ADSORPTION PRLNCIHE

Tbchnical field

[0001] Hie present invention relates in general to an improved chemical heat pump.

Background

[0002] In prior art heat pumps are described which comprise a unit tube wherein a partof the tube encloses both a reactor and a condenser evaporator (Jig 1). An example of such a heat pump according to the state of the art is described in WO 2009/ 070090.

[0003] A disadvantage of the above described unit tube is that the vapor or gas which is formed when a volatile liquid evaporates has to be transported a long way through the unit tube during charge and discharge. Thereby a pressure drop occurs which impairs the possibility of the chemical heat pump to utilize small temperature differences between a heat source and a heat sink A long transportation path for the gas implies that when the gas/ vapor condenses and returns to the liquid phase, there is a risk that the liquid phase is distributed unevenly in the reactor and condenser/ evaporator part respectively of the chemical heat pump. Uneven distribution of liquid may lead to gradual loss of efficiency when the heat pump is charged and discharged repeatedly.

[0004] Thus there is a need for an improved heat pump with reduced losses and improved durability of the efficiency during long term use.

Summary

[0005] It is an objectof the present invention to obviate atleast some of the disadvantages in the prior art and provide an improved chemical heat pump [0006] The chemical heat pump can be used as a chemical heat pump working according to the absorption principle and also as a chemical heat pump working according to the adsorption principle. In both versions there is a reactor part and a condenser/ evaporator part

[0007] In a first aspect there is provided a chemical heatpump working

according to the absorption or adsorption principle comprising an active substance and a volatile liquid, wherein the volatile liquid is adapted to be absorbed or be adsorbed by the active substance at a first temperature and be desorbed by the active substance at a second higher temperature, wherein the chemical heatpump further comprises at least a first tube 1 and at least a second tube 2, wherein the second tube 2 is at least partially positioned within the first tube 1 and essentially along at least a part of the longitudinal axis of said first tube 1, wherein the active substance is applied at least partially in a space between the inside 3 of the first tube 1 and the outside 4 of the first tube 2, wherein a first matrix 5 adapted for storage of the volatile liquid is at least partially applied on the outside 4 of the second tube 2.

[0008] Further embodiments are defined in the appended claims, which are specifically incorporated herein by reference.

[0009] Advantages of the invention compared to the prior art include but are not limited to; less material is required, the manufacture is simpler, the energy efficiency is improved, the lifetime is extended and a lasting high efficiency is obtained, the number of applications is increased.

Brief description of the drawings

[0010] The invention is now described, by way of example, with reference to the accoirpanying drawings, in which: [0011] ilg. 1 shows a heatpump according to the state of the artcomprising a reactor and a condenser/ evaporator in different parts of a tube.

[0012] Jig 2 shows a longitudinal cross section of one embodiment of the present chemical heatpump comprising a first tube 1 with an inside 3, a second matrix 10, a fourth heat conducting layer 9, a first layer 6 which is permeable to the volatile liquid in gas phase, a second tube 2 with an outside 4, a first matrix 5, a second layer 7 which is permeable to the volatile liquid in gas phase, and a third layer 8.

[0013] Jig 3 shows a cross section of the chemical heatpump depicted in fig 2, and

[0014] Jig 4 shows a chemical heatpump as a solar panel adapted to be heated by the sun, comprising a second tube 2 and an energy transfer device 11.

Detailed description

[0015] Before the invention is disclosed and described in detail, it is to be understood that this invention is not limited to particular compounds,

configurations, method steps, substrates, and materials disclosed herein as such compounds, configurations, method steps, substrates, and materials may vary somewhat lis also to be understood that the terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting since the scope of the present invention is limited only by the appended claims and equivalents thereof.

[0016] Itmustbe noted that, as used in this specification and the appended claims, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. [0017] ff nothing else is defined, any terms and scientific terminology used herein are intended to have the meanings commonly understood by those of skill in the art to which this invention pertains.

[0018] The term "about" as used in connection with a numerical value

throughout the description and the claims denotes an interval of accuracy, familiar and acceptable to a person skilled in the art Said interval is ± 10 .

[0019] "Ceramic material" is used herein to denote an inorganic non*netallic, material that can be crystalline or amorphous.

[0020] There is disclosed a chemical heatpump working according to the

absorption or adsorption principle comprising an active substance and a volatile liquid, wherein the volatile liquid is adapted to be absorbed or adsorbed by the active substance at a first temperature and desorbed by the active substance at a second higher temperature, the chemical pump further comprises at least one first tube 1 and at least one second tube 2, the second tube 2 is at least partially positioned inside said first tube 1 and substantially along at least a part of the longitudinal axis of said first tube 1, wherein the active substance is applied at least partially in a space between the inside 3 of the first tube 1 and the outside 4 of the second tube 2, wherein on the outside 4 of the second tube 2 there is at least partially applied a first matrix 5 adapted for storing the volatile liquid.

[0021] In one embodiment, the active substance is at least partially positioned on the inside 3 of the first tube 1 and the active substance is kept fixed to the inside 3 of said first tube 1 with a first layer 6 permeable to the volatile liquid in the gas phase. In one embodiment the first layer 6 comprises a metal mesh. In one embodiment the first layer 6 comprises copper. [0022] In one embodiment, the first matrix 5 is held on the outside of the second tube 2 with a second layer 7 permeable to the volatile liquid in gas phase.

[0023] In one embodiment at least one third layer 8 is positioned between the inside 3 of the first tube 1 and the outside 4 of the second tube 2 so that gas can pass from the first tube 1 to the second tube 2. This has the advantage that thermal radiation from the reactor part to the condenser/ evaporator partis reduced, so thatthe gas transport between the reactor part and

condenser/ evaporator part still is allowed. The function of the third layer 8 is to reflect as much as possible of the thermal radiation that emanates from the reactor part towards the condenser/ evaporator part Thereby radiation losses in the chemical heat pump and the condenser/ evaporator partis protected from thermal radiation.

[0024] The third layer 8 may for example be designed so thatthe layer surface is always parallel to the adjacent reactor surface. Thanks to the third layer 8, most of the thermal radiation is reflected, including thermal radiation from the reactor and only a small percentage is absorbed by the reflective material. The proportion of thermal radiation that is still absorbed by the reflective material is then transported with low efficiency through the material with low thermal conductivity and will subsequently radiate out from the material. In one embodiment about 90% of the thermal radiation is reflected directly back towards the heat source, irom the surface of the third layer 8 there is emitted further heat radiation back to the heat source because only a small part of the retraining about 10% of the thermal radiation of one embodiment can be lead away through the ceramic part of the third layer 8. The proportion of energy which penetrates the third layer 8 is very small, or in one embodiment about 2% of the total radiated energy supply. The third layer 8 also serves as a splash guard to prevent possible scattering of me active substance from the reactor to the condenser/ evaporator. In one embodiment, the third layer 8 is adapted to reflect thermal radiation. In one embodiment the third layer 8 comprises a ceramic material coated with a metal. In one embodiment, the ceramic material is glass. In one embodiment, the metal on the ceramic material is copper. In one embodiment, the metal layer has a thickness of 100 A or less. In one

embodiment, the third layer 8 displays a reflectance of thermal radiation in the range 350-550 Kof atleast80 , preferably at least 90%.

[0025] In one embodiment at least a fourth heat conductive layer 9 is arranged between the inside 3 of the first tube 1 and the active substance. In one embodiment, the fourth heat conductive layer 8 comprises at least one metal. In one embodiment, the fourth heat conductive layer 8 comprises copper. One advantage of the fourth heat conductive layer 8 is that efficient conduction of heat to the active substance is obtained. I ^" the material of the first tube 1 in itself conducts heat well from the external environment to the active substance the need for such a fourth heat conductive layer 8 is reduced.

[0026] In one embodiment, the active substance is matter that can adsorb the volatile liquid.

[0027] In one embodimenta second matrix 10 is positioned at least partially on the inside 3 of the first tube 1, wherein the second matrix 10 is adapted to store the active substance.

[0028] In one embodimentthe active substance is a substance thatcan absorb the volatile liquid. Examples of such substances include but are not limited to metal salts. Examples of metal salts include but are not limited to magnesium chloride, magnesium bromide, lithium bromide, and lithium chloride. In one embodimentthe active substance has at the first temperature a solid state, from which the active substance at absorption of the volatile liquid and its gas phase immediately is transformed at least partially to the liquid state or solution phase and at the second temperature has a liquid state or is in solution phase, from which the active substance by desorbing the volatile liquid, in particular its gas phase, immediately transforms at least partially to the solid state. 29] In one embodiment an energy transfer device 11 is in thermal contact with the first tube 1 wherein the energy transfer device 11 comprises at least one tube with a first and a second end, the first end is positioned lower than the second end and wherein the energy transfer device 11 comprises a fluid. An energy transfer device 11 or a "heat pipe" means a device in which energy can be moved from point A to point B without the use of pumps with mechanical, often moving parts. In a heat pipe or energy transfer device, energy is transferred so that a liquid is for instance in a tube wherein one end A of the tube (the evaporator part) by heat turns the liquid into gaseous form and whereby the gas subsequently is transported through the lower gas pressure prevailing in the tube' s second end B (the condenser part) so that the gas will be liquefied at B which is both relatively higher positioned and colder than A. Due to the lower temperature atB the gas will return to liquid state, i.e. it will be condensed atB The liquid formed at condenser part B will due to gravity flow back to A, where the liquid after heating again will be transformed to gas phase. This cycle of evaporation at A and condensation atB implies that an amount of energy is moved from A to B with small losses. In one embodiment, the heat conduction of said energy transfer device is regulated. Thus, the thermal conduction can in one embodimentbe switched off or switched on. In one embodiment, the regulation is made with a valve. In alternative embodiments, other modes of regulation are possible. [0030] In one embodiment me tube 1 is adapted to be heated by an energy source.

[0031] In one embodiment me tube 1 is adapted to be heated by solar energy.

[0032] In one embodimentme tube 1 is in me rmal contact with me cooling system of a combustion engine.

[0033] In one embodimentme tube 1 is in thermal contact with a boiler.

[0034] In one embodimentme tube 1 is in thermal contact with a district

heating plant

[0035] In one embodimentme tube 1 is in contact with a liquid in a district heating plant

[0036] The present chemical heatpump is designed as a first tube 1 with the reactor part and the condenser/ evaporator part in the same tube part In one embodimentme wall of the first tube 1 comprises different materials that are adapted to the intended use. Examples include but are not limited to glass at a solar panel application and metal when using industrial waste heat and other applications.

[0037] The active substance along with the optional metal plate 9 and the first metal net 6 represents the reactor part of the chemical heatpump.

[0038] Heat exchange to and from the reactor part can be solved in different ways, examples include but are not limited to positioning a metal tube in connection with the reactor part on the inside 3 of the unit tube 1 or by positioning a metal tube directly on the outer side of the unit tube 1. The latter embodiment requires that the unit tube itself conducts heat to and from the reactor part [0039] The condenser/ evaporator part of the chemical heatpump is found in the central cavity of the unit tube 1. A second tube 2 for heat exchange to and from the condenser/ evaporator partis arranged in the first tube 1. In one embodiment, the second tube 2 is arranged in the center of the first tube 1. A first matrix 5 is arranged at least partially around the second tube 2. The first matrix 5 is held against the metal tube 2 by a second layer 7. The first matrix 5 together with the second layer 7 is the condenser/ evaporator part of the chemical heatpump, where the first matrix 5 is used for storing the volatile liquid.

[0040] Both the first layer 6 and the second layer 7 are permeable to the

volatile liquid in the gas phase and thus allow a flow of the volatile liquid in the gas phase.

[0041] The firsttube 1 is sealed and there is vacuum inside it

[0042] I¾iring the charging phase the firsttube 1 is heated by a heat source.

Examples of heat sources include but are notlimited to radiation from the sun, heat from a combustion engine, waste heat from a boiler, and waste heat from industrial processes. The heating of the firsttube 1 may be director through another device. Examples of other devices include, but are notlimited to a metal tube on the outside of the firsttube 1. The heat is transferred to the reactor part and the active substance, whereby gas desorbs. The transfer of heat to the active substance can be performed in various alternative ways, examples include but are notlimited to a metal plate arranged between the inside 3 of the first tube 1 and the active substance, or directly through the inside 3 of the first tube 1.

[0043] The gas formed finds its way inwards from the active substance towards the condenser/ evaporator part, which during charging of the chemical heat pump is cooled by using a heat-conveying medium circulating in the second tube 2. The gas condenses into a liquid phase that is sucked up into and stored in the first matrix 5.

[0044] I¾iring discharge the condenser/ evaporator partis heated using a heat-conveying medium circulating in the second tube 2. Volatile liquid in gas phase begins to desorb from the liquid phase which is collected in the first matrix 5. The gas finds its way outwards through the second layer 7 and further on to the reactor part During discharge the reactor partis kept cooled whereby the gas condenses to a liquid phase which is absorbed or adsorbed by the dry active substance.

[0045] In the following the advantages of the invention are described in more detail: The invention provides direct cost benefits because less material is required and because of a simplified production process. Material consumption is reduced because a vacuum housing to the condenser/ evaporator is not needed when the reactor and condenser/ evaporator are enclosed in a common vacuum housing. Material consumption is reduced further since the condenser is placed in an area that is already insulated because of the vacuum conditions and the optional third layer 8. This eliminates the need for insulating materials and a coating of the insulation material. When the condenser of the present invention is integrated inside the reactor the need for a special gas channel is eliminated. The vacuum housing, gas channel and insulation including coating constitute a major part of the material consumption and the total amount of material used is in one embodiment reduced by about50 compared to the prior art

[0046] The invention achieves increased energy efficiency due to a reduced transport distance for the gas. The distance of the formed gas to be transported between the reactor part and the condenser/ evaporator part has radically been reduced. The gas moves essentially in a radial direction in the device according to the present invention. Thanks to the essential radial transport of the gas, the average transport distance of the gas is only a fraction compared to the prior art

[0047] The shortened transport distance of the gas leads to a significantly lowered pressure drop. The pressure drop can be approximated using the formula below: wherein μ = viscosity of the gas w = velocity of the gas

L= transport distance of the gas

¾ = hydraulic diameter p = density ξ _; = coefficient for local resistance.

[0048] Compared with the chemical heat pumps according to the art, the shortened gas transport distance of the pre sent invention implies a reduction of the pressure drop which can result in a pressure loss which is only a fraction of the pressure drop according to the prior art The reduced pressure drop in turn results in a noticeable increase of the usable energy and that cooling can be delivered with the same efficiency at a lower temperature and higher temperature, respectively, with the same efficiency for heating. [0049] The invention provides extended service life with sustained high performance. The risk for an uneven distribution of liquid in the matrix is reduced because the distance over which the gas travels is short and also uniformly distributed over the reactor and the condenser/ evaporator, respectively. There are no disadvantaged positions such as in the prior art This results in a prolonged service life and maintained efficiency during the entire service life.

[0050] The invention provides an extended range of applications. The first tube 1 can be produced in virtually any length because the gas transportation is not dependent on the length of the first tube 1, but instead on its diameter. The first tube 1 can for example consist of glass and as a solar collector, but itcan also consist of a copper tube. Because the first tube 1 is virtually not dependent on the length, the number of applications is increased because the chemical heat pump can be flexibly adapted to the product of the chemical heat pump to operate in. Examples of such products include but are not limited to:

• AH sizes of commercially available solar collectors

• Heat pumps for cooling or heating with waste heat from a combustion engine.

• Heat pumps for cooling or heating with waste heat from a boiler.

• Heat pumps for heating or cooling directly from a pipe of a district heating installation.

• Energy transport of industrial waste heat

[0051] Example

Tests were conducted in a chemical heat pump according to the present invention. Testing was conducted in a test station where the rays of the sun could be simulated under different conditions. As the active substance IiCl was used and the volatile liquid was water. The active substance was stored in a matrix in the reactor part of the chemical heat pump. [0052] The chemical heat pump was charged in the test station using simulated sunlight during about 12 hours. Water evaporated during the charge and was transported from the reactor part to the condenser part of the chemical heat pump. In the cooled condenser part the steam condensed back into water.

[0053] Since the gas transport distance of this chemical heatpump has been reduced substantially compared to previously known chemical heat pumps, an increased measured power was expected in the present test After the chemical heatpump had charged and discharged about 3 times, an average power of 140 W was measured at discharge. Ey comparison, the average powers during the discharge of known chemical heat pumps, where the same kind of active substance (IiCl) and the same concentration of this substance in the same volatile solvent (water) was used, measured about 40 W. From these tests it can be concluded that this chemical heatpump in this experiment gives an

approximately 3.5iold higher power at discharge than previously known chemical heat pumps.

[0054] Other features and uses of the invention and their associated

advantages will be evident to a person skilled in the art upon reading the description and the examples.

[0055] It is to be understood that this invention is notlimited to the particular embodiments shown here. The following examples are provided for illustrative purposes and are not intended to limit the scope of the invention since the scope of the present invention is limited only by the appended claims and equivalents thereof.