Liquid desiccant air conditioning using air as the heat transfer medium

Abstract

The liquid desiccant system includes a liquid desiccant loop having an adsorber in fluid communication with a desorber and liquid desiccant flowing between the adsorber and the desorber. The liquid desiccant system includes a supply airflow path passing through the adsorber and forming an adsorption liquid / air interface in the adsorber and a conditioned airflow exiting the adsorber. The liquid desiccant system includes a regeneration airflow path passing through the desorber and forming a desorption liquid / air interface in the desorber and an exhaust airflow exiting the desorber. A heat exchanger is thermally coupled to the supply airflow path for removing heat from the supply airflow upstream of the adsorber. A heat exchanger is thermally coupled to the regeneration airflow path for adding heat to the regeneration airflow upstream of the desorber.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. patent application Ser. No. 17,719,598, filed April 13, 2022, and entitled “Liquid Desiccant Air Conditioning Using Air as a Heat Transfer Medium,” which is hereby incorporated by reference in its entirety. Summary of the Invention

[0002] The present disclosure relates generally to air dehumidification systems that utilize liquid desiccant.

[0003] The present disclosure is directed to liquid desiccant systems in which heat and mass transfer occurs only at the liquid / air interface in the desorber and adsorber. The liquid desiccant systems may not include a desiccant-liquid (such as water or refrigerant) heat exchanger, thus reducing the complexity and cost of the liquid desiccant system while enabling a highly efficient air dehumidification system.

[0004] The present disclosure is directed to a liquid desiccant system including a liquid desiccant loop having an adsorber in fluid communication with a desorber and liquid desiccant flowing between the adsorber and the desorber. The liquid desiccant system includes a feed airflow path passing through the adsorber and forming an adsorption liquid / air interface in the adsorber and a conditioned airflow exiting the adsorber. The liquid desiccant system includes a regeneration airflow path passing through the desorber and forming a desorption liquid / air interface in the desorber and a exhaust airflow exiting the desorber. A heat exchanger is thermally coupled to the feed airflow path for removing heat from the feed airflow upstream of the adsorber. A heat exchanger is thermally coupled to the regeneration airflow path and adds heat to the regeneration airflow upstream of the desorber. At least 95%, or at least 99%, of the total heat added to the liquid desiccant may be added at the desorption liquid / air interface.

[0005] The present disclosure is directed to a liquid desiccant system including a liquid desiccant loop having an adsorber in fluid communication with a desorber and liquid desiccant flowing between the adsorber and the desorber. The liquid desiccant system includes a feed airflow path passing through the adsorber and forming an adsorption liquid / air interface in the adsorber and a conditioned airflow exiting the adsorber. The liquid desiccant system includes a regeneration airflow path passing through the desorber and forming a desorption liquid / air interface in the desorber and a exhaust airflow exiting the desorber. A heat exchanger is thermally coupled to the feed airflow path for removing heat from the feed airflow upstream of the adsorber. The heat exchanger is also thermally coupled to the regeneration airflow path for adding heat to the regeneration airflow upstream of the desorber. At least 95%, or at least 99%, of the total heat added to the liquid desiccant may be added at the desorption liquid / air interface.

[0006] The present disclosure is directed to a method of conditioning an airflow, including circulating a liquid desiccant through a liquid desiccant loop including an adsorber and liquid desiccant in fluid communication with a desorber, flowing a feed air along a feed airflow path and through the adsorber to form an adsorption liquid / air interface in the adsorber and a conditioned airflow exiting the adsorber, and flowing a regeneration air along a regeneration airflow path and through the desorber to form a desorption liquid / air interface in the desorber and a conditioned airflow exiting the desorber. The method includes removing heat from the feed air upstream of the adsorber and adding heat to the regeneration airflow upstream of the desorber. The liquid desiccant has a first temperature exiting the desorber and a second temperature entering the adsorber, the first temperature and the second temperature being within 5% of each other, or within 1% of each other, or equal. At least 95%, or at least 99%, of the total heat added to the liquid desiccant may be added at the desorption liquid / air interface.

[0007] The present disclosure is directed to a method of conditioning an airflow, comprising: circulating a liquid desiccant through a liquid desiccant loop comprising an adsorber and liquid desiccant in fluid communication with a desorber; flowing a feed air along a feed airflow path and through the adsorber to form an adsorption liquid / air interface in the adsorber and a conditioned airflow exiting the adsorber; and flowing a regeneration air along a regeneration airflow path and through the desorber to form a desorption liquid / air interface in the desorber and an exhaust airflow exiting the desorber. The method comprises removing heat from the feed air upstream of the adsorber and adding the heat to the regeneration airflow upstream of the desorber. The liquid desiccant has a first temperature exiting the desorber and a second temperature entering the adsorber, the first temperature and the second temperature being within 5% of each other, or within 1% of each other, or being equal. At least 95%, or at least 99%, of the total heat added to the liquid desiccant may be added at the desorption liquid / air interface.

[0008] The present disclosure is directed to a liquid desiccant system including a liquid desiccant loop having an adsorber in fluid communication with a desorber and liquid desiccant flowing between the adsorber and the desorber. The liquid desiccant system includes a feed airflow path passing through the adsorber and forming an adsorption liquid / air interface in the adsorber and a conditioned airflow exiting the adsorber. The liquid desiccant system includes a regeneration airflow path passing through the desorber and forming a desorption liquid / air interface in the desorber and a exhaust airflow exiting the desorber. A heat exchanger is thermally coupled to the feed airflow path for removing heat from the feed airflow upstream of the adsorber. The heat exchanger is also thermally coupled to the regeneration airflow path for adding heat to the regeneration airflow upstream of the desorber. The liquid desiccant loop does not include a refrigerant-to-liquid heat exchanger or a water-to-liquid desiccant heat exchanger.

[0009] The present disclosure is directed to a method of conditioning an airflow including circulating a liquid desiccant through a liquid desiccant loop including an adsorber and liquid desiccant in fluid communication with a desorber, flowing a feed air along a feed airflow path and through the adsorber to form an adsorbed liquid / air interface in the adsorber and a conditioned airflow exiting the adsorber, and flowing a regeneration air along a regeneration airflow path and through the desorber to form a desorption liquid / air interface in the desorber and a conditioned airflow exiting the desorber. The method includes removing heat from the feed air upstream of the adsorber and adding heat to the regeneration airflow upstream of the desorber. The liquid desiccant loop does not include a refrigerant-to-liquid heat exchanger or a water-to-liquid desiccant heat exchanger.

[0010] The following discussion refers to the following figures, in which the same reference numbers may be used to identify similar / identical components in the various figures, and in which the figures are not necessarily drawn to scale: [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram of an exemplary liquid desiccant system. [Diagram 2] FIG. 2 is a schematic diagram of another exemplary liquid desiccant system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present disclosure relates generally to heating, ventilation, and air conditioning (HVAC) systems. In one exemplary embodiment, a gas-to-liquid vapor exchanger includes an adsorber and a desorber to regenerate liquid desiccant that passes through both the adsorber and the desorber. These units can be used to adsorb and desorb water vapor into and out of the liquid desiccant to dehumidify or humidify air. This humidification and dehumidification can be used in HVAC heating and cooling applications.

[0013] Air conditioning systems may perform two functions simultaneously: first dehumidifying and then cooling the forced airflow. Commonly used air conditioning systems use vapor compression, which can dehumidify and cool the incoming air. However, when considering a high humidity airflow, vapor compression may rely on cooling the airflow below its supply temperature to condense the moisture to achieve a low absolute humidity, and then reheating the air to its supply temperature. This moisture condensation process dramatically increases the energy requirements of the air conditioner, especially in humid climates. An alternative dehumidification method, known as liquid desiccant dehumidification, can substantially reduce the energy intensity of air conditioning and is the subject of this disclosure.

[0014] The use of liquid desiccants to remove moisture from air is an energy-efficient alternative to vapor compression because it minimizes or eliminates the need to cool and reheat the airstream. In a liquid desiccant dehumidification system, humid air exchanges water vapor with a liquid desiccant. A gas-liquid vapor exchanger (adsorber) may be used to contact the humid air with the liquid desiccant and transfer water vapor in the humid air into the liquid desiccant to form a humidified liquid desiccant. This humidified liquid desiccant may be regenerated in a gas-liquid vapor exchanger (desorber) by heating the humidified liquid desiccant to expel the water vapor and return the regenerated liquid desiccant to the adsorber.

[0015] The present disclosure is directed to liquid desiccant systems in which heat and mass transfer occurs only at the liquid / air interface in the desorber and adsorber. Heat is added to or removed from the liquid desiccant only at the liquid / air interface in the desorber and adsorber. The liquid desiccant system may not include a desiccant-liquid (such as water or refrigerant) heat exchanger, thus reducing the complexity and cost of the liquid desiccant system while enabling a highly efficient air dehumidification system.

[0016] Current liquid desiccant air conditioning systems utilize liquid desiccant cooling and heating using heat exchangers. These heat exchangers are typically counter-flow operable, providing a heating or cooling liquid flowing in a first direction and liquid desiccant flowing in the opposite direction, transferring heat via thermal conduction through the heat exchanger conduit walls. These heat exchangers are formed of specialized materials to handle the corrosive liquid desiccant and are therefore expensive and complex.

[0017] The present disclosure provides a highly efficient liquid desiccant air conditioning system while eliminating these desiccant-liquid heat exchangers. The present disclosure provides a simplified liquid desiccant air conditioning system that can be easily retrofitted onto conventional air conditioning systems. The present disclosure describes a highly efficient liquid desiccant air conditioning system that utilizes standard air coils to heat and cool the air entering the adsorber and desorber. The air passing through the adsorber and desorber provides the heating and cooling of the liquid desiccant. This simplifies the system architecture, eliminates expensive components, and paves the way for retrofitting existing conventional air conditioners with liquid desiccant.

[0018] FIG. 1 is a schematic diagram of an exemplary liquid desiccant system 100. FIG. 2 is a schematic diagram of another exemplary liquid desiccant system 100. The liquid desiccant system 100 of FIG. 2 illustrates that heat removed from the adsorption operation 101 is added to the desorption operation 102. The liquid desiccant system 100 of FIG. 1 illustrates that heat is removed from the adsorption operation 101 via a heat sink 145 and heat is added to the desorption operation 102 via a heat source 155. The heat sink 145 may be any useful heat sink unit operating to remove heat from the adsorption operation 101, such as a refrigerant-air condenser coil, chilled water coil, evaporative cooler, and the like. The heat source 155 may be any useful heat source unit operating to provide heat to the desorption operation 102, such as electric heat, gas-fired heat, solar heat, geothermal heat, condenser coil, and the like.

[0019] The liquid desiccant system 100 includes a liquid desiccant loop 110 having an adsorber 112 in fluid communication with a desorber 114 and liquid desiccant flowing between the adsorber 112 and the desorber 114 .

[0020] The liquid desiccant system 100 includes a supply airflow path 120 that passes through the adsorber 112 and forms an adsorbed liquid / air interface within the adsorber 112, and a conditioned airflow 122 that exits the adsorber 112. The liquid desiccant system 100 includes a regeneration airflow path 130 that passes through the desorber 114 and forms a desorbed liquid / air interface within the desorber 114, and an exhaust airflow 132 that exits the desorber 114.

[0021] The heat exchanger 140 is thermally coupled to the feed airflow path 120 for removing heat from the feed airflow 120 upstream of the adsorber 112. The heat exchanger 150 is thermally coupled to the regeneration airflow path 130 for adding heat to the regeneration airflow 130 upstream of the desorber 114.

[0022] The liquid desiccant has a first temperature exiting the adsorber 112 and a second temperature entering the desorber 114, the first and second temperatures being within 5% of each other, or within 1% of each other, or equal. At least 95%, or at least 99%, of the total heat added to the liquid desiccant may be added at the desorption liquid / air interface.

[0023] The liquid desiccant has a first temperature exiting the desorber 114 and a second temperature entering the adsorber 112, the first and second temperatures being within 5% of each other, or within 1% of each other, or equal. At least 95%, or at least 99%, of the total heat removed to the liquid desiccant may be removed at the adsorbent liquid / air interface.

[0024] In the adsorption operation 101, the heat exchanger 140 may include an evaporator coil in the supply airflow path 120 configured to remove heat from the supply airflow. The cooled supply airflow 121 then enters the adsorber 112 to both cool (remove heat from) the liquid desiccant and transfer humidity from the cooled supply airflow to the liquid desiccant at the adsorbent liquid / air interface.

[0025] The adsorbent liquid / air interface may be formed by any vapor / liquid mass transfer unit operation. Exemplary vapor / liquid mass transfer unit operations include, for example, packed beds, tray towers, spray towers, bubble columns, membranes, and the like.

[0026] Both heat and mass transfer occur only at the liquid / air interface within the adsorber 112 for the adsorption operation 101. No heat is removed from the liquid desiccant outside the adsorber 112.

[0027] In the desorption operation 102, the heat exchanger 150 may include a condenser coil in the regeneration airflow path 130 configured to add heat to the regeneration airflow. The heated regeneration airflow 131 then enters the desorber 114, heating the liquid desiccant and transferring moisture from the liquid desiccant at the desorption liquid / air interface to the heated regeneration airflow.

[0028] The desorption liquid / air interface may be formed by any vapor / liquid mass transfer unit operation. Exemplary vapor / liquid mass transfer unit operations include, for example, packed beds, tray towers, spray towers, bubble columns, membranes, and the like.

[0029] Both heat and mass transfer occur only at the liquid / air interface within the desorber 114 for the desorption operation 102. No heat is added from the liquid desiccant outside the desorber 114.

[0030] The system or liquid desiccant loop 110 does not include a refrigerant-to-liquid heat exchanger or a water-to-liquid desiccant heat exchanger. The liquid desiccant loop is a closed loop that does not include any heat exchange operations other than the heat exchange at the liquid / air interfaces in the adsorber 112 and desorber 114. No heat is added or removed from the liquid desiccant outside of the adsorber 112 or desorber 114. The liquid desiccant loop 110 includes one or more liquid pumps, which are assumed not to add significant heat to the liquid desiccant through the pumping action of the liquid pump.

[0031] The liquid desiccant loop 110 may include an adsorption recycle loop 113. The adsorption recycle loop 113 removes liquid desiccant from the adsorber 112 and delivers the liquid desiccant back into the adsorber 112. The liquid desiccant loop 110 includes transfer piping 115 for fluidly connecting the liquid desiccant from the adsorber 112 to the desorber 114. The liquid desiccant loop 110 includes transfer piping 116 for fluidly connecting the liquid desiccant from the desorber 114 to the adsorber 112.

[0032] 1 and 2 illustrate the desorber 114 having a single pass of liquid desiccant through the desorber 114. The mass flow rate of liquid desiccant through the desorber 114 is substantially equal to the mass flow rate of liquid desiccant entering the desorber 114 from the adsorber 112 via transfer line 115. The mass flow rate of liquid desiccant through the desorber 114 is substantially equal to the mass flow rate of liquid desiccant leaving the desorber 114 via transfer line 116 to the adsorber 112.

[0033] Alternatively, liquid desiccant loop 110 may include a desorption recycle loop (not shown) that removes liquid desiccant from desorber 114 and pumps liquid desiccant back into desorber 114. In these embodiments, the mass flow rate of liquid desiccant through desorber 114 is greater than either the mass flow rate of liquid desiccant entering desorber 114 from adsorber 112 via transfer line 115 or the mass flow rate of liquid desiccant leaving desorber 114 via transfer line 116 to adsorber 112.

[0034] The liquid desiccant has a first temperature exiting the adsorber 112 and a second temperature entering the desorber 114 via line 115. The first and second temperatures are within 5% of each other, or within 1% of each other, or are equal. No heat is added to the liquid desiccant along line 115 from the adsorber 112 to the desorber 114. No heat is removed from the liquid desiccant along line 115 from the adsorber 112 to the desorber 114. No heat is added or removed along the recycle line 113 other than a small amount added by the fluid pump via the pump.

[0035] The liquid desiccant has a first temperature exiting the desorber 114 and a second temperature entering the adsorber 112 via line 116. The first and second temperatures are within 5% of each other, or within 1% of each other, or are equal. No heat is added to the liquid desiccant along line 116 from the desorber 114 to the adsorber 112. No heat is removed from the liquid desiccant along line 116 from the desorber 114 to the adsorber 112. No heat is added to any desorber 114 recycle lines (if present) other than a small amount added by the fluid pump via the pump.

[0036] The regeneration airflows 130, 131 into the desorber 114 have a regeneration mass airflow velocity value, and the liquid desiccant flowing through the desorber 114 has a desorption liquid desiccant mass flow rate value. The regeneration mass airflow velocity value is within a range of 40-80 times the desorption liquid desiccant mass flow rate value. The regeneration mass airflow velocity value is within a range of 50-70 times the desorption liquid desiccant mass flow rate value. The regeneration mass airflow velocity value is within a range of 55-65 times the desorption liquid desiccant mass flow rate value.

[0037] The feed airflows 120, 121 into the adsorber 112 have a feed mass airflow velocity value, and the liquid desiccant flowing through the adsorber 112 has a sorbed liquid desiccant mass flow rate value. The feed mass airflow velocity value is in the range of 1 to 10 times the sorbed liquid desiccant mass flow rate value. The feed mass airflow velocity value is in the range of 1 to 10 times the sorbed liquid desiccant mass flow rate value. The feed mass airflow velocity value is in the range of 1 to 5 times the sorbed liquid desiccant mass flow rate value. The feed mass airflow velocity value is in the range of 1 to 3 times the sorbed liquid desiccant mass flow rate value.

[0038] Liquid desiccant may flow through the adsorber 112 at a sorption liquid desiccant mass flow rate value, and liquid desiccant may flow through the desorber 114 at a desorption liquid desiccant mass flow rate value. The desorption liquid desiccant mass flow rate value is between 0.5% and 5% of the sorption liquid desiccant mass flow rate value. The desorption liquid desiccant mass flow rate value is between 0.5% and 4% of the sorption liquid desiccant mass flow rate value. The desorption liquid desiccant mass flow rate value is between 1% and 3% of the sorption liquid desiccant mass flow rate value.

[0039] The liquid desiccant may be a halide salt solution. The halide salt may be selected from sodium chloride (NaCl), potassium chloride (KCl), potassium iodide (KI), lithium chloride (LiCl), copper (II) chloride (CuCl2), silver chloride (AgCl), calcium chloride (CaCl2), chlorine fluoride (ClF), bromomethane (CH3Br), iodoform (CHI3), hydrogen chloride (HCl), lithium bromide (LiBr), hydrogen bromide (HBr), and combinations thereof. In some embodiments, the halide salt solution is selected from LiCl, NaCl, LiBr, and CaCl2. In some embodiments, the halide salt solution is LiCl. The solution may be water and may be described as an aqueous solution. The halide salt may be present in the liquid desiccant in a range of 2-50% by weight, or in a range of 10-40% by weight, or in a range of 20-40% by weight.

[0040] The liquid desiccant concentration value in the desorber 114 is greater than the liquid desiccant concentration value in the adsorber 112. The liquid desiccant concentration value in the desorber 114 may be 3% or more by weight greater than the liquid desiccant concentration value in the adsorber 112. The liquid desiccant concentration value in the desorber 114 may be 4% or more by weight greater than the liquid desiccant concentration value in the adsorber 112. The liquid desiccant concentration value in the desorber 114 may be 5% or more by weight greater than the liquid desiccant concentration value in the adsorber 112. The liquid desiccant concentration value in the desorber 114 may be 6% or more by weight greater than the liquid desiccant concentration value in the adsorber 112. The liquid desiccant concentration value in the desorber 114 may be 7% or more by weight greater than the liquid desiccant concentration value in the adsorber 112. The liquid desiccant concentration value in the desorber 114 may be 8% or more by weight greater than the liquid desiccant concentration value in the adsorber 112.

[0041] The concentration value of the liquid desiccant in the desorber 114 may be within a range of 3% by weight to 15% by weight higher than the concentration value of the liquid desiccant in the adsorber 112. The concentration value of the liquid desiccant in the desorber 114 may be within a range of 3% by weight to 10% by weight higher than the concentration value of the liquid desiccant in the adsorber 112. The concentration value of the liquid desiccant in the desorber 114 may be within a range of 5% by weight to 15% by weight higher than the concentration value of the liquid desiccant in the adsorber 112. The concentration value of the liquid desiccant in the desorber 114 may be within a range of 5% by weight to 10% by weight higher than the concentration value of the liquid desiccant in the adsorber 112.

[0042] The liquid desiccant system 100 of Figure 2 illustrates that heat removed from the adsorption operation 101 is added to the desorption operation 102. The vapor compressor 157 transfers refrigerant and heat from the supply air stream 120 to the regeneration air stream 130. The heat removed from the supply air stream 120 is added to the regeneration air stream 130. Additional heat from the vapor compressor 157 may also be added to the regeneration air stream 130.

[0043] In some embodiments, a portion of the heat removed from the supply air stream 120 is dissipated in the condenser unit 152 not along the regenerative air stream path 130. In other embodiments, a portion of the regenerative air stream is removed from the regenerative air stream path between the heat exchanger 150 and the desorber 114.

[0044] The method of conditioning the airflow includes circulating liquid desiccant through a liquid desiccant loop 110 including an adsorber 112 in fluid communication with a desorber 114. The method includes flowing feed air along a feed airflow path 120 and through the adsorber 112 to form an adsorbed liquid / air interface within the adsorber 112 and a conditioned airflow 122 exiting the adsorber 112. The method includes flowing regeneration air along a regeneration airflow path 130 and through the desorber 114 to form a desorbed liquid / air interface within the desorber 114 and an exhaust airflow 132 exiting the desorber 114. The method includes removing heat from the feed air 120 upstream of the adsorber 112 and adding heat to the regeneration airflow 130 upstream of the desorber 114. The liquid desiccant has a first temperature exiting the desorber 114 and a second temperature entering the adsorber 112, the first temperature and the second temperature being within 5% of each other, or within 1% of each other, or equal. At least 95%, or at least 99%, of the total heat added to the liquid desiccant may be added at the liquid / air interface of the desorber 114.

[0045] The method includes flowing regeneration air 130 through the desorber 114 at a regeneration mass air velocity value and flowing liquid desiccant through the desorber 114 at a desorption liquid desiccant mass flow rate value. The regeneration mass air velocity value is within a range of 40-80 times the desorption liquid desiccant mass flow rate value. The regeneration mass air velocity value is within a range of 50-70 times the desorption liquid desiccant mass flow rate value. The regeneration mass air velocity value is within a range of 55-65 times the desorption liquid desiccant mass flow rate value.

[0046] The method may include flowing supply air 120 through the adsorber 112 at a supply mass air velocity value and flowing liquid desiccant through the adsorber 112 at a sorbent liquid desiccant mass flow rate value. The supply mass air velocity value is in a range of 1 to 10 times the sorbent liquid desiccant mass flow rate value. The supply mass air velocity value is in a range of 1 to 5 times the sorbent liquid desiccant mass flow rate value. The supply mass air velocity value is in a range of 1 to 3 times the sorbent liquid desiccant mass flow rate value.

[0047] The method may include flowing the liquid desiccant through the adsorber 112 at a first mass flow rate and flowing the liquid desiccant from the adsorber 112 to the desorber 114 at a second mass flow rate. The second mass flow rate is between 0.5% and 5% of the first mass flow rate. The second mass flow rate is between 0.5% and 4% of the first mass flow rate. The second mass flow rate is between 1% and 3% of the first mass flow rate.

[0048] Removing heat may include flowing the supply air through an evaporator coil 140 in the supply airflow path 120. Adding heat may include flowing the regeneration air through a condenser coil 150 in the regeneration airflow path 130. The method does not include a refrigerant-to-liquid desiccant heat exchanger or a water-to-liquid desiccant heat exchanger. EXAMPLES

[0049] In one embodiment, the feed air stream has a temperature of 70° F, an absolute humidity of 0.0128 kg H2O / kg air, and a flow rate of 1000 CFM. The evaporator coil removes heat from the feed air stream to form a cooled feed air stream having a temperature of 60° F, a relative humidity of 77.3, and a flow rate of 1000 CFM entering the adsorber. The liquid desiccant that recirculates within and leaves the adsorber has a temperature of 70° F, a flow rate to the desorber of 0.25 liters / minute, and a recirculation flow rate of 12 liters / minute. The liquid desiccant is an aqueous solution that contains about 25% by weight of desiccant (LiCl) during adsorber operation. The conditioned air stream leaving the adsorber has a temperature of 70° F, an absolute humidity of 0.0091 kg H2O / kg air, and a flow rate of 1000 CFM. The ratio of adsorption air mass flow rate to adsorption liquid desiccant mass flow rate is about 2.5:1.

[0050] In this embodiment, the regeneration air stream has a temperature of 70° F, an absolute humidity of 0.0128 kg H2O / kg of air, and a flow rate of 550 CFM. The condenser coil adds heat to the regeneration air stream to form a heated regeneration air stream having a temperature of 100° F, an absolute humidity of 0.0127 kg H2O / kg of air, and a flow rate of 550 CFM entering the desorber. The liquid desiccant circulates through and exits the desorber has a temperature of 98° F and a flow rate of 0.19 liters / minute. The liquid desiccant is an aqueous solution containing about 32% by weight of desiccant (LiCl) in the desorber operation. The exhaust air stream exiting the desorber has a temperature of 83° F, an absolute humidity of 113, and a flow rate of 550 CFM. The ratio of desorption air mass flow rate to desorption liquid desiccant mass flow rate is approximately 61:1.

[0051] In this system, heat is added to the liquid desiccant only at the liquid / air interface in the desorber.In this system, heat is removed to the liquid desiccant only at the liquid / air interface in the adsorber.

[0052] This example demonstrated a surprisingly high moisture removal efficiency (MRE) of approximately 4 kg / kWh. MRE is the moisture removal rate (mass / time) divided by the power input to the air conditioning or liquid desiccant system.

[0053] Unless otherwise indicated, all numbers expressing size, quantity, and physical properties of features used in the specification and claims should be understood in all cases as modified by the term "about". Thus, unless otherwise indicated, the numerical parameters set forth in the foregoing specification and appended claims are approximations that can vary depending on the desired properties sought to be obtained by those of ordinary skill in the art utilizing the teachings disclosed herein. The use of numerical ranges by endpoints includes all numbers within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5), and any range within that range.

[0054] The foregoing description has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the embodiments to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. Any or all features of the disclosed embodiments may be applied individually or in any combination and are not intended to be limiting, but merely exemplary. It is intended that the scope of the invention be determined not by this detailed description, but rather by the claims appended hereto.

Claims

1. 1. A liquid desiccant system comprising: a liquid desiccant loop comprising an adsorber in fluid communication with a desorber and liquid desiccant flowing between the adsorber and the desorber; a feed airflow path passing through the adsorber and forming an adsorbed liquid / air interface within the adsorber and a conditioned airflow exiting the adsorber; a regeneration airflow path passing through the desorber and forming a desorption liquid / air interface within the desorber and an exhaust airflow exiting the desorber; a heat exchanger thermally coupled to the supply airflow path and for removing heat from the supply airflow upstream of the adsorber, and a heat exchanger thermally coupled to the regeneration airflow path and for adding heat to the regeneration airflow upstream of the desorber; A liquid desiccant system, wherein at least 95% of the total heat added to the liquid desiccant is added at the desorption liquid / air interface in the desorber.

2. 10. The liquid desiccant system of claim 1, wherein at least 99% of the total heat added to the liquid desiccant is added at the desorption liquid / air interface in the desorber.

3. 2. The liquid desiccant system of claim 1, wherein the liquid desiccant has a first temperature exiting the adsorber and a second temperature entering the desorber, the first temperature and the second temperature being substantially equal.

4. 2. The liquid desiccant system of claim 1, wherein the heat exchanger comprises an evaporator coil in the supply airflow path configured to remove heat from the supply airflow.

5. 10. The liquid desiccant system of claim 1, wherein the heat exchanger comprises a condenser coil in the regeneration airflow path configured to add heat from the regeneration airflow.

6. 10. The liquid desiccant system of claim 1, wherein the liquid desiccant loop does not include a refrigerant-to-liquid heat exchanger or a water-to-liquid desiccant heat exchanger.

7. 2. The liquid desiccant system of claim 1, wherein the heat removed from the supply air stream is added to the regeneration air stream.

8. 8. The liquid desiccant system of claim 7, wherein a portion of the heat removed from the supply airflow is dissipated in a condenser unit that is not along the regenerative airflow path.

9. 8. The liquid desiccant system of claim 7, wherein a portion of the regeneration airflow is removed from the regeneration airflow path between the heat exchanger and the desorber.

10. 2. The liquid desiccant system of claim 1, wherein the regeneration airflow into the desorber has a regeneration mass airflow velocity value and the liquid desiccant flowing through the desorber has a desorption liquid desiccant mass flow rate value, the regeneration mass airflow velocity value being within a range of 40 to 80 times the desorption liquid desiccant mass flow rate value.

11. 11. The liquid desiccant system of claim 10, wherein the feed airflow into the adsorber has a feed mass air velocity value and the liquid desiccant flowing through the adsorber has a sorbent liquid desiccant mass flow rate value, the feed mass air velocity value being within a range of 1 to 10 times the sorbent liquid desiccant mass flow rate value.

12. 11. The liquid desiccant system of claim 10, wherein liquid desiccant flows through the adsorber at an adsorption liquid desiccant mass flow value, and liquid desiccant flows through the desorber at a desorption liquid desiccant mass flow value, the desorption liquid desiccant mass flow value being between 0.5% and 5% of the adsorption liquid desiccant mass flow value, and the desorption liquid desiccant mass flow value through the desorber being substantially equal to a liquid desiccant mass flow value from the adsorber to the desorber.

13. The liquid desiccant is LiCl, NaCl, LiBr, or CaCl ２ 10. The liquid desiccant system of claim 1 comprising:

14. 10. The liquid desiccant system of claim 1, wherein the liquid desiccant comprises LiCl.

15. 11. The liquid desiccant system of claim 10, wherein liquid desiccant flows through the adsorber at an adsorption liquid desiccant mass flow value, and liquid desiccant flows through the desorber at a desorption liquid desiccant mass flow value, the desorption liquid desiccant mass flow value being between 0.5% and 5% of the adsorption liquid desiccant mass flow value, and the desorption liquid desiccant mass flow value through the desorber being greater than the liquid desiccant mass flow value from the adsorber to the desorber.

16. 2. The liquid desiccant system of claim 1, wherein a concentration value of the liquid desiccant in the desorber is at least 3% by weight greater than a concentration value of the liquid desiccant in the adsorber.

17. 2. The liquid desiccant system of claim 1, wherein a concentration value of the liquid desiccant in the desorber is at least 5% by weight greater than a concentration value of the liquid desiccant in the adsorber.

18. 1. A method for adjusting airflow, comprising: circulating the liquid desiccant through a liquid desiccant loop comprising an adsorber and liquid desiccant in fluid communication with a desorber; flowing feed air along a feed airflow path and through said adsorber to form an adsorbed liquid / air interface within said adsorber and a conditioned airflow exiting said adsorber; flowing regeneration air along a regeneration airflow path and through the desorber to form a desorption liquid / air interface within the desorber and an exhaust airflow exiting the desorber; removing heat from the supply air upstream of the adsorber; adding heat to the regeneration air upstream of the desorber; The method, wherein the liquid desiccant has a first temperature exiting the desorber and a second temperature entering the adsorber, the first temperature and the second temperature being substantially equal.

19. 20. The method of claim 18, further comprising flowing regeneration air through the desorber at a regeneration mass air velocity value and flowing liquid desiccant through the desorber at a desorption liquid desiccant mass flow rate value, wherein the regeneration mass air velocity value is within a range of 40 to 80 times the desorption liquid desiccant mass flow rate value.

20. 20. The method of claim 19, further comprising flowing feed air through said adsorber at a feed mass air velocity value and flowing liquid desiccant through said adsorber at a sorbent liquid desiccant mass flow rate value, said feed mass air velocity value being within the range of 1 to 10 times said sorbent liquid desiccant mass flow rate value.

21. 20. The method of claim 19, further comprising flowing liquid desiccant through the adsorber at a first mass flow rate and flowing liquid desiccant from the adsorber to the desorber at a second mass flow rate, the second mass flow rate being between 0.5% and 5% of the first mass flow rate.

22. 20. The method of claim 18, wherein removing heat comprises flowing supply air through an evaporator coil in the supply airflow path, and adding heat comprises flowing regeneration air through a condenser coil in the regeneration airflow path.

23. The method of claim 18, wherein the method does not include a refrigerant-to-liquid desiccant heat exchanger or a water-to-liquid desiccant heat exchanger.

24. 20. The method of claim 18, wherein at least 95% of the total heat added to the liquid desiccant is added at the desorption liquid / air interface in the desorber.

25. 20. The method of claim 18, wherein at least 99% of the total heat added to the liquid desiccant is added at the desorption liquid / air interface in the desorber.

26. 1. A liquid desiccant system comprising: a liquid desiccant loop comprising an adsorber in fluid communication with a desorber and liquid desiccant flowing between the adsorber and the desorber; a feed airflow path passing through the adsorber and forming an adsorbed liquid / air interface within the adsorber and a conditioned airflow exiting the adsorber; a regeneration airflow path passing through the desorber and forming a desorption liquid / air interface within the desorber and an exhaust airflow exiting the desorber; a heat exchanger thermally coupled to the supply airflow path and for removing heat from the supply airflow upstream of the adsorber, and a heat exchanger thermally coupled to the regeneration airflow path and for adding heat to the regeneration airflow upstream of the desorber; A liquid desiccant system, wherein the liquid desiccant loop does not include a refrigerant-to-liquid heat exchanger or a water-to-liquid desiccant heat exchanger.

27. 27. The liquid desiccant system of claim 26, wherein at least 99% of the total heat added to the liquid desiccant is added at the desorption liquid / air interface in the desorber.

28. 28. The liquid desiccant system of claim 27, wherein the liquid desiccant has a first temperature exiting the adsorber and a second temperature entering the desorber, the first temperature and the second temperature being substantially equal.

29. 27. The liquid desiccant system of claim 26, wherein the heat exchanger comprises an evaporator coil in the supply airflow path configured to remove heat from the supply airflow, and the heat exchanger comprises a condenser coil in the regeneration airflow path configured to add heat to the regeneration airflow, the heat removed from the supply airflow being added to the regeneration airflow.

30. 30. The liquid desiccant system of claim 29, wherein a portion of the heat removed from the supply airflow is dissipated in a condenser unit that is not along the regenerative airflow path.

31. 27. The liquid desiccant system of claim 26, wherein the regeneration airflow into the desorber has a regeneration mass airflow velocity value and the liquid desiccant flowing through the desorber has a desorption liquid desiccant mass flow rate value, the regeneration mass airflow velocity value being within a range of 40 to 80 times the desorption liquid desiccant mass flow rate value.

32. 27. The liquid desiccant system of claim 26, wherein a concentration value of the liquid desiccant in the desorber is at least 3% by weight greater than a concentration value of the liquid desiccant in the adsorber.

33. 27. The liquid desiccant system of claim 26, wherein a concentration value of the liquid desiccant in the desorber is at least 5% by weight greater than a concentration value of the liquid desiccant in the adsorber.

34. 1. A method for adjusting airflow, comprising: circulating the liquid desiccant through a liquid desiccant loop comprising an adsorber and liquid desiccant in fluid communication with a desorber; flowing feed air along a feed airflow path and through said adsorber to form an adsorbed liquid / air interface within said adsorber and a conditioned airflow exiting said adsorber; flowing regeneration air along a regeneration airflow path and through the desorber to form a desorption liquid / air interface within the desorber and an exhaust airflow exiting the desorber; removing heat from the supply air upstream of the adsorber; adding heat to the regeneration air upstream of the desorber; The method, wherein the liquid desiccant loop does not include a refrigerant-to-liquid heat exchanger or a water-to-liquid desiccant heat exchanger.

35. 35. The method of claim 34, wherein at least 99% of the total heat added to the liquid desiccant is added at the desorption liquid / air interface in the desorber.

36. 35. The method of claim 34, wherein the liquid desiccant has a first temperature exiting the adsorber and a second temperature entering the desorber, the first temperature and the second temperature being substantially equal.

37. 35. The method of claim 34, wherein the heat removed from the supply air is added to the regeneration air.

38. 35. The method of claim 34, wherein the regeneration airflow into the desorber has a regeneration mass airflow velocity value and the liquid desiccant flowing through the desorber has a desorption liquid desiccant mass flow rate value, the regeneration mass airflow velocity value being within a range of 40 to 80 times the desorption liquid desiccant mass flow rate value.

39. 35. The method of claim 34, wherein the concentration value of the liquid desiccant in the desorber is at least 3 wt. % greater than the concentration value of the liquid desiccant in the adsorber.

40. 35. The method of claim 34, wherein the concentration value of the liquid desiccant in the desorber is at least 5% by weight greater than the concentration value of the liquid desiccant in the adsorber.

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