WO2008108740A1 - System and method for atmospheric water generation over extended range of ambient temperatures - Google Patents

System and method for atmospheric water generation over extended range of ambient temperatures Download PDF

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Publication number
WO2008108740A1
WO2008108740A1 PCT/SG2008/000061 SG2008000061W WO2008108740A1 WO 2008108740 A1 WO2008108740 A1 WO 2008108740A1 SG 2008000061 W SG2008000061 W SG 2008000061W WO 2008108740 A1 WO2008108740 A1 WO 2008108740A1
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WIPO (PCT)
Prior art keywords
water
air
generation system
evaporator
measured
Prior art date
Application number
PCT/SG2008/000061
Other languages
French (fr)
Inventor
Toh Chin Eric Tan
Chee Keong Vincent Oh
Lee Thian Edmund Tan
Original Assignee
Sirius Water Technologies Pte Ltd
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Application filed by Sirius Water Technologies Pte Ltd filed Critical Sirius Water Technologies Pte Ltd
Publication of WO2008108740A1 publication Critical patent/WO2008108740A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F3/00—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems
    • F24F3/12—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling
    • F24F3/14—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling by humidification; by dehumidification
    • F24F3/1405—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling by humidification; by dehumidification in which the humidity of the air is exclusively affected by contact with the evaporator of a closed-circuit cooling system or heat pump circuit
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
    • B01D5/0003—Condensation of vapours; Recovering volatile solvents by condensation by using heat-exchange surfaces for indirect contact between gases or vapours and the cooling medium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
    • B01D5/0057—Condensation of vapours; Recovering volatile solvents by condensation in combination with other processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
    • B01D5/0057—Condensation of vapours; Recovering volatile solvents by condensation in combination with other processes
    • B01D5/0075—Condensation of vapours; Recovering volatile solvents by condensation in combination with other processes with heat exchanging
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
    • B01D5/0078—Condensation of vapours; Recovering volatile solvents by condensation characterised by auxiliary systems or arrangements
    • B01D5/009—Collecting, removing and/or treatment of the condensate
    • E—FIXED CONSTRUCTIONS
    • E03—WATER SUPPLY; SEWERAGE
    • E03B—INSTALLATIONS OR METHODS FOR OBTAINING, COLLECTING, OR DISTRIBUTING WATER
    • E03B3/00—Methods or installations for obtaining or collecting drinking water or tap water
    • E03B3/28—Methods or installations for obtaining or collecting drinking water or tap water from humid air
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A20/00—Water conservation; Efficient water supply; Efficient water use

Definitions

  • the present invention relates to drinking water generation, and more particularly apparatus and method of atmospheric water vapor extraction system having an innovative dual-purposed air pre-conditioning means which makes the system well-suited in many indoor and outdoor, fixed and mobile applications in not only tropical regions, but also temperate areas with ambient temperatures well below what conventional systems are designed to operate.
  • the atmospheric water generation system of the present invention provides a solution to water generation without the need for extensive water distribution networks, the system rides on existing refrigeration and central air systems to provide the necessary refrigerant compression and condensation capability.
  • the present system offers a cost-effective water making solution suitable for fixed and mobile units used in both indoor and outdoor environments.
  • said atmospheric water generation system comprises an evaporator, air filter and extractor, internal water storage tank, means of removing water stored in said internal tank to external appliances and storage units, temperature, humidity and water level measurement means, fluid dryers, capillary tubes, actuator valves together with an air pre-conditioning means for conditioning convection currents to boost water extraction efficiency at lower ambient temperatures.
  • the present system is well suited for temperate areas with ambient temperatures well below what conventional systems are designed to operate.
  • the air preconditioning means of the present system is also designed to suppress the undesired growth of mold and algae on the surfaces of the evaporator, water droplet collection tray and other systems housed in the water generation compartment.
  • the hot fluid used by the air pre-conditioning means is preferably supplied by the existing refrigerant source, hence the set-up and operational costs of said air pre-conditioning means is relatively low.
  • the system completes with a controller device capable of determining an appropriate mode of operation in accordance with measured temperature, humidity and water level data, and said controller device controls and powers all parts and subsystems, logs, stores, analyses and displays measured and control data.
  • FIG. 1 illustrates a typical standalone atmospheric water extraction system available commercially (prior art).
  • FIG. 2 illustrates the functional block diagram of the atmospheric water extraction system of the present invention.
  • FIG. 3 shows the operational flow of said atmospheric water generation system.
  • FIG. 1 illustrates a typical standalone atmospheric water extraction system available commercially.
  • the system employs a fluid refrigerant 171, 172, 173 to transfer heat out of an evaporator 110 such that the temperature on said evaporator surfaces is sufficiently low for condensation to take place.
  • Cold gaseous refrigerant 171 flows into a compressor 120 which pressurizes the fluid and as a result, said refrigerant becomes hotter and changes state from gas to liquid.
  • a condenser 130 is used to radiate or reject the heat built up in hot refrigerant 172.
  • the partially cooled refrigerant 173 flows into said evaporator 110 through a small aperture (not shown).
  • the pressure of said liquid refrigerant 173 drops and evaporates into gas which absorbs heat from the ambient air and objects.
  • a fan 160 is used to improve air circulation 161 and evaporation efficiency.
  • Water droplets 180 condensed on the surface of evaporator 110 are collected, treated with a filter 150 and stored in a tank 140 for consumption.
  • the condenser 130 and compressor 120 are not parts of the system as refrigerant 173, 171 can be supplied from an existing refrigeration system. Said alternative system works according to the same compression cycle and thermal energy exchange between ambient air and refrigerant of said standalone system 100.
  • the required working temperatures for conventional water extraction systems are typically above 18 0 C - 2O 0 C. Condensation occurs when a surface is cooler than the dew point temperature (condensation threshold temperature) of the air surrounding the surface. At this temperature, the air has a relative humidity equivalent to 100% and it becomes saturated with water. Said dew point temperature is dependent of both air temperature and humidity.
  • a conventional water extraction system needs to achieve a threshold temperature of 4 0 C on its evaporator surface when the ambient air has a temperature of 2O 0 C and relative humidity of 35%. This surface temperature requirement is excessive for many refrigeration systems, and frost may develop on said evaporator surfaces which could greatly dampen the efficiency of water extraction and even cause damages.
  • Water extraction efficiency generally improves with higher ambient temperature and / or relative humidity.
  • mold and other fungi start to grow and colonize said evaporator 110 and other parts such as the drip tray typically employed in commercial water extraction systems.
  • the undesirable growth of mold and fungi attracts dust and promotes excessive growth of harmful bacteria, which could severely undermine the air flow efficiency and water quality. This in turn results in higher operational and maintenance costs and longer downtimes.
  • the atmospheric water generation system of the present invention operates in conjunction with existing air conditioning and water storage systems to attain compact design, lower equipment and operational costs, and high level of flexibility in system design and integration.
  • Standalone water extraction systems 100 typically employ basic refrigeration configurations as more advanced features such as variable frequency or inverter drive commonly used in today's air system is too costly to be incorporated into said standalone systems. This directly affects the overall efficiency of standalone systems in term of the amount of water generated per unit of input energy.
  • the water vapor condensation system of the present invention incorporates a novel dual-purposed air pre-conditioning means to warm up cold air flowing into its evaporator when the ambient temperature falls below a predetermined value in temperate areas, and said pre-conditioning means is also used to inhibit growth of fungi and bacteria when the present system is used in tropical zones.
  • Said air pre-conditioning means is environment friendly as if relies primarily on hot fluid found in existing air conditioning systems.
  • FIG. 2 illustrates the functional block diagram of the atmospheric water extraction system of the present invention.
  • Hot liquid refrigerant 172 is supplied by an external refrigeration system or refrigerant source 210 via a fluid inlet duct 220.
  • Said hot refrigerant is typically tapped from the refrigerant outlet pipe of the condenser 130 (FIG. 1) of a refrigeration system.
  • Said external refrigerant source 210 is typically an existing refrigeration or central air system of any type provided that said existing system 210 can supply sufficient amount of refrigerant to chill the surfaces of the evaporator 110 to a temperature below the corresponding dew point temperature.
  • Said fluid inlet duct 220 further branches into first 221 and second 222 branch fluid ducts.
  • Said first branch fluid duct 221 is in communication with a first actuator valve 231 which is connected in series with a first fluid dryer 241.
  • the outlet of said first fluid dryer 241 is in communication with the inlet of a first capillary tube 251 having its outlet connected to the inlet of an evaporator 110.
  • the outlet of said evaporator is in communication with a fluid return duct 228 which directs cold vaporized refrigerant 171 back to said external refrigerant source 210.
  • Said second branch fluid duct 222 is in communication with a second actuator valve 232 having its outlet connected to the inlet of an air pre-conditioning means 215.
  • the outlet of said air pre-conditioning means 215 branches into a third branch fluid duct 223 and a fourth branch fluid duct 224.
  • Said third branch fluid duct 223 is in communication with a second fluid dryer 242 which is serially-connected to a second capillary tube 252 having its outlet connected to said inlet of said evaporator 110.
  • Said fourth branch fluid duct 224 connects a third in-line actuator valve 233 to said fluid return duct 228.
  • Said fluid return duct 228 is typically in communication with the inlet of the compressor 120 (FIG. 1) in said external refrigerant source 210.
  • Said first and second actuator valves are typically solenoid valves which can be activated and disabled by a controller device 280.
  • Check valves are preferably incorporated into said first and second actuator valves 231, 232 to prevent fluids in said first and second branch fluid ducts 221 & 222 from back- flowing into said external refrigerant source 210 via said fluid inlet duct 220 when said external refrigerant source is deactivated or when the pressure of said external refrigerant source system 210 has dropped excessively.
  • said first and second capillary tubes 251, 252 can be replaced by expansion valves.
  • the atmospheric water extraction system of the present invention comprises a water generation compartment 260 which houses said air pre-conditioning means 215, evaporator 110, and their associated parts and components which may include said second fluid dryer 242 and second capillary tube 252.
  • said water generation compartment 260 has a first aperture 261.
  • An air filter 218 is disposed in said first aperture 261 or in the vicinity of said first aperture.
  • said compartment 260 has a second aperture 262 with an air extractor 160 disposed in said second aperture or in the vicinity of said second aperture.
  • Said air filter 218 and air extractor 160 may be, as readily recognized by those skilled in the art, oriented in any way or disposed in any positions provided that they can operate to achieve effectively clean or dust-controlled air flow or circulation inside said water generation compartment 260.
  • a water droplet collection tray 270 is disposed beneath said evaporator 110 and said collection tray 270 is housed inside said water generation compartment 260. Water droplets collected by said collection tray 270 is led out of said water generation compartment 260 and directed into an internal water storage tank 140 having a water purifier 271 and an internal water level measurement means 272.
  • Said internal water level measurement means may be of the optical or float switch type.
  • Said water purifier 271 preferably comprises an ultra violet light and an ozone generator.
  • Said water purifier 271 may incorporate other filtration means including any mechanical, chemical or biological filtering systems suitable for purifying drinking water.
  • a fifth fluid duct 225 leads the drinkable water stored in said internal water storage tank 140 to any external appliances or storage means by means of a fluid pump 273.
  • Said controller device 280 electrically couples to said first, second and third actuator valves 231, 232 & 233, a temperature measurement means 290 and a relative humidity measurement means 291, said air extractor 160, internal water level measurement means 272 for detection of water level in internal water storage tank 140, external water level measurement means (not shown) for detection of water level in an external water storage unit, fluid pump 273, a standalone or integrated input means 281, a standalone or integrated display device 282, and any diagnosis data inputs for reporting malfunction or abnormal conditions of any parts including but not restricted to fluid pump 273, actuator valves 231 - 233, water purifier 271, air extractor 160, air pre-conditioning means 215 and evaporator 110.
  • Said controller device 280 may couple to a signaling interface module for relaying any control signals required to operate said external refrigerant source 210, and any other electrically driven parts and components that require instructions, signaling and / or electricity supply.
  • Said controller device 280 further comprises a processor for storing and executing software applications or embedded codes capable of generating appropriate control signals in accordance with a set of pre-programmed instructions. Measured data can be further processed in said controller device 280, and said processes include logging, reading and writing, storing and backing-up, analysis and displaying of measured and / or control data.
  • Controller device 280 can be coupled to an external computer via a wired or wireless data exchange interface 285.
  • the electrical power 286 supplied to said controller device 280 and the system as a whole may be single-phase or multi-phase alternating current or direct current or a combination of both alternating and direct currents tapped from power grids or mobile electricity generators such as those used on vessels, cruises, caravans, oil rigs, construction sites and other similar facilities.
  • Rust resistance materials can be applied to the surfaces of the enclosure housing all the sub-systems, parts and components of the water generation system of the present invention when it is used on ships, cruises, oil rigs and the like.
  • said air pre-conditioning means 215 together with second and third branch fluid ducts 221, 222, second and third actuator valves 232, 233, second fluid dryer 242 and capillary tube 252, can alternatively be implemented with an electrical heating element controlled and powered by said controller device 280.
  • Controller device 280 selects a first mode of operation denoted by
  • controller device 280 opens first actuator valve 231 to allow liquid refrigerant 172 from external refrigerant source 210 to flow into said first branch fluid duct 221.
  • Controller device 280 further shuts second actuator valve 232 and as a result, said liquid refrigerant 172 from said external refrigerant source bypasses air pre-conditioning means 215 and flows into evaporator 110 wherein refrigerant vaporizes and absorbs heat from the ambient air and objects.
  • the state of third actuator valve 233 is immaterial. Moisture and contaminants present in first branch fluid duct 221 is absorbed by first fluid dryer 241. Moisture comes from sources such as trapped air and system leaks, and it can cause freeze-ups and corrosion of metallic components if not removed. Fluid dryers 241, 242 use desiccants such as activated alumina and silica gel to absorb water molecules.
  • First capillary tube 251 meters liquid refrigerant 172 to evaporator 110.
  • Capillary tubes are long tube with very small diameter ( ⁇ 0.1mm); they are cost effective in maintaining the pressure difference (i.e. decompression of liquid refrigerant) required for the vaporization process in evaporator 110.
  • An expansion valve may be used to replace said capillary tube for systems with higher flow rate.
  • Evaporator 110 serves as a heat exchanger wherein vaporized refrigerant 171 having a negative density change absorbs heat. Through the process of thermal conduction, the temperature of the outside surfaces of evaporator 110 falls accordingly. Thermal convection currents generated by air extractor 160 supplies the necessary heat to said outside surfaces of the evaporator.
  • Evaporator 110 of the present application comprises typically tens of rows of coil configured to optimize air circulation, velocity and distribution of air on the surfaces and over the coil for maximum rate of extraction of water vapor in the ambient air.
  • the speed of airflow generated by air extractor 160 is one of the parameters used in said optimization process. Excessive air flow may hamper the removal of water from the air.
  • Controller device attains a predetermined air flow by adjusting the fan speed of air extractor 160. For the present mode of operation, controller device sets the fan speed of air extractor 160 to low or medium.
  • the cold gaseous refrigerant leaves evaporator 110 and returns to said external refrigerant source 210 via fluid return duct 228.
  • the air immediately surrounding the outer surfaces of evaporator 110 is saturated with water.
  • Water droplets condensed on the cold evaporator surfaces drip onto water droplets collection tray 270 and are directed to internal water storage tank 140.
  • Internal water level measurement means 272 measures the water level in said water storage tank 140 in a resolution determined by the number of sensors incorporated. It represents the basic configuration when only two float switches are used to detect a predetermined high (WLHI) and low (WL LO ) water levels.
  • said water purifier 271 is activated by controller device 280 on either a continuous or regular basis with said purifier being periodically activated for a first duration of tpuRE,, O N and deactivated for a second duration of tpuRE,,oFF-
  • the water purifier preferably comprises an ozone generator and an ultra-violet light. Illuminating ozone-treated drinking water with ultra-violet light provides a very effective means of purifying water. Ultra-violet light means produces light radiation of short wavelength at low cost. Ultra-violet light has been found to be a cost-effective means of destroying bacterial and viral infestations in drinking water.
  • Ozone is active oxygen capable of disinfecting water by means of oxidation. It has neutral alkalinity and is well- suited for destroying microbes such as bacteria, viruses, spores and algae, and removing contaminants and improving taste of drinking water.
  • ozone gas concentrations of 0.5ppm is used. Ozone oxidizes metals such as iron and manganese to form precipitation rapidly and efficiently, and it oxidizes nitrite ions to form nitrate ions which are stable and soluble, and ozone is very effective in removing hydrogen sulphide.
  • Said water purifier 271 may incorporate other filtration means including any mechanical, chemical and biological filtering systems suitable for purifying drinking water.
  • controller device 280 activates fluid pump 273 to transfer water from internal water storage tank 140 to external appliances or storage tanks via said fifth fluid duct 225.
  • Measured and control data can be logged, analyzed and displayed, or it can be coupled to an external computer via a wired or wireless data exchange interface 285.
  • Said measured and control data includes temperature, relative humidity, water level readings against time; total duration of operation, amount of water collected, fan speed, state of water purifier.
  • Controller device 280 selects a second mode of operation denoted by COOL when (a) the ambient temperature measured by said temperature measurement means 290 falls below said first predetermined threshold T LOI and said measured ambient temperature is equal to or greater than a second predetermined threshold TW, (b) the ambient relative humidity measured by relative humidity measurement means 291 is equal to or greater than said predetermined level RH LO and (c) the water level detected by internal water level measurement means 272 does not exceed a predetermined level WL HI .
  • controller device 280 operates the atmospheric water generation system through the same control and decision-making steps as used for mode NORMAL, in particular said first actuator valve 231 opens and second actuator valve 232 closes such that air pre-conditioning means 215 remains bypassed or deactivated.
  • the only exception is that the fan speed of air extractor 160 is set to high for increasing the air circulation 161 in the vicinity of evaporator 110, this leads to higher evaporation and condensation efficiency.
  • Controller device 280 selects a third mode of operation denoted by COLD when (a) the ambient temperature measured by said temperature measurement means 290 falls below said second predetermined threshold T LO2 and said measured ambient temperature is equal to or greater than a third predetermined threshold T LO3 , (b) the ambient relative humidity measured by relative humidity measurement means 291 is equal to or greater than said predetermined level RH LO and (c) the water level detected by internal water level measurement means 272 does not exceed a predetermined level WL H I. If the above conditions are met, controller device 280 operates the atmospheric water generation system through the same control and decision-making steps as used for mode NORMAL, with the exception that said second actuator valve 232 opens and said third actuator valve 233 closes.
  • the surface temperature of said air pre-conditioning means typically reaches 4O 0 C - 5O 0 C, capable of warming up the convection currents at evaporator 110.
  • Said convection currents are filtered ambient air drawn inside said water generation compartment 260 by said air extractor 160.
  • the fan speed of said air extractor 160 is set to medium to high. As a result, the average ambient temperature around the surfaces of evaporator 110 rises and the corresponding dew point temperature rises accordingly.
  • condensation occurs at a higher surface temperature of said evaporator 110, and less energy is required to initiate the condensation process. Consequently, the overall efficiency of water vapor extraction increases.
  • Second fluid dryer 242 absorbs any moisture present in the refrigerant and second capillary tube 252 provides the necessary change in refrigerant pressure and density.
  • Controller device 280 selects a fourth mode of operation denoted by
  • controller device 280 stops all the steps in the water generation processes, and particularly said first and second actuator valves close. However, said controller device 280 may continue to monitor ambient temperature, relative humidity and internal water level with said temperature measurement means 290, relative humidity measurement means 291 and internal water level measurement means 272 respectively.
  • Controller device 280 selects a fifth mode of operation denoted by DRY when (a) water generation has been stopped either by an user or by controller device 280 and (b) the ambient relative humidity measured by relative humidity measurement means 291 is equal to or greater than a predetermined level RH HI .
  • controller device 280 operates the atmospheric water generation system through the same control and decision-making steps as used for mode SUSPEND, with the exception that both said second and third actuator valves 232, 233 open to allow warm refrigerant to flow into air pre-conditioning means 215 via said second branch fluid duct 222.
  • the warm refrigerant hence raises the surface temperature of said air pre-conditioning means 215 before it returns to said external refrigerant source 210 via said fourth branch fluid duct 224 and said return fluid duct 228.
  • the raised surface temperature of air pre-conditioning means in turn raises the ambient temperature and lowers the humidity inside said water generation compartment 260.
  • Controller device 280 may turn on air extractor 160 to assist in achieving the required optimum humidity inside water generation compartment 260.
  • FIG. 3 shows the operational flow of said atmospheric water generation system of the present invention.
  • controller device 280 samples data measured by temperature, relative humidity and internal water level detection means 290, 291, 272 at a predetermined regular interval.
  • controller device 280 determines in step 310 the appropriate mode of operation based on said acquired temperature, humidity and internal water level data.
  • Controller device 280 looks up the necessary control actions in steps 320 and 321.
  • control signals are then sent to actuator valves 231, 232, 233 and air extractor 160 according to said determined mode of operation.
  • the settings for said water purifier 271 and fluid pump 273 depend primarily on said internal and external water level readings.
  • T LOI 18 0 C
  • TL O 2 15 0 C
  • T LO3 12 0 C as temperature threshold values used for classification of modes of operation
  • the atmospheric water generation system of the present invention provides a solution to water generation without the need for extensive water distribution networks, hence the present solution is well-suited for both indoor, outdoor, fixed and mobile applications.
  • the present atmospheric water generation system rides on existing refrigeration and central air system to provide the necessary refrigerant compression and condensation capability.
  • the present system offers a cost-effective water making system with relatively low equipment, operational and maintenance costs.
  • the present atmospheric water generation system features extended operating temperature down to 12 0 C or even lower, which makes it well-suited for many indoor and outdoor, fixed and mobile applications in not only tropical regions, but also temperate areas with ambient temperature well below what conventional systems are designed to operate.
  • the present system incorporates an innovative air pre-conditioning means which preferably draws in hot refrigerant from an existing refrigerant source for enhancing water condensation efficiency at low temperatures, and for suppressing undesired growth of mold and algae on the surface of evaporator, water droplet collection tray and other systems housed in the water generation compartment.

Abstract

The atmospheric water generation system of the present invention is capable of extracting water from the atmosphere using refrigeration-based compression cycle and heat exchange between ambient air and gaseous refrigerant supplied by an existing refrigerant source, and having a dual-purposed air pre-conditioning means for boosting water condensation efficiency at low temperatures, and said air pre-conditioning means having a second purpose of suppressing the undesired growth of molds and algae when the ambient humidity is relatively high. In addition, the atmospheric water generation system comprising an evaporator, air extractor, internal water storage tank, means of removing water stored in said internal tank to external appliances and storage units, temperature, humidity and water level measurement means, fluid dryers, capillary tubes and actuator valves makes it cost effective and well-suited for fixed and mobile applications in both indoor and outdoor environments.

Description

SYSTEM AND METHOD FOR ATMOSPHERIC WATER GENERATION OVER
EXTENDED RANGE OF AMBIENT TEMPERATURES
Field of the Invention
[0001] The present invention relates to drinking water generation, and more particularly apparatus and method of atmospheric water vapor extraction system having an innovative dual-purposed air pre-conditioning means which makes the system well-suited in many indoor and outdoor, fixed and mobile applications in not only tropical regions, but also temperate areas with ambient temperatures well below what conventional systems are designed to operate.
Background of the Invention
[0002] Water widely exists in the atmosphere, on the Earth's surface and beneath the ground. However, the majority of fresh water suitable for drinking is locked up in ice and groundwater aquifers. It has been estimated that only three percents of the world's water is drinkable and out of which a fraction is available for use. There are typically two major problems associated with the supply of drinking water. Firstly, water sources are not evenly distributed and some geographical locations do not have ready access to fresh water. The problem is usually alleviated by means of reservoirs and water desalination wherein water molecules are separated from salts, ions, metals and other trace elements in salt water. Reverse osmosis is the most common separation technique used today for desalination. Whilst the effectiveness of these solutions has improved over the past decades, desalination plants nonetheless require relatively high level of capital investment and operational costs which could be prohibitive to many countries and communities. Rainfall takes place only during a limited period of the year and water stored in reservoirs is subject to evaporation loss and exposure to contaminants. The second problem is related to potable water distribution which requires significant resources to set up and maintain. Water piping networks have limited lifespan and they are the main cause for water leakage and contamination. Metal and concrete ducts are vulnerable to corrosion by inorganic acid and alkaline contaminants, whereas organic solvents present in soil and building materials can be absorbed by and permeated through plastic piping.
[0003] Commercial systems capable of extracting water from air have made it possible to supply drinkable water to individual locations without the need for tapping on a central water source via complex distribution networks. It is therefore an attractive alternative to the conventional ways of deriving and distributing water. In principle, these devices collect water droplets formed by condensation of air vapor on some cold surfaces of refrigeration means, which is similar to the disclosure in patents filed by Ehrlich in 1978 (US 4255937) and Reidy in 1992 (US 5203989). With the advent of more efficient refrigeration system, the cost of electricity needed for extracting a certain amount of water from the atmosphere can be lower than the price of a bottled water of the same volume, and said cost is approaching the utility charge of an equivalent amount of water from the tap and the additional cost for boiling or purifying water using mechanical and chemical filtering means. However, the cost of hardware of a standalone atmospheric water generation device comprising compressor, condenser, evaporator and filtration means remains relatively high, and this leads to unattractive return of investment. In addition, for climates with low ambient temperature levels or in localities where temperature fluctuates significantly, atmospheric water extraction becomes difficult. Typically, these refrigeration-based systems for water vapor extraction operate above 180C - 2O0C. [0004] Katsumi and Han teach in their respective patents JP63328215 and
US5435151 water making apparatus for use on vehicles. Engel et al. discloses in patent application US 20040040322 a similar water extraction device for vehicles, together with some applications including central air system and mobile unit. All the disclosed devices tap on existing or external air conditioning systems to simplify system design and lower device cost. However, none of the disclosure has addressed the aforesaid limitation of operating temperature range associated with atmospheric water extraction. Conventional designs fail to function properly in many temperate areas where ambient temperature can readily drop below 2O0C at nights or during cold spells and storms, and this problem accentuates for mobile systems installed on vessels and ships, on caravans and emergency vehicles.
[0005] Accordingly, there is an imperative need for an atmospheric water extraction system capable of supplying water in tropical and temperate regions. The atmospheric water generation system of the present invention satisfies the need. Other advantages of this invention are apparent with reference to the detailed description provided herewith.
Summary of the Invention
[0006] The atmospheric water generation system of the present invention provides a solution to water generation without the need for extensive water distribution networks, the system rides on existing refrigeration and central air systems to provide the necessary refrigerant compression and condensation capability. Thus, the present system offers a cost-effective water making solution suitable for fixed and mobile units used in both indoor and outdoor environments.
[0007] In accordance with an aspect of the present invention, said atmospheric water generation system comprises an evaporator, air filter and extractor, internal water storage tank, means of removing water stored in said internal tank to external appliances and storage units, temperature, humidity and water level measurement means, fluid dryers, capillary tubes, actuator valves together with an air pre-conditioning means for conditioning convection currents to boost water extraction efficiency at lower ambient temperatures. Thus, the present system is well suited for temperate areas with ambient temperatures well below what conventional systems are designed to operate. The air preconditioning means of the present system is also designed to suppress the undesired growth of mold and algae on the surfaces of the evaporator, water droplet collection tray and other systems housed in the water generation compartment. Furthermore, the hot fluid used by the air pre-conditioning means is preferably supplied by the existing refrigerant source, hence the set-up and operational costs of said air pre-conditioning means is relatively low. Finally the system completes with a controller device capable of determining an appropriate mode of operation in accordance with measured temperature, humidity and water level data, and said controller device controls and powers all parts and subsystems, logs, stores, analyses and displays measured and control data.
[0008] In accordance with another aspect of the present invention, a method of extracting water from the atmosphere using refrigeration-based compression cycle and heat exchange between ambient air and gaseous refrigerant supplied by an existing refrigerant source, and having a dual-purposed air pre-conditioning means is disclosed. Brief Description of the Drawings
[0009] Preferred embodiments according to the present invention will now be described with reference to the Figures, in which like reference numerals denote like elements.
[0010] FIG. 1 illustrates a typical standalone atmospheric water extraction system available commercially (prior art). [0011] FIG. 2 illustrates the functional block diagram of the atmospheric water extraction system of the present invention.
[0012] FIG. 3 shows the operational flow of said atmospheric water generation system.
Detailed Description of the Invention
[0013] The present invention may be understood more readily by reference to the following detailed description of certain embodiments of the invention. [0014] FIG. 1 illustrates a typical standalone atmospheric water extraction system available commercially. The system employs a fluid refrigerant 171, 172, 173 to transfer heat out of an evaporator 110 such that the temperature on said evaporator surfaces is sufficiently low for condensation to take place. Cold gaseous refrigerant 171 flows into a compressor 120 which pressurizes the fluid and as a result, said refrigerant becomes hotter and changes state from gas to liquid. A condenser 130 is used to radiate or reject the heat built up in hot refrigerant 172. Subsequently, the partially cooled refrigerant 173 flows into said evaporator 110 through a small aperture (not shown). The pressure of said liquid refrigerant 173 drops and evaporates into gas which absorbs heat from the ambient air and objects. A fan 160 is used to improve air circulation 161 and evaporation efficiency. Water droplets 180 condensed on the surface of evaporator 110 are collected, treated with a filter 150 and stored in a tank 140 for consumption.
[0015] In an alternative design, the condenser 130 and compressor 120 are not parts of the system as refrigerant 173, 171 can be supplied from an existing refrigeration system. Said alternative system works according to the same compression cycle and thermal energy exchange between ambient air and refrigerant of said standalone system 100.
[0016] The required working temperatures for conventional water extraction systems are typically above 180C - 2O0C. Condensation occurs when a surface is cooler than the dew point temperature (condensation threshold temperature) of the air surrounding the surface. At this temperature, the air has a relative humidity equivalent to 100% and it becomes saturated with water. Said dew point temperature is dependent of both air temperature and humidity. A conventional water extraction system needs to achieve a threshold temperature of 40C on its evaporator surface when the ambient air has a temperature of 2O0C and relative humidity of 35%. This surface temperature requirement is excessive for many refrigeration systems, and frost may develop on said evaporator surfaces which could greatly dampen the efficiency of water extraction and even cause damages. Therefore conventional water extraction systems have limited use in many areas where ambient temperature stays or fluctuates to below 180C - 2O0C. It is not unusual for the ambient temperature to rise above 2O0C during the daytime when conventional water extraction systems function normally, and the temperature drops below 180C at nights or during cold spells and storms. This problem accentuates for systems operating in outdoor environment and non-built up areas, and for mobile systems installed on vessels and vehicles.
[0017] Water extraction efficiency generally improves with higher ambient temperature and / or relative humidity. When the air is damper than approximately 70% in relative humidity, mold and other fungi start to grow and colonize said evaporator 110 and other parts such as the drip tray typically employed in commercial water extraction systems. The undesirable growth of mold and fungi attracts dust and promotes excessive growth of harmful bacteria, which could severely undermine the air flow efficiency and water quality. This in turn results in higher operational and maintenance costs and longer downtimes.
[0018] The atmospheric water generation system of the present invention operates in conjunction with existing air conditioning and water storage systems to attain compact design, lower equipment and operational costs, and high level of flexibility in system design and integration. Standalone water extraction systems 100 typically employ basic refrigeration configurations as more advanced features such as variable frequency or inverter drive commonly used in today's air system is too costly to be incorporated into said standalone systems. This directly affects the overall efficiency of standalone systems in term of the amount of water generated per unit of input energy.
[0019] The water vapor condensation system of the present invention incorporates a novel dual-purposed air pre-conditioning means to warm up cold air flowing into its evaporator when the ambient temperature falls below a predetermined value in temperate areas, and said pre-conditioning means is also used to inhibit growth of fungi and bacteria when the present system is used in tropical zones. Said air pre-conditioning means is environment friendly as if relies primarily on hot fluid found in existing air conditioning systems.
[0020] FIG. 2 illustrates the functional block diagram of the atmospheric water extraction system of the present invention. Hot liquid refrigerant 172 is supplied by an external refrigeration system or refrigerant source 210 via a fluid inlet duct 220. Said hot refrigerant is typically tapped from the refrigerant outlet pipe of the condenser 130 (FIG. 1) of a refrigeration system. Said external refrigerant source 210 is typically an existing refrigeration or central air system of any type provided that said existing system 210 can supply sufficient amount of refrigerant to chill the surfaces of the evaporator 110 to a temperature below the corresponding dew point temperature. Said fluid inlet duct 220 further branches into first 221 and second 222 branch fluid ducts. Said first branch fluid duct 221 is in communication with a first actuator valve 231 which is connected in series with a first fluid dryer 241. The outlet of said first fluid dryer 241 is in communication with the inlet of a first capillary tube 251 having its outlet connected to the inlet of an evaporator 110. The outlet of said evaporator is in communication with a fluid return duct 228 which directs cold vaporized refrigerant 171 back to said external refrigerant source 210. Said second branch fluid duct 222 is in communication with a second actuator valve 232 having its outlet connected to the inlet of an air pre-conditioning means 215. The outlet of said air pre-conditioning means 215 branches into a third branch fluid duct 223 and a fourth branch fluid duct 224. Said third branch fluid duct 223 is in communication with a second fluid dryer 242 which is serially-connected to a second capillary tube 252 having its outlet connected to said inlet of said evaporator 110. Said fourth branch fluid duct 224 connects a third in-line actuator valve 233 to said fluid return duct 228. Said fluid return duct 228 is typically in communication with the inlet of the compressor 120 (FIG. 1) in said external refrigerant source 210. Said first and second actuator valves are typically solenoid valves which can be activated and disabled by a controller device 280. Check valves are preferably incorporated into said first and second actuator valves 231, 232 to prevent fluids in said first and second branch fluid ducts 221 & 222 from back- flowing into said external refrigerant source 210 via said fluid inlet duct 220 when said external refrigerant source is deactivated or when the pressure of said external refrigerant source system 210 has dropped excessively. Furthermore, said first and second capillary tubes 251, 252 can be replaced by expansion valves.
[0021] In addition to the ducting network disclosed above, the atmospheric water extraction system of the present invention comprises a water generation compartment 260 which houses said air pre-conditioning means 215, evaporator 110, and their associated parts and components which may include said second fluid dryer 242 and second capillary tube 252. In addition, said water generation compartment 260 has a first aperture 261. An air filter 218 is disposed in said first aperture 261 or in the vicinity of said first aperture. Furthermore, said compartment 260 has a second aperture 262 with an air extractor 160 disposed in said second aperture or in the vicinity of said second aperture. Said air filter 218 and air extractor 160 may be, as readily recognized by those skilled in the art, oriented in any way or disposed in any positions provided that they can operate to achieve effectively clean or dust-controlled air flow or circulation inside said water generation compartment 260. A water droplet collection tray 270 is disposed beneath said evaporator 110 and said collection tray 270 is housed inside said water generation compartment 260. Water droplets collected by said collection tray 270 is led out of said water generation compartment 260 and directed into an internal water storage tank 140 having a water purifier 271 and an internal water level measurement means 272. Said internal water level measurement means may be of the optical or float switch type. Said water purifier 271 preferably comprises an ultra violet light and an ozone generator. Said water purifier 271 may incorporate other filtration means including any mechanical, chemical or biological filtering systems suitable for purifying drinking water. A fifth fluid duct 225 leads the drinkable water stored in said internal water storage tank 140 to any external appliances or storage means by means of a fluid pump 273. Said controller device 280 electrically couples to said first, second and third actuator valves 231, 232 & 233, a temperature measurement means 290 and a relative humidity measurement means 291, said air extractor 160, internal water level measurement means 272 for detection of water level in internal water storage tank 140, external water level measurement means (not shown) for detection of water level in an external water storage unit, fluid pump 273, a standalone or integrated input means 281, a standalone or integrated display device 282, and any diagnosis data inputs for reporting malfunction or abnormal conditions of any parts including but not restricted to fluid pump 273, actuator valves 231 - 233, water purifier 271, air extractor 160, air pre-conditioning means 215 and evaporator 110. Said controller device 280 may couple to a signaling interface module for relaying any control signals required to operate said external refrigerant source 210, and any other electrically driven parts and components that require instructions, signaling and / or electricity supply. Said controller device 280 further comprises a processor for storing and executing software applications or embedded codes capable of generating appropriate control signals in accordance with a set of pre-programmed instructions. Measured data can be further processed in said controller device 280, and said processes include logging, reading and writing, storing and backing-up, analysis and displaying of measured and / or control data. Controller device 280 can be coupled to an external computer via a wired or wireless data exchange interface 285. Finally, the electrical power 286 supplied to said controller device 280 and the system as a whole may be single-phase or multi-phase alternating current or direct current or a combination of both alternating and direct currents tapped from power grids or mobile electricity generators such as those used on vessels, cruises, caravans, oil rigs, construction sites and other similar facilities. Rust resistance materials can be applied to the surfaces of the enclosure housing all the sub-systems, parts and components of the water generation system of the present invention when it is used on ships, cruises, oil rigs and the like. Finally, said air pre-conditioning means 215 together with second and third branch fluid ducts 221, 222, second and third actuator valves 232, 233, second fluid dryer 242 and capillary tube 252, can alternatively be implemented with an electrical heating element controlled and powered by said controller device 280.
[0022] Controller device 280 selects a first mode of operation denoted by
NORMAL when (a) the ambient temperature measured by said temperature measurement means 290 is equal to or greater than a first predetermined threshold TLOI, (b) the ambient relative humidity measured by relative humidity measurement means 291 is equal to or greater than a predetermined level RHLO and (c) the water level detected by internal water level measurement means 272 does not exceed a predetermined level WLHI- If the above conditions are met, controller device 280 opens first actuator valve 231 to allow liquid refrigerant 172 from external refrigerant source 210 to flow into said first branch fluid duct 221. Controller device 280 further shuts second actuator valve 232 and as a result, said liquid refrigerant 172 from said external refrigerant source bypasses air pre-conditioning means 215 and flows into evaporator 110 wherein refrigerant vaporizes and absorbs heat from the ambient air and objects. The state of third actuator valve 233 is immaterial. Moisture and contaminants present in first branch fluid duct 221 is absorbed by first fluid dryer 241. Moisture comes from sources such as trapped air and system leaks, and it can cause freeze-ups and corrosion of metallic components if not removed. Fluid dryers 241, 242 use desiccants such as activated alumina and silica gel to absorb water molecules. First capillary tube 251 meters liquid refrigerant 172 to evaporator 110. Capillary tubes are long tube with very small diameter (< 0.1mm); they are cost effective in maintaining the pressure difference (i.e. decompression of liquid refrigerant) required for the vaporization process in evaporator 110. An expansion valve may be used to replace said capillary tube for systems with higher flow rate. Evaporator 110 serves as a heat exchanger wherein vaporized refrigerant 171 having a negative density change absorbs heat. Through the process of thermal conduction, the temperature of the outside surfaces of evaporator 110 falls accordingly. Thermal convection currents generated by air extractor 160 supplies the necessary heat to said outside surfaces of the evaporator. When the temperature on the outside surfaces falls below the dew point temperature, water condensation takes place. The total required length of evaporator coil depends on the maximum water generation throughput said atmospheric water generation system 200 is designed for. Evaporator 110 of the present application comprises typically tens of rows of coil configured to optimize air circulation, velocity and distribution of air on the surfaces and over the coil for maximum rate of extraction of water vapor in the ambient air. The speed of airflow generated by air extractor 160 is one of the parameters used in said optimization process. Excessive air flow may hamper the removal of water from the air. Controller device attains a predetermined air flow by adjusting the fan speed of air extractor 160. For the present mode of operation, controller device sets the fan speed of air extractor 160 to low or medium. The cold gaseous refrigerant leaves evaporator 110 and returns to said external refrigerant source 210 via fluid return duct 228. The air immediately surrounding the outer surfaces of evaporator 110 is saturated with water. Water droplets condensed on the cold evaporator surfaces drip onto water droplets collection tray 270 and are directed to internal water storage tank 140. Internal water level measurement means 272 measures the water level in said water storage tank 140 in a resolution determined by the number of sensors incorporated. It represents the basic configuration when only two float switches are used to detect a predetermined high (WLHI) and low (WLLO) water levels. During normal operational condition and when water level detected by internal water level measurement means 272 exceeds a predetermined level WLLO, said water purifier 271 is activated by controller device 280 on either a continuous or regular basis with said purifier being periodically activated for a first duration of tpuRE,,ON and deactivated for a second duration of tpuRE,,oFF- The water purifier preferably comprises an ozone generator and an ultra-violet light. Illuminating ozone-treated drinking water with ultra-violet light provides a very effective means of purifying water. Ultra-violet light means produces light radiation of short wavelength at low cost. Ultra-violet light has been found to be a cost-effective means of destroying bacterial and viral infestations in drinking water. Ozone is active oxygen capable of disinfecting water by means of oxidation. It has neutral alkalinity and is well- suited for destroying microbes such as bacteria, viruses, spores and algae, and removing contaminants and improving taste of drinking water. In line with the World Health Organization, ozone gas concentrations of 0.5ppm is used. Ozone oxidizes metals such as iron and manganese to form precipitation rapidly and efficiently, and it oxidizes nitrite ions to form nitrate ions which are stable and soluble, and ozone is very effective in removing hydrogen sulphide. Said water purifier 271 may incorporate other filtration means including any mechanical, chemical and biological filtering systems suitable for purifying drinking water. If said external water storage tank is present and when said external water level measurement means (not shown) does not indicate full status, and said internal water level measurement means 272 indicates a water level higher than said predetermined low threshold WLLO, then controller device 280 activates fluid pump 273 to transfer water from internal water storage tank 140 to external appliances or storage tanks via said fifth fluid duct 225. Measured and control data can be logged, analyzed and displayed, or it can be coupled to an external computer via a wired or wireless data exchange interface 285. Said measured and control data includes temperature, relative humidity, water level readings against time; total duration of operation, amount of water collected, fan speed, state of water purifier.
[0023] Controller device 280 selects a second mode of operation denoted by COOL when (a) the ambient temperature measured by said temperature measurement means 290 falls below said first predetermined threshold TLOI and said measured ambient temperature is equal to or greater than a second predetermined threshold TW, (b) the ambient relative humidity measured by relative humidity measurement means 291 is equal to or greater than said predetermined level RHLO and (c) the water level detected by internal water level measurement means 272 does not exceed a predetermined level WLHI. If the above conditions are met, controller device 280 operates the atmospheric water generation system through the same control and decision-making steps as used for mode NORMAL, in particular said first actuator valve 231 opens and second actuator valve 232 closes such that air pre-conditioning means 215 remains bypassed or deactivated. The only exception is that the fan speed of air extractor 160 is set to high for increasing the air circulation 161 in the vicinity of evaporator 110, this leads to higher evaporation and condensation efficiency.
[0024] Controller device 280 selects a third mode of operation denoted by COLD when (a) the ambient temperature measured by said temperature measurement means 290 falls below said second predetermined threshold TLO2 and said measured ambient temperature is equal to or greater than a third predetermined threshold TLO3, (b) the ambient relative humidity measured by relative humidity measurement means 291 is equal to or greater than said predetermined level RHLO and (c) the water level detected by internal water level measurement means 272 does not exceed a predetermined level WLHI. If the above conditions are met, controller device 280 operates the atmospheric water generation system through the same control and decision-making steps as used for mode NORMAL, with the exception that said second actuator valve 232 opens and said third actuator valve 233 closes. A portion of the warm / hot refrigerant 172 from external refrigerant source 210 enters said air pre-conditioning means 215 via said second branch fluid duct 222. The surface temperature of said air pre-conditioning means typically reaches 4O0C - 5O0C, capable of warming up the convection currents at evaporator 110. Said convection currents are filtered ambient air drawn inside said water generation compartment 260 by said air extractor 160. The fan speed of said air extractor 160 is set to medium to high. As a result, the average ambient temperature around the surfaces of evaporator 110 rises and the corresponding dew point temperature rises accordingly. In other words, condensation occurs at a higher surface temperature of said evaporator 110, and less energy is required to initiate the condensation process. Consequently, the overall efficiency of water vapor extraction increases. As said third actuator valve 233 closes, refrigerant exiting said air pre-conditioning means flows through said second fluid dryer 242 and second capillary tube 252 before entering evaporator 110. Second fluid dryer 242 absorbs any moisture present in the refrigerant and second capillary tube 252 provides the necessary change in refrigerant pressure and density.
[0025] Controller device 280 selects a fourth mode of operation denoted by
SUSPEND when (a) the ambient temperature measured by said temperature measurement means 290 falls below said third predetermined threshold TLO3, or (b) the ambient relative humidity measured by relative humidity measurement means 291 is below said predetermined level RHLO or (c) the water level detected by internal water level measurement means 272 equals or exceeds a predetermined level WLHI- If the above conditions are met, controller device 280 stops all the steps in the water generation processes, and particularly said first and second actuator valves close. However, said controller device 280 may continue to monitor ambient temperature, relative humidity and internal water level with said temperature measurement means 290, relative humidity measurement means 291 and internal water level measurement means 272 respectively. Said controller device may further continue to activate water purifier 271 on said continuous or periodic basis if internal water level is above WLLO, and fluid pump 273 if internal water level is above WLLO and external water level is below the full status. [0026] Controller device 280 selects a fifth mode of operation denoted by DRY when (a) water generation has been stopped either by an user or by controller device 280 and (b) the ambient relative humidity measured by relative humidity measurement means 291 is equal to or greater than a predetermined level RHHI. If the above conditions are met, controller device 280 operates the atmospheric water generation system through the same control and decision-making steps as used for mode SUSPEND, with the exception that both said second and third actuator valves 232, 233 open to allow warm refrigerant to flow into air pre-conditioning means 215 via said second branch fluid duct 222. The warm refrigerant hence raises the surface temperature of said air pre-conditioning means 215 before it returns to said external refrigerant source 210 via said fourth branch fluid duct 224 and said return fluid duct 228. The raised surface temperature of air pre-conditioning means in turn raises the ambient temperature and lowers the humidity inside said water generation compartment 260. Typically, the growth of mold and algae slows down significantly below 75% to 80% in relative humidity. Controller device 280 may turn on air extractor 160 to assist in achieving the required optimum humidity inside water generation compartment 260.
[0027] FIG. 3 shows the operational flow of said atmospheric water generation system of the present invention. Upon activation of power supply to said system, controller device 280 samples data measured by temperature, relative humidity and internal water level detection means 290, 291, 272 at a predetermined regular interval. Next, controller device 280 determines in step 310 the appropriate mode of operation based on said acquired temperature, humidity and internal water level data. Controller device 280 then looks up the necessary control actions in steps 320 and 321. In step 330, control signals are then sent to actuator valves 231, 232, 233 and air extractor 160 according to said determined mode of operation. The settings for said water purifier 271 and fluid pump 273 depend primarily on said internal and external water level readings. [0028] The following parametric values have been used in a design employing the principle of the atmospheric water generation system of the present invention: TLOI = 180C, TLO2 = 150C and TLO3 = 120C as temperature threshold values used for classification of modes of operation; RHLO = 35% and RHm = 75% as relative humidity threshold values; tpuRE,0N = 10 minutes and tpuRE,OFF = 20 minutes for the periodic activation and cut- off durations.
[0029] The atmospheric water generation system of the present invention provides a solution to water generation without the need for extensive water distribution networks, hence the present solution is well-suited for both indoor, outdoor, fixed and mobile applications. The present atmospheric water generation system rides on existing refrigeration and central air system to provide the necessary refrigerant compression and condensation capability. Thus, the present system offers a cost-effective water making system with relatively low equipment, operational and maintenance costs. More importantly, the present atmospheric water generation system features extended operating temperature down to 120C or even lower, which makes it well-suited for many indoor and outdoor, fixed and mobile applications in not only tropical regions, but also temperate areas with ambient temperature well below what conventional systems are designed to operate. The present system incorporates an innovative air pre-conditioning means which preferably draws in hot refrigerant from an existing refrigerant source for enhancing water condensation efficiency at low temperatures, and for suppressing undesired growth of mold and algae on the surface of evaporator, water droplet collection tray and other systems housed in the water generation compartment.
[0030] While the present invention has been described with reference to particular embodiments, it will be understood that the embodiments are illustrative and that the invention scope is not so limited. Alternative embodiments of the present invention will become apparent to those having ordinary skill in the art to which the present invention pertains. Such alternate embodiments are considered to be encompassed within the spirit and scope of the present invention. Accordingly, the scope of the present invention is described by the appended claims and is supported by the foregoing description.

Claims

CLAIMSWhat is claimed is:
1. An atmospheric water generation system comprising: an evaporator receiving liquid refrigerant from an external refrigerant source via a first fluid path,. and returning vaporized refrigerant to said refrigerant source via a fluid return duct; an air pre-conditioning means being disposed in the vicinity of said evaporator for raising the ambient temperature of air and air currents surrounding said evaporator; an internal water storage tank for collecting water droplets condensed on the surfaces of said evaporator; a temperature measurement means and a humidity measurement means for measuring ambient air temperature and relative humidity respectively; and an internal water level measurement means for measuring the water level of said internal water storage means; and a controller device capable of controlling electrical parts and sub-systems of said atmospheric water generation system.
2. The atmospheric water generation system of claim 1, wherein said air preconditioning means receiving liquid refrigerant from said refrigerant source via a second fluid path, and the outlet of said air pre-conditioning means is in communication with said evaporator via a third fluid path and further in communication with said fluid return duct via a forth fluid path.
3 The atmospheric water generation system of claim 1, wherein an air filter and an air extractor being disposed in the vicinity of said evaporator and said air pre-conditioning means for generating convection air currents necessary for achieving sufficient water condensation on the surfaces of said evaporator;
4. The atmospheric water generation system of claim 1, wherein said external refrigerant source being any refrigeration or air conditioning system having at least one compressor capable of transforming vaporized or gaseous refrigerants to liquid state of higher temperature.
5. The atmospheric water generation system of claim 4, wherein said refrigeration or air conditioning system having been incorporated in an existing indoor or outdoor facility such as a building, a shelter, an oil rig and any means of transportation.
6. The atmospheric water generation system of claim 1, wherein said first fluid path comprising a first and second ends being in communication with said external refrigerant source and the inlet of said evaporator respectively, and a first actuator valve, a first fluid dryer and a first capillary tube or expansion valve being serially-connected from said first end to said second end.
7. The atmospheric water generation system of claim 6, wherein said first actuator valve allows uni-directional fluid flow from said external refrigerant source towards said evaporator.
8. The atmospheric water generation system of claim 2, wherein said second fluid path comprising a second actuator valve being connected between said external refrigerant source and the inlet of said air pre-conditioning means.
9. The atmospheric water generation system of claim 8, wherein said second actuator valve allows uni-directional fluid flow from said external refrigerant source towards said air pre-conditioning means.
10. The atmospheric water generation system of claim 2, wherein said third fluid path comprising a first and second ends being in communication with the outlet of said air preconditioning means and the inlet of said evaporator respectively, and a second fluid dryer and a second capillary tube or expansion valve being serially-connected from said first end to said second end.
11. The atmospheric water generation system of claim 2, wherein said fourth fluid path comprising a third actuator valve being connected between the outlet of said air preconditioning means and said fluid return duct.
12. The atmospheric water generation system of claim 1, wherein a water purifier being in contact with at least a portion of the stored water in said internal water storage tank, and said water purifier being capable of removing undesired contaminants, elements, bacteria, virsuses and any other undesired organisms present in said stored water.
13. The atmospheric water generation system of claim 12, wherein said water purifier including any combination of an ultra-violet light source and an ozone generator.
14. The atmospheric water generation system of claim 12, wherein said water purifier including any combination of any mechanical, chemical and biological filters suitable for purifying drinking water.
15. The atmospheric water generation system of claim 12, wherein said water purifier being activated continuously or periodically for a predetermined duration if the water level in said internal water storage tank being greater than a predetermined low threshold value denoted by WLL0.
16. The atmospheric water generation system of claim 1, wherein a fluid pump being used to transfer water from said internal water storage tank to any type of external water storage means.
17. The atmospheric water generation system of claim 16, wherein said fluid pump is deactivated if the water level in said internal water storage tank is less than or equal to said predetermined threshold value WLLO or when said external water storage means is not present or when the water level in said external water storage means exceeds a predetermined high threshold value.
18. The atmospheric water generation system of claim 1, wherein a water droplet collection tray being disposed beneath said evaporator for collecting water droplets condensed on the surfaces of said evaporator and directing said collected water droplets to said internal water storage tank.
19. The atmospheric water generation system of claims 3, 6, 8 and 11, wherein said first actuator valve opens, second and third actuator valves close, and the speed of said air extractor being relatively low to medium if said measured ambient temperature is equal to or greater than a first predetermined temperature threshold value TL01, and the measured relative humidity is equal to or greater than a predetermined relative humidity threshold value RHL0 and the measured water level of said internal water storage tank is less than a predetermined water level threshold value WLffl.
20. The atmospheric water generation system of claim 19, wherein said first actuator valve opens, second and third actuator valves close, and the speed of said air extractor being relatively high if said measured ambient temperature is less than said first temperature threshold TLO1 and said measured ambient temperature is equal to or greater than a second predetermined temperature threshold value TL02 where TL02 is less than TL01, and the measured relative humidity is equal to or greater than said threshold RHLO and the measured water level of said internal water storage tank is less than said threshold WLHI.
21. The atmospheric water generation system of claim 20, wherein said first and second actuator valves open, and said third actuator valve closes, and the speed of said air extractor being relatively medium to high if said measured ambient temperature is less than said second temperature threshold TLO2 and said measured ambient temperature is equal to or greater than a third predetermined temperature threshold value TLO3 where TL03 is less than TLO2, and the measured relative humidity is equal to or greater than said threshold RHL0 and the measured water level of said internal water storage tank is less than said threshold WLHI.
22. The atmospheric water generation system of claim 21, wherein said first, second and third actuator valves close, and said air extractor being deactivated if said measured ambient temperature is less than said third temperature threshold TL03, or the measured relative humidity is less than said threshold RH1x, or the measured water level of said internal water storage tank is equal to or greater than said threshold WI-111.
23. The atmospheric water generation system of claim 19, wherein said first actuator valve closes, said second and third actuator valves open, , and the speed of said air extractor being relatively low to medium if water generation has been disabled and said measured relative humidity is greater than a predetermined relative humidity threshold RHra with RHHI being greater than RHL0.
24. The atmospheric water generation system of claim 23, wherein said air extractor being deactivated.
25. The atmospheric water generation system of claim 1, wherein said air preconditioning means being an electrical heating means controlled by said controller device.
26. The atmospheric water generation system of claim 1, wherein said controller device comprising a processor capable of reading inputs from an integrated or a wireless input means; and logging, storing and analyzing measured data; displaying any measured and control data on an integrated or a remote display means; and monitoring for any malfunctions and abnormal conditions and any needs for part replacment of all subsystems.
27. A method for atmospheric water generation comprising the steps of: providing an evaporator for receiving liquid refrigerant from an external refrigerant source via a first fluid path, and returning vaporized refrigerant to said refrigerant source via a fluid return duct; disposing an air pre-conditioning means in the vicinity of said evaporator for raising the ambient temperature of air and air currents surrounding said evaporator; providing an internal water storage tank for collecting water droplets condensed on the surfaces of said evaporator; providing a temperature measurement means and a humidity measurement means for measuring ambient air temperature and relative humidity respectively; and an internal water level measurement means for measuring the water level of said internal water storage means; providing a controller device capable of controlling electrical parts and sub-systems of said atmospheric water generation system.
28. The method of claim 27, wherein said air pre-conditioning means receiving liquid refrigerant from said refrigerant source via a second fluid path, and the outlet of said air pre-conditioning means is in communication with said evaporator via a third fluid path and further in communication with said fluid return duct via a forth fluid path.
29. The method of claim 27, wherein an air filter and an air extractor being disposed in the vicinity of said evaporator and said air pre-conditioning means for generating convection air currents necessary for achieving sufficient water condensation on the surfaces of said evaporator;
30. The method of claim 27, wherein said external refrigerant source being any refrigeration or air conditioning system having at least one compressor capable of transforming vaporized or gaseous refrigerants to liquid state of higher temperature.
31. The method of claim 30, wherein said refrigeration or air conditioning system having been incorporated in an existing indoor or outdoor facility such as a building, a shelter, an oil rig and any means of transportation.
32. The method of claim 27, wherein said first fluid path comprising a first and second ends being in communication with said external refrigerant source and the inlet of said evaporator respectively, and a first actuator valve, a first fluid dryer and a first capillary tube or expansion valve being serially-connected from said first end to said second end.
33. The method of claim 32, wherein said first actuator valve allows uni-directional fluid flow from said external refrigerant source towards said evaporator.
34. The method of claim 28, wherein said second fluid path comprising a second actuator valve being connected between said external refrigerant source and the inlet of said air pre-conditioning means.
35. The method of claim 34, wherein said second actuator valve allows uni-directional fluid flow from said external refrigerant source towards said air pre-conditioning means.
36. The method of claim 28, wherein said third fluid path comprising a first and second ends being in communication with the outlet of said air pre-conditioning means and the inlet of said evaporator respectively, and a second fluid dryer and a second capillary tube or expansion valve being serially-connected from said first end to said second end.
37. The method of claim 28, wherein said fourth fluid path comprising a third actuator valve being connected between the outlet of said air pre-conditioning means and said fluid return duct.
38. The method of claim 27, wherein a water purifier being in contact with at least a portion of the stored water in said internal water storage tank, and said water purifier being capable of removing undesired contaminants, elements, bacteria, virsuses and any other undesired organisms present in said stored water.
39. The method of claim 38, wherein said water purifier including any combination of an ultra-violet light source and an ozone generator.
40. The method of claim 38, wherein said water purifier including any combination of any mechanical, chemical and biological filters suitable for purifying drinking water.
41. The method of claim 38, wherein said water purifier being activated continuously or periodically for a predetermined duration if the water level in said internal water storage tank being greater than a predetermined low threshold value denoted by WLL0.
42. The method of claim 27, wherein a fluid pump being used to transfer water from said internal water storage tank to any type of external water storage means.
43. The method of claim 42, wherein said fluid pump is deactivated if the water level in said internal water storage tank is less than or equal to said predetermined threshold value WL1x, or when said external water storage means is not present or when the water level in said external water storage means exceeds a predetermined high threshold value.
44. The method of claim 27, wherein a water droplet collection tray being disposed beneath said evaporator for collecting water droplets condensed on the surfaces of said evaporator and directing said collected water droplets to said internal water storage tank.
45. The method of claims 29, 32, 34 and 37, wherein said first actuator valve opens, second and third actuator valves close, and the speed of said air extractor being relatively low to medium if said measured ambient temperature is equal to or greater than a first predetermined temperature threshold value TL01, and the measured relative humidity is equal to or greater than a predetermined relative humidity threshold value RHLO and the measured water level of said internal water storage tank is less than a predetermined water level threshold value WL111.
46. The method of claim 45, wherein said first actuator valve opens, second and third actuator valves close, and the speed of said air extractor being relatively high if said measured ambient temperature is less than said first temperature threshold TLO1 and said measured ambient temperature is equal to or greater than a second predetermined temperature threshold value TLO2 where TLO2 is less than TL01, and the measured relative humidity is equal to or greater than said threshold RHL0 and the measured water level of said internal water storage tank is less than said threshold WL111.
47. The method of claim 46, wherein said first and second actuator valves open, and said third actuator valve closes, and the speed of said air extractor being relatively medium to high if said measured ambient temperature is less than said second temperature threshold TL02 and said measured ambient temperature is equal to or greater than a third predetermined temperature threshold value TL03 where TLO3 is less than TLO2, and the measured relative humidity is equal to or greater than said threshold RHLO and the measured water level of said internal water storage tank is less than said threshold WLHI.
48. The method of claim 47, wherein said first, second and third actuator valves close, and said air extractor being deactivated if said measured ambient temperature is less than said third temperature threshold TLO3, or the measured relative humidity is less than said threshold RHLO or the measured water level of said internal water storage tank is equal to or greater than said threshold WLH1.
49. The method of claim 45, wherein said first actuator valve closes, said second and third actuator valves open, , and the speed of said air extractor being relatively low to medium if water generation has been disabled and said measured relative humidity is greater than a predetermined relative humidity threshold RHHI with RHHI being greater than RHLO.
50. The method of claim 49, wherein said air extractor being deactivated.
51. The method of claim 27, wherein said air pre-conditioning means being an electrical heating means controlled by said controller device.
52. The method of claim 27, wherein said controller device comprising a processor capable of reading inputs from an integrated or a wireless input means; and logging, storing and analyzing measured data; displaying any measured and control data on an integrated or a remote display means; and monitoring for any malfunctions and abnormal conditions and any needs for part replacment of all subsystem.
PCT/SG2008/000061 2007-03-02 2008-02-25 System and method for atmospheric water generation over extended range of ambient temperatures WO2008108740A1 (en)

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