Peclet Number

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

P├ęclet number, abbreviated as Pe, a dimensionless number, defined as a ratio of heat transport by convection to heat transport by conduction.

 

Peclet Number fromula

\(\large{ Pe =  \frac { v \; \rho \; C  \; l_c }{ k }      }\)   

Where:

 Units English Metric
\(\large{ Pe  }\) = Peclet number \(\large{dimensionless}\)
\(\large{ l_c }\) = characteristic length \(\large{ft}\) \(\large{m}\)
\(\large{ \rho  }\)  (Greek symbol rho) = density \(\large{\frac{lbm}{ft^3}}\) \(\large{\frac{kg}{m^3}}\)
\(\large{ Q_{cond}  }\) = heat transfer by conduction \(\large{\frac{Btu}{hr}}\) \(\large{W}\) 
\(\large{ Q_{conv}  }\) = heat transfer by convection \(\large{\frac{Btu}{hr}}\) \(\large{W}\) 
\(\large{ C }\) = heat capacity \(\large{\frac{Btu}{F}}\)  \(\large{\frac{kJ}{K}}\) 
\(\large{ k }\) = thermal conductivity \(\large{\frac{Btu-ft}{hr-ft^2-F}}\) \(\large{\frac{W}{m-K}}\)
\(\large{ v  }\) = velocity \(\large{\frac{ft}{sec}}\) \(\large{\frac{m}{s}}\)

Solve For:

\(\large{ l_c =  \frac { Pe \; k }{ v \; \rho \; C }   }\)   
\(\large{ \rho =  \frac { Pe \; k }{ v \; C \; l_c }   }\)  
\(\large{ C =  \frac { Pe \; k }{ v \; \rho \; l_c }   }\)  
\(\large{ k =  \frac { v \; \rho \; C \; l_c  }{ Pe }   }\)  
\(\large{ v =  \frac { Pe \; k }{ \rho \; C \; l_c }   }\)  

 

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Tags: Thermal Conductivity Equations Temperature Equations