of the membrane.
8. The system of claim 1, wherein the liquid source comprises a chilled water circulation system that includes said first heat pump, wherein said water circulation system is in thermal communication with one or more heat sinks.
9. The system of claim 1, further including a second heat pump comprising a heat absorption section in thermal communication with a flow of the gas.
10. The system of claim 9, further comprising a controller configured to operate the second heat pump in a sensible heat mode in which sensible heat is absorbed from the gas by the second heat pump, and to operate the hydrophilic nanoporous membrane in a latent heat mode in which latent heat from the condensation of water is absorbed by the liquid flowing on the second side of the membrane.
11. The system of claim 1, wherein the hydrophilic nanoporous membrane comprises pores configured to promote capillary condensation of water vapor from the gas on the first side of the membrane and transport of condensed water to the second side of the membrane.
12. The system of claim 1, wherein the hydrophilic nanoporous membrane comprises pores of less than or equal to 100 nm.
13. The system of claim 1, wherein the hydrophilic nanoporous membrane comprises an organic polymer.
14. The system of claim 1, wherein the hydrophilic nanoporous membrane comprises a plurality of hollow fibers.
15. The system of claim 1 wherein the hydrophilic nanoporous membrane comprises a membrane sheet spiral wound together with a feed spacer sheet and a filtrate spacer sheet.
16. The system of claim 1, wherein the hydrophilic nanoporous membrane comprises a plurality of membrane sheets in a stack alternately separated by a feed spacer sheet or a filtrate spacer sheet.
17. The system of claim 1, wherein the liquid comprises water.
18. The system of claim 1, wherein the liquid comprises a desiccant.
19. A method of operating the moisture removal system of claim 1, comprising flowing from the liquid source on the first side of the hydrophilic nanoporous membrane and flowing gas from the gas source along the second side of the hydrophilic nanoporous membrane.
20. The method of claim 19, wherein the system further comprises a heat exchanger that comprises a heat rejection side that receives a flow of the gas, and a heat absorption side in thermal communication with the heat absorption section of the first heat pump, or the system further comprises a second heat pump comprising a heat absorption section in thermal communication with a flow of the gas, and wherein the method further comprises operating the heat exchanger or the second heat pump in a sensible heat mode in which sensible heat is absorbed from the gas by the heat exchanger or the second heat pump, and operating the hydrophilic nanoporous membrane in a latent heat mode in which latent heat from the condensation of water is absorbed by the liquid flowing on the second side of the membrane.
Type: Application
Filed: Jan 19, 2018
Publication Date: Jul 26, 2018
Inventors: Yinshan Feng (South Windsor, CT), Parmesh Verma (South Windsor, CT), Haralambos Cordatos (Colchester, CT)
Application Number: 15/875,693