Method and Device for Ascertaining Fouling in a Heat Exchanger

Abstract

Device and method for ascertaining fouling in a heat exchanger in which heat is transferred from a first medium to a second medium through a wall, wherein a function is used with at least one parameter that describes the dependence of a first variable, which is influenced by the fouling, on the flow and/or temperature of the first medium and/or the second medium, in particular the simultaneous influence of changes in the flow and temperature on the first variable, wherein a value for the at least one parameter is ascertained using measurement values of the first and/or the second medium such that the precision when ascertaining fouling in a heat exchanger, in which heat is transferred from a first medium to a second medium, is increased.

1 - 17 . (canceled) 
     
     
         18 . A method for ascertaining fouling in a heat exchanger in which heat is transferred from a first medium to a second medium through a wall, the method comprising:
 utilizing a function with at least one parameter, said function describing a dependence of a first variable influenced by the fouling on at least one of a flow rate and a temperature of at least one of the first medium and the second medium comprising a simultaneous influence of changes in flow rate and temperature on the first variable; and   ascertaining a value for the at least one parameter aided by measured values of at least one of the first mediums and the second medium.   
     
     
         19 . The method as claimed in  claim 18 , wherein the first variable is ascertained from a heat balance of the heat exchanger. 
     
     
         20 . The method as claimed in  claim 18 , wherein a value for a variable characterizing the fouling is ascertained from a value for the first variable influenced by the fouling and a value of a second variable which compensates an influence of a dependence of the first variable on at least one of a flow rate and a temperature of at least one of the first medium and the second medium comprising a simultaneous influence of changes in flow rate and temperature on the first variable and wherein the value of the second variable is ascertained aided by the function with the at least one parameter. 
     
     
         21 . The method as claimed in  claim 18 , wherein said ascertaining the at least one parameter is based on measured values of temperatures of (i) at least one of the first medium and the second medium and (ii) at least one of flow rates of the at last one of the first medium and the second medium. 
     
     
         22 . The method as claimed in  claim 18 , wherein the function with the at least one parameter for at least one side of a wall, preferably for both sides of the wall, takes into account dependence of a heat transfer coefficient of a respective side on at least one of the flow rate and the temperature of the first or second medium which are each conducted past the side of the wall. 
     
     
         23 . The method as claimed in  claim 22 , wherein the dependence of the heat transfer coefficient on the flow rate of the medium which is conducted past the respective wall is in accordance with the relationship:
   α( F )= a·F ( t ) b ;
   wherein F is the flow rate of the medium at the respective side of the wall, t is time and a, b are parameters.   
     
     
         24 . The method as claimed in  claim 22 , wherein the dependence of the heat transfer coefficient on the temperature of the medium conducted past the respective wall in accordance with the relationship:
   α( T )= a ·( T ( t )+ b ) c ;
   wherein T is a mean temperature of the medium at the respective side of the wall, t is time and a, b, c are parameters.   
     
     
         25 . The method as claimed in  claim 22 , wherein the dependence of the heat transfer coefficient on at least one of the flow rate and the temperature of the medium conducted past the respective wall is in accordance with the relationship:
   α( F, T )= a·F   b ·( T+c ) d ;
   wherein F is a time-dependent flow rate and T is a time-dependent mean temperature of the medium at the respective side of the wall and a, b, c, d are parameters.   
     
     
         26 . The method as claimed in  claim 18 , wherein said ascertaining the at least one parameter comprises:
 providing a target function based on the function with the at least one parameter,   ascertaining the value of the at least one parameter by optimizing the target function based on measured values of at least one of flow rates and temperatures of at least one of the first and seconds medium aided by a parameter optimization algorithm.   
     
     
         27 . The method as claimed in  claim 26 , wherein the target function is based on an at least first-order time derivative of the function with the at least one parameter. 
     
     
         28 . The method as claimed in  claim 26 , wherein particle swarm optimization or an evolution strategy algorithm is utilized the parameter optimization algorithm. 
     
     
         29 . The method as claimed in  claim 27 , wherein particle swarm optimization or an evolution strategy algorithm is utilized the parameter optimization algorithm. 
     
     
         30 . The method as claimed in  claim 18 , wherein a value of a variable characterizing the fouling is ascertained without using material data for the first and second medium or without using geometry data for the heat exchanger. 
     
     
         31 . The method as claimed in  claim 18 , wherein a value of a variable characterizing the fouling is ascertained without using the material data or the geometry data. 
     
     
         32 . The method as claimed in  claim 18 , wherein a value of a variable characterizing the fouling is ascertained, preferably exclusively, from measured values of several of the following measured variables:
 (i) temperatures of the first medium and the second medium at an inlet and outlet of the heat exchanger, and   (ii) flow rates of the first medium and the second medium through the heat exchanger.   
     
     
         33 . The method as claimed in  claim 18 , wherein only relative values for a variable characterizing the fouling are ascertained. 
     
     
         34 . The method as claimed in  claim 18 , wherein heat transfer resistance or heat-transfer conductivity is utilized as a variable characterizing the fouling. 
     
     
         35 . A device for ascertaining fouling in a heat exchanger in which heat is transferred from a first medium to a second medium through a wall, said device comprising:
 a facility for receiving measured values or variables of the heat exchanger derived therefrom; and   an evaluating facility in which a function with at least one parameter describing a dependence of a first variable influenced by the fouling on at least one of a flow rate and a temperature of at least one of the first medium and the second medium comprising a simultaneous influence of changes in the flow rate and temperature on the first variable, is stored;   wherein the evaluating facility is configured to ascertain a value for the at least one parameter aided by the measured values or the variables derived therefrom of at least one of the first medium and the second medium.   
     
     
         36 . A computer program comprising instructions which, when executed on a computer, cause the computer to execute the method as claimed in  claim 18 .