Surface with reduced particle deposition and reduced ice formation

Abstract

The invention relates in general to surfaces along which media, such as gases, liquids or multi-phase mixtures are flowing, especially to a device for transportation of a flowing medium and/or for heat exchange between a flowing medium and the device, and methods of producing and using such devices. Disclosed is a surface or layer having dimples, the edges of which are rounded, thereby forming a central dimple area and at least one curvature area for each dimple which continuously connects the dimple to the surrounding surface for reducing particle deposition and ice formation on a surface along which a medium flows.

1 . A device for transportation of a flowing medium and/or for heat exchange between the flowing medium and the device, comprising at least one surface having a plurality of dimples.  
   
   
       2 . The device according to  claim 1 , wherein the plurality of dimples are arranged periodically.  
   
   
       3 . The device according to  claim 1 , wherein the plurality of dimples comprises three adjoining dimples each having a center, the centers of three adjoining dimples forming an equilateral triangle, the distance between the centers of two adjoining dimples of the equilateral triangle having a first constant value and the distance between two consecutive rows of the plurality of dimples having a second constant value.  
   
   
       4 . The device according to  claim 1 , wherein the plurality of dimples have a two-dimensional edge.  
   
   
       5 . The device according to  claim 1 , wherein the plurality of dimples are rounded at an edge towards a remaining surface.  
   
   
       6 . The device according to  claim 1 , wherein the plurality of dimples each comprise a section of a sphere or an ellipsoid.  
   
   
       7 . The device according to  claim 1 , further comprising a transport channel, wherein the at least one surface is provided as an inner surface of the transport channel.  
   
   
       8 . The device according to  claim 7 , wherein the transport channel comprises a pipe.  
   
   
       9 . The device according  claim 1 , wherein the at least one surface is provided such that, in the proximity to the at least one surface, vortices are formed in the flowing medium when the flowing medium flows along the at least one surface.  
   
   
       10 . The device according to  claim 2 , wherein the deposition of particles on the at least one surface having a periodic dimple structure is reduced in comparison to a flat surface when the flowing medium flows along the at least one surface.  
   
   
       11 . The device according to  claim 2 , wherein the formation of ice on the at least one surface having a periodic dimple structure is reduced in comparison to a flat surface when the flowing medium flows along the at least one surface, and the at least one surface has a lower temperature than the flowing medium.  
   
   
       12 . A surface along which a medium flows, the medium consisting of a gas, a liquid, a two-phase mixture, or a mixture of multiple phases, the surface comprising dimples, wherein the edges of the dimples are rounded, thereby forming a central dimple area and at least one curvature area for each dimple which continuously connects each dimple to the surrounding surface.  
   
   
       13 . The surface according to  claim 12 , wherein the central dimple area has the form of a section of a sphere or an ellipsoid.  
   
   
       14 . The surface according to  claim 13 , wherein the curvature area comprises at least a first curvature area and a second curvature area, the first curvature area having a different curvature than the second curvature area.  
   
   
       15 . The surface according to  claim 14 , wherein the first curvature area is rounded with a first rounding radius and the second curvature area is rounded with a second rounding radius.  
   
   
       16 . The surface according to  claim 15 , wherein the central dimple area has the form of a section of a sphere, and the forms of the central dimple area of the first curvature area and of the second curvature area in a cross section perpendicular to the surface and through a center of the dimple, are defined by the following parameters: 
 d 1 : diameter of the central dimple area;    d 2 : outer diameter of the first curvature area;    t 1 : outer diameter of the second curvature area;    R 1 , C 1 : radius and center point of the sphere, the section of which forms the surface of the central dimple area;    R 2 , C 2 : radius and center point of the rounding radius of the first curvature area;    R 3 , C 3 : radius and center point of the rounding radius of the second curvature area;    P 1 : transition point from the central dimple area to the first curvature area;    P 2 : transition point from the first curvature area to the second curvature area;    P 3 : transition point from the second curvature area to the surrounding surface;    h 1 : difference in height between the lowest point of the central dimple area and the outer rim of the central dimple area;    h 2 : difference in height between the inner rim of the first curvature area and the outer rim of the first curvature area;    h 3 : difference in height between the inner rim of the second curvature area and the outer rim of the second curvature area;    α 1 : angle between the y-axis and a line connecting C 2  and C 3 ;    α 2 : angle between the x-axis and a line connecting C 1  and C 2 ;    f: parameter related to the portion of the surface covered by the central dimple area in relation to the combined area of central dimple area and curvature areas; 
 a set of parameters, comprising d 1 , α 1 , α 2 , R 2 /R 1  and f, are chosen and a remaining set of parameters are calculated by the following equations with a tolerance of ±10% for each parameter:  
                   R   1     =       d   1         2   ·   sin     ⁢           ⁢     α   1           ,                   R   2     =         R   2       R   1       ·       d   1         2   ·   sin     ⁢           ⁢     α   1             ,                   R   3     =         t   1     -         d   1     2     ·       R   2       R   1       ·       (     1   -     sin   ⁢           ⁢     α   1         )       sin   ⁢           ⁢     α   2               sin   ⁢           ⁢     α   2           ,                   h   1     =         d   1     2     ·       (     1   -     cos   ⁢           ⁢     α   1         )       sin   ⁢           ⁢     α   1             ,                   h   2     =       R   2     ·     (       cos   ⁢           ⁢     α   2       -     cos   ⁢           ⁢     α   1         )         ,                   h   3     =       R   3     ·     (     1   -     cos   ⁢           ⁢     α   2         )         ,                 H   =       h   1     +     h   2     +     h   3         ,                   t   1     =         π     6   ·   f         ·     d   1         ,                       C   1     =     (       X     C   ⁢           ⁢   1       ,     Y     C   ⁢           ⁢   1         )           with             X     C   ⁢           ⁢   1       =   0     ,               Y     C   ⁢           ⁢   1       =       R   1     -   H       ,                             C   2     =     (       X     C   ⁢           ⁢   2       ,     Y     C   ⁢           ⁢   2         )           with             X     C   ⁢           ⁢   2       =         d   1     2     ·     (     1   +       R   2       R   1         )         ,               Y     C   ⁢           ⁢   2       =       R   3     +         X     C   ⁢           ⁢   3       -     X     C   ⁢           ⁢   2           tg   ⁢           ⁢     α   2             ,                             C   3     =     (       X     C   ⁢           ⁢   3       ,     Y     C   ⁢           ⁢   3         )           with             X     C   ⁢           ⁢   3       =       t   1     2       ,               Y     C   ⁢           ⁢   3       =     -     R   3         ,                             P   1     =     (       X     P   ⁢           ⁢   1       ,     Y     P   ⁢           ⁢   1         )           with             X     P   ⁢           ⁢   1       =       d   1     2       ,               Y     P   ⁢           ⁢   1       =     H   -     h   1         ,                             P   2     =     (       X     P   ⁢           ⁢   2       ,     Y     P   ⁢           ⁢   2         )           with             X     P   ⁢           ⁢   2       =         t   1     2     -         R   3     ·   sin     ⁢           ⁢     α   2           ,               Y     P   ⁢           ⁢   2       =       R   3     ·     (       cos   ⁢           ⁢     α   2       -   1     )         ,                             P   3     =     (       X     P   ⁢           ⁢   3       ,     Y     P   ⁢           ⁢   3         )           with             X     P   ⁢           ⁢   3       =       t   1     2       ,               Y     P   ⁢           ⁢   3       =   0     ,                     
 the equations being defined in a two-dimensional coordinate-system with an x-axis in the plane of the surface and with a y-axis through the center of the dimple and perpendicular to the surface.  
   
   
   
       17 . The surface according to  claim 12 , wherein the dimples are arranged periodically on the surface.  
   
   
       18 . The surface according to  claim 17 , wherein the dimples comprises three adjoining dimples each having a center, the centers of three adjoining dimples forming a triangle, the distance between two adjoining dimples of the triangle having a first constant value and the distance between two rows of the plurality of dimples having a second constant value.  
   
   
       19 . The surface according to  claim 18 , wherein the at least one curvature areas of the three adjoining dimples are in contact with each other.  
   
   
       20 . The surface according to  claim 18  further comprising additional dimples of a different size located in the center of the three adjoining dimples.  
   
   
       21 - 24 . (canceled)  
   
   
       25 . A device for transportation of a flowing medium, comprising at least one surface with dimples according to  claim 12 .  
   
   
       26 . The device according to  claim 25 , comprising a transport channel, wherein the at least one surface is provided as the inner surface of the transport channel.  
   
   
       27 . The device according to  claim 26 , wherein the transport channel is a pipe.  
   
   
       28 . The device according to  claim 25 , comprising at least one surface, wherein the deposition of particles on the at least one surface is reduced in comparison to an otherwise identical device with a flat surface.  
   
   
       29 . The device according to  claim 25  for heat exchange between the flowing medium and at least one surface, wherein the at least one surface is part of an air-conditioning system.  
   
   
       30 . The device according to  claim 29 , comprising at least one surface, wherein the formation of ice on the at least one surface is reduced in comparison to an otherwise identical device with a flat surface.  
   
   
       31 . A layer for applying on a surface, wherein the layer comprises a surface according to  claim 1 .  
   
   
       32 . The layer according to  claim 31 , further comprising a first side and a second side, wherein the first side comprises dimples and the second side is self-adhesive.  
   
   
       33 . A method for producing a surface having reduced particle deposition and/or reduced ice formation and/or reduced friction resistance and/or improved heat exchange with a surrounding medium, comprising the step of 
 applying the layer according to  claim 31  onto the surface.    
   
   
       34 . The method according to  claim 33 , for producing a surface having reduced particle deposition and/or reduced ice formation and/or reduced friction resistance and/or improved heat exchange with a surrounding medium, further comprising the steps of 
 providing a workpiece with at least one surface; and    imprinting into said the at least one surface a structure comprising dimples.    
   
   
       35 . The method for producing a surface according to  claim 34  having reduced particle deposition and/or reduced ice formation and/or reduced friction resistance and/or improved heat exchange with a surrounding medium, comprising the steps of 
 providing a casting mold with at least one structured surface; and    molding a workpiece with at least one surface comprising dimples, by casting mold.    
   
   
       36 . The method according to  claim 35 , further comprising the step of applying the at least one surface comprising dimples as the surface of: 
 a device for transportation of a medium or    a device for heat exchange.    
   
   
       37 . The method according to  claim 36 , further comprising the step of applying the device in an air-conditioning system.  
   
   
       38 . The method according to  claim 35 , further comprising the step of applying the at least one surface comprising dimples as a surface of a flow channel for reducing the deposition of particles and/or for reducing ice formation when a medium flows along the surface.  
   
   
       39 . (canceled)  
   
   
       40 . An air-conditioning system for cooling a heat exchange medium, comprising the at least one flow channel according to  claim 38  for the heat exchange medium, wherein the inner surface of the at least one flow channel is provided with a plurality of dimples.