Patent Publication Number: US-2016245554-A1

Title: Cooling device and method for cooling a medium

Description:
The present invention relates to a cooling apparatus for cooling a medium. 
     Such cooling apparatuses are used, in particular, in production plants in order to efficiently remove heat arising in production processes to the surroundings. For example, it can be provided for a cooling apparatus to use river water from a river adjoining the production plant to effect cooling. Particularly in summer, when there is a great need for cooling, it is usually possible to transfer only a small quantity of heat to the river water because of legal requirements. This can result in production engineering and economic difficulties. 
     It is an object of the present invention to provide a cooling apparatus by means of which a large quantity of heat can be removed efficiently. 
     This object is achieved according to the invention by a cooling apparatus for cooling a medium, which comprises the following: 
     an evaporation apparatus for evaporating water;
 
a vacuum apparatus for generating a subatmospheric pressure in an evaporation space of the evaporation apparatus;
 
a loading apparatus which comprises a loading space which is fluidically connected to the evaporation space of the evaporation apparatus and is at least partly filled with an absorption medium for absorbing the evaporated water;
 
an unloading apparatus by means of which the water absorbed by the absorption medium can be removed from the absorption medium and released into surroundings of the cooling apparatus.
 
     For the purposes of the present invention, absorption of water by means of the absorption medium is, in particular, a physical and/or chemical reaction of the water with the absorption medium. The reaction is, in particular, reversible. For example, it can be provided for the water to be absorbed, taken up, adsorbed by the absorption medium and/or be incorporated into the absorption medium. 
     The absorption medium is preferably a constituent of a thermochemical store by means of which surplus heat can be utilized not only for providing heat but also for covering and/or buffering a cooling requirement. 
     The cooling apparatus preferably comprises an open cooling circuit in which cooling water is not only utilized perceptibly by effecting a temperature increase but also by evaporation. In this way, at the same refrigeration requirement, the amount of cooling water necessary can preferably be reduced significantly, for example by up to a factor of 60. 
     During the absorption and/or release of water by the absorption medium, preference is given to heat being released or heat being absorbed. The absorption of water is thus preferably exothermic or endothermic. Correspondingly, the release of water is preferably endothermic or exothermic. 
     It can be advantageous for the unloading apparatus to comprise an unloading space in which the water absorbed by the absorption medium can be removed from the absorption medium, with the unloading space preferably being spatially separated from the loading space of the loading apparatus. 
     It can be advantageous for the unloading space to have a higher pressure than the loading space during cooling operation of the cooling apparatus. 
     The unloading space is preferably fluidically connected to surroundings of the cooling apparatus. The unloading space preferably has, at least approximately, the pressure of the surroundings, in particular atmospheric pressure. 
     The absorption medium preferably comes into direct contact with unloaded hot air in the unloading space in order to remove the water from the absorption medium. The unloaded hot air then preferably carries the water removed from the absorption medium into the surroundings of the cooling apparatus. 
     Instead of direct contact between the unloaded hot air and the absorption medium, it is also possible for indirect heat transfer to be provided. Here, the water removed from the absorption medium preferably collects in vapor form in a space which can be opened, for example, by means of a valve, to release the water into the surroundings. 
     It can be advantageous for the cooling apparatus to comprise a transport apparatus for transporting the absorption medium from the loading space to the unloading space. 
     As an alternative or in addition, the cooling apparatus can comprise a transport apparatus for transporting the absorption medium from the unloading space to the loading space. 
     In particular, it can be provided for the cooling apparatus to comprise a transport apparatus by means of which the absorption medium can be transported both from the loading space to the unloading space and from the unloading space to the loading space. 
     It can be provided for the cooling apparatus to comprise at least one lock device through which the absorption medium can be transported from a subatmospheric pressure side of the cooling apparatus, to which the evaporation space and/or the loading space is assigned, to a high-pressure side of the cooling apparatus, to which the unloading space is assigned. 
     In the present description and the accompanying claims, a subatmospheric pressure is, in particular, a pressure below ambient pressure/atmospheric pressure, for example not more than about 500 mbar, in particular not more than about 100 mbar, preferably not more than about 50 mbar. 
     In the present description and the accompanying claims, the term “high pressure” refers to, in particular, a pressure which corresponds essentially to or is above ambient pressure and/or atmospheric pressure. 
     In one embodiment of the invention, the cooling apparatus can comprise at least one lock device through which the absorption medium can be transported from a high-pressure side of the cooling apparatus, to which the unloading space is assigned, to a subatmospheric pressure side of the cooling apparatus, to which the evaporation space and/or the loading space is assigned. 
     In particular, the cooling apparatus can comprise a transport apparatus for transporting the absorption medium in a closed circuit. The absorption medium can in this case preferably be transported from the loading space to the unloading space and, in particular along a separate route, back to the loading space, etc. 
     It can be advantageous for the cooling apparatus to comprise a water feed apparatus for feeding liquid water to the evaporation apparatus. 
     The cooling apparatus preferably comprises at least one heat exchanger by means of which heat can be transferred from a medium to be cooled to the evaporation apparatus, in particular to the water to be evaporated in the evaporation apparatus. 
     The absorption medium is preferably a liquid or a solid. In particular, it can be provided for the absorption medium to be free-flowing. The absorption medium can, for example, be a bulk material and/or a powder. 
     In one embodiment of the invention, the absorption medium can comprise salt, aqueous salt solution, silica gel, minerals, hydroxide, ionic liquid and/or zeolite or be formed by salt, aqueous salt solution, silica gel, minerals, hydroxide, ionic liquid and/or zeolite. 
     It can be advantageous for the cooling apparatus to comprise at least one degassing apparatus for degassing the water to be fed to the evaporation apparatus and/or at least one degassing apparatus for degassing the absorption medium to be loaded with water. 
     The vacuum apparatus for generating the subatmospheric pressure in the evaporation space of the evaporation apparatus can, for example, be formed by a transport apparatus for transporting the absorption medium. 
     The cooling apparatus preferably comprises at least one heat exchanger by means of which heat can be transferred from an external heat source to the absorption medium arranged in an unloading space. 
     The cooling apparatus, in particular the unloading apparatus, comprises, in particular, at least one flushing apparatus for flushing the unloading space with a flushing medium. The flushing medium is, for example, dry hot air which can be passed through the unloading space of the unloading apparatus. 
     The absorption medium is preferably heated in the unloading space by means of the flushing medium and/or by means of an external heat source, as a result of which the water is preferably removed from the absorption medium. The water is, in particular, released in gaseous or vapor form and removed by means of the flushing medium from the unloading space. 
     The cooling apparatus of the invention is particularly suitable for carrying out a method for cooling a medium. 
     The present invention therefore also provides a method for cooling a medium by means of a cooling apparatus. 
     In this respect, the present invention has the object of providing a method by means of which a medium can be cooled efficiently and using a very small amount of cooling medium, in particular water. 
     This object is achieved according to the invention by a method for cooling a medium by means of a cooling apparatus, wherein the method comprises the following: 
     application of subatmospheric pressure to an evaporation space of an evaporation apparatus;
 
introduction of liquid water into the evaporation space;
 
evaporation of the water in the evaporation space;
 
introduction of the evaporated water from the evaporation space into a loading space of a loading apparatus which is fluidically connected to the evaporation space and is at least partly filled with an absorption medium for absorbing the evaporated water;
 
absorption of the evaporated water by means of the absorption medium;
 
removal of the water absorbed by the absorption medium from the absorption medium and release of the water into surroundings of the cooling apparatus.
 
     The method according to the invention preferably has one or more of the features and/or advantages described in connection with the cooling apparatus of the invention. 
     Furthermore, the cooling apparatus of the invention preferably has individual features and/or advantages or a plurality of features and/or advantages of the method according to the invention. 
     The release of the water into the surroundings is preferably effected in gaseous or vapor form. 
     It can be advantageous for the absorption medium to be taken from the loading space after absorption of the water and introduced into an unloading space of an unloading apparatus of the cooling apparatus. 
     In order to remove the water absorbed by the absorption medium from the absorption medium, the absorption medium is preferably heated to a temperature which exceeds the temperature of the medium to be cooled by means of the cooling apparatus before cooling of the medium. 
     The water introduced into the evaporation apparatus preferably has a temperature of not more than about 25° C., in particular not more than about 20° C., for example not more than about 15° C. 
     To remove the water from the absorption medium, the absorption medium is preferably heated to a temperature of at least about 80° C., for example at least about 90° C., preferably at least about 100° C. 
     It can be advantageous for the absorption medium to be cooled after removal of the water absorbed by the absorption medium from the absorption medium and/or before introduction of the absorption medium into the loading space. 
     Furthermore, the cooling apparatus of the invention and/or the method according to the invention can have one or more of the features and/or advantages described below: 
     The water can preferably be evaporated under subatmospheric pressure, for example at about 10° C., by means of the cooling apparatus. 
     The main cooling effect of the cooling apparatus is preferably achieved by evaporation of the water under subatmospheric pressure. 
     The absorption medium (reaction medium), which is, in particular, circulated, is preferably partly conveyed under subatmospheric pressure and partly under ambient pressure (high pressure). 
     The cooling apparatus of the invention can, in particular, be utilized when cooling is actually not available in another way, for example when conventional heat pumps fail. 
     Particularly when the absorption medium is circulated and, for example, is cooled before being introduced into the loading space, continuous operation of the cooling apparatus can be possible. 
     The cooling water used for cooling is preferably not merely heated perceptibly but evaporates. In conventional, customary heating by 10 K, the quantity of heat which can be taken up is about 41 kJ/kg. The quantity of heat which can be taken up by evaporation is, on the other hand, about 2503 kJ/kg. According to the invention, the cooling potential of the water used can thus be increased by a factor of about 60. The cooling water requirement thus decreases drastically at a given cooling power. 
     It is preferably not necessary for the cooling water to be fed back into a river after heat has been taken up since it has preferably been released in gaseous or vapor form into the surroundings. 
     The absorption medium preferably makes it possible for the time at which the waste heat is utilized, in particular for unloading the absorption medium, to be decoupled from the time at which the cooling function takes place, in particular during loading of the absorption medium. 
     Particularly when the absorption medium can be transported, it is possible to use an inexpensive reactor (loading space) which is, in particular, optimized for the required cooling power (evaporator power). A large storage apparatus for accommodating the absorption medium can then preferably be dispensed with. 
     Preference is given to using industrial waste heat, for example at a temperature level of about 100° C., for unloading the absorption medium. 
     The absorption medium preferably has a high affinity for water. In particular, the absorption medium is preferably strongly hygroscopic. 
     The water is preferably introduced in liquid form into the cooling apparatus and released in gaseous and/or vapor form from the cooling apparatus into the surroundings. 
     The cooling apparatus of the invention is particularly suitable for cooling industrial processes, for providing a predetermined cooling power and/or to supplement existing cooling apparatuses to cover peak loads. 
     Further preferred features and/or advantages of the invention are indicated in the following description and the depiction of a working example. 
    
    
     
       The drawings show: 
         FIG. 1  a schematic depiction of a cooling apparatus in which liquid water is evaporated under subatmospheric pressure and released in vapor and/or gaseous form into surroundings of the cooling apparatus. 
     
    
    
     Identical or functionally equivalent elements are denoted by the same reference numerals in the FIGURE. 
     A cooling apparatus which is shown in  FIG. 1  and is denoted as a whole by  100  serves, in particular, for cooling a medium which is, for example, fed into a heat exchanger  102 . 
     The cooling apparatus  100  comprises an evaporation apparatus  104  for evaporating water and a water feed apparatus  106  by means of which liquid water can be introduced into the evaporation apparatus  104 . 
     Furthermore, the cooling apparatus  100  comprises a vacuum apparatus  108  by means of which a subatmospheric pressure can be applied to a subatmospheric pressure side  110  of the cooling apparatus  100 . 
     In particular, a subatmospheric pressure, i.e. a pressure below ambient pressure or atmospheric pressure, for example about 100 mbar, can be generated in an evaporation space  112  of the evaporation apparatus  104  by means of the vacuum apparatus  108 . 
     Owing to the subatmospheric pressure in the evaporation space  112 , the liquid water fed to the evaporation apparatus  104 , in particular the evaporation space  112 , can be evaporated even at relatively low temperatures. 
     The cooling apparatus  100  further comprises a loading apparatus  114  which comprises a loading space  116 . 
     The loading space  116  is at least partly filled with an absorption medium. The evaporated water can, in particular, be absorbed by means of the absorption medium. 
     The loading space  116  and the evaporation space  112  are for this purpose fluidically connected to one another, so that the water evaporated in the evaporation space  112  can go into the loading space  116 . 
     The absorption medium can, after the absorption of water, be discharged from the loading space  116  and introduced into an unloading space  120  of an unloading apparatus  122  by means of one or two transport apparatuses  118  of the cooling apparatus  100 . 
     In particular, the water can be removed from the absorption medium by means of the unloading apparatus  122 . 
     A transport apparatus  118  arranged downstream of the loading space  116  in a transport direction  124  preferably forms a lock device  126  by means of which the absorption medium initially present on the subatmospheric pressure side  110  of the cooling apparatus  100 , i.e. in the subatmospheric pressure region, can be transported to a high-pressure side  128  of the cooling apparatus  100 , i.e. at least approximately ambient pressure. 
     The unloading apparatus  122  is arranged on this high-pressure side  128  of the cooling apparatus  100  so that, for example, the ambient pressure prevails in the unloading space  120  of the unloading apparatus  122  and the water which has been absorbed by the absorption medium can be removed at ambient pressure from the absorption medium. 
     The unloading space  120  of the unloading apparatus  122  is coupled to a heat exchanger  130  of the cooling apparatus  100 . 
     By means of the heat exchanger  130 , heat from an external heat source  132  can be transferred to the absorption medium located in the unloading space  120 . 
     The absorption medium can, in particular, be heated to a high temperature, for example up to about 100° C. 
     The unloading space  120  is open to surroundings  134  of the cooling apparatus  100  so that water given off from the absorption medium can escape into the surroundings  134 . 
     The cooling apparatus  100  further comprises a flushing apparatus  136  by means of which a flushing medium, for example dry hot air, can be introduced into the unloading space  120 . 
     The unloading space  120  and the absorption medium present therein can thus be flushed particularly simply by means of the flushing apparatus  136 , firstly in order to heat the absorption medium and secondly to discharge the water given off from the absorption medium from the unloading space  120  and finally release it into the surroundings  134 . 
     To optimize the function of the cooling apparatus  100 , one or more degassing apparatuses  138  of the cooling apparatus  100  are additionally provided. In particular, the liquid water to be fed to the evaporation apparatus  104  can be degassed by means of these degassing apparatuses  138 . Furthermore, the absorption medium to be introduced into the loading space  116  can be degassed by means of a degassing apparatus  138 . 
     The transition from the high-pressure side  128  to the subatmospheric pressure side  110  of the cooling apparatus  100  can, in particular, be realized by means of throttle valves  140  of the cooling apparatus  100 . 
     In particular, a desired subatmospheric pressure on the subatmospheric pressure side  110 , in particular in the evaporation space  112  and/or in the loading space  116 , can be achieved in a targeted manner by means of the throttle valves  140 . 
     Finally, the loading apparatus  114  preferably additionally comprises an extraction apparatus  142 . A gas, in particular inert gas, which during operation of the cooling apparatus  100  accumulates in the loading space  116  can preferably be discharged from the loading space  116  by means of the extraction apparatus  142 . 
     In the cooling apparatus  100 , a closed absorption medium circuit  144  is firstly formed. The absorption medium circuit  144  comprises the loading space  116 , the transport apparatus  118 , the unloading space  120 , a degassing apparatus  138 , a throttle valve  140  and a further transport apparatus  118 . 
     In the absorption medium circuit  144 , the absorption medium can thus be fed from the loading space  116  through the lock device  126  into the unloading space  120 . The unloaded medium can subsequently be fed from the unloading space  120  through the degassing apparatus  138  and the throttle valve  140  and through the lock device  126  back into the loading space  116 . 
     The cooling apparatus  100  further comprises a water transport section  146 . 
     The water transport section  146  comprises a throttle valve  140 , the water feed apparatus  106 , a degassing apparatus  138 , the evaporation space  112 , the loading space  116 , a transport apparatus  118 , the unloading space  120  and finally the surroundings  134 . 
     By means of the water transport section  146 , the initially liquid water can firstly be fed through the throttle valve  140  and via the water feed apparatus  106  into the evaporation space  112  and be evaporated therein. The evaporated water can be fed into the loading space  116  and absorbed there by means of the absorption medium. 
     The absorbed water can be fed together with the absorption medium via the transport apparatus  118  and thus through the lock device  126  into the unloading space  120 , there be removed from the absorption medium and finally be released, in particular together with a flushing medium, into the surroundings  134 . 
     The water transport section  146  is thus not closed. Rather, the initially liquid water can be fed to the cooling apparatus  100  and be released in gaseous or vapor form into the surroundings  134 . 
     The above-described cooling apparatus  100  functions as follows: 
     a medium to be cooled by means of the cooling apparatus  100  is fed into a heat exchanger  102  which is thermally coupled to the evaporation apparatus  104 . 
     In order to withdraw heat from the medium to be cooled, water is evaporated in the evaporation apparatus  104 . 
     The initially liquid water is for this purpose conveyed through the throttle valve  140  and via the water feed apparatus  106  into the evaporation space  112 . 
     A subatmospheric pressure preferably prevails in the evaporation space  112  so that the water evaporates even at very low temperatures and thus takes up heat. 
     In particular, the evaporating water withdraws heat from the medium to be cooled. 
     The water which is now present in vapor or gaseous form next goes into the loading space  116  in which it comes into contact with a strongly hygroscopic absorption medium and is absorbed by the absorption medium. 
     The absorption medium is, in particular, a salt or an aqueous salt solution. 
     The absorption medium loaded with water is subsequently discharged from the loading space  116 . In particular, the absorption medium loaded with water is taken by means of the transport apparatus  118  from the loading space  116  and fed into the unloading space  120  of the cooling apparatus  100 . 
     The absorption medium here passes through the lock device  126  and is thus conveyed from the subatmospheric pressure side  110  of the cooling apparatus to the high-pressure side  128  of the cooling apparatus  100 . 
     In particular, ambient pressure, for example atmospheric pressure, prevails on this high-pressure side  128 . 
     In the unloading space  120 , the absorption medium loaded with water is heated by introduction of heat in order to remove the water absorbed in the absorption medium from the absorption medium. 
     Owing to the relatively high pressure, namely ambient pressure, which now prevails, a relatively high temperature of, for example, about 100° C. is required to remove the water in gaseous or vapor form from the absorption medium and finally release it into the surroundings  134  of the cooling apparatus  100 . 
     This high temperature is achieved, in particular, by transfer of heat from an external heat source  132  to the absorption medium and/or by introduction of dry hot air into the unloading space  120  by means of the flushing apparatus  136 . 
     After the water has been at least partly removed from the absorption medium, the absorption medium can be reused for the absorption of water. 
     The absorption medium is for this purpose fed, in particular, through a further throttle valve  140  and a further lock device  126  back into the loading space  116 . 
     In order to reduce the temperature of the absorption medium which has been heated in the unloading space  120  and thus increase the efficiency of the cooling apparatus  100 , the absorption medium can be cooled by means of a cooling device (not shown) before being introduced into the loading space  116 . 
     The absorption medium is then able, in particular, to be conveyed in a continuous circuit, namely the absorption medium circuit  144 . 
     The cooling apparatus  100  can then be, in particular, operated continuously. 
     When the cooling apparatus  100  is looked at overall, it can thus be seen that liquid water is evaporated in order to cool a medium to be cooled. 
     Unlike the temperature level in conventional evaporation plants, the medium to be cooled can be cooled to very low temperatures of, for example, from about 10° C. to about 15° C. The amount of water required for this is very small because of the evaporation of the water. In addition, recirculation of heated water to a water source can be avoided because of the evaporation of the water. 
     LIST OF REFERENCE NUMERALS 
     
         
           100  Cooling apparatus 
           102  Heat exchanger 
           104  Evaporation apparatus 
           106  Water feed apparatus 
           108  Vacuum apparatus 
           110  Subatmospheric pressure side 
           112  Evaporation space 
           114  Loading apparatus 
           116  Loading space 
           118  Transport apparatus 
           120  Unloading space 
           122  Unloading apparatus 
           124  Transport direction 
           126  Lock device 
           128  High-pressure side 
           130  Heat exchanger 
           132  External heat source 
           134  Surroundings 
           136  Flushing apparatus 
           138  Degassing apparatus 
           140  Throttle valve 
           142  Extraction apparatus 
           144  Absorption medium circuit 
           146  Water transport section