• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention describes an adiabatic absorber (1) for an absorption machine, comprising: a first channel (2a) for a vapor phase refrigerant; a second channel (2b) for a vapor phase refrigerant; and a plurality of microchannels (3) for a liquid phase solution separated from each other by thin (4) walls and enclosed between the first channel (2a) and the second channel (2b) in such a way that a pair of microporous membranes (5). ) are interposed between the plurality of microchannels (3) and the respective first channel (2a) and second channel (2b). The microporous membranes (5) are configured to let the refrigerant pass in the vapor phase but to prevent the passage of the solution in the liquid phase. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2647967A1
    申请号:ES201630682
    申请日:2016-05-26
    公开日:2017-12-27
    发明作者:María Del Carmen VENEGAS BERNAL；Mercedes DE VEGA BLÁZQUEZ；Néstor GARCÍA HERNANDO；Ulpiano RUIZ-RIVAS HERNANDO
    申请人:Universidad Carlos III de Madrid；
    IPC主号:
    专利说明:

    Adiabatic Absorber for Absorption Machine
    OBJECT OF THE INVENTION
    The present invention belongs in general to the field of thermodynamics, and more specifically to the devices used for the implementation of absorption cycles.
    The object of the present invention is a novel absorber for an absorption machine that has a higher efficiency and a smaller size compared to conventionally used absorbers.
    BACKGROUND OF THE INVENTION
    Absorption machines are cyclic thermal machines that pump heat from a heat source to a higher temperature heat sink. These are very useful energy machines to be able to recover residual heats or use renewable heat, such as geothermal, or heat obtained from solar radiation through solar thermal collectors. The absorption machines base their operation on the affinity of certain substances (solvents) of high evaporation temperature by other substances (refrigerants) that change phase at the temperatures of interest. Thus a solution of the refrigerant in the solvent is formed inside the machine. However, although they have been in existence for more than a century, absorption machines lack the enormous diffusion of mechanical compression heat pumps mainly due to their greater weight and volume.
    In its simplest design, called simple effect, its basic operation is described below with reference to Fig. 1. First, in a generator (G) an activation heat (Q'in) is applied to a solution of the refrigerant in the solvent. As a consequence, the more volatile refrigerant vapor separates from the rest of the solution and leaves the generator (G) until it reaches the point (P2) at the inlet of a condenser (C), while the rest of the solution leaves the generator (G) as a concentrated solution of refrigerant and solvent. Then, the refrigerant vapor condenses at high pressure due to the evacuation of heat to an external high temperature sump carried out in a condenser (C), reaching the point (P3). The evacuated heat (QOUI) constitutes part or all of the useful effect when the machine acts exclusively as a heat pump of heat effect. The liquid refrigerant is then expanded in an expansion valve (EV) to reach point (P4) at a lower pressure, and then evaporated at low pressure in an evaporator (E). In the evaporator (E) there is a heat absorption (Oin) of an external focus at low temperature, achieving the cooling effect of the absorption machine when it is configured as a cooling heat pump. When it leaves the evaporator (E), the vapor phase refrigerant reaches the point (P1) before entering an absorber (A). For its part, the concentrated solution of refrigerant and solvent leaving the generator (G) passes through a valve (V) to lower its pressure to the pressure of the absorber (A). The absorption of the refrigerant in the vapor phase in the solvent in the liquid phase then occurs, evacuating a heat (0'00 ') that constitutes part or all of the useful effect when the machine is configured as calorific
    or it is evacuated to the environment, along with the heat of condensation, if the machine is configured as a refrigerator. The outlet of the absorber (A) is a diluted solution of refrigerant and solvent that is pumped through a pump (B) to return it to the generator
    (G) And start the cycle again.
    In short, the main function of the absorber of an absorption machine is to achieve the absorption of the refrigerant in the solvent. Currently, the absorbers used are usually based on heat exchangers of the casing type and tubes with simultaneous heat extraction. More specifically, these types of absorbers are based on contacting the vapor phase refrigerant with the liquid phase solution inside a housing. For this, the solution is sprayed from the top of the housing, while steam is introduced through different areas depending on the configuration. To increase the absorption performance, low temperature pipes are arranged horizontally inside the housing, so that most of the absorption has Play on said tube surface. To keep the tubes at a low temperature, a second fluid is used that absorbs the heat of this process (O'out).
    A first drawback of casing and tube absorbers is that they are very bulky and heavy, which is a major problem in many installations.
    A second drawback of shell and tube absorbers is the need to perform heat extraction to achieve absorption, since it increases the need for heat input in the next step of the cycle that takes place in the generator.
    DESCRIPTION OF THE INVENTION
    The present invention solves the above problems thanks to a new configuration based on the use of microporous membranes that allows increasing the contact surface between the vapor phase refrigerant flow and the liquid phase solution flow. This configuration allows a much more compact absorber to be obtained, greatly reducing weight and volume compared to conventional absorbers. More specifically, the volume of an absorber according to the present invention can be about twice the volume of conventional absorbers used in high power machines, becoming an order of magnitude lower in the case of small power machines (lower at 15 kW).
    In addition, the absorber of the present invention is adiabatic in the sense that it does not require heat extraction for its operation, which is advantageous because it does not cause a decrease in the temperature of the solution to reduce the amount of heat to be provided. in the next step of the absorption cycle that takes place in the generator. In this way, it is possible to increase the overall performance of the absorption machine.
    On the other hand, since heat transfer is not necessary, the need to use thermal conductive materials is avoided. These materials are mainly metals, which implies a high weight, potential corrosion problems, and manufacturing processes that require relatively complex and specialized machinery. The absorber of the invention, on the other hand, can be manufactured almost entirely in plastic materials, which avoids all these problems. In addition, it can even potentially be manufactured using a conventional 3D printer.
    In accordance with the invention, an adiabatic absorber is described for an absorption machine that essentially comprises:
    a) A first channel and a second channel for a vapor phase refrigerant.
    b) A plurality of microchannels for a liquid phase solution separated from each other by thin walls. The plurality of microchannels is enclosed between the first channel and the second channel, a pair of microporous membranes interposing between said plurality of microchannels and the respective first channel and second channel. In addition, the microporous membranes are configured to pass the refrigerant in the vapor phase but to prevent the passage of the solution in the liquid phase.
    The operation of this new absorber is fundamentally the following. The refrigerant is passed in the vapor phase through the two outer channels and the solvent is passed in the liquid phase through the microchannels. Since only the microporous membrane separates the microchannels from the two outer channels, the pressure gradient between the pressure of the refrigerant vapor and the partial pressure of the refrigerant in the solution causes an exchange of matter through said porous membrane. This exchange is limited to the passage of the refrigerant vapor from the external channels to the microchannels through which the solution circulates, since the microporous membranes used do not allow the liquid phase to pass in the opposite direction. The result is that the concentrated solution that enters the microchannels is diluted as it passes through them due to the absorption of refrigerant and becomes a diluted solution at its exit.
    The microchannels can be implemented by perforations made in a flat plate of plastic material. This process can be carried out in different ways, although a simple possibility is the use of a 3D printer. In principle, the microchannels can be arranged according to different configurations, although preferably they are aligned along a straight line. As for their shape, in a preferred embodiment of the invention the microchannels have a rectangular cross section with their long side adjacent to the microporous membranes. This makes it possible to maximize the contact surface with said microporous membranes and therefore also the ability to transfer matter through them. On the other hand, the separation walls between the microchannels are as thin as the manufacturing method used allows, since the thinner these separation walls are, the less membrane surface will be rendered useless.
    According to an especially preferred embodiment of the invention, the ratio between the long side and the short side of the cross-section of the microchannels is equal to or greater than
    10. As the relationship between both sides increases, taking into account the analogy between heat and mass transfer processes, mass transfer coefficients increase. The results available in the scientific literature show that in rectangular channels the heat transfer increases as the relationship between both sides increases, because the relative importance of the corners and short sides decreases. Both the corners and the short sides, the speed of the fluid and therefore the convection worsens. The correlations used to predict the operation of the especially preferred embodiment of the invention have been experimentally validated to a ratio equal to 10.
    According to another preferred embodiment of the invention, the length of the short side of the microchannels is equal to or less than 150 J.Jm. As the length of this side increases, the thickness of the dissolution film increases, contributing to increase the resistance to mass transfer, so it is necessary that the length of the short side of the microchannels be small.
    On the other hand, the first and second channels for the vapor phase refrigerant are preferably essentially rectangular in shape. In addition, in another preferred embodiment they are externally delimited by an essentially adiabatic outer wall, since the absorber of the invention does not require heat exchange through said wall for operation. In this context, the term "essentially adiabatic outer wall" refers to an outer wall that is not specifically designed to facilitate heat transfer. This implies that the outer wall can be made of materials such as plastics or the like.
    As for microporous membranes, they can also be made of any material provided they have the properties mentioned above. More specifically, in a preferred embodiment of the present invention the porosity of the microporous membranes is equal to greater than 80%. As the porosity increases the flow of steam transferred through the membrane increases. However, excessively high porosity values may decrease the mechanical resistance of the membrane.
    According to yet another preferred embodiment, the absorber of the invention has a maximum length of 3 cm. The reason is that, although one might think that the longer the length the greater the performance of this absorber, the opposite effect actually occurs. The variation in the concentration of the solution as it absorbs refrigerant causes the pressure gradient between the partial pressure of the refrigerant in the solution that passes through the microchannels and that of the refrigerant that passes through the first and second channels to decrease, and therefore the rate of absorption of the refrigerant in the solvent also decreases. As a consequence, from a certain length, the absorber performance begins to decline.
    The present invention is also directed to an absorption machine comprising an absorber as described in the preceding paragraphs.
    BRIEF DESCRIPTION OF THE FIGURES
    Fig. 1 shows a scheme of an absorption cycle according to the prior art.
    Fig. 2 shows a cross section of an adiabatic absorber according to the present invention.
    PREFERRED EMBODIMENT OF THE INVENTION
    Fig. 2 shows a cross section of an absorber (1) according to the present invention where the different parts that compose it are appreciated.
    In the central area of the absorber (1) is a flat plate of plastic material provided with a plurality of perforations that constitute the microchannels (3). Between each pair of microchannels (3) a thin wall (4) is maintained whose sole function is to maintain
    Separate flows of dissolution of adjacent microchannels (3). Each of the microchannels (3) has a rectangular shape with a relationship between its long side (adjacent to the membrane) and its short side (adjacent to the thin wall (4)) equal to more than 10. In addition, since the plate Flat can be made of plastic material, it can be manufactured even by 3D printing.
    Two microporous membranes (5) are fixed to both sides of the flat plate, so that each microchannel (3) has two short sides delimited by thin walls (4) and two long sides delimited by microporous membranes (5). The microporous membranes (5) can be made of PTFE or the like, and are fixed to the base plate by any fastener that does not affect the passage of steam through them.
    As for its properties, as mentioned, the microporous membranes (5) must be permeable to refrigerant vapor but impervious to dissolution. Therefore, its characteristics will depend on the type of refrigerant and solvent used (lithium water bromide, ammonia-water, lithium ammonia-nitrate, water-lithium chloride, etc.), although in general they have a porosity equal to greater than 80% , a pore diameter of approximately 1 .1m, and a thickness of approximately 60.1m.
    On the opposite side of the microporous membranes (5) there is respectively the first channel (2a) and the second channel (2b), which are externally delimited by the essentially adiabatic outer walls (6). The first and second channels (2a, 2b) are also essentially rectangular in this example. The outer walls (6) can be made of plastic or the like.
    权利要求:
    Claims (9)
    [1]
    1. Adiabatic absorber (1) for an absorption machine, characterized by: -a first channel (2a) for a vapor phase refrigerant; - a second channel (2b) for a vapor phase refrigerant; -a plurality of microchannels (3) for a separate liquid phase solution
    each other by thin walls (4), said plurality of microchannels (3) being enclosed between the first channel (2a) and the second channel (2b), and where a pair of microporous membranes (5) interpose between the plurality of microchannels (3) and the respective first channel (2a) and second channel (2b), said microporous membranes (5) being configured to pass the refrigerant in the vapor phase but to prevent the passage of the solution in the liquid phase.
    [2]
    2. Absorber (1) according to claim 1, wherein the microchannels (3) are aligned along a straight line.
    [3]
    3. Absorber (1) according to claim 2, wherein the microchannels (3) have a rectangular cross section with their long side adjacent to the microporous membranes
    (5).
    [4]
    Four. Absorber (1) according to claim 3, wherein the ratio between the long side and the short side of the cross-section of the microchannels (3) is equal to or greater than 10.
    [5]
    5. Absorber (1) according to any of claims 3-4, wherein the length of the short side of the microchannels (3) is equal to or less than 150 iJm.
    [6]
    6. Absorber (1) according to any of the preceding claims, wherein the porosity of the microporous membranes (5) is equal to or greater than 80%.
    [7]
    7. Absorber (1) according to any of the preceding claims, wherein the first and second channels (2a, 2b) for refrigerant are essentially rectangular in shape.
    [8]
    8. Absorber (1) according to any of the preceding claims, wherein the first and second channels (2a, 2b) are externally delimited by an essentially adiabatic outer wall (6).
    [9]
    9. Absorber (1) according to any of the preceding claims, which has a maximum length of 3 cm.
    Absorption machine comprising an absorber (1) according to any of the preceding claims.
    类似技术:
    公开号 | 公开日 | 专利标题
    US4862708A|1989-09-05|Osmotic thermal engine
    ES2740050T3|2020-02-05|Air temperature and humidity control device
    ES2357010T3|2011-04-15|COOLING PROCEDURE.
    JP5599565B2|2014-10-01|System and method for managing the water content of a fluid
    KR101954965B1|2019-03-06|Apparatus for drying and/or cooling gas
    KR20070112370A|2007-11-23|A multi-orientational cooling system with a bubble pump
    JP2004218887A|2004-08-05|Cooling device of electronic element
    JP2009078246A|2009-04-16|Dehumidifier
    KR20130064936A|2013-06-19|Heat exchanger for vehicle
    KR101593815B1|2016-02-15|Apparatus and method for dehumidifier
    ES2647967B2|2018-06-13|ADIABAT ABSORBER FOR ABSORPTION MACHINE
    US20110061386A1|2011-03-17|Heat pipes for transferring heat to an organic rankine cycle evaporator
    US3677337A|1972-07-18|Heat transfer apparatus with osmotic pumping
    EP2212629A1|2010-08-04|Non-vacuum absorption refrigeration
    ES2814348T3|2021-03-26|Absorption refrigeration machine
    JP6459771B2|2019-01-30|Thermal transition heat pump
    JP5782368B2|2015-09-24|vacuum drying equipment
    RU2656037C1|2018-06-01|Pressure capillary pump
    KR100995419B1|2010-11-18|flat bifacial evaporator of loop heat pipe
    TWI595207B|2017-08-11|Heat exchanger
    Dwivedi et al.2015|Thermodynamic Analysis of Heat Pipe Using Ammonia, Water and Ethanol with a View to Being Used in Refrigeration
    JP4512596B2|2010-07-28|Cooling system
    ES2554550B1|2016-09-28|High thermal conductance device for multi-effect water desalination systems
    JP2006275423A|2006-10-12|Heat exchange system
    KR102125025B1|2020-06-19|Heat exahanging device
    同族专利:
    公开号 | 公开日
    WO2017203088A1|2017-11-30|
    ES2647967B2|2018-06-13|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    2018-06-13| FG2A| Definitive protection|Ref document number: 2647967 Country of ref document: ES Kind code of ref document: B2 Effective date: 20180613 |
    优先权:
    申请号 | 申请日 | 专利标题
    ES201630682A|ES2647967B2|2016-05-26|2016-05-26|ADIABAT ABSORBER FOR ABSORPTION MACHINE|ES201630682A| ES2647967B2|2016-05-26|2016-05-26|ADIABAT ABSORBER FOR ABSORPTION MACHINE|
    PCT/ES2017/070356| WO2017203088A1|2016-05-26|2017-05-26|Adiabatic absorber for an absorption machine|
    [返回顶部]