Filter replacement lifetime prediction

Abstract

Methods for controlling air filtration in an enclosure include measuring contaminants in an internal and an external environment using respective internal and external contaminant sensors. An increase in a corrosion rate is determined for objects in the enclosure if unfiltered external air intake is increased for cooling based on the measured contaminants in the internal and external environments. An air pressure needed to filter external air using a filter in the filtered air intake is determined. An intake of unfiltered external air is controlled by bypassing the filter in the filtered air intake, based on the corrosion rate increase and the determined air pressure. A predicted filter lifetime is updated based on the intake of unfiltered external air. A warning is provided if the contaminant sensor information associated with the filter exceeds an instantaneous failure threshold or if the determined remaining filter lifetime falls below a filter lifetime threshold.

What is claimed is: 
     
         1 . A method for controlling air filtration in an enclosure having a filtered air intake and an unfiltered air intake, comprising:
 measuring contaminants in an internal and an external environment using respective internal and external contaminant sensors;   determining an increase in a corrosion rate for one or more objects in the enclosure if unfiltered external air intake is increased for cooling based on the measured contaminants in the internal and external environments;   determining an air pressure needed to filter external air using a filter in the filtered air intake;   controlling an intake of unfiltered external air by bypassing the filter in the filtered air intake, based on the corrosion rate increase and the air pressure needed to filter external air;   updating a predicted filter lifetime based on the intake of unfiltered external air, comprising:
 building a filter effectiveness history based on contaminant sensor information associated with a filter; 
 determining a rate of filter consumption with a processor based on the filter effectiveness history; and 
 determining a remaining filter lifetime based on the determined rate of filter consumption; and 
   providing a warning if the contaminant sensor information associated with the filter exceeds an instantaneous failure threshold or if the determined remaining filter lifetime falls below a filter lifetime threshold.   
     
     
         2 . The method of  claim 1 , wherein the rate of filter consumption characterizes a change over time in a degree of unfiltered contamination. 
     
     
         3 . The method of  claim 1 , wherein the remaining filter lifetime is a time remaining until the degree of unfiltered contamination is predicted to exceed a threshold. 
     
     
         4 . The method of  claim 1 , wherein the instantaneous failure threshold represents a physical failure of the filter. 
     
     
         5 . The method of  claim 1 , wherein the contaminant sensor information includes sensor information for gaseous and particulate contaminants. 
     
     
         6 . The method of  claim 5 , further comprising determining whether external conditions are within guideline levels for temperature, relative humidity, and corrosion rate. 
     
     
         7 . The method of  claim 1 , further comprising decreasing the intake of unfiltered external air if external conditions fall outside of guideline levels. 
     
     
         8 . A computer readable storage medium comprising a computer readable program, wherein the computer readable program when executed on a computer causes the computer to perform the steps of  claim 1 . 
     
     
         9 . The method of  claim 1 , wherein determining the rate of filter consumption comprises performing a time series analysis on the filter effectiveness history. 
     
     
         10 . The method of  claim 12 , wherein performing a time series analysis comprises applying a Kalman filter model to predict future filter consumption values. 
     
     
         11 . The method of  claim 1 , wherein determining the increase in the corrosion rate comprises calculating a corrosion rate of the external environment based on a concentration of gaseous contaminants, the relative humidity, the activation energy for a given metal, and the temperature. 
     
     
         12 . The method of  claim 1 , wherein measuring contaminants comprises measuring a contaminant concentration. 
     
     
         13 . A method for controlling air filtration in an enclosure having a filtered air intake and an unfiltered air intake, comprising:
 determining an increase in a corrosion rate for one or more objects in the enclosure if unfiltered external air intake is increased for cooling based on measured contaminants in the internal and external environments, comprising calculating a corrosion rate of the external environment as:   
       
         
           
             
               
                 CR 
                 out 
               
               ≈ 
               
                 
                   
                     ( 
                     
                       
                         H 
                         2 
                       
                        
                       S 
                     
                     ) 
                   
                   a 
                 
                  
                 
                   
                     ( 
                     
                       SO 
                       2 
                     
                     ) 
                   
                   b 
                 
                  
                 
                   
                     ( 
                     
                       NO 
                       2 
                     
                     ) 
                   
                   c 
                 
                  
                 
                   e 
                   
                     d 
                     · 
                     RH 
                   
                 
                  
                 
                   e 
                   
                     
                       E 
                       a 
                     
                      
                     
                       / 
                     
                      
                     
                       k 
                       B 
                     
                      
                     T 
                   
                 
               
             
           
         
       
       where H 2 S, SO 2 , and NO 2  are the gaseous contaminants hydrogen sulfide, sulfur dioxide, and nitrous oxide in parts per billion, RH is the relative humidity, E a  is the activation energy for a given metal, k B  is the Boltzmann constant, T is temperature, and the scaling variables a, b, c, and d are determined by fitting historical corrosion data versus variation of the gaseous pollutant concentration in a controlled or normal environment;
 determining an air pressure needed to filter external air using a filter in the filtered air intake; 
 controlling an intake of unfiltered external air by bypassing the filter in the filtered air intake, based on the corrosion rate increase and the air pressure needed to filter external air; 
 updating a predicted filter lifetime based on the intake of unfiltered external air; and 
 providing a warning if the contaminant sensor information associated with the filter exceeds an instantaneous failure threshold or if the determined remaining filter lifetime falls below a filter lifetime threshold.