Heat exchanger and metthod for manufacturing thereof

Abstract

A heat exchanger ( 1 ) comprising two sets of medium through-flow channels (P,S) through which two media can flow in heat-exchanging contact; walls ( 2 ) separating the channels; heat conducting fins ( 3 - 8 ) arranged on both sides of each wall ( 2 ), wherein a fin on the one side of a wall is in thermal contact with a similar contact surface of a fin on the other side of this wall; wherein the wall ( 2 ) are embodied as membrane and the fins ( 3 - 8 ) are embodied as heat transferring strips with a general wave shape and are provided with contact surfaces connected to the walls and main planes extending between two wall.

1 . Heat exchanger, comprising 
 two sets of medium through-flow channels through which two media can flow in counterflow in heat-exchanging contact with one another;    membranes separating said channels;    heat-conducting fins arranged on both sides of each membrane, which fins have a main plane extending in the respective flow directions of said media and a contact surface lying in the main plane of the membrane in question and connected thereto, wherein the contact surface of a fin on the one side of the membrane is aligned and in thermal contact with a similar contact surface of a fin on the other side of the membrane and wherein the contact surfaces are adhered to the membrane or to one another by means of an adhesive layer, the fins extending between two adjacent membranes such that, in addition to a thermal function, the fins also have a structural function; and    a housing in which the membranes with the fins are accommodated.    
     
     
         2 . Heat exchanger as claimed in  claim 1 , characterized in that corresponding contact surfaces are in thermal contact via the membrane.  
     
     
         3 . Heat exchanger as claimed in  claim 2 , characterized in that the contact surfaces are adhered to the membrane by means of an adhesive layer applied to at least one contact surface.  
     
     
         4 . Heat exchanger as claimed in  claim 2 , characterized in that corresponding contact surfaces are directly connected to each other via a perforation in the membrane by means of an adhesive layer applied to at least one contact surface.  
     
     
         5 . Heat exchanger as claimed in  claim 1 , characterized in that the housing is form-retaining and the membranes are connected to the housing in manner resistant to tensile stress, such that the tensile stresses occurring in the membranes as a result of a pressure difference between the two sets of channels can be absorbed by the housing.  
     
     
         6 . Heat exchanger as claimed in  claim 1 , characterized in that the membranes are biased such that, at a preselected maximum permissible pressure difference between the two sets of medium through-flow channels, the bending of the membrane between the free space defined by the contact surfaces of the fins, i.e. the bending of the membrane occurring at the relevant pressure divided by the relevant mutual distance between the contact surfaces in question, amounts to a maximum of 2.5%.  
     
     
         7 . Heat exchanger as claimed in  claim 2 , characterized in that the thermal resistance of the membrane transversely of its main plane amounts to a maximum of 0.1 of the thermal resistance in the case of direct contact between contact surfaces directed toward each other, and is therefore negligible.  
     
     
         8 . Heat exchanger as claimed in  claim 1 , characterized in that the thermal resistance of the membrane in its main plane over the mutual distance between two fins adjoining in flow direction is at least 10 times greater than in the case of fins directly coupled to each other thermally.  
     
     
         9 . Heat exchanger as claimed in  claim 1 , characterized in that the membranes consist of PET, for instance reinforced PET, that has been treated with a corona discharge and then provided with a primer, followed by an adhesive layer for connection to the contact surfaces of the fins.  
     
     
         10 . Heat exchanger as claimed in  claim 1 , characterized in that the membranes consist of PVC and that the fins are connected to the membranes by an ultrasonic treatment or a thermal treatment, in combination with pressure.  
     
     
         11 . Heat exchanger as claimed in  claim 1 , characterized in that the membrane consists of a fibre-reinforced material, which fibres consist for instance of glass, boron, carbon.  
     
     
         12 . Heat exchanger as claimed in  claim 1 , characterized in that the membranes consist of a plastic in which aluminium powder is embedded.  
     
     
         13 . Heat exchanger as claimed in  claim 1 , characterized in that the membrane or the adhesive layer applied thereto is conditioned so as to obtain a property from the group to which belong: 
 antibacterial properties    anti-adhesion properties to repel fouling and other growth    antistatic properties    surface tension-changing, which conditioning can for instance be applied by immersion or spraying with a suitable agent.    
     
     
         14 . Heat exchanger as claimed in  claim 1 , characterized in that the membranes protrude outside the fins such that they can be connected to a frame, for instance in order to place them under bias, or such that the protruding membrane parts can be thermally formed into interlacing units and manifolds for respectively joining together and separating again the sets, of channels.  
     
     
         15 . Heat exchanger as claimed in  claim 1 , characterized in that the heat exchanger is given a modular structure with blocks which can be releasably coupled to each other.  
     
     
         16 . Heat exchanger as claimed in  claim 1 , characterized in that the channels form a primary circuit P and a secondary circuit S and the membranes are connected in layers ordered in the sequence P, S, P, S, P, S and so on.  
     
     
         17 . Heat exchanger as claimed in  claim 1 , characterized in that the channels form a primary circuit P and a secondary circuit S and the membranes are connected in layers ordered in the sequence P, P, S, S, P, P and so on.  
     
     
         18 . Heat exchanger as claimed in  claim 1 , characterized in that the contact surfaces of the fins have rounded peripheral edges.  
     
     
         19 . Heat exchanger as claimed in  claim 11 , characterized in that the fibres have an anisotropic heat conduction, such as carbon fibres, wherein the heat conduction is smaller in the main plane of the membrane than in transverse direction thereof.  
     
     
         20 . Heat exchanger as claimed in any preceding claim, characterized in that the adhesive layer comprises an anticorrosive coating applied to at least one of the two contact surfaces and for instance comprising a primer layer and/or an adhesive layer extending over the whole surface of the fins and optionally the membrane.  
     
     
         21 . Heat exchanger as claimed in any preceding claim, characterized in that the adhesive layer is of the type which can be thermally activated and that the fins are adhered to the relevant membrane and/or to fins located opposite thereto at the position of the contact surfaces by heating and pressure by means of a heated pressing punch.  
     
     
         22 . Heat exchanger as claimed in claims  20  and  21 , characterized in that the fins are provided on the side remote from said coating with a second coating which can withstand said heating and pressure.  
     
     
         23 . Method for manufacturing a heat exchanger as claimed in  claim 1 , comprising 
 (a) providing a number of metal strips with a general wave shape;    (b) providing a number of widths of membrane material; and    (c) feeding these strips and widths into a connecting device in register and in alternating relationship and mutually connecting thereof to form a package by means of this device.