Patent Publication Number: US-2021190335-A1

Title: Dehumidifier with thermosiphon arrangement

Description:
FIELD OF THE INVENTION 
     The present invention relates to a dehumidifier for dehumidifying ambient air in an airstream from an inlet to an exhaust from an outlet in a housing. The dehumidifier comprises an evaporator having an evaporator downstream face and an evaporator upstream face; and downstream from the evaporator a condenser having a condenser downstream face and a condenser upstream face. The dehumidifier further has a thermosiphon arrangement configured to be arranged with a thermosiphon evaporator part upstream from the evaporator and a thermosiphon condenser part upstream from the condenser and downstream from the evaporator. 
     BACKGROUND OF THE INVENTION 
     Dehumidifiers are generally known in the art. In particular dehumidifiers comprising an active evaporator and condenser arranged in a housing to dehumidify ambient air. 
     Such dehumidifiers are typically designed or dimensioned to operate according to certain ambient conditions. 
     FR2672970 describes a dehumidifier which has an evaporator upstream from a condenser, a thermosiphon evaporator part upstream from the evaporator and a thermosiphon condenser part downstream from the evaporator and upstream from the condenser. The thermosiphon evaporator part is connected to the thermosiphon condenser part via a single tube, having a significant part of the whole tube external from both thermosiphon parts and, thus, increases the size of the entire installation. Furthermore, the tube parts external to either thermosiphon part are neither heated nor cooled and thus do not contribute to the purpose of the thermosiphon as such, but the external tube parts increase the overall weight and complexity of the installation. 
     OBJECT OF THE INVENTION 
     It is an objective to improve effectiveness of a dehumidifier at a certain operational condition or over a range of operational conditions. 
     It is an objective to decrease the size and/or weight of the active evaporator and condenser parts of a dehumidifier. 
     It is an objective to increase the range of operational ambient conditions whilst maintaining or even reduce the size and power consumption of the active part. 
     It is a further objective to reduce complexity of a dehumidifier. 
     DESCRIPTION OF THE INVENTION 
     An object is achieved by a dehumidifier for dehumidifying ambient air in an airstream from an inlet to an exhaust from an outlet in a housing. The dehumidifier comprises an evaporator having an evaporator downstream face and an evaporator upstream face; and downstream from the evaporator a condenser having a condenser downstream face and a condenser upstream face. 
     The condenser may be at a higher gravitational level than the evaporator. It is understood that the housing is configured to be positioned in a top-down orientation relative to gravity. 
     The evaporator and the condenser may be interconnected and arrangements are generally known in the art and a person skilled in the art will be able to construct various implementations of the evaporator and condenser. In the housing walls, insulation or alike separators may be installed to establish the airflow so that the airflow is from the inlet to the outlet via the evaporator and the condenser. 
     The dehumidifier further has a thermosiphon arrangement configured to be arranged with a thermosiphon evaporator part upstream from the evaporator and a thermosiphon condenser part upstream from the condenser and downstream from the evaporator. 
     The evaporator and condenser may be considered active and driven by active circulation of a refrigerant and by a compressor. The thermosiphon may be considered passive. 
     A dehumidifier having a thermosiphon arrangement is thus more effective and allows for reduction in size, power consumption or both of the active evaporator and condenser. 
     Furthermore, the thermosiphon arrangement evaporator part may pre-condition the thermal conditions of the airstream before interacting with the evaporator and thus reduce span of thermal conditions necessary for the evaporator to operate under. 
     Likewise the thermosiphon condenser part may pre-condition the thermal conditions of the airstream before interacting with the condenser and thus reduce the span of thermal conditions necessary for the condenser to operate under. 
     The reduction of span of operational conditions may allow for simpler control or regulation systems and thus overall reduce complexity. 
     Thus the evaporator is sandwiched between the thermosiphon arrangement so that the evaporator is preceded by a thermosiphon evaporator part and followed by a thermosiphon condenser part in the airstream. Again walls, insulation and separators may be installed to ensure that the airflow passes the thermosiphon arrangement. 
     In an embodiment the thermosiphon arrangement has a thermosiphon evaporator part having a first header and a second header and in between a fluid communicator arrangement. The fluid communicator arrangement may be with multiple MPE-tubes optionally with fins in between. The thermosiphon condenser part may be constructed using the same components. The thermosiphon evaporator part may be interconnected with the thermosiphon condenser part. 
     In an embodiment the condenser header of the thermosiphon condenser part may be in fluid connection with the condenser header of the thermosiphon evaporator part and the evaporator header of the thermosiphon condenser part may be in fluid connection with the evaporator header of the thermosiphon evaporator part. The condenser headers are arranged above the evaporator headers thus creating a circulating flow of a refrigerant during operation. 
     In an embodiment the condenser thermosiphon part is in fluid communication with the evaporator thermosiphon part by the evaporator header of the condenser thermosiphon part being connected to the condenser header of the evaporator part. Again a person skilled in the art will be able to position the respective headers relative to each other so as to create the effects of a thermosiphon. 
     The respective evaporator and condenser thermosiphon parts may comprise a thermosiphon block configured for a refrigerant to circulate between a first header, such as an evaporator header, and a second header, such as condenser header, interconnected with a fluid communicator arrangement. The communicator arrangement may comprise multiple MPE-tubes with fins in-between. 
     In an embodiment, the thermosiphon arrangement comprises a thermosiphon block configured for a refrigerant to communicate between a first header, such as an evaporator header, and a second header, such as a condenser header. The first and second headers are connected with a fluid communicator arrangement and the thermosiphon block is sealed and contains the refrigerant. 
     By using a sealed thermosiphon block a particular compact dehumidifier is achieved. The thermosiphon block results in a great reduction or elimination of additional piping or fluid connections. The thermosiphon block is furthermore simple and reduces requirements of brazing. Furthermore, a thermosiphon block is easy to clean or maintain and even to replace, since a dirty or defect block can easily slide out and back in. 
     Thus in effect, a thermosiphon block, in particular the thermosiphon evaporator part of the thermosiphon block may serve as a filter for the evaporator. Thereby the combined effect is extending operational time at or within certain effectiveness requirements. 
     The communicator arrangement may be multiple tubes, such as MPE-tubes. There may be fins in-between the tubes. 
     In an embodiment of the fluid communicator arrangement, the thermosiphon block has a part that is a thermosiphon evaporator part having a thermosiphon evaporator part downstream face substantially facing the evaporator upstream face. 
     In an embodiment of the fluid communicator arrangement, the thermosiphon block has a part that is a thermosiphon condenser part having a thermosiphon condenser part downstream face substantially facing the condenser upstream face. 
     The faces may be substantially arranged equidistant to each other. The faces may be structurally close to each other. By close is understood that the thermosiphon evaporator part downstream face is arranged as close to the evaporator upstream face taking headers and frames into account. The faces may be substantially of the same area. The thermosiphon evaporator face may be larger than the face of the evaporator. 
     The thermosiphon evaporator part downstream face and the thermosiphon condenser part upstream face is the same face of the thermosiphon block. The opposite face of the thermosiphon block is the thermosiphon evaporator part upstream face and the thermosiphon condenser part downstream face. 
     The evaporator face and the condenser face projection onto the faces of the thermosiphon block may define the evaporator and condenser part of the thermosiphon block. There may be a zone in-between, which zone will be a thermal transition zone or an adiabatic zone. 
     The faces may be provided arranged to create or result in an adiabatic zone that is as small as possible. 
     There may be walls, insulation or alike separation means arranged to further separate the evaporator part from the condenser part. 
     In an aspect of the dehumidifier as having a first thermosiphon arrangement as disclosed there, in addition to the first thermosiphon arrangement a dehumidifier may further comprise a second thermosiphon arrangement. This second thermosiphon arrangement may be arranged with second thermosiphon evaporator part downstream from first thermosiphon evaporator part, i.e. between the first thermosiphon evaporator part and the evaporator, and a second thermosiphon condenser part upstream from the first thermosiphon condenser part/side, i.e. between the evaporator and the first thermosiphon condenser part/side. 
     Besides an incremental effect for a certain thermal condition of the airstream, say at certain temperature and relative humidity, e.g. T28° C. and RH60%, an arrangement with two thermosiphon arrangements have shown to further and unexpectedly to improve effectiveness at an additional thermal condition, e.g. T20° C. and RH50%. 
     In example, having a dehumidifier in a configuration comprising only the active evaporator and condenser having an operational efficiency indexed  100  at particular operating point of ambient conditions (e.g. [T10° C.,RH50%], . . . [T20° C.,RH50%], . . . , [T28° C.,RH60%], . . . [T35° C.,RH80%]). 
     Then for [T28° C.,RH60%] using only one thermosiphon arrangement results in an index  141 ; and using two thermosiphon arrangements result in an index  146 . 
     However, for [T20° C.,RH50%] using only one thermosiphon arrangement results in an index  138 ; but using two thermosiphon arrangements result in an index  152 . 
     Hence using two thermosiphon arrangements has resulted in not only greater, even incremental, but also reduced relative span of effectiveness over a range of thermal conditions. Thus two thermosiphon arrangements allow for a simpler or more standardised configuration of the active evaporator and condenser arrangement to be used. 
     Thus using two thermosiphon arrangements improves the overall operational range of ambient conditions in which the dehumidifier will work using the same configuration of the active evaporator and condenser configuration. 
     In an aspect of the dehumidifier with two thermosiphon arrangements, the first thermosiphon arrangement is a first thermosiphon block and the second thermosiphon arrangement is a second thermosiphon block. 
     The thermosiphon block being sealed and in nature simple and having a flat design form allows for two thermosiphon arrangements to easily be implemented to achieve the additional advantages described whilst maintaining a compact, e.g. flat design. 
     The two thermosiphon blocks may be sandwiched and aligned. They may be stacked. The two thermosiphon blocks may be identical. Each thermosiphon blocks may have connections to be stacked. The two thermosiphon blocks may form a common block as the thermosiphon arrangement. 
     A person skilled in the art will configure the thermosiphon blocks with the condenser headers in an upper part of the housing and the evaporator headers in a lower part of the housing. The thermosiphon blocks may be tilted in the housing creating a volume for the respective evaporator and condenser. 
     In an embodiment the first thermosiphon block and the second thermosiphon block are sandwiched with
         the first thermosiphon evaporator part downstream face substantially facing the second thermosiphon evaporator part upstream face;   the first thermosiphon condenser part upstream face substantially facing the second thermosiphon condenser part downstream face;   the second thermosiphon evaporator part downstream face substantially facing the evaporator upstream face; and   the first thermosiphon condenser part downstream face substantially facing the condenser upstream face.       

     In general the dehumidifier as disclosed with a first thermosiphon arrangement may be constructed as a dehumidifier, which in addition to the first thermosiphon arrangement further comprising N−1 thermosiphon arrangements. For i=2 to N; each i&#39;th thermosiphon arrangement arranged with an i&#39;th thermosiphon evaporator parte downstream from the i−1 thermosiphon evaporator part and an i&#39;th thermosiphon condenser part upstream from the i−1 thermosiphon condenser part. 
     That is a dehumidifier having an evaporator and a condenser and in total N thermosiphon arrangements. 
     Such dehumidifier has the first thermosiphon arrangement as a first thermosiphon block and the Nth thermosiphon arrangement is an Nth thermosiphon block. 
     In an embodiment, all N thermosiphon blocks are sandwiched. Such N-thermosiphon block arrangement or common block has the (i−1)&#39;th thermosiphon evaporator part downstream face substantially facing the i&#39;th thermosiphon evaporator part upstream face; the (i−1)&#39;th thermosiphon condenser part upstream face substantially facing the i&#39;th thermosiphon condenser part downstream face; the Nth thermosiphon evaporator part downstream face substantially facing the evaporator upstream face; and the first thermosiphon evaporator part downstream face substantially facing the condenser upstream face. 
     The thermosiphon arrangements, including a thermosiphon block, may use a refrigerant readily available. A refrigerant may be chosen amongst refrigerants such as: R 1234 ZE, R 1234 YF, R 1234 A, R 290, R 32, R 152 A, R 444 B, R 444 A, R 407 C, R 410 A, R 454 C, Water, Water with Ethanol, Ethanol, Water with isopropanol, Water with glycol, or Isopropanol. The list is not complete and equivalents may be used. Likewise mixtures and dilutions may be used. 
     In various aspects the dehumidifier may comprise a separator separating the evaporator parts from the condenser parts and configured to guide the airstream from the evaporators to the condenser in the housing. 
     As outlined the separator may be a wall or a wall arrangement. Parts may be insulated to better define the respective evaporator and condenser parts as will be apparent from the figures the walls may be easily installed or modified starting from the suggested embodiments. A person skilled in the art starting from the suggested embodiments will find it natural to perform some experimentation to optimise the airstream and to reduce pressure drops. 
     Finally, a person skilled in the art will be able to implement collectors, drains or other means of handling water extracted during dehumidification. 
    
    
     
       DESCRIPTION OF THE DRAWING 
       Embodiments of the invention will be described in the figures, whereon: 
         FIG. 1  illustrates a known dehumidifier; 
         FIG. 2  illustrates a dehumidifier comprising a thermosiphon arrangement; 
         FIG. 3  illustrates a dehumidifier comprising two thermosiphon arrangements; 
         FIG. 4  illustrates a comparison of the previous three dehumidifiers; 
         FIG. 5  illustrates a thermosiphon arrangement configured to circulate a refrigerant between a condenser and an evaporator; 
         FIG. 6  illustrates an embodiment of a thermosiphon arrangement as a thermosiphon block; 
         FIG. 7  illustrates an embodiment of a thermosiphon arrangement; 
         FIG. 8  illustrates a dehumidifier comprising a thermosiphon arrangement based on a thermosiphon block; 
         FIG. 9  illustrates a dehumidifier comprising two thermosiphon blocks as the thermosiphons arrangement; 
         FIG. 10  illustrates a dehumidifier comprising N thermosiphon blocks a the thermosiphons arrangement; 
         FIG. 11  illustrates a dehumidifier comprising a bent thermosiphons arrangement; and 
         FIG. 12  illustrates a dehumidifier projected onto an airstream; 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       
     
       
         
           
               
               
               
             
               
                   
                   
               
               
                   
                 No 
                 Item 
               
               
                   
                   
               
             
            
               
                   
                  10 
                 Ambient air 
               
               
                   
                  20 
                 Exhaust 
               
               
                   
                 100 
                 Dehumidifier 
               
               
                   
                 110 
                 Inlet 
               
               
                   
                 114 
                 Upstream 
               
               
                   
                 115 
                 Airstream 
               
               
                   
                 116 
                 Downstream 
               
               
                   
                 120 
                 Outlet 
               
               
                   
                 130 
                 Housing 
               
               
                   
                 140 
                 Separator 
               
               
                   
                 E - 210 
                 Evaporator 
               
               
                   
                 211 
                 Evaporator Downstream face 
               
               
                   
                 212 
                 Evaporator Upstream face 
               
               
                   
                 C - 220 
                 Condenser 
               
               
                   
                 221 
                 Condenser Downstream face 
               
               
                   
                 222 
                 Condenser Upstream face 
               
               
                   
                 300 
                 Thermosiphon arrangement 
               
               
                   
                 302 
                 Refrigerant 
               
               
                   
                 TS-E - 310 
                 Thermosiphon evaporator part 
               
               
                   
                 311 
                 Thermosiphon evaporator part downstream face 
               
               
                   
                 312 
                 Thermosiphon evaporator part upstream face 
               
               
                   
                 TS-C - 320 
                 Thermosiphon condenser part 
               
               
                   
                 321 
                 Thermosiphon condenser part downstream face 
               
               
                   
                 322 
                 Thermosiphon condenser part upstream face 
               
               
                   
                 330 
                 Fluid connection 
               
               
                   
                 400 
                 Thermosiphon block 
               
               
                   
                 410 
                 Header 
               
               
                   
                 411 
                 First header - evaporator part header 
               
               
                   
                 412 
                 Second header - condenser part header 
               
               
                   
                 420 
                 Fluid communicator arrangement 
               
               
                   
                 440 
                 Adiabatic zone 
               
               
                   
                   
               
            
           
         
       
     
       FIG. 1  illustrates a known dehumidifier  100 . The dehumidifier  100  has a housing  130  with an inlet  110  for intake of ambient air  10  and an outlet  120  for exhaust  20  of the air in the dehumidifier  100 . 
     Airflow  115  is defined by the ambient air  10  flowing through the dehumidifier  100  from the inlet  110  towards the outlet  120 . The airflow  115  defines two directions upstream  114  and downstream  116 . Upstream  114  faces the opposite direction of the airflow  115 . Downstream  116  faces the same direction as the airflow  115 . 
     The dehumidifier  100  may have one or more walls (not shown) to control the airflow  115  such that the pressure loss through the dehumidifier  100  is as low as possible. The skilled person would know how to position the one or more walls. 
     The dehumidifier  100  has along the airstream  115 , in the following order, an evaporator E- 210  and a condenser C- 220 . The condenser C- 220  is positioned at a higher gravitational level of the evaporator E- 210 . 
     The evaporator E- 210  will actively cool the ambient air  10  below the dew point and the condenser C- 220  will afterwards actively heat the dehumidified air. The evaporator E- 210  and the condenser C- 220  are interconnected by first a fluid connection  330  and, optional, a second fluid connection  330 ′, thereby creating a circuit such that a refrigerant  302  may flow between the elements. The skilled person would know that a not shown compressor is part of the circuit. 
     The circuit are not shown in the other figures, but the skilled person would know that the circuit are present in the systems the figures represent. 
     The evaporator E- 210  has an evaporator downstream face  211  facing the downstream  116  and an evaporator upstream face  212  facing the upstream  114 . The evaporator upstream face  212  substantially faces the inlet  110 . 
     The condenser C- 220  has a condenser downstream face  221  facing the downstream  116  and a condenser upstream face  222  facing the upstream  114 . The condenser downstream face  221  substantially faces the outlet  120 . 
     The evaporator downstream face  211  substantially faces the condenser upstream face  222 . 
       FIG. 2  illustrates a dehumidifier  100  comprising a thermosiphon arrangement  300 . The dehumidifier  100  has a housing  130  with an inlet  110  for intake of ambient air  10  and an outlet  120  for exhaust  20  of the air in the dehumidifier  100 . 
     Airflow  115  is defined by the ambient air  10  flowing through the dehumidifier  100  from the inlet  110  towards the outlet  120 . The airflow  115  defines two directions upstream  114  and downstream  116 . Upstream  114  faces the opposite direction of the airflow  115 . Downstream  116  faces the same direction as the airflow  115 . 
     The dehumidifier  100  may have one or more walls (not shown) to control the airflow  115  such that the pressure loss through the dehumidifier  100  is as low as possible. The skilled person would know how to position the one or more walls. 
     The dehumidifier  100  has along the airstream  115  an evaporator E- 210  and a condenser C- 220 . Although not shown, the evaporator E- 210  and the condenser C- 220  are interconnected, such that a refrigerant  302  may flow. 
     The evaporator E- 210  has an evaporator downstream face  211  facing the downstream  116  and an evaporator upstream face  212  facing the upstream  114 . 
     The condenser C- 220  has a condenser downstream face  221  facing the downstream  116  and a condenser upstream face  222  facing the upstream  114 . 
     The thermosiphon arrangement  300  comprises a thermosiphon evaporator part TS-E- 310  and a thermosiphon condenser part TS-C- 320 . The thermosiphon evaporator part TS-E- 310  and the thermosiphon condenser part TS-C- 320  are interconnected by first a fluid connection  330  and, optional, a second fluid connection  330 ′, thereby creating a circuit such that a refrigerant  302  may flow between the elements. 
     The thermosiphon evaporator part TS-E- 310  has a thermosiphon evaporator part downstream face  311  facing downstream  116  and a thermosiphon evaporator part upstream face  312  facing upstream  114 . 
     The thermosiphon condenser part TS-C- 320  has a thermosiphon condenser part downstream face  321  facing downstream  116  and a thermosiphon condenser part upstream face  322  facing upstream  114 . 
     The evaporators  210 ,  310  and condensers  220 ,  320  are positioned as described below. It is seen that the thermosiphon evaporator part upstream face  312  substantially faces the inlet  110 . 
     It is seen that the thermosiphon evaporator part downstream face  311  substantially faces the evaporator upstream face  212 . 
     It is seen that the evaporator downstream face  211  substantially faces the thermosiphon condenser part upstream face  322 . 
     It is seen that the thermosiphon condenser part downstream face  321  substantially faces the condenser upstream face  222 . 
     It is seen that the condenser downstream face  221  substantially faces the outlet  120 . 
     The evaporators  210 ,  310  and condensers  220 ,  320  are aligned such that the pressure loss through the dehumidifier  100  is kept at a minimum as pressure loss lowers the efficiency of the dehumidifier  100 . 
     The thermosiphon arrangement  300  is a passive element. The thermosiphon evaporator part TS-E- 310  will lower the temperature of the ambient air  10 . The air temperature will be closer to the dew point and thus the work needed to be performed by the evaporator E- 210  will be lower. The air will afterwards be heated by the thermosiphon condenser part TS-C- 320 , thereby ensuring flow of the refrigerant  302 . Afterwards the active condenser C- 220  will heat the dehumidified air. 
     Tests have shown that the dehumidifier  100  comprising the thermosiphon arrangement  300  is more efficient relative to the standard dehumidifier  100  disclosed in  FIG. 1 . A comparison between the two embodiments is shown in  FIG. 4 . 
       FIG. 3  illustrates a dehumidifier  100  comprising two thermosiphon arrangements  300 I,  300 II. 
     The dehumidifier  100  has a housing  130  with an inlet  110  for intake of ambient air  10  and an outlet  120  for exhaust  20  of the air in the dehumidifier  100 . 
     Airflow  115  is defined by the ambient air  10  flowing through the dehumidifier  100  from the inlet  110  towards the outlet  120 . The airflow  115  defines two directions upstream  114  and downstream  116 . Upstream  114  faces the opposite direction of the airflow  115 . Downstream  116  faces the same direction as the airflow  115 . 
     The dehumidifier  100  may have one or more walls (not shown) to control the airflow  115  such that the pressure loss through the dehumidifier  100  is as low as possible. The skilled person would know how to position the one or more walls. 
     The dehumidifier  100  has along the airstream  115  an evaporator E- 210  and a condenser C- 220 . Although not shown, the evaporator E- 210  and the condenser C- 220  are interconnected, such that a refrigerant  302  may flow. 
     The evaporator E- 210  has an evaporator downstream face  211  facing the downstream  116  and an evaporator upstream face  212  facing the upstream  114 . 
     The condenser C- 220  has a condenser downstream face  221  facing the downstream  116  and a condenser upstream face  222  facing the upstream  114 . 
     Each thermosiphon arrangement  300 I,  300 II comprises a thermosiphon evaporator part TS-E- 310 I, TS-E- 310 II and a thermosiphon condenser part TS-C- 320 I, TS-C- 320 II. The thermosiphon evaporator part TS-E- 310 I, TS-E- 310 II and the thermosiphon condenser part TS-C- 320 I, TS-C- 320 II are interconnected by a fluid connection  330 I,  330 II and, optional, a second fluid connection  330 I′,  330 II′, thereby creating a circuit such that a refrigerant  302  may flow between the elements. 
     Each thermosiphon evaporator part TS-E- 310 I, TS-E- 310 II has a thermosiphon evaporator part downstream face  311 I,  311 II facing downstream  116  and a thermosiphon evaporator part upstream face  312 I,  312 II facing upstream  114 . 
     Each thermosiphon condenser part TS-C- 320 I, TS-C- 320 II has a thermosiphon condenser part downstream face  321 I,  321 II facing downstream  116  and a thermosiphon condenser part upstream face  322 I,  322 II facing upstream  114 . 
     The evaporators  210 ,  310 I,  310 II and condensers  220 ,  320 I,  320 II are positioned as described below. 
     It is seen that the thermosiphon evaporator part upstream face  312 I substantially faces the inlet  110 . 
     It is seen that the thermosiphon evaporator part downstream face  311 I substantially faces thermosiphon evaporator part upstream face  312 II. 
     It is seen that the thermosiphon evaporator part downstream face  311 II substantially faces the evaporator upstream face  212 . 
     It is seen that the evaporator downstream face  211  substantially faces the thermosiphon condenser part upstream face  322 II. 
     It is seen that the thermosiphon condenser part downstream face  321 II substantially faces thermosiphon condenser part upstream face  322 I. 
     It is seen that the thermosiphon condenser part downstream face  321 I substantially faces the condenser upstream face  222 . 
     It is seen that the condenser downstream face  221  substantially faces the outlet  120 . 
     The evaporators  210 ,  310 I,  310 II and condensers  220 ,  320 I,  320 II are aligned such that the pressure loss through the dehumidifier  100  is kept at a minimum as pressure loss lowers the efficiency of the dehumidifier  100 . 
     The thermosiphon arrangements  300 I,  300 II are both passive elements. The thermosiphon evaporator parts TS-E- 310 I, TS-E- 310 II will lower the temperature of the ambient air  10 . The air temperature will be closer to the dew point and thus the work needed to be performed by the evaporator E- 210  will be lower. The air will afterwards be heated by the thermosiphon condenser parts TS-C- 320 I, TS-C- 320 II, thereby ensuring flow of the refrigerant  302 . Afterwards the active condenser C- 220  will heat the dehumidified air. 
     Tests have shown that the dehumidifier  100  comprising the two thermosiphon arrangements  300  is more efficient relative to the standard dehumidifier  100  disclosed in  FIG. 1 . 
     Tests have also shown the dehumidifier  100  comprising the two thermosiphon arrangements  300  is more efficient than the dehumidifier  100  disclosed in  FIG. 2  in a broad range of temperature and relative humidity. 
     A comparison between the different embodiments is shown in  FIG. 4 . 
       FIG. 4  illustrates a comparison of the previous three dehumidifiers  100 PA ( FIG. 1 ),  100 - 1 TS ( FIG. 2 ) and  100 - 2 TS ( FIG. 3 ). 
       FIG. 4  discloses a graph having a first axis showing the various measuring points. The dehumidifiers  100 PA,  100 - 1 TS and  100 - 2 TS have been measured at the temperatures 10° C., 20° C. 28° C. and 35° C. Each temperature point has been measured with a relative humidity (RH) of RH50%, RH60% and RH80%. 
     The second axis represents the amount water volume per kWh spent. The prior art dehumidifier  100 PA has been used as a reference and has been set to 100% at each test point. 
     It is the industry standard to compare dehumidifiers at the point [T28° C., RH60%]. The dehumidifier  100 - 1 TS shows an efficiency increase of 43% relative to the prior art. The dehumidifier  100 - 2 TS increases the efficiency by only a few percentage points relative to the dehumidifier  100 - 1 TS at the point [T28° C., RH60%]. 
     However, at the points [T28° C., RH50%] and [T28° C., RH80%] the difference in efficiency between the two dehumidifiers is larger. 
     The dehumidifier  100 - 2 TS is more efficient than the dehumidifier  100 - 1 TS at all points, with the exception of point [10° C., RH80%]. The difference in efficiency is largest at point [20° C., RH50%]. 
       FIG. 5  illustrates a thermosiphon arrangement  300  configured to circulate a refrigerant  302  between a condenser TS-C- 320  and an evaporator TS-E- 310 . 
     The thermosiphon condenser part TS-C- 320  has two headers  410 ,  410 ′ interconnected by a fluid communications arrangement  420 , where one header  410 ′ is at a higher gravitational level. There are means for guiding gaseous refrigerant to the condenser TS-C- 320 . 
     The thermosiphon evaporator part TS-E- 310  has two headers  410 ″,  410 ′″ interconnected by a fluid communications arrangement  420 , where one header  410 ′″ is at a higher gravitational level. 
     The thermosiphon evaporator part TS-E and the thermosiphon condenser part TS-C are shown to have headers  410  connected via fluid connections  330  as shown. 
     The fluid communications arrangements  420  are shown with MPEs with fins to cover an area as large as possible to efficiently convert heat from the airstream  115  indicated to exemplify the thermosiphon arrangement  300  during intended operation. 
       FIG. 6  illustrates an embodiment of a thermosiphon arrangement  300  as a thermosiphon block  400 . 
       FIG. 6A  shows a thermosiphon block  400  configured for a refrigerant  302  to circulate between a first header  411 , here working as an evaporator header, and a second header  412 , here working as a condenser header. The first and second headers  411 ,  412  are interconnected with a fluid communicator arrangement  420  here comprising multiple MPE-tubes with fins in-between. The thermosiphon block  400  is sealed and contains a refrigerant  302 . The thermosiphon block  400  is here shown with connection means  430  enabling installation in a top-down orientation making the first header  411  install at a lower gravitational level than the second header  412  and thus when installed as suggested in the following figures resulting in the first header  411  being an evaporator header and the second header  412  being a condenser header. Installing the thermosiphon block in a housing with an evaporator and a condenser as will be described in the subsequent figures will define the thermosiphon evaporator part TS-E- 310  and the thermosiphon condenser part TS-C- 320 . In-between there may or will be an adiabatic zone  440  with an extent that is determined by the actual placement of the faces. 
       FIG. 6B  shows the thermosiphon block  400  from  FIG. 6A  with a partition plate or separator  140  installed between the first and second headers  411 , 412 . The separator  140  may be part of a wall to be fitted to guide the airstream when installed. For illustrative purpose an airstream  115  is shown to exemplify the working during intended use. The shown embodiment in this orientation is a vertical thermosiphon block where the transfer of heat is essentially in the vertical direction during operation. 
     The airstream  115  will penetrate the thermosiphon evaporator part TS-E- 310  from a thermosiphon evaporator part upstream face  312 , circulate and penetrate the thermosiphon condenser part TS-C- 320  from a thermosiphon condenser part upstream face  322 . 
       FIG. 7  illustrates an embodiment of a thermosiphon arrangement  300 . The embodiment shows two modified thermosiphon blocks  400 . One block as a condenser thermosiphon block  400 C operating as the thermosiphon condenser part TS-C- 320  and another as an evaporator thermosiphon block  400 E operating as the thermosiphon evaporator part TS-E- 310 . The two blocks are modified by the first header  411  (the lower and evaporator header) of the thermosiphon condenser part TS-C- 320  being in fluid communication with the second header (the upper and condenser header) of the thermosiphon evaporator part TS-E- 310  via a fluid connection. 
     An airstream  115  as in intended operation is shown. The airstream  115  will penetrate the thermosiphon evaporator part TS-E- 310  from a thermosiphon evaporator part upstream face  312 , circulate and penetrate the thermosiphon condenser part TS-C- 310  from a thermosiphon condenser part upstream face  322 . 
       FIG. 8  illustrates a dehumidifier  100  comprising a different embodiment of a thermosiphon arrangement  300 . 
     The dehumidifier  100  has a housing  130  with an inlet  110  for intake of ambient air  10  and an outlet  120  for exhaust  20  of the air in the dehumidifier  100 . 
     Airflow  115  is defined by the ambient air  10  flowing through the dehumidifier  100  from the inlet  110  towards the outlet  120 . The airflow  115  defines two directions upstream  114  and downstream  116 . Upstream  114  faces the opposite direction of the airflow  115 . Downstream  116  faces the same direction as the airflow  115 . 
     The dehumidifier  100  may have one or more walls (not shown) to control the airflow  115  such that the pressure loss through the dehumidifier  100  is as low as possible. The skilled person would know how to position the one or more walls. 
     The dehumidifier  100  has along the airstream  115 , an evaporator E- 210  and a condenser C- 220 . Although not shown, the evaporator E- 210  and the condenser C- 220  are interconnected, such that a refrigerant  302  may flow. 
     The evaporator E- 210  has an evaporator downstream face  211  facing the downstream  116  and an evaporator upstream face  212  facing the upstream  114 . 
     The condenser C- 220  has a condenser downstream face  221  facing the downstream  116  and a condenser upstream face  222  facing the upstream  114 . 
     The thermosiphon arrangement  300  comprises a thermosiphon block  400  having two headers  410 . The first header  411  is the evaporator part header  411  and the second header  412  is the condenser part header  412 . The headers  410  are interconnected by a fluid communicator arrangement  420  for liquid communications of a refrigerant  302 . 
     The thermosiphon block  400  is divided by at least one separator  140  into a thermosiphon evaporator part TS-E- 310  and a thermosiphon condenser part TS-C- 320 . 
     The thermosiphon evaporator part TS-E- 310  has a thermosiphon evaporator part downstream face  311  facing downstream  116  and a thermosiphon evaporator part upstream face  312  facing upstream  114 . 
     The thermosiphon condenser part TS-C- 320  has a thermosiphon condenser part downstream face  321  facing downstream  116  and a thermosiphon condenser part upstream face  322  facing upstream  114 . 
     The evaporators  210 ,  310  and condensers  220 ,  320  are positioned as described below. It is seen that the thermosiphon evaporator part upstream face  312  substantially faces the inlet  110 . 
     It is seen that the thermosiphon evaporator part downstream face  311  substantially faces the evaporator upstream face  212 . 
     It is seen that the evaporator downstream face  211  substantially faces the thermosiphon condenser part upstream face  322 . 
     It is seen that the thermosiphon condenser part downstream face  321  substantially faces the condenser upstream face  222 . 
     It is seen that the condenser downstream face  221  substantially faces the outlet  120 . 
     The evaporators  210 ,  310  and condensers  220 ,  320  are aligned such that the pressure loss through the dehumidifier  100  is kept at a minimum as pressure loss lowers the efficiency of the dehumidifier  100 . 
     The thermosiphon arrangement  300  is a passive element. The thermosiphon evaporator part TS-E- 310  will lower the temperature of the ambient air  10 . The air temperature will be closer to the dew point and thus the work needed to be performed by the evaporator E- 210  will be lower. The air will afterwards be heated by the thermosiphon condenser part TS-C- 320 , thereby ensuring flow of the refrigerant  302 . Afterwards the active condenser C- 220  will heat the dehumidified air. 
       FIG. 9  illustrates a dehumidifier  100  comprising two thermosiphon arrangements  300 I,  300 II. 
     The dehumidifier  100  has a housing  130  with an inlet  110  for intake of ambient air  10  and an outlet  120  for exhaust  20  of the air in the dehumidifier  100 . 
     Airflow  115  is defined by the ambient air  10  flowing through the dehumidifier  100  from the inlet  110  towards the outlet  120 . The airflow  115  defines two directions upstream  114  and downstream  116 . Upstream  114  faces the opposite direction of the airflow  115 . Downstream  116  faces the same direction as the airflow  115 . 
     The dehumidifier  100  may have one or more walls (not shown) to control the airflow  115  such that the pressure loss through the dehumidifier  100  is as low as possible. The skilled person would know how to position the one or more walls. 
     The dehumidifier  100  has along the airstream  115 , an evaporator E- 210  and a condenser C- 220 . Although not shown, the evaporator E- 210  and the condenser C- 220  are interconnected, such that a refrigerant  302  may flow. 
     The evaporator E- 210  has an evaporator downstream face  211  facing the downstream  116  and an evaporator upstream face  212  facing the upstream  114 . 
     The condenser C- 220  has a condenser downstream face  221  facing the downstream  116  and a condenser upstream face  222  facing the upstream  114 . 
     Each thermosiphon arrangement  300 I, II comprises a thermosiphon block  400 I,  400 II having a first header  411 I,  411 II being the evaporator part header  411 I,  411 II and a second header  412 I,  412 II being the condenser part header  412 I,  412 II. The header  411 I,  412 I and  411 II,  412 II are interconnected by a fluid communicator arrangement  420 I,  420 II for liquid communications of a refrigerant  302 . 
     Each thermosiphon block  400 I,  400 II is divided by at least one separator  140  into a thermosiphon evaporator part TS-E- 310 I, TS-E- 310 II and a thermosiphon condenser part TS-C- 320 I, TS-C- 320 II. 
     Each thermosiphon evaporator part TS-E- 310 I, TS-E- 310 II has a thermosiphon evaporator part downstream face  311 I,  311 II facing downstream  116  and a thermosiphon evaporator part upstream face  312 I,  312 II facing upstream  114 . 
     Each thermosiphon condenser part TS-C- 320 I, TS-C- 320 II has a thermosiphon condenser part downstream face  321 I,  321 II facing downstream  116  and a thermosiphon condenser part upstream face  322 I,  322 II facing upstream  114 . 
     The evaporators  210 ,  310 I,  310 II and condensers  220 ,  320 I,  320 II are positioned as described below. 
     It is seen that the thermosiphon evaporator part upstream face  312 I substantially faces the inlet  110 . 
     It is seen that the thermosiphon evaporator part downstream face  311 I substantially faces the thermosiphon evaporator part upstream face  312 II. 
     It is seen that the thermosiphon evaporator part downstream face  311 II substantially faces the evaporator upstream face  212 . 
     It is seen that the evaporator downstream face  211  substantially faces the thermosiphon condenser part upstream face  322 II. 
     It is seen that the thermosiphon condenser part downstream face  321 II substantially faces the thermosiphon condenser part upstream face  322 I. 
     It is seen that the thermosiphon condenser part downstream face  321 I substantially faces the condenser upstream face  222 . 
     It is seen that the condenser downstream face  221  substantially faces the outlet  120 . 
     The evaporators  210 ,  310 I,  310 II and condensers  220 ,  320 I,  320 II are aligned such that the pressure loss through the dehumidifier  100  is kept at a minimum as pressure loss lowers the efficiency of the dehumidifier  100 . 
     The thermosiphon arrangements  300 I,  300 II are passive elements. The thermosiphon evaporator parts TS-E- 310 I, TS-E- 310 II will lower the temperature of the ambient air  10 . The air temperature will be closer to the dew point and thus the work needed to be performed by the evaporator E- 210  will be lower. The air will afterwards be heated by the thermosiphon condenser parts TS-C- 320 I, TS-C- 320 II, thereby ensuring flow of the refrigerant  302 . Afterwards the active condenser C- 220  will heat the dehumidified air. 
       FIG. 10  illustrates a dehumidifier comprising N thermosiphon blocks as thermosiphon arrangements  300 I . . . ,  300 N. 
     The dehumidifier  100  has a housing  130  with an inlet  110  for intake of ambient air  10  and an outlet  120  for exhaust  20  of the air in the dehumidifier  100 . 
     Airflow  115  is defined by the ambient air  10  flowing through the dehumidifier  100  from the inlet  110  towards the outlet  120 . The airflow  115  defines two directions upstream  114  and downstream  116 . Upstream  114  faces the opposite direction of the airflow  115 . Downstream  116  faces the same direction as the airflow  115 . 
     The dehumidifier  100  may have one or more walls (not shown) to control the airflow  115  such that the pressure loss through the dehumidifier  100  is as low as possible. The skilled person would know how to position the one or more walls. 
     The dehumidifier  100  has along the airstream  115 , an evaporator E- 210  and a condenser C- 220 . Although not shown, the evaporator E- 210  and the condenser C- 220  are interconnected, such that a refrigerant  302  may flow. 
     The evaporator E- 210  has an evaporator downstream face  211  facing the downstream  116  and an evaporator upstream face  212  facing the upstream  114 . 
     The condenser C- 220  has a condenser downstream face  221  facing the downstream  116  and a condenser upstream face  222  facing the upstream  114 . 
     Each thermosiphon arrangement  300 I, . . . ,  300 N comprises a thermosiphon block  400 I, . . . ,  400 N having a first header  411 I, . . . ,  411 N being the evaporator part header  411 I . . . ,  411 N and a second header  412 I, . . . ,  412 N being the condenser part header  412 I, . . . ,  412 N. The headers  411 I and  412 I, . . . ,  411 N and  412 N are interconnected by a fluid communicator arrangement  420 I, . . . ,  420 N for liquid communications of a refrigerant  302 . 
     Each thermosiphon block  400 I, . . . ,  400 N is divided by at least one separator  140  into a thermosiphon evaporator part TS-E- 310 I, TS-E- 310 N and a thermosiphon condenser part TS-C- 320 I, TS-C- 320 N. 
     Each thermosiphon evaporator part TS-E- 310 I, TS-E- 310 N has a thermosiphon evaporator part downstream face  311 I, . . . ,  311 N facing downstream  116  and a thermosiphon evaporator part upstream face  312 I, . . . ,  312 N. 
     Each thermosiphon condenser part TS-C- 320 I, TS-C- 320 N has a thermosiphon condenser part downstream face  321 I, . . . ,  321 N facing downstream  116  and a thermosiphon condenser part upstream face  322 I, . . . ,  322 N facing upstream  114 . 
     The evaporators  210 ,  310 I,  310   i (i=2 to (N−1)),  310 N and condensers  220 ,  320 I,  320   i (i=2 to (N−1)),  320 N are positioned as described below. 
     It is seen that the thermosiphon evaporator part upstream face  312 I substantially faces the inlet  110 . 
     It is seen that the thermosiphon evaporator part downstream face  311 I substantially faces the thermosiphon evaporator part upstream face  312 II. 
     It is seen that the thermosiphon evaporator part downstream face  311   i  substantially faces the thermosiphon evaporator part upstream face  312 ( i +1). 
     It is seen that the thermosiphon evaporator part downstream face  311 (N−1) substantially faces the thermosiphon evaporator part upstream face  312 N. 
     It is seen that the thermosiphon evaporator part downstream face  311 N substantially faces the evaporator upstream face  212 . 
     It is seen that the evaporator downstream face  211  substantially faces the thermosiphon condenser part upstream face  322 N. 
     It is seen that the thermosiphon condenser part downstream face  321 N substantially faces the thermosiphon condenser part upstream face  322 (N−1). 
     It is seen that the thermosiphon condenser part downstream face  321   i  substantially faces the thermosiphon condenser part upstream face  322 ( i −1). 
     It is seen that the thermosiphon condenser part downstream face  321 II substantially faces the thermosiphon condenser part upstream face  322 I. 
     It is seen that the thermosiphon condenser part downstream face  321 I substantially faces the condenser upstream face  222 . 
     It is seen that the condenser downstream face  221  substantially faces the outlet  120 . 
     The evaporators  210 ,  210 ,  310 I,  310   i (i=2 to (N−1)),  310 N and condensers  220 ,  320 I,  320   i (i=2 to (N−1)),  320 N are aligned such that the pressure loss through the dehumidifier  100  is kept at a minimum as pressure loss lowers the efficiency of the dehumidifier  100 . 
     The thermosiphon arrangements  300 I . . . ,  300 N are passive elements. The thermosiphon evaporator parts TS-E- 310 I . . . , TS-E- 310 N will lower the temperature of the ambient air  10 . The air temperature will be closer to the dew point and thus the work needed to be performed by the evaporator E- 210  will be lower. The air will afterwards be heated by the thermosiphon condenser parts TS-C- 320 I . . . , TS-C- 320 N, thereby ensuring flow of the refrigerant  302 . Afterwards the active condenser C- 220  will heat the dehumidified air. 
       FIG. 11  illustrates a dehumidifier  100  comprising a bent thermosiphon arrangement  300 . 
     The dehumidifier  100  has a housing  130  with an inlet  110  for intake of ambient air  10  and an outlet  120  for exhaust  20  of the air in the dehumidifier  100 . 
     Airflow  115  is defined by the ambient air  10  flowing through the dehumidifier  100  from the inlet  110  towards the outlet  120 . The airflow  115  defines two directions upstream  114  and downstream  116 . Upstream  114  faces the opposite direction of the airflow  115 . Downstream  116  faces the same direction as the airflow  115 . 
     The dehumidifier  100  may have one or more separators  140  to control the airflow  115  such that the pressure loss through the dehumidifier  100  is as low as possible. The skilled person would know how to position the one or more walls. 
     The dehumidifier  100  has along the airstream  115 , an evaporator E- 210  and a condenser C- 220 . Although not shown, the evaporator E- 210  and the condenser C- 220  are interconnected, such that a refrigerant  302  may flow. 
     The evaporator E- 210  has an evaporator downstream face  211  facing the downstream  116  and an evaporator upstream face  212  facing the upstream  114 . 
     The condenser C- 220  has a condenser downstream face  221  facing the downstream  116  and a condenser upstream face  222  facing the upstream  114 . 
     The thermosiphon arrangement  300  comprises a thermosiphon block  400  having two headers  410 . The first header  411  is the evaporator part header  411  and the second header  412  is the condenser part header  412 . The headers  410  are interconnected by a fluid communicator arrangement  420  for liquid communications of a refrigerant  302 . 
     In this embodiment the thermosiphon block  400  has a centrally positioned bent, thereby dividing the thermosiphon block  400  into a thermosiphon evaporator part TS-E- 310  and a thermosiphon condenser part TS-C- 320 . 
     The thermosiphon evaporator part TS-E- 310  has a thermosiphon evaporator part downstream face  311  facing downstream  116  and a thermosiphon evaporator part upstream face  312  facing upstream  114 . 
     The thermosiphon condenser part TS-C- 320  has a thermosiphon condenser part downstream face  321  facing downstream  116  and a thermosiphon condenser part upstream face  322  facing upstream  114 . 
     The evaporators  210 ,  310  and condensers  220 ,  320  are positioned as described below. 
     It is seen that the thermosiphon evaporator part upstream face  312  substantially faces the inlet  110 . 
     It is seen that the thermosiphon evaporator part downstream face  311  substantially faces the evaporator upstream face  212 . 
     It is seen that the evaporator downstream face  211  substantially faces the thermosiphon condenser part upstream face  322 . 
     It is seen that the thermosiphon condenser part downstream face  321  substantially faces the condenser upstream face  222 . 
     It is seen that the condenser downstream face  221  substantially faces the outlet  120 . 
     The evaporators  210 ,  310  and condensers  220 ,  320  are aligned such that the pressure loss through the dehumidifier  100  is kept at a minimum as pressure loss lowers the efficiency of the dehumidifier  100 . 
     The thermosiphon arrangement  300  is a passive element. The thermosiphon evaporator part TS-E- 310  will lower the temperature of the ambient air  10 . The air temperature will be closer to the dew point and thus the work needed to be performed by the evaporator E- 210  will be lower. The air will afterwards be heated by the thermosiphon condenser part TS-C- 320 , thereby ensuring flow of the refrigerant  302 . Afterwards the active condenser C- 220  will heat the dehumidified air. 
       FIG. 12  illustrates a dehumidifier  100  projected onto an airstream  115 . The airstream  115  is formed by the ambient air  10  entering the dehumidifier  100  at an inlet and exiting the dehumidifier at an outlet  120  as exhaust  20  being dehumidified air. 
     The airflow  115  defines two directions upstream  114  and downstream  116 . Upstream  114  faces the opposite direction of the airflow  115 . Downstream  116  faces the same direction as the airflow  115 . 
     The figure discloses in which order the airstream  115  passes evaporators and condensers. 
     The order is as followed:
         First the airstream passes the evaporators in the order of TS-E- 310 I, TS-E- 310   i  (i=2 to (N−1)), TS-E- 310 N, E- 210 .   Then the airstream passes the condensers in the order of TS-C- 320 N, TS-C- 320   i  (i=(N−1) to 2), TS-C- 320 I, C- 220 .       

     The different embodiments of the dehumidifiers  100  all follow the above mentioned order. The only difference being whether N=1 or N=2 or N equals another whole number.