Air treatment system
Patent Information
- Authority / Receiving Office
- TW · TW
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2022-06-14
- Publication Date
- 2023-04-01
Smart Images
Figure TWG2TA000902644_001 
Figure TWG2TA000902644_002 
Figure TWG2TA000902644_003
Abstract
Description
[Technical Field]
[0001] This invention relates to an air handling system. [Previous Technology]
[0002] In hot and humid climates, air conditioning and space cooling are crucial. However, air conditioners consume a significant amount of electricity, thus contributing to greenhouse gas emissions. Desiccant cooling is an attractive energy-saving alternative to traditional air conditioners for achieving a cooling effect, but it has not yet been widely adopted on a commercial scale.
[0003] In a liquid desiccant cooling system, the liquid desiccant circulates between a dehumidifier and a regenerator. Process air passes through the concentrated and cooled liquid desiccant in the dehumidifier, for example, in a crossflow manner, transferring moisture and heat from the air to the liquid desiccant. The diluted liquid desiccant then enters the regenerator, where it is heated and moisture is absorbed from the diluted liquid desiccant using a scavenger air stream to regenerate the concentrated liquid desiccant. The concentrated liquid desiccant can then be reused in the dehumidifier.
[0004] However, there are many challenges in developing large-scale liquid desiccant cooling systems.
[0005] Accordingly, the most commonly used liquid desiccants are solutions of lithium chloride, calcium chloride, and lithium bromide (LiCl, CaCl2, and LiBr, respectively), which are typically regenerated using external energy sources such as waste heat or solar thermal energy at temperatures of approximately 80°C. Such high temperatures mean that the technology faces challenges in widespread use.
[0006] In addition, due to the toxicity of desiccants, especially at high speeds (e.g., exceeding 10,000 cfm (16,990 m3 / hr)), liquid desiccants remaining in the processed air can cause health problems, especially when desiccant droplets float in the air into a cooled enclosed space, or when liquid desiccants come into contact with personnel performing system maintenance.
[0007] As the partial pressure of the liquid desiccant increases, its temperature rises above 30°C, reducing its effectiveness in capturing moisture from the processed air. This may necessitate providing a continuous cooling source to control the temperature rise, especially when the processed air treated by the desiccant enters the system at temperatures above 30°C in hot climates.
[0008] The use of typical inorganic liquid desiccants limits their widespread use in dehumidification systems within typical HVAC units due to economic feasibility. For example, LiCl can cost $1300 per 100L. More affordable desiccants are needed.
[0009] There are environmental challenges associated with the use of liquid desiccant solutions, which include LiCl, CaCl2 and LiBr, and may cause significant damage to air conditioning systems due to their corrosiveness.
[0010] Solar-powered dehumidification systems offer the possibility of sustainably regenerating diluted desiccant solutions. However, solar radiation may only be available intermittently, which could impose practical limitations on its application in the HVAC industry.
[0011] Regenerating liquid desiccants using waste heat requires a permeable external supply source. This may limit the use of such a system to locations where a suitable waste heat source is available, thereby reducing the attractiveness and practicality of the concept.
[0012] Another problem is the crystallization of liquid desiccants. As the temperature decreases, crystallization can occur in liquid desiccant solutions stored at high concentrations, putting pressure on the circulating pump. Aqueous salt desiccants may require continuous stirring to prevent crystallization, which in turn increases the unit's energy consumption. [Summary of the Invention]
[0013] The present invention aims to provide an air handling system that improves upon existing systems. Here, "handling air" refers to the air to be handled. The benefits of the invention discussed herein are most evident in handling air with high humidity and temperature.
[0014] Accordingly, according to a first aspect of the present invention, an air handling system is provided, comprising: a dehumidification unit including a liquid desiccant system, the liquid desiccant system including a liquid desiccant for dehumidifying the handled air; an indirect evaporative cooling unit for cooling the handled air from the dehumidification unit and for cooling the liquid desiccant; and a vapor compression unit including a compressor, a condenser and an evaporator for further cooling the handled air from the indirect evaporative cooling unit.
[0015] Therefore, the system of the first embodiment of the present invention can be considered as a hybrid system comprising three units: a dehumidification unit, an indirect evaporative cooling unit, and a vapor compression unit, which are integrated synergistically to improve energy efficiency and to process 100% fresh air at a large-scale commercial capacity (e.g., at least 20,000 m³ / hr). This system can be used to independently cool indoor or outdoor spaces in hot and humid climates. The system can be fully automated to manage the operating modes of the different units according to external weather conditions and gas supply requirements.
[0016] Therefore, the first aspect of the air handling system of the present invention includes a dehumidification unit, which includes a liquid desiccant system.
[0017] The liquid desiccant system includes a liquid desiccant for absorbing moisture from processed air, and preferably includes a dehumidifier, which includes a dryer in which the processed air comes into contact with the desiccant. The liquid desiccant system preferably includes one or more heat exchangers for controlling the temperature of the desiccant.
[0018] The properties of liquid desiccants, such as electrical conductivity, dynamic viscosity, specific heat capacity, and density, as well as operating parameters such as boiling point elevation, regeneration temperature, and energy storage density, determine their potential as liquid desiccants. Among these properties, surface vapor pressure is one of the most important parameters affecting heat and mass transfer in a dehumidifier. Furthermore, the liquid desiccant is preferably odorless, non-toxic, non-flammable, and inexpensive.
[0019] A preferred desiccant for this liquid desiccant system is potassium formate (HCOOK). HCOOK is less corrosive, less expensive, and has a lower crystallization temperature than conventional aqueous desiccant salts. HCOOK can effectively dehumidify air with high moisture content. The preferred temperature for regenerating a weak HCOOK solution can be as low as 45°C.
[0020] Water-soluble HCOOK solution has low toxicity and viscosity, and is non-corrosive and non-volatile. In addition, at high solution concentrations, HCOOK can achieve a high degree of vapor pressure depression while maintaining a crystallization temperature below 0°C, which is superior to traditional liquid desiccants.
[0021] Using HCOOK as a liquid desiccant can reduce the atmospheric humidity ratio by more than 6 g / kg, thereby reducing latent heat and the relative humidity of the treated air. This could potentially reduce energy consumption by 20% to 30%.
[0022] Preferred liquid desiccants for use in liquid desiccant systems therefore include solutions containing water-soluble HCOOK, which are essentially composed of solutions containing water-soluble HCOOK, or consist of solutions containing HCOOK. Preferably, the only desiccant used in the liquid desiccant is HCOOK.
[0023] The liquid desiccant system preferably includes a dehumidifier, which preferably includes a dryer in which the process air comes into contact with the liquid desiccant. In the dryer, the process air passes through the liquid desiccant, for example in a cross-flow manner, transferring moisture and heat from the process air to the liquid desiccant. The dryer is preferably equipped with a controller to control the flow rate and distribution of the liquid desiccant, thereby ensuring optimal absorption efficiency of moisture and heat by controlling the ratio of liquid to process air.
[0024] The dryer preferably includes an eliminator to help prevent liquid desiccant from remaining in the treated air. The eliminator may be configured, for example by its geometry, thickness, layering, spacing, and / or the materials used, to prevent the retention of liquid desiccant at speeds exceeding 10,000 cfm (approximately 17,000 m³ / hr). Therefore, the eliminator preferably helps eliminate health problems associated with the retention of liquid desiccant with a minimum pressure drop of less than 3%.
[0025] Preferably, the dehumidifier is also equipped with a collection tank for collecting liquid desiccant solution from the dryer, a pump for feeding the liquid desiccant into and extracting it from the collection tank, and a spray system for spraying the liquid desiccant into the processed air.
[0026] In the first embodiment of the air handling system of the present invention, the liquid desiccant is cooled by an indirect evaporative cooling unit. In this regard, the liquid desiccant system preferably includes one or more heat exchangers for controlling the temperature of the liquid desiccant. The one or more heat exchangers preferably include liquid-liquid sensible heat exchangers, more preferably a series of liquid-liquid sensible heat exchangers. The one or more heat exchangers may be plate counter-current heat exchangers to improve heat transfer efficiency. The one or more heat exchangers preferably use chilled water to lower the temperature of the liquid desiccant. In a preferred embodiment, the liquid desiccant system includes a series of liquid-liquid sensible plate heat exchangers through which the liquid desiccant is fed from and into a collection tank. In a preferred embodiment, water from the indirect evaporative cooling unit is used in the one or more heat exchangers to cool the temperature of the liquid desiccant. Therefore, in a preferred embodiment, the liquid desiccant system includes a series of liquid-to-liquid sensed plate heat exchangers in a closed loop, which are in fluid communication with an indirect evaporative cooling unit and use water from the indirect evaporative cooling unit to cool the liquid desiccant.
[0027] The liquid desiccant system preferably includes a regenerator for concentrating the liquid desiccant diluted by absorbing moisture from the processed air. Within the regenerator, the relatively hot, diluted liquid desiccant solution is exposed to a purge airflow, generated, for example, by an axial fan, the airflow being proportional to the regenerated desiccant, and moisture is transferred from the diluted liquid desiccant solution to the purge air due to vapor pressure differences. The regenerator can regenerate the liquid desiccant, for example, a solution containing HCOOK, at a rate greater than 25 g / s. The liquid desiccant system is preferably configured and controlled to transfer the liquid desiccant from the dehumidifier to the regenerator when the concentration of the liquid desiccant drops below a predetermined threshold. For example, this threshold concentration can be below 60%.
[0028] The regenerator preferably includes a heat exchanger for increasing the temperature of the liquid desiccant, and preferably also includes an axial fan for introducing purge air. Preferably, it may further include a liquid injection system for injecting heated and diluted liquid desiccant into the purge air stream, and a pump for conveying liquid desiccant around the regenerator. The heat exchanger may be a liquid-to-liquid sensed plate heat exchanger to improve heat transfer efficiency. The heat exchanger can increase the temperature of the liquid desiccant within the regenerator to above 45°C. In a preferred embodiment, the heat exchanger utilizes internal waste heat from the compressor of the vapor compression unit, which has the additional advantage of reducing the compressor temperature, thereby improving its operating efficiency. In these embodiments, a liquid (e.g., water) can bring waste heat from the compressor to the heat exchanger and circulate in a closed loop independent of the refrigerant used in the vapor compression unit to avoid any cross-contamination between units.
[0029] The regenerator preferably includes an eliminator for reducing the loss of liquid desiccant in the purging airflow during regeneration. The eliminator preferably includes a cellulose pad having a preferred geometry, thickness, and spacing.
[0030] Therefore, the preferred dehumidification process within the dehumidification unit of the first-state system of the present invention can be summarized as follows. A liquid desiccant, stored in a dehumidifier collection tank, has a relatively high concentration and a low temperature and enters the dryer. In the dryer, the liquid desiccant comes into contact with the process air. Since the vapor pressure of the liquid desiccant is lower than that of the dehumidified process air, heat and moisture are transferred from the process air to the liquid desiccant, thus drying the process air and increasing the temperature and concentration of the liquid desiccant. The liquid desiccant then flows out of the dryer and passes through one or more heat exchangers to lower its temperature and thus its vapor pressure, thereby increasing its ability to absorb moisture from the process air. It then re-enters the collection tank, where a pump circulates the desiccant from the collection tank through a spray system and into the dryer at a controlled liquid flow rate. When the liquid desiccant is sufficiently diluted, for example, when the concentration drops below a threshold level (e.g., 60%), the liquid desiccant is transferred to a regenerator. Here, the diluted liquid desiccant is heated, preferably by passing it through a heat exchanger to increase its vapor pressure. Purging air is then passed through the heated and diluted liquid desiccant to remove moisture (the vapor pressure of the liquid desiccant is higher than that of the purging air), thereby concentrating the liquid desiccant. The concentrated liquid desiccant is then returned to the collection tank. The dehumidification and regeneration process then continues.
[0031] The first-state air handling system of the present invention further includes an indirect evaporative cooling unit for cooling air from the dehumidification unit and for cooling liquid desiccant.
[0032] Evaporative cooling is a process of cooling air by the evaporation of water. Therefore, water absorbs a large amount of heat to evaporate (i.e., it has a high enthalpy of vaporization), and evaporative cooling relates to using the thermal energy in the air to change the phase of water from liquid to gas. Indirect evaporative cooling is a process in which processed air is cooled by exchanging heat with a humidified scavenging air stream, and in this process, the processed air stream and the scavenging air stream do not directly mix. This helps prevent, for example, the transfer of moisture and contaminants between the processed air stream and the scavenging air stream.
[0033] Therefore, in the air handling system of the first embodiment of the present invention, dehumidified air from the dehumidification unit enters the indirect evaporative cooling unit and is cooled by heat exchange with the humidified purge air stream in the indirect evaporative cooling unit. Sensible heat from the handling air is absorbed by water in the purge air stream, thus cooling the handling air. Energy can be saved (e.g., up to 30%) due to the reduced load on the evaporator coil of the vapor compression unit. The temperature reduction of the handling air can be up to 15°C based on the heat transfer efficiency between the two airflows. The indirect evaporative cooling unit preferably includes a cross-flow plate type sensing heat exchanger for heat exchange between the handling air and the humidified purge air stream, and preferably also includes a water sprayer for humidifying the purge air stream. The water sprayer is preferably configured to be controllable by a controller to obtain optimal air-water heat transfer efficiency.
[0034] In a preferred embodiment, the cooled purge air leaving the indirect evaporative cooling unit passes through the condenser of the vapor compression unit to assist in the cooling of the refrigerant. This reduces the pressure of the refrigerant, thereby reducing the load on the compressor of the vapor compression unit and thus reducing its power consumption. The indirect evaporative cooling unit preferably further includes an eliminator, which in this preferred embodiment is configured to help prevent water droplets entrained in the purge air from entering the condenser coils and also maintains the water level in the indirect evaporative cooling unit.
[0035] The indirect evaporative cooling unit is also used to cool the liquid desiccant, and in this respect, water from the indirect evaporative cooling unit can be transferred to a dehumidifier to cool the liquid desiccant after contact with the process air, for example, within one or more heat exchangers. The indirect evaporative cooling unit preferably includes a water collection tank for holding and collecting water for use with the spray nozzle. This water can therefore be used to cool the liquid desiccant as well as to cool the purge air. The water collection tank of the indirect evaporative cooling unit can also be used to supply water for adiabatically cooling the condenser of the vapor compressor unit using a direct evaporation pad as described herein, and can also be used to store cold condensate from the evaporator coils of the vapor compressor unit.
[0036] The first-state air handling system of the present invention further includes a vapor compression unit for cooling the processed air from the indirect evaporative cooling unit.
[0037] Vapor compression cooling is a process in which a refrigerant is compressed in a compressor, cooled in a condenser, and then expanded and evaporated via an expansion valve or throttle valve. Therefore, typically a gaseous refrigerant is compressed in a compressor to increase its temperature and pressure. The compressed refrigerant then passes through a condenser, where heat is transferred from the refrigerant to the passing air, thereby lowering the refrigerant's temperature while maintaining a substantially constant pressure. The cooled refrigerant then expands, for example, via an expansion valve or throttle valve, thereby lowering its pressure and temperature. The refrigerant then absorbs heat from its surroundings and evaporates, thus cooling its surroundings.
[0038] The vapor compression unit used in the first embodiment of the air handling system of the present invention thus includes a compressor, a condenser, and an evaporator. As described above, in a preferred embodiment, the condenser is cooled by cooled purge air exiting the indirect evaporative cooling unit to assist in cooling the refrigerant. This reduces the load on the compressor and its power consumption.
[0039] The vapor compression unit can employ direct evaporative cooling to improve efficiency. Therefore, the purge airflow can be cooled by direct evaporative cooling and assisted by a condenser. The purge airflow can be moistened by, for example, a moisture-absorbing pad wetted with water, which may come from one or more spray nozzles. This pad may be, for example, a cellulose pad. In a preferred embodiment, the water comes from an indirect evaporative cooling unit, such as the water tank described herein. Cooling the refrigerant reduces its pressure, thus reducing the compressor load and thereby improving system performance and efficiency. For example, using direct evaporative cooling in this manner can reduce the compressor's power consumption and improve its coefficient of performance by more than 5%.
[0040] It should be noted that at high relative humidity (RH), such as at least 80% relative humidity, the improvement in efficiency of the vapor compression unit by direct evaporative cooling may become negligible relative to the performance of the condenser. Therefore, the water supply can be controlled to be shut off at higher relative humidity, for example, when RH > 80%.
[0041] The process air eventually passes through an evaporator to be cooled to the required temperature. When the process air is cooled below its dew point, the collected cold condensate can be returned to the indirect evaporative cooling unit to lower the temperature of the water used in the indirect evaporative cooling unit, thus helping to lower the temperature of the liquid desiccant by heat exchange, as described above.
[0042] As described above, in a preferred embodiment, waste heat from the compressor of the vapor compression unit is used to heat the diluted liquid desiccant during the regeneration process via heat exchange. This improves the efficiency of the compressor during the regeneration process.
[0043] The processing air leaving the vapor compression unit can then be blown into the space that needs to be cooled, preferably by means of an electronically commutated (EC) fan, to enhance control and reduce energy consumption.
[0044] According to the present invention, a solution containing potassium formate is provided in the second state sample for use as a liquid desiccant in the air handling system described above. Preferably, HCOOK is the only desiccant present in the liquid desiccant. [Simplified Explanation of the Diagram]
[0045] Illustrative embodiments of the invention will now be described in detail with reference to the accompanying drawings, in which:
[0046] FIG1 is a schematic diagram of an embodiment of an air handling system according to a first state according to the present invention;
[0047] Figure 2 is a schematic diagram illustrating the dehumidification unit of the embodiment shown in Figure 1; and
[0048] Figure 3 is a schematic diagram showing the indirect evaporative cooling unit and vapor compression unit in the embodiment shown in Figure 1.
Implementation Method
[0049] In the diagram, the processing air is indicated by the arrow with reference symbol A. The processing air enters the system on the right side of Figure 1 and leaves the system on the left side of Figure 1.
[0050] Therefore, FIG1 illustrates an air handling system according to a first aspect of the present invention. The air handling system includes: a dehumidification unit for dehumidifying the handled air, an indirect evaporative cooling unit for cooling the handled air from the dehumidification unit and for cooling a liquid desiccant, and a vapor compression unit for further cooling the handled air from the indirect evaporative cooling unit, which are generally represented by reference numerals 10, 100 and 200, respectively.
[0051] The dehumidification unit 10 includes a liquid desiccant system, which includes a dehumidifier (generally indicated by reference numeral 20) and a regenerator (generally indicated by reference numeral 30). The dehumidification unit 10 is also shown in FIG2.
[0052] The dehumidifier 20 used in the illustrative embodiment includes: a desiccant for absorbing moisture from the processed air A (the flow path of which is shown in Figures 1 and 2), a dryer 21 in which the processed air comes into contact with the desiccant, a collection tank 24, and one or more heat exchangers 22 for controlling the temperature of the desiccant.
[0053] A preferred desiccant for dehumidifiers is a solution containing water-soluble potassium formate (HCOOK). HCOOK is less corrosive and cheaper than conventional water-soluble desiccant salts, and it has a low crystallization temperature. HCOOK can effectively dehumidify air with high moisture content. The preferred temperature for regenerating a weak HCOOK solution is above 45°C.
[0054] Water-soluble HCOOK solution has low toxicity and viscosity, and is non-corrosive and non-volatile. In addition, at high solution concentrations, HCOOK can be superior to traditional liquid desiccants by promoting a high degree of vapor pressure reduction while maintaining a crystallization temperature below 0°C.
[0055] Using HCOOK as the desiccant in dehumidifier 20 can reduce the atmospheric humidity ratio by more than 6 g / kg, which results in a reduction in latent heat and a decrease in the relative humidity of the treated air A. This may potentially reduce energy consumption by 20% to 30%.
[0056] The dehumidifier 20 includes a dryer 21 in which processed air A comes into contact with a liquid desiccant. In the dryer 21, the processed air A passes through the liquid desiccant in a cross-flow manner to transfer moisture and heat from the processed air A to the liquid desiccant. In an illustrative embodiment, the liquid desiccant is held in a collection tank 24, and the processed air A is sprayed with the liquid desiccant by a sprayer 23. The dryer 21 is equipped with a controller (not shown) to control the flow rate and distribution of the liquid desiccant, thereby ensuring optimal absorption efficiency of moisture and heat by controlling the ratio of liquid to processed air A.
[0057] The dryer 21 preferably includes an eliminator (not shown) to help prevent liquid desiccant from remaining in the treated air. The eliminator may be configured, for example by its geometry, thickness, spacing, layering, and / or the materials used, to prevent the retention of liquid desiccant at speeds exceeding 10,000 cfm (approximately 17,000 m³ / hr). Therefore, the eliminator preferably helps eliminate health problems associated with the retention of liquid desiccant with a minimum pressure drop of less than 3%.
[0058] The dehumidifier 20 includes a plurality of heat exchangers 22 for controlling the temperature of the liquid desiccant. In an illustrative embodiment, the heat exchangers 22 are plate type counterflow liquid-liquid sensible heat exchangers, and use cold water from the indirect evaporative cooling unit 100 to cool the liquid desiccant.
[0059] The liquid desiccant system includes a regenerator 30 for concentrating the liquid desiccant that has been diluted by absorbing moisture from the process air A in the dryer 21. Within the regenerator 30, the relatively hot diluted liquid desiccant solution is exposed to a scavenger air stream (indicated by arrow B) provided by an axial fan 36, and moisture is transferred from the diluted liquid desiccant solution to the scavenger air B due to vapor pressure differences. The regenerator 30 can regenerate the liquid desiccant at a rate greater than 25 g / s. The liquid desiccant system is configured and controlled to transfer liquid desiccant from the dehumidifier 21 to the regenerator 30 when the concentration of the liquid desiccant decreases below a predetermined threshold. For example, this threshold concentration can be below 60%.
[0060] In the illustrative embodiment, the regenerator 30 includes a liquid desiccant reservoir 33 for receiving diluted liquid desiccant from the dehumidifier 20. The regenerator 30 also includes a liquid-to-liquid-sensible plate countercurrent heat exchanger 31 to raise the temperature of the liquid desiccant. The heat exchanger 31 can raise the temperature of the liquid desiccant within the regenerator 30 to, for example, above 45°C. In the illustrative embodiment, the heat exchanger 31 utilizes waste heat from the compressor 201 of the vapor compression unit 200, which has the additional advantage of reducing the temperature of the compressor 201, thereby improving its operating efficiency. In the illustrative embodiment, the waste heat from the compressor 201 is used to heat water passing through the heat exchanger 35, which then heats the liquid desiccant in the heat exchanger 31, as shown in Figures 1 and 2.
[0061] In an illustrative embodiment, the regenerator 30 includes: a sprayer 34 for spraying hot liquid desiccant into the purging air B, and an eliminator 32 for reducing liquid desiccant loss in the purging air stream B during regeneration. The eliminator 32 may include a cellulose pad.
[0062] The dehumidification process within the dehumidification unit 10 of the first-state system of the present invention, as shown in Figures 1 and 2, is described below. A liquid desiccant with a relatively high concentration ("strong") and low temperature enters the dryer 21 from the collection tank 24 via a sprayer 23. In the dryer 21, the liquid desiccant is sprayed into the process air A. Since the vapor pressure of the liquid desiccant is lower than that of the dehumidified process air A, heat and moisture are transferred from the process air A to the liquid desiccant, thus cooling and drying the process air A, increasing the temperature of the liquid desiccant and decreasing its concentration. The warm liquid desiccant flows out of the dryer 21 into the collection tank 24, where its temperature is reduced by the heat exchanger 22 (and thus its vapor pressure is reduced to increase its ability to absorb moisture from the process air), and then it returns to the dryer 21. When the liquid desiccant is sufficiently diluted ("weak"), for example, when the concentration is reduced to below a threshold level (e.g., below 60%), it is transferred to the regeneration reservoir 33. The weak liquid desiccant passes through heat exchanger 31, thereby increasing its vapor pressure. The heated and diluted liquid desiccant is then transferred from heat exchanger 31 to atomizer 34, where it is sprayed into purge air B to remove moisture (the vapor pressure of the liquid desiccant is higher than that of the purge air), thus concentrating the liquid desiccant. The concentrated ("strong") liquid desiccant is then returned to collection tank 24. The flow path of the liquid desiccant is shown in Figures 1 and 2.
[0063] An illustrative embodiment of the first-state air handling system of the present invention further includes an indirect evaporative cooling unit 100 for cooling air from the dehumidification unit 10 and for cooling liquid desiccant, as shown in Figures 1 and 3.
[0064] Therefore, in the illustrative embodiment, the dehumidified processed air A from the dehumidification unit 10 enters the indirect evaporative cooling unit 100 and is cooled in the indirect evaporative cooling unit 100 by heat exchange with the humidified purge air stream (indicated by arrow C). The sensible heat from the processed air A is absorbed by the water in the purge air stream C, thereby cooling the processed air A. This can result in energy savings (e.g., up to 30%) due to the reduced load on the evaporative coil of the vapor compression unit. Depending on the heat transfer efficiency between the two air streams, the reduction in processed air temperature can be as high as 15°C. The indirect evaporative cooling unit 100 shown in the figure includes: an interleaved flow sensible plate heat exchanger 102 for heat exchange between the processed air A and the humidified purge air stream C, and a water sprayer 103 for humidifying the purge air stream with water from the water collection tank 101. The water sprayer 103 is preferably configured with a sufficient number of nozzles that are evenly distributed to cover the clear airflow C, and can be controlled by a controller (not shown) to achieve optimal heat transfer efficiency between air and water.
[0065] The cooled purge air C leaving the indirect evaporative cooling unit 100 passes through the condenser 202 of the vapor compression unit 200 to assist in cooling the refrigerant in the vapor compression unit. This reduces the pressure of the refrigerant, thereby reducing the load on the compressor 201 of the vapor compression unit 200, and thus reducing its power consumption. In an illustrative embodiment, the indirect evaporative cooling unit 100 further includes an eliminator 104 configured to help prevent water droplets from being entrained by the purge air into the coils of the condenser 202, and also to maintain the water level in the indirect evaporative cooling unit 100. After passing through the condenser 202, the purge air C is discharged by the fan 105.
[0066] As shown in the figure, water from the indirect evaporative cooling unit 100 flows to the dehumidifier 20 to cool the liquid desiccant after contacting the processing air A in the heat exchanger 22.
[0067] An illustrative embodiment of the first-state air handling system of the present invention further includes a vapor compression unit 200 for cooling the processing air A from the indirect evaporative cooling unit 100, as shown in Figures 1 and 3.
[0068] The vapor compression unit 200 includes a compressor 201, a condenser 202, and an evaporator 206. As described above, in the illustrative embodiment, the condenser 202 is cooled by cooled purge air C exiting the indirect evaporative cooling unit 100 to assist in the cooling of the refrigerant. This reduces the load on the compressor 201 and reduces power consumption. In the illustrative embodiment, the vapor compression unit 200 employs direct evaporative cooling to improve efficiency. Therefore, the purge air stream (indicated by arrow D) can be cooled by direct evaporative cooling, and it passes through the condenser 202 to assist in cooling. The purge air stream D can be moistened, for example, by passing through a moisture-absorbing pad 203, which is moistened by water from a water sprayer 204. This pad can be, for example, a cellulose pad. In the illustrative embodiment, the water source is from the water collection tank 101 of the indirect evaporative cooling unit as shown. Cooling the refrigerant reduces its pressure, thereby reducing the load on the compressor 201 and contributing to improved system performance and efficiency. For example, by using direct evaporative cooling in this manner, the power consumption of compressor 201 can be reduced, and the coefficient of performance can be increased by more than 5%. It should be noted that at high relative humidity (RH), such as 80% or higher, the improvement in efficiency of vapor compression unit 200 by direct evaporative cooling may become negligible relative to the performance of condenser. Therefore, the water supply can be controlled to be shut off at higher relative humidity, such as when RH > 80%.
[0069] The processing air A passes through the coil of the evaporator 206 to reduce its temperature. The processing air A can be cooled below its dew point, and the water collected in this stage can be returned to the water collection tank 101 of the indirect evaporative cooling unit to reduce the temperature of the water used in the indirect evaporative cooling unit 100, thus helping to reduce the temperature of the liquid desiccant by heat exchange, as described above.
[0070] As described above, and as shown in Figures 1 and 2, in a preferred embodiment, waste heat from the compressor 201 of the vapor compression unit 200 is used to heat the diluted liquid desiccant during the regeneration process via heat exchange. This improves the efficiency of the compressor 201.
[0071] The processing air A leaving the vapor compression unit 200 is then blown into the space that needs to be cooled by the electronic commutation fan 205.
[0072] It should be understood that the embodiments described above are for illustrative purposes only. In practical applications, the invention can be applied to many different configurations. Detailed embodiments are readily implemented by those skilled in the art.
Claims
1. An air handling system, comprising: The dehumidification unit includes a liquid desiccant system comprising a liquid desiccant for dehumidifying the processed air; An indirect evaporative cooling unit is used to cool the processing air from the dehumidification unit and to cool the liquid desiccant. as well as A vapor compression unit, including a compressor, a condenser, and an evaporator, is used to further cool the processed air from the indirect evaporative cooling unit.
2. The air handling system as described in claim 1, wherein, The air handling system is configured to handle fresh air at a capacity of at least 20,000 m³ / hr.
3. The air handling system as described in claim 1 or 2, wherein, The liquid desiccant consists of a solution containing potassium formate.
4. The air handling system as described in claim 3, wherein, The air handling system is configured to reduce the atmospheric humidity ratio by more than 6g / kg.
5. An air handling system as described in any of the preceding claims, wherein, The liquid desiccant system includes one or more heat exchangers for controlling the temperature of the liquid desiccant.
6. The air handling system as described in claim 5, wherein, The liquid desiccant system includes a series of liquid-to-liquid sensed plate countercurrent heat exchangers.
7. The air handling system as described in claim 5 or 6, wherein, The one or more heat exchangers are in fluid communication with the indirect evaporative cooling unit for using water from the indirect evaporative cooling unit to cool the liquid desiccant.
8. An air handling system as described in any of the preceding claims, wherein, The liquid desiccant system includes a dryer with an eliminator for reducing the retention of the liquid desiccant in the processed air.
9. The air handling system as described in claim 8, wherein, The eliminator is configured to reduce the retention of the liquid desiccant with a minimum pressure drop of less than 3% at speeds exceeding 8,000 cfm.
10. An air handling system as described in any of the preceding claims, wherein, The liquid desiccant system includes a regenerator for concentrating the liquid desiccant that has been diluted due to absorbing moisture from the processed air.
11. The air handling system as described in claim 10, wherein, The regenerator is configured to regenerate the liquid desiccant at a rate greater than 25 g / s.
12. The air handling system as described in claim 10 or 11, wherein, The liquid desiccant system is configured to deliver the liquid desiccant to the regenerator when the concentration of the liquid desiccant drops below a predetermined threshold.
13. The air handling system as described in claim 12, wherein, The threshold is less than 60%.
14. The air handling system as described in any one of claims 10 to 13, wherein, The regenerator includes a heat exchanger for increasing the temperature of the liquid desiccant.
15. The air handling system as described in claim 14, wherein, This heat exchanger is a liquid-to-liquid sensing heat exchanger.
16. The air handling system as described in claim 14 or 15, wherein, The heat exchanger uses internal waste heat from the compressor of the vapor compression unit to heat the liquid desiccant.
17. The air handling system as described in any one of claims 10 to 16, wherein, The regenerator includes an eliminator to reduce the loss of the liquid desiccant in the purge airflow during the regeneration process.
18. The air handling system as described in claim 17, wherein, The eliminator comprises one or more cellulose pads.
19. An air handling system as described in any of the preceding claims, wherein, The indirect evaporative cooling unit includes a cross-flow plate type heat exchanger for exchanging sensible heat between the process air and the humidified purge air stream.
20. The air handling system as described in claim 19, wherein, The air handling system is configured to allow cooled purge air leaving the indirect evaporative cooling unit to pass through the condenser of the vapor compression unit.
21. An air handling system as described in any of the preceding claims, wherein, The indirect evaporative cooling unit includes an eliminator configured to help prevent water droplets from being entrained in the purging air.
22. An air handling system as described in any of the preceding claims, wherein, The vapor compression unit is configured to use direct evaporative cooling.
23. The air handling system as described in claim 22, wherein, The air handling system is configured to cool the purge airflow by direct evaporative cooling and to pass the cooled purge airflow through the condenser to assist in cooling.
24. The air handling system as described in claim 23, wherein, The purging airflow system is moistened via a moisture-absorbing pad to assist in the adiabatic cooling of the condenser.
25. The air handling system as described in claim 24, wherein, The absorbent pad consists of a cellulose pad.
26. The air handling system as described in claim 24 or 25, wherein, The air handling system is configured to obtain water from the indirect evaporative cooling unit to wet the moisture-absorbing pad.
27. An air handling system as described in any of the preceding claims, wherein, The air handling system is configured to return water captured from the coils of the evaporator in the vapor compression unit to the indirect evaporative cooling unit.
28. The air handling system as described in any of the preceding claims further includes an electronically commutating fan for blowing the cooled and dehumidified processed air into the desired space.
29. Use of a solution containing potassium formate, wherein the use is as a liquid desiccant in an air handling system as described in any of the preceding claims.