Mixing device and method for controlling the temperature of a fluid flow

Abstract

A mixing device includes a first inlet (84) and a second inlet (86) inlet and an outlet (80). The first inlet (84) is connected to the outlet (80) via a first flow connection and the second inlet (86) is connected to the outlet (80) via a second flow connection. A circulation pump assembly (24; 46) includes an electric drive motor (30), a control device (34), for controlling the speed of the drive motor (30), and at least one impeller (68; 100) driven by the drive motor. The at least one impeller (68; 100) is positioned in the first flow connection. The flow connections are configured such that at least one hydraulic pressure generated by the impeller (68; 100) in the first flow connection acts as hydraulic resistance in the second flow connection.

1 . A mixing device comprising:
 a first inlet;   a second inlet;   an outlet;   a first flow connection;   a second flow connection, wherein the first inlet is connected to the outlet via the first flow connection and the second inlet is connected to the outlet via the second flow connection;   a circulation pump assembly comprising an electrical drive motor, a control device configured to control a speed the drive motor and impeller arrangement which is driven by the drive motor and is situated in the first flow connection, wherein the flow connections are configured such that at least one hydraulic pressure, which is produced in the first flow connection by the impeller, acts as a hydraulic resistance in the second flow connection.   
     
     
         2 . A mixing device according to  claim 1 , wherein the first flow connection and the second flow connection unify at a run-out point and the first flow connection and the second flow connection are configured such that the hydraulic resistance acts at the run-out point in the form of a counter-pressure. 
     
     
         3 . A mixing device according to  claim 1 , wherein the impeller arrangement comprises a first flow path which is part of the first flow connection, and a second flow path which is part of the second flow connection, wherein the flow paths are configured such that a hydraulic pressure which is produced in the first flow path acts as the hydraulic resistance in the second flow path and/or that a hydraulic pressure which is produced in the second flow path ( 28 :  50 ) acts as the hydraulic resistance in the first flow path. 
     
     
         4 . A mixing device according to  claim 1 , wherein:
 the impeller arrangement comprises two impellers which are arranged rotationally fixed to one another and which are commonly driven by the drive motor; and   a first flow path which is part of the first flow connection is formed in a first impeller of said two impellers and a second flow path which is part of the second flow connection is formed in a second impeller of said two impellers.   
     
     
         5 . A mixing device according to  claim 3 , wherein the first flow path and the second flow path are configured to effect pressure developments which are different from one another. 
     
     
         6 . A mixing device according to  claim 3 , wherein outlet sides of the first and second flow path are spaced different distances from a rotation axis (x) of the impeller arrangement in a radial direction thereof. 
     
     
         7 . A mixing device according to  claim 3 , wherein:
 the first flow path in the impeller arrangement runs from a first suction port to an outer periphery of the impeller arrangement; and   the second flow path extends from an inlet opening of the impeller to the outer periphery of the impeller arrangement; and   the inlet opening is situated radially between the first suction port and the outer periphery of the impeller.   
     
     
         8 . A mixing device according to  claim 7 , wherein the inlet opening runs out into a flow channel which runs between the first suction port and the outer periphery and which forms at least one section of the first flow path. 
     
     
         9 . A mixing device according to  claim 3 , wherein:
 the impeller arrangement comprises a first arrangement of impeller blades, between which first flow channels forming at least a part of the first flow path are situated, and a second arrangement of impeller blades, between which second flow channels forming at least a part of the second flow path are situated; and   the first arrangement of impeller blades and the second arrangement of impeller blades are situated in two planes which are offset in the direction of the rotation axis of the impeller.   
     
     
         10 . A mixing device according to  claim 9 , wherein the first arrangement of impeller blades has a different outer diameter than the second arrangement of impeller blades. 
     
     
         11 . A mixing device according to  claim 9 , wherein the first arrangement of impeller blades is connected to the first suction port of the impeller arrangement and the second arrangement of impeller blades is connected to a second suction port which annularly surrounds the first suction port or is arranged away from the first suction port. 
     
     
         12 . A mixing device according to  claim 1 , wherein the control device is configured to vary a speed of the drive motor for regulating a mixing ratio between a fluid flow through the first inlet and a fluid flow through the second inlet by way of changing the hydraulic resistance in at least the second flow connection. 
     
     
         13 . A mixing device according to  claim 1 , wherein the control device is connected to at least one temperature sensor ( 36 ) in the outlet and/or is configured for receiving a signal from at least one external temperature sensor and is configured to vary the speed of the drive motor in dependence on at least one received temperature signal. 
     
     
         14 . A heating system with a mixing device according to  claim 1 , wherein the first inlet of the mixing device is connected to a return of at least one heating circuit and the second inlet of the mixing device is connected to a feed which comes from a heat source ( 4 ). 
     
     
         15 . A heating system according to  claim 14 , further comprising a second circulation pump assembly arranged in the feed such that the second circulation pump assembly provides a fluid at a preliminary pressure at the second inlet of the mixing device. 
     
     
         16 . A method for temperature-adjustment of a fluid flow of a heating facility, the method comprising the steps of:
 mixing two differently temperature-adjusted fluid flows in a changeable mixing ratio, wherein the mixing comprises:   feeding the two differently temperature-adjusted fluid flows to a common mixing point, at which a hydraulic resistance acts upon at least one of the two fluid flows; and   changing the hydraulic resistance by way of a hydraulic means which acts upon at least one of the two fluid flows, for changing the mixing ratio.   
     
     
         17 . A method according to  claim 16 , wherein the hydraulic resistance is formed by fluid pressure at the mixing point. 
     
     
         18 . A method according to  claim 16 , wherein the hydraulic resistance is varied by changing fluid pressure of the first and/or the second fluid flow. 
     
     
         19 . A method according to  claim 16 , wherein a changeable pressure increase is effected in at least one of the two fluid flows by way of a pressure boosting means, wherein the pressure increase is effected by an impeller of a centrifugal pump assembly. 
     
     
         20 . A method according to  claim 19 , wherein one of the two fluid flows already has a higher preliminary pressure than the other fluid flow before the action of the pressure boosting means.