RU2081256C1 - Method for extracting water from air and device for implementing the same - Google Patents

Abstract

FIELD: water extraction from air, agriculture. SUBSTANCE: air flow is cooled on the section of artificial cooling. Heat transfer between "n" steps of the flow is carried out upstream and downstream from the section. So as the heat transfer is occurred from the first step to n-th step, from the second step to (n-1)-th step and so on, between n/2 step to n/2+1 step. On achieving dew point, steam is condensed in the steps. The device has a passage to transfer air flow. Cooling member of the cooler, heat exchanger and fan are placed in the passage. Heat exchanger is multi-sectional. Heat transfer members are placed on both sides of the cooling member. Heat flux of the first member is connected to the "n"-th member, the second one to (n-1)-th one, and so on. Member n/2 is connected to n/2+1 member. EFFECT: higher efficiency. 14 cl, 4 dwg

Description

 The invention relates to the field of gas thermodynamics, more specifically to the production of water from atmospheric air. namely, to a method for extracting water from air and a device for its implementation, and can be used in the field, agriculture and everyday life as an alternative source of fresh water.

 Currently, it is very urgent to obtain fresh water in the absence or inaccessibility of traditional sources of wells, wells, reservoirs, etc. especially in arid climates.

 One of the possible methods for solving the problem is the condensation of water contained in the air.

 So, known methods and devices for extracting water from atmospheric air, one of which is an air-water generator according to US patent N 5203989.

 According to this patent, a stream of air containing water vapor is formed, it is cooled to a temperature below the dew point, water vapor is condensed into water, and dehydrated air is released into the atmosphere.

 The known device comprises a housing in which a refrigeration machine and means for transporting an air stream are installed. The lower part of the housing is connected to a condensate collector.

 When pumping a stream of atmospheric air containing water vapor, they condense on the cooling element of the chiller and simultaneously cool the air stream that is released into the atmosphere.

 The known method and device are characterized by low cost-effectiveness of using the refrigeration capacity of the refrigeration machine, since only a small part of it is used to condense water vapor, especially at low humidity. Moreover, most of the cooling capacity is spent on cooling dehydrated air discharged into the atmosphere.

 A known method of extracting water from air (WO, patent 93/04764, 1993), which consists in forming a stream of air containing water vapor, performing an artificial cooling of the air stream in one section of the second stream, organizing heat transfer between the parts of the air stream located in both sides of the artificial cooling section condense water vapor in that part of the air stream whose temperature is below the dew point, and emit dehydrated air into the atmosphere.

 A device is known for extracting water from air (WO, patent 93/04764, 1993), containing a thermodynamic converter, in which there is a channel for transporting an air stream containing water vapor, in which there is a cooling element of the refrigeration machine, a heat exchanger and a fan, and a condensate collector communicated with part of the channel.

 In the known method, a single pre-cooling of the incoming air stream is carried out, which improves the efficiency of using the refrigerating capacity of the refrigeration machine.

 Structurally, the known device consists of two units, in one of which a heat exchanger is installed, and in the other a refrigeration machine. Both blocks are interconnected by gas pipelines, which transport the entire volume of air, which leads to large dimensions of the device, especially with high productivity.

 At the same time, the complex trajectory of the air flow creates a large gas-dynamic resistance.

 Despite the preliminary cooling of the incoming air flow, the efficiency of using the cooling capacity of the chiller is not high, since a significant part of the chilling capacity of the chiller is not used to condense water vapor, but to cool the air.

 The basis of the invention is to develop a method for extracting water from air and create a device for its implementation, which would achieve an increase in the efficiency of using the refrigeration capacity of the refrigeration machine and reduce the dimensions of the device.

 The problem is achieved in that in the method of extracting water from air, which consists in forming a stream of air containing water vapor, performing an artificial cooling of the air stream in one section of this stream, organizing heat transfer between the parts of the air stream located on both sides of the section of artificial cooling, water vapor is condensed in that part of the air stream whose temperature is below the dew point, and dehydrated air is released into the atmosphere, according to the invention, heat transfer is organized between n steps of the air flow, which are equally located before and after the artificial cooling section so that the heat transfer is carried out in the direction of the air flow from the first stage to the n-th, from the second to the (n-1) -th and then sequentially from the p / 2 stage to the step (n / 2 + 1).

 To increase the mass of condensed water, it is advisable that the temperature of the artificial cooling section is further lowered by performing indirect heat exchange between this section and dehydrated air after the nth stage.

 To increase the efficiency of heat transfer between n stages of the air flow, an intermediate coolant is used, which can be used as water.

 To prevent freezing of water, a substance is added to it to reduce the freezing temperature.

 It is advisable as a substance that reduces the freezing point of water, use ethyl alcohol or sodium chloride.

 The problem is also solved by the fact that in a device for extracting water from air containing a thermodynamic converter, in which there is a channel for transporting an air stream containing water vapor, in which a cooling element of the refrigeration machine, a heat exchanger and a fan, and a condensate collector in communication with part of the channel, according to the invention, the heat exchanger is multi-sectional, each section of which consists of a pair of heat transfer elements, the total number of which is n, while the heat insulators They are one from the other and in each section are located on both sides of the cooling element and are interconnected by the heat flux so that, in order of location, the first heat transfer element is connected to the nth, the second to the (n-1) th and then sequentially heat transfer element n / 2 with heat transfer element (n / 2 + 1).

 The device may use a compression chiller or a chiller based on the Peltier phenomenon. The heat-loaded element of the chiller, in the first case a condenser, and in the second block of hot junctions, are located at the outlet of the channel after the nth heat transfer element.

 To increase the mass of air cooling the heat element of the refrigeration machine, and improve the operation of the refrigeration machine, it is advisable to make holes in the channel after the n-th heat transfer element to suck in atmospheric air.

 To increase the efficiency of heat transfer, it is advantageous to use an intermediate heat carrier, while it is advisable to connect each pair of heat transfer elements to each other by two pipelines and provide a pump installed on one of them, providing circulation of the intermediate heat carrier.

 It is structurally advantageous to install the pumps on a common shaft.

 For the most complete collection of condensed water vapor, the condensate collector is communicated with that part of the channel in which the heat transfer elements from the first to (n / 2 + 1) are located.

 The proposed method and device for extracting water from air due to the organization of a multi-stage heat exchange process between the inlet and outlet parts of the air stream provides a discrete decrease in the air temperature to the cooling element and the same temperature increase after this element, providing at the outlet of the device an air flow temperature close to atmospheric .

 In the process of multi-stage heat exchange, a deeper cooling of the air in the area of moisture condensation is provided at the same cooling capacity of the chiller, which allows a more complete process of extracting water from the air and increase the productivity of the device.

 The proposed structural solution of the heat exchanger, namely, the separation of the heat exchanger into pairs of heat transfer elements, allows you to organize the air flow with the lowest gas-dynamic resistance.

 For an even greater increase in cooling capacity and taking into account the fact that the air temperature at the outlet of the device is always lower than the temperature of the air at its inlet, the exhaust air is used to cool the heat-loaded elements of the refrigeration machine.

 At the same time, the cooling capacity of the chiller increases and the energy consumed by the installation is used more efficiently.

 The use of a liquid, in particular water, as a heat carrier allows one to reduce the dimensions of the device, and the introduction of additives into a liquid heat carrier excludes the possibility of water freezing in the heat exchanger.

 The constructive combination of pumps on a common shaft allows the use of one electric motor, which allows for smooth control of the flow rate of the pumped liquid and to reduce the dimensions of the device.

 The invention is illustrated by a description of specific embodiments thereof and the accompanying drawings, where in FIG. 1 schematically shows the process of extracting water from air, accompanied by a diagram of changes in air temperature along the length of the channel: in FIG. 2 diagram of a device for extracting water from air; in FIG. 3 another embodiment of the device of FIG. 2; in FIG. 4 plots of the condensed water mass versus atmospheric air temperature.

The method of extracting water from air is that they form a stream 1 (Fig. 1) of atmospheric air containing water vapor, which is passed through a system of n heat transfer stages 2 ₁ , 2 ₂ , 2 _n , located in series along stream 1.

 In the middle part between the steps n / 2 and (n / 2 + 1) is located section 3 of artificial cooling. When the air stream 1 passes through section 3, the temperature decreases behind it, and conditions arise for heat exchange between the parts of the air stream 1 located before and after this section 3.

 In the described method, heat transfer is carried out by heat transfer in pairs from the first stage to the n-th, from the second to the (n-1) -th and then sequentially from the stage n / 2 to the stage (n / 2 + 1).

Moreover, each pair of steps leads to a decrease in the temperature of the air stream 1 at the location of the artificial cooling section 3. If in section 3 the temperature of air flow 1 decreases by ΔT _c , then, without taking into account the condensation phenomenon, the temperature of incoming air T _at can be reduced to T _min = ΔT _c (n / 2 + 1).

Thus, at each stage 2 ₁ , 2 ₂ , 2 _{n / 2} , a discrete decrease in the flow temperature by ΔT occurs, and at steps 2 _{n / 1 + 1} .2 _n, the temperature rises.

In this case, the temperature T _at will always be higher than the temperature T _{n of the} outlet stream by ΔT ₁ the temperature difference provided by the first stage 2 ₁ .

In the part of the air stream containing water vapor (randomly arranged points shown in the drawing), due to cooling, the temperature T _{dp of} the dew point is reached, after which the process of moisture condensation, conditionally shown as drops, begins.

For dry air, ΔT will be maximum ΔT _max . For humid air, condensation of water vapor results in the release of thermal energy in each stage. The value of ΔT in each stage will be less than ΔT _max and depends on the amount of condensed water.

Since the total temperature range is between T _at and О ^o С, an increase in the number of steps leads to a decrease in the temperature difference ΔT in each step and, as a result, to a decrease in the temperature difference between atmospheric and dehydrated air at the outlet T _at - T _n .

конденсируемой воды за единицу времени:

где Р_c холодопроизводительность,
m_at- расход воздуха,
C_p теплоемкость воздуха, Q теплота конденсации воды.For a better understanding of the benefits of multi-stage heat transfer, the following formula is used to determine the mass

condensed water per unit time:

where P _c cooling capacity,
m _at - air consumption,
C _{p is the} heat capacity of air; Q is the heat of condensation of water.

тем больше, чем больше холодопроизводительность и чем меньше разность температур между Т_at и Т_n.From the formula it follows that the amount of water

the greater, the greater the cooling capacity and the smaller the temperature difference between T _at and T _n .

 Referring to FIG. 1, a graph of temperature changes along the flow length illustrates the course of heat exchange processes and the condensation process.

Condensation begins at that point in stream 1, where its temperature drops below the temperature T _{dp of} the dew point and continues to the stage (n / 2 + 1) following section 3. The flow interval Δl denotes the condensation section. The left boundary of this section Δl can shift along the length of the flow left and right, depending on the humidity of the atmospheric air.

At 100% humidity, the beginning of the left boundary of the Δl section coincides with the first stage 2 ₁ .

As follows from FIG. 1, the temperature T _{n is} less than the temperature T _at . Typically, any chiller has a heat-loaded chilled element, the temperature of which determines the cooling capacity of the chiller. The use of air cooler than atmospheric for cooling this element increases the cooling capacity and indirectly lowers the temperature difference Δl _c in section 3, which allows to increase the selection of moisture from the air.

 In the drawing, arrows A show the direction of movement of the air stream 1, and arrows in the direction of heat flows during heat transfer between the steps of the air stream 1.

 The heat transfer between the steps can be carried out directly by the parts of the air flow (similar to that described in patent WO 93104764), and can be implemented using an intermediate, more efficient than a gas coolant.

 Water is usually used as an intermediate coolant, and to prevent its freezing, substances are added that reduce the freezing temperature of water, and taking into account the possible ingress of these substances into condensed water, they should be non-toxic.

 It is economical and safe to use, for example, ethyl alcohol or sodium chloride.

 After passing through section 3 of artificial cooling, the amount of moisture in the air decreases sharply, and this air can be considered dehydrated, then this air is discharged into the atmosphere.

 A device for extracting water from air contains a thermodynamic transducer in which there is a channel 4 (Fig. 2) for transporting a stream of air containing water vapor. In the channel 4 are located the cooling element 5 of the refrigeration machine, the heat exchanger 6 and the fan 7.

The heat exchanger 6 is multi-sectional, each section of which consists of a pair of heat transfer elements, the total number of which is n. The heat transfer elements 8 ₁ , 8 ₂ , 8 _{n are} thermally insulated from each other and in each section are located on both sides of the cooling element 5 and are interconnected by heat flow so that in order of location element 8 ₁ is connected to element 8 _n , element 8 ₂ - with element 8 _n-1 and then sequentially element 8 _{n / 2} with element 8 _{n / 2 + 1} .

 With this embodiment of the heat exchanger 6, a straight-line transportation of the air flow is provided, which reduces the gas-dynamic resistance.

 In the described embodiment of the device, it is advisable to use a liquid-air heat exchanger, which makes the device more compact compared to the heat exchanger used in patent WO 93/04764.

Heat transfer elements 8 ₁ , 8 ₂ . 8 _n sections of the heat exchanger 6 may be a radiator with a developed heat transfer surface, for example, a heat exchanger from an air conditioner.

With the part of the channel 4, in which the heat transfer elements from 8 ₁ to 8 _{n / 2 + 1 are located} , a condensate collector 9 is communicated.

 In another embodiment (Fig. 3) of the inventive device, an intermediate coolant is used, for the circulation of which within each section the heat transfer elements are communicated by two pipelines 10, one of which has a pump 11. In addition, in the described embodiment of the device, in the outlet part of the channel 4 after heat transfer element 8 has holes 12 for suction of atmospheric air.

 The device can be used refrigeration machine as a compression type, and a machine based on the Peltier phenomenon.

 In the first case, a capacitor is placed at the outlet of the channel 4, and in the second block of hot junctions of the refrigeration machine.

 In this case, the cooling element 5 is an evaporator or a block of cold junctions, each of which is connected by pipelines through a compressor or wires through a rectifier, respectively, to a condenser or a block of hot junctions (due to the conventional image of the chiller, the condenser and the block of hot junctions are assigned position 13, and the compressor or rectifier position 14).

 Structurally, it is advisable to place all the pumps 11 on a common shaft 15 and provide with one electric motor 16.

 The device operates as follows.

 Turn on the fan 7 (Fig. 2), which directs the flow of atmospheric air containing water vapor into the channel 4, and drive the refrigeration machine.

 When the air stream reaches the cooling element 5, its temperature decreases so much that heat exchange between the parts of the air stream before and after the cooling element 5 is possible.

 Heat transfer occurs as described above in the description of the method, as illustrated in FIG. one.

Thus, the air flow reaches the cooling element 5, having a temperature below the temperature T _{dp of} the dew point. From the place of channel 4, where T _dp is reached, to the element 8 _{n / 2 + 1} , the process of condensation of water vapor proceeds.

Moisture collects in condensate collector 9. Dehydrated cold air passes through the heat transfer elements 8 _{n / 2 + 1} -8 _n , as a result of which due to the existence of a connection through heat fluxes, preliminary stepwise cooling of the air occurs in the first part of channel 4.

When the atmospheric humidity is close to 100%, the dew point temperature T _dp can be reached immediately after the first heat transfer element 8 ₁ , therefore, the condensate collector 9 is placed under the heat transfer elements from 8 ₁ to 8 _{n / 2 + 1} .

After passing the last section 8 _n, dehydrated air is released into the atmosphere.
The embodiment of the device shown in FIG. 3 basically functions similarly to that described above.

 The differences are that the cooled dehydrated air blows around the condenser 13 or block 13 hot junctions, lowering its temperature and increasing the cooling capacity of the refrigeration machine. In this case, the temperature of the cooling element 5 (the evaporator or the block of cold junctions) decreases, increasing the amount of condensed moisture.

 The flow of atmospheric air passing through the openings 12 increases the mass of air cooling the condenser 13 or block 13 hot junctions and improves the operation of the refrigeration machine.

 Thus, the present invention allows, due to multi-stage heat transfer, to increase the mass of condensate obtained, that is, it is more efficient to use the cooling capacity of the refrigeration machine.

 For a better understanding of the invention, the following is a concrete example.

The device contained six heat transfer elements, the air flow rate was not more than 0.4 m ₃ / s, which was regulated during operation.

 We used an air-cooled compression chiller with a cooling capacity of 5500W.

от температуры Т_at атмосферного воздуха для разной влажности воздуха (от 40 до 100%). Кривые имеют участки, полого спадающие по мере уменьшения Т_at и резко спадающие до О^oС. Положение точки излома для каждой кривой определяется величиной предельного расхода воздуха 0,4 м³/с.FIG. 4 shows the dependence of the mass of condensate

temperature T _at atmospheric air for different air humidity (from 40 to 100%). The curves have sections that slope slightly with decreasing T _at and sharply drop to O ^o C. The position of the break point for each curve is determined by the limit air flow rate of 0.4 m ³ / s.

 As you can see, the higher the humidity of the atmospheric air and the higher the temperature, the more water can be extracted from the air.

Claims (14)

 1. The method of extracting water from air, which consists in forming a stream of air containing water vapor, performing an artificial cooling of the air stream in one section of this stream, organizing heat transfer between the parts of the air stream located on both sides of the artificial cooling section, condensing the vapor water in that part of the air stream, the temperature of which is below the dew point, and emit dehydrated air into the atmosphere, characterized in that the heat transfer is organized between n steps of the air flow, which are believed equally before and after the portion of refrigeration so that the heat transfer is carried out on the air flow direction from the first stage to the n-th, from the second to (n 1) th and further successively from stage n / 2 stages to n / 2 + 1.  2. The method according to p. 1, characterized in that it further lowers the temperature of the section of artificial cooling by performing indirect heat exchange between this section and dehydrated air after the n-th stage.  3. The method according to p. 1, characterized in that the heat transfer between n steps of the air flow is carried out by means of an intermediate coolant.  4. The method according to p. 3, characterized in that water is used as an intermediate heat carrier.  5. The method according to p. 4, characterized in that a substance is added to the water to lower the freezing point of water.  6. The method according to p. 5, characterized in that as a substance that reduces the freezing point of water, ethanol is used.  7. The method according to p. 5, characterized in that as a substance that reduces the freezing point of water, use sodium chloride.  8. A device for extracting water from air, containing a thermodynamic converter, in which there is a channel for transporting an air stream containing water vapor, in which there is a cooling element of the chiller, a heat exchanger and a fan, and a condensate collector in communication with a part of the channel, characterized in that the heat exchanger is multi-sectional, each section of which consists of a pair of heat transfer elements, the total number of which is n, while the heat transfer elements are thermally insulated from one another and in each section are located on both sides of the cooling element and are interconnected along the heat flux so that in order of location the first heat transfer element is connected with the nth, the second with the (n 1) m and then sequentially the heat transfer element n / 2 s heat transfer element n / 2 + 1.  9. The device according to p. 8, characterized in that when using a compression refrigeration machine, its condenser is located at the outlet of the channel after the nth heat transfer element.  10. The device according to p. 8, characterized in that when using a refrigeration machine based on the Peltier phenomenon, its block of hot junctions is located at the outlet of the channel after the nth heat transfer element.  11. The device according to p. 9 or 10, characterized in that in the channel after the nth heat transfer element, openings are made for suction of atmospheric air.  12. The device according to p. 8, characterized in that each pair of heat transfer elements of one section is connected by two pipelines and equipped with a pump installed on one of them for circulation of the intermediate coolant.  13. The device according to p. 12, characterized in that the pumps are mounted on a common shaft.  14. The device according to paragraphs. 8 13, characterized in that the condensate collector is in communication with that part of the channel in which the heat transfer elements from the first to n / 2 + 1 are located.

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